GEO-Mobile Radio Interface Specifications (Release 3); Third Generation Satellite Packet Radio Service; Part 4: Radio interface protocol specifications; Sub-part 12: Mobile Earth Station (MES) - Base Station System (BSS) interface; Radio Link Control/Medi
The present document specifies the procedures used at the radio interface (Reference Point Um@ see GMR-1 04.002 [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. GMR-1 3G 43.064 [5] contains an overview of the GPRS radio interface (Um). GMR-1 04.003 [7] and GMR-1 3G 44.004 [8] contain the definition of the control channels used in the present document. GMR-1 3G 24.007 [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. GMR-1 3G 44.008 [11] contains the definition of GMR-1 3G RLC/MAC procedures when operating on the Common Control Channel (CCCH). 3GPP TS 04.64 [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 GMR-1 04.003 [7]. They use the functions and services provided by layer 1 defined in GMR-1 3G 44.004 [8]. GMR-1 3G 24.007 [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 GMR-1 3G 45.002 [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.