Admission and flow control for multimedia CDMA

QoS guarantees for an integrated CDMA system can be provided by a combination of admission and flow control. The admission control restricts the number of users in the system such that QoS requirements for all calls can be met. The flow control balances the system interference on a slot-by-slot basis such that bit error rate requirements are met for all users and the real-time users are given the highest priority. In this paper, we analyze the scenario of a single-cell DS-CDMA system carrying both voice and WWW users. A new admission control is proposed and analyzed for Web browsing sessions. The challenge in designing admission control for Web users is due to the fact that the Web traffic description is based on heavy tailed distributions. Thus, an accurate estimate for the average offered rate for a Web session is hard to compute. Our proposed admission scheme adaptively modifies the admission threshold at each time slot based on new average load measurements. The admission threshold is computed such that the probability of session dropping is maintained below a prescribed value. The flow control mechanism is an extension of the one proposed by C. Comaniciu et al. (2000), who used the residual capacity from voice users to allocate resources for WWW users