This paper reports multi-user D-MIMO system capacity calculations for 4x4 D-MIMO channels, simulated using transmission loss and indirect path loss variation models derived from channel sounding measurements made with a vector-network-analyser (VNA) based channel sounding system. The channel sounding measurements were made with a bandwidth of 500 MHz at centre frequencies of 2.4 GHz, 18 GHz, and 28 GHz, in a small cluttered study room. Transmission was from an emulated sector antenna mounted with a downtilt of 62.5 degrees above the suspended ceiling in the room at a height of 4 m above floor level. Reception was at 45 desk-topheight locations scattered throughout the room using an omni directional antenna at 2.4 GHz, and step-wise azimuth and elevation scanning horn antennas with 10 deg beamwidths in both planes, which scanned for maximum received power at 18 GHz and 28 GHz. Reported results show that, given the same average SNR, D-MIMO system capacities are approximately the same with no beam steering at UEs at 2 GHz and with beam steering at UEs at 18 and 28 GHz. In the scenario considered, between 20 dB and 25 dB and between 30 dB and 35 dB more system gain is required at 18 GHz and at 28 GHz, respectively, to achieve the same SNR as at 2 GHz. However, it is considered that when beams are steered at a UE to receive maximum power from specular reflections, it might be possible to avoid the deleterious effects of correlations in spatial transmission loss variations and interference. In this case, significant increases in outage capacity (e.g. 3 bits/s/Hz, compared with 1 bit/s/Hz, at SNR=6 dB) can be achieved at the same SNR, with respect to that in conventional 2 GHz systems, when the steering of narrow beams to the direction of maximum received power is employed.

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Keywords Channel modelling, D-MIMO, Indirect path communications, Mm wave indoor wireless systems, Radio propagation
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Conference 86th IEEE Vehicular Technology Conference, VTC Fall 2017
Bultitude, R.J.C, & Alkadamani, M. (Mohamad). (2018). Radio-propagation-measurement-based simulations of the capacity of multi-user D-MIMO indirect path communications systems in a small cluttered room at 2, 18, and 28 GHz. In IEEE Vehicular Technology Conference (pp. 1–5). doi:10.1109/VTCFall.2017.8287888