Cross-layer optimization for multi-class VSG CDMA in Rayleigh fading

In this paper, we propose a joint throughput maximisation design across Physical (PHY) and Call admission control (CAC) layer for multi-class VSG CDMA systems in a Rayleigh fading environment. The system model is accurately analysed and a new exact closed form of the PHY-layer constraint is derived. We show that it is possible to transform the set of the non-linear PHY-layer constraints into linear expressions of the admission region of CAC layer. This facilitates formulating a linear cost function, which is modeled by semi-Markov decision processes (SMDPs), and results in an accurate cross-layer optimisation design. With the proposed design, the maximum throughput is achieved by linear-programming approach as well as the QoS requirements of both layers are guaranteed. Based on the numerical results, the system performance are improved up to 50% in terms of throughput and blocking probability.