Visual Media Coding and Transmission

8.2 GPRS/EGPRS Channel Simulator

The simulator model described in this section characterizes GPRS and EGPRS radio access network functionality. The main issues tackled are data flow across the radio access protocol stack and the effects of the physical link layer, which include forward error correction, modulation, transmission over fading channels, equalization and reception, and detection of correctable and uncorrectable errors. Power control mechanisms are not implemented in this model.

8.2.1 GSM/EDGE Radio Access Network (GERAN)

The GERAN system architecture is shown in Figure 8.1. GERAN is connected to the core network through the Iu and A interfaces. Services based on second-generation (2G) systems are supported by the 2G SGSN (Serving GPRS Support Node) and the 2G MSC (Mobile Switching Centre). The 3G SGSN and 3G MSC take responsibility for the support of third-generation mobile services. Each SGSN is in charge of several base station subsystems (BSSs). A BSS contains a base station controller (BSC) and one or more base transceiver stations (BTSs). The BCS monitors and controls the BTSs in its BSS. Mobile terminals (MTs) are connected to a BTS via the Um air interface [3]. GERAN uses the same air interface specified in GSM. Multiple access is based on the combination of TDMA and FDMA techniques [4]. Frequency bands have been reserved around 900 MHz for GSM 900 and around 1800 MHz for GSM 1800 for use in Europe. Allocated frequency bands are: 890–915 MHz (uplink) and 935–960 ...