Spectral Efficiency of Distributed Large-scale MIMO Systems with ZF Receivers

摘要

Distributed multiple-input multiple-output (DMIMO)is a promising technique for next generation wirelessnetworks, which offers a remarkable spectral efficiency gain overthe conventional co-located MIMO (C-MIMO). In contrast to CMIMO,which can be regarded as a special case of D-MIMO,performance analysis of D-MIMO is a challenging problem. Thisis because radio channels between a user and the distributed radioports (RPs) are characterized by non-identical path-loss andshadowing effects which render the classical analytical methodsnon-tractable. In this paper, new accurate expressions for theuplink spectral efficiency of D-MIMO and C-MIMO systems arepresented and compared for given large-scale coefficients. Wefurther consider the uplink spectral efficiency for a single-celldistributed large-scale MIMO (D-LMIMO) system with linearzero-forcing (ZF) receivers, accounting for path loss along withshadow fading and multi-path fading effects. Exact expressionsfor the average spectral efficiency over shadow fading in theasymptotically very large number of RPs antennas regime isexplicitly derived, and a tight closed-form lower bound on theasymptotic spectral efficiency is presented. We demonstrate that,the transmit power of each user in D-LMIMO can be scaleddown proportionally to the inverse of the number of RP antennaswith no performance reduction. Moreover, we study the spectralefficiency of a D-MIMO in a multi-cell environment taking intoaccount accurate co-channel interference (CCI) models. Theseexpressions provide meaningful insights into the impact of SNR,RPs and user positions, number of RPs antennas, shadow fading,and out-of-cell interference on the spectral efficiency of D-MIMOover practical scenarios. Finally, numerical results are validatedby simulation to confirm our analysis.