Analyzing delay limits of high-speed wireless ad hoc networks based on IEEE 802.11n

Recent advances in high-speed wireless LANs with physical layer (PHY) rates reaching 600Mbps make them ideal for multimedia applications. It has been shown that efficiency at medium access control (MAC) layer decreases with increasing the PHY rate. To achieve high efficiency, few researches have tried to use aggregation in which few packets are concatenated into a larger frame. The resultant frame is sent at once in order to reduce the media access protocol overhead. Unfortunately larger frames increase delays. Since demand for real-time data communication and delay-sensitive applications have become more critical, especially for high-speed networks, a thorough delay analysis is required to examine the effect of aggregation on delay in high-speed networks. In this paper, we propose an analytical model for examining packet delay in IEEE 802.11n networks in the saturation mode. To the best of our knowledge, this is the first work which focuses on packet delay analysis in the presence of aggregation. Analysis and simulation results show that packet delay increases in larger aggregation sizes, and IEEE 802.11n performs poorly in high rates in terms of packet delay. Moreover, based on two new metrics that we propose in the paper, it is shown that aggregation loses its effectiveness in higher rates.