9.1.30c EC-SCH INFORMATION

3GPP44.018GSM/EDGE Radio Resource Control (RRC) protocolMobile radio interface Layer 3 specificationRelease 17TS

This message is sent on the EC-SCH, which is one of the broadcast channels (ref. 3GPP TS 45.002). Its purpose is to support the synchronization of an EC capable mobile station to a BSS when a cell supports EC operation (i.e. the presence of the EC-SCH indicates that EC operation is supported in the cell). It does not follow the basic format. Its length is 30 bits (see 3GPP TS 45.003). The order of bit transmission is defined in 3GPP TS 44.004. See figure 9.1.30c.1 and table 9.1.30c.1.

Message type: EC-SCH INFORMATION

Significance: dual

Direction: network to mobile station

Bit number

Octet no.

8

7

6

5

4

3

2

1

1

T1‘ (hi)

BSIC (hi)

2

T2‘ (hi)

T1‘ (low)

3

RACH Access Control

EC-BCCH CHANGE MARK

Implicit Reject Status

T2‘ (low)

4

BSIC (low)

IMM CGI

Figure 9.1.30c.1: EC-SCH INFORMATION message information elements, if sent in 51-multiframe M with M mod 8 = 0,1,2,3.

Bit number

Octet no.

8

7

6

5

4

3

2

1

1

T1‘ (hi)

BSIC (hi)

2

T2‘ (hi)

T1‘ (low)

3

RACH Access Control

EC-BCCH CHANGE MARK

Implicit Reject Status

T2‘ (low)

4

BSIC (low)

IMM CM

Spare

Figure 9.1.30c.1a: EC-SCH INFORMATION message information elements, if sent in 51-multiframe M with M mod 8 = 4,5,6,7.

Table 9.1.30c.1: EC-SCH INFORMATION message contents

BSIC, base station identity code is a 9 bit field identifying the base station (see 3GPP TS 45.002).

T1′ and T2′, these are 2 parts of the reduced TDMA frame number per quarter hyperframe (RFNQH) as specified in 3GPP TS 45.002[32].

RACH Access Control is a 1 bit field, is only applicable to mobile stations that have selected CC1 on both the uplink and downlink (i.e. all other mobile stations shall ignore this field) and is coded as follows:

0: A mobile station that has selected CC1 in both uplink and downlink shall use the EC_CCCH_GROUP (i.e. one of timeslots 1, 3, 5 or 7 – see 3GPP TS 45.002 [32]) to transmit the EC PACKET CHANNEL REQUEST

1: A mobile station that has selected CC1 in both uplink and downlink shall use timeslot 0 to transmit the EC PACKET CHANNEL REQUEST

EC-BCCH CHANGE MARK is a 3 bit field that operates as a modulo 8 counter and is therefore incremented each time the content of any of the EC SYSTEM INFORMATION messages is changed. An exception is when PLMN specific access barring is enabled (see sub-clause 3.5.2a) for a given set of PLMNs and changes are made only to the EC_Access_Control_Class field or the Exception_Report_Status field corresponding to this set of PLMNs in which case the EC-BCCH CHANGE MARK field is not incremented.

Implicit Reject Status is a 2 bit field and is coded as follows:

00: no barring

01: roamer barring enabled for all mobile stations that are neither in their HPLMN nor in a PLMN that is equivalent to it (see 3GPP TS 22.011 [6]).

10: roamer  barring enabled for all mobile stations that are neither in the PLMN listed as most preferred PLMN of the country where the MS is roaming in the operator-defined PLMN selector list on the SIM/USIM, nor in their HPLMN nor in an PLMN that is equivalent to it (see 3GPP TS 22.011 [6]).

11: all mobile stations barred. Only applies to MS with Access Class 0 to 9 (see 3GPP TS 22.011)

IMM CGI is a 3 bit field that provides the IMM Cell Group Identifier (see subclause 9.1.43q) and is coded as follows:

000: IMM Cell Group Definition is not broadcasted or not supported in the cell.

001: Cell belongs to IMM Cell Group Identity 1.

010: Cell belongs to IMM Cell Group Identity 2.

…

111: Cell belongs to IMM Cell Group Identity 7.

IMM CM is a 2 bit field that identifies the change mark of the IMM Cell Group (see subclause 9.1.43q) and is coded as follows, if IMM CGI has a different value from "000":

00: IMM Change Mark value is 0

01: IMM Change Mark value is 1

10: IMM Change Mark value is 2

11: IMM Change Mark value is 3

Otherwise, if IMM CGI has the value "000", these bits shall be ignored.