ement and TS25-TS30 are used for TRX and BTS signalling). If the first user needs MCS-9, then 1.25 TS is * Note that this is a vendor specific feature. Transmission Network Planning and Optimisation Table 3.14 TCH required on Abis for EGPRS coding schemes Coding scheme Bit rate [bps] TCH required on Abis MCS-1 8 800 MCS-2 11 200 MCS-3 14 800 MCS-4 MCS-5 22 400 MCS-6 29 600 MCS-7 44 800 MCS-8 MCS-9 59200 required/used by him/her (refer to Table 3.14). Similarly, the second user will take another 1.25 TS. Thus, 24/1.25 will mean that only 19 users will be logged on at the same time, which is substantially lower than that of the GSM network. Not only that, these users might not be using the capacity optimally, i.e. some of them might be reading only the downloaded email. Taking this into account, it is beneficial to use a Dynamic Abis. By using the Dynamic Abis, the capacity is fully utilised. This means that when the user is reading the downloaded email, the TSs that are not being used by the user can be used by another user. Hence, by using the Dynamic Abis concept, the probability of the Abis capacity becoming a bottleneck reduced; hence utilisation is optimised. Dynamic Abis planning (DAP) is implemented as a software feature. Some aspects that may be helpful in dimensioning the dynamic Abis are: BSS achievable throughput. An Abis pool is a shared resource that can limit the throughput per RTSL. Hence RNP and TNP together should dimension together to achieve a BSS throughput. RTSL capacity (k). This is the amount of data transmitted through a fully utilised RTSL. This is dependent mainly on the average C/I distribution. Average user throughput (Nu). This is the average throughput perceived by the user. Therefore, if Nu TSs are allocated, then the average throughput can be approx imately (kNu). Reduction factor (RF). This is the measure of the congestion of the EGPRS network. Its value lies between 0 and 1. In a nearly saturated network, it is near to 0 and in less saturated network, it is closer to 1. The RF is 