Cooperative Spatial Reuse with Transmit Beamforming in Multi-rate Wireless Networks

We present a cooperative spatial reuse (CSR) scheme as a cooperative extension of the current TDMA- based MAC to enable spatial reuse in multi-rate wireless networks. We model spatial reuse as a cooperation problem on utilizing the time slots obtained from the TDMA-based MAC. In CSR, there are two operation modes. One is TDMA mode while the other is spatial reuse mode in which links transmit simultaneously. Links contribute their own time slots to form a cooperative group to do spatial reuse. Each link joins the group only if it can benefit in capacity or energy efficiency. Otherwise, the link will leave spatial reuse mode and switch back to TDMA. In this work, we focus on the transmit beamforming techniques to enable CSR by interference cancellation on MISO (Multiple Input Single Output) links. We compare the CSR scheme using zero- forcing (ZF) transmit beamforming, namely ZF-CSR, to the TDMA-based MAC using maximum ratio combining (MRC) transmit beamforming, namely MRC-TDMA. The numerical results of a simulated two 2 × 1 MISO links scenario show the great potential of CSR to substantially increase the capacity and energy efficiency.