6 Message functional definitions and contents

3GPP44.071GSM/EDGE Location Services (LCS)Mobile radio interface layer 3 LCS specificationRelease 17TS

6.1 General

This subclause defines the structure of the messages of the layer 3 protocol defined in 3GPP TS 43.059. These messages are standard L3 messages as defined in 3GPP TS 24.007.

Each definition includes:

a) a brief description of the message;

b) a table listing the information elements in the order of their appearance in the message. In a sequence of consecutive IEs with half octet length, the first IE occupies bits 1 to 4 of octet N, the second bits 5 to 8 of octet N, the third bits 1 to 4 of octet N+1 etc.;

For each IE the table indicates:

1) the information element identifier, in hexadecimal notation, if the IE has format T, TV or TLV. If the IEI has half octet length, it is specified by a notation representing the IEI as a hexadecimal digit followed by a "-" (example: B-);

2) the name of the IE (which gives an idea of the semantics of the element), which is used in this and other specifications as a reference to the IE within the message;

3) the name of the type of the IE (which indicates the coding of the value part of the IE), and a reference to a description of the value part of the IE;

4) the presence requirement indication (M, C or O) for the IE, as defined in 3GPP TS 24.007;

5) the format of the IE (T, V, TV, LV, TLV) as defined in 3GPP TS 24.007;

6) the length of the IE (or permissible range of lengths), in octets, in the message, where "?" means that the maximum length of the IE is only constrained by the link layer protocol, and in the case of the facility IE by possible further considerations specified in 3GPP TS 43.059. This indication is non-normative.

c) subclauses specifying conditions for IEs with presence requirement C or O in the relevant message. Together with other conditions specified in the present document and 3GPP TS 43.059 defines when the IE shall be included or not, what non-presence of such IEs means, and (for IEs with presence requirement C) the static conditions for presence and/or non-presence of the IEs (see 3GPP TS 24.007).

6.2 Messages for location services control

Table 6.2 summarises the messages for location services control.

The logical DTAP LCS Information Request and DTAP LCS Information Report messages, that are used in LCS Stage 2 (3GPP TS 43.059), are transported using REGISTER, FACILITY and RELEASE COMPLETE messages.

If there exists no LCS transaction between LMU and SMLC, REGISTER message is used to deliver the logical message. If LCS transaction between LMU and SMLC exists, FACILITY message is used to deliver the logical message. RELEASE COMPLETE message is used to indicate that LCS transaction is not any more needed, LMU can also use this message to transport logical LCS Information Response message.

Table 6.2: Messages for location service control

Messages for location service control	Reference
FACILITY	6.3
REGISTER	6.4
RELEASE COMPLETE	6.5

6.3 Facility

This message is sent by the Location Measurement Unit (LMU) or the network to request or acknowledge a location service. It is used when information is to be conveyed and the transaction already exists, but is not to be released. The location service to be invoked, and its associated parameters, are specified in the Facility information element (see table 6.3).

Table 6.3: FACILITY message content

IEI	Information element	Type / Reference	Presence	Format	Length
	Location service Protocol discriminator	Protocol discriminator 7.2	M	V	1/2
	Transaction identifier	Transaction identifier 7.3	M	V	1/2
	Facility Message type	Message type 7.4	M	V	1
	Facility	Facility 7.5	M	LV	2-?
90	Release forbidden	Release forbidden 7.6	O	T	1

6.4 Register

6.4.1 Register (network to LMU direction)

This message is sent by the network to the location measurement unit to assign a new transaction identifier for location service control and to request or acknowledge a location service (see table 6.4.1).

Table 6.4.1: REGISTER message content (network to LMU direction)

IEI	Information element	Type / Reference	Presence	Format	Length
	Location service Protocol discriminator	Protocol discriminator 7.2	M	V	1/2
	Transaction identifier	Transaction identifier 7.3	M	V	1/2
	Register Message type	Message type 7.4	M	V	1
	Facility	Facility 7.5	M	LV	2-?
90	Release forbidden	Release forbidden 7.6	O	T	1

6.4.2 Register (LMU to network direction)

This message is sent by the location measurement unit to the network to assign a new transaction identifier for location service control and to request or acknowledge a location service (see table 6.4.2).

Table 6.4.2: REGISTER message content (LMU to network direction)

IEI	Information element	Type / Reference	Presence	Format	Length
	Location service Protocol discriminator	Protocol discriminator 7.2	M	V	1/2
	Transaction identifier	Transaction identifier 7.3	M	V	1/2
	Register	Message type 7.4	M	V	1
	Facility	Facility 7.5	M	LV	2-?

6.5 Release complete

This message is sent by the location measurement unit or the network to release a transaction used for location service control. It may also request or acknowledge a location service (see table 6.5).

Table 6.5: RELEASE COMPLETE message content

IEI	Information element	Type / Reference	Presence	Format	Length
	Location service Protocol discriminator	Protocol discriminator 7.2	M	V	1/2
	Transaction identifier	Transaction identifier 7.3	M	V	1/2
	Release Complete Message type	Message type 7.4	M	V	1
10	Cause	Cause 3GPP TS 44.018	O	TLV	4-32
11	Facility	Facility 7.5	O	TLV	2-?

6.5.1 Cause

This information element shall be included when the functional handling of the Cause IE is specified in the service description. If the functional handling of the Cause IE is not specified, the receiving entity may ignore the IE. The Cause IE used in location services is defined in 3GPP TS 44.018 in subclause 10.5.4.11 (only applicable Cause values are used).

6.5.2 Facility

This information element shall be included as required by the service description and the procedures defined in the present document and in 3GPP TS 43.059.