Abstract
Congestion control in wireless networks is strongly dependent on the dynamics and instability of wireless links. Therefore, it is very difficult to accurately evaluate the characteristics of the wireless links. It is known that TCP experiences serious performance degradation problems in wireless networks. Moreover, congestion control mechanisms that rely on network interaction and network parameters, such as XCP and RCP, do not evaluate accurately the capacity and available link bandwidth in wireless networks. In this paper we propose new explicit flow control protocols for wireless mesh networks, based on XCP and RCP. We name these protocols XCP-Winf and RCP-Winf. They rely on the MAC layer information gathered by a new method to accurately estimate the available bandwidth and the path capacity over a wireless network path. The estimation is performed in real time and without the need to intrusively inject packets in the network. These new congestion control mechanisms are evaluated in different scenarios in wireless mesh and ad hoc networks and compared against several new approaches for wireless congestion control. It is shown that both XCP-Winf and RCP-Winf outperform the evaluated approaches, showing its stable behavior and better channel utilization.
Highlights
Reliable transport protocols such as transmission control protocol (TCP) were developed to perform well in traditional wired networks where packet losses occur mostly because of congestion [1]
The two scenarios consist of a 1000 m × 1000 m area, divided into three distinct parts: an area of 250 m × 250 m where there are two mobile node sources, one with TCP and the other with XCP-Winf or rate control protocol (RCP)-Winf; a middle area of 500 m × 500 m with two mobile nodes with the rt-Winf mechanism activated; another area of 250 m × 250 m for the mobile nodes sinks
In this paper we presented a study that demonstrates that using MAC layer information in congestion control, through a cross layer communication process, can be an important factor of network performance improvement
Summary
Reliable transport protocols such as TCP were developed to perform well in traditional wired networks where packet losses occur mostly because of congestion [1]. They aim to achieve faster convergence, smaller packet loss rate, high link utilization, and better fairness between flows Examples of these congestion control mechanisms that rely on network interaction are the explicit control protocol (XCP) [3] and the rate control protocol (RCP) [4]. The support of explicit congestion control and network interaction is expected to lead to a more efficient congestion control in shared medium systems, such as wireless mesh and ad hoc networks, we have shown in [5] that this is not the case, since they are incapable of predicting effectively capacity in wireless networks, and that they are not efficient and fair This is due to the fact that the available capacity at a wireless link depends on the link rates at the neighboring edges.
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