Cross-Layer Design for Interference-Limited Spectrum Sharing Systems with Heterogeneous QoS

In this paper, we study the cross-layer resource allocation for the secondary users (SUs) supporting heterogeneous services in interference-limited spectrum sharing system. Two classes of SUs are considered: delay-tolerant SUs (DT-SUs) and delay- sensitive SUs (DS-SUs). With the queue theory, the delay requirements of DS-SUs are transformed into constant rate requirements. Unlike most previous works, this paper formulates the optimization problem by taking heterogeneous Quality of Service (QoS) of both primary users (PUs) and SUs into consideration. Moreover, based on the convex optimization theory, we propose the dual decomposition method in which the joint subcarrier assignment and power allocation are performed to achieve the optimal solution. To simplify the computation complexity, a suboptimal algorithm is proposed to decouple the optimization problem into two sub-problems. Simulation results show that the system performance achieved by using the proposed suboptimal algorithm is close to that achieved by the dual decomposition method.