Abstract
A cell-free massive multiple-input multiple-output (MIMO) network-assisted full-duplex (NAFD) system has been proposed to satisfy the exploding demand of higher data transmission speed and more efficient communication. However, a growing number of users in a cell-free system inevitably leads to pilot contamination. In this paper, we analyze the ergodic spectral efficiency of cell-free massive MIMO NAFD system in the presence of pilot contamination. The cell-free massive MIMO NAFD system model has been investigated and both uplink and downlink channel state information (CSI) is estimated under spatially correlated channels. Under pilot contamination, the closed-form sum-rate expressions of the uplink with maximum ratio combination (MRC) receiver while downlink with maximum ratio transmission (MRT), and uplink with zero-forcing (ZF) receiver while downlink with ZF precoding schemes are derived based on large-scale random matrix theory. Numerical results show that under several environmental settings, the theoretical results match well with the simulated results and cell-free massive MIMO NAFD system has a better performance than time-division duplex (TDD) system. Moreover, simulation results show that the achievable sum-rate of using ZF/ZF could be more spectrally efficient compared to MRC/MRT because of its interference suppression capability.
Highlights
I N twenty-first century, information technology has became an integral part of our human beings society
The conclusion of this paper shows that when the maximum ratio combination (MRC)/maximum ratio transmission (MRT) signal processing method is adopted and the number of antennas per remote antenna unit (RAU) tends to infinity, the spectral efficiency tends to be constant
Based on these above figures, we could conclude that ZF/ZF scheme has a better performance than MRC/MRT scheme
Summary
I N twenty-first century, information technology has became an integral part of our human beings society. Y. Hu et al.: Spectral Efficiency of Network-Assisted Full-Duplex for Cell-Free massive MIMO System under Pilot Contamination. Analysis of a practical channel model performance was proposed in [35], which considers the channel correlation for different users and is available for scenes without massive scattering From this aspect, a standard unified cell-free massive MIMO NAFD system model is given in this paper. Considering the interferences and pilot contamination, the CSI that CPU obtained is imperfect On this basis, we focus on spectral efficiency analysis and derive the close-form expressions for the uplink and downlink asymptotic sum-rate system respec-. Based on the reciprocity of TDD uplink and downlink channels, we estimate CSI by sending pilot sequences from uplink and downlink users to RAUs simultaneously. The distribution of a circularly symmetric complex Gaussian (CSCG) random variable with m mean and variance σ2 is denoted as CN m, σ2 . −a.→s. denotes the almost sure (a.s.) convergence
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