Enhanced Spatial Reuse in Multi-Cell WLANs

When IEEE 802.11 access points (APs) share the same channel in a multi-cell WLAN, their downlink transmissions can interfere. Typically, an AP whose scheduled transmission to some user is blocked by another cell will apply the CSMA/CA back-off algorithm and continue to make reattempts to the same user. Through analytical models and simulations, we demonstrate that significant capacity gains can be attained by choosing an alternative destination for the reattempt. Results demonstrate that a simple random choice of alternative destination brings almost the same gain as a more sophisticated algorithm that seeks to maximize spatial reuse.