Abstract
This paper proposes an estimation scheme of the number iterations for optimal Gauss–Seidel (GS) pre-coding in the downlink massive multiple input multiple output (MIMO) systems for the first time. The number of iterations in GS pre-coding is one of the key parameters and should be estimated accurately prior to signal transmission in the downlink systems. For efficient estimation without presentations of the closed-form solution for the GS pre-coding symbols, the proposed estimation scheme uses the relative method which calculates the normalized Euclidean distance (NED) between consecutive GS solutions by using the property of the monotonic decrease function of the GS solutions. Additionally, an efficient initial solution for the GS pre-coding is proposed as a two term Neumann series (NS) based on the stair matrix for improving the accuracy of estimation and accelerating the convergence rate of the GS solution. The evaluated estimation performances verify high accuracy in the downlink massive MIMO systems even in low loading factors. In addition, an additional complexity for estimating the number of the optimal iterations is nearly negligible.
Highlights
Multi-user (MU) massive multiple input multiple output (MIMO) is one of core techniques for high error performance and spectral efficiency in wireless communication systems without additional bandwidths and transmit powers
The number of multiplications for the GS pre-coding based on the proposed estimation scheme is increased slightly with respect to increased iAvg
The number of multiplications for the GS pre-coding based on the proposed estimation scheme is slightly higher than the number of multiplications for the conventional GS pre-coding since an additional complexity for the proposed scheme is only iNu multiplications for calculating normalized Euclidean distance (NED)
Summary
Multi-user (MU) massive multiple input multiple output (MIMO) is one of core techniques for high error performance and spectral efficiency in wireless communication systems without additional bandwidths and transmit powers. In [1,2], the ergodic spectral efficiency for the ZF is analyzed in the massive MIMO system and suboptimal performance is proven in both downlink and uplink systems. The number of iterations is a very important parameter in the GS and should be decided accurately prior to signal transmission in the downlink system and signal detection in the uplink system, respectively, for obtaining target error performance with minimum complexity. Coding in the downlink massive MIMO-OFDM system for optimal error performance. The optimal this paperdenotes proposes estimation schemefor of the the number of iterations for the GS uses pre-coding errorThus, performance theanerror performance.
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