11.2.6c Packet DBPSCH Downlink Ack/Nack Type 2

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 shall only be used when FLO is used. It is sent on ADCH from the mobile station to the network to indicate the status of downlink RLC data blocks received.

Message type: PACKET DBPSCH DOWNLINK ACK/NACK TYPE 2

Direction: mobile station to network

Table 11.2.6c.1: Packet DBPSCH Downlink Ack/Nack TYPE 2 information elements

< Packet DBPSCH Downlink Ack/Nack Type 2 message > ::=

< MESSAGE_TYPE : bit (6) == 000010 > — The same message type as for Packet DBPSCH Downlink Ack/Nack is — used since these two messages are mutually exclusive

< RB Id : bit (5) >

< EGPRS Channel Quality Report : < EGPRS Channel Quality Report IE > >

{ 0 — UDCH TBF mode

{ 0 — All data blocks acknowledged, no retransmission requested

| 1 < FLO Ack/Nack Description : < FLO Ack/Nack Description IE > > }

| 1 — CDCH TBF mode

{ 0 — All data blocks acknowledged, no retransmission requested

| 1 < STARTING_SEQUENCE_NUMBER : bit (4) >

< RECEIVED_BLOCK_BITMAP : bit (8) > } }

<padding bits > ;

Table 11.2.6c.2: Packet DBPSCH Downlink Ack/Nack TYPE 2 information element details

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

FLO Ack/Nack Description IE (x bit field)
This information element is defined in sub-clause 12.3.2.

STARTING_SEQUENCE_NUMBER (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 15

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 16, for bit_number = 1 to 8 (8 bit field).

The BSN values represented range:

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 16 (8 bit field),

it is encoded as follows:

0 Negative acknowledgement

1 Positive acknowledgement