Capacity Of MIMO Systems Research Articles

Coverage Probability and Ergodic Capacity of Cell-Free Massive MIMO System

Coverage Probability and Ergodic Capacity of Cell-Free Massive MIMO System

MIMO System Capacity based on Multiple fading channels and varying numbers of antennas including the comparison of MIMO-NOMA and MIMO-OMA

MIMO System Capacity based on Multiple fading channels and varying numbers of antennas including the comparison of MIMO-NOMA and MIMO-OMA

Enhancing MIMO Capacity Through Space-Time Coding: Analysis And Design Framework

Space-time coding combines time and space to generate codewords, transmitting signals in both time and space domains. This leads to not only diversity and coding gains but also reduces the impact of multipath fading, resulting in high spectral efficiency. This paper examines the challenges in implementing space-time coding to enhance the capacity of MIMO systems. It analyzes the principle, design objectives, and criteria of space-time coding, providing a basic design framework, based on the space-time coding (STC) system model. .STC and MIMO have proven to be effective in improving system capacity, reliability, and overall performance in wireless communication. They have been applied in various fields such as wireless local area networks (WLANs), cellular networks, satellite communication, and wireless body area networks (WBANs). The use of space-time coding in 5G massive multi-antenna technology improves diversity and gain, resulting in higher communication throughput, leading to increased research in the field.

Capacity Analysis and Data Detection of OvTDM-MIMO System

It is well known that the channel capacity of traditional MIMO systems is positively correlated with the number of antennas, so MIMO systems usually use more antennas to meet higher system capacity requirements, which is increasingly conflicting with the miniaturization requirements of portable devices. To overcome the above problems, a new OvTDM-MIMO system is proposed, which can effectively improve the capacity of the system. This system introduces the overlapped time division multiplexing (OvTDM) technology into the MIMO system, which can further improve the channel capacity of the MIMO system by using a smaller number of antennas. This paper introduces the transceiver model of the OvTDM-MIMO system in detail and derives the channel capacity of the system based on mutual information theory. Compared with a conventional MIMO system, the OvTDM-MIMO system has the ability to improve channel capacity. Then, this paper proposes an OvTDM-MIMO symbol detection scheme based on an improved low-complexity Orthogonal Approximate Message Passing (OAMP) algorithm to solve the symbol detection problem caused by symbol correlation. The main design idea of this scheme is to use symbol correlation as the detection constraint and realizes joint symbol detection by combining adjacent symbols, avoiding the problem of excessive matrix size caused by Kronecker product operation. The simulation results show that the proposed detection algorithm can achieve similar performance to traditional MIMO system detection algorithms with low computational complexity.

Effects of Mutual Coupling on Degree of Freedom and Antenna Efficiency in Holographic MIMO Communications

The holographic multiple-input-multiple-output (MIMO) communications refer to the MIMO systems built with ultra-dense antenna arrays, whose channel models and potential applications have attracted increasing attentions recently. When the spacing between adjacent array elements is larger than half wavelength, the effect of mutual coupling can generally be neglected in current antenna designs. However, in holographic MIMO communications, the influence of strong mutual coupling on antenna characteristics is inevitable, resulting in distorted radiation patterns and low radiation efficiencies. In this paper, starting from the analytical correlation and efficiency models, we investigate how the mutual coupling affects the capacity of a space-constrained MIMO system from the aspects of degree of freedom (DOF) and antenna efficiency. The involved fundamental concepts of correlation, DOF, efficiency and mutual coupling are crucial for both antenna and wireless-communication engineers when designing emerging MIMO communication systems.

MIMO system capacity based on different numbers of antennas

This paper analyzed and compared the ergodic channel capacities of several typical channel systems (SISO, SIMO, MISO, MIMO) in independent identically distributed flat Rayleigh fading channels. The theoretical and simulation results show that the ergodic capacity of the MIMO channel increases linearly with the number of antennas.

Design of a UCA structure with maximum capacity for mmWave LOS MIMO systems

Design of a UCA structure with maximum capacity for mmWave LOS MIMO systems

Improvement of Diversity and Capacity of MIMO System Using Scatterer Array

A method of improving the diversity and capacity of multiple-input-multiple-output (MIMO) systems in nonisotropic multipath environments by loading a scatterer array is proposed. The difference between array diversity and super-resolution imaging is discussed first. The phase differences caused by the “effective space” between adjacent antenna elements are the critical factors of diversity enhancement. The scatterer array, which is made of cross-structure periodically, is placed on top of the antenna array to adjust the phase center of the radiation pattern of each antenna port. By increasing the “equivalent size” of the antenna array, the correlation of part of the adjacent ports in the antenna array is decreased; thus, the array diversity is improved. Through a set of comparative examples, the effectiveness of the scatterer array is clearly demonstrated.

Compact MIMO Systems Utilizing a Pixelated Surface: Capacity Maximization

Compact MIMO systems often suffer from degraded channel capacity due to spatial correlation. To overcome this issue, we propose a formulation for the channel capacity of a compact MIMO system that directly links it to the geometry of a pixelated surface embedded into the MIMO system. This formulation allows us to maximize the channel capacity of the MIMO system and straightforwardly obtain the optimum geometry for the pixelated surface that reduces spatial correlation. The key step in obtaining the formulation is to link the pixelated surface geometry to an impedance matrix that allows us to obtain an expression for the systems channel capacity. The formulation is general and can be applied to a wide variety of MIMO antenna systems and geometries. To demonstrate the versatility of the approach, we include a design for a compact 4-port planar inverted-F antenna (PIFA) array integrated with a pixelated surface. Simulations and experiments are provided to evaluate the performance of the compact MIMO system with and without optimization of the surface. It is shown that optimizing the geometry of the pixelated surface can increase channel capacity by 13% and energy efficiency by 19.9% compared to the system without optimization. The importance of the approach is that it provides a link between communication and electromagnetic formulations of MIMO antenna systems.

Antenna Selection and Detection Performance on Correlation Based Detection Systems

The increase data size transmitted in digital communication systems necessitates the use of high-capacity communication channels for the transmission of these data. To increase the channel capacity, MIMO systems are widely used. Antenna selection in MIMO systems is very important for efficient use of communication sources. Cognitive Radio systems generally aim to increase spectrum efficiency by using MIMO systems. Therefore, Cognitive Radio must find empty spectrum regions with spectrum detection methods. Spectrum detection performance is related to the antenna numbers in MIMO systems. Therefore, this study examines the effect of antenna numbers on detection performance in correlation-based detection method. Thanks to this study, the relationship between channel capacity, detection performance and antenna number for MIMO systems was investigated.

Analysis on Theory of MIMO and Research on Channel Capacity of MIMO System

By 2023, the average rate of global mobile network will increase to 44Mbps, 5G mobile communication network rate will reach 575Mbps [1]. Compared with 4G mobile communication, 5G mobile communication can support higher quality, higher transmission rate, higher user density and higher mobility performance, as well as lower delay and lower energy consumption scenarios [2]. With the advent of large-scale commercialization of 5G technology, the improvement of transmission performance can meet the growing communication needs of people well, and multiple antenna system (MIMO) has certain superiority in improving channel capacity. This article is aimed at introducing the working principle of MIMO system and the improvement of transmission performance brought by the technologies adopted. Furthermore, the proof of improvement of channel capacity brought by MIMO will be given. A channel model of MIMO communication system will be established through MATLAB, generating channel matrices randomly according to Gaussian distribution and then getting channel capacity by means of calculating the average value of multiple groups of data. The result shows that the channel capacity could improve greatly with the increase of the number of antennas under the condition of the same signal noise ratio (SNR), reaching the conclusion that MIMO system can effectively improve channel capacity.

Capacity Optimization of MIMO Systems Involving Conformal Antenna Arrays using a Search Group Algorithm

MIMO systems constitute a backbone of the fourth and fifth generations of wireless communication systems. The purpose of this paper is to introduce the involvement of conformal antenna arrays into MIMO systems. The Search Group Algorithm (SGA) is then used to further enhance the capacity of MIMO system employing conformal antenna arrays at both ends (Transmitter; Tx and Receiver; Rx). The results reveal that compared to the linear and 2D cases, conformal antenna arrays promise higher capacity values which motivates their employment in future MIMO communication systems.

Efficient modeling of low‐resolution millimeter‐wave transceivers for massive MIMO wireless communications systems

AbstractWe present a high‐fidelity measurement‐based nonlinear model of low‐complexity millimeter‐wave transmit and receive circuits for design and analysis of 1‐bit on‐off‐key (OOK) massive MIMO wireless communications systems. The receive model is based upon a fabricated 38 GHz energy detector, representative of state‐of‐the‐art OOK millimeter‐wave receivers. The model is validated with measurements and includes nonlinear noise modeling. Performance of a large‐scale massive MIMO system is predicted with the model, and predictions are compared against a 4‐transmit‐element, N‐receive‐element testbed. Finally, we compute the channel capacity of several OOK massive MIMO systems, exploring tradeoffs in power consumption and number of transmit and receive cells. Results indicate a 1‐bit OOK array with low power pre‐amplifiers can achieve similar capacity to a classical linear receiver with less than one tenth the power consumption. The 1‐bit array compensates for the per‐cell simplicity by increasing the total number of cells while maintaining low overall power consumption.

Performance of Data-Rate Analysis of Massive MIMO System Using User Grouping

The major challenges in massive MIMO networks are to increase the system throughput and capacity with low complexity and reliability of the wireless communication system. The computational complexity and system capacity of massive MIMO (M-MIMO) systems depend on adequate user grouping, user selection, and antenna scheduling methods. Additionally, the interference of the M-MIMO system is reduced when used suitable signal processing schemes. In this paper, we proposed a novel circular user grouping technique to reduce system complexity. Later, semi-orthogonal user selection with three different combinations of user selection schemes and norm-based antennas scheduling method is used to achieve higher system capacity in M-MIMO systems. Moreover, simple linear zero-forcing and minimum mean square error signal processing schemes are used to minimize the user’s interference. The simulation results show that our proposed algorithm provides very low computational complexity, reduce the interference and higher the system capacity compare to the traditional M-MIMO system.

Capacity Analysis of Multiple-input-multiple-output System Over Rayleigh and Rician Fading Channel

This paper aims to analyze the channel capacity in terms of spectral efficiency of a multiple-input-multiple-output (MIMO) system when channel state information (CSI) is known using water-filling algorithm and unknown at the transmitter side which it has been shown that the knowledge of the CSI at the transmitter enhancing the performance, the random Rayleigh and Rician channel models are assumed. Ergodic capacity and outage probability are the most channel capacity definitions which are investigated in this study. MATLAB code is devised to simulate the capacity of MIMO system for different numbers of antenna nodes versus different signal-to-noise ratio (SNR) values. In addition, the outage capacity probabilities for vary transmission rate and SNR are discussed.

Uplink Sum Rate and Capacity of Hybrid Precoding mmWave Massive MIMO System

Uplink Sum Rate and Capacity of Hybrid Precoding mmWave Massive MIMO System

BER and Capacity Improvement for Multiuser MIMO System by MRT Precoding Technique

In recent years several of endeavors have been conducted in various papers to improve capacity and bit error rate performance of multiuser MIMO system. Every effort tried to increase gain of the individual stream between base station and users’ antennas while reducing the interference among multiple users and interference between streams of single user itself. All these papers adopted precoding techniques for beam forming of individual stream. Various papers have compared precoding techniques such as DPC, BD-ZF, BD-MMSE, BD-QR-MRL, and BD-QR-LRL. Block diagonalization technique is capable to reduce multiuser interference, but not able to combat interference between antennas of single user itself. BD combines with other techniques to overcome this problem. This paper also proposes a precoding technique called modified maximum ratio transmission, which is able to deal with the problem without much complexity. Simulation is done to compare all precoding technique with MRT. The paper tests the precoding techniques on the parameters of BER and capacity, to achieve optimum receiver performance. BER curve and capacity curve are plotted to conclude the paper.

Improvement of Channel Capacity in a Multiple input Multiple Output LTE Radio System for GSM-Users Using Ideal Power Distribution Technique

Demand for high data rate in recent times has led to the development of LTE technology. There has been an increase of downlink and uplink speed of radio mobile communication to 10 M bps and 50 Mbps respectively. As mobile subscribers keep increasing, there is a need to enhance bandwidth for adequate data transmission. This study focused on the application of the MIMO system to enhance channel capacity by allocating more power to subchannels with better signal to noise ratio (SNR). The adaptive iterative water-filling technique was proposed and compared with other system capacity enhancement techniques such as conventional water filling and equal power allocation techniques by in incorporating the effect of path loss in wireless communication network The results presented show that incorporating path-loss model of LTE systems in the bands of 1800 MHz and 2500 MHz improves the MIMO system capacity. Also, increased in antenna size both at the transmitter and the receiver enhances the system capacity tremendously.

Fractal uniform circular arrays based multi-orbital-angular-momentum-mode multiplexing vortex radio MIMO

A radio wave driven by Orbital angular momentum (OAM) is called a vortex radio and has a helical wavefront. The differential helical wavefronts of several vortex radios are closely related to their topological charges or mode numbers. In physics, two or more radio waves with different mode numbers are orthogonal to their azimuth angles. With the development of radio communication technologies, some researchers have been exploring the OAM-based multi-mode multiplexing (multi-OAM-mode multiplexing) technologies in order to enhance the channel spectrum efficiency (SE) of a radio communication system by using the orthogonal properties of vortex radios. After reviewing the reported researches of OAM-based radio communication, we find that some breakthroughs have been made in the combination of OAM and traditional Multi-Input-Multi-Output (MIMO). However, the existing technology is not sufficient to support OAM-based MIMO system to achieve maximum the channel SE. To maximize the spectrum efficiency of OAM-based MIMO system, we present a reused multi-OAM-mode multiplexing vortex radio (RMMVR) MIMO system, which is based on fractal uniform circular arrays (UCAs). The scheme described in this study can effectively combine multi-OAM-mode multiplexing with MIMO spatial multiplexing. First, we present the generation of RMMVR MIMO signals. Second, under line-of-sight (LOS) propagation conditions, we derive the channels of the RMMVR MIMO system. Third, we separate the RMMVR MIMO signals using an orthogonal separation method based on full azimuth sampling. Finally, we introduce the method for calculating the channel capacity of the RMMVR MIMO system. Theoretical analysis shows that the scheme proposed in this study is feasible. Moreover, the simulation results show that spatial and mode diversity are obtained by exploiting fractal UCAs. However, to enhance the channel SE of RMMVR MIMO system, an interference cancellation method needs to be introduced for zero-mode vortex radios, and some methods of multi-OAM-mode beams convergence and mode power optimization strategy should be introduced in the future.

Capacity‐enhancement in MIMO systems using biomimetic electrically small antenna arrays

The authors investigate the performance of multi-input-multi-output (MIMO) communications systems that exploit biomimetic antenna arrays (BMAAs) with electrically small-aperture dimensions. By exploiting the mutual coupling between closely spaced radiating elements and extracting the maximum available power from all excitation modes of the array, BMAAs can significantly outperform conventional antenna arrays with similar aperture sizes. As a proof of concept demonstration, they examine the use of two-element BMAAs consisting of two $\lambda /4$λ/4 monopole antennas with variable element spacing in an MIMO system. The capacity of MIMO systems using such BMAAs is compared with those that use conventional antenna arrays with the same element types and spacing. Their simulation results demonstrate that using BMAAs can offer considerable capacity enhancements in an MIMO system. To experimentally verify these results, a prototype of a two-element BMAA operating at 615 MHz with element spacing of $\lambda /10$λ/10 and a regular array prototype with similar antenna elements and dimensions are fabricated and characterised. The performance of MIMO systems using these two antennas is modelled using numerical channel modelling using the measured antenna responses. These results are found to be in good agreement with theoretical predictions.