QoS-aware Routing Based on Bandwidth Estimation for Mobile Ad Hoc Networks (BEQR)

Routing protocols for mobile ad hoc networks (MANETs) have been explored extensively in recent years. Much of this work is targeted at finding a feasible route from a source to a destination without considering current network traffic or application requirements. Therefore, the network may easily become overloaded with too much traffic, and the application has no way to improve its performance under a given network traffic condition. While this may be acceptable for data transfer, many real-time applications require QoS support from the network. We believe that such QoS support can be achieved by either finding a route to satisfy the application requirements or offering network feedback to the application when the requirements cannot be met. We have developed a QoS-aware routing protocol called BEQR that incorporates an admission control scheme and a feedback scheme to meet the QoS requirements of real-time applications. The novel part of BEQR is the use of the approximate bandwidth estimation to react to network traffic. Our approach implements these schemes by using two bandwidth estimation methods to find the residual bandwidth available at each node to support new streams. We simulated our QoS-aware routing protocol for nodes running the IEEE 802.11 MAC. Results of our experiments show that the packet delivery ratio increases greatly, and packet delay and energy dissipation decrease significantly, while the overall end-to-end throughput is not impacted, compared with routing protocols that do not provide QoS support.

Network Architecture to Support QoS in Mobile Ad Hoc Networks

We have presented a quality of service (QoS) architecture for supporting real-time data transmission in mobile ad hoc networks (MANETs). The QoS architecture includes a QoS transport layer, QoS routing, queue management and a priority MAC protocol. Through simulations, we found that the QoS architecture reduces packet delay and greatly improves the quality of real-time video streams in MANETs.

End-to-end congestion control for best-effort Traffic (UDPC)

UDP is the standard best-effort transport layer protocol. A well-known problem with UDP is that, unlike TCP, it does not include congestion control. Thus UDP connections have no way of detecting or reacting to network congestion. This is particularly a problem in wireless networks, where a significant loss in achievable capacity occurs when using UDP transport over a congested multi-hop network running the 802.11 MAC. Considerable energy is wasted on transmitting packets that will be dropped during transmission. Since mobile ad hoc networks lack energy and bandwidth, it is necessary to use congestion control to improve the network performance while using UDP as the transport layer protocol. In this project, we explored the use of UDP with congestion control. Our simulations show that adding congestion control to best-effort traffic can greatly improve network capacity and dramatically reduce energy dissipation.

For more information about these projects, contact Lei Chen.