Research:

Cognitive Radios, Variable Channel-Width Systems

We are working on two fronts. First, on a system (hardware + software) capable of operating in the TV bands (700 MHz of the spectrum). The goal is to efficiently utilize the available spectrum without interfering with licensed users. Second, we are exploring a more powerful WLAN architecture with variable channel widths in the ISM bands, in contrast to existing systems based on IEEE 802.11 that use channels of fixed width. There are several benefits of this new architecture, including better load balancing in enterprise WLANs. More details on this project can be found here.

Network Management

With the increasing complexity of enterprise networks, there is a pressing need for efficient approaches to detect, localize, diagnose and repair faults in the network. I have worked on several aspects of network management as part of a bigger project, called NetHealth. Sherlock uses dependency analysis to localize faults that impact end-users, DAIR helps IT administrators locate regions of poor WLAN coverage and performance, and WiFiProfiler enables users to collaborately diagnose Wi-Fi problems.

Mesh Networks

I have worked on networking issues in layer 2 and layer 3 (unicast + multicast) in wireless mesh networks. The details of this project are available on our group's Mesh Networking page.

Fun Stuff, Clean Slate Wireless Systems

Wi-Fi is designed as a convenient replacement for the wire, and its design mostly attempts to mimic the behavior of the Ethernet. For example, a Wi-Fi card needs to associate to an Access Point (AP) before it can send data packets, which is similar to the action to plugging the Ethernet cable in the wall. Furthermore, Wi-Fi restricts a card to associate to at most one AP. In my opinion, the wireless medium has a number of powerful properties and wireless networks should be treated differently from traditional wired networks. I have built some systems that try to break away from these constraints in Wi-Fi networks as part of VirtualWiFi and WiFiAds projects. I am also exploring fun hacks in cellular networks, such as in Cell2Notify.