MAC-PHY Cross-layer Techniques for Simultaneous Multiuser Communication in Wireless Networks

Layering in wireless networks provide clear abstractions to how various resources are managed for a particular communication link. However, the unpredictability of the wireless channel presents great challenge to these clear abstractions. Often, optimizations in these layers are not transparent to others. This creates a necessity to violate the modular approach and share crosslayer information to modify each layer\u27s functionalities, which eventually improves the overall performance of the network. In this thesis, novel MAC-PHY crosslayer protocols have been designed, implemented and evaluated. These protocols provide unprecedented gain in various aspects of a wireless network, by facilitating simultaneous multiuser communication. By harnessing the untapped potential of the various signal processing subsystems in the physical layer, these protocols are able to increase network throughput, make certain group communications faster and enable covert communication. Using reconfigurable hardware to expose physical layer information, improvement is achieved in higher layers. Furthermore, it is also important to modify the physical layer based on the feedback from higher layers. The two-way handshaking changes the conventional modular approach and allows implementation of simultaneous communication in wireless domain. To make the crosslayer techniques practical, this thesis presents clear implementation steps to embed these concepts as an extension to common wireless network protocols and evaluate those using practical experiments and radio measurements. Through these techniques we are able to show practical benefits from a mutable radio and a crosslayer approach to protocol design for next generation, high bandwidth wireless networks