scope:

The present document specifies the procedures used at the radio interface (Reference Point Um, see ETSI TS 101 376-4-2 [6]) for the GMR-1 General Packet Radio Service (GMPRS-1) Medium Access Control/Radio Link Control (MAC/RLC) layer.

The present document is applicable to the following GPRS Um functional layers:

• Radio Link Control functions;

• Medium Access Control functions; and

• Physical Link Control functions.

The procedures described in the present document are for the RLC/MAC functions of the GMPRS radio interface (Um) when operating on a Packet Data Channel (PDCH).

The present document provides the overall description for RLC/MAC layer functions of the general Packet Radio Service (GMPRS) radio interface Um. ETSI TS 101 376-3-22 [5] contains an overview of the GPRS radio interface (Um).

ETSI TS 101 376-4-3 [7] and ETSI TS 101 376-4-4 [8] contain the definition of the control channels used in the present document.

ETSI TS 101 376-4-7 [10] contains a description in general terms of the structured functions and procedures of this protocol and the relationship of this protocol with other layers and entities.

ETSI TS 101 376-4-8 [11] contains the definition of GMR-1 3G RLC/MAC procedures when operating on the Common Control Channel (CCCH).

ETSI TS 101 351 [12] contains functional procedures for the Logical Link Control (LLC) layer.

Application to interface structure

The RLC/MAC procedures apply to the interface structures defined in ETSI TS 101 376-4-3 [7]. They use the functions and services provided by layer 1 defined in ETSI TS 101 376-4-4 [8]. ETSI TS 101 376-4-7 [10] gives the general description of layer 3 including procedures, messages format and error handling.

Use of logical control channels

The logical control channels are defined in ETSI TS 101 376-5-2 [13]. Two similar sets of logical channels are defined. The first set consists of the logical channels:

• Broadcast Control Channel (BCCH): downlink only, used to broadcast Cell specific information;

• Paging Channel (PCH): downlink only, used to send page requests to Mobile Earth Stations (MESs);

• Random Access Channel (RACH): uplink only, used to request GPRS resources or a Dedicated Control Channel;

• Access Grant Channel (AGCH): downlink only, used to allocate GPRS resources or a Dedicated Control Channel.

The second set consists of the logical channels:

• Packet Random Access Channel (PRACH): uplink only, used to request GPRS resources;

• Packet Access Grant Channel (PAGCH): downlink only, used to allocate GPRS resources;

• Packet Associated Control Channel (PACCH): bi-directional, associated with a Temporary Block Flow (TBF);

• Packet Timing advance Control Channel Uplink (PTCCH/U): used to transmit Packet Normal bursts to allow estimation of the timing advance for one MES in transfer state;

• Packet Timing advance Control Channel Downlink (PTCCH/D): used to transmit timing advance updates for several MES. One PTCCH/D is paired with several PTCCH/Us.