User cooperative mobility for QoS improvement in ad-hoc networks

To mitigate performance anomalies due to different transmission rates and improve throughput performance in ad-hoc networks, we propose a method called user cooperative mobility in which a node, i.e., a user of an ad-hoc network, moves (changes its geometrical position) for communication. Unlike previous research regarding user cooperative mobility, it is not easy to decide to where the user should move to obtain the best result because the move may change multiple transmission rates in multiple links. Thus, we show that the best position to move to is quite different from the intuitively best position on the way to the next hop. We first evaluate throughput characteristics at every position within a movable distance from the original position of the cooperative mobility user. Then, we compare differences in throughput and direction of movement between the following three movement strategies: the best move, the intuitive move and no move. In terms of throughput improvement, which is normalized by the throughput of no move, the best move results were 40% better than those of no move and 24% better than those of the intuitive move. The direction of movement significantly differed from the intuitive move, by 92 degrees at the maximum. We conclude that cooperative user mobility with the best move is beneficial for both cooperative mobility users and ad-hoc networks.