Abstract
Millimeter-wave (mm-wave) communication is the spectral frontier to meet the anticipated significant volume of high data traffic processing in next-generation systems. The primary challenges in mm-wave can be overcome by reducing complexity and power consumption by large antenna arrays for massive multiple-input multiple-output (mMIMO) systems. However, the circuit power consumption is expected to increase rapidly. The precoding in mm-wave mMIMO systems cannot be successfully achieved at baseband using digital precoders, owing to the high cost and power consumption of signal mixers and analog-to-digital converters. Nevertheless, hybrid analog–digital precoders are considered a cost-effective solution. In this work, we introduce a novel method for optimizing energy efficiency (EE) in the upper-bound multiuser (MU) - mMIMO system and the cost efficiency of quantized hybrid precoding (HP) design. We propose effective alternating minimization algorithms based on the zero gradient method to establish fully-connected structures (FCSs) and partially-connected structures (PCSs). In the alternating minimization algorithms, low complexity is proposed by enforcing an orthogonal constraint on the digital precoders to realize the joint optimization of computational complexity and communication power. Therefore, the alternating minimization algorithm enhances HP by improving the performance of the FCS through advanced phase extraction, which involves high complexity. Meanwhile, the alternating minimization algorithm develops a PCS to achieve low complexity using HP. The simulation results demonstrate that the proposed algorithm for MU - mMIMO systems improves EE. The power-saving ratio is also enhanced for PCS and FCS by 48.3% and 17.12%, respectively.
Highlights
The massive multiple-input multiple-output system operations on millimeter-wave aims to meet the anticipated emergence as key solutions and growth of traffic demands for high-data-rate multimedia access in fifth-generation (5G) systems [1]–[3].The growing mobile data traffic, such as those from smartphone and mobile internet users, can be supported through the availability of more bandwidth, which offers higher data rates for all users and capacity in a cellular mobile network
The EE with fully-connected structures (FCSs)/partially-connected structures (PCSs) algorithms can always maintain the best performance of EE = 3.7 Mbits/J and decreases the EE to 2.9 Mbits/J with increases the number of RF chains (NRF)
When the NRF is greater than the number of data streams (Ns), the hybrid precoding (HP) with the FCS can move toward the optimal baseband precoding (BBP)
Summary
The massive multiple-input multiple-output (mMIMO) system operations on millimeter-wave (mm-wave) aims to meet the anticipated emergence as key solutions and growth of traffic demands for high-data-rate multimedia access in fifth-generation (5G) systems [1]–[3]. The transmission rate can be improved by addressing the tradeoff between performance and hardware efficiency by employing the FCS/PCS with dynamic subarray and low-resolution phase shifters This approach proposes an iterative hybrid beamformer design to mitigate the performance loss by fixed subarrays connected for every RF chain to all transmission antennas [17]. Motivated by the abovementioned gap, we optimize EE and offer low computational complexity based on updating a phase extraction for constraint transmission power, and zero gradient-based iterative minimization algorithms, which increase the Ns compared with more RF chains in FCS and a PCS. The main objective of this study is to improve the EE by reducing the cost, PC, and number of RFs, based on the proposed effective alternating minimization algorithms to establish FCSs and PCSs. The FCS of HP design is performed by updating a phase extraction for constraint transmission power, and zero gradient-based iterative.
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