11.2.28a Packet DBPSCH Uplink Ack/Nack

3GPP44.060General Packet Radio Service (GPRS)Mobile Station (MS) - Base Station System (BSS) interfaceRadio Link Control / Medium Access Control (RLC/MAC) protocolRelease 17TS

This message is sent on FACCH, SACCH or SDCCH from the network to the mobile station to indicate the status of uplink RLC data blocks received.

Message type: PACKET DBPSCH UPLINK ACK/NACK

Direction: network to mobile station

Classification: DBPSCH message

Table 11.2.28a.1: Packet DBPSCH UPLINK Ack/Nack information elements

< Packet DBPSCH Uplink Ack/Nack message content > ::=

{ < MESSAGE_TYPE : bit (6) == 001001 >

< RB Id : bit (5) >

{ 0 | 1 < CONTENTION_RESOLUTION_TLLI : bit (32) >

{ 0 | 1 < G-RNTI extension : bit (4) > } }

{ 0 — TCH TBF mode

{ 0 – All data blocks acknowledged, no retransmission requested

| 1 < STARTING_SEQUENCE_NUMBER : bit (8) >

< RECEIVED_BLOCK_BITMAP : bit (128) > }

| 1 — DCCH TBF mode

{ 0 – All data blocks acknowledged, no retransmission requested

| 1 < STARTING_SEQUENCE_NUMBER : bit (4) >

< RECEIVED_BLOCK_BITMAP : bit (8) > } }

< padding bits > 

! < DBPSCH message part error : bit (*) = < no string > > } ;

Table 11.2.28a.2: Packet DBPSCH UPLINK Ack/Nack information element details

CONTENTION_RESOLUTION_TLLI (32 bit field)
The CONTENTION_RESOLUTION_TLLI field is present only if the network has decoded one of the uplink RLC data blocks containing the G-RNTI. The mobile station shall perform the contention resolution function if the G-RNTI information element is present. This field contains a G-RNTI, which is defined in sub-clause 12.16.

G-RNTI extension (4 bit field)
This field contains the extra 4 bits of the G-RNTI not included in the CONTENTION_RESOLUTION_TLLI field which are necessary to provide a unique identifier for contention resolution in Iu-mode. This field is present when an assigned G-RNTI is used during the contention resolution procedure.

RB Id (5 bit field)
This field contains the radio bearer identity of the mobile station’s radio bearer for which the uplink data transfer is acknowledged. This field is encoded as a binary number with range 0-31.

STARTING_SEQUENCE_NUMBER (8 or 4 bit field)
The SSN contains the value of V(R) when this information element was transmitted. This field is encoded as the binary representation of V(R).
Range 0 to 255 (8 bit field)
Range 0 to 15 (4 bit field)

RECEIVE_BLOCK_BITMAP (RBB) (128 or 8 bit field)
The RBB is a bitmap representing Block Sequence Numbers. The bitmap is indexed relative to SSN as follows:

BSN = (SSN – bit_number) modulo 256, for bit_number = 1 to 128 128 bit field).

BSN = (SSN – bit_number) modulo 16, for bit_number = 1 to 8 (8 bit field).

The BSN values represented range:

from (SSN – 1) mod 256 to (SSN – 128) mod 256 (128 bit field)

from (SSN – 1) mod 16 to (SSN – 8) mod 16 (8 bit field)

The value of each bit represents the acknowledgement status of the RLC data block with:

BSN = (SSN – bit_number) mod 256 (128 bit field)

BSN = (SSN – bit_number) mod 16 (8 bit field),

it is encoded as follows:

0 Negative acknowledgement

1 Positive acknowledgement