Cross-Layer Adaptive Resource Allocation Algorithm with Diverse QoS Requirements for Single-Cell OFDMA Systems

The orthogonal frequency division multiple access (OFDMA) based communication system has been considered as the main trend of next-Generation communication system. But the existing resource allocation algorithm designed for such system is always with high complexity thus hard to be realized. To solve such problem with the constraints of spectrum efficiency and buffer state, a novel cross-layer resource allocation algorithm (RAA) is proposed in this paper. The goal of our RAA is to maximize the system throughput while satisfying several practical constraints, such as fairness among services, head of line (HoL) delay and diverse quality of service (QoS) requirements. Due to these constraints, finding the optimal solution becomes a NP-hard problem. Therefore in this paper a novel method to solve such problem with acceptable complexity is proposed within following steps: firstly, based on the link state we formulate the ideal subchannel allocation strategy as a convex optimization problem, which can be efficiently solved by our proposed lagrange multiplier technique subchannel allocation (LMTSA) algorithm; secondly, according to the obtained channel allocation matrix, a power allocation algorithm based on the water-filling power allocation (WPA) idea is deployed to get the optimal power allocation matrix combining with adaptive modulation and coding (AMC); finally, through a greedy algorithm, the ultimate subchannel and power allocation matrix can be obtained based on iterative method. The simulation results illustrate that we can achieve the higher throughput and better QoS performance than the widely-used maximum throughput (MT) algorithm and round robin (RR) algorithm.