On Improving Wireless Channel Utilization: A Collision Tolerance-Based Approach.

Packet corruption caused by collision is a critical problem that hurts the performance of wireless networks. Conventional medium access control (MAC) protocols resort to collision avoidance to maintain acceptable efficiency of channel utilization. According to our investigation and observation, however, collision avoidance comes at the cost of miscellaneous overhead, which oppositely hurts channel utilization, not to mention the poor resiliency and performance of those protocols in face of dense networks or intensive traffic. Discovering the ability to tolerate collisions at the physical layer implementations of wireless networks, we in this paper propose $Coco$ , a protocol that advocates simultaneous accesses from multiple senders to a shared channel, i.e., optimistically allowing collisions instead of simply avoiding them. With a simple but effective design, $Coco$ addresses the key challenges in achieving collision tolerance, such as precise sender alignment and the control of transmission concurrency. We implement $Coco$ in 802.15.4 networks and evaluate its performance through extensive experiments with 21 TelosB nodes. The results demonstrate that $Coco$ is light-weight and enhances channel utilization by at least $20\\,\\text{percent}$ in general cases, compared with state-of-the-arts protocols.