Toward efficient estimation of available bandwidth for IEEE 802.11-based wireless networks

Accurately measuring the available bandwidth information is critical for providing QoS (Quality of Service) assurance, especially for the bandwidth-limited 802.11-based wireless networks. However, the shared nature of wireless medium and IEEE 802.11 MAC pose great challenges for estimating the bandwidth accurately. This paper tends to tackle this issue. In particular, based on our formal definition of available bandwidth in IEEE 802.11-based wireless networks, a novel Passive Available Bandwidth Estimation (PABE) approach is proposed. In PABE, the effective link capacity is analyzed by considering the random factors in transmission like backoff and the retransmission of frame. To estimate the available channel idle time ratio (CITR), a new, lower threshold (named No Collision Sensing Range threshold, NCSR-threshold) is introduced, and the underestimation problem raised by the new threshold is compensated by the non-affect case analysis. Our approach incurs very low cost to the network without any explicit message overhead. Through extensive simulation, our data validate that our approach consistently achieves much better performance than other existing algorithms in terms of estimation accuracy.