This article puts forward one algorithm for stream control transfer protocol (SCTP) improvement with limited receiver buffer (RBUF). As is well known, SCTP is one of the most important transfer control protocol, but most researches focus on the situations without the RBUF limit. In this study, we analyze the impact of the RBUF size on the performance. Computer simulations show that the network utility is low in reliable transfer, when the RBUF size is smaller than bandwidth delay product. By studying the transmission sequence number (TSN) transfer progress, we find that the peer receiver window (PEER_RWND), which lags behind the true receiver window (RWND), leads to the poor network utility. To improve SCTP performance with limited RBUF, the virtual receiver window (VIRTUAL_RWND) is introduced. Based on the VIRTUAL_RWND, one algorithm is proposed to increase the sending rate. Computer simulations have evaluated an excellent performance of the proposed algorithm at both ideal link without lost packet and nonideal link with lost packet.
Capacity analysis is a fundamental and essential work for evaluating the performance of cognitive wireless mesh network(CWMN)which is considered a promising option for the future network.Power control is an efficient way to avoid interference and improve capacity of wireless mesh networks.In this paper,a quantitative result of the per-node average throughput capacity of CWMN with power control is deduced for the first time,which is much helpful for understanding the limitations of CWMN.Firstly,under the large-scale channel fading model and protocol interference model,a closed-form expression for the maximum channel capacity of each node with power control is presented,under the constraint that the interference tolerated by the primary users(PUs)does not exceed a threshold.And then,with the deduced channel capacity result,the per-node average throughput capacity of CWMN is derived based on two regular topologies,i.e.square topology and triangle topology.The simulation results indicate that the capacity is effectively improved with power control,and affected by topology,tolerated interference threshold,the number of cognitive users(CUs)and primary users(PUs).
