Threshold Based Call Admission Control for QoS Provisioning in Cellular Wireless Networks with Spectrum Renting

Abstract

Radio spectrum is scarce and precious resource in wireless networks. To efficiently utilize radio spectrum, idle radio channels can be rented between various wireless networks and a wireless network renting out its idle channels can withdraw its radio channels when requiring its channels. However, the rental and withdrawal of radio channels result in two phenomena. One is the variation in the number of available channels in a wireless network, and the other is that a mobile user may be dropped due to the withdrawal. Threshold based call admission control, which uses an admission threshold to provide quality-of-service (QoS) guarantees for mobile users and maximize throughput, should include the two phenomena to select the optimal value of the admission threshold. In this paper, we study two call admission control schemes, namely, single-threshold call admission control and multiple-threshold call admission control, in a cellular wireless network with spectrum renting. We develop numerical analyses to analyze the performances of the two call admission control schemes, and apply the numerical analyses to select the optimal values of the admission thresholds in the two call admission control schemes such that the quality-of-services (in terms of hand-off dropping and withdrawal dropping probabilities) of mobile users are satisfied while throughput is maximized. Numerical results show that the multiple-threshold call admission control scheme outperforms the single-threshold call admission control scheme.