Embracing Interference in Wireless Systems. Shyamnath Gollakota
- Описание
- Фрагмент
The wireless medium is a shared resource. If nearby devices transmit at the <br/> same time, their signals interfere, resulting in a collision. In traditional <br/> networks, collisions cause the loss of the transmitted information. For this <br/> reason, wireless networks have been designed with the assumption that <br/> interference is intrinsically harmful and must be avoided. <br/> <br/> <br/> This book, a revised version of the author's award-winning Ph.D. <br/> dissertation, takes an alternate approach: Instead of viewing interference <br/> as an inherently counterproductive phenomenon that should to be avoided, we <br/> design practical systems that transform interference into a harmless, and <br/> even a beneficial phenomenon. To achieve this goal, we consider how wireless <br/> signals interact when they interfere, and use this understanding in our <br/> system designs. Specifically, when interference occurs, the signals get <br/> mixed on the wireless medium. By understanding the parameters of this <br/> mixing, we can invert the mixing and decode the interfered packets; thus, <br/> making interference harmless. Furthermore, we can control this mixing <br/> process to create strategic interference that allow decodability at a <br/> particular receiver of interest, but prevent decodability at unintended <br/> receivers and adversaries. Hence, we can transform interference into a <br/> beneficial phenomenon that provides security. <br/> <br/> <br/> Building on this approach, we make four main contributions: We present the <br/> first WiFi receiver that can successfully reconstruct the transmitted <br/> information in the presence of packet collisions. Next, we introduce a WiFi <br/> receiver design that can decode in the presence of high-power <br/> cross-technology interference from devices like baby monitors, cordless <br/> phones, microwave ovens, or even unknown technologies. We then show how we <br/> can harness interference to improve security. In particular, we develop the <br/> first system that secures an insecure medical implant without any <br/> modification to the implant itself. Finally, we present a solution that <br/> establishes secure connections between any two WiFi devices, without having <br/> users enter passwords or use pre-shared secret keys.
