Improving spatial reuse of IEEE 802.11 based ad hoc networks

In this paper, we evaluate and suggest methods to improve the performance of IEEE 802.11 based ad hoc networks from the perspective of spatial reuse. Since 802.11 employs virtual carrier sensing to reserve the medium prior to a packet transmission, the relative size of the spatial region it reserves for the impending traffic significantly affects the overall network performance. We show that the space reserved by 802.11 for a successful transmission is far from optimal and depending on the one hop distances between the sender and the receiver. We study three scenarios with very different spatial reuse characteristics. We also introduce a new quantitative measure, the spatial reuse index, to evaluate the efficiency of the medium reservation accomplished by 802.11 virtual carrier sensing. We also propose an improved virtual carrier sensing mechanism for wireless LAN scenarios and using analysis and simulation results, show that it can significantly increase the spatial reuse and network throughput.