3GPP43.051GSM/EDGE Overall descriptionRelease 16Stage 2TS
The RLC/MAC data block headers for ECSD channel coding are identical in uplink and in downlink.
B.3.1 Uplink and downlink RLC/MAC data block header
The header formatting is depicted in Figure B-9.
Figure B-9. Downlink and uplink RLC/MAC Data Block Header using ECSD.
All header-fields in Figure B-9 except the P- and PT-fields follows the specification of GPRS and EGPRS. The Length Indicator is identical to the EGPRS Length Indicator, and the TFI is identical to the GPRS/EGPRS TFI field. The specification of the P- and PT-fields is included below.
Polling bit. This bit is set if the receiver is polled for an ACK/NAK report. P=0 implies that polling should be ignored, while P=1 requires that the receiver sends an ACK/NAK report to the transmitter.
Payload type. If PT=1 then the RLC/MAC block contains user data, and if PT=0 then the RLC/MAC-block contains control information.
Block check sequences are also defined for data blocks on ECSD channels. However, they are not shown in Figure B-9 since they are not considered to be part of the header. An 8-bit block check sequence is mandatory for the header while a 16-bit block check sequence is optional for the payload.
Whether the block check sequence on the payload is used or not is negotiated during service setup.
Annex C (informative):
RRC States, MAC States and RRC Connection Mobility