NSF MIMO Interference Coordination Project

NeTS: Small: Practical Strategies for using MIMO to Mitigate Interference in High-Density Uncoordinated Wireless Networks

NSF Project Number: CNS–1319455



Internet traffic demand has grown remarkably in the last couple of decades, and it is predicted to increase even further in the coming years. Internet users are increasingly relying on WiFi for the last mile connectivity. This has produced a situation where, in many locations, the density of WiFi access points is extremely high. In these areas, the numerous access points and large number of users all share the scarce bandwidth of the unlicensed bands on which WiFi operates. One approach that is beginning to be considered to deal with this problem is cooperation between multiple access points (APs) serving overlapping areas. Cooperation allows more intelligent scheduling of transmissions among all competing users and also permits the use of cooperative multiple-input multiple-output (MIMO) transmission techniques, which can produce much higher aggregate throughput compared to non-cooperative techniques. This research project addressed two key technologies required to make cooperative-MIMO-based WiFi a reality: scalable and high performance cooperative MIMO techniques and scheduled WiFi. The primary goal of this project was to make major leaps forward in addressing the critical problem of limited bandwidth in dense wireless networks, with an emphasis on the use of MIMO capabilities and access point cooperation.


Accomplishments included contributions in two main areas: (1) access point (AP) cooperation with multi-input multi-output (MIMO) communications, and (2) achieving scheduled operation in wireless networks that use distributed contention.

In the area of cooperative MIMO for WiFi access points, the project participants developed a number of novel concepts and techniques that permit high performance networking while preserving computational efficiency and fairness up to a large number of users, which is necessary for the techniques to be applied in practical settings. Specific concepts and techniques developed and evaluated in this area include:

The project's research on scheduled WiFi aims to improve network performance in WiFi networks by providing controllability and predictability in channel access. Scheduled WiFi has many potential uses, among them being that it is required for the cooperative MIMO multi-AP techniques proposed in the project. Following are some of the key outcomes of the scheduled WiFi research:


The following publications were produced with partial or full support from this NSF award.

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