【摘 要】
：
In this paper,a modified access mechanism named Constrained-send DCF (CDCF) is proposed to improve the performance of IEEE 802.11 DCF protocol.It is found that,
【机 构】
：
Tsinghua National Laboratory for Information Science and Technology,Ericsson(China)Communications Co
【基金项目】
：
Sponsored by the National Natural Science Foundation of China;the National S&T Major Project;the National Key Basic Research and Development Project
论文部分内容阅读
In this paper,a modified access mechanism named Constrained-send DCF (CDCF) is proposed to improve the performance of IEEE 802.11 DCF protocol.It is found that,in DCF,the transmission probability is higher than the reasonable value when the node number is greater than 4 under basic access scheme or than 17 under RTS/CTS scheme,and it results in serious collision.To avoid collision of high access loading,a constrained-send probability is introduced at the end of each back off procedure for the station transmitting.The performance of this mechanism is analyzed based on a 2-Dimension Markov analytical model,after that the optimum constrained-send probability is derived.Numerical results show that the CDCF mechanism has much better performance than DCF with respect to both system throughput and average packet delay.And under RTS/CTS scheme,although CDCF slightly improve the throughput performance (due to the natural good throughput performance of RTS/CTS-scheme DCF),it leads to a much better average packet delay performance compared to DCF.The CDCF keeps all the features of the IEEE 802.11 DCF protocol and is quite easy to implement.
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