Research On Cross-layer Design Algorithms Of Wireless TCP And Resource Scheduling

With the rapid development of next-generation wireless networks (NGWN) and the explosive growth of multimedia applications, the traditional design of layered protocol stack exhibits quite a few disadvantages. Targeting to the maximization of network performance, the cross-layer design approach has been the hot research topic of telecommunication sector. With reference to the application of NGWN, this dissertation focuses on the cross-layer design of TCP performance optimization and multiuser OFDMA system resource scheduling algorithm based on the cross-layer awareness under wireless network environment. The purpose is to enhance their adaptability to the wireless network through the cross-layer coordination of different layer parameters within TCP/IP protocol stack.First of all, an overview is given of related key technologies of NGWN together with the idea and the-state-of-the-art of the cross-layer design. Following the above discussion, to tackle the problem of performance degradation of the current TCP congestion control algorithm under the wireless environment, an improved wireless TCP algorithm is proposed using the cross-layer mechanism based on explicit congestion notification (ECN). The simulation results have shown that the proposed cross-layer mechanism can improve the performance of network throughput and the efficiency of network resource utilization.Furthermore the dissertation makes study on the resource scheduling of NGWN, and an improved cross-layer design algorithm is proposed for single-cell OFDMA system resource scheduling. The algorithm allocates the resource taking into account both the physical channel state information and parameters of other layers reflecting the system fairness and QoS requirements. The simulation results have shown that, in comparison to the existing algorithms, the proposed algorithm enhances the fairness of scheduling mechanisms and spectrum efficiency of wireless systems.