WCDMA Uplink System Capacity: A Singular Perturbation Approach
Résumé
We consider a WCDMA system with two types of calls: real time (RT) calls that have dedicated resources, and data on real time (BE) calls (i.e. best effort) that share system capacity. We consider reservation of some capacity resources for the BE traffic as well as any capacity left over from RT calls. Our analysis approach is based on modeling of the system as a two dimensional Markov chain, where the first correspond to the number of RT calls and the second to the number of BE calls in the system. In order obtain the steady state distribution of this system, we use a singular perturbation solution approach for approximating the steady state. Our approach gives a good approximation and relatively faster computation in comparison with our exact methods like spectral analysis [17]. Based on this analysis, we derive performance evaluation results regarding blocking of RT calls and sojourn time of BE calls, under different traffic characteristics. Finally, we extend our result to cover BE admission control. Here, we find the maximum BE arrival rate such that the sojourn time of BE calls not exceed a threshold.