10.3 Skip indicator and transaction identifier
24.0083GPPCore network protocolsMobile radio interface Layer 3 specificationRelease 18Stage 3TS
10.3.1 Skip indicator
Bits 5 to 8 of the first octet of every Mobility Management message and GPRS MobilityManagement message contains the skip indicator.
With the exception of the following cases for a shared GERAN network in A/Gb mode,
– when the MS is sending a LOCATION UPDATING REQUEST, CM SERVICE REQUEST, IMSI DETACH INDICATION or CM RE-ESTABLISHMENT REQUEST message; or
– when the network is receiving a LOCATION UPDATING REQUEST, PAGING RESPONSE, CM SERVICE REQUEST, IMSI DETACH INDICATION or CM RE-ESTABLISHMENT REQUEST message,
the skip indicator field shall be handled as follows:
a) A message received with skip indicator different from 0000 shall be ignored. A message received with skip indicator encoded as 0000 shall not be considered an error that causes the message to be ignored.
b) A protocol entity sending a Mobility Management message or a GPRS Mobility Management message shall encode the skip indicator as 0000.
In a shared GERAN network in A/Gb mode:
a) When the MS is sending a LOCATION UPDATING REQUEST, CM SERVICE REQUEST, IMSI DETACH INDICATION or CM RE-ESTABLISHMENT REQUEST message,
– if the MS is a GERAN network sharing supporting MS, the MS shall encode the skip indicator IE to indicate the chosen PLMN identity from the PLMN identities in the broadcast system information (see 3GPP TS 44.018 [84]) according to table 10.3.1;
– otherwise, the MS shall encode the skip indicator as 0000.
b) When the network is receiving a LOCATION UPDATING REQUEST, PAGING RESPONSE, CM SERVICE REQUEST, IMSI DETACH INDICATION or CM RE-ESTABLISHMENT REQUEST message,
– if the skip indicator is encoded as 0000, the message shall not be considered an error that causes the message to be ignored;
– if the skip indicator is different from 0000, the message shall not be considered an error and shall be processed by the receiving MM entity. The MS shall be considered as GERAN network sharing supporting MS.
NOTE: The skip indicator handling of PAGING RESPONSE message on the MS and the BSS is specified in 3GPP TS 44.018 [84].
|
8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
||
|
Skip indicator |
– |
– |
– |
– |
octet 1 |
||||
Figure 10.3.1: Skip indicator
Table 10.3.1/3GPP TS 24.008: Skip indicator
|
Bits |
||||
|
8 |
7 |
6 |
5 |
|
|
0 |
0 |
0 |
0 |
Skip Indicator without indication of selected PLMN |
|
0 |
0 |
0 |
1 |
PLMN identity of the Common PLMN in the broadcast system information |
|
0 |
0 |
1 |
0 |
PLMN identity of the first Additional PLMN in the broadcast system information |
|
0 |
0 |
1 |
1 |
PLMN identity of the second Additional PLMN in the broadcast system information |
|
0 |
1 |
0 |
0 |
PLMN identity of the third Additional PLMN in the broadcast sytem information |
|
0 |
1 |
0 |
1 |
PLMN identity of the fourth Additional PLMN in the broadcast system information |
|
0 |
1 |
1 |
0 |
Reserved |
|
0 |
1 |
1 |
1 |
Reserved |
|
All other values shall be interpreted as "Skip Indicator without indication of selected PLMN". Value 0000 indicates no indication of selected PLMN from the MS, which happens in UTRAN, or non-shared GERAN or Multi-Operator Core Network (MOCN) with common GERAN configurations or in a shared GERAN if the MS does not support GERAN network sharing. |
||||
10.3.2 Transaction identifier
Bits 5 to 8 of the first octet of every message belonging to the protocols "Call Control; call related SS messages" and "Session Management"contain the transaction identifier (TI). The transaction identifier and its use are defined in 3GPP TS 24.007 [20].
For the session management protocol, the extended TI mechanism may be used (see 3GPP TS 24.007 [20]).
For the call control protocol, the extended TI mechanism shall be supported for the purpose of protocol error handling as specified in subclause 8.3.1