Wireless networks are mostly architected on the principles of modularity and layering. Emerging software radio platforms are beginning to blur the layer-boundaries, exporting PHY layer information to the MAC. Protocol designers are beginning to harness PHY layer functionalities, and as a consequence, understanding the network-wide implications of PHY-aware protocols. The PHY layer community, in turn, is beginning to receive feedback on practical constraints from the networking systems community. Such a holistic approach is enabling researchers to question long-standing assumptions, conceive disruptive ideas, and test their feasibility on actual systems.
In our research, we have been performing such exercises. For instance, while traditional MAC protocols perform contention resolution in the time domain (also called backoff), we find that OFDM based systems can migrate this process into the frequency domain, thereby eliminating a long-standing source of inefficiency. In another example, we show that collision detection (implemented in wired Ethernets) may be feasible even in wireless networks. Beyond wireless capacity, we find that PHY information not only encode bits but also contains rich information about the ambience and hence can be exploited as a sensor — benefitting pervasive mobile computing applications. We exemplify this research vision by demonstrating how ambient PHY sensor can lead to precise indoor localization. We will close not only with challenges we are struggling with, but will also look into what may lie ahead under the broader umbrella of PHY layer enabled systems.
Souvik Sen is a final year PhD candidate of CS at Duke University working under the supervision of Prof. Romit Roy Choudhury. His research interests are in wireless networking mainly at the MAC/PHY layer, and in mobile computing at the application layer. His research has been published in conferences like ACM MOBICOM, MOBISYS, USENIX NSDI, IEEE ICNP and ACM HOTNETS. His work on reducing wireless contention overhead “Listen before you talk but on the frequency domain” won him the 1st prize at ACM MOBICOM Student Research Competition 2010. Recently he won the “Outstanding Preliminary Examination Talk” at Duke University. In the summer of 2010, he was a research intern at Microsoft Research.