Sum Rate Analysis of MU-MISO Systems with ZF Beamforming over Composite Fading Channels

Ou ZHAO  Hidekazu MURATA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E98-A    No.2    pp.558-568
Publication Date: 2015/02/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E98.A.558
Type of Manuscript: Special Section PAPER (Special Section on Wideband Systems)
spatially correlated shadowing,  correlated rayleigh fading,  sum rate,  zero-forcing beamforming,  MU-MISO,  

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The performance of multiuser multiple-input single-output (MU-MISO) systems is not only affected by small-scale multipath fading but also by large-scale fading (i.e., shadowing) and path loss. In this paper, we concentrate on the sum rate distribution of MU-MISO systems employing linear zero-forcing beamforming, accounting for both multipath fading and shadowing effects, as well as spatial correlation at the transmit and receiver sides. In particular, we consider the classical spatially correlated lognormal model and propose closed-form bounds on the distribution of the achievable sum rates in MU-MISO systems. With the help of these bounds, we derive a relationship between the interuser distance and sum rate corresponding to 10% of the cumulative distribution function under different environmental conditions. A practical conclusion from our results based on the considered system is that the effect of spatially correlated shadowing can be considered to be independent when the interuser distance is approximately five times the shadowing correlation distance. Furthermore, a detailed analysis of the effects of composite channel attenuation consisting of multipath fading and shadowing is also provided.