Beneficial Cooperation Ratio in Multi-hop Wireless Ad Hoc Networks

In this paper, we study the differences of applying cooperation to fully-connected and multi-hop wireless networks, and find out that both the enlarged interference area and link density play a pivotal role in making the beneficial cooperation decision in a multi-hop network. Through characterizing effects of the enlarged interference area and link density on the overall network performance, a beneficial cooperation opportunity can be identified. By employing a randomized scheduling scheme and deriving the interference-free probability of any two links, the expected numbers of concurrent direct and cooperative transmissions can be obtained, where the ratio of these two numbers is defined as the beneficial cooperation ratio. Such a ratio translates the reduced spatial reuse to a requirement of the cooperation gain and provides a guideline for enabling beneficial cooperation on a single-link basis. Finally, the analytical and simulation results demonstrate that the beneficial cooperation criterion for a multi-hop network derived in this paper is more accurate than that in [1].