Impact of deficient array antenna elements on downlink massive MIMO performance in RIMP and random-LOS channels

The Over-the-Air (OTA) characterization of large antenna systems need to be timeand cost-efficient. Among others, two potential candidates are OTA measurement environments emulating the Rich Isotropic MultiPath (RIMP) and the Random Line-Of-Sight (Random-LOS) channels. In the present paper we study the capacity loss of downlink massive multi-user multiple-input multiple-output (Massive MIMO) narrowband systems in these channels due to deficient antenna elements. We evaluate the downlink ergodic sum rate for the Zero-Forcing (ZF) and the Matched-Filtering (MF) precoders in these channels. We consider a single-cell system comprising a base station with 50 equidistant isotropic source antenna elements placed λ/2 apart and 5 users each equipped with a single isotropic antenna. No coupling effects between the array elements have been assumed. In the present study we show that both the RIMP and the Random-LOS can be used to identify deficient performance of Massive MIMO arrays.