Mobile ad hoc networks (MANETs) are highly desirable in areas/situations where base stations are unavailable or too expensive to establish. Lack of infrastructure, intermittent connectivity, and frequent changes in topology due to mobility present significant challenges in the research of MANETs. While most prior efforts were primarily focused on the networking layer, there are compelling reasons supported by recent information theory and signal processing studies which indicate that an integrated approach seeking cross-layer diversity exploitation can lead to more fruitful results. This project follows that path.
The objective of this project is to develop a framework of communication, networking, and signal processing techniques for MANETs by exploiting node cooperation at the physical, medium access, and networking layers. Three different but intertwined research directions are involved, Specifically, the first is to develop a distributive modulation theory over wireless relay channels, covering investigation of the characteristics of wireless relay channels, modulation and detection for coherent, differential and non-coherent communications for relay networks, power allocation and placement of relay nodes. The second direction is to develop bandwidth-efficient and delay-tolerant cooperative coding schemes to address several issues that are unique in coded cooperation, including bandwidth expansion caused by repetitive transmissions from relays, node asynchronism due to distributive locations of relays, and scalability (viz., the capability to degrade gracefully when some cooperating nodes that implement a distributive code fail because of fading). The third direction is to explore networking by parallel relays and develop networking protocols that take into account the realistic characteristics of radio signals and provide a flexible framework for diversity exploitation.
