ETSI STC SMG2 #36																		Tdoc SMG2 1035/00
Biarritz, France																					Agenda item 6.1
22 - 26 May 2000

Source: 	Nokia
Title:						Stage 2 description of location services in GERAN, (R00)

Summary: 
This contribution is a first draft proposal for the Stage 2 specification on Location services in GERAN in Release 2000. A contribution to S2 this week contains a first draft proposal on the corresponding  functional stage 2 description of location services in UMTS and GSM (Tdoc 2-001108), system and core network aspects, based on TS 23.171 and the system and core network parts of GSM 03.71. In 3GPP the LCS support in UTRAN is described in a separate Stage 2 specification TS 25.305. 
This contribution on LCS support in GERAN includes descriptions of both Circuit Switched and Packet Switched services. 
Proposal
It is proposed that SMG2 evaluates this presented Stage 2 specification on Location Services in GERAN for approval as an initial draft. 
It is also proposed that SMG2 evaluates the proposed LCS specification structure in Release 2000: 
•	One common LCS System and Core network stage 2 specification for GSM and UMTS (an initial draft proposal exists, but this is not yet approved in S2/SMG12)
•	Separate Stage 2 specifications on LCS support in different Access Networks: 
- TS xx.xxx LCS support in GERAN, new specification (this contribution) 
- TS 25.305 LCS support in UTRAN, to be revised for Release 2000 (3GPP R2)
Possible SMG2 comments on the proposed LCS specification structure should preferably be communicated to the S2 meeting #13 during this week. 
The numbering of this specification series should be resolved.

<Workitem> V<m.t.e> (2000-05>)
Technical Specification
Digital cellular telecommunications system (Phase 2+);
GSM/EDGE Radio Access Network (GERAN);
Location Services in GERAN;
Stage 2;
(GSM 03.59 version 0.0.1 Release 2000)

Reference
<Workitem>
Keywords
<keyword[, keyword]>

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Contents
Foreword	5
1	Scope	5
2	References	5
2.1	Normative references	5
2.2	Informative references	5
3	Definitions and abbreviations	6
3.1	Definitions	6
3.2	Abbreviations	6
4	Main concepts	6
4.1	Assumptions	6
4.2	Standard LCS Methods	6
4.2.1	Timing Advance	6
4.2.2	Enhanced Observed Time Difference (E-OTD) positioning mechanism	6
4.2.3	Global Positioning System (GPS) positioning mechanism	7
5	GERAN LCS Architecture	7
5.1	LCS Operations	7
5.2	High-Level Functions	8
5.2.1	Co-ordination, Measurement and Calculation Functions	9
5.3	GERAN LCS Functional Entities	9
5.3.1	Internal Client Group	9
5.3.1.1	Internal GERAN Location Client Function (LCF)	9
5.3.2	GERAN System Handling group	9
5.3.2.1	GERAN Location System Control Function (LSCF)	9
5.3.2.2	GERAN Location System Operations Function (LSOF)	10
5.3.3	Positioning group	10
5.3.3.1	GERAN Position Radio Co-ordination Function (PRCF)	10
5.3.3.2	GERAN Position Calculation Function (PCF)	10
5.3.3.3	GERAN Position Signal Measurement Function (PSMF)	11
5.3.3.4	GERAN Position Radio Resource Management (PRRM)	11
5.4	Assignment of LCS Functional Entities to GERAN Elements	11
5.5	Functional Description of GERAN LCS Network Elements	11
5.5.1	BSC	11
5.5.2	SMLC	12
5.5.3	BTS	12
5.5.4	LMU	12
5.5.5	MS	12
6	Interfaces	13
6.1	Generic signalling model for LCS	13
6.1.1	Protocol layering	13
6.2 	A interface	13
6.2.1 	MSC – SMLC communication	13
6.3 	Gb interface	13
6.3.1 	SGSN – SMLC communication	13
6.4 	Iu-ps Interface	13
6.5 	Iur Interface	13
6.6 	Abis Interface	13
6.7 	Um interface	13
6.7.1 	Assistance Data Delivery to UE	14
6.7.2 	Error Handling	14
6.7.3 	Broadcast of Assistance Data	14
6.7.4 	Signalling Flow for Assistance Data Broadcast Using CBCH Service	14
6.7.5 	LCS Assistance Data Ciphering	14
6.7.6 	LCS Assistance Data Ciphering Algorithm	14
6.7.7  	Signalling between SMLC and a LMU	14
7	State description of GERAN network elements in LCS	14
7.1	State description for SMLC	14
7.2	State description for LMU	14
7.3	State description for BTS	14
7.4	State description for MS	14
7.5.1	MS in IDLE State	14
7.5.2	MS in dedicated state	14
8 Positioning procedures	15
8.1	TA based positioning	15
8.1.1	TA Positioning Procedure	15
8.1.2	Unsuccessful TA Positioning procedure	15
8.2	E-OTD and GPS Positioning Procedures	15
8.2.1	General procedures	15
8.2.2	Positioning for SMLC	15
8.2.3	Assistance Data Delivery	16
8.2.5 	Error handling	16
8.2.6	Broadcast of ASSISTANCE DATA	16
8.2.6.1 	Point-To-Multipoint Assistance Data Broadcast Flow	16
8.2.6.2 	Ciphering	16
8.2.6.3 	Algorithm	16
8.2.6.4 	Deciphering key control and delivery to MS	16
9 	Information storage	16
9.1	SMLC	16
10 	Operational aspects	16
10.1 	Charging	16
Annex A (informative): Definitions and Terms	17

Foreword
1	Scope
The present document specifies the stage 2 of the LoCation Services (LCS) feature in GERAN, which provides the mechanisms to support mobile location services for operators, subscribers and third party service providers.
The purpose of this stage2 specification is to define the GERAN LCS architecture, functional entities and operations to support location methods. This description is confined to the aspects of LCS within the GERAN and does not define nor describe the LCS entities or operations within the Core Network.
Location Services may be considered as a network provided enabling technology consisting of standardised service capabilities, which enable the provision of location applications. The application(s) may be service provider specific. The description of the numerous and varied possible location applications which are enabled by this technology are outside the scope of the present document. However, clarifying examples of how the functionality being described may be used to provide specific location services may be included.
This stage 2 specification covers the GERAN LCS functional model and entities, the location methods, state descriptions, and message flows.
2	References
The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
•	References are either specific (identified by date of publication, edition number, version number, etc.) or non‑specific.
•	For a specific reference, subsequent revisions do not apply.
•	For a non-specific reference, the latest version applies.
2.1	Normative references
[1]	3G TS 23.XXX: "Functional stage 2 description of location services in UMTS???".
[2]	GSM 01.04 (ETR 350): "Digital cellular telecommunication system (Phase 2+); Abbreviations and acronyms".
[3]	Technical Specification Group Services and System Aspects Service aspects; Terminology and Vocabulary within TSG-S1: Report and Recommendations, 28.7.99.
[4]	GSM 02.71: "Digital cellular telecommunications system (Phase 2+); Location Services (LCS); Service description, Stage 1".
[5]	GSM 03.71: "Digital cellular telecommunications system (Phase 2+); Location Services (LCS); (Functional description) - Stage 2".
[6]	GSM 03.32: "Universal Geographical Area Description".

2.2	Informative references

3	Definitions and abbreviations

3.1	Definitions
For the purposes of the present document, the terms and definitions given in 3G TS 22.101 and some of the terms and definitions in annex A apply.
3.2	Abbreviations
For the purposes of the present document, the GSM-related abbreviations given in GSM 01.04 apply.
4	Main concepts
A general description of location services and the service requirements is given in the specification 3G TS 22.071 [X].
By measuring radio signals the capability to determine the geographic location of the moile station (MS) shall be provided. The location information may be requested by and reported to a client (application) associated with the MS, or by a client within or attached to the Core Network. The location information may also be utilised internally by GERAN, for example to support features such as home location billing. The location information shall be reported in standard formats, such as those for cell based or geographical co-ordinates of the location of the MS.
It shall be possible for the majority of the MS (active or idle) within a network to use the feature without compromising the radio transmission or signalling capabilities of the GERAN.
Three positioning mechanisms are proposed for LCS: Timing Advance (TA), Enhanced Observed Time Difference (E-OTD), and Global Positioning System (GPS) assisted.
4.1	Assumptions
-	SMLC is either an integrated functionality in BSC or a standalone network element within GERAN. 
-	LMU which is integrated in BTS is supported in GERAN.  
-	Separate LMU communication over the Um is FFS.
4.2	Standard LCS Methods
4.2.1	Timing Advance
The TA is based on the existing Timing Advance (TA) parameter. The TA value is known for the serving BTS. To obtain TA values in case the MS is in idle mode a special procedure, not noticed by the GSM subscriber (no ringing tone), is set up. The cell-ID of the serving cell and the TA is returned as the result of the TA.  
TA may be used to assist all positioning mechanisms and is a fall-back procedure.
4.2.2	Enhanced Observed Time Difference (E-OTD) positioning mechanism
The E-OTD method is based on measurements in the MS of the Enhanced Observed Time Difference of arrival of bursts of nearby pairs of BTSs. For E-OTD measurement synchronization, normal and dummy bursts are used. When the transmission frames of BTSs are not synchronized, the network needs to measure the Relative or Absolute Time Differences (RTDs or ATDs) between them. To obtain accurate triangulation, E-OTD measurements and, for non-synchronized BTSs, RTD or ATD measurements are needed for at least three distinct pairs of geographically dispersed BTSs. Based on the measured E-OTD values the location of MS can be calculated either in the network or in the MS itself, if all the needed information is available in MS.
4.2.3	Global Positioning System (GPS) positioning mechanism
The Global Positioning System (GPS) method refers to any of several variants that make use of GPS signals or additional signals derived from GPS signals in order to calculate MS position.  These variants give rise to a range of optional information flows between the MS and the network.  One dimension of variation is where position calculation is performed: a) MS-based PCF or b) network-based PCF.  Another dimension is whether "assistance data" is required - irrespective of where position calculation is performed.  Examples of assistance data include differential GPS data; lists of satellites in view based on approximate MS position, etc.  A third dimension of variation is closely related to the preceding, namely, the origin and distribution of any assistance data.  For example, even while assistance data may be required of a GPS method, it may be optional that the assistance data originates from and is distributed within and by the PLMN, VPLMN, etc.
5	GERAN LCS Architecture
shows the general arrangement of the Location Service feature. This illustrates, generally, the relation of LCS Clients and servers in the core network with the GERAN. The definition and operation of LCS entities operating in the core network is outside the scope of the present document. The LCS entities within the GERAN communicate with the Core Network (CN) across the A, Gb and Iu-ps interfaces. Communication among the GERAN LCS entities makes use of the messaging and signalling capabilities of the GERAN.
As part of their service or operation, the LCS Clients may request the location information of Mobile Station. There may be more than one LCS client. These may be associated with the core network, associated with the GERAN, operated as part of a MS application or accessed by the MS through its access to an application (e.g. through the Internet).
Within the GERAN, the SMLC receives authenticated requests for LCS information from the core network across the A, Gb or Iu-ps interfaces. The SMLC may be a standalone network element or SMLC functionality which is integrated to the BSC. LCS entities then manage the GERAN resources, including the base station, the LMU, the MS and calculation functions, to estimate the location of the MS and return the result to the CN.

Figure 1 Functional LCS architecture in GERAN
5.1	LCS Operations
The schematic functional description of LCS operations is defined in [X].
Upon request from the LCS entities or for internal operations, the GERAN LCS functional entities will:
-	request measurements, typically from the MS and one or more BTS radio apparatus;
-	send the measurement results to the appropriate calculating function within GERAN;
-	receive the result from the calculating function within GERAN;
-	perform any needed co-ordinate transformations;
-	send the results to the LCS entities in the core network or to application entities within GERAN.
In the event that the client is internal to GERAN the request may be made directly to the GERAN LCS entities as the internal clients are considered to be "pre-authorised".
As part of its operation, the GERAN LCS calculating function may require additional information. This may be obtained by the function directly by communication with a database, or it may be through a request to GERAN LCS entities that will mediate the request and return of information from the appropriate database (or databases if more than one is needed to fulfil the requests).
There may possibly also be available independent information that is able to supply the location information directly, or may be able to supply auxiliary information to the calculation function. The GERAN LCS co-ordination function, as part of its activity to supervise the location process, may query the MS or other elements of the GERAN to determine their capabilities and use this information to select the mode of operation.
This general operation is outlined in the following (generic) sequence diagram Figure 2. This figure is not intended to show the complete LCS operation for GERAN, but to simply to outline the basis for operation.

Figure 2 General sequence for LCS operation

5.2	High-Level Functions
Several functional groupings may be defined to describe the LCS. These groupings occur in both the Core Network and the GERAN. The overall LCS functional grouping is described in reference [1]. Each grouping encompasses a number of functional components and functions.
The functions within the GERAN are described in more detail in the following subclauses of the present document.
Within GERAN the functional entities may be grouped as follows:
-	the Internal Client group;
-	the GERAN System Handling group;
-	the Positioning group.

5.2.1	Co-ordination, Measurement and Calculation Functions
These GERAN functions (including functions in the System handling and Positioning groups) provide the co‑ordination, measurement and calculation functions needed to provide a location estimate. The functions interface with the requesting application and select the appropriate location method and speed of response. The functions co‑ordinate the operations of the radio and measurement equipment to transmit the needed signals and to make the needed measurements. The measurements is made by a Location Measurement Unit (LMU) which is integrated in a BTS. [NOTE: LMU communication over the Um is FFS inGERAN].
The functions may also access databases or other sources of information appropriate for the location method. The functions also provide the calculation functions appropriate for the location method to estimate the MS location and the accuracy of the report. The functions may also make co-ordinate translations to the geographic co-ordinate system requested by the application. The functions also may record information on the usage of the LCS that may be used for administrative purposes (e.g. forwarded to a billing function in the Core Network). If needed by the location method, the functions will ensure the broadcast of information and gather and update information concerning GERAN operating parameters (e.g. timing of BTS transmissions) needed for LCS operations.
These entities are mainly concerned with the location method, controlling the radio equipment and performing the calculations to determine the location and thus may be associated with the SMLC in the GERAN. These functions may receive location requests from either the core network or from applications internal to the GERAN.
The GERAN LCS entities may also request the subscription and authorisation functions in the core network to authenticate an application or a MS subscription or to verify the subscriber privacy parameters.
These functions communicate with the core network across the A, Gb and Iu interfaces, with other entities in the GERAN across the Iur/ interface and with the BTS and LMU across the Abis interface and with the MS across the Um interface.
5.3	GERAN LCS Functional Entities
 
5.3.1	Internal Client Group
5.3.1.1	Internal GERAN Location Client Function (LCF)
The Location Client Function (LCF) represents a logical interface between the internal GERAN LCS applications and the LCS BSC Handling entities (e.g. the Location System Control Function (LSCF) in the BSC).
NOTE:	There is not necessarily a requirement for a LCCF (Location Client Control Function) for the GERAN Internal Client as is described for external clients in reference [1] (the system stage specification).
The GERAN may make use of location information for internal operations such as location assisted handover. In such a case, a LCF representing the internal GERAN LCS application may communicate with the LSCF to request and receive the location information.
5.3.2	GERAN System Handling group
5.3.2.1	GERAN Location System Control Function (LSCF)
The GERAN Location System Control Function in SMLC/BSC is responsible for co-ordinating location requests within the SMLC handling entity. This function manages call-related and non-call-related location requests and allocates network resources for handling them. This function "insulates" the Location clients in the Core Network from the detailed operation of the location method in order that the GERAN may be used by several types of core network and with several location methods.
The LSCF provides flow control between simultaneous location requests. Simultaneous location requests must be queued in a controlled manner to account for priority requests (e.g. for Emergency Clients). The details of the flow control, priority selection and queuing are beyond the scope of the present document.
The LSCF will select the appropriate location method based on the availability of resources and parameters of the location request. The LSCF co-ordinates resources and activities needed to obtain data (e.g. base station geographic co-ordinates) needed for the location method. It also records LCS BSC usage data for the location service request that may be passed to a Location System Recording Function (LSRF) or O&M function in the Core Network.
If the location technique requires the broadcast of system information, the LSCF initiates and maintains this activity through the Position Radio Co-ordination Function (PRCF). Broadcast information (such as the geographic co-ordinates of the base stations) may be required, for example, to support a Position Calculation Function (PCF) located in the mobile station. These broadcasts may also include other information (such as currently observable satellites) that may assist a MS in the use of external location services.
The information to be broadcast is selected based on the location techniques offered for use by the LCS and the needs of the MS. This broadcast information may be specially coded (i.e. encrypted) to ensure its availability only to subscribers of the service. The use of broadcasts or other methods for signalling to the MS may be selected based on the chosen location method.
The information to be broadcast could include, for example:
-	TBD
5.3.2.2	GERAN Location System Operations Function (LSOF)
The Location System Operations Function (LSOF) is responsible for provisioning of data, location capabilities, data related to clients and subscription (LCS client data and MS data), fault management and performance management of LCS within the BSC.
An LSOF may be associated with each entity. The LSOF interacts with Internal (OAM) Clients for administration and maintenance of the data.
5.3.3	Positioning group
5.3.3.1	GERAN Position Radio Co-ordination Function (PRCF)
The GERAN Position Radio Control Function manages a location request for a MS through overall co-ordination and scheduling of resources to perform location measurements. This function interfaces with the PSMF, the PRRM and the PCF. The PRCF determines the location method to be used based on the location request, the QoS, the capabilities of the GERAN, and the MS's capabilities. The PRCF also manages the needed radio resources through the PRRM. It determines which PSMFs are to be involved, what to measure, and obtains processed signal measurements from the PSMF.
Some location methods may involve measurements made at the MS. In this case the PRCF interfaces with the MS to obtain the measurements (or the location results if they have been determined by the MS). Some location methods may involve measurements or information from several sources, including radio units at several BTSs and involve a series of transmissions and receptions. The PRCF entity also provide ancillary measurements in case of network-assisted location method. Ancillary information may be extracted from navigating systems like GPS.
The PRCF forwards the signal measurement data to the PCF.
It is the function of the PRCF to co-ordinate the sequence of activities and compensate for failures (if they occur) to provide the location estimate.
5.3.3.2	GERAN Position Calculation Function (PCF)
The GERAN Position Calculation Function is responsible for calculating the location of the MS. This function applies an algorithmic computation on the collected signal measurements to compute the final location estimate and accuracy.
The PCF may also support conversion of the location estimate between different geographic reference systems. It may obtain related data (e.g.: base station geographic co-ordinates) needed for the calculation. There may be more than one calculating function available within, or associated with, the calculation function of the GERAN.
The Position Calculation Function is also responsible for estimating the accuracy of the location estimate.
5.3.3.3	GERAN Position Signal Measurement Function (PSMF)
The GERAN Position Signal Measurement Function (PSMF) is responsible for performing and gathering uplink or downlink radio signal measurements for use in the calculation of a MS's location. These measurements can be location related or ancillary.
There may be one or more PSMF within a GERAN and they may be located at the MS or a Location Measurement Unit (LMU). The PSMF, generally, may provide measurement of signals (i.e. satellite signals) in addition to measurements of the GERAN radio transmissions. The measurements to be made will depend on the selected location method.
5.3.3.4	GERAN Position Radio Resource Management (PRRM)
The GERAN Position Radio Resource Management entity is responsible for managing the effect of LCS operations on the overall performance of the radio network. This may ensure, for example, that the operation of the PSMF does not degrade the QoS of other calls. The PRRM handles following functions:
-	TBD
5.4	Assignment of LCS Functional Entities to GERAN Elements
The following Table 1 shows the generic configuration for different location methods, including network-based, mobile-based, mobile-assisted and network-assisted methods. With this approach both the network and the mobiles are able to measure the timing of signals and compute the mobile's location estimate. Depending on the applied location method it is possible to utilise the corresponding configuration containing all needed entities. For instance, if a network-based location method is applied, the entities that are involved in measuring the mobile's signal and calculating its location estimate are allocated to the network elements of the access stratum. On the other hand, in case mobile-based or network-assisted methods are used these entities should be allocated to the mobile station.
Table 1 Example Allocation of LCS Functional Entities to Network Elements
	MS	BTS	LMU	SMLC	BSC	
LCF	X			X		
LSCF				X	X	
PRCF				X	X	
PCF	X			X		
PRRM					X	
PSMF	X	X	X			
LSOF	X	X	X	X	X	

5.5	Functional Description of GERAN LCS Network Elements

5.5.1	BSC
SMLC functionality may be integrated in a BSC.
5.5.2	SMLC
The SMLC is either a separate network element of GERAN or integrated functionality in  BSC which contains functionality required to support LCS in one PLMN.
The SMLC manages the overall co-ordination and scheduling of resources required for the location of a mobile. It also calculates the final location estimate and estimates the achieved accuracy.
The SMLC may control a number of LMUs for the purpose of obtaining radio interface measurements to locate or help locate MS subscribers in the area that it serves. The SMLC is administered with the capabilities and types of measurement produced by each of its LMUs. The following measurements returned by an LMU to a SMLC have a generic status in being usable for more than one location method:
-	radio interface timing information.
The SMLC and GMLC are connected through the VMSC, MSC Server or SGSN. When either the VMSC or SGSN and GMLC are in different PLMNs, they are interconnected via the Lg interface.
5.5.3	BTS
LMU functionality may be integrated in a BTS. Separate LMU communication over the Um is FFS.
5.5.4	LMU
The LCS Measurement Unit (LMU) entity makes measurements (e.g. of radio signals) and communicates these measurements to the BSC (e.g. the PRCF). The LMU contains a PSMF and may also perform calculations associated with the measurements.
The LMU may make its measurements in response to requests (e.g. from the SMLC), or it may autonomously measure and report regularly (e.g. timing of BTS transmissions) or when there are significant changes in radio conditions (e.g. changes in the RTD.
There may be one or more LMUs associated with the SMLC and an LCS request may involve measurements by one or more LMUs. 
An LMU makes radio measurements to support one or more positioning methods. These measurements fall into one of two categories:
a)	Location measurements specific to one MS used to compute the location of this MS
b)	Assistance measurements specific to all MSs in a certain geographic area
All location and assistance measurements obtained by an LMU are supplied to the SMLC associated with the LMU. Instructions concerning the timing, the nature and any periodicity of these measurements are either provided by the SMLC or are pre-administered in the LMU.
The following assistance measurements obtained by an LMU have a generic status in being usable by more than one position method:
Radio Interface Timing measurements – comprise Absolute Time Differences (ATDs) or Real Time Differences (RTDs) of the signals transmitted by Base Stations, where timing differences are measured relative to either some absolute time difference (ATD) or the signals of another Base Station (RTD). 
5.5.5	MS
The MS interacts with the measurement co-ordination functions to make measurements of downlink signals. The measurements to be made will be determined by the chosen location method. 
The MS may also contain LCS applications, or access an LCS application through communication with a network accessed by the MS or an application residing in the MS. This application may include the needed measurement and calculation functions to determine the MS's location with or without assistance of the GERAN LCS entities. 
The MS may also, for example, contain an independent location function (e.g., GPS) and thus be able to report its location, independent of the GERAN transmissions. The MS with an independent location function may also make use of information broadcast by the GERAN that assists the function.

6	Interfaces
6.1	Generic signalling model for LCS
6.1.1	Protocol layering
6.2 	A interface
6.2.1 	MSC – SMLC communication
6.3 	Gb interface
6.3.1 	SGSN – SMLC communication	
6.4 	Iu-ps Interface
The Iu interface is used to communicate between the LCS functional entities in the Core Network and the LCS entities in the Access Network. This interface passes the location requests and responses from authenticated external and internal LCS applications between the LCS entities in the Core Network and the Access Network LCS entities. Support for LCS signaling over Iu is specified in [X].
6.5 	Iur Interface
BSC-to-BSC signalling for LCS support
6.6 	Abis Interface
BSC signalling to a LMU in BTS.
6.7 	Um interface
The Um interface is used to communicate among the LCS entities associated with the BSC, the MSs and the LMUs. The Um interface is also used to communicate between the LCS entities in the core network and the MS.
This interface may pass measurement requests and results to and from MS or the LMU.
The Um interface may also pass location requests from internal or external LCS Clients (Applications) at the MS. Note that these requests may require the services of the LCS entities associated with the core network to authenticate clients and subscriber subscriptions to aspects of the LCS.
The Um interface may also be used for broadcast of information that may be used by the MS for its LCS operations. This may, for example, include timing and code information about nearby BTS transmissions that may assist the MS in making its measurements.
The Um interface may also pass messages relating to changes or reporting of the data associated with the Location System Operations Function (LSOF) in the MS.
6.7.1 	Assistance Data Delivery to UE
6.7.2 	Error Handling 
6.7.3 	Broadcast of Assistance Data
6.7.4 	Signalling Flow for Assistance Data Broadcast Using CBCH Service
6.7.5 	LCS Assistance Data Ciphering
6.7.6 	LCS Assistance Data Ciphering Algorithm
6.7.7  	Signalling between SMLC and a LMU
7	State description of GERAN network elements in LCS
7.1	State description for SMLC 
7.2	State description for LMU 
7.3	State description for BTS 
7.4	State description for MS
7.5.1	MS in IDLE State
7.5.2	MS in dedicated state

8 Positioning procedures
8.1	TA based positioning
8.1.1	TA Positioning Procedure 
8.1.2	Unsuccessful TA Positioning procedure
8.2	E-OTD and GPS Positioning Procedures
8.2.1	General procedures
For any location request where the highest priority level is assigned and MS-based GPS positioning is not used, the SMLC functionality shall provide sufficient assistance data to a target MS to enable a location estimate or location measurements to succeed according to the required QoS on the first attempt. The SMLC shall not assume in this case that the target MS already possesses assistance data. For a lower priority location request or when MS-based GPS positioning is used, the SMLC may reduce the assistance data provided to a target MS on the first location attempt. 
8.2.2	Positioning for SMLC
This signaling flow is generic for all MS based or assisted location methods (MS Based E-OTD, MS Assisted E-OTD, GPS and Assisted GPS). The signaling flow applyes to integrated and standalone SMLCs.

Figure 3 Signalling flow within E-OTD method in GSM/EDGE RAN architecture

1.	The SMLC functionality in BSC or standalone SMLC determines possible assistance data and sends "RRLP MEASURE POSITION" request to the MS including the QoS and any assistance data. 
2.	Provided that location request is allowed from a privacy perspective, the MS performs the requested E-OTD or GPS measurements. If the MS is able to calculate its own location and this is required, the MS computes a location estimate based on E-OTD or GPS measurements. Any data necessary to perform these operations will either be provided in the RRLP MEASURE POSITION request or available from broadcast sources. The resulting E-OTD or GPS measurements or E-OTD or GPS location estimate are returned to the SMLC in a RRLP MEASURE POSITION response. If the MS was unable to perform the necessary measurements, or compute a location, a failure indication is returned instead.
8.2.3	Assistance Data Delivery
8.2.5 	Error handling
8.2.6	Broadcast of ASSISTANCE DATA
8.2.6.1 	Point-To-Multipoint Assistance Data Broadcast Flow
8.2.6.2 	Ciphering
8.2.6.3 	Algorithm
8.2.6.4 	Deciphering key control and delivery to MS
9 	Information storage
9.1	SMLC
10 	Operational aspects
10.1 	Charging

Annex A (informative):
Definitions and Terms