Stream Allocation in MIMO Ad Hoc Networks

We investigate the problem of scheduling flows for fair stream allocation in ad hoc networks utilizing multiple antennas at the transmitter and receiver side known as a
Multiple Input Multiple Output (MIMO) antenna technology. Our main contributions include:

i) The concept of stream allocation to flows based on their traffic demands or class.
ii) Achieving the proportional fairness of the stream allocation in the minimum possible
schedule length.

We first formulate demand-based fair stream allocation as an integer linear programming (ILP) problem whose solution is a schedule that is guaranteed to be contention-free. We then solve this ILP in conjunction with binary search to find a minimum-length contention-free schedule that achieves fairness goals. We also show that an implementation of our algorithm for a number of sample topologies in fact yields minimum length schedules that achieve fairness goals.

This paper was published in IEEE Broadnets 2007 and won The Wireless Symposium Best Paper Award. For a copy of the paper click here.

We developed a collision free MAC protocol for wireless ad-hoc networks with multiple input multiple output (MIMO) links. The proposed MAC protocol provides proportional service differentiation to various classes of traffic based on their respective bandwidth demands. It exploits the spatial multiplexing and interference suppression capability of MIMO links in order to activate multiple links in the same collision domain. Simulation results show that the proposed MAC protocol achieves strict fairness in maintaining the proportional service differentiation among contending links. Then we introduce the concept of proportional fairness deviation which can be used as a tuning knob for assigning the leftover bandwidth to different traffic classes in proportion to their differentiation parameters. This tuning knob will adjust the quality of service assigned to users in a particular traffic class for a specific cost.

The paper was published in Proceedings of 16th International Conference on Computer Communications and Networks, ICCCN, 13-16 Aug. 2007. For a copy of the paper please click here.