Optimal One-Shot Stream Scheduling for MIMO Links in a Single Collision Domain

This paper considers the problem of scheduling the maximum number of streams in a single time slot under the MIMO degrees of freedom (DOF) model, when all links are in a single collision domain. In the DOF model, nodes can use degrees of freedom provided by their antenna arrays to multiplex multiple streams on a single link and/or cancel interference between concurrently transmitting links. Given a set of links with data to transmit that are free of primary interference, we provide optimal constructions for both the case where only spatial reuse (from interference cancellation) is allowed and the case where both spatial reuse and spatial multiplexing can be done simultaneously. Our analysis allows deriving clean throughput performance trends when the number of available DOFs is arbitrarily increased. These trends show that combining spatial multiplexing with spatial reuse can arbitrarily increase throughput compared to spatial reuse only, and that close to two-fold throughput increases can be achieved compared to spatial multiplexing only. Finally, we show how the approach can be extended to deal with primary interference and optimally solve the one-shot stream scheduling problem for an arbitrary set of MIMO links in a single collision domain.