imits. However, MCS for both transmissions and re-transmissions can be affected by the mobile station memory. Parameters related to multi-BCF and common BCCH assume importance in an EDGE radio network. As mentioned before, EDGE-capable and non-EDGE-capable transceivers in a one sector can be configured to have only one BCCH. TBF parameter setting makes it possible for TBFs of GPRS and EDGE radio networks to be multiplexed dynamically on one time slot. However, this scenario should be avoided, as the performance suffers in both EDGE: NETWORK PLANNING AND OPTIMISATION the uplink and downlink. In the UL, GPRS performance suffers owing to the large amount of 8-PSK re-transmissions taking place, while in the DL, it is due to the GMSK modulations being used where 8-PSK is carrying higher data rates for EDGE. Parameters related to delay and throughput assume importance owing to higher sub- scriber expectations from an EDGE network. 6.3.3 Transmission Network Planning The transmission network planning process for an EDGE network is similar to that described in Chapter 3. However, owing to the higher data rates, there is a new functionality called 'dynamic Abis '*. Thus, the following concepts assume importance in the design of an EDGE transmission network: dynamic Abis dimensioning of dynamic Abis dimensioning of the PCU/BSC. Chapter 5 has already covered some aspects related to dimensioning of the PCU/BSC, SO here we focus on dynamic Abis and its dimensioning. The interface between the base station and the BSC is known as the Abis interface, as shown in Figure 6.3. In GSM/GPRS networks this interface is 'static'. As we saw in Chapter 3, in GSM/GPRS networks the transceiver channels are mapped onto the Abis PCM time slots. Each TCH uses two bits of PCM frame, and these two bits together are known as PCM sub-time slots. This is 'static' in nature because each TRX reserves its full capacity from the Abis interface constantly even if there are no active users in the air-interface. This makes dimensioning of the Abis interfa