Admission control in frequency hopping GSM systems

Abstract

One way to improve the ability to handle offered traffic variations in a cellular system is to use soft capacity, i.e., to have an admission control algorithm that accepts new calls as long as the quality of the already ongoing calls is preserved. The increased flexibility in the use of the radio resources will increase the capacity in the system. In GSM, the operators continuously tighten their cell plans. Suggestions of going to a cluster size of 3 with the help of soft capacity exist. This paper investigates the performance of an admission control algorithm based on the number of active users in each cell. The purpose of the admission control algorithm is to block some calls in order to preserve the quality in the system. By means of simulations it is shown that a traffic load based admission control algorithm works well in a system with cluster size of 3. The results show that the method preserves the quality both when the traffic is uniformly and non-uniformly distributed. The system uses frequency hopping, discontinuous transmission and quality based power control.