Opportunistic and Cooperative Spatial Multiplexing in MIMO Ad Hoc Networks

With the fast progress of multiple-input-multiple-output (MIMO) technology and its growing applications in networks, it is important to develop techniques to enable more efficient MIMO network communications. However, it is very challenging to coordinate node transmissions in a MIMO-based ad hoc network. In this work, we propose schemes that take advantage of the meshed topology of ad hoc networks to fully exploit the multiuser diversity and spatial diversity in order to maximize the data rate of the network while supporting different transmission priorities, reducing transmission delay, and ensuring fair transmissions among nodes. We formulate a concrete physical model and present cross-layer centralized and distributed scheduling algorithms that exploit physical-layer channel information to opportunistically schedule cooperative spatial multiplexed transmissions between nodes. We also propose a new MAC scheme to support our distributed algorithm. The performance of our algorithms are studied through extensive simulations, and the results demonstrate that our algorithms are very effective and can significantly increase the network throughput while reducing the transmission delay.