Increasing Spatial Multiplexing Gain in Future Multi-AP WiFi Systems via Joint Transmission

There has recently been a growing interest in multi-AP coordination technologies for the next generation of WiFi systems. Of the several flavors under consideration, the most sophisticated is joint transmission (JT), which can potentially achieve multiplicative gains in network throughput proportional to the number of participating APs via concurrent distributed MU-MIMO. In this article, we provide a survey of the practical challenges envisioned in realizing gains for JT and the methods proposed to address them in the context of 802.11. We also briefly review other multi-AP schemes that involve coordination in the spatial domain, and contrast their requirements and achievable gains vs. JT.