BCTMA (Bi-directional Cut-Through Medium Access) Protocol for 802.11-Based Multi-hop Wireless Networks

Abstract

In DCF of 802.11-based multi-hop wireless networks, a channel access sequence of 4-way handshake with RTS-CTS-DATA-ACK is used to forward a single packet. For multi-hop packet forwarding, multiple channel accesses with this 4-way handshake are required, and this might entail multiple collisions, which, in turn, results in poor end-to-end performance. To eliminate the overhead of these multiple channel accesses and, as a result, to reduce the possible number of collisions, the DCMA (Data-driven Cut-through Medium Access) protocol has been proposed[5]. We name the scheme used in the DCMA protocol the forward cut-through scheme. In this paper, we propose BCTMA (Bi-directional Cut-Through Medium Access)protocol for high performance 802.11-based multi-hop wireless networks by combining both forward and backward cut-through schemes. We have implemented BCTMAprotocol in ns-2[9]. We conducted a comprehensive simulation to study the performance improvements. The simulation results indicate that the performance is significantly improved and the number of dropped packets due to collisions can be significantly reduced as much as a half.

This work was supported by grant No. R01-2002-000-10934-0 (2005) from the Basic Research Program of the Korea Science & Engineering Foundation and by the Research Grant of KwangWoon University in 2003.