Aymen. I. Zreikat

 Abstract

We present in this paper a concentric cell approach which is suggested by Motorola to improve GSM capacity by 20-40 % in addition to the 80 % provided by the Synthesizer Frequency Hopping (SFH) approach. This work is an extension of the well-known Underlay-Overlay scheme to any number of layers/zones. The blocking/loss probability of the network is derived and calculated such that the blocking/loss probability meets at least the operators' demands at all locations in the cellular network (< 2%). Hence, the network partitioning is optimized in terms of the nominal load for a standard channel assignment scheme and a new channel assignment scheme with reservation policy is presented. To improve the efficiency of the model, the mobility is introduced in different places of the downtown. The numerical results are given to show that the blocking/loss probability of the outer zones is more critical than the inner zone, however, the blocking/loss probability of the inner zone is always below the limit while the resources of the network are not used very effectively. This problem is solved in this paper by suggesting the reservation policy where all resources of the network are used very effectively while maintaining the blocking/loss probability within the limit to all zones. On the other hand, when the mobility is introduced, the system behavior becomes more realistic. When the load becomes high, we approximately reach a balanced load over the cell zones as well as the whole network. Different parameters that affect the performance are presented and discussed in this paper, such as; the reservation policy, the ratio of moving mobiles, the coverage and the speed of the mobile in different downtown areas. The curves for the loss probability and the utilization are shown to demonstrate this effect. Some of these curves are validated against real data taken from Ericsson AB, Jordan Branch.

submitted to Wireless Personal Communications, Springer (USA), Nov., 2009.