Congestion Avoidance Control Research Articles

Wireless Sensor Networks Congestion Control Algorithm Based on Fusion Judgment

With the rapid development of sensor network, the network scale is expanding and nodes are deployed in a large amount. The dynamic change of wireless link quality and sudden traffic of sensor network are easy to cause network congestion, packet loss and waste of energy. In this paper, a congestion avoidance control algorithm (FJCA) for wireless sensor networks was proposed based on the fusion judgment method, and factors such as the distance from node to base station, the residual energy of node and the length of cache queue were considered. And compared it with TADR and MDD algorithms, the results show that the algorithm has higher energy efficiency and balance of nodes, which can improve network throughput more effectively, extended the life cycle of wireless sensor networks, and improve the service quality of network.

HWN* Mobility Management Considering QoS, Optimisation and Cross Layer Issues

In this paper, we address mobility management for 4th generation heterogeneous networks from a quality of service (QoS), optimisation and cross layer design perspective. Users are classified as high profile, normal profile and low profile according to their differentiated service requirements. Congestion avoidance control and adaptive handover mechanisms are implemented for efficient cooperation within the mobile heterogeneous network environment consisting of a TDMA network, ad hoc network and relay nodes. A previous proposed routing algorithm is also revised to include mobility management.

Improving TCP performance in integrated wireless communications networks

Many analytical and simulation-based studies of TCP performance in wireless environments assume an error-free and congestion-free reverse channel that has the same capacity as the forward channel. Such an assumption does not hold in many real-world scenarios, particularly in the hybrid networks consisting of various wireless LAN (WLAN) and cellular technologies. In this paper, we first study, through extensive simulations, the performance characteristics of four representative TCP schemes, namely TCP New Reno, SACK, Veno, and Westwood, under the network conditions of asymmetric end-to-end link capacities, correlated wireless errors, and link congestion in both forward and reverse directions. We then propose a new TCP scheme, called TCP New Jersey, which is capable of distinguishing wireless packet losses from congestion packet losses, and reacting accordingly. TCP New Jersey consists of two key components, the timestamp-based available bandwidth estimation (TABE) algorithm and the congestion warning (CW) router configuration. TABE is a TCP-sender-side algorithm that continuously estimates the bandwidth available to the connection and guides the sender to adjust its transmission rate when the network becomes congested. TABE is immune to the ACK drops as well as ACK compression. CW is a configuration of network routers such that routers alert end stations by marking all packets when there is a sign of an incipient congestion. The marking of packets by the CW-configured routers helps the sender of the TCP connection to effectively differentiate packet losses caused by network congestion from those caused by wireless link errors. Our simulation results show that TCP New Jersey is able to accurately estimate the available bandwidth of the bottleneck link of an end-to-end path; and the TABE estimator is immune to link asymmetry, bi-directional congestion, and the relative position of the bottleneck link in the multi-hop end-to-end path. The proactive congestion avoidance control mechanism proposed in our scheme minimizes the network congestion, reduces the network volatility, and stabilizes the queue lengths while achieving more throughput than other TCP schemes.