Multi-channel Enhancements for IEEE 802.11-Based Multi-hop Ad-Hoc Wireless Networks

Collision avoidance is critical for the performance of contentionbased medium access mechanism such as CSMA. In this paper, the IEEE 802.11-based MAC protocol is enhanced for performance improvements in multi-hop ad-hoc wireless networks. The protocol behavior of hidden terminals in carrier sensing range[10] is important for end-to-end performance. There are several mechanisms defined in IEEE 802.11 standard such as IFS(Inter Frame Space), but we address a problem that such time interval is not long enough to avoid unnecessary collisions by the hidden terminals in carrier sensing range. We have conducted a comprehensive simulation to study performance improvement. The simulation results indicate that the performance is increased and the number of the dropped packets due to unnecessary collisions can be significantly reduced as much as a half. Keywords—Ad-hoc wireless networks, IEEE 802.11, MAC, Collision, CAI(Collision Avoidance Interval)