11.2.6a EGPRS Packet Downlink 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 the PACCH from the mobile station to the network to indicate the status of downlink RLC data blocks received and to report the channel quality of the downlink. The mobile station may optionally initiate an uplink TBF or request a temporary suspension of the downlink TBF.

Message type: EGPRS Packet Downlink Ack/Nack

Direction: mobile station to network

Table 11.2.6a.1 : EGPRS Packet Downlink Ack/Nack information elements

< EGPRS Packet Downlink Ack/Nack message content > ::=

< DOWNLINK_TFI : bit (5) >

< MS OUT OF MEMORY : bit(1)>

{ 0 | 1 < EGPRS Channel Quality Report : < EGPRS Channel Quality Report IE > >}

{ 0 | 1 < Channel Request Description : >Channel Request Description IE > >}

{ 0 | 1 < PFI : bit(7) > }

{ 0 | 1 < EPD A/N Extension length index : bit (6) >

< bit (expanded_EPDAN_extension_length(val(EPD A/N Extension length index)))

& { < EPD A/N Extension Info > ! { bit** = <no string> }} > }

< EGPRS Ack/Nack Description : < EGPRS Ack/Nack Description IE >>

<padding bits > } ;

< EPD A/N Extension Info > ::=

{ { — Rel-5 extension

{ 0 | 1 < Iu mode Channel Request Description : < Iu mode Channel Request Description IE > > }

{ 0 | 1 < RB Id : bit (5) > }

{ 0 | 1 < Timeslot Number : bit (3) > } }

{ — Rel-6 extension

{ 0 | 1 < Extended Channel Request Description : < Extended Channel Request Description IE > > } }

{ — Rel-7 extension

< EARLY_TBF_ESTABLISHMENT : bit (1) >

{ 0 | 1 < Secondary Dual Carrier Channel Report : < EGPRS Channel Quality Report IE > } }

< spare bit >** } // ; — Truncation may occur between released versions of the protocol

— The receiver shall assume the value zero of any truncated bits

Table 11.2.6a.1a : expanded_EPDAN_extension_length function

/*

* The expanded_EPDAN_extension_length function returns the actual length of

* the EPD A/N Extension Info IE computed as follows:

* – if index_value >= 6 or the mobile station is NOT assigned a dual carrier

* configuration, the length is index_value +1 (for sizes ranging from 1 to 64 bits)

* – if index_value < 6 and the mobile station is assigned a dual carrier configuration,

* the length is index_value +65 (for "expanded" sizes ranging from 65 to 70 bits)

*

* The description of the function in ANSI C language is provided herein for illustration.

*

* Parameter:

* index: index ranging from 0 to 63 and representative of the actual IE size

*

* Returned value: actual (expanded) size of the IE

*

*/

unsigned char expanded_EPDAN_extension_length (unsigned char index)

{

/* Indicates whether the mobile station is assigned a DLDC configuration (1) or not (0) */

extern unsigned char DLDC_configuration;

unsigned char L;

if ((index >= 6) OR (DLDC_configuration == 0))

L = index + 1;

else

L = index + 65;

return (L);

}

Table 11.2.6a.2: EGPRS Packet Downlink Ack/Nack information element details

DOWNLINK_TFI (5 bit field)
This field contains the TFI of the mobile station’s downlink TBF. This field is defined in sub-clause 12.15. On DBPSCH, this field equals the radio bearer identity of the radio bearer to which this message applies.

EGPRS Ack/Nack Description IE (L bit field)
This information element is defined in sub-clause 12.3.1. The number of bits (L) available for Ack/Nack Description information element depends on the inclusion of channel quality reports and channel requests. L shall be set so that the entire EGPRS Packet Downlink Ack/Nack message evenly fits into an RLC/MAC control block. If a lower L covers the entire receive window, that L shall be used.

MS OUT OF MEMORY (1 bit field)
This field indicates that the MS has no more enough memory to perform Incremental Redundancy.

0 The MS has enough memory
1 The MS is running out of memory

Channel Request Description IE
This information element is defined in sub-clause 12.7. If a PFI field is included in this message, it relates to the TBF request contained in the Channel Request Description IE. Neither this IE nor the PFI field shall be included if the Extended Channel Request Description IE is included.

Iu mode Channel Request Description IE
This information element is defined in sub-clause 12.7a.

Extended Channel Request Description
This information element is defined in sub-clause 12.7b. This IE contains a request for one or more additional uplink TBFs and shall only be included if the mobile station and the network support multiple TBF procedures. If this IE is included, the Channel Request Description IE and PFI field in the message shall be omitted.

EGPRS Channel Quality Report IE
This information element is defined in sub-clause 12.5.1. For a mobile station with a dual carrier downlink assignment, this IE shall contain measurements corresponding to the downlink carrier which is paired with the uplink carrier on which this message is being sent.

PFI (7 bit field)
This field contains the PFI parameter identifying a Packet Flow Context relating to the resource request specified in the Channel Request Description IE. The PFI parameter is encoded as the contents of the PFI information element as defined in 3GPP TS 44.018. This field may be included if the network supports packet flow context procedures and if a Channel Request Description IE is included in the message. If this field is included but the Channel Request Description IE is omitted, this field shall be ignored.

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 on SFACCH is acknowledged. This field is not included when the EGPRS PACKET DOWNLINK ACK/NACK message is sent on DBPSCH. This field is encoded as a binary number with range 0-31.

Timeslot Number (3 bit field)
It contains the timeslot number of the timeslot on which the corresponding RRBP was received. This field shall be included if and only if the timeslot number of the PDTCH/SBPSCH on which the EGPRS PACKET DOWNLINK ACK/NACK message is sent is different from the timeslot number of each of the timeslots assigned to this TBF in the direction of this TBF. This field is encoded as the binary representation of the timeslot number as defined in 3GPP TS 45.002.

EARLY_TBF_ESTABLISHMENT (1 bit field)

This field indicates whether or not the channel request is meant to request pre-allocation of an uplink TBF:

0 The channel request is not meant to pre-allocate an uplink TBF.
1 The channel request is meant to pre-allocate an uplink TBF.

Secondary Dual Carrier Channel Report

This information element is described in sub-clause 12.5.1. For a mobile station with a dual carrier downlink assignment, this IE shall contain measurements corresponding to the downlink carrier which is not paired with the uplink carrier on which this message is being sent. This IE shall not be included by an MS with a single carrier downlink assignment.