Multihop transmission is increasingly being incorporated into modern wireless communication networks. These networks are central to our nation's future communications and monitoring infrastructures. The basic motivation for multihop is that transmissions occur over shorter distances -- and therefore with higher received signal strength -- via many intermediate nodes rather than over longer distances -- and therefore with lower received signal strength -- between the source and destination of the information. However, multihop transmission involves complex interactions among channel coding at the physical layer, distributed channel access at the link layer, and multihop routing at the network layer. These techniques have been studied largely in isolation by different communities, whereas this project focuses on their interaction, especially in delay-constrained scenarios.
This research involves models for general wireless multihop networks, and develops tradeoffs for transmission along an individual routes of up to M + 1 nodes. Transmission between the end nodes can occur in a single hop, or up to M hops. Multihop transmission increases the received signal-to-noise ratio (SNR) at intermediate nodes; however, this observation does not take into account the important practical issues of power and bandwidth allocation, end-to-end delay, error propagation, or interference induced by other transmitters. Among other results, preliminary research indicates that the benefits of multihop are eroded by these issues, especially for high spectral efficiency, i.e., high data rates relative to the available bandwidth. The investigators take a comprehensive look at multihop transmission from the point of view of communication theory, mathematical networking, and networking practice, with the goal of offering solutions that will impact a major part of our society.
