Delay quality-of-service driven resource allocation for relay-based OFDMA cognitive radio networks

This paper investigates the delay quality-of-service (QoS) driven resource allocation schemes for multiuser orthogonal frequency division multiple access (OFDMA) relay-based cognitive radio (CR) problems which satisfy both the total transmit power constrained by CR networks and the interference limitations required by the primary users. Here we introduce the concept of effective capacity, which is treated as the maximum throughput with systems´s delay requirements. Then, we develop an optimal strategy with respect to the joint subchannel and power allocation to maximize the effective capacity of the CR systems with delay-QoS guarantees subject to both average total power and average interference constraints. Rigorous proofs are provided to insure the optimality and efficiency for such resource allocation scheme which can avoid prohibitive computational burden caused by Mixed Integer Nonlinear Programming (MINLP). Numerical results demonstrate that our derived scheme has substantial advantages over other algorithms, which is feasible and efficient in real-time applications.