oa Interference-aware protocol design in wireless networks

Wireless networking is enabling a new class of applications providing users with access to information and communication anytime and anywhere. The success of these applications and services, accessible through smart phones and other wireless devices, is placing tremendous pressure on the limited wireless bandwidth. To sustain this growth, it is critical to develop protocols that can efficiently manage the available bandwidth.

One of the major complications in developing these wireless protocols is the complex effect of interference between different users, which often plays a defining role on the overall performance of wireless networks. Thus, the goal of this project is to characterize the interference behavior and use it to develop a new generation of protocols that focus on minimizing destructive interference.

We focus on Carrier Sense Multiple Access (CSMA), the most commonly used algorithm in wireless networks at the core of widespread standards such as IEEE 802.11 (WiFi). These protocols are unable to effectively arbitrate the medium in multi-hop wireless networks, causing destructive interactions such as hidden and exposed terminals, leading to collisions, poor performance and unfairness. This project first characterizes the impact of interference in detail, showing that there are only a few modes of interference that account for the different interactions that occur when multiple users compete for use of the medium.

We then use this insight to develop novel protocols using two main strategies: (1) remove destructive interference whenever possible; and (2) find alternative routes around destructive interference areas when removing interference is not an option. For the first part our methodology controls transceiver parameters like transmit power, receiver threshold and receiver sensitivity to convert the destructive interactions into constructive ones. Our results show that this technique reduces the overall power consumed in a network allowing for better channel reuse and hence efficient capacity usage. For the latter part, we are designing a routing protocol that routes traffic around areas of potentially high interference. A comparison of our protocol with existing shortest-path routing protocol shows that our metric substantially improves the performance and efficiency of the network.