Research On OFDMA-based Cross-layer Scheduling Algorithm In Wireless Video Communication System

The rapid development of wireless network and the increasing growth of requirements formultimedia applications aggravate the conflicts between the finite wireless resources and the qualityof service (QoS) requirements of multimedia services. As a result, resource allocation strategywhich can improve overall network performance and support high-quality multimedia services isthe focus of current research in the field of wireless communications. Cross-layer based resourceallocation discards the layered designed and treats all the layers jointly, so it improves the utilizationefficiency of radio resources.The downlink of the LTE system adopts OFDMA multiple access technology, which canenhance the data rate while reducing interference greatly, and its design is sufficient to meet thedemand of multimedia applications. As video stream has very strict QoS requirements, it becomesextremely important to study the cross-layer resource scheduling problem in LTE system.Based on cross-layer design, the paper researches scheduling algorithm for downlink LTEsystem on how to protect the user’s QoS demand of video streams. Firstly, the paper studiescross-layer scheduling algorithm based on the utility function in LTE network. The goal of theutility function is to maximize the video quality for receiving end. To solve the optimizationproblem, the paper proposes a cross-layer resource allocation algorithm, which considers theparameters from application layer, MAC layer and physical layer. Meanwhile, in order to improvethe utilization of the resource blocks (RBs), the algorithm takes the user queue information intoaccount. Simulation results show that the cross-layer scheduling algorithm does better thanM-LWDF algorithm in packet loss rate, utilization of the resource block and PSNR performances.Secondly, this paper proposes a APP-MAC cross-layer resource scheduling algorithm which canguarantee delay of video streaming in LTE network. APP layer scheduler uses the discrete-timelinear control theory to design a low-complexity resource allocation algorithm, which transformsthe delay requirements of real-time video streaming to frame rate requirements; then, in order toensure fairness between video streams, MAC layer scheduler allocates radio resources inaccordance with the proportional fair (PF) algorithm under constraints of the rate requirements. Viasimulation, we can see that compared to EXP scheduling algorithm, the PSNR is highly improved,and PLR is less. Thus, the proposed APP-MAC cross-layer resource allocation algorithm canefficiently improve the QoE of end users. In the end, the paper discusses the relay-based two-hop multi-user resource schedulingalgorithm for video stream in OFDMA network. The scheduling priority jointly considers the packetdelay, the importance of different frames, packet loss rate (PLR) and the instantaneous downlinkrate for both direct-link users and relay-link users. The experiment results show that the proposedalgorithm performs better in PLR, average packet delay values and PSNR performance than theoriginal algorithm. Cooperative diversity greatly improves the video quality of the users.