scholarly journals Optimising the Massive MIMO Downlink in the Presence of Power Amplifier Nonlinearities

2021 ◽  
Author(s):  
◽  
Peter Humphrey
Keyword(s):  
Massive Mimo ◽  
Mimo System ◽  
Realistic Model ◽  
Cell System ◽  
Base Station ◽  
A Cell ◽  
Downlink Signal ◽  
Moderate Cost ◽  
High Level ◽  
Mimo Downlink

<p>Massive MIMO is known for its high level of spectral efficiency in multipath rich environments. We present a detailed Massive MIMO cell system using maximum-ratio transmission (MRT) and zero-forcing (ZF) where energy efficiency is taken into account. This is done through the use of a realistic model of moderate performance and hence moderate cost power amplifiers (PAs) for the base station downlink, which could be applied in a practical Massive MIMO system. In the process of detailing the linear aspects of the Massive MIMO system, results for the normalisation factor and array gain are derived, which as far as the author is aware are original. These results are used to derive an expression to optimise the downlink signal-to-interference-and-noise-ratio (SINR) in a linear system, which is also original as far as the author is aware. A process is outlined to optimise the downlink SINR when nonlinear PAs are used and a simulation of a cell system is performed where the benefits of applying the nonlinear optimisation process are demonstrated.</p>

scholarly journals Optimising the Massive MIMO Downlink in the Presence of Power Amplifier Nonlinearities

2021 ◽  
Author(s):  
◽  
Peter Humphrey
Keyword(s):  
Massive Mimo ◽  
Mimo System ◽  
Realistic Model ◽  
Cell System ◽  
Base Station ◽  
A Cell ◽  
Downlink Signal ◽  
Moderate Cost ◽  
High Level ◽  
Mimo Downlink

<p>Massive MIMO is known for its high level of spectral efficiency in multipath rich environments. We present a detailed Massive MIMO cell system using maximum-ratio transmission (MRT) and zero-forcing (ZF) where energy efficiency is taken into account. This is done through the use of a realistic model of moderate performance and hence moderate cost power amplifiers (PAs) for the base station downlink, which could be applied in a practical Massive MIMO system. In the process of detailing the linear aspects of the Massive MIMO system, results for the normalisation factor and array gain are derived, which as far as the author is aware are original. These results are used to derive an expression to optimise the downlink signal-to-interference-and-noise-ratio (SINR) in a linear system, which is also original as far as the author is aware. A process is outlined to optimise the downlink SINR when nonlinear PAs are used and a simulation of a cell system is performed where the benefits of applying the nonlinear optimisation process are demonstrated.</p>

scholarly journals Zero-Forcing Precoding in the Measured Massive MIMO Downlink: How Many Antennas Are Needed?

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Zhe Zheng ◽  
Jianhua Zhang ◽  
Xiaoyong Wu ◽  
Danpu Liu ◽  
Lei Tian
Keyword(s):  
Massive Mimo ◽  
Mimo System ◽  
Signal To Noise Ratio ◽  
Base Station ◽  
Simple Expression ◽  
Mimo Channel ◽  
Channel Measurements ◽  
Zero Forcing ◽  
Theoretical Derivation ◽  
Mimo Downlink

In order to understand how many antennas are needed in a multiuser massive MIMO system, theoretical derivation and channel measurements are conducted; the effect of a finite number of base station (BS) antennas on the performance capability of Zero-forcing (ZF) precoding in a rich scattering channel is quantified. Through the theoretical analysis, the needed number of the transmit antennas for ZF precoder to achieve a certain percentage of the broadcast channel (BC) capacity will monotonically decrease with the increase of the transmit signal-to-noise ratio (SNR), and the lower bound of the needed transmit antennas is derived with a simple expression. Then the theoretical derivation is verified by simulation results, and the transmission performance is evaluated by channel measurements in urban microcell (UMi) scenario with frequencies of 3.5 and 6 GHz. From the measurement results, the ZF capability can be enhanced by improving the SNR and enlarging the antenna array spacing when the massive MIMO channel does not under a favorable propagation condition. Furthermore, because of the lower spatial correlation, the performance of ZF precoding at 6 GHz is closer to the theoretical derivation than 3.5 GHz.

A companding approach for PAPR suppression in OFDM based massive MIMO system

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ajay Kumar Yadav ◽  
Pritam Keshari Sahoo ◽  
Yogendra Kumar Prajapati
Keyword(s):  
Massive Mimo ◽  
Orthogonal Frequency Division Multiplexing ◽  
Mimo System ◽  
Multiple Input Multiple Output ◽  
Average Power ◽  
Base Station ◽  
Convex Optimization Problem ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Mimo Ofdm

Abstract Orthogonal frequency division multiplexing (OFDM) based massive multiuser (MU) multiple input multiple output (MIMO) system is popularly known as high peak-to-average power ratio (PAPR) issue. The OFDM-based massive MIMO system exhibits large number of antennas at Base Station (BS) due to the use of large number of high-power amplifiers (HPA). High PAPR causes HPAs to work in a nonlinear region, and hardware cost of nonlinear HPAs are very high and also power inefficient. Hence, to tackle this problem, this manuscript suggests a novel scheme based on the joint MU precoding and PAPR minimization (PP) expressed as a convex optimization problem solved by steepest gradient descent (GD) with μ-law companding approach. Therefore, we develop a new scheme mentioned to as MU-PP-GDs with μ-law companding to minimize PAPR by compressing and enlarging of massive MIMO OFDM signals simultaneously. At CCDF = 10−3, the proposed scheme (MU-PP-GDs with μ-law companding for Iterations = 100) minimizes the PAPR to 3.70 dB which is better than that of MU-PP-GDs, (iteration = 100) as shown in simulation results.

scholarly journals The Downlink Performance for Cell-Free Massive MIMO with Instantaneous CSI in Slowly Time-Varying Channels

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1552
Author(s):  
Tongzhou Han ◽  
Danfeng Zhao
Keyword(s):  
Power Control ◽  
Massive Mimo ◽  
Mimo Systems ◽  
Mimo System ◽  
Multiple Input Multiple Output ◽  
Time Varying ◽  
Input Multiple Output ◽  
Efficiency Performance ◽  
A Cell ◽  
Time Varying Channel

In centralized massive multiple-input multiple-output (MIMO) systems, the channel hardening phenomenon can occur, in which the channel behaves as almost fully deterministic as the number of antennas increases. Nevertheless, in a cell-free massive MIMO system, the channel is less deterministic. In this paper, we propose using instantaneous channel state information (CSI) instead of statistical CSI to obtain the power control coefficient in cell-free massive MIMO. Access points (APs) and user equipment (UE) have sufficient time to obtain instantaneous CSI in a slowly time-varying channel environment. We derive the achievable downlink rate under instantaneous CSI for frequency division duplex (FDD) cell-free massive MIMO systems and apply the results to the power control coefficients. For FDD systems, quantized channel coefficients are proposed to reduce feedback overhead. The simulation results show that the spectral efficiency performance when using instantaneous CSI is approximately three times higher than that achieved using statistical CSI.

scholarly journals Optimal Low-Power Design of a Multicell Multiuser Massive MIMO System at 3.7 GHz for 5G Wireless Networks

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Michel Matalatala ◽  
Margot Deruyck ◽  
Emmeric Tanghe ◽  
Luc Martens ◽  
Wout Joseph
Keyword(s):  
Low Power ◽  
Communication Networks ◽  
Massive Mimo ◽  
Mimo System ◽  
Low Power Design ◽  
Base Station ◽  
Base Stations ◽  
Reference Network ◽  
Power Requirement ◽  
Time Frequency

Massive MIMO techniques are expected to deliver significant performance gains for the future wireless communication networks by improving the spectral and the energy efficiencies. In this paper, we propose a method to optimize the positions, the coverage, and the energy consumption of the massive MIMO base stations within a suburban area in Ghent, Belgium, while meeting the low power requirements. The results reveal that massive MIMO provides better performances for the crowded scenario where users’ mobility is limited. With 256 antennas, a massive MIMO base station can simultaneously multiplex 18 users at the same time-frequency resource while consuming 8 times less power and providing 200 times more capacity than a 4G reference network for the same coverage. Moreover, a pilot reuse pattern of 3 is recommended in a multiuser multicell environment to obtain a good tradeoff between the high spectral efficiency and the low power requirement.

Signal Detection Algorithms for Massive MIMO

2014 ◽  
Vol 1049-1050 ◽  
pp. 2063-2068
Author(s):  
Xiao Tian Wang ◽  
Long Xiang Yang
Keyword(s):  
Signal Detection ◽  
Massive Mimo ◽  
Large Scale ◽  
Mimo System ◽  
Base Station ◽  
Mobile Systems ◽  
Detection Algorithms ◽  
Fifth Generation ◽  
Base Station Antennas ◽  
Large Scale Antenna Systems

massive MIMO (also known as Large-Scale Antenna Systems),which is one of the key technologies for the fifth generation (5G) mobile systems, brings huge improvements in spectral efficiency and energy efficiency through the use of a large excess of antennas for base station. This paper analyses and simulates the performances of several signal detection algorithms under the massive MIMO system model. The results show that when the number of base station antennas is considerably larger than the number of users, even the simple signal detection algorithms can achieve good system performance.

scholarly journals On the Capacity and Transmission Techniques of Massive MIMO Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Mohamed Abdul Haleem
Keyword(s):  
Massive Mimo ◽  
Mimo Systems ◽  
Transmission Rate ◽  
Mimo System ◽  
Coupling Factor ◽  
Base Station ◽  
Power Sharing ◽  
System Capacity ◽  
Bit Rate ◽  
Channel Coupling

A massive MIMO wireless system is a multiuser MISO system where base stations consist of a large number of antennas with respect to number of user devices, each equipped with a single antenna. Massive MIMO is seen as the way forward in enhancing the transmission rate and user capacity in 5G wireless. The potential of massive MIMO system lies in the ability to almost always realize multiuser channels with near zero mutual coupling. Coupling factor reduces by 1/2 for each doubling of transmit antennas. In a high bit rate massive MIMO system with m base station antennas and n users, downlink capacity increases as log2⁡m bps/Hz, and the capacity per user reduces as log2⁡n bps/Hz. This capacity can be achieved by power sharing and using signal weighting vectors aligned to respective 1×m channels of the users. For low bit rate transmission, time sharing achieves the capacity as much as power sharing does. System capacity reduces as channel coupling factor increases. Interference avoidance or minimization strategies can be used to achieve the available capacity in such scenarios. Probability distribution of channel coupling factor is a convenient tool to predict the number of antennas needed to qualify a system as massive MIMO.

scholarly journals Secure Massive MIMO System with Two-Way Relay Cooperative Transmission in 6G Networks

2020 ◽  
Author(s):  
Yumeng Su ◽  
Hongyuan Gao ◽  
Shibo Zhang
Keyword(s):  
Massive Mimo ◽  
Mimo System ◽  
Multiple Input Multiple Output ◽  
Base Station ◽  
Cooperative Transmission ◽  
Transmission Mode ◽  
Security Issue ◽  
Legitimate User ◽  
Input Multiple Output ◽  
Multiple Relay

Abstract With the advent of Internet of Everything (IoE) and the era of big data, massive multiple-input multiple-output (MIMO) is considered an essential technology to meet the growing communication requirements for beyond 5G and the forthcoming 6G networks. This paper considers a secure massive MIMO system, where the legitimate user and the base station (BS) exchange messages via two-way relays with the presence of passive eavesdroppers. To achieve the trade-off between the physical-layer security and communication reliability, we design a cooperative transmission mode based on multiple-relay collaboration, where some relays broadcast the received signals and other relays act as friendly jammers to prevent the interception by eavesdroppers. A quantum chemical reaction optimization (QCRO) algorithm is proposed to find the most suitable scheme for multiple-relay collaboration. Simulation results highlight excellent performance of the proposed transmission mode under QCRO in different communication scenarios, which can be considered a potential solution for the security issue in future wireless networks.

scholarly journals Evaluation of different quantization resolution levels on the BER performance of massive MIMO systems under different operating scenarios

2021 ◽  
Vol 23 (3) ◽  
pp. 1493
Author(s):  
Hayder Khaleel AL-Qaysi ◽  
Tahreer Mahmood ◽  
Khalid Awaad Humood
Keyword(s):  
Massive Mimo ◽  
Large Scale ◽  
Influence Factor ◽  
Mimo Systems ◽  
Mimo System ◽  
Base Station ◽  
Analog To Digital ◽  
Simulation Performance ◽  
Hardware Costs ◽  
Ber Performance

The massive MIMO system is one of the main technologies in the fifth generation (5G) of telecommunication systems, also recognized as a highly large-scale system. Constantly in massive MIMO systems, the base station (BS) is provided with a large number of antennas, and this large number of antennas need high-quantization resolution levels analog-to-digital converters (ADCs). In this situation, there will be more power consumption and hardware costs. This paper presents the simulation performance of a suggested method to investigate and analyze the effects of different quantization resolution levels of ADCs on the bit error rate (BER) performance of massive MIMO system under different operating scenarios using MATLAB software. The results show that the SNR exceeds 12 dB accounts for only 0.001% of BER signals when the number of antennas 60 with low quantization a 2 bits’ levels ADCs, approximately. But when the antenna number rises to 300, the SNR exceeds 12 dB accounts for almost 0.01% of BER transmitted signals. Comparably with the BER performance of high quantization, 4 bits-quantization resolution levels ADCs with the same different antennas have a slight degradation. Therefore, the number of antennas is a very important influence factor.

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