11.2.2 Packet Control Acknowledgement

04.603GPPGeneral Packet Radio Service (GPRS)Mobile Station (MS) - Base Station System (BSS) interfaceRadio Link Control / Medium Access Control (RLC/MAC) protocolRelease 1999TS

This message is sent on the PACCH from the mobile station to the network. The message is formatted either as an RLC/MAC control block using the PACCH block format defined in 3GPP TS 04.04 or as 4 identical access bursts using the PACCH short acknowledgement block format defined in 3GPP TS 04.04. If sent as response to a Packet Polling Request message this latter message shall specify the format of the Packet Control Acknowledgement message. Otherwise the System Information parameter CONTROL_ACK_TYPE indicates which format the mobile station shall use. The order of bit transmission is defined in 3GPP TS 04.04. The numbering, assembling and field mapping conventions defined for RLC/MAC control blocks in sub-clause 10.0b shall apply.

The RLC/MAC control block format is shown in table 11.2.2.1 and table 11.2.2.2.

The access burst format is either 11-bit or 8-bit and is coded as shown in Table 11.2.2.1. The mobile station shall use the format indicated by the System Information parameter ACCESS_BURST_TYPE. The mobile station shall transmit the access burst four times, one time in each TDMA frame of the uplink radio block.

Message type: PACKET CONTROL ACKNOWLEDGEMENT

Direction: mobile station to network

Table 11.2.2.1: PACKET CONTROL ACKNOWLEDGEMENT

< Packet Control Acknowledgement message content > ::= — RLC/MAC control block format

< TLLI : bit (32) >

< CTRL_ACK : bit (2) >

< padding bits > ;

< Packet Control Acknowledgement 11 bit message > ::= — 11-bit access burst format

< MESSAGE_TYPE : bit (9) == 1111 1100 1 >

< CTRL_ACK : bit (2) > ;

< Packet Control Acknowledgement 8 bit message > ::= — 8-bit access burst format

< MESSAGE_TYPE : bit (6) == 0111 11 >

< CTRL_ACK : bit (2) > ;

Table 11.2.2.2: PACKET CONTROL ACKNOWLEDGEMENT

TLLI (32 bit field)
This field contains the TLLI of the mobile station. This field is encoded as defined in sub-clause 12.16.

CTRL_ACK (2 bit field)
This field contains acknowledgement information for the group of RLC/MAC control blocks that make up an RLC/MAC control message. The mobile station shall set the CTRL_ACK field to indicate which segments of an RLC/MAC control message have been received by the time of transmission of the PACKET CONTROL ACKNOWLEDGEMENT message.

This field can also be coded to contain the information if the mobile station is requesting the establishment of new TBF. This coding is allowed only when the message is sent in access burst format as a response to the PACKET UPLINK ACK/NACK message with Final Ack Indicator set to ‘1’ and TBF Est is set to ‘1’.

If the PACKET CONTROL ACKNOWLEDGEMENT message is being transmitted in response to a valid RRBP field received as part of an RLC/MAC block with Payload Type equal to ’10’, the CTRL_ACK field shall be set according to the following table:

bit

2 1

0 0 in case the message is sent in access burst format, the same meaning as for the value ’11’ except that the mobile station is requesting new TBF. Otherwise the bit value ’00’ is reserved and shall not be sent. If received it shall be intepreted as bit value ’01’.

0 1 the MS received an RLC/MAC control block addressed to itself and with RBSN = 1, and did not receive an RLC/MAC control block with the same RTI value and RBSN = 0.

1 0 the MS received an RLC/MAC control block addressed to itself and with RBSN = 0, and did not receive an RLC/MAC control block with the same RTI value and RBSN = 1. This value is sent irrespective of the value of the FS bit.

1 1 the MS received two RLC/MAC blocks with the same RTI value, one with RBSN = 0 and the other with RBSN = 1.

If the PACKET CONTROL ACKNOWLEDGEMENT message is being transmitted in response to a valid RRBP field received as part of an RLC/MAC block with Payload Type not equal to ’10’, the CTRL_ACK field shall be set to the value ’11’ in case the message is sent in normal burst format or in case the mobile station is not requesting new TBF. In case the message is sent in access burst format and the mobile station is requesting new TBF, the CTRL_ACK field shall be set to the value ’00’.

If the PACKET CONTROL ACKNOWLEDGEMENT message is being transmitted in response to a polling request in an IMMEDIATE ASSIGNMENT message received on CCCH, the CTRL_ACK field shall be set to the value ’11’.

If the mobile station receives an RLC/MAC block with Payload Type equal to ’10’ and RLC/MAC block with Payload Type not equal to ’10’ with different RRBP values such that they specify the same uplink block, the mobile station shall set the CTRL_ACK field according to the group of RLC/MAC control blocks that the RLC/MAC block with Payload Type equal to ’10’ belongs.