Research
Low-Power Wide Area Networks (LPWAN):
As a key technology driving the Internet-of-Things (IoT), Low-Power Wide-Area Networks (LPWANs) are evolving to overcome the range limits and scalability challenges in traditional wireless sensor networks. With the support from NSF and through collaboration with Microsoft Research, we have developed a highly scalable LPWAN architecture – called SNOW (Sensor Network Over White Spaces)- by designing sensor networks to operate over the TV white spaces. White spaces refer to the allocated but locally unused TV channels, and can be used by unlicensed devices, according to the FCC in the US. Compared to the existing LPWAN technologies, SNOW offers much higher scalability and energy efficiency and takes the advantages of freely available TV white spaces.
Reverse and Replace Decoding (RnR):
Interference between concurrent transmissions causes severe performance degradation in a wireless network. RnR addresses interference cancellation to enable simultaneous packet receptions at a node with a single radio in Wireless Sensor Networks (WSN). Interference cancellation is particularly important for WSN as most of its applications rely on converge-cast where all the traffic in the network is delivered to a base station leading to a lot of packet collisions. Existing solutions for collision recovery make simplified assumptions such as the availability of one of the collided packets, repeated collisions of the same packets, and the ability to identify the collided packets before recovering them which do not hold for WSNs and most wireless networks RnR entails a physical-link layer design to exploit the raw samples of the colliding signals. It does not rely on the assumptions made in existing work, and can recover all packets from a single collision.
Cellular System for Emergency and Disaster Relief:
The system utilizes Unmanned Aerial Vehicles (UAV) to form a wireless mesh network in the sky to provide cellular access so that users with standard mobile phone will be able communicate. This system will be critical after occurrences such as tsunamis, hurricanes and earthquakes where ground based communications infrastructure are destroyed.