path: root/doc/rfc/rfc7105.txt

Internet Engineering Task Force (IETF)                        M. Thomson
Request for Comments: 7105                                       Mozilla
Category: Standards Track                                J. Winterbottom
ISSN: 2070-1721                                             Unaffiliated
                                                            January 2014


          Using Device-Provided Location-Related Measurements
                  in Location Configuration Protocols

Abstract

   This document describes a protocol for a Device to provide location-
   related measurement data to a Location Information Server (LIS)
   within a request for location information.  Location-related
   measurement information provides observations concerning properties
   related to the position of a Device; this information could be data
   about network attachment or about the physical environment.  A LIS is
   able to use the location-related measurement data to improve the
   accuracy of the location estimate it provides to the Device.  A basic
   set of location-related measurements are defined, including common
   modes of network attachment as well as assisted Global Navigation
   Satellite System (GNSS) parameters.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7105.














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Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................4
   2. Conventions Used in This Document ...............................5
   3. Location-Related Measurements in LCPs ...........................6
   4. Location-Related Measurement Data Types .........................7
      4.1. Measurement Container ......................................7
           4.1.1. Time of Measurement .................................8
           4.1.2. Expiry Time on Location-Related Measurement Data ....8
      4.2. RMS Error and Number of Samples ............................9
           4.2.1. Time RMS Error ......................................9
      4.3. Measurement Request .......................................10
      4.4. Identifying Location Provenance ...........................11
   5. Location-Related Measurement Data Types ........................13
      5.1. LLDP Measurements .........................................13
      5.2. DHCP Relay Agent Information Measurements .................14
      5.3. 802.11 WLAN Measurements ..................................15
           5.3.1. WiFi Measurement Requests ..........................18
      5.4. Cellular Measurements .....................................18
           5.4.1. Cellular Measurement Requests ......................22
      5.5. GNSS Measurements .........................................22
           5.5.1. GNSS: System Type and Signal .......................23
           5.5.2. Time ...............................................24
           5.5.3. Per-Satellite Measurement Data .....................24
           5.5.4. GNSS Measurement Requests ..........................25
      5.6. DSL Measurements ..........................................25
           5.6.1. L2TP Measurements ..................................26
           5.6.2. RADIUS Measurements ................................26
           5.6.3. Ethernet VLAN Tag Measurements .....................27
           5.6.4. ATM Virtual Circuit Measurements ...................28






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   6. Privacy Considerations .........................................28
      6.1. Measurement Data Privacy Model ............................28
      6.2. LIS Privacy Requirements ..................................29
      6.3. Measurement Data and Location URIs ........................29
      6.4. Measurement Data Provided by a Third Party ................30
   7. Security Considerations ........................................30
      7.1. Threat Model ..............................................30
           7.1.1. Acquiring Location Information without
                  Authorization ......................................31
           7.1.2. Extracting Network Topology Data ...................32
           7.1.3. Exposing Network Topology Data .....................32
           7.1.4. Lying by Proxy .....................................33
           7.1.5. Measurement Replay .................................33
           7.1.6. Environment Spoofing ...............................34
      7.2. Mitigation ................................................35
           7.2.1. Measurement Validation .............................36
                  7.2.1.1. Effectiveness .............................36
                  7.2.1.2. Limitations (Unique Observer) .............37
           7.2.2. Location Validation ................................38
                  7.2.2.1. Effectiveness .............................38
                  7.2.2.2. Limitations ...............................39
           7.2.3. Supporting Observations ............................39
                  7.2.3.1. Effectiveness .............................40
                  7.2.3.2. Limitations ...............................40
           7.2.4. Attribution ........................................40
           7.2.5. Stateful Correlation of Location Requests ..........42
      7.3. An Unauthorized or Compromised LIS ........................42
   8. Measurement Schemas ............................................42
      8.1. Measurement Container Schema ..............................43
      8.2. Measurement Source Schema .................................45
      8.3. Base Types Schema .........................................46
      8.4. LLDP Measurement Schema ...................................49
      8.5. DHCP Measurement Schema ...................................50
      8.6. WiFi Measurement Schema ...................................51
      8.7. Cellular Measurement Schema ...............................55
      8.8. GNSS Measurement Schema ...................................57
      8.9. DSL Measurement Schema ....................................59
   9. IANA Considerations ............................................61
      9.1. IANA Registry for GNSS Types ..............................61
      9.2. URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:pidf:geopriv10:lmsrc ...............62
      9.3. URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:geopriv:lm .........................63
      9.4. URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:geopriv:lm:basetypes ...............63
      9.5. URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:geopriv:lm:lldp ....................64




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      9.6. URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:geopriv:lm:dhcp ....................65
      9.7. URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:geopriv:lm:wifi ....................65
      9.8. URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:geopriv:lm:cell ....................66
      9.9. URN Sub-Namespace Registration for
           urn:ietf:params:xml:ns:geopriv:lm:gnss ....................67
      9.10. URN Sub-Namespace Registration for
            urn:ietf:params:xml:ns:geopriv:lm:dsl ....................67
      9.11. XML Schema Registration for Measurement Source Schema ....68
      9.12. XML Schema Registration for Measurement Container
            Schema ...................................................68
      9.13. XML Schema Registration for Base Types Schema ............69
      9.14. XML Schema Registration for LLDP Schema ..................69
      9.15. XML Schema Registration for DHCP Schema ..................69
      9.16. XML Schema Registration for WiFi Schema ..................69
      9.17. XML Schema Registration for Cellular Schema ..............70
      9.18. XML Schema Registration for GNSS Schema ..................70
      9.19. XML Schema Registration for DSL Schema ...................70
   10. Acknowledgements ..............................................70
   11. References ....................................................71
      11.1. Normative References .....................................71
      11.2. Informative References ...................................73

1.  Introduction

   A Location Configuration Protocol (LCP) provides a means for a Device
   to request information about its physical location from an access
   network.  A Location Information Server (LIS) is the server that
   provides location information that is available due to the knowledge
   it has about the network and physical environment.

   As a part of the access network, the LIS is able to acquire
   measurement results related to Device location from network elements.
   The LIS also has access to information about the network topology
   that can be used to turn measurement data into location information.
   This information can be further enhanced with information acquired
   from the Device itself.

   A Device is able to make observations about its network attachment,
   or its physical environment.  The location-related measurement data
   might be unavailable to the LIS; alternatively, the LIS might be able
   to acquire the data, but at a higher cost in terms of time or some
   other metric.  Providing measurement data gives the LIS more options
   in determining location; this could in turn improve the quality of





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   the service provided by the LIS.  Improvements in accuracy are one
   potential gain, but improved response times and lower error rates are
   also possible.

   This document describes a means for a Device to report location-
   related measurement data to the LIS.  Examples based on the
   HTTP-Enabled Location Delivery (HELD) [RFC5985] location
   configuration protocol are provided.

2.  Conventions Used in This Document

   The terms "LIS" and "Device" are used in this document in a manner
   consistent with the usage in [RFC5985].

   This document also uses the following definitions:

   Location Measurement:  An observation about the physical properties
      of a particular Device's position in time and space.  The result
      of a location measurement -- "location-related measurement data",
      or simply "measurement data" given sufficient context -- can be
      used to determine the location of a Device.  Location-related
      measurement data does not directly identify a Device, though it
      could do so indirectly.  Measurement data can change with time if
      the location of the Device also changes.

      Location-related measurement data does not necessarily contain
      location information directly, but it can be used in combination
      with contextual knowledge and/or algorithms to derive location
      information.  Examples of location-related measurement data are
      radio signal strength or timing measurements, Ethernet switch
      identifiers, and port identifiers.

      Location-related measurement data can be considered sighting
      information, based on the definition in [RFC3693].

   Location Estimate:  An approximation of where the Device is located.
      Location estimates are derived from location measurements.
      Location estimates are subject to uncertainty, which arises from
      errors in measurement results.

   GNSS:  Global Navigation Satellite System.  A satellite-based system
      that provides positioning and time information -- for example, the
      US Global Positioning System (GPS) or the European Galileo system.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].




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3.  Location-Related Measurements in LCPs

   This document defines a standard container for the conveyance of
   location-related measurement parameters in location configuration
   protocols.  This is an XML container that identifies parameters by
   type and allows the Device to provide the results of any measurement
   it is able to perform.  A set of measurement schemas are also defined
   that can be carried in the generic container.

   A simple example of measurement data conveyance is illustrated by the
   example message in Figure 1.  This shows a HELD location request
   message with an Ethernet switch and port measurement taken using the
   Link-Layer Discovery Protocol (LLDP) [IEEE.8021AB].

     <locationRequest xmlns="urn:ietf:params:xml:ns:geopriv:held">
       <locationType exact="true">civic</locationType>
       <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
             time="2008-04-29T14:33:58">
         <lldp xmlns="urn:ietf:params:xml:ns:geopriv:lm:lldp">
           <chassis type="4">0a01003c</chassis>
           <port type="6">c2</port>
         </lldp>
       </measurements>
     </locationRequest>

           Figure 1: HELD Location Request with Measurement Data

   This LIS can ignore measurement data that it does not support or
   understand.  The measurements defined in this document follow this
   rule: extensions that could result in backward incompatibility MUST
   be added as new measurement definitions rather than extensions to
   existing types.

   Multiple sets of measurement data, either of the same type or from
   different sources, can be included in the "measurements" element.
   See Section 4.1.1 for details on repetition of this element.

   A LIS can choose to use or ignore location-related measurement data
   in determining location, as long as rules regarding use and retention
   (Section 6) are respected.  The "method" parameter in the Presence
   Information Data Format - Location Object (PIDF-LO) [RFC4119] SHOULD
   be adjusted to reflect the method used.  A correct "method" can
   assist location recipients in assessing the quality (both accuracy
   and integrity) of location information, though there could be reasons
   to withhold information about the source of data.






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   Measurement data is typically only used to serve the request in which
   it is included.  There may be exceptions, particularly with respect
   to location URIs.  Section 6 provides more information on usage
   rules.

   Location-related measurement data need not be provided exclusively by
   Devices.  A third-party location requester (for example, see
   [RFC6155]) can request location information using measurement data,
   if the requester is able to acquire measurement data and authorized
   to distribute it.  There are specific privacy considerations relating
   to the use of measurements by third parties, which are discussed in
   Section 6.4.

   Location-related measurement data and its use present a number of
   privacy and security challenges.  These are described in more detail
   in Sections 6 and 7.

4.  Location-Related Measurement Data Types

   A common container is defined for the expression of location
   measurement data, as well as a simple means of identifying specific
   types of measurement data for the purposes of requesting them.

   The following example shows a measurement container with measurement
   time and expiration time included.  A WiFi measurement is enclosed.

     <lm:measurements xmlns:lm="urn:ietf:params:xml:ns:geopriv:lm"
              time="2008-04-29T14:33:58"
              expires="2008-04-29T17:33:58">
       <wifi xmlns="urn:ietf:params:xml:ns:geopriv:lm:wifi">
         <ap serving="true">
           <bssid>00-12-F0-A0-80-EF</bssid>
           <ssid>wlan-home</ssid>
         </ap>
       </wifi>
     </lm:measurements>

                       Figure 2: Measurement Example

4.1.  Measurement Container

   The "measurements" element is used to encapsulate measurement data
   that is collected at a certain point in time.  It contains time-based
   attributes that are common to all forms of measurement data, and it
   permits the inclusion of arbitrary measurement data.  The elements
   that are included within the "measurements" element are generically
   referred to as "measurement elements".




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   This container can be added to a request for location information in
   any protocol capable of carrying XML, such as a HELD location request
   [RFC5985].

4.1.1.  Time of Measurement

   The "time" attribute records the time that the measurement or
   observation was made.  This time can be different from the time that
   the measurement information was reported.  Time information can be
   used to populate a timestamp on the location result or to determine
   if the measurement information is used.

   The "time" attribute SHOULD be provided whenever possible.  This
   allows a LIS to avoid selecting an arbitrary timestamp.  Exceptions
   to this, where omitting time might make sense, include relatively
   static types of measurement (for instance, the DSL measurements in
   Section 5.6) or for legacy Devices that don't record time information
   (such as the Home Location Register/Home Subscriber Server for
   cellular).

   The "time" attribute is attached to the root "measurement" element.
   Multiple measurements can often be given the same timestamp, even
   when the measurements were not actually taken at the same time
   (consider a set of measurements taken sequentially, where the
   difference in time between observations is not significant).
   Measurements cannot be grouped if they have different types or if
   there is a need for independent time values on each measurement.  In
   these instances, multiple measurement sets are necessary.

4.1.2.  Expiry Time on Location-Related Measurement Data

   A Device is able to indicate an expiry time in the location
   measurement using the "expires" attribute.  Nominally, this attribute
   indicates how long information is expected to be valid, but it can
   also indicate a time limit on the retention and use of the
   measurement data.  A Device can use this attribute to request that
   the LIS not retain measurement data beyond the indicated time.

      Note: Movement of the Device might result in the measurement data
      being invalidated before the expiry time.

   A Device is advised to set the "expires" attribute to the earlier of
   the time that measurements are likely to be unusable and the time
   that it desires to have measurements discarded by the LIS.  A Device
   that does not desire measurement data to be retained can omit the
   "expires" attribute.  Section 6 describes more specific rules
   regarding measurement data retention.




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4.2.  RMS Error and Number of Samples

   Often a measurement is taken more than once.  Reporting the average
   of a number of measurement results mitigates the effects of random
   errors that occur in the measurement process.

   Reporting each measurement individually can be the most effective
   method of reporting multiple measurements.  This is achieved by
   providing multiple measurement elements for different times.

   The alternative is to aggregate multiple measurements and report a
   mean value across the set of measurements.  Additional information
   about the distribution of the results can be useful in determining
   location uncertainty.

   Two attributes are provided for use on some measurement values:

   rmsError:  The root-mean-squared (RMS) error of the set of
      measurement values used in calculating the result.  RMS error is
      expressed in the same units as the measurement, unless otherwise
      stated.  If an accurate value for the RMS error is not known, this
      value can be used to indicate an upper bound or estimate for the
      RMS error.

   samples:  The number of samples that were taken in determining the
      measurement value.  If omitted, this value can be assumed to be
      large enough that the RMS error is an indication of the standard
      deviation of the sample set.

   For some measurement techniques, measurement error is largely
   dependent on the measurement technique employed.  In these cases,
   measurement error is largely a product of the measurement technique
   and not the specific circumstances, so the RMS error does not need to
   be actively measured.  A fixed value MAY be provided for the RMS
   error where appropriate.

   The "rmsError" and "samples" elements are added as attributes of
   specific measurement data types.

4.2.1.  Time RMS Error

   Measurement of time can be significant in certain circumstances.  The
   GNSS measurements included in this document are one such case where a
   small error in time can result in a large error in location.  Factors
   such as clock drift and errors in time synchronization can result in
   small, but significant, time errors.  Including an indication of the
   quality of time measurements can be helpful.




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   A "timeError" attribute MAY be added to the "measurement" element to
   indicate the RMS error in time.  "timeError" indicates an upper bound
   on the time RMS error in seconds.

   The "timeError" attribute does not apply where multiple samples of a
   measurement are taken over time.  If multiple samples are taken, each
   SHOULD be included in a different "measurement" element.

4.3.  Measurement Request

   A measurement request is used by a protocol peer to describe a set of
   measurement data that it desires.  A "measurementRequest" element is
   defined that can be included in a protocol exchange.

   For instance, a LIS can use a measurement request in HELD responses.
   If the LIS is unable to provide location information, but it believes
   that a particular measurement type would enable it to provide a
   location, it can include a measurement request in an error response.

   The "measurement" element of the measurement request identifies the
   type of measurement that is requested.  The "type" attribute of this
   element indicates the type of measurement, as identified by an XML
   qualified name.  A "samples" attribute MAY be used to indicate how
   many samples of the identified measurement are requested.

   The "measurement" element can be repeated to request multiple (or
   alternative) measurement types.

   Additional XML content might be defined for a particular measurement
   type that is used to further refine a request.  These elements either
   constrain what is requested or specify non-mandatory components of
   the measurement data that are needed.  These are defined along with
   the specific measurement type.

   In the HELD protocol, the inclusion of a measurement request in an
   error response with a code of "locationUnknown" indicates that
   providing measurements would increase the likelihood of a subsequent
   request being successful.













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   The following example shows a HELD error response that indicates that
   WiFi measurement data would be useful if a later request were made.
   Additional elements indicate that received signal strength for an
   802.11n access point is requested.

     <error xmlns="urn:ietf:params:xml:ns:geopriv:held"
        code="locationUnknown">
       <message xml:lang="en">Insufficient measurement data</message>
       <measurementRequest
       xmlns="urn:ietf:params:xml:ns:geopriv:lm"
       xmlns:wifi="urn:ietf:params:xml:ns:geopriv:lm:wifi">
         <measurement type="wifi:wifi">
           <wifi:type>n</wifi:type>
           <wifi:parameter context="ap">wifi:rcpi</wifi:parameter>
         </measurement>
       </measurementRequest>
     </error>

             Figure 3: HELD Error Requesting Measurement Data

   A measurement request that is included in other HELD messages has
   undefined semantics and can be safely ignored.  Other specifications
   might define semantics for measurement requests under other
   conditions.

4.4.  Identifying Location Provenance

   An extension is made to the PIDF-LO [RFC4119] that allows a location
   recipient to identify the source (or sources) of location information
   and the measurement data that was used to determine that location
   information.

   The "source" element is added to the "geopriv" element of the
   PIDF-LO.  This element does not identify specific entities.  Instead,
   it identifies the type of measurement source.

   The following values are defined for the "source" element:

   lis:  Location information is based on measurement data that the LIS
      or sources that it trusts have acquired.  This label MAY be used
      if measurement data provided by the Device has been completely
      validated by the LIS.

   device:  A LIS MUST include this value if the location information is
      based (in whole or in part) on measurement data provided by the
      Device and if the measurement data isn't completely validated.





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   other:  Location information is based on measurement data that a
      third party has provided.  This might be an authorized third party
      that uses identity parameters [RFC6155] or any other entity.  The
      LIS MUST include this, unless the third party is trusted by the
      LIS to provide measurement data.

   No assertion is made about the veracity of the measurement data from
   sources other than the LIS.  A combination of tags MAY be included to
   indicate that measurement data from multiple types of sources was
   used.

   For example, the first tuple of the following PIDF-LO indicates that
   measurement data from a LIS and a Device was combined to produce the
   result; the second tuple was produced by the LIS alone.

     <presence xmlns="urn:ietf:params:xml:ns:pidf"
           xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10"
           xmlns:gml="http://www.opengis.net/gml"
           xmlns:gs="http://www.opengis.net/pidflo/1.0"
           xmlns:lmsrc="urn:ietf:params:xml:ns:pidf:geopriv10:lmsrc"
           entity="pres:lm@example.com">
       <tuple id="deviceLoc">
         <status>
           <gp:geopriv>
             <gp:location-info>
               <gs:Circle srsName="urn:ogc:def:crs:EPSG::4326">
                 <gml:pos>7.34324 134.47162</gml:pos>
                 <gs:radius uom="urn:ogc:def:uom:EPSG::9001">
                   850.24
                 </gs:radius>
               </gs:Circle>
             </gp:location-info>
             <gp:usage-rules/>
             <gp:method>OTDOA</gp:method>
             <lmsrc:source>lis device</lmsrc:source>
           </gp:geopriv>
         </status>
       </tuple>
       <tuple id="lisLoc">
         <status>
           <gp:geopriv>
             <gp:location-info>
               <gs:Circle srsName="urn:ogc:def:crs:EPSG::4326">
                 <gml:pos>7.34379 134.46484</gml:pos>
                 <gs:radius uom="urn:ogc:def:uom:EPSG::9001">
                   9000
                 </gs:radius>
               </gs:Circle>



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             </gp:location-info>
             <gp:usage-rules/>
             <gp:method>Cell</gp:method>
             <lmsrc:source>lis</lmsrc:source>
           </gp:geopriv>
         </status>
       </tuple>
     </presence>

                    PIDF-LO Document with Source Labels

5.  Location-Related Measurement Data Types

   This document defines location-related measurement data types for a
   range of common network types.

   All included measurement data definitions allow for arbitrary
   extension in the corresponding schema.  New parameters that are
   applicable to location determination are added as new XML elements in
   a unique namespace, not by adding elements to an existing namespace.

5.1.  LLDP Measurements

   Link-Layer Discovery Protocol (LLDP) [IEEE.8021AB] messages are sent
   between adjacent nodes in an IEEE 802 network (e.g., wired Ethernet,
   WiFi, 802.16).  These messages all contain identification information
   for the sending node; the identification information can be used to
   determine location information.  A Device that receives LLDP messages
   can report this information as a location-related measurement to the
   LIS, which is then able to use the measurement data in determining
   the location of the Device.

      Note: The LLDP extensions defined in LLDP Media Endpoint Discovery
      (LLDP-MED) [ANSI-TIA-1057] provide the ability to acquire location
      information directly from an LLDP endpoint.  Where this
      information is available, it might be unnecessary to use any other
      form of location configuration.

   Values are provided as hexadecimal sequences.  The Device MUST report
   the values directly as they were provided by the adjacent node.
   Attempting to adjust or translate the type of identifier is likely to
   cause the measurement data to be useless.

   Where a Device has received LLDP messages from multiple adjacent
   nodes, it should provide information extracted from those messages by
   repeating the "lldp" element.





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   An example of an LLDP measurement is shown in Figure 4.  This shows
   an adjacent node (chassis) that is identified by the IP address
   192.0.2.45 (hexadecimal c000022d), and the port on that node is
   numbered using an agent circuit ID [RFC3046] of 162 (hexadecimal a2).

     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2008-04-29T14:33:58">
       <lldp xmlns="urn:ietf:params:xml:ns:geopriv:lm:lldp">
         <chassis type="4">c000022d</chassis>
         <port type="6">a2</port>
       </lldp>
     </measurements>

                    Figure 4: LLDP Measurement Example

   IEEE 802 Devices that are able to obtain information about adjacent
   network switches and their attachment to them by other means MAY use
   this data type to convey this information.

5.2.  DHCP Relay Agent Information Measurements

   The DHCP Relay Agent Information option [RFC3046] provides
   measurement data about the network attachment of a Device.  This
   measurement data can be included in the "dhcp-rai" element.

   The elements in the DHCP relay agent information options are opaque
   data types assigned by the DHCP relay agent.  The three items MAY be
   omitted if unknown: circuit identifier ("circuit", circuit [RFC3046],
   or Interface-Id [RFC3315]), remote identifier ("remote", Remote ID
   [RFC3046], or remote-id [RFC4649]), and subscriber identifier
   ("subscriber", subscriber-id [RFC3993], or Subscriber-ID [RFC4580]).
   The DHCPv6 remote-id has an associated enterprise number
   [IANA.enterprise] as an XML attribute.

     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2008-04-29T14:33:58">
       <dhcp-rai xmlns="urn:ietf:params:xml:ns:geopriv:lm:dhcp">
         <giaddr>192.0.2.158</giaddr>
         <circuit>108b</circuit>
       </dhcp-rai>
     </measurements>

        Figure 5: DHCP Relay Agent Information Measurement Example








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   The "giaddr" element is specified as a dotted quad IPv4 address or an
   RFC 4291 [RFC4291] IPv6 address, using the forms defined in
   [RFC3986]; IPv6 addresses SHOULD use the form described in [RFC5952].
   The enterprise number is specified as a decimal integer.  All other
   information is included verbatim from the DHCP request in hexadecimal
   format.

   The "subscriber" element could be considered sensitive.  This
   information MUST NOT be provided to a LIS that is not authorized to
   receive information about the access network.  See Section 7.1.3 for
   more details.

5.3.  802.11 WLAN Measurements

   In WiFi, or 802.11 [IEEE.80211], networks, a Device might be able to
   provide information about the access point (AP) to which it is
   attached, or other WiFi points it is able to see.  This is provided
   using the "wifi" element, as shown in Figure 6, which shows a single
   complete measurement for a single access point.

     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2011-04-29T14:33:58">
       <wifi xmlns="urn:ietf:params:xml:ns:geopriv:lm:wifi">
         <nicType>Intel(r)PRO/Wireless 2200BG</nicType>
         <ap serving="true">
           <bssid>AB-CD-EF-AB-CD-EF</bssid>
           <ssid>example</ssid>
           <channel>5</channel>
           <location>
             <gml:Point xmlns:gml="http://opengis.net/gml">
               <gml:pos>-34.4 150.8</gml:pos>
             </gml:Point>
           </location>
           <type>a</type>
           <band>5</band>
           <regclass country="AU">2</regclass>
           <antenna>2</antenna>
           <flightTime rmsError="4e-9" samples="1">2.56e-9</flightTime>
           <apSignal>
             <transmit>23</transmit>
             <gain>5</gain>
             <rcpi dBm="true" rmsError="12" samples="1">-59</rcpi>
             <rsni rmsError="15" samples="1">23</rsni>
           </apSignal>
           <deviceSignal>
             <transmit>10</transmit>
             <gain>9</gain>
             <rcpi dBm="true" rmsError="9.5" samples="1">-98.5</rcpi>



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             <rsni rmsError="6" samples="1">7.5</rsni>
           </deviceSignal>
         </ap>
       </wifi>
     </measurements>

                 Figure 6: 802.11 WLAN Measurement Example

   A "wifi" element is made up of one or more access points, and a
   "nicType" element, which MAY be omitted.  Each access point is
   described using the "ap" element, which is comprised of the following
   fields:

   bssid:  The Basic Service Set (BSS) identifier.  In an Infrastructure
      BSS network, the bssid is the 48-bit MAC address of the access
      point.

      The "verified" attribute of this element describes whether the
      Device has verified the MAC address or it authenticated the access
      point or the network operating the access point (for example, a
      captive portal accessed through the access point has been
      authenticated).  This attribute defaults to a value of "false"
      when omitted.

   ssid:  The service set identifier (SSID) for the wireless network
      served by the access point.

      The SSID is a 32-octet identifier that is commonly represented as
      an ASCII [ASCII] or UTF-8 [RFC3629] encoded string.  To represent
      octets that cannot be directly included in an XML element,
      escaping is used.  Sequences of octets that do not represent a
      valid UTF-8 encoding can be escaped using a backslash ('\')
      followed by two case-insensitive hexadecimal digits representing
      the value of a single octet.

      The canonical or value-space form of an SSID is a sequence of up
      to 32 octets that is produced from the concatenation of UTF-8
      encoded sequences of unescaped characters and octets derived from
      escaped components.

   channel:  The channel number (frequency) on which the access point
      operates.

   location:  The location of the access point, as reported by the
      access point.  This element contains any valid location, using the
      rules for a "location-info" element, as described in [RFC5491].





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   type:  The network type for the network access.  This element
      includes the alphabetic suffix of the 802.11 specification that
      introduced the radio interface, or PHY, e.g., "a", "b", "g",
      or "n".

   band:  The frequency band for the radio, in gigahertz (GHz).  802.11
      [IEEE.80211] specifies PHY layers that use 2.4, 3.7, and 5
      gigahertz frequency bands.

   regclass:  The operating class (regulatory domain and class in older
      versions of 802.11); see Annex E of [IEEE.80211].  The "country"
      attribute optionally includes the applicable two-character country
      identifier (dot11CountryString), which can be followed by an 'O',
      'I', or 'X'.  The element text content includes the value of the
      regulatory class: an 8-bit integer in decimal form.

   antenna:  The antenna identifier for the antenna that the access
      point is using to transmit the measured signals.

   flightTime:  Flight time is the difference between the time of
      departure (TOD) of signal from a transmitting station and time of
      arrival (TOA) of signal at a receiving station, as defined in
      [IEEE.80211].  Measurement of this value requires that stations
      synchronize their clocks.  This value can be measured by an access
      point or Device; because the flight time is assumed to be the same
      in either direction -- aside from measurement errors -- only a
      single element is provided.  This element permits the use of the
      "rmsError" and "samples" attributes.  RMS error might be derived
      from the reported RMS error in TOD and TOA.

   apSignal:  Measurement information for the signal transmitted by the
      access point, as observed by the Device.  Some of these values are
      derived from 802.11v [IEEE.80211] messages exchanged between the
      Device and access point.  The contents of this element include:

      transmit:  The transmit power reported by the access point,
         in dBm.

      gain:  The gain of the access point antenna reported by the access
         point, in dB.

      rcpi:  The received channel power indicator for the access point
         signal, as measured by the Device.  This value SHOULD be in
         units of dBm (with RMS error in dB).  If power is measured in a
         different fashion, the "dBm" attribute MUST be set to "false".
         Signal strength reporting on current hardware uses a range of
         different mechanisms; therefore, the value of the "nicType"
         element SHOULD be included if the units are not known to be in



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         dBm, and the value reported by the hardware should be included
         without modification.  This element permits the use of the
         "rmsError" and "samples" attributes.

      rsni:  The received signal-to-noise indicator in dB.  This element
         permits the use of the "rmsError" and "samples" attributes.

   deviceSignal:  Measurement information for the signal transmitted by
      the Device, as reported by the access point.  This element
      contains the same child elements as the "ap" element, with the
      access point and Device roles reversed.

   The only mandatory element in this structure is "bssid".

   The "nicType" element is used to specify the make and model of the
   wireless network interface in the Device.  Different 802.11 chipsets
   report measurements in different ways, so knowing the network
   interface type aids the LIS in determining how to use the provided
   measurement data.  The content of this field is unconstrained, and no
   mechanisms are specified to ensure uniqueness.  This field is
   unlikely to be useful, except under tightly controlled circumstances.

5.3.1.  WiFi Measurement Requests

   Two elements are defined for requesting WiFi measurements in a
   measurement request:

   type:  The "type" element identifies the desired type (or types that
      are requested).

   parameter:  The "parameter" element identifies measurements that are
      requested for each measured access point.  An element is
      identified by its qualified name.  The "context" parameter can be
      used to specify if an element is included as a child of the "ap"
      or "device" elements; omission indicates that it applies to both.

   Multiple types or parameters can be requested by repeating either
   element.

5.4.  Cellular Measurements

   Cellular Devices are common throughout the world, and base station
   identifiers can provide a good source of coarse location information.
   Cellular measurements can be provided to a LIS run by the cellular
   operator, or may be provided to an alternative LIS operator that has
   access to one of several global cell-id to location mapping
   databases.




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   A number of advanced location determination methods have been
   developed for cellular networks.  For these methods, a range of
   measurement parameters can be collected by the network, Device, or
   both in cooperation.  This document includes a basic identifier for
   the wireless transmitter only; future efforts might define additional
   parameters that enable more accurate methods of location
   determination.

   The cellular measurement set allows a Device to report to a LIS any
   LTE (Figure 7), UMTS (Figure 8), GSM (Figure 9), or CDMA (Figure 10)
   cells that it is able to observe.  Cells are reported using their
   global identifiers.  All Third Generation Partnership Project (3GPP)
   cells are identified by a public land mobile network (PLMN), which
   comprises a mobile country code (MCC) and mobile network code (MNC);
   specific fields are added for each network type.

   Formats for 3GPP cell identifiers are described in [TS.3GPP.23.003].
   Bit-level formats for CDMA cell identifiers are described in
   [TIA-2000.5]; decimal representations are used.

   MCC and MNC are provided as decimal digit sequences; a leading zero
   in an MCC or MNC is significant.  All other values are decimal
   integers.

     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2008-04-29T14:33:58">
       <cellular xmlns="urn:ietf:params:xml:ns:geopriv:lm:cell">
         <servingCell>
           <mcc>465</mcc><mnc>20</mnc><eucid>80936424</eucid>
         </servingCell>
         <observedCell>
           <mcc>465</mcc><mnc>06</mnc><eucid>10736789</eucid>
         </observedCell>
       </cellular>
     </measurements>

   Long term evolution (LTE) cells are identified by a 28-bit cell
   identifier (eucid).

                Figure 7: Example LTE Cellular Measurement











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     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2008-04-29T14:33:58">
       <cellular xmlns="urn:ietf:params:xml:ns:geopriv:lm:cell">
         <servingCell>
           <mcc>465</mcc><mnc>20</mnc>
           <rnc>2000</rnc><cid>65000</cid>
         </servingCell>
         <observedCell>
           <mcc>465</mcc><mnc>06</mnc>
           <lac>16383</lac><cid>32767</cid>
         </observedCell>
       </cellular>
     </measurements>

   Universal mobile telephony service (UMTS) cells are identified by a
   12- or 16-bit radio network controller (rnc) id and a 16-bit cell id
   (cid).

                Figure 8: Example UMTS Cellular Measurement


     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2008-04-29T14:33:58">
       <cellular xmlns="urn:ietf:params:xml:ns:geopriv:lm:cell">
         <servingCell>
           <mcc>465</mcc><mnc>06</mnc>
           <lac>16383</lac><cid>32767</cid>
         </servingCell>
       </cellular>
     </measurements>

   Global System for Mobile communication (GSM) cells are identified by
   a 16-bit location area code (lac) and a 16-bit cell id (cid).

                Figure 9: Example GSM Cellular Measurement
















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     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2008-04-29T14:33:58">
       <cellular xmlns="urn:ietf:params:xml:ns:geopriv:lm:cell">
         <servingCell>
           <sid>15892</sid><nid>4723</nid><baseid>12</baseid>
         </servingCell>
         <observedCell>
           <sid>15892</sid><nid>4723</nid><baseid>13</baseid>
         </observedCell>
       </cellular>
     </measurements>

   Code division multiple access (CDMA) cells are not identified by a
   PLMN; instead, these use a 15-bit system id (sid), a 16-bit network
   id (nid), and a 16-bit base station id (baseid).

               Figure 10: Example CDMA Cellular Measurement

   In general, a cellular Device will be attached to the cellular
   network, so the notion of a serving cell exists.  Cellular networks
   also provide overlap between neighboring sites, so a mobile Device
   can hear more than one cell.  The measurement schema supports sending
   both the serving cell and any other cells that the mobile might be
   able to hear.  In some cases, the Device could simply be listening to
   cell information without actually attaching to the network; mobiles
   without a SIM are an example of this.  In this case, the Device could
   report cells it can hear without identifying any particular cell as a
   serving cell.  An example of this is shown in Figure 11.

     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2008-04-29T14:33:58">
       <cellular xmlns="urn:ietf:params:xml:ns:geopriv:lm:cell">
         <observedCell>
           <mcc>465</mcc><mnc>20</mnc>
           <rnc>2000</rnc><cid>65000</cid>
         </observedCell>
         <observedCell>
           <mcc>465</mcc><mnc>06</mnc>
           <lac>16383</lac><cid>32767</cid>
         </observedCell>
       </cellular>
     </measurements>

             Figure 11: Example Observed Cellular Measurement







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5.4.1.  Cellular Measurement Requests

   Two elements can be used in measurement requests for cellular
   measurements:

   type:  A label indicating the type of identifier to provide: one of
      "gsm", "umts", "lte", or "cdma".

   network:  The network portion of the cell identifier.  For 3GPP
      networks, this is the combination of MCC and MNC; for CDMA, this
      is the network identifier.

   Multiple identifier types or networks can be identified by repeating
   either element.

5.5.  GNSS Measurements

   A Global Navigation Satellite System (GNSS) uses orbiting satellites
   to transmit signals.  A Device with a GNSS receiver is able to take
   measurements from the satellite signals.  The results of these
   measurements can be used to determine time and the location of the
   Device.

   Determining location and time in autonomous GNSS receivers follows
   three steps:

   Signal acquisition:  During the signal acquisition stage, the
      receiver searches for the repeating code that is sent by each GNSS
      satellite.  Successful operation typically requires measurement
      data for a minimum of 5 satellites.  At this stage, measurement
      data is available to the Device.

   Navigation message decode:  Once the signal has been acquired, the
      receiver then receives information about the configuration of the
      satellite constellation.  This information is broadcast by each
      satellite and is modulated with the base signal at a low rate; for
      instance, GPS sends this information at about 50 bits per second.

   Calculation:  The measurement data is combined with the data on the
      satellite constellation to determine the location of the receiver
      and the current time.

   A Device that uses a GNSS receiver is able to report measurements
   after the first stage of this process.  A LIS can use the results of
   these measurements to determine a location.  In the case where there
   are fewer results available than the optimal minimum, the LIS might
   be able to use other sources of measurement information and combine
   these with the available measurement data to determine a position.



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      Note: The use of different sets of GNSS assistance data can reduce
      the amount of time required for the signal acquisition stage and
      obviate the need for the receiver to extract data on the satellite
      constellation.  Provision of assistance data is outside the scope
      of this document.

   Figure 12 shows an example of GNSS measurement data.  The measurement
   shown is for the GPS satellite system and includes measurement data
   for three satellites only.

     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2008-04-29T14:33:58" timeError="2e-5">
       <gnss xmlns="urn:ietf:params:xml:ns:geopriv:lm:gnss"
         system="gps" signal="L1">
         <sat num="19">
           <doppler>499.9395</doppler>
           <codephase rmsError="1.6e-9">0.87595747</codephase>
           <cn0>45</cn0>
         </sat>
         <sat num="27">
           <doppler>378.2657</doppler>
           <codephase rmsError="1.6e-9">0.56639479</codephase>
           <cn0>52</cn0>
         </sat>
         <sat num="20">
           <doppler>-633.0309</doppler>
           <codephase rmsError="1.6e-9">0.57016835</codephase>
           <cn0>48</cn0>
         </sat>
       </gnss>
     </measurements>

                    Figure 12: Example GNSS Measurement

   Each "gnss" element represents a single set of GNSS measurement data,
   taken at a single point in time.  Measurements taken at different
   times can be included in different "gnss" elements to enable
   iterative refinement of results.

   GNSS measurement parameters are described in more detail in the
   following sections.

5.5.1.  GNSS: System Type and Signal

   The GNSS measurement structure is designed to be generic and to apply
   to different GNSS types.  Different signals within those systems are
   also accounted for and can be measured separately.




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   The GNSS type determines the time system that is used.  An indication
   of the type of system and signal can ensure that the LIS is able to
   correctly use measurements.

   Measurements for multiple GNSS types and signals can be included by
   repeating the "gnss" element.

   This document creates an IANA registry for GNSS types.  Two satellite
   systems are registered by this document: GPS [GPS.ICD] and Galileo
   [Galileo.ICD].  Details for the registry are included in Section 9.1.

5.5.2.  Time

   Each set of GNSS measurements is taken at a specific point in time.
   The "time" attribute is used to indicate the time that the
   measurement was acquired, if the receiver knows how the time system
   used by the GNSS relates to UTC time.

   Alternative to (or in addition to) the measurement time, the
   "gnssTime" element MAY be included.  The "gnssTime" element includes
   a relative time in milliseconds using the time system native to the
   satellite system.  For the GPS satellite system, the "gnssTime"
   element includes the time of week in milliseconds.  For the Galileo
   system, the "gnssTime" element includes the time of day in
   milliseconds.

   The accuracy of the time measurement provided is critical in
   determining the accuracy of the location information derived from
   GNSS measurements.  The receiver SHOULD indicate an estimated time
   error for any time that is provided.  An RMS error can be included
   for the "gnssTime" element, with a value in milliseconds.

5.5.3.  Per-Satellite Measurement Data

   Multiple satellites are included in each set of GNSS measurements
   using the "sat" element.  Each satellite is identified by a number in
   the "num" attribute.  The satellite number is consistent with the
   identifier used in the given GNSS.

   Both the GPS and Galileo systems use satellite numbers between 1
   and 64.

   The GNSS receiver measures the following parameters for each
   satellite:

   doppler:  The observed Doppler shift of the satellite signal,
      measured in meters per second.  This is converted from a value in
      Hertz by the receiver to allow the measurement to be used without



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      knowledge of the carrier frequency of the satellite system.  This
      value permits the use of RMS error attributes, also measured in
      meters per second.

   codephase:  The observed code phase for the satellite signal,
      measured in milliseconds.  This is converted from the system-
      specific value of chips or wavelengths into a system-independent
      value.  Larger values indicate larger distances from satellite to
      receiver.  This value permits the use of RMS error attributes,
      also measured in milliseconds.

   cn0:  The signal-to-noise ratio for the satellite signal, measured in
      decibel-Hertz (dB-Hz).  The expected range is between 20 and
      50 dB-Hz.

   mp:  An estimation of the amount of error that multipath signals
      contribute in meters.  This parameter MAY be omitted.

   cq:  An indication of the carrier quality.  Two attributes are
      included: "continuous" (which can be either "true" or "false") and
      "direct" (which can be either "direct" or "inverted").  This
      parameter MAY be omitted.

   adr:  The accumulated Doppler range, measured in meters.  This
      parameter MAY be omitted and is not useful unless multiple sets of
      GNSS measurements are provided or differential positioning is
      being performed.

   All values are converted from measures native to the satellite system
   to generic measures to ensure consistency of interpretation.  Unless
   necessary, the schema does not constrain these values.

5.5.4.  GNSS Measurement Requests

   Measurement requests can include a "gnss" element, which includes the
   "system" and "signal" attributes.  Multiple elements can be included
   to indicate requests for GNSS measurements from multiple systems or
   signals.

5.6.  DSL Measurements

   Digital Subscriber Line (DSL) networks rely on a range of network
   technologies.  DSL deployments regularly require cooperation between
   multiple organizations.  These fall into two broad categories:
   infrastructure providers and Internet service providers (ISPs).  For
   the same end user, an infrastructure and Internet service can be
   provided by different entities.  Infrastructure providers manage the
   bulk of the physical infrastructure, including cabling.  End users



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   obtain their service from an ISP, which manages all aspects visible
   to the end user, including IP address allocation and operation of a
   LIS.  See [DSL.TR025] and [DSL.TR101] for further information on DSL
   network deployments and the parameters that are available.

   Exchange of measurement information between these organizations is
   necessary for location information to be correctly generated.  The
   ISP LIS needs to acquire location information from the infrastructure
   provider.  However, since the infrastructure provider could have no
   knowledge of Device identifiers, it can only identify a stream of
   data that is sent to the ISP.  This is resolved by passing
   measurement data relating to the Device to a LIS operated by the
   infrastructure provider.

5.6.1.  L2TP Measurements

   The Layer 2 Tunneling Protocol (L2TP) [RFC2661] is a common means of
   linking the infrastructure provider and the ISP.  The infrastructure
   provider LIS requires measurement data that identifies a single L2TP
   tunnel, from which it can generate location information.  Figure 13
   shows an example L2TP measurement.

     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2008-04-29T14:33:58">
       <dsl xmlns="urn:ietf:params:xml:ns:geopriv:lm:dsl">
         <l2tp>
           <src>192.0.2.10</src>
           <dest>192.0.2.61</dest>
           <session>528</session>
         </l2tp>
       </dsl>
     </measurements>

                  Figure 13: Example DSL L2TP Measurement

5.6.2.  RADIUS Measurements

   When authenticating network access, the infrastructure provider might
   employ a RADIUS [RFC2865] proxy at the DSL Access Module (DSLAM) or
   Access Node (AN).  These messages provide the ISP RADIUS server with
   an identifier for the DSLAM or AN, plus the slot and port to which
   the Device is attached.  These data can be provided as a measurement
   that allows the infrastructure provider LIS to generate location
   information.







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   The format of the AN, slot, and port identifiers is not defined in
   the RADIUS protocol.  The slot and port together identify a circuit
   on the AN, analogous to the circuit identifier in [RFC3046].  These
   items are provided directly, as they would be in the RADIUS message.
   An example is shown in Figure 14.

     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2008-04-29T14:33:58">
       <dsl xmlns="urn:ietf:params:xml:ns:geopriv:lm:dsl">
         <an>AN-7692</an>
         <slot>3</slot>
         <port>06</port>
       </dsl>
     </measurements>

                 Figure 14: Example DSL RADIUS Measurement

5.6.3.  Ethernet VLAN Tag Measurements

   For Ethernet-based DSL access networks, the DSLAM or AN provides two
   VLAN tags on packets.  A C-TAG is used to identify the incoming
   residential circuit, while the S-TAG is used to identify the DSLAM or
   AN.  The C-TAG and S-TAG together can be used to identify a single
   point of network attachment.  An example is shown in Figure 15.

     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2008-04-29T14:33:58">
       <dsl xmlns="urn:ietf:params:xml:ns:geopriv:lm:dsl">
         <stag>613</stag>
         <ctag>1097</ctag>
       </dsl>
     </measurements>

                Figure 15: Example DSL VLAN Tag Measurement

   Alternatively, the C-TAG can be replaced by data on the slot and port
   to which the Device is attached.  This information might be included
   in RADIUS requests that are proxied from the infrastructure provider
   to the ISP RADIUS server.












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5.6.4.  ATM Virtual Circuit Measurements

   An ATM virtual circuit can be employed between the ISP and
   infrastructure provider.  Providing the virtual port ID (VPI) and
   virtual circuit ID (VCI) for the virtual circuit gives the
   infrastructure provider LIS the ability to identify a single data
   stream.  A sample measurement is shown in Figure 16.

     <measurements xmlns="urn:ietf:params:xml:ns:geopriv:lm"
           time="2008-04-29T14:33:58">
       <dsl xmlns="urn:ietf:params:xml:ns:geopriv:lm:dsl">
         <vpi>55</vpi>
         <vci>6323</vci>
       </dsl>
     </measurements>

                  Figure 16: Example DSL ATM Measurement

6.  Privacy Considerations

   Location-related measurement data can be as privacy sensitive as
   location information [RFC6280].

   Measurement data is effectively equivalent to location information if
   the contextual knowledge necessary to generate one from the other is
   readily accessible.  Even where contextual knowledge is difficult to
   acquire, there can be no assurance that an authorized recipient of
   the contextual knowledge is also authorized to receive location
   information.

   In order to protect the privacy of the subject of location-related
   measurement data, measurement data MUST be protected with the same
   degree of protection as location information.  The confidentiality
   and authentication provided by Transport Layer Security (TLS) MUST be
   used in order to convey measurement data over HELD [RFC5985].  Other
   protocols MUST provide comparable guarantees.

6.1.  Measurement Data Privacy Model

   It is not necessary to distribute measurement data in the same
   fashion as location information.  Measurement data is less useful to
   location recipients than location information.  A simple distribution
   model is described in this document.








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   In this simple model, the Device is the only entity that is able to
   distribute measurement data.  To use an analogy from the GEOPRIV
   architecture, the Device -- as the Location Generator or the
   Measurement Data Generator -- is the sole entity that can act in the
   role of both Rule Maker and Location Server.

   A Device that provides location-related measurement data MUST only do
   so as explicitly authorized by a Rule Maker.  This depends on having
   an interface that allows Rule Makers (for instance, users or
   administrators) to control where and how measurement data is
   provided.

   No entity is permitted to redistribute measurement data.  The Device
   directs other entities regarding how measurement data is used and
   retained.

   The GEOPRIV model [RFC6280] protects the location of a Target using
   direction provided by a Rule Maker.  For the purposes of measurement
   data distribution, this model relies on the assumptions made in
   Section 3 of HELD [RFC5985].  These assumptions effectively declare
   the Device to be a proxy for both Target and Rule Maker.

6.2.  LIS Privacy Requirements

   A LIS MUST NOT reveal location-related measurement data to any other
   entity.  A LIS MUST NOT reveal location information based on
   measurement data to any other entity unless directed to do so by the
   Device.

   By adding measurement data to a request for location information, the
   Device implicitly grants permission for the LIS to generate the
   requested location information using the measurement data.
   Permission to use this data for any other purpose is not implied.

   As long as measurement data is only used in serving the request that
   contains it, rules regarding data retention are not necessary.  A LIS
   MUST discard location-related measurement data after servicing a
   request, unless the Device grants permission to use that information
   for other purposes.

6.3.  Measurement Data and Location URIs

   A LIS MAY use measurement data provided by the Device to serve
   requests to location URIs, if the Device permits it.  A Device
   permits this by including measurement data in a request that
   explicitly requests a location URI.  By requesting a location URI,





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   the Device grants permission for the LIS to use the measurement data
   in serving requests to that location URI.  The LIS cannot provide
   location recipients with measurement data, as defined in Section 6.1.

      Note: In HELD, the "any" type is not an explicit request for a
      location URI, though a location URI might be provided.

   The usefulness of measurement data that is provided in this fashion
   is limited.  The measurement data is only valid at the time that it
   was acquired by the Device.  At the time that a request is made to a
   location URI, the Device might have moved, rendering the measurement
   data incorrect.

   A Device is able to explicitly limit the time that a LIS retains
   measurement data by adding an expiry time to the measurement data.  A
   LIS MUST NOT retain location-related measurement data in memory,
   storage, or logs beyond the time indicated in the "expires" attribute
   (Section 4.1.2).  A LIS MUST NOT retain measurement data if the
   "expires" attribute is absent.

6.4.  Measurement Data Provided by a Third Party

   An authorized third-party request for the location of a Device (see
   [RFC6155]) can include location-related measurement data.  This is
   possible where the third party is able to make observations about the
   Device.

   A third party that provides measurement data MUST be authorized to
   provide the specific measurement for the identified Device.  Either a
   third party MUST be trusted by the LIS for the purposes of providing
   measurement data of the provided type, or the measurement data MUST
   be validated (see Section 7.2.1) before being used.

   How a third party authenticates its identity or gains authorization
   to use measurement data is not covered by this document.

7.  Security Considerations

   The use of location-related measurement data has privacy
   considerations that are discussed in Section 6.

7.1.  Threat Model

   The threat model for location-related measurement data concentrates
   on the Device providing falsified, stolen, or incorrect measurement
   data.





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   A Device that provides location-related measurement data might use
   data to:

   o  acquire the location of another Device, without authorization;

   o  extract information about network topology; or

   o  coerce the LIS into providing falsified location information based
      on the measurement data.

   Location-related measurement data describes the physical environment
   or network attachment of a Device.  A third-party adversary in the
   proximity of the Device might be able to alter the physical
   environment such that the Device provides measurement data that is
   controlled by the third party.  This might be used to indirectly
   control the location information that is derived from measurement
   data.

7.1.1.  Acquiring Location Information without Authorization

   Requiring authorization for location requests is an important part of
   privacy protections of a location protocol.  A location configuration
   protocol usually operates under a restricted policy that allows a
   requester to obtain their own location.  HELD identity extensions
   [RFC6155] allow other entities to be authorized, conditional on a
   Rule Maker providing sufficient authorization.

   The intent of these protections is to ensure that a location
   recipient is authorized to acquire location information.  Location-
   related measurement data could be used by an attacker to circumvent
   such authorization checks if the association between measurement data
   and Target Device is not validated by a LIS.

   A LIS can be coerced into providing location information for a Device
   that a location recipient is not authorized to receive.  A request
   identifies one Device (implicitly or explicitly), but measurement
   data is provided for another Device.  If the LIS does not check that
   the measurement data is for the identified Device, it could
   incorrectly authorize the request.

   By using unverified measurement data to generate a response, the LIS
   provides information about a Device without appropriate
   authorization.

   The feasibility of this attack depends on the availability of
   information that links a Device with measurement data.  In some
   cases, measurement data that is correlated with a Target is readily
   available.  For instance, LLDP measurements (Section 5.1) are



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   broadcast to all nodes on the same network segment.  An attacker on
   that network segment can easily gain measurement data that relates a
   Device with measurements.

   For some types of measurement data, it's necessary for an attacker to
   know the location of the Target in order to determine what
   measurements to use.  This attack is meaningless for types of
   measurement data that require that the attacker first know the
   location of the Target before measurement data can be acquired or
   fabricated.  GNSS measurements (Section 5.5) share this trait with
   many wireless location determination methods.

7.1.2.  Extracting Network Topology Data

   Allowing requests with measurements might be used to collect
   information about network topology.

   Network topology can be considered sensitive information by a network
   operator for commercial or security reasons.  While it is impossible
   to completely prevent a Device from acquiring some knowledge of
   network topology if a location service is provided, a network
   operator might desire to limit how much of this information is made
   available.

   Mapping a network topology does not require that an attacker be able
   to associate measurement data with a particular Device.  If a
   requester is able to try a number of measurements, it is possible to
   acquire information about network topology.

   It is not even necessary that the measurements are valid; random
   guesses are sufficient, provided that there is no penalty or cost
   associated with attempting to use the measurements.

7.1.3.  Exposing Network Topology Data

   A Device could reveal information about a network to entities outside
   of that network if it provides location measurement data to a LIS
   that is outside of that network.  With the exception of GNSS
   measurements, the measurements in this document provide information
   about an access network that could reveal topology information to an
   unauthorized recipient.

   A Device MUST NOT provide information about network topology without
   a clear signal that the recipient is authorized.  A LIS that is
   discovered using DHCP as described in LIS discovery [RFC5986] can be
   considered to be authorized to receive information about the access
   network.




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7.1.4.  Lying by Proxy

   Location information, which includes measurement data, is a function
   of its inputs.  Thus, falsified measurement data can be used to alter
   the location information that is provided by a LIS.

   Some types of measurement data are relatively easy to falsify in a
   way that causes the resulting location information to be selected
   with little or no error.  For instance, GNSS measurements are easy to
   use for this purpose because all the contextual information necessary
   to calculate a position using measurements is broadcast by the
   satellites [HARPER].

   An attacker that falsifies measurement data gains little if they are
   the only recipient of the result.  The attacker knows that the
   location information is bad.  The attacker only gains if the
   information can somehow be attributed to the LIS by another location
   recipient.  By coercing the LIS into providing falsified location
   information, any credibility that the LIS might have -- that the
   attacker does not -- is gained by the attacker.

   A third party that is reliant on the integrity of the location
   information might base an evaluation of the credibility of the
   information on the source of the information.  If that third party is
   able to attribute location information to the LIS, then an attacker
   might gain.

   Location information that is provided to the Device without any means
   to identify the LIS as its source is not subject to this attack.  The
   Device is identified as the source of the data when it distributes
   the location information to location recipients.

   Location information is attributed to the LIS either through the use
   of digital signatures or by having the location recipient directly
   interact with the LIS.  A LIS that digitally signs location
   information becomes identifiable as the source of the data.
   Similarly, the LIS is identified as a source of data if a location
   recipient acquires information directly from a LIS using a
   location URI.

7.1.5.  Measurement Replay

   The values of some measured properties do not change over time for a
   single location.  The time invariance of network properties is often
   a direct result of the practicalities of operating the network.
   Limiting the changes to a network ensures greater consistency of
   service.  A largely static network also greatly simplifies the data
   management tasks involved with providing a location service.



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   However, time-invariant properties allow for simple replay attacks,
   where an attacker acquires measurements that can later be used
   without being detected as being invalid.

   Measurement data is frequently an observation of a time-invariant
   property of the environment at the subject location.  For
   measurements of this nature, nothing in the measurement itself is
   sufficient proof that the Device is present at the resulting
   location.  Measurement data might have been previously acquired and
   reused.

   For instance, the identity of a radio transmitter, if broadcast by
   that transmitter, can be collected and stored.  An attacker that
   wishes it known that they exist at a particular location can claim to
   observe this transmitter at any time.  Nothing inherent in the claim
   reveals it to be false.

7.1.6.  Environment Spoofing

   Some types of measurement data can be altered or influenced by a
   third party so that a Device unwittingly provides falsified data.  If
   it is possible for a third party to alter the measured phenomenon,
   then any location information that is derived from this data can be
   indirectly influenced.

   Altering the environment in this fashion might not require
   involvement with either a Device or LIS.  Measurement that is passive
   -- where the Device observes a signal or other phenomenon without
   direct interaction -- is most susceptible to alteration by third
   parties.

   Measurement of radio signal characteristics is especially vulnerable,
   since an adversary need only be in the general vicinity of the Device
   and be able to transmit a signal.  For instance, a GNSS spoofer is
   able to produce fake signals that claim to be transmitted by any
   satellite or set of satellites (see [GPS.SPOOF]).

   Measurements that require direct interaction increase the complexity
   of the attack.  For measurements relating to the communication
   medium, a third party cannot avoid direct interaction; they need only
   be on the communications path (that is, man in the middle).

   Even if the entity that is interacted with is authenticated, this
   does not provide any assurance about the integrity of measurement
   data.  For instance, the Device might authenticate the identity of a
   radio transmitter through the use of cryptographic means and obtain
   signal strength measurements for that transmitter.  Radio signal




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   strength is trivial for an attacker to increase simply by receiving
   and amplifying the raw signal; it is not necessary for the attacker
   to be able to understand the signal content.

      Note: This particular "attack" is more often completely
      legitimate.  Radio repeaters are a commonplace mechanism used to
      increase radio coverage.

   Attacks that rely on altering the observed environment of a Device
   require countermeasures that affect the measurement process.  For
   radio signals, countermeasures could include the use of authenticated
   signals, or altered receiver design.  In general, countermeasures are
   highly specific to the individual measurement process.  An exhaustive
   discussion of these issues is left to the relevant literature for
   each measurement technology.

   A Device that provides measurement data is assumed to be responsible
   for applying appropriate countermeasures against this type of attack.

   Where a Device is the sole recipient of location information derived
   from measurement data, a LIS might choose to provide location
   information without any validation.  The responsibility for ensuring
   the veracity of the measurement data lies with the Device.

   Measurement data that is susceptible to this sort of influence SHOULD
   be treated as though it were produced by an untrusted Device for
   those cases where a location recipient might attribute the location
   information to the LIS.  GNSS measurements and radio signal strength
   measurements can be affected relatively cheaply, though almost all
   other measurement types can be affected with varying costs to an
   attacker, with the largest cost often being a requirement for
   physical access.  To the extent that it is feasible, measurement data
   SHOULD be subjected to the same validation as for other types of
   attacks that rely on measurement falsification.

      Note: Altered measurement data might be provided by a Device that
      has no knowledge of the alteration.  Thus, an otherwise trusted
      Device might still be an unreliable source of measurement data.

7.2.  Mitigation

   The following measures can be applied to limit or prevent attacks.
   The effectiveness of each depends on the type of measurement data and
   how that measurement data is acquired.







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   Two general approaches are identified for dealing with untrusted
   measurement data:

   1.  Require independent validation of measurement data or the
       location information that is produced.

   2.  Identify the types of sources that provided the measurement data
       from which that location information was derived.

   This section goes into more detail on the different forms of
   validation in Sections 7.2.1, 7.2.2, and 7.2.3.  The impact of
   attributing location information to sources is discussed in more
   detail in Section 7.2.4.

   Any costs in validation are balanced against the degree of integrity
   desired from the resulting location information.

7.2.1.  Measurement Validation

   Recognizing that measurement data has been falsified is difficult in
   the absence of integrity mechanisms.

   Independent confirmation of the veracity of measurement data ensures
   that the measurement is accurate and that it applies to the correct
   Device.  When it's possible to gather the same measurement data from
   a trusted and independent source without undue expense, the LIS can
   use the trusted data in place of what the untrusted Device has sent.
   In cases where that is impractical, the untrusted data can provide
   hints that allow corroboration of the data (see Section 7.2.1.1).

   Measurement information might not contain any inherent indication
   that it is falsified.  In addition, it can be difficult to obtain
   information that would provide any degree of assurance that the
   measurement device is physically at any particular location.
   Measurements that are difficult to verify require other forms of
   assurance before they can be used.

7.2.1.1.  Effectiveness

   Measurement validation MUST be used if measurement data for a
   particular Device can be easily acquired by unauthorized location
   recipients, as described in Section 7.1.1.  This prevents
   unauthorized access to location information using measurement data.

   Validation of measurement data can be significantly more effective
   than independent acquisition of the same.  For instance, a Device in
   a large Ethernet network could provide a measurement indicating its
   point of attachment using LLDP measurements.  For a LIS, acquiring



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   the same measurement data might require a request to all switches in
   that network.  With the measurement data, validation can target the
   identified switch with a specific query.

   Validation is effective in identifying falsified measurement data
   (Section 7.1.4), including attacks involving replay of measurement
   data (Section 7.1.5).  Validation also limits the amount of network
   topology information (Section 7.1.2) made available to Devices to
   that portion of the network topology to which they are directly
   attached.

   Measurement validation has no effect if the underlying environment is
   being altered (Section 7.1.6).

7.2.1.2.  Limitations (Unique Observer)

   A Device is often in a unique position to make a measurement.  It
   alone occupies the point in space-time that the location
   determination process seeks to determine.  The Device becomes a
   unique observer for a particular property.

   The ability of the Device to become a unique observer makes the
   Device invaluable to the location determination process.  As a unique
   observer, it also makes the claims of a Device difficult to validate
   and easy to spoof.

   As long as no other entity is capable of making the same
   measurements, there is also no other entity that can independently
   check that the measurements are correct and applicable to the Device.
   A LIS might be unable to validate all or part of the measurement data
   it receives from a unique observer.  For instance, a signal strength
   measurement of the signal from a radio tower cannot be validated
   directly.

   Some portion of the measurement data might still be independently
   verified, even if all information cannot.  In the previous example,
   the radio tower might be able to provide verification that the Device
   is present if it is able to observe a radio signal sent by the
   Device.

   If measurement data can only be partially validated, the extent to
   which it can be validated determines the effectiveness of validation
   against these attacks.








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   The advantage of having the Device as a unique observer is that it
   makes it difficult for an attacker to acquire measurements without
   the assistance of the Device.  Attempts to use measurements to gain
   unauthorized access to measurement data (Section 7.1.1) are largely
   ineffectual against a unique observer.

7.2.2.  Location Validation

   Location information that is derived from location-related
   measurement data can also be verified against trusted location
   information.  Rather than validating inputs to the location
   determination process, suspect locations are identified at the output
   of the process.

   Trusted location information is acquired using sources of measurement
   data that are trusted.  Untrusted location information is acquired
   using measurement data provided from untrusted sources, which might
   include the Device.  These two locations are compared.  If the
   untrusted location agrees with the trusted location, the untrusted
   location information is used.

   Algorithms for the comparison of location information are not
   included in this document.  However, a simple comparison for
   agreement might require that the untrusted location be entirely
   contained within the uncertainty region of the trusted location.

   There is little point in using a less accurate, less trusted
   location.  Untrusted location information that has worse accuracy
   than trusted information can be immediately discarded.  There are
   multiple factors that affect accuracy, uncertainty and currency being
   the most important.  How location information is compared for
   accuracy is not defined in this document.

7.2.2.1.  Effectiveness

   Location validation limits the extent to which falsified -- or
   erroneous -- measurement data can cause an incorrect location to be
   reported.

   Location validation can be more efficient than validation of inputs,
   particularly for a unique observer (Section 7.2.1.2).

   Validating location ensures that the Device is at or near the
   resulting location.  Location validation can be used to limit or
   prevent all of the attacks identified in this document.






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7.2.2.2.  Limitations

   The trusted location that is used for validation is always less
   accurate than the location that is being checked.  The amount by
   which the untrusted location is more accurate, is the same amount
   that an attacker can exploit.

   For example, a trusted location might indicate an uncertainty region
   with a radius of five kilometers.  An untrusted location that
   describes a 100-meter uncertainty within the larger region might be
   accepted as more accurate.  An attacker might still falsify
   measurement data to select any location within the larger uncertainty
   region.  While the 100-meter uncertainty that is reported seems more
   accurate, a falsified location could be anywhere in the
   five-kilometer region.

   Where measurement data might have been falsified, the actual
   uncertainty is effectively much higher.  Local policy might allow
   differing degrees of trust to location information derived from
   untrusted measurement data.  This might be a boolean operation with
   only two possible outcomes: untrusted location information might be
   used entirely or not at all.  Alternatively, untrusted location
   information could be combined with trusted location information using
   different weightings, based on a value set in local policy.

7.2.3.  Supporting Observations

   Replay attacks using previously acquired measurement data are
   particularly hard to detect without independent validation.  Rather
   than validate the measurement data directly, supplementary data might
   be used to validate measurements or the location information derived
   from those measurements.

   These supporting observations could be used to convey information
   that provides additional assurance that measurement data from the
   Device was acquired at a specific time and place.  In effect, the
   Device is requested to provide proof of its presence at the resulting
   location.

   For instance, a Device that measures attributes of a radio signal
   could also be asked to provide a sample of the measured radio signal.
   If the LIS is able to observe the same signal, the two observations
   could be compared.  Providing that the signal cannot be predicted in
   advance by the Device, this could be used to support the claim that
   the Device is able to receive the signal.  Thus, the Device is likely
   to be within the range that the signal is transmitted.  A LIS could
   use this to attribute a higher level of trust in the associated
   measurement data or resulting location.



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7.2.3.1.  Effectiveness

   The use of supporting observations is limited by the ability of the
   LIS to acquire and validate these observations.  The advantage of
   selecting observations independent of measurement data is that
   observations can be selected based on how readily available the data
   is for both LIS and Device.  The amount and quality of the data can
   be selected based on the degree of assurance that is desired.

   The use of supporting observations is similar to both measurement
   validation and location validation.  All three methods rely on
   independent validation of one or more properties.  The applicability
   of each method is similar.

   The use of supporting observations can be used to limit or prevent
   all of the attacks identified in this document.

7.2.3.2.  Limitations

   The effectiveness of the validation method depends on the quality of
   the supporting observation: how hard it is for the entity performing
   the validation to obtain the data at a different time or place, how
   difficult it is to guess, and what other costs might be involved in
   acquiring this data.

   In the example of an observed radio signal, requesting a sample of
   the signal only provides an assurance that the Device is able to
   receive the signal transmitted by the measured radio transmitter.
   This only provides some assurance that the Device is within range of
   the transmitter.

   As with location validation, a Device might still be able to provide
   falsified measurements that could alter the value of the location
   information as long as the result is within this region.

   Requesting additional supporting observations can reduce the size of
   the region over which location information can be altered by an
   attacker, or increase trust in the result, but each additional
   measurement imposes an acquisition cost.  Supporting observations
   contribute little or nothing toward the primary goal of determining
   the location of the Device.

7.2.4.  Attribution

   Lying by proxy (Section 7.1.4) relies on the location recipient being
   able to attribute location information to a LIS.  The effectiveness
   of this attack is negated if location information is explicitly
   attributed to a particular source.



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   This requires an extension to the location object that explicitly
   identifies the source (or sources) of each item of location
   information.

   Rather than relying on a process that seeks to ensure that location
   information is accurate, this approach instead provides a location
   recipient with the information necessary to reach their own
   conclusion about the trustworthiness of the location information.

   Including an authenticated identity for all sources of measurement
   data presents a number of technical and operational challenges.  It
   is possible that the LIS has a transient relationship with a Device.
   A Device is not expected to share authentication information with a
   LIS.  There is no assurance that Device identification is usable by a
   potential location recipient.  Privacy concerns might also prevent
   the sharing of identification information, even if it were available
   and usable.

   Identifying the type of measurement source allows a location
   recipient to make a decision about the trustworthiness of location
   information without depending on having authenticated identity
   information for each source.  An element for this purpose is defined
   in Section 4.4.

   When including location information that is based on measurement data
   from sources that might be untrusted, a LIS SHOULD include
   alternative location information that is derived from trusted sources
   of measurement data.  Each item of location information can then be
   labeled with the source of that data.

   A location recipient that is able to identify a specific source of
   measurement data (whether it be LIS or Device) can use this
   information to attribute location information to either entity or to
   both entities.  The location recipient is then better able to make
   decisions about trustworthiness based on the source of the data.

   A location recipient that does not understand the "source" element is
   unable to make this distinction.  When constructing a PIDF-LO
   document, trusted location information MUST be placed in the PIDF-LO
   so that it is given higher priority to any untrusted location
   information according to Rule #8 of [RFC5491].

   Attribution of information does nothing to address attacks that alter
   the observed parameters that are used in location determination
   (Section 7.1.6).






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7.2.5.  Stateful Correlation of Location Requests

   Stateful examination of requests can be used to prevent a Device from
   attempting to map network topology using requests for location
   information (Section 7.1.2).

   Simply limiting the rate of requests from a single Device reduces the
   amount of data that a Device can acquire about network topology.  A
   LIS could also make observations about the movements of a Device.  A
   Device that is attempting to gather topology information is likely to
   be assigned a location that changes significantly between subsequent
   requests, possibly violating physical laws (or lower limits that
   might still be unlikely) with respect to speed and acceleration.

7.3.  An Unauthorized or Compromised LIS

   A compromised LIS, or a compromise in LIS discovery [RFC5986], could
   lead to an unauthorized entity obtaining measurement data.  This
   information could then be used or redistributed.  A Device MUST
   ensure that it authenticates a LIS, as described in Section 9 of
   [RFC5985].

   An entity that is able to acquire measurement data can, in addition
   to using those measurements to learn the location of a Device, also
   use that information for other purposes.  This information can be
   used to provide insight into network topology (Section 7.1.2).

   Measurement data might also be exploited in other ways.  For example,
   revealing the type of 802.11 transceiver that a Device uses could
   allow an attacker to use specific vulnerabilities to attack a Device.
   Similarly, revealing information about network elements could enable
   targeted attacks on that infrastructure.

8.  Measurement Schemas

   The schemas are broken up into their respective functions.  A base
   container schema into which all measurements are placed is defined,
   including the definition of a measurement request (Section 8.1).  A
   PIDF-LO extension is defined in a separate schema (Section 8.2).  A
   basic Types Schema contains common definitions, including the
   "rmsError" and "samples" attributes, plus types for IPv4, IPv6, and
   MAC addresses (Section 8.3).  Each of the specific measurement types
   is defined in a separate schema.








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8.1.  Measurement Container Schema

   <?xml version="1.0"?>
   <xs:schema
       xmlns:lm="urn:ietf:params:xml:ns:geopriv:lm"
       xmlns:bt="urn:ietf:params:xml:ns:geopriv:lm:basetypes"
       xmlns:xs="http://www.w3.org/2001/XMLSchema"
       targetNamespace="urn:ietf:params:xml:ns:geopriv:lm"
       elementFormDefault="qualified"
       attributeFormDefault="unqualified">

     <xs:annotation>
       <xs:appinfo
           source="urn:ietf:params:xml:schema:geopriv:lm">
       </xs:appinfo>
       <xs:documentation
           source="http://www.rfc-editor.org/rfc/rfc7105.txt">
           This schema defines a framework for location measurements.
       </xs:documentation>
     </xs:annotation>

    <xs:import namespace="urn:ietf:params:xml:ns:geopriv:lm:basetypes"/>

     <xs:element name="measurements">
       <xs:complexType>
         <xs:complexContent>
           <xs:restriction base="xs:anyType">
             <xs:sequence>
           <xs:any namespace="##other" processContents="lax"
                   minOccurs="0" maxOccurs="unbounded"/>
             </xs:sequence>
             <xs:attribute name="time" type="xs:dateTime"/>
             <xs:attribute name="timeError" type="bt:positiveDouble"/>
             <xs:attribute name="expires" type="xs:dateTime"/>
             <xs:anyAttribute namespace="##any" processContents="lax"/>
           </xs:restriction>
         </xs:complexContent>
       </xs:complexType>
     </xs:element>

     <xs:element name="measurementRequest"
             type="lm:measurementRequestType"/>
     <xs:complexType name="measurementRequestType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:sequence>
             <xs:element ref="lm:measurement"
                         minOccurs="0" maxOccurs="unbounded"/>



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             <xs:any namespace="##other" processContents="lax"
                     minOccurs="0" maxOccurs="unbounded"/>
           </xs:sequence>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>

     <xs:element name="measurement" type="lm:measurementType"/>
     <xs:complexType name="measurementType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:sequence>
             <xs:any namespace="##other" processContents="lax"
                     minOccurs="0" maxOccurs="unbounded"/>
           </xs:sequence>
           <xs:attribute name="type" type="xs:QName" use="required"/>
           <xs:attribute name="samples" type="xs:positiveInteger"/>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>

     <!-- PIDF-LO extension for source -->
     <xs:element name="source" type="lm:sourceType"/>
     <xs:simpleType name="sourceType">
       <xs:list>
         <xs:simpleType>
           <xs:restriction base="xs:token">
             <xs:enumeration value="lis"/>
             <xs:enumeration value="device"/>
             <xs:enumeration value="other"/>
           </xs:restriction>
         </xs:simpleType>
       </xs:list>
     </xs:simpleType>
   </xs:schema>

                       Measurement Container Schema














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8.2.  Measurement Source Schema

   <?xml version="1.0"?>
   <xs:schema
       xmlns:lmsrc="urn:ietf:params:xml:ns:pidf:geopriv10:lmsrc"
       xmlns:xs="http://www.w3.org/2001/XMLSchema"
       targetNamespace="urn:ietf:params:xml:ns:pidf:geopriv10:lmsrc"
       elementFormDefault="qualified"
       attributeFormDefault="unqualified">

     <xs:annotation>
       <xs:appinfo
           source="urn:ietf:params:xml:schema:pidf:geopriv10:lmsrc">
       </xs:appinfo>
       <xs:documentation
           source="http://www.rfc-editor.org/rfc/rfc7105.txt">
           This schema defines an extension to PIDF-LO that indicates
           the type of measurement source that produced the measurement
           data used in generating the associated location information.
       </xs:documentation>
     </xs:annotation>

     <xs:element name="source" type="lmsrc:sourceType"/>
     <xs:simpleType name="sourceType">
       <xs:list>
         <xs:simpleType>
           <xs:restriction base="xs:token">
             <xs:enumeration value="lis"/>
             <xs:enumeration value="device"/>
             <xs:enumeration value="other"/>
           </xs:restriction>
         </xs:simpleType>
       </xs:list>
     </xs:simpleType>
   </xs:schema>

                Measurement Source PIDF-LO Extension Schema














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8.3.  Base Types Schema

   Note that the pattern rules in the following schema wrap due to
   length constraints.  None of the patterns contain whitespace.

   <?xml version="1.0"?>
   <xs:schema
     xmlns:bt="urn:ietf:params:xml:ns:geopriv:lm:basetypes"
     xmlns:xs="http://www.w3.org/2001/XMLSchema"
     targetNamespace="urn:ietf:params:xml:ns:geopriv:lm:basetypes"
     elementFormDefault="qualified"
     attributeFormDefault="unqualified">

     <xs:annotation>
       <xs:appinfo
           source="urn:ietf:params:xml:schema:geopriv:lm:basetypes">
       </xs:appinfo>
       <xs:documentation
           source="http://www.rfc-editor.org/rfc/rfc7105.txt">
           This schema defines a set of base type elements.
       </xs:documentation>
     </xs:annotation>

     <xs:simpleType name="byteType">
       <xs:restriction base="xs:integer">
         <xs:minInclusive value="0"/>
         <xs:maxInclusive value="255"/>
       </xs:restriction>
     </xs:simpleType>
     <xs:simpleType name="twoByteType">
       <xs:restriction base="xs:integer">
         <xs:minInclusive value="0"/>
         <xs:maxInclusive value="65535"/>
       </xs:restriction>
     </xs:simpleType>

     <xs:simpleType name="nonNegativeDouble">
       <xs:restriction base="xs:double">
         <xs:minInclusive value="0.0"/>
       </xs:restriction>
     </xs:simpleType>
     <xs:simpleType name="positiveDouble">
       <xs:restriction base="bt:nonNegativeDouble">
         <xs:minExclusive value="0.0"/>
       </xs:restriction>
     </xs:simpleType>





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     <xs:complexType name="doubleWithRMSError">
       <xs:simpleContent>
         <xs:extension base="xs:double">
           <xs:attribute name="rmsError" type="bt:positiveDouble"/>
           <xs:attribute name="samples" type="xs:positiveInteger"/>
         </xs:extension>
       </xs:simpleContent>
     </xs:complexType>
     <xs:complexType name="nnDoubleWithRMSError">
       <xs:simpleContent>
         <xs:restriction base="bt:doubleWithRMSError">
           <xs:minInclusive value="0"/>
         </xs:restriction>
       </xs:simpleContent>
     </xs:complexType>

     <xs:simpleType name="ipAddressType">
       <xs:union memberTypes="bt:IPv6AddressType bt:IPv4AddressType"/>
     </xs:simpleType>

     <!-- IPv6 format definition -->
     <xs:simpleType name="IPv6AddressType">
       <xs:annotation>
         <xs:documentation>
             An IP version 6 address, based on RFC 4291.
         </xs:documentation>
       </xs:annotation>
       <xs:restriction base="xs:token">
         <!-- Fully specified address -->
         <xs:pattern value="[0-9A-Fa-f]{1,4}(:[0-9A-Fa-f]{1,4}){7}"/>
         <!-- Double colon start -->
         <xs:pattern value=":(:[0-9A-Fa-f]{1,4}){1,7}"/>
         <!-- Double colon middle -->
         <xs:pattern value="([0-9A-Fa-f]{1,4}:){1,6}
                            (:[0-9A-Fa-f]{1,4}){1}"/>
         <xs:pattern value="([0-9A-Fa-f]{1,4}:){1,5}
                            (:[0-9A-Fa-f]{1,4}){1,2}"/>
         <xs:pattern value="([0-9A-Fa-f]{1,4}:){1,4}
                            (:[0-9A-Fa-f]{1,4}){1,3}"/>
         <xs:pattern value="([0-9A-Fa-f]{1,4}:){1,3}
                            (:[0-9A-Fa-f]{1,4}){1,4}"/>
         <xs:pattern value="([0-9A-Fa-f]{1,4}:){1,2}
                            (:[0-9A-Fa-f]{1,4}){1,5}"/>
         <xs:pattern value="([0-9A-Fa-f]{1,4}:){1}
                            (:[0-9A-Fa-f]{1,4}){1,6}"/>
         <!-- Double colon end -->
         <xs:pattern value="([0-9A-Fa-f]{1,4}:){1,7}:"/>




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         <!-- IPv4-Compatible and IPv4-Mapped Addresses -->
         <xs:pattern value="((:(:0{1,4}){0,3}:[fF]{4})|(0{1,4}:
             (:0{1,4}){0,2}:[fF]{4})|((0{1,4}:){2}
             (:0{1,4})?:[fF]{4})|((0{1,4}:){3}:[fF]{4})
             |((0{1,4}:){4}[fF]{4})):(25[0-5]|2[0-4][0-9]|
             [0-1]?[0-9]?[0-9])\.(25[0-5]|2[0-4][0-9]|[0-1]
             ?[0-9]?[0-9])\.(25[0-5]|2[0-4][0-9]|[0-1]?
             [0-9]?[0-9])\.(25[0-5]|2[0-4][0-9]|[0-1]?
             [0-9]?[0-9])"/>
         <!-- The unspecified address -->
         <xs:pattern value="::"/>
       </xs:restriction>
     </xs:simpleType>

     <!-- IPv4 format definition -->
     <xs:simpleType name="IPv4AddressType">
       <xs:restriction base="xs:token">
         <xs:pattern value="(25[0-5]|2[0-4][0-9]|[0-1]?[0-9]?[0-9])\.
                            (25[0-5]|2[0-4][0-9]|[0-1]?[0-9]?[0-9])\.
                            (25[0-5]|2[0-4][0-9]|[0-1]?[0-9]?[0-9])\.
                            (25[0-5]|2[0-4][0-9]|[0-1]?[0-9]?[0-9])"/>
       </xs:restriction>
     </xs:simpleType>

     <!-- MAC address (EUI-48) or EUI-64 address -->
     <xs:simpleType name="macAddressType">
       <xs:restriction base="xs:token">
         <xs:pattern
     value="[\da-fA-F]{2}(-[\da-fA-F]{2}){5}((-[\da-fA-F]{2}){2})?"/>
       </xs:restriction>
     </xs:simpleType>
   </xs:schema>

                             Base Types Schema

















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8.4.  LLDP Measurement Schema

   <?xml version="1.0"?>
   <xs:schema
       xmlns:lldp="urn:ietf:params:xml:ns:geopriv:lm:lldp"
       xmlns:bt="urn:ietf:params:xml:ns:geopriv:lm:basetypes"
       xmlns:xs="http://www.w3.org/2001/XMLSchema"
       targetNamespace="urn:ietf:params:xml:ns:geopriv:lm:lldp"
       elementFormDefault="qualified"
       attributeFormDefault="unqualified">

     <xs:annotation>
       <xs:appinfo
           source="urn:ietf:params:xml:schema:geopriv:lm:lldp">
       </xs:appinfo>
       <xs:documentation
           source="http://www.rfc-editor.org/rfc/rfc7105.txt">
           This schema defines a set of LLDP location measurements.
       </xs:documentation>
     </xs:annotation>

    <xs:import namespace="urn:ietf:params:xml:ns:geopriv:lm:basetypes"/>

     <xs:element name="lldp" type="lldp:lldpMeasurementType"/>
     <xs:complexType name="lldpMeasurementType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:sequence>
             <xs:element name="chassis" type="lldp:lldpDataType"/>
             <xs:element name="port" type="lldp:lldpDataType"/>
             <xs:any namespace="##other" processContents="lax"
                     minOccurs="0" maxOccurs="unbounded"/>
           </xs:sequence>
           <xs:anyAttribute namespace="##any" processContents="lax"/>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>

     <xs:complexType name="lldpDataType">
       <xs:simpleContent>
         <xs:extension base="lldp:lldpOctetStringType">
           <xs:attribute name="type" type="bt:byteType"
                         use="required"/>
         </xs:extension>
       </xs:simpleContent>
     </xs:complexType>





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     <xs:simpleType name="lldpOctetStringType">
       <xs:restriction base="xs:hexBinary">
         <xs:minLength value="1"/>
         <xs:maxLength value="255"/>
       </xs:restriction>
     </xs:simpleType>
   </xs:schema>

                          LLDP Measurement Schema

8.5.  DHCP Measurement Schema

   <?xml version="1.0"?>
   <xs:schema
       xmlns:dhcp="urn:ietf:params:xml:ns:geopriv:lm:dhcp"
       xmlns:xs="http://www.w3.org/2001/XMLSchema"
       xmlns:bt="urn:ietf:params:xml:ns:geopriv:lm:basetypes"
       targetNamespace="urn:ietf:params:xml:ns:geopriv:lm:dhcp"
       elementFormDefault="qualified"
       attributeFormDefault="unqualified">

     <xs:annotation>
       <xs:appinfo
           source="urn:ietf:params:xml:schema:geopriv:lm:dhcp">
       </xs:appinfo>
       <xs:documentation
           source="http://www.rfc-editor.org/rfc/rfc7105.txt">
           This schema defines a set of DHCP location measurements.
       </xs:documentation>
     </xs:annotation>

    <xs:import namespace="urn:ietf:params:xml:ns:geopriv:lm:basetypes"/>

     <!-- DHCP Relay Agent Information option -->
     <xs:element name="dhcp-rai" type="dhcp:dhcpType"/>
     <xs:complexType name="dhcpType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:sequence>
             <xs:element name="giaddr" type="bt:ipAddressType"/>
             <xs:element name="circuit"
                         type="xs:hexBinary" minOccurs="0"/>
             <xs:element name="remote"
                         type="dhcp:dhcpRemoteType" minOccurs="0"/>
             <xs:element name="subscriber"
                         type="xs:hexBinary" minOccurs="0"/>





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             <xs:any namespace="##other" processContents="lax"
                     minOccurs="0" maxOccurs="unbounded"/>
           </xs:sequence>
           <xs:anyAttribute namespace="##any" processContents="lax"/>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>

     <xs:complexType name="dhcpRemoteType">
       <xs:simpleContent>
         <xs:extension base="xs:hexBinary">
           <xs:attribute name="enterprise" type="xs:positiveInteger"
                         use="optional"/>
         </xs:extension>
       </xs:simpleContent>
     </xs:complexType>
   </xs:schema>

                          DHCP Measurement Schema

8.6.  WiFi Measurement Schema

   <?xml version="1.0"?>
   <xs:schema
       xmlns:wifi="urn:ietf:params:xml:ns:geopriv:lm:wifi"
       xmlns:bt="urn:ietf:params:xml:ns:geopriv:lm:basetypes"
       xmlns:gml="http://www.opengis.net/gml"
       xmlns:xs="http://www.w3.org/2001/XMLSchema"
       targetNamespace="urn:ietf:params:xml:ns:geopriv:lm:wifi"
       elementFormDefault="qualified"
       attributeFormDefault="unqualified">

     <xs:annotation>
       <xs:appinfo
           source="urn:ietf:params:xml:schema:geopriv:lm:wifi">
         802.11 location measurements
       </xs:appinfo>
       <xs:documentation
           source="http://www.rfc-editor.org/rfc/rfc7105.txt">
           This schema defines a basic set of 802.11 location
           measurements.
       </xs:documentation>
     </xs:annotation>








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    <xs:import namespace="urn:ietf:params:xml:ns:geopriv:lm:basetypes"/>
     <xs:import namespace="http://www.opengis.net/gml"/>

     <xs:element name="wifi" type="wifi:wifiNetworkType"/>

     <xs:complexType name="wifiNetworkType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:sequence>
             <xs:element name="nicType" type="xs:token"
                         minOccurs="0"/>
             <xs:element name="ap" type="wifi:wifiType"
                         maxOccurs="unbounded"/>
           </xs:sequence>
           <xs:anyAttribute namespace="##any" processContents="lax"/>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>

     <xs:complexType name="wifiType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:sequence>
             <xs:element name="bssid" type="wifi:bssidType"/>
             <xs:element name="ssid" type="wifi:ssidType"
                         minOccurs="0"/>
             <xs:element name="channel" type="xs:nonNegativeInteger"
                         minOccurs="0"/>
             <xs:element name="location" minOccurs="0"
                         type="xs:anyType"/>
             <xs:element name="type" type="wifi:networkType"
                         minOccurs="0"/>
             <xs:element name="regclass" type="wifi:regclassType"
                         minOccurs="0"/>
             <xs:element name="antenna" type="wifi:octetType"
                         minOccurs="0"/>
             <xs:element name="flightTime" minOccurs="0"
                         type="bt:nnDoubleWithRMSError"/>
             <xs:element name="apSignal" type="wifi:signalType"
                         minOccurs="0"/>
             <xs:element name="deviceSignal" type="wifi:signalType"
                         minOccurs="0"/>
             <xs:any namespace="##other" processContents="lax"
                     minOccurs="0" maxOccurs="unbounded"/>
           </xs:sequence>
           <xs:attribute name="serving" type="xs:boolean"
                         default="false"/>
           <xs:anyAttribute namespace="##any" processContents="lax"/>



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         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>

     <xs:complexType name="bssidType">
       <xs:simpleContent>
         <xs:extension base="bt:macAddressType">
           <xs:attribute name="verified" type="xs:boolean"
                         default="false"/>
         </xs:extension>
       </xs:simpleContent>
     </xs:complexType>

     <!-- Note that this pattern does not prevent multibyte UTF-8
          sequences that result in an SSID longer than 32 octets. -->
     <xs:simpleType name="ssidType">
       <xs:restriction base="xs:token">
         <xs:pattern value="(\\[\da-fA-F]{2}|[^\\]){0,32}"/>
       </xs:restriction>
     </xs:simpleType>

     <xs:simpleType name="networkType">
       <xs:restriction base="xs:token">
         <xs:pattern value="[a-zA-Z]+"/>
       </xs:restriction>
     </xs:simpleType>

     <xs:complexType name="regclassType">
       <xs:simpleContent>
         <xs:extension base="wifi:octetType">
           <xs:attribute name="country">
             <xs:simpleType>
               <xs:restriction base="xs:token">
                 <xs:pattern value="[A-Z]{2}[OIX]?"/>
               </xs:restriction>
             </xs:simpleType>
           </xs:attribute>
         </xs:extension>
       </xs:simpleContent>
     </xs:complexType>

     <xs:simpleType name="octetType">
       <xs:restriction base="xs:nonNegativeInteger">
         <xs:maxInclusive value="255"/>
       </xs:restriction>
     </xs:simpleType>





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     <xs:complexType name="signalType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:sequence>
             <xs:element name="transmit" type="xs:double"
                         minOccurs="0"/>
             <xs:element name="gain" type="xs:double" minOccurs="0"/>
             <xs:element name="rcpi" type="wifi:rssiType"
                         minOccurs="0"/>
             <xs:element name="rsni" type="bt:doubleWithRMSError"
                         minOccurs="0"/>
             <xs:any namespace="##other" processContents="lax"
                     minOccurs="0" maxOccurs="unbounded"/>
           </xs:sequence>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>

     <xs:complexType name="rssiType">
       <xs:simpleContent>
         <xs:extension base="bt:doubleWithRMSError">
           <xs:attribute name="dBm" type="xs:boolean" default="true"/>
         </xs:extension>
       </xs:simpleContent>
     </xs:complexType>

     <!-- Measurement Request elements -->
     <xs:element name="type" type="wifi:networkType"/>
     <xs:element name="parameter" type="wifi:parameterType"/>

     <xs:complexType name="parameterType">
       <xs:simpleContent>
         <xs:extension base="xs:QName">
           <xs:attribute name="context" use="optional">
             <xs:simpleType>
               <xs:restriction base="xs:token">
                 <xs:enumeration value="ap"/>
                 <xs:enumeration value="device"/>
               </xs:restriction>
             </xs:simpleType>
           </xs:attribute>
         </xs:extension>
       </xs:simpleContent>
     </xs:complexType>
   </xs:schema>

                          WiFi Measurement Schema




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8.7.  Cellular Measurement Schema

   <?xml version="1.0"?>
   <xs:schema
       xmlns:cell="urn:ietf:params:xml:ns:geopriv:lm:cell"
       xmlns:xs="http://www.w3.org/2001/XMLSchema"
       targetNamespace="urn:ietf:params:xml:ns:geopriv:lm:cell"
       elementFormDefault="qualified"
       attributeFormDefault="unqualified">

     <xs:annotation>
       <xs:appinfo
           source="urn:ietf:params:xml:schema:geopriv:lm:cell">
       </xs:appinfo>
       <xs:documentation
           source="http://www.rfc-editor.org/rfc/rfc7105.txt">
           This schema defines a set of cellular location measurements.
       </xs:documentation>
     </xs:annotation>

     <xs:element name="cellular" type="cell:cellularType"/>

     <xs:complexType name="cellularType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:sequence>
             <xs:choice>
               <xs:element name="servingCell" type="cell:cellType"/>
               <xs:element name="observedCell" type="cell:cellType"/>
             </xs:choice>
             <xs:element name="observedCell" type="cell:cellType"
                         minOccurs="0" maxOccurs="unbounded"/>
           </xs:sequence>
           <xs:anyAttribute namespace="##any" processContents="lax"/>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>

     <xs:complexType name="cellType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:choice>
             <xs:sequence>
               <xs:element name="mcc" type="cell:mccType"/>
               <xs:element name="mnc" type="cell:mncType"/>
               <xs:choice>
                 <xs:sequence>
                   <xs:choice>



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                     <xs:element name="rnc" type="cell:cellIdType"/>
                     <xs:element name="lac" type="cell:cellIdType"/>
                   </xs:choice>
                   <xs:element name="cid" type="cell:cellIdType"/>
                 </xs:sequence>
                 <xs:element name="eucid" type="cell:cellIdType"/>
               </xs:choice>
               <xs:any namespace="##other" processContents="lax"
                       minOccurs="0" maxOccurs="unbounded"/>
             </xs:sequence>
             <xs:sequence>
               <xs:element name="sid" type="cell:cellIdType"/>
               <xs:element name="nid" type="cell:cellIdType"/>
               <xs:element name="baseid" type="cell:cellIdType"/>
               <xs:any namespace="##other" processContents="lax"
                       minOccurs="0" maxOccurs="unbounded"/>
             </xs:sequence>
             <xs:any namespace="##other" processContents="lax"
                     minOccurs="0" maxOccurs="unbounded"/>
           </xs:choice>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>

     <xs:simpleType name="mccType">
       <xs:restriction base="xs:token">
         <xs:pattern value="[0-9]{3}"/>
       </xs:restriction>
     </xs:simpleType>

     <xs:simpleType name="mncType">
       <xs:restriction base="xs:token">
         <xs:pattern value="[0-9]{2,3}"/>
       </xs:restriction>
     </xs:simpleType>

     <xs:simpleType name="cellIdType">
       <xs:restriction base="xs:nonNegativeInteger">
         <xs:maxInclusive value="268435455"/> <!-- 2^28 (eucid) -->
       </xs:restriction>
     </xs:simpleType>

     <!-- Measurement Request elements -->
     <xs:element name="type" type="cell:typeType"/>
     <xs:simpleType name="typeType">
       <xs:restriction base="xs:token">
         <xs:enumeration value="gsm"/>
         <xs:enumeration value="umts"/>



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         <xs:enumeration value="lte"/>
         <xs:enumeration value="cdma"/>
       </xs:restriction>
     </xs:simpleType>

     <xs:element name="network" type="cell:networkType"/>
     <xs:complexType name="networkType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:choice>
             <xs:sequence>
               <xs:element name="mcc" type="cell:mccType"/>
               <xs:element name="mnc" type="cell:mncType"/>
             </xs:sequence>
             <xs:element name="nid" type="cell:cellIdType"/>
           </xs:choice>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>
   </xs:schema>

                        Cellular Measurement Schema

8.8.  GNSS Measurement Schema

   <?xml version="1.0"?>
   <xs:schema
       xmlns:gnss="urn:ietf:params:xml:ns:geopriv:lm:gnss"
       xmlns:bt="urn:ietf:params:xml:ns:geopriv:lm:basetypes"
       xmlns:xs="http://www.w3.org/2001/XMLSchema"
       targetNamespace="urn:ietf:params:xml:ns:geopriv:lm:gnss"
       elementFormDefault="qualified"
       attributeFormDefault="unqualified">

     <xs:annotation>
       <xs:appinfo
           source="urn:ietf:params:xml:schema:geopriv:lm:gnss">
       </xs:appinfo>
       <xs:documentation
           source="http://www.rfc-editor.org/rfc/rfc7105.txt">
           This schema defines a set of GNSS location measurements.
       </xs:documentation>
     </xs:annotation>








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    <xs:import namespace="urn:ietf:params:xml:ns:geopriv:lm:basetypes"/>

     <!-- GNSS -->
     <xs:element name="gnss" type="gnss:gnssMeasurementType">
       <xs:unique name="gnssSatellite">
         <xs:selector xpath="sat"/>
         <xs:field xpath="@num"/>
       </xs:unique>
     </xs:element>

     <xs:complexType name="gnssMeasurementType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:sequence>
             <xs:element name="gnssTime" type="bt:nnDoubleWithRMSError"
                         minOccurs="0"/>
             <xs:element name="sat" type="gnss:gnssSatelliteType"
                         minOccurs="1" maxOccurs="64"/>
             <xs:any namespace="##other" processContents="lax"
                     minOccurs="0" maxOccurs="unbounded"/>
           </xs:sequence>
           <xs:attribute name="system" type="xs:token" use="required"/>
           <xs:attribute name="signal" type="xs:token"/>
           <xs:anyAttribute namespace="##any" processContents="lax"/>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>

     <xs:complexType name="gnssSatelliteType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:sequence>
             <xs:element name="doppler" type="bt:doubleWithRMSError"/>
             <xs:element name="codephase"
                         type="bt:nnDoubleWithRMSError"/>
             <xs:element name="cn0" type="bt:nonNegativeDouble"/>
             <xs:element name="mp" type="bt:positiveDouble"
                         minOccurs="0"/>
             <xs:element name="cq" type="gnss:codePhaseQualityType"
                         minOccurs="0"/>
             <xs:element name="adr" type="xs:double" minOccurs="0"/>
           </xs:sequence>
           <xs:attribute name="num" type="xs:positiveInteger"
                         use="required"/>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>




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     <xs:complexType name="codePhaseQualityType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:attribute name="continuous" type="xs:boolean"
                         default="true"/>
           <xs:attribute name="direct" use="required">
             <xs:simpleType>
               <xs:restriction base="xs:token">
                 <xs:enumeration value="direct"/>
                 <xs:enumeration value="inverted"/>
               </xs:restriction>
             </xs:simpleType>
           </xs:attribute>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>
   </xs:schema>

                          GNSS Measurement Schema

8.9.  DSL Measurement Schema

   <?xml version="1.0"?>
   <xs:schema
       xmlns:dsl="urn:ietf:params:xml:ns:geopriv:lm:dsl"
       xmlns:bt="urn:ietf:params:xml:ns:geopriv:lm:basetypes"
       xmlns:xs="http://www.w3.org/2001/XMLSchema"
       targetNamespace="urn:ietf:params:xml:ns:geopriv:lm:dsl"
       elementFormDefault="qualified"
       attributeFormDefault="unqualified">

     <xs:annotation>
       <xs:appinfo
           source="urn:ietf:params:xml:schema:geopriv:lm:dsl">
         DSL measurement definitions
       </xs:appinfo>
       <xs:documentation
           source="http://www.rfc-editor.org/rfc/rfc7105.txt">
           This schema defines a basic set of DSL location measurements.
       </xs:documentation>
     </xs:annotation>










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    <xs:import namespace="urn:ietf:params:xml:ns:geopriv:lm:basetypes"/>

     <xs:element name="dsl" type="dsl:dslVlanType"/>
     <xs:complexType name="dslVlanType">
       <xs:complexContent>
         <xs:restriction base="xs:anyType">
           <xs:choice>
             <xs:element name="l2tp">
               <xs:complexType>
                 <xs:complexContent>
                   <xs:restriction base="xs:anyType">
                     <xs:sequence>
                       <xs:element name="src" type="bt:ipAddressType"/>
                       <xs:element name="dest" type="bt:ipAddressType"/>
                       <xs:element name="session"
                                   type="xs:nonNegativeInteger"/>
                     </xs:sequence>
                   </xs:restriction>
                 </xs:complexContent>
               </xs:complexType>
             </xs:element>
             <xs:sequence>
               <xs:element name="an" type="xs:token"/>
               <xs:group ref="dsl:dslSlotPort"/>
             </xs:sequence>
             <xs:sequence>
               <xs:element name="stag" type="dsl:vlanIDType"/>
               <xs:choice>
                 <xs:sequence>
                   <xs:element name="ctag" type="dsl:vlanIDType"/>
                   <xs:group ref="dsl:dslSlotPort" minOccurs="0"/>
                 </xs:sequence>
                 <xs:group ref="dsl:dslSlotPort"/>
               </xs:choice>
             </xs:sequence>
             <xs:sequence>
               <xs:element name="vpi" type="bt:byteType"/>
               <xs:element name="vci" type="bt:twoByteType"/>
             </xs:sequence>
             <xs:any namespace="##other" processContents="lax"
                     minOccurs="0" maxOccurs="unbounded"/>
           </xs:choice>
           <xs:anyAttribute namespace="##other" processContents="lax"/>
         </xs:restriction>
       </xs:complexContent>
     </xs:complexType>





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     <xs:simpleType name="vlanIDType">
       <xs:restriction base="xs:nonNegativeInteger">
         <xs:maxInclusive value="4095"/>
       </xs:restriction>
     </xs:simpleType>
     <xs:group name="dslSlotPort">
       <xs:sequence>
         <xs:element name="slot" type="xs:token"/>
         <xs:element name="port" type="xs:token"/>
       </xs:sequence>
     </xs:group>
   </xs:schema>

                          DSL Measurement Schema

9.  IANA Considerations

   This section creates a registry for GNSS types (Section 5.5) and
   registers the namespaces and schemas defined in Section 8.

9.1.  IANA Registry for GNSS Types

   This document establishes a new IANA registry for "Global Navigation
   Satellite System (GNSS)" types.  The registry includes tokens for the
   GNSS type and for each of the signals within that type.  Referring to
   [RFC5226], this registry operates under "Specification Required"
   rules.  The IESG will appoint an Expert Reviewer who will advise IANA
   promptly on each request for a new or updated GNSS type.

   Each entry in the registry requires the following information:

   GNSS Name:  the name of the GNSS

   Brief Description:  a brief description of the GNSS

   GNSS Token:  a token that can be used to identify the GNSS

   Signals:  a set of tokens that represent each of the signals that the
      system provides

   Documentation Reference:  a reference to one or more stable, public
      specifications that outline usage of the GNSS, including (but not
      limited to) signal specifications and time systems

   The registry initially includes two registrations:

   GNSS Name:  Global Positioning System (GPS)




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   Brief Description:  a system of satellites that use spread-spectrum
      transmission, operated by the US military for commercial and
      military applications

   GNSS Token:  gps

   Signals:  L1, L2, L1C, L2C, L5

   Documentation Reference:  Navstar GPS Space Segment/Navigation User
      Interface [GPS.ICD]

   GNSS Name:  Galileo

   Brief Description:  a system of satellites that operate in the same
      spectrum as GPS, operated by the European Union for commercial
      applications

   GNSS Token:  galileo

   Signals:  L1, E5A, E5B, E5A+B, E6

   Documentation Reference:  Galileo Open Service Signal In Space
      Interface Control Document (SIS ICD) [Galileo.ICD]

9.2.  URN Sub-Namespace Registration for
      urn:ietf:params:xml:ns:pidf:geopriv10:lmsrc

   This section registers a new XML namespace,
   "urn:ietf:params:xml:ns:pidf:geopriv10:lmsrc", as per the guidelines
   in [RFC3688].

      URI: urn:ietf:params:xml:ns:pidf:geopriv10:lmsrc

      Registrant Contact: IETF, GEOPRIV working group
      (geopriv@ietf.org), Martin Thomson (martin.thomson@gmail.com).

      XML:

         BEGIN
       <?xml version="1.0"?>
       <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
       <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
         <head>
           <title>Measurement Source for PIDF-LO</title>
         </head>





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         <body>
           <h1>Namespace for Location Measurement Source</h1>
           <h2>urn:ietf:params:xml:ns:pidf:geopriv10:lmsrc</h2>
           <p>See <a href="http://www.rfc-editor.org/rfc/rfc7105.txt">
              RFC 7105</a>.</p>
         </body>
       </html>
         END

9.3.  URN Sub-Namespace Registration for
      urn:ietf:params:xml:ns:geopriv:lm

   This section registers a new XML namespace,
   "urn:ietf:params:xml:ns:geopriv:lm", as per the guidelines in
   [RFC3688].

      URI: urn:ietf:params:xml:ns:geopriv:lm

      Registrant Contact: IETF, GEOPRIV working group
      (geopriv@ietf.org), Martin Thomson (martin.thomson@gmail.com).

      XML:

         BEGIN
       <?xml version="1.0"?>
       <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
       <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
         <head>
           <title>Measurement Container</title>
         </head>
         <body>
           <h1>Namespace for Location Measurement Container</h1>
           <h2>urn:ietf:params:xml:ns:geopriv:lm</h2>
           <p>See <a href="http://www.rfc-editor.org/rfc/rfc7105.txt">
              RFC 7105</a>.</p>
         </body>
       </html>
         END

9.4.  URN Sub-Namespace Registration for
      urn:ietf:params:xml:ns:geopriv:lm:basetypes

   This section registers a new XML namespace,
   "urn:ietf:params:xml:ns:geopriv:lm:basetypes", as per the guidelines
   in [RFC3688].

      URI: urn:ietf:params:xml:ns:geopriv:lm:basetypes



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      Registrant Contact: IETF, GEOPRIV working group
      (geopriv@ietf.org), Martin Thomson (martin.thomson@gmail.com).

      XML:

         BEGIN
       <?xml version="1.0"?>
       <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
       <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
         <head>
           <title>Base Device Types</title>
         </head>
         <body>
           <h1>Namespace for Base Types</h1>
           <h2>urn:ietf:params:xml:ns:geopriv:lm:basetypes</h2>
           <p>See <a href="http://www.rfc-editor.org/rfc/rfc7105.txt">
              RFC 7105</a>.</p>
         </body>
       </html>
         END

9.5.  URN Sub-Namespace Registration for
      urn:ietf:params:xml:ns:geopriv:lm:lldp

   This section registers a new XML namespace,
   "urn:ietf:params:xml:ns:geopriv:lm:lldp", as per the guidelines in
   [RFC3688].

      URI: urn:ietf:params:xml:ns:geopriv:lm:lldp

      Registrant Contact: IETF, GEOPRIV working group
      (geopriv@ietf.org), Martin Thomson (martin.thomson@gmail.com).

      XML:

         BEGIN
       <?xml version="1.0"?>
       <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
       <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
         <head>
           <title>LLDP Measurement Set</title>
         </head>







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         <body>
           <h1>Namespace for LLDP Measurement Set</h1>
           <h2>urn:ietf:params:xml:ns:geopriv:lm:lldp</h2>
           <p>See <a href="http://www.rfc-editor.org/rfc/rfc7105.txt">
              RFC 7105</a>.</p>
         </body>
       </html>
         END

9.6.  URN Sub-Namespace Registration for
      urn:ietf:params:xml:ns:geopriv:lm:dhcp

   This section registers a new XML namespace,
   "urn:ietf:params:xml:ns:geopriv:lm:dhcp", as per the guidelines in
   [RFC3688].

      URI: urn:ietf:params:xml:ns:geopriv:lm:dhcp

      Registrant Contact: IETF, GEOPRIV working group
      (geopriv@ietf.org), Martin Thomson (martin.thomson@gmail.com).

      XML:

         BEGIN
       <?xml version="1.0"?>
       <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
       <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
         <head>
           <title>DHCP Measurement Set</title>
         </head>
         <body>
           <h1>Namespace for DHCP Measurement Set</h1>
           <h2>urn:ietf:params:xml:ns:geopriv:lm:dhcp</h2>
           <p>See <a href="http://www.rfc-editor.org/rfc/rfc7105.txt">
              RFC 7105</a>.</p>
         </body>
       </html>
         END

9.7.  URN Sub-Namespace Registration for
      urn:ietf:params:xml:ns:geopriv:lm:wifi

   This section registers a new XML namespace,
   "urn:ietf:params:xml:ns:geopriv:lm:wifi", as per the guidelines in
   [RFC3688].

      URI: urn:ietf:params:xml:ns:geopriv:lm:wifi



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      Registrant Contact: IETF, GEOPRIV working group
      (geopriv@ietf.org), Martin Thomson (martin.thomson@gmail.com).

      XML:

         BEGIN
       <?xml version="1.0"?>
       <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
       <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
         <head>
           <title>WiFi Measurement Set</title>
         </head>
         <body>
           <h1>Namespace for WiFi Measurement Set</h1>
           <h2>urn:ietf:params:xml:ns:geopriv:lm:wifi</h2>
           <p>See <a href="http://www.rfc-editor.org/rfc/rfc7105.txt">
              RFC 7105</a>.</p>
         </body>
       </html>
         END

9.8.  URN Sub-Namespace Registration for
      urn:ietf:params:xml:ns:geopriv:lm:cell

   This section registers a new XML namespace,
   "urn:ietf:params:xml:ns:geopriv:lm:cell", as per the guidelines in
   [RFC3688].

      URI: urn:ietf:params:xml:ns:geopriv:lm:cell

      Registrant Contact: IETF, GEOPRIV working group
      (geopriv@ietf.org), Martin Thomson (martin.thomson@gmail.com).

      XML:

         BEGIN
       <?xml version="1.0"?>
       <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
       <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
         <head>
           <title>Cellular Measurement Set</title>
         </head>







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         <body>
           <h1>Namespace for Cellular Measurement Set</h1>
           <h2>urn:ietf:params:xml:ns:geopriv:lm:cell</h2>
           <p>See <a href="http://www.rfc-editor.org/rfc/rfc7105.txt">
              RFC 7105</a>.</p>
         </body>
       </html>
         END

9.9.  URN Sub-Namespace Registration for
      urn:ietf:params:xml:ns:geopriv:lm:gnss

   This section registers a new XML namespace,
   "urn:ietf:params:xml:ns:geopriv:lm:gnss", as per the guidelines in
   [RFC3688].

      URI: urn:ietf:params:xml:ns:geopriv:lm:gnss

      Registrant Contact: IETF, GEOPRIV working group
      (geopriv@ietf.org), Martin Thomson (martin.thomson@gmail.com).

      XML:

         BEGIN
       <?xml version="1.0"?>
       <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
       <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
         <head>
           <title>GNSS Measurement Set</title>
         </head>
         <body>
           <h1>Namespace for GNSS Measurement Set</h1>
           <h2>urn:ietf:params:xml:ns:geopriv:lm:gnss</h2>
           <p>See <a href="http://www.rfc-editor.org/rfc/rfc7105.txt">
              RFC 7105</a>.</p>
         </body>
       </html>
         END

9.10.  URN Sub-Namespace Registration for
       urn:ietf:params:xml:ns:geopriv:lm:dsl

   This section registers a new XML namespace,
   "urn:ietf:params:xml:ns:geopriv:lm:dsl", as per the guidelines in
   [RFC3688].

      URI: urn:ietf:params:xml:ns:geopriv:lm:dsl



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      Registrant Contact: IETF, GEOPRIV working group
      (geopriv@ietf.org), Martin Thomson (martin.thomson@gmail.com).

      XML:

         BEGIN
       <?xml version="1.0"?>
       <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
       <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
         <head>
           <title>DSL Measurement Set</title>
         </head>
         <body>
           <h1>Namespace for DSL Measurement Set</h1>
           <h2>urn:ietf:params:xml:ns:geopriv:lm:dsl</h2>
           <p>See <a href="http://www.rfc-editor.org/rfc/rfc7105.txt">
              RFC 7105</a>.</p>
         </body>
       </html>
         END

9.11.  XML Schema Registration for Measurement Source Schema

   This section registers an XML schema as per the guidelines in
   [RFC3688].

   URI:  urn:ietf:params:xml:schema:pidf:geopriv10:lmsrc

   Registrant Contact:  IETF, GEOPRIV working group (geopriv@ietf.org),
      Martin Thomson (martin.thomson@gmail.com).

   Schema:  The XML for this schema can be found in Section 8.2 of this
      document.

9.12.  XML Schema Registration for Measurement Container Schema

   This section registers an XML schema as per the guidelines in
   [RFC3688].

   URI:  urn:ietf:params:xml:schema:geopriv:lm

   Registrant Contact:  IETF, GEOPRIV working group (geopriv@ietf.org),
      Martin Thomson (martin.thomson@gmail.com).

   Schema:  The XML for this schema can be found in Section 8.1 of this
      document.




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9.13.  XML Schema Registration for Base Types Schema

   This section registers an XML schema as per the guidelines in
   [RFC3688].

   URI:  urn:ietf:params:xml:schema:geopriv:lm:basetypes

   Registrant Contact:  IETF, GEOPRIV working group (geopriv@ietf.org),
      Martin Thomson (martin.thomson@gmail.com).

   Schema:  The XML for this schema can be found in Section 8.3 of this
      document.

9.14.  XML Schema Registration for LLDP Schema

   This section registers an XML schema as per the guidelines in
   [RFC3688].

   URI:  urn:ietf:params:xml:schema:geopriv:lm:lldp

   Registrant Contact:  IETF, GEOPRIV working group (geopriv@ietf.org),
      Martin Thomson (martin.thomson@gmail.com).

   Schema:  The XML for this schema can be found in Section 8.4 of this
      document.

9.15.  XML Schema Registration for DHCP Schema

   This section registers an XML schema as per the guidelines in
   [RFC3688].

   URI:  urn:ietf:params:xml:schema:geopriv:lm:dhcp

   Registrant Contact:  IETF, GEOPRIV working group (geopriv@ietf.org),
      Martin Thomson (martin.thomson@gmail.com).

   Schema:  The XML for this schema can be found in Section 8.5 of this
      document.

9.16.  XML Schema Registration for WiFi Schema

   This section registers an XML schema as per the guidelines in
   [RFC3688].

   URI:  urn:ietf:params:xml:schema:geopriv:lm:wifi

   Registrant Contact:  IETF, GEOPRIV working group (geopriv@ietf.org),
      Martin Thomson (martin.thomson@gmail.com).



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   Schema:  The XML for this schema can be found in Section 8.6 of this
      document.

9.17.  XML Schema Registration for Cellular Schema

   This section registers an XML schema as per the guidelines in
   [RFC3688].

   URI:  urn:ietf:params:xml:schema:geopriv:lm:cell

   Registrant Contact:  IETF, GEOPRIV working group (geopriv@ietf.org),
      Martin Thomson (martin.thomson@gmail.com).

   Schema:  The XML for this schema can be found in Section 8.7 of this
      document.

9.18.  XML Schema Registration for GNSS Schema

   This section registers an XML schema as per the guidelines in
   [RFC3688].

   URI:  urn:ietf:params:xml:schema:geopriv:lm:gnss

   Registrant Contact:  IETF, GEOPRIV working group (geopriv@ietf.org),
      Martin Thomson (martin.thomson@gmail.com).

   Schema:  The XML for this schema can be found in Section 8.8 of this
      document.

9.19.  XML Schema Registration for DSL Schema

   This section registers an XML schema as per the guidelines in
   [RFC3688].

   URI:  urn:ietf:params:xml:schema:geopriv:lm:dsl

   Registrant Contact:  IETF, GEOPRIV working group (geopriv@ietf.org),
      Martin Thomson (martin.thomson@gmail.com).

   Schema:  The XML for this schema can be found in Section 8.9 of this
      document.

10.  Acknowledgements

   Thanks go to Simon Cox for his comments relating to terminology; his
   comments have helped ensure that this document is aligned with
   ongoing work in the Open Geospatial Consortium (OGC).  Thanks to Neil
   Harper for his review and comments on the GNSS sections of this



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   document.  Thanks to Noor-E-Gagan Singh, Gabor Bajko, Russell Priebe,
   and Khalid Al-Mufti for their significant input to, and suggestions
   for, improving the 802.11 measurements.  Thanks to Cullen Jennings
   for feedback and suggestions.  Bernard Aboba provided review and
   feedback on a range of measurement data definitions.  Mary Barnes and
   Geoff Thompson provided a review and corrections.  David Waitzman and
   John Bressler both noted shortcomings with 802.11 measurements.
   Keith Drage and Darren Pawson provided expert LTE knowledge.

11.  References

11.1.  Normative References

   [ASCII]    ANSI, "US-ASCII. Coded Character Set - 7-Bit American
              Standard Code for Information Interchange. Standard ANSI
              X3.4-1986", 1986.

   [GPS.ICD]  "Navstar GPS Space Segment/Navigation User Interface", ICD
              GPS-200, April 2000.

   [Galileo.ICD]
              GJU, "Galileo Open Service Signal In Space Interface
              Control Document (SIS ICD)", May 2006.

   [IANA.enterprise]
              IANA, "Private Enterprise Numbers", 2014,
              <http://www.iana.org/assignments/enterprise-numbers>.

   [IEEE.80211]
              IEEE, "Wireless LAN Medium Access Control (MAC) and
              Physical Layer (PHY) Specifications", IEEE
              Std 802.11-2012, March 2012.

   [IEEE.8021AB]
              IEEE, "IEEE Standard for Local and Metropolitan Area
              Networks, Station and Media Access Control Connectivity
              Discovery", IEEE Std 802.1AB-2009, September 2009.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3046]  Patrick, M., "DHCP Relay Agent Information Option",
              RFC 3046, January 2001.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.




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   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of
              ISO 10646", STD 63, RFC 3629, November 2003.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [RFC3993]  Johnson, R., Palaniappan, T., and M. Stapp, "Subscriber-ID
              Suboption for the Dynamic Host Configuration Protocol
              (DHCP) Relay Agent Option", RFC 3993, March 2005.

   [RFC4119]  Peterson, J., "A Presence-based GEOPRIV Location Object
              Format", RFC 4119, December 2005.

   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, February 2006.

   [RFC4580]  Volz, B., "Dynamic Host Configuration Protocol for IPv6
              (DHCPv6) Relay Agent Subscriber-ID Option", RFC 4580,
              June 2006.

   [RFC4649]  Volz, B., "Dynamic Host Configuration Protocol for IPv6
              (DHCPv6) Relay Agent Remote-ID Option", RFC 4649,
              August 2006.

   [RFC5491]  Winterbottom, J., Thomson, M., and H. Tschofenig, "GEOPRIV
              Presence Information Data Format Location Object (PIDF-LO)
              Usage Clarification, Considerations, and Recommendations",
              RFC 5491, March 2009.

   [RFC5952]  Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
              Address Text Representation", RFC 5952, August 2010.

   [RFC5985]  Barnes, M., "HTTP-Enabled Location Delivery (HELD)",
              RFC 5985, September 2010.

   [RFC5986]  Thomson, M. and J. Winterbottom, "Discovering the Local
              Location Information Server (LIS)", RFC 5986,
              September 2010.

   [TIA-2000.5]
              TIA/EIA, "Upper Layer (Layer 3) Signaling Standard for
              cdma2000(R) Spread Spectrum Systems", TR-45.5 / TSG-C
              TIA-2000.5-E / C.S0005-E v1.0, September 2009.







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   [TS.3GPP.23.003]
              3GPP, "Numbering, addressing and identification", 3GPP TS
              23.003 12.0.0, September 2013,
              <http://www.3gpp.org/ftp/Specs/html-info/23003.htm>.

11.2.  Informative References

   [ANSI-TIA-1057]
              ANSI/TIA, "Link Layer Discovery Protocol for Media
              Endpoint Devices", TIA 1057, April 2006.

   [DSL.TR025]
              Wang, R., "Core Network Architecture Recommendations for
              Access to Legacy Data Networks over ADSL", September 1999.

   [DSL.TR101]
              Cohen, A. and E. Shrum, "Migration to Ethernet-Based DSL
              Aggregation", April 2006.

   [GPS.SPOOF]
              Scott, L., "Anti-Spoofing and Authenticated Signal
              Architectures for Civil Navigation Signals", ION-GNSS
              Portland, Oregon, 2003.

   [HARPER]   Harper, N., "Server-side GPS and Assisted-GPS in Java",
              December 2009.

   [RFC2661]  Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn,
              G., and B. Palter, "Layer Two Tunneling Protocol "L2TP"",
              RFC 2661, August 1999.

   [RFC2865]  Rigney, C., Willens, S., Rubens, A., and W. Simpson,
              "Remote Authentication Dial In User Service (RADIUS)",
              RFC 2865, June 2000.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              January 2004.

   [RFC3693]  Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and
              J. Polk, "Geopriv Requirements", RFC 3693, February 2004.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC6155]  Winterbottom, J., Thomson, M., Tschofenig, H., and R.
              Barnes, "Use of Device Identity in HTTP-Enabled Location
              Delivery (HELD)", RFC 6155, March 2011.



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   [RFC6280]  Barnes, R., Lepinski, M., Cooper, A., Morris, J.,
              Tschofenig, H., and H. Schulzrinne, "An Architecture for
              Location and Location Privacy in Internet Applications",
              BCP 160, RFC 6280, July 2011.

Authors' Addresses

   Martin Thomson
   Mozilla
   Suite 300
   650 Castro Street
   Mountain View, CA  94041
   US

   EMail: martin.thomson@gmail.com


   James Winterbottom
   Unaffiliated
   AU

   EMail: a.james.winterbottom@gmail.com





























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