On False Blocking in RTS/CTS-Based Multihop Wireless Networks

The request-to-send/clear-to-send (RTS/CTS) mechanism is widely used in wireless networks in order to avoid packet collisions and, thus, achieve high network throughput. In multihop settings, however, current implementations of the RTS/CTS mechanism may lead to interdependencies that unnecessarily prohibit nodes from transmitting over long periods of time. We refer to this problem as "false blocking." In this paper, we describe and analyze the false blocking problem in detail. We show that false blocking can lead to a significant performance degradation in a variety of topologies and, possibly, to network-wide congestion as well. We propose a backward-compatible solution to the false blocking problem, called the RTS validation. We model and analyze the performance of RTS validation under general traffic and topology settings and show that it achieves a considerable reduction in the probability of false blocking. Furthermore, we carry out extensive simulations that validate our analysis and show that the RTS validation stabilizes the throughput at high load and increases its peak value, sometimes by as much as 50%