Spatial separation of closely-spaced users in measured massive multi-user MIMO channels

Abstract

Abstract-Fully-synchronous measurements of a massive multi-user multiple-input multiple-output (MU-MIMO) radio propagation channel are presented. We evaluate the ability of a massive MIMO system to spatially separate users located close to each other in line-of-sight (LOS) propagation conditions. The system consists of a base-station (BS) antenna array equipped with 64 dual-polarized antenna elements (128 ports) arranged in a cylindrical configuration, and eight single-antenna users. The users are confined to a five-meter diameter circle and move randomly at pedestrian speeds. The BS antenna array is located on top of a 20 m tall building and has LOS to the users. We examine user separability by studying singular value spread of the MU-MIMO channel matrix for several subsets of BS antenna array ports, along with sum-rate capacity and achievable sum-rates with both zero-forcing and matched-filtering linear precoders. We also analyze the performance of the user with the lowest rate. Finally, a comparison between the performance offered by the massive MIMO system and that of a conventional MU-MIMO system is provided. To the best of our knowledge, this is the first report of fully-synchronous dynamic measurements of a massive MIMO system. Our investigation shows that even users located close to each other in LOS propagation conditions can be spatially separated in a massive MIMO system.

Massive MIMO Performance—TDD Versus FDD: What Do Measurements Say?

“…For fixed N , we say that A outperforms B ifc A (ρ, N ) >c B (ρ, N ), where A and B may be applied to different scenarios. With one exception 6 , the relative sum-ratesc A (ρ, N ) increase with increasing values of N . At N = 128, D-SUB and H-SUB achieve the sum-capacity of the channel, and D-GOB and H-GOB achieve the sum-rate of ZF with perfect CSI.…”

“…The horizontal gap between the curves of D-GOB and H-GOB in Fig. 3, and between those of D-SUB and H-SUB, represents the penalty due to the frequency selectivity of the channel, in 6 In scenario 3, the relative sum-rate of H-GOB decreases slightly when N goes from 1 to 2. This can happen because ZF is used based on partial CSI.…”

“…For that we consider measurement data of real Massive MIMO channels in the 2. 6 GHz band, and analyze the achievable sum-rates using beamsteering codebooks. The conclusion, summarized in detail in Sec.…”

Channel modeling and analysis for multipolarized massive MIMO systems

“…The UCA is another popular antenna structure in massive MIMO systems. For multipolarized UCA massive MIMO systems, all the antennas are uniformly spaced on a circular edge as shown in Figure . In our proposed multipolarized UCA massive MIMO systems scheme, if antenna A m is vertically polarized antenna, antenna A m + 1 will be horizontally polarized antenna and vice versa.…”

Indoor massive multiple-input multiple-output channel characterization and performance evaluation

“…The results showed that most of the theoretical benefits of massive MIMO can be observed over the measured channels. The system performances of massive MIMO based on outdoor channel measurement campaigns were evaluated in Gao et al (2012;, Payami and Tufvesson (2012), and Flordelis et al (2015). The investigated frequency is 2.6 GHz and the bandwidth is 50 MHz.…”