Client Beamforming for Rate Scalability of MU-MIMO Networks

In a multi-user MIMO (MU-MIMO) network, an AP with multiple antennas can simultaneously serve multiple clients to increase the achievable rates. To realize such rate improvement, the MU-MIMO AP can leverage beamforming techniques such as zero-forcing beamforming (ZFBF) to eliminate the intra-cell interference between simultaneously served clients. However, current MU-MIMO networks suffer from two fundamental problems that limit the rate scalability to the number of served clients.

We study two client-beamforming-based solutions.




Our prototyping of MACCO and CoaCa is on the WARP platform from Mango Wireless, based on the framework. In WARPLab, through gigabytes Ethernet cables, multiple WARP boards configured as APs or clients are interconnected to and controlled by a central computer that runs MATLAB. Since the baseband processing occurs in MATLAB, we cannot implement the 802.11ac MAC satisfying the timing constraint. Therefore we move the channel sounding processes of MACCO and CoaCa into emulation, including client polling, beamformed channel (virtual channel) reporting and overhearing.

As channel sounding in emulated, our MACCO and CoaCa software supports both trace-based simulation and WARPLab-based experiments.

Click here to download the source code.

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