Performance evaluation of priority-based call admission control in multi-service DS-CDMA cellular networks supporting VBR video traffic

This paper analyses the performance of priority based call admission control policies on the reverse link (mobile to cell-site) of DS-CDMA (direct-sequence code division multiple access) based cellular networks supporting VBR (variable bit rate) video traffic along with voice and data. Such analysis is important for estimating capacity requirements of competing services in multi-service DS-CDMA networks. In the first part of the paper, a channel utilization model is suggested for VBR video sources in which excess bits of compressed video frames are transported using an additional DS-CDMA channel. The main contribution is that an analytical expression is derived to compute the statistical multiplexing gain of such sources in DS-CDMA. In the second part of the paper, two priority-based call admission control policies are evaluated under the context of a multi-service DS-CDMA cellular network. System parameters such as call blocking probability and call dropping probability are analytically determined using multi-dimensional Markov chain analysis. A mixed loss-delay system is considered in which a rejected call from a real-time service is assumed to be lost, whereas, a denied request for the transmission of a non real-time. message may be queued. The main contribution is that the impact of user mobility is included in the analysis, and not only the active calls but also the queued calls may undergo handoffs.