Date Added: Oct 2009
In this paper, the authors study the capacity of Multi-User Multiple-Input Multiple-Output (MU-MIMO) downlink channels with codebook-based limited feedback using real measurement data. Several aspects of MU-MIMO channels are evaluated. Firstly, they compare the sum rate of different MU-MIMO precoding schemes in various channel conditions. Secondly, they study the effect of different codebooks on the performance of limited feedback MU-MIMO. Thirdly, they relate the required feedback rate with the achievable rate on the downlink channel. Real multi-user channel measurement data acquired with the Eurecom MIMO OpenAir Sounder (EMOS) is used. To the best of the knowledge, these are the first measurement results giving evidence of how MU-MIMO precoding schemes depend on the precoding scheme, channel characteristics, user separation, and codebook.