Restructuring Wireless Systems using PHY Layer Information

Wireless and mobile systems play an increasingly important role in our lives. Fueled by an array of innovative services and applications, mobile data traffic is surging rapidly. Traditionally, wireless traffic growth is met by acquiring new spectrum. However, wireless spectrum demand is soon going to surpass it's availability. Thus, there is an urgent need for major innovations in wireless network architecture, so that our spectrum utilization can achieve its full potential. Motivated by this problem, we explore an alternative design of physical layer aware wireless systems.

Typical approaches towards improving wireless performance is confined within the physical (PHY) or link layers of the networking stack, providing only partial so- lutions. In this thesis, we advocate to consider the entire network architecture holis- tically. We show how rich PHY layer information can be utilized to address existing challenges in wireless networking - contention resolution, rate control, interference management, etc. We design, implement, and experimentally evaluate protocols to understand network-wide implications of PHY-aware systems. We also pursue the observation that PHY layer not only encode bits but also contain rich information about the ambience, and hence can be viewed as a sensor. This sensing informa- tion can be further coupled with other phone sensors, thereby benefitting pervasive mobile services and applications. We demonstrate how this synergy can contribute towards designing precise indoor localization systems, an important building block for next generation mobile applications.