This document specifies procedures for the following layers of the radio interface (Um reference point), the interface between the GSM/EDGE Radio Access Network (GERAN) and the Mobile Station (MS):

• Radio Link Control (RLC)
• Medium Access Control (MAC), including Physical Link Control functions

The procedures apply in A/Gb mode and may also apply in Iu mode.

The following documents provide information related to this document:

• 3GPP TS 43.064 contains an overview of the GPRS radio interface (Um reference point).
• 3GPP TS 44.003 specifies channel types, access capabilities and channel configurations at the Um reference point.
• 3GPP TS 44.004 specifies services offered by the physical layer of the Um reference point. It also specifies control channels. RLC and MAC use these services and control channels.
• 3GPP TS 24.007 specifies, in general terms, this protocol's structured functions, its procedures and its relationship with other layers and entities. It also specifies the basic message format and error handling applied by layer 3 protocols.
• 3GPP TS 44.018 specifies GPRS procedures when operating on the Common Control Channel (CCCH) or on dedicated channels.
• 3GPP TS 44.064 specifies the Logical Link Control (LLC) layer.
• 3GPP TS 43.051 is an overall description of the GSM/EDGE Radio Access Network (GERAN) in Iu mode.
• 3GPP TS 51.010-1 specifies test procedures for radio-interface signalling.

3GPP TS 45.002 defines four similar sets of logical control. The first set consists of the following logical control 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 Stations (MSs);
• 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 following logical control channels (Packet Control Channels):

• Packet Broadcast Control Channel (PBCCH): downlink only, used to broadcast Cell specific information (not used, see sub-clause 1.6);
• Packet Paging Channel (PPCH): downlink only, used to send page requests to Mobile Stations (MSs) (not used, see sub-clause 1.6);
• Packet Random Access Channel (PRACH): uplink only, used to request GPRS resources (not used, see sub-clause 1.6);
• Packet Access Grant Channel (PAGCH): downlink only, used to allocate GPRS resources (not used, see sub-clause 1.6);
• 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 random access bursts to allow estimation of the timing advance for one MS in transfer state;
• Packet Timing advance control channel downlink (PTCCH/D): used to transmit timing advance updates for several MS. One PTCCH/D is paired with several PTCCH/U's.
• MBMS Packet Random Access Channel (MPRACH): uplink only, used during the initial counting procedure for MBMS.

The third set consists of the following logical control channels (COMPACT control channels):

• COMPACT Packet Broadcast Control Channel (CPBCCH): downlink only, used to broadcast Cell specific information; This channel broadcasts the same information as the PBCCH, but has a different physical structure (see TS 45.002);
• COMPACT Packet Paging Channel (CPPCH): downlink only, used to send page requests to Mobile Stations (MSs) on a COMPACT control channel;;
• COMPACT Packet Random Access Channel (CPRACH): uplink only, used to request GPRS resources on a COMPACT control channel;
• COMPACT Packet Access Grant Channel (CPAGCH): downlink only, used to allocate GPRS resources on a COMPACT control channel;
• Packet Associated Control Channel (PACCH): see above;
• Packet Timing advance control channel uplink (PTCCH/U): see above;
• Packet Timing advance control channel downlink (PTCCH/D): see above.

The fourth set consists of the following logical control channels (EC-GSM-IoT control channels):

• Extended Coverage Broadcast Control Channel (EC-BCCH): downlink only, used to broadcast Cell specific information for EC-GSM-IoT;
• Extended Coverage Paging Channel (EC-PCH): downlink only, used to send page requests to Mobile Stations (MSs) that have enabled EC operation;
• Extended Coverage Random Access Channel (EC-RACH): uplink only, used to request EC-GSM-IoT resources;
• Extended Coverage Access Grant Channel (EC-AGCH): downlink only, used to allocate EC-GSM-IoT resources;
• Extended Coverage Packet Associated Control Channel (EC-PACCH): bi-directional, associated with an EC Temporary Block Flow (EC TBF);

3GPP TS 45.002 defines the following logical traffic channels used by RLC and MAC:

• Traffic Channel (TCH): bidirectional, carries encoded speech or user data using GMSK on a dedicated basic physical subchannel (DBPSCH). TCH can be full-rate (TCH/F) or half-rate (TCH/H).
• Octal Traffic Channel (O-TCH): bidirectional, carries encoded speech using 8-PSK on a DBPSCH. O-TCH can be full-rate (O TCH/F) or half-rate (O-TCH/H).
• Enhanced Traffic Channel (E-TCH): bidirectional, carries user data using 8-PSK on a DBPSCH.
• Packet Data Traffic Channel (PDTCH): downlink: carries user data using GMSK, 8-PSK, 16-QAM or 32-QAM with normal symbol rate, or QPSK, 16-QAM, or 32-QAM with higher symbol rate on a shared basic physical subchannel (SBPSCH) or a DBPSCH. PDTCHs can be full-rate (PDTCH/F) or half-rate (PDTCH/H).
• Packet Data Traffic Channel (PDTCH) uplink: carries user data using GMSK, 8-PSK, 16-QAM with normal symbol rate, or QPSK, 16-QAM, 32-QAM with higher symbol rate on a shared basic physical subchannel (SBPSCH) or a DBPSCH. PDTCHs can be full-rate (PDTCH/F) or half-rate (PDTCH/H).
• Extended Coverage Packet Data Traffic Channel (EC-PDTCH) downlink: carries user data using GMSK or 8-PSK on one or four PDCH(s).
• Extended Coverage Packet Data Traffic Channel (EC-PDTCH) uplink: carries user data using GMSK or 8-PSK on one or four PDCH(s).

Unless explicitly stated otherwise, the following conventions apply:

• The notations "further study", "FS" or "FFS" indicate the annotated text is not normative.
• "GPRS" refers to "GPRS and EGPRS".
• "EGPRS" refers to "EGPRS and EGPRS2".
• "EGPRS2" refers to "EGPRS2-A and EGPRS2-B".
• "PBCCH" refers to "PBCCH and CPBCCH".
• "PPCH" refers to "PPCH and CPPCH".
• "PRACH" refers to "PRACH and CPRACH".
• "PAGCH" refers to "PAGCH and CPAGCH".
• References to "PDCH" also apply to "SBPSCH" and vice-versa.
• "MBMS Assignment" refers to either "MBMS ASSIGNMENT (NON-DISTRIBUTION)" or "MBMS ASSIGNMENT (DISTRIBUTION)".

Independently of what is stated elsewhere in this and other 3GPP specifications, mobile station support for PBCCH, PCCCH and PACKET PSI STATUS is optional for A/Gb-mode of operation. The network shall never enable PBCCH and PCCCH. On PACCH the network may send Packet System Information (PSI) messages PSI13, PSI14 and PSI15 but shall not send any other PSI message.