918 research outputs found
Low computational complexity for optimizing energy efficiency in mm-wave hybrid precoding system for 5G
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
Joint Hybrid Precoder and Combiner Design for mmWave Spatial Multiplexing Transmission
Millimeter-wave (mmWave) communications have been considered as a key
technology for future 5G wireless networks because of the orders-of-magnitude
wider bandwidth than current cellular bands. In this paper, we consider the
problem of codebook-based joint analog-digital hybrid precoder and combiner
design for spatial multiplexing transmission in a mmWave multiple-input
multiple-output (MIMO) system. We propose to jointly select analog precoder and
combiner pair for each data stream successively aiming at maximizing the
channel gain while suppressing the interference between different data streams.
After all analog precoder/combiner pairs have been determined, we can obtain
the effective baseband channel. Then, the digital precoder and combiner are
computed based on the obtained effective baseband channel to further mitigate
the interference and maximize the sum-rate. Simulation results demonstrate that
our proposed algorithm exhibits prominent advantages in combating interference
between different data streams and offer satisfactory performance improvement
compared to the existing codebook-based hybrid beamforming schemes
Codebook Based Hybrid Precoding for Millimeter Wave Multiuser Systems
In millimeter wave (mmWave) systems, antenna architecture limitations make it
difficult to apply conventional fully digital precoding techniques but call for
low cost analog radio-frequency (RF) and digital baseband hybrid precoding
methods. This paper investigates joint RF-baseband hybrid precoding for the
downlink of multiuser multi-antenna mmWave systems with a limited number of RF
chains. Two performance measures, maximizing the spectral efficiency and the
energy efficiency of the system, are considered. We propose a codebook based RF
precoding design and obtain the channel state information via a beam sweep
procedure. Via the codebook based design, the original system is transformed
into a virtual multiuser downlink system with the RF chain constraint.
Consequently, we are able to simplify the complicated hybrid precoding
optimization problems to joint codeword selection and precoder design (JWSPD)
problems. Then, we propose efficient methods to address the JWSPD problems and
jointly optimize the RF and baseband precoders under the two performance
measures. Finally, extensive numerical results are provided to validate the
effectiveness of the proposed hybrid precoders.Comment: 35 pages, 9 figures, to appear in Trans. on Signal Process, 201
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