 experiencing slightly degraded throughputs, depending on the predetermined configuration). Thus, setting the GPRS default territory to a higher level will tend to increase the QoS experienced by the GPRS users. There is a downside to increasing the default GPRS territory, however. One issue is that there will be a tendency for increasing numbers of intracell handovers of circuit switched users to occur, with the aim of keeping the GPRS default territory free for the GPRS. As stated above, this will happen despite the fact that the GPRS load may be low. The second issue relates to the number of timeslots available per PCU. This number is fixed, and the overall system GPRS capacity may be affected if large numbers of GPRS timeslots are taking up PCU connections when not actually carrying GPRS traffic. There is, therefore, a compromise between the effects. Overall, it is initially recommended that the default territory is set to a level a little below the anticipated load level, as a compromise between the above factors. Territory Upgrade/Downgrade The GPRS territory upgrade and downgrade procedures are triggered under the following circumstances. Radio Network Planning and Optimisation GPRS Downgrade There are two dominant scenarios under which GPRS downgrade occurs: If the circuit switched (CSW) territory were to become fully occupied and it was necessary to ac- commodate a further CSW connection, then a timeslot from the GPRS territory would need to be re-allocated. This is a process that involves signalling between the CS RRM and the PCU, and also on air to the GPRS user(s) occupying the appropriate timeslot, and is therefore subject to delay. In order not to pass on this delay to the CSW user, the system tries to keep one or more timeslots (depend- ing on the number of carriers per cell) free for such CSW allocations. Where the CSW traffic load steadily increases, therefore, there will be a continuous increase in the CSW territory, with timeslots being re-allocated from the GPRS territory, ideally in advance o