Traffic-aware active link rate adaptation via power control for multi-hop multi-rate 802.11 networks

Many emerging wireless networks provide multi-rate facilities. How to explore the rate diversity is a new research interest. The commonly used Auto Rate Feedback (ARF) provides a flexibility of switching among the available rates. However, ARF can only passively react to the signal quality experienced at the receiver. In some occasions, we need to actively improve the signal quality in order to make the transmission rate to meet the traffic demand, even when the link length is a little large. This paper proposes a traffic-aware active link rate adaptation scheme via power control (TA-ARA) for multi-hop multi-rate 802.11 networks without degrading the serving rate of existing links. Its basic idea consists of the following points. We firstly run an ACK based information exchange to estimate the upper power bound of the link under adaptation. Then by continuously monitoring the queue length in the MAC layer, we are able to know whether the traffic demand can be met or not. If not, we try to increase the emitting power with respect to the estimated power upper-bound and switch to a higher modulation scheme. The simulations result shows that with this scheme, traffic demands can be tracked and satisfied much better than ARF.