8.75 User CSG Information (UCI)

29.2743GPP3GPP Evolved Packet System (EPS)Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for Control plane (GTPv2-C)Release 18Stage 3TS

User CSG Information (UCI) is coded as depicted in Figure 8.75-1. The CSG ID is defined in 3GPP TS 23.003 [2].

		Bits
	Octets	8	7	6	5	4	3	2	1
	1	Type = 145
	2 to 3	Length = n
	4	Spare				Instance
	5	MCC digit 2				MCC digit 1
	6	MNC digit 3				MCC digit 3
	7	MNC digit 2				MNC digit 1
	8	spare					CSG ID
	9 to11	CSG ID
	12	Access mode		spare				LCSG	CMI
	13 to (n+4)	These octet(s) is/are present only if explicitly specified

Figure 8.75-1: User CSG Information

For two digits in the MNC, bits 5 to 8 of octet 6 are coded as "1111".

The CSG ID consists of 4 octets. Bit 3 of Octet 8 is the most significant bit and bit 1 of Octet 11 is the least significant bit. The coding of the CSG ID is the responsibility of the operator that allocates the CSG ID by administrative means. Coding using full hexadecimal representation (binary, not ASCII encoding) shall be used.

Access mode values are specified in Table 8.75-1.

Table 8.75-1: Access mode values and their meanings

Access Mode	Values (Decimal)
Closed Mode	0
Hybrid Mode	1
Reserved	2-3

Leave CSG flag (LCSG) shall be set to "1" if UE leaves CSG cell/Hybrid cell, and in this case, the receiving node shall ignore the rest information in the IE.

CSG Membership Indication (CMI) values are specified in Table 8.75-2. CMI shall be included in the User CSG Information if the Access mode is Hybrid Mode. For the other values of Access Mode, the CMI shall be set to 0 by the sender and ignored by the receiver.

Table 8.75-2: CSG Membership indication (CMI)

CMI	Values (Decimal)
Non CSG membership	0
CSG membership	1

NOTE: Due to a specification oversight, the CMI values in the above table are reversed from the values of the CMI IE (see clause 8.79). Furthermore, the encoding is different between GTPv1 and GTPv2.