Distance-and-Rate Dependent RTS/CTS Reservation in Wireless LAN for Enhancing Spatial Reuse

With the emergence of functional wireless terminals, increased network capacity is needed for wireless LANs. Considering the limited available frequency channels for wireless LAN, improving spatial channel reuse performance of MAC protocol is a key requirement for this purpose. In this paper, we present a novel RTS/CTS reservation scheme for CSMA/CA which improves spatial reuse by taking account for inter-node distance in the network. The main feature of the proposed scheme is that it adaptively change range of NAV (Network Allocation Vector) depending on the distance between a source node and a destination node. The range of NAV is also changed on the current required SINR (Signal and Interference Noise Ratio) which is determined by the current transmission rate, thus this scheme can be used for multirate data transmission. Performance evaluation using a synchronous frame based media access model shows the proposed scheme improves bandwidth efficiency by about 30% at maximum compared with existing CSMA/CA with RTS/CTS.