 from signalling. Traffic types determine the signalling needs. Unlike in GPRS networks where short messages increase the resource (PRACH/PAGCH) requirements for channel set-up, EDGE networks do not face such a problem because of enhanced data rates. However, in EDGE networks, signalling require- ments may be greater. This is because, if more and more users are able to get attached to the network using the same time slot even when the net load is constant (i.e. more users per time slot means less throughput per user), a decrease in TCH utilisation would take place during a TBF. If this TCH utilisation remains constant, more signalling channels are required, reducing the number of users getting connected to the network. Thus, the steps involved in the dimensioning of an EDGE radio network can be sum- marised as follows: CS and PS territories are identified. For the PS territory, the number of time slots in the default and dedicated modes should be defined. Total traffic load inclusive of CS and PS should be defined. Delay versus load factor should be studied. Rate reduction factor/parameter must be calculated. Number of TRXs required for supporting the traffic is calculated. Outputs of dimensioning can be: number of time slots required for voice traffic number of time slots required for data traffic number of time slots in default and dedicated territories average and maximum PS load average and minimum user throughput number of TRXs required to support the above parameters. Parameter Planning Apart from the parameters that have been discussed in earlier chapters, there are few ad- ditional parameters in EDGE radio networks. The most important ones are related to link adaptation and incremental redundancy. Once EGPRS has been enabled; the initial coding scheme is selected. LA parameters are dependent on the modulation and coding scheme selections, for both initial transmission and re-transmissions. Although the MCS selections are based on the BTS parameters, the MCS used for the transmission is based on the BLER l