Abstract
Symmetry-based sub-connected hybrid precoding is an energy-friendly structure in wireless communications. Most of the prior work set a diagonal constraint on the analog precoder and used a randomly set matrix as the initial analog precoder, which did not match the optimal channel conditions, leading to a decrease in spectral efficiency, and some had huge complexity when calculating the digital precoder. Aiming to solve these problems, this paper proposed a low-complexity hybrid precoding algorithm based on Initial value Acceleration-based Alternating Minimization (IAAM). Leveraging the special structure of analog precoder in sub-connected scheme, we design the analog precoder through low-complexity quadratic programming and use the least square method to obtain the digital precoder. Moreover, we design a heuristic algorithm with the objective function of maximizing the effective channel gain to calculate the initial analog precoder as the starting point for alternating minimization. The simulation results show that the spectral efficiency of this algorithm is at least 17.5% higher than the existing two traditional sub-connected algorithms. Additionally, it increases energy efficiency by at least 12.8% compa with the Orthogonal Matching Pursuit (OMP) algorithm. Its algorithm convergence speed is fast, which increases with the number of RF chains.
Highlights
Received: 30 December 2020Due to the rapid expansion of wireless network users, the scarcity of spectrum resources has become more and more severe, and people have gradually turned their attention to the millimeter wave, which has abundant spectrum resources [1,2]
Millimeter wave massive MIMO technology uces the physical size of the antenna array by ucing the antenna spacing through the millimeter wave characteristics, which in turn helps to increase the antenna array size to obtain larger array gain to resist attenuation in propagation [3]
We proposed an Initial value Acceleration-based Alternating Minimization (IAAM)-based algorithm to establish millimeter wave dynamic sub-connected hybrid precoding
Summary
Due to the rapid expansion of wireless network users, the scarcity of spectrum resources has become more and more severe, and people have gradually turned their attention to the millimeter wave, which has abundant spectrum resources [1,2]. In sub-connected hybrid precoding, which effectively increases the spectral efficiency, but its computational complexity brought by the convex optimization toolbox during each iteration is too high and it sets an extra diagonal constraint on the analog precoder, which does not match the channel conditions perfectly, resulting in low effective channel gain being obtained. Sungwoo Park et al [15] deduced the optimal solution of the dynamic sub-connected hybrid precoding scheme, but the calculation amount was too large They designed a low complexity heuristic algorithm based on minimizing the Minkowski-1 norm to allocate the antennas, but the spectral efficiency of this method is not ideal because the algorithm is greedy.
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