Design of Coordinator to Eliminate Redundant Local Retransmission in Wireless Networks

Owing to limited bandwidth, high bit error rate, and bursty error in the wireless environment, the performance of the transmission control protocol (TCP) degrades greatly in wireless networks. Up to now, many researchers have contributed greatly to the wireless TCP field. However, in most of their works, the wireless TCP module usually works in the TCP layer and has no idea of the actual time of the packet transmission, which is determined by the Scheduler in the media access control (MAC) layer, and this will bring the inaccuracy to the local retransmission timeout and induce the redundant local retransmission. In this article, a coordinator is introduced into the base-station (BS), which can provide efficient cooperation between the TCP module and the scheduler module. On the bais of the performance analysis and simulation results, the proposed method is shown to eliminate redundant local retransmission, increase throughput, and improve TCP-level fairness in wireless networks. Moreover, this scheme is orthogonal to those existing wireless TCP schemes, thus it can give great compatibility to the current networks, and further enhance the performance of TCP under the condition that the performance improvement benefiting from the existing approaches will not be affected.