3GPP standards shall support location service features, to allow new and innovative location-based services to be developed. It shall be possible to identify and report in a standard format (e.g. geographical co-ordinates) the current location of the user's terminal and to make the information available to the user, ME, network operator, service provider, value added service providers and for PLMN internal operations. The location is provided to identify the likely location of specific MEs. This is meant to be used for charging, location-based services, lawful interception, emergency calls, etc., as well as the positioning services. The standard shall support NG-RAN, E-UTRAN, GERAN and UTRAN to facilitate determination of the location of a mobile station. The following subsections provide general descriptions of attributes that can be used to describe or characterize various location services. The relative importance of these attributes varies from service to service. However, accuracy, coverage, privacy and transaction rate may be considered the primary distinguishing attributes that define a value-added service. Briefly:

• accuracy is the difference between actual location and estimated location,
• coverage is an expression of the geographic area in which the UE user will receive an adequate perceived quality of service,
• privacy describes the user's perception of confidentiality of the location information, and
• transaction rate indicates how frequently network messaging is required to support the service.

A general comparison of the specific attributes of various location-based services is provided in Annex C of this document.

The following high-level requirements are applicable:

1. The supporting mechanisms should incorporate flexible modular components with open interfaces that facilitate equipment interoperability and the evolution of service providing capabilities.
2. The network should be sufficiently flexible to accommodate evolving enabling mechanisms and service requirements to provide new and improved services.
3. It shall be possible to provide multiple layers of permissions to comply with local, national, and regional privacy requirements.
4. Multiple positioning methods should be supported in the different Access Networks, including (but not limited to):
   • Modernized GPS;
   • SBAS (Satellite Based Augmentation Systems: EGNOS, WAAS, GAGAN, MSAS);
   • QZSS (Quasi Zenith Satellite System);
   • GLONASS
   • BDS
   • Galileo
   • U-TDOA
   • E-OTD
   • IPDL-OTDOA
   • Network Assisted GNSS (e.g. Network Assisted GPS or Network Assisted GALILEO)
   • UE ambient condition sensors-based positioning
     • Motion sensors (e.g. accelerometers, gyroscopes)
     • Environmental sensors (e.g. barometer)
     • Position sensors (e.g. magnetometers, orientation sensors)
   • TBS
   • Beacon identity for location lookup (e.g. WiFi access points or BLE beacons)
   • RF Pattern Matching
   • Methods using cell site or sector information and Timing Advance or RoundTrip Time measurements.
5. The location determining process should be able to combine diverse positioning techniques and local knowledge when considering quality of service parameters to provide an optimal positioning request response.
6. It should be possible to provide position information to location services applications existing within the PLMN, external to the PLMN, or in Mobile Equipment;
7. Support should be provided for networks based on Intelligent Network architecture (i.e. with specific support for CAMEL based Location Services).
8. Support may optionally be provided to enable the routing of emergency calls based on the geographic coordinates (latitude and longitude) of the calling party.
9. It shall be possible to provide the originating party's serving cell id to the LCS client.

Location Information consists of Geographic Location, Velocity, Civic Location and Quality of Service information, as described in the subsequent sections.

Reliability provides a measure of how often positioning requests that satisfy QoS requirements are successful. For some applications, such as cross-country vehicle tracking, this may not be especially critical. If a positioning attempt fails, due to lack of coverage or transient radio conditions, etc, another positioning attempt may be made. This attempt should be specified in Location Service Request. (see the clause 5.3.1.1). However, for other services, perhaps such as child tracking, reliability may be more important. The network shall provide statistical reporting of reliability (QoS parameters) data.

Location requests for different services may be processed with different levels of priority. For Value Added Services, and PLMN Operator Services, the following is applicable: The LCS Server may allow different location requests to be assigned different levels of priority. A location request with a higher priority may be accorded faster access to resources than one with a lower priority and may receive a faster, more reliable and/or more accurate location estimate. For Emergency Services (where required by local regulatory requirements) the location request shall be processed with the highest priority level.

For Value Added Services, and PLMN Operator Services, and Emergency Services (where required by local regulatory requirements), the LCS Server shall timestamp all location estimates or Dispatchable Location provided to a LCS Client indicating the time at which the estimate was obtained.

Specific local, national, and regional security regulations must be complied with. Position information should be safeguarded against unapproved disclosure or usage. Position information should also be provided in a secure and reliable manner that ensures the information is neither lost nor corrupted. Audit records should be maintained of positioning requests and responses to facilitate resolution of security violations. The LCS Client may be authorized by the LCS Server. Existing security mechanisms as well as security mechanisms of the LCS Server shall be used for authorizing the LCS Client and its request for location information. The target UE user shall be authenticated before being allowed to access (to modify/query) her personal data or query/cancel an LCS request. For Value Added Services, the following is applicable: Only authorized LCS Clients shall be able to access the LCS Server. Before providing the location of a Target UE to any authorized LCS Client, the LCS Server shall verify both the identity and authorization privileges of the LCS Client . Once the LCS Server has verified that a particular LCS Client is authorized to locate a particular Target UE, any location estimate or Dispatchable Location requested shall be provided to the LCS Client in a secure and reliable manner, such that the location information is neither lost, corrupted nor made available to any unauthorized third party. For PLMN operator services, location information shall be provided in a secure and reliable manner. The ability to obtain location information shall depend on local regulatory laws and requirements in conjunction with requirements for UE privacy. For Emergency Services (where required by local regulatory requirements) the following requirements shall be met: Position information shall be provided to the Emergency Services Network as an authorized LCS client. Target UE authorization checks normally performed for value added services are not applicable (privacy is over-ridden). The position information shall be provided to the Emergency Services Network in a secure and reliable manner, such that the location information is neither lost, corrupted, nor made available to any unauthorized third party.

Specific local, national, and regional privacy regulations must be complied with, and multiple layers of permissions may be required. Location information must always be available to the network service provider. Means shall be provided for the UE subscriber to control privacy for value added services. The user shall be able to change the setting of the Privacy exception list at any time. Unless required by local regulatory requirements, or overridden by the target UE User, the target UE may be positioned only if allowed in the UE subscription profile. In general, for valued added location services, the target UE being positioned should be afforded the maximum possible privacy, and should not be positioned unless the positioning attempt is explicitly authorized. In the absence of specific permission to position the target UE, the target UE should not be positioned. It may also be possible for a target UE to authorize positioning attempts after the target UE is notified of a positioning request and the target UE grants permission for positioning. It shall also be possible to make the notification conditional on the current location of the target UE. In this case the notification shall be performed after the target UE is positioned but before reporting the location of target UE to LCS Client. This notification condition (notification with privacy verification) shall be specified in the Target UE Subscription Profile. (See the subsequent "target subscriber notification" section of this document for charging and billing aspects.) The operator shall be able to determine the location of the target UE (e.g. for lawful interception or emergency call). The privacy of an inanimate asset for an embedded target UE may be completely defined by the UE subscriber. Additionally, specific privacy exceptions may exist for compliance with mandated location-based services (such as for emergency services or lawful intercept) which are required by national or local regulatory requirements. For Value Added Services, the following is applicable: The Target UE Subscriber shall be able to restrict access to the Location Information (permanently or on a per attempt basis). The LCS Client access shall be restricted unless otherwise stated in the Target UE Subscription Profile. The home network shall have the capability of defining the default circumstances in which the Target UE's Location Information is allowed to be provided - as required by various administrations and/or network requirements. The privacy check shall be performed in the Home Environment of the target UE subscriber. This makes it possible for operators to ensure the privacy of their own subscribers i.e. the privacy settings that are used for privacy checks are always up to date and as specified by the Home Environment of the target UE subscriber. It shall be possible for privacy check to take into account Home Environment specific information such as time of day, subscriber location. It shall be possible to ensure that privacy checks are performed according to the latest information as available in the Home Environment. It shall be possible for location services to support conditional positioning. Under these conditions, an application that is granted conditional positioning authorization must notify and obtain positioning authorization from the user of the target UE prior to performing the positioning process. Thus, the user of the target UE shall be able to accept or reject the positioning attempt. It shall be possible for location services to support conditional reporting if the target UE is within specified geographical areas. Under these conditions, an application that is granted conditional positioning authorization must notify and obtain positioning authorization from the user of the target UE after the positioning process is preformed but before reporting the location of the target UE to the LCS Client The default treatment, which is applicable in the absence of a response from the Target UE, shall be specified in the Target UE Subscription Profile. Thus, for some location services the default treatment may be to accept the positioning request, whereas for other location services the default treatment may be to reject the positioning attempt. However, considering that in general, users shall be afforded the maximum possible privacy, and shall not be positioned unless the target subscriber authorizes the requesting location application to perform positioning, the default condition shall normally be to deny the positioning attempt. For PLMN operator services, the target UE subscriber may be able to restrict access to location information used to enhance or support particular types of service. The LCS client access shall be restricted unless stated otherwise in the Target UE subscription profile. The target UE user shall not be notified of any authorized location attempt. For Emergency Services (where required by local regulatory requirements) Target UEs making an emergency call may be positioned regardless of the privacy attribute value of the subscriber associated with the Target UE (or ME) making the call. For Lawful Interception Services (where required by local regulatory requirements), target UEs may be positioned under all circumstances required by local regulatory requirements. The target UE user shall not be notified of any location attempt. All location requests (LRs) shall be done with a privacy check except for the following:

• LRs relating to lawful interception
• LRs related to emergency calls
• LRs from the serving network related to anonymous tracking for statistical and O&M purposes
• LRs from the home network as requested by the home network operator for its own internal purposes. The home network operator should not use the UE location information, which was obtained from the visited network without privacy checks, for value added services or to forward such location information to any third party (except for the cases of lawful interception or emergency calls).

Requests for positioning information should be processed only if the requesting application is authorized. The identity and authorization privileges of the requesting application should be verified prior to processing positioning requests.

To maximize the adoption of location services, the service activation process must be simple. Three types of service package, may be distinguished, each of which may require a different service activation process:

1. On Demand: the user accesses services only when required.
2. Period Subscription: the subscriber requires periodic availability of the service
3. Mixed: some services provided on subscription and the remainder on-demand.

The process of activation + service delivery + deactivation may be provided in a single transaction. It may be possible for a subscriber to activate a location service on one occasion before deactivating an existing invocation. Furthermore, a location service may be 'enabled' at the point of sale as part of the service package purchased by the UE subscriber. The use of Over-The-Air (OTA) provisioning may allow the location feature to be enabled for UE-based positioning methods.

In general a UE user should be able to access a location service anywhere within the operator's coverage area, or within the roaming area. Three levels of coverage may be considered:

1. Home Network - Complete
2. Home Network - Partial
3. Roaming Networks

Considering network topography and dynamically varying environmental factors, a network operator may not be able to guarantee homogeneous service quality across the entire home network geographic area, or roaming partners' networks. Even within those areas where service is offered, the provided quality of service may vary due to dynamic environmental (i.e. radio) conditions. Additionally, the location method may have an accuracy that depends on the UE location, for example due to varying radio conditions, cell configuration and cell density in different areas, and geometric dilution of precision. Furthermore, the roaming partner's network may not accept a similar location method to that experienced by the user in the home network. Finally, the service may not be available in a roaming partner's network despite technical interoperability between the location method supported by the UE and the network. Therefore, coverage may be considered not only to be a technical attribute, but may also be related to roaming contracts between network operators. In general, provided that a roaming agreement exists, any properly authorized location-based service may position a Target UE in either the Home PLMN (HPLMN) or a Visited PLMN (VPLMN). It may also be noteworthy that some location-based services (such as location-based information services) may be especially attractive to subscribers roaming outside their home networks.

With respect to roaming, specific local, national, and regional privacy regulations must be complied with, and multiple layers of permissions may be required. Many location-based services may be especially attractive to subscribers roaming outside their home PLMN. As such, support should be provided for the transparent and consistent provision of location-based services to the fullest extent possible. Consideration for roaming support should be provided with the following priorities:

1. Roaming between 3GPP networks.
2. Roaming between 3GPP systems and IMT 2000 family networks.
3. Roaming between 3GPP and ANSI-41 or other systems.

If the location capability in the VPLMN is compatible with that provided in the HPLMN, the same parameters must be provided to the location server in the VPLMN that would be provided to the server in the HPLMN to enable provision of the same services. For Value Added Services, the following is applicable: Provided that a roaming agreement exists, the LCS feature shall allow any properly authorized LCS client to request and receive the location of a particular Target UE when the Target UE is either located in its Home PLMN (HPLMN) or Visited PLMN (VPLMN). The LCS client shall be authorised by the HPLMN of the subscriber whose UE is the target of the location attempt. Any PLMN not supporting the LCS feature shall return a suitable error response to any other PLMN from which an LCS request is received. The requesting PLMN shall then infer that the LCS feature is not supported and provide a suitable error response in turn to the requesting LCS Client. For PLMN Operator Services, location of any roaming target UE shall be supported in the VPLMN as allowed by both local regulatory requirements and considerations, where applicable, of UE privacy. For Emergency Services (where required by local regulatory requirements) the Serving PLMN shall support the positioning of all Target UEs including roaming Target UEs currently serviced by that serving PLMN. There is no requirement for a HPLMN to position Target UEs that have roamed outside the HPLMN.

For value added services, and PLMN operator services, the LCS feature may be supported for all UEs. For Emergency Services (where required by local regulatory requirements), positioning shall be supported for all UEs (i.e. including legacy UEs) where coverage is provided, and also UEs without a SIM/USIM. In such a case, the location of the caller may be determined using the identity associated with the Mobile Equipment (ME) involved in the call. Both "active" and "idle" UEs shall be capable of being positioned.

For value added services, support of unauthorized UEs may be provided by the PLMN. For PLMN operator services, positioning of unauthorized UEs may be provided by the PLMN as required by local regulatory requirements. For Emergency Services (where required by local regulatory requirements), the PLMN shall support positioning for unauthorized UEs (i.e. including stolen UEs and UEs without a SIM/USIM).

Periodic location reporting is the act of the LCS Server initiating multiple position locations spread over a period of time. The periodic reporting function is generally applicable for asset management services and exists as several variants, each applicable to different value-added services:

• Location reporting only within predetermined period
  e.g. commercial asset tracking and, subject to provision of privacy, manpower planning.
• Periodic location reporting within specified period and reporting triggered by a specific event
  e.g. high value asset security, stolen vehicle monitoring, home zone charging.
• Periodic location reporting triggered by a specific event
  e.g. 24hr depot management, transit passenger information systems

Periodic location determination and reporting increases network traffic. However, scheduling the periods of location monitoring and reporting will reduce this. Finally, event-based logic provided by the network operator that monitors the asset (location and status) and only reports events that meet conditions agreed with the application may reduce network traffic further without reducing the QoS. If this event-based or time-based decision process is the responsibility of the application and not the network operator then all of the above services can be regarded as periodic location reporting. For value added services, and PLMN operator services, support of periodic location reporting may be provided by the PLMN. When an LCS client activates Periodic Location Reporting, the LCS server shall be able to inform the target UE of this activation according to the Privacy Exception List. Optionally, it may be possible for the target UE at any time to query the LCS server about any valid requests activated for that target UE, and/or cancel the request. When a request is cancelled by the target UE, the LCS server shall inform the LCS client of this cancellation. It should be possible for more than one LCS client to activate requests for the same target UE. For Emergency Services (where required by local regulatory requirements), there is no requirement for the PLMN to support periodic location reporting.

UE-Based Location Calculation may be supported on either a per-request basis or semi-autonomously whereby a single request from a UE subscriber enables UE based location calculation over an extended period without further interaction with the PLMN. For Commercial Services, the following may be applicable for semi-autonomous location:

The UE-Assisted Location Calculation is accomplished by network resources based upon radio ranging measurements provided by the UE. For Commercial Services, the following may be applicable for UE-Assisted location services:

Mobile Originating Location is the capability of the mobile station to obtain its own geographical location or have its own geographic location transferred to another LCS client. For Value Added Services, the following may be applicable: There are three classes of mobile originating location:

The provision of location services shall be possible without significantly adversely impacting the radio transmission or the signalling capabilities of the network.