Uplink Call Admission Control in Multi-services W-CDMA Network

The capacity of CDMA wireless network is usually studied considering two classes of services: real-time and best-effort. In this paper, we are interested in analyzing sharing between three classes of services: real-time (Wr), non-real-time (NRT) and best-effort (BE). A classical approach which is widely used in wireless networks is based on adaptively deciding how many channels to allocate to calls of a given class. The rational behind our idea is that the NRT class (e.g. FTP) requires a minimum transmission rate. The capacity allocated to NRT traffic includes a fixed portion of bandwidth as well as a dynamic part which is shared with RT service. In contrast, BE applications can adapt their transmission rate to the network's available resources. Hence, the best-effort applications can use only the unused resources of the NRT band. Using a spectral analysis approach, we compute the steady-state distribution of the calls number for those different classes which allows us to provide explicitly the performance measure. The QoS parameters of interest are primarily the blocking probability for both RT calls and NRT calls, and expected sojourn times for both NRT calls and BE calls. We finally provide numerical study to show the benefit of our capacity allocation method by providing a desired quality level of service for NRT services, and we propose some CAC policies for NRT and BE services.