Principal Investigator Eytan Modiano
Increasingly we have come to depend on wireless networks for internet access. Unfortunately, existing wireless networks are almost exclusively confined to single hop access, as provided by cellular telephony or wireless LANs. Multi-hop wireless networks can be deployed; however, current protocols typically result in extremely poor performance for even moderate sized networks. Our research in the area of wireless networks attempts to bridge the gap between wireless networks and the wired internet, by addressing issues in the control and management of wireless networks, including mobile ad hoc networks, sensor networks, and wireless mesh networks. The goal is to develop develop architectures, protocols, and control algorithms for providing efficient and reliable wireless networking.
Projects include fundamental aspects of network control, robust wireless network design, as well as the design of practical practical network control algorithms for routing, scheduling and flow control.
Effective Control of Wireless Networks -- Wireless Mesh Networks (WMNs) have emerged as a solution for providing last-mile Internet access. By exploiting advanced communication technologies such as adaptive modulation and coding, MIMO, OFDM, and Software Radio, WMNs can achieve access rates that are comparable to those achieved by wired access technologies. However, hindering their success is our relative lack of understanding of how to effectively control wireless networks; especially in the context of advanced physical layer technologies, realistic models for channel interference, and distributed operation. The goal of this project is to develop effective and practical network control algorithms that make efficient use of wireless resources through joint topology adaptation, network layer routing, MAC layer scheduling, and physical layer power, channel, and rate control.
Toward Reducing Control Overhead in Wireless Networks -- Network control mechanisms, such as scheduling, routing, and flow control, ensure effective data transport in a communication network, but also require the exchange of network state information, such as channel conditions and queue-length information, which amounts to “control overhead”. The project investigates the tradeoffs between the rate of sending such control information, and the ability to effectively control the network in terms of performance metrics such as throughput, stability, delay and network utility. The project takes a two-pronged approach: First, a rate-distortion framework is being developed for understanding the impact of degraded network state information on network performance. Second, mechanisms are being developed for reducing the amount of control overhead and the impact of these mechanisms on network performance is being investigated. The project develops a fundamental understanding of the requirements for protocol overhead, which will lead to more efficient network control policies, with reduced overheads.
Protection and restoration in wireless mesh networks -- Most previous work on routing in ad hoc networks has focused almost entirely on the problem of route discovery. Little, if any, attention has been paid to the problem of reliable communications in a mobile network. In a network this is often accomplished by providing "backup" routes. However, recovery using backup routes in ad hoc networks is very different from a static fiber networks due to the high degree of mobility that results in rapid topology changes. This project will develop efficient recovery mechanisms in a mobile ad hoc environment.