ance. As would be expected, the increase in blocking is more pronounced where there are few carriers per cell. The graph does show, however, that even dedicating just one or two timeslots to the GPRS in the case where there are relatively high numbers of carriers per cell can significantly affect the call blocking (e.g. 5 carriers, 38 TCHs: 2 % blocking increases to 3.5% when 2 TCHs are dedicated to the GPRS). There is, therefore, a compromise between providing a minimum GPRS service level and increasing the blocking probability for circuit switched services. Whether resources should be dedicated is dependent on the priorities of the network operator and the existing system performance. Unless there is an absolute Capacity Planning Circuit blocking probability vs no. of dedicated GPRS TCHs per 1 TCH 2 TCH 3 TCH No. TRXs Figure 2.25 Effect of dedicating traffic channels to the GPRS on the circuit switched blocking probability need to guarantee a minimum GPRS service (albeit at the expense of circuit switched blocking), where this might otherwise be unlikely (such as under very high circuit switched traffic levels), it would probably be better not to dedicate slots to the GPRS. Default GPRS Territory The default GPRS territory is an area that will always be included in the instantaneous GPRS territory should the circuit switched traffic level permit. If circuit switched traffic is decreasing, having occupied some of the GPRS default territory, then re-allocation of timeslots to the GPRS will occur automatically, independent of the actual GPRS load. Such timeslots will therefore be available immediately to GPRS users about to set up a call, or for a re-allocation of the existing users with the aim of increasing their data rates. Where circuit switched traffic levels are falling, but are outside the GPRS territory, then automatic re-allocation does not take place. The free timeslots made available in this case will only be requested should the GPRS load reach a predefined level (at which time the users may already be