197 research outputs found
Energy efficiency of mmWave massive MIMO precoding with low-resolution DACs
With the congestion of the sub-6 GHz spectrum, the interest in massive
multiple-input multiple-output (MIMO) systems operating on millimeter wave
spectrum grows. In order to reduce the power consumption of such massive MIMO
systems, hybrid analog/digital transceivers and application of low-resolution
digital-to-analog/analog-to-digital converters have been recently proposed. In
this work, we investigate the energy efficiency of quantized hybrid
transmitters equipped with a fully/partially-connected phase-shifting network
composed of active/passive phase-shifters and compare it to that of quantized
digital precoders. We introduce a quantized single-user MIMO system model based
on an additive quantization noise approximation considering realistic power
consumption and loss models to evaluate the spectral and energy efficiencies of
the transmit precoding methods. Simulation results show that
partially-connected hybrid precoders can be more energy-efficient compared to
digital precoders, while fully-connected hybrid precoders exhibit poor energy
efficiency in general. Also, the topology of phase-shifting components offers
an energy-spectral efficiency trade-off: active phase-shifters provide higher
data rates, while passive phase-shifters maintain better energy efficiency.Comment: Published in IEEE Journal of Selected Topics in Signal Processin
Performance Evaluation of Hybrid Precoder Design for Multi-User Massive MIMO Systems with Low-Resolution ADCs/DACs
This paper presents a comprehensive analysis and design of a hybrid precoding system tailored for mmWave multi-user massive MIMO systems in both downlink and uplink scenarios. The proposed system employs a two-stage precoding approach, incorporating UQ and NUQ techniques, along with low-resolution DACs in downlink and ADCs in uplink to address hardware limitations. The system considers Zero Forcing and Minimum Mean Square Error algorithms as digital precoding methods for the uplink scenario, while exploring the impact of different DAC resolutions on system performance. Extensive simulations reveal that the proposed system surpasses conventional analog beamforming methods, particularly in multi-user scenarios involving inter-user interference. In downlink, the system demonstrates a trade-off between SE and EE, achieving higher Energy Efficiency with NUQ. In uplink, NUQ and UQ converters exhibit similar performance trends regardless of the chosen combiner algorithm. The proposed system attains enhanced Spectral and Energy Efficiency while maintaining reduced complexity and overhead. The study significantly contributes to the advancement of efficient and effective mmWave multi-user massive MIMO systems by providing a thorough analysis of various quantization schemes and precoding techniques. The findings of this research are expected to aid in the optimization of 5G and beyond technologies, particularly in high-density deployment scenarios
Hybrid Precoder and Combiner Design with Low Resolution Phase Shifters in mmWave MIMO Systems
Millimeter wave (mmWave) communications have been considered as a key
technology for next generation cellular systems and Wi-Fi networks because of
its advances in providing orders-of-magnitude wider bandwidth than current
wireless networks. Economical and energy efficient analog/digial hybrid
precoding and combining transceivers have been often proposed for mmWave
massive multiple-input multiple-output (MIMO) systems to overcome the severe
propagation loss of mmWave channels. One major shortcoming of existing
solutions lies in the assumption of infinite or high-resolution phase shifters
(PSs) to realize the analog beamformers. However, low-resolution PSs are
typically adopted in practice to reduce the hardware cost and power
consumption. Motivated by this fact, in this paper, we investigate the
practical design of hybrid precoders and combiners with low-resolution PSs in
mmWave MIMO systems. In particular, we propose an iterative algorithm which
successively designs the low-resolution analog precoder and combiner pair for
each data stream, aiming at conditionally maximizing the spectral efficiency.
Then, the digital precoder and combiner are computed based on the obtained
effective baseband channel to further enhance the spectral efficiency. In an
effort to achieve an even more hardware-efficient large antenna array, we also
investigate the design of hybrid beamformers with one-bit resolution (binary)
PSs, and present a novel binary analog precoder and combiner optimization
algorithm with quadratic complexity in the number of antennas. The proposed
low-resolution hybrid beamforming design is further extended to multiuser MIMO
communication systems. Simulation results demonstrate the performance
advantages of the proposed algorithms compared to existing low-resolution
hybrid beamforming designs, particularly for the one-bit resolution PS
scenario
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