Effect of Mobility on Guard Channel Based Call Admission Control Scheme in Cellular Networks

In cellular telephone system, some channels known as Guard Channels are used exclusively for handover calls. The impact of this is improvement in probability of successful handoffs. For efficient usage of these reserved channels knowledge of mobility patterns, channel occupancy time and rate of call arrival is required. The guard channel based call admission control scheme has some drawbacks, in particular when load is high and mobiles are moving at larger speed. As the relative speed of mobile terminals is increased which lead to more handoffs per call, the required number of reserved channels increases, this lead to less number of channels available for newly arriving calls. As a result the capacity drops. In this paper a analytical model is analyzed to study the effect of variation in mobility on system performance in terms of blocking probability of new calls, dropping probability of handoff calls and Grade of service (GoS).The studies shows that for a given value of QoS, system having cells with small radius or mobile terminals moving at high speed, has lower capacity than systems where mobiles have low mobility.