scholarly journals Observations and Models of Time-Varying Channel Gain in Crowded Areas

2006 ◽  
Author(s):  
V. Sridhara ◽  
Hwee-Chul Shin ◽  
S. Bohacek
Keyword(s):  
Channel Gain ◽  
Time Varying ◽  
Time Varying Channel

scholarly journals The research methods of a time-varying channel model of the XCTD profiler

2015 ◽  
Vol 12 (5) ◽  
pp. 849-856 ◽  
Author(s):  
Yu Zheng ◽  
Yu Gao ◽  
Jing Fang ◽  
GuoMin Song ◽  
YingSheng Shang ◽  
...  
Keyword(s):  
Research Methods ◽  
Channel Model ◽  
Time Varying ◽  
Time Varying Channel

scholarly journals The Downlink Performance for Cell-Free Massive MIMO with Instantaneous CSI in Slowly Time-Varying Channels

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1552
Author(s):  
Tongzhou Han ◽  
Danfeng Zhao
Keyword(s):  
Power Control ◽  
Massive Mimo ◽  
Mimo Systems ◽  
Mimo System ◽  
Multiple Input Multiple Output ◽  
Time Varying ◽  
Input Multiple Output ◽  
Efficiency Performance ◽  
A Cell ◽  
Time Varying Channel

In centralized massive multiple-input multiple-output (MIMO) systems, the channel hardening phenomenon can occur, in which the channel behaves as almost fully deterministic as the number of antennas increases. Nevertheless, in a cell-free massive MIMO system, the channel is less deterministic. In this paper, we propose using instantaneous channel state information (CSI) instead of statistical CSI to obtain the power control coefficient in cell-free massive MIMO. Access points (APs) and user equipment (UE) have sufficient time to obtain instantaneous CSI in a slowly time-varying channel environment. We derive the achievable downlink rate under instantaneous CSI for frequency division duplex (FDD) cell-free massive MIMO systems and apply the results to the power control coefficients. For FDD systems, quantized channel coefficients are proposed to reduce feedback overhead. The simulation results show that the spectral efficiency performance when using instantaneous CSI is approximately three times higher than that achieved using statistical CSI.

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