Efficient MAC for distributed multiuser MIMO systems

A distributed multiuser MIMO system consists of several access points which are connected to coordinating servers and operate as a large multi-antenna access point. Thanks to joint decoding and precoding, all transmitted signal power is useful, rather than “interference”. The system has the potential to support constant rates as the number of clients increases, thus offering a tremendous bandwidth boost. Despite the high gains and potential applicability to real world setups like enterprise networks, this approach is regarded today mostly as a theoretical solution because of some serious implementation difficulties. Motivated by our recent success in addressing synchronization issues in a real distributed multiuser MIMO testbed that we have developed, in this work we move one step further and design an efficient MAC scheme for such a system. First, we study and design optimal as well as practical user selection and scheduling schemes. Second, we investigate coding methods to realize the achievable rates at higher layers, and pay particular attention to recent rateless codes advancements. Last, we propose a specific MAC super-frame, and discuss how to make our system backward compatible with 802.11ac.