Multiple-input Multiple-output Wireless Communication Systems Research Articles

Array pattern synthesis with phase-only constraint based on scaled-ADMM algorithm

The utilization of constant modulus beamforming technology is prevalent in multiple-input multiple-output (MIMO) radar systems and MIMO wireless communication systems. This paper investigates the problem of phase-only pattern control and synthesis in linear antenna array systems. It imposes a fixed amplitude constraint on the excitation signal, which only involves a phase constraint. However, this constraint is NP-hard and non-convex. To effectively address this challenging problem, we propose an iterative solution based on the scaled form of ADMM. This solution provides a means to rapidly synthesize patterns and significantly contributes to mitigating interference in other directions. In addition, the convergence of the proposed method is proved theoretically, and it is further demonstrated that the algorithm converges to the KKT stationary point of the original problem. Finally, simulation results show that the proposed method is superior to the most advanced methods in terms of pattern synthesis and convergence speed.

A Hybrid of Encryption and Error Correction Method for Multiple-Input Multiple-Output Wireless Communication Systems

A Hybrid of Encryption and Error Correction Method for Multiple-Input Multiple-Output Wireless Communication Systems

A hybrid of encryption and error correction method for multiple-input multiple-output wireless communication systems

A hybrid of encryption and error correction method for multiple-input multiple-output wireless communication systems

Zero Forcing Uplink Detection Through Large-Scale RIS: System Performance and Phase Shift Design

A multiple-input multiple-output wireless communication system is analytically studied, which operates with the aid of a large-scale reconfigurable intelligent surface (LRIS). LRIS is equipped with multiple passive elements with discrete phase adjustment capabilities, and independent Rician fading conditions are assumed for both the transmitter-to-LRIS and LRIS-to-receiver links. A direct transceiver link is also considered which is modeled by Rayleigh fading distribution. The system performance is analytically studied when the linear yet efficient zero-forcing detection is implemented at the receiver. In particular, the outage performance is derived in closed-form expression for different system configuration setups with regards to the available channel state information (CSI) at the receiver. In fact, the case of both perfect and imperfect CSI is analyzed. Also, an efficient phase shift design approach at LRIS is introduced, which is linear on the number of passive elements and receive antennas. The proposed phase shift design can be applied on two different modes of operation; namely, when the system strives to adapt either on the instantaneous or statistical CSI. Finally, some impactful engineering insights are provided, such as how the channel fading conditions, CSI, discrete phase shift resolution, and volume of antenna/LRIS element arrays impact on the overall system performance.

NON-ORTHOGONAL MULTIPLE ACCESS WITH V-BLAST UNDER OPTIMUM ORDERING

Non-orthogonal multiple access (NOMA) is expected to be one of the fundamental technologies of the upcoming 6G standard. This is mainly due to NOMA's potential in enabling all the users to utilize the same frequency band and the same time slot. In this paper, NOMA is implemented in a multiple-input multiple-output wireless communication system. By implementing zero-forcing V-BLAST algorithm into NOMA, spectral efficiency is improved, and successive interference cancellation is carried out. To perform optimum ordering, receive antennas’ signatures are compared and which signal to be decoded first is determined. Outage probability results of the system with optimum ordering and the same system without ordering are compared. In this way, a 3 dB gain is shown to be attained in terms of signal-to-noise ratio.

A Deep Learning-Based Intelligent Receiver for Improving the Reliability of the MIMO Wireless Communication System

Multiple-input–multiple-output (MIMO) technology is one of the most widely used communication technologies. However, with the increasing number of antennas, the complexity of the MIMO wireless communication receiver becomes higher and higher. On the other hand, the complex communication channels also raise up a great challenge to the reliability of the communication receiver system. With the rapid development and wide application of deep learning, it has been applied in the field of communication to solve some problems that are difficult to solve by the traditional methods, and thereby, improves the reliability of communication systems. Inspired by this idea, this article reviewed the signal processing process of the MIMO receiver system from the perspective of system reliability. Based on deep learning, the signal processing modules of the receiver system are jointly optimized, which changes the information recovery process of the traditional receiver and proposes the intelligent receiver for MIMO communication. In order to verify the system reliability of the intelligent receiver, this article analyzes it from the aspects of antenna numbers and channel conditions. The influence of different implementation methods of the intelligent receiver on the system reliability is also analyzed. Simulation results show that the proposed intelligent receiver for the MIMO wireless communication can recover information with a lower bit error rate and higher reliability compared with the traditional receiver under different conditions and antenna configurations.

Semi-Blind Multiuser Detection Under the Presence of Reconfigurable Intelligent Surfaces

A multiuser multiple-input multiple-output wireless communication system is analytically studied, which operates with the aid of a reconfigurable intelligent surface (RIS). The intermediate RIS is equipped with multiple elements and operates via random phase rotations to simultaneously serve multiple users. Independent Rayleigh fading conditions are assumed among the included channels. The system performance is analytically studied when the linear yet efficient zero-forcing detection is implemented at the receiver. In particular, the outage performance is derived in closed-form expression for different system configuration setups with regards to the available channel state information at the receiver. Further, a joint coherent/noncoherent linear detection is analytically presented. Finally, some new engineering insights are provided, such as how the channel state information and/or the volume of antenna/RIS arrays impact on the overall system performance as well as the arising efficiency on the performance/complexity tradeoff by utilizing the joint coherent/noncoherent scheme.

Performance of Full Rate Non-Orthogonal STBC in Spatially Correlated MIMO Systems

Spatial correlation is a crucial impairment for practical Multiple Input Multiple Output (MIMO) wireless communication systems. It is important to consider spatial correlation between antennas in actual communication scenario at both sides, i.e. transmit and receive side. Furthermore, we have considered nonorthogonal full rate STBC in MIMO systems equipped with four transmit antennas and four receive antennas in a quasi-static Rayleigh fading channel. In this paper, Bit Error Rate (BER) performance of full rate non-orthogonal Space Time Block code (STBC) is obtained using simulations in MIMO wireless communication systems. Spatial correlation is assumed between antennas at both the transmitter and the receiver sides. For this analysis, we have considered various transmit antenna spacing values of d t = 0.1π, 0.2π, and 0.4π keeping fixed d r = 0.1π and various receive antenna spacing values of d r = 0.1π, 0.2π, and 0.4π keeping fixed d t = 0.1π. The obtained results show that the transmitting diversity is more serious than the receiving diversity in the spatially correlated antenna environment for the specified signal-to-noise ratio. This study will be useful for actual wireless communication implementation where spatial correlation antennas are present in the practical environment of the MIMO wireless communication system.

Impact of Passive and Active Security Attacks on MIMO Smart Grid Communications

We consider multiple source nodes (consumers) communicating wirelessly their energy demands to the meter data-management system (MDMS) over the subarea gateway(s). We quantify the impact of passive and active security attacks on the reliability and security of the wireless communications system and the energy-demand estimation error cost in dollars incurred by the utility. We adopt a multiple-input multiple-output (MIMO) multiantenna-eavesdropper wiretap channel model. To secure the MIMO wireless communication system, the legitimate nodes generate artificial noise signals to mitigate the effect of the passive eavesdropping security attacks. Furthermore, we propose a redundant gateway design where multiple gateways are assumed to coexist in each subarea to forward the consumers' energy-demand messages. We quantify the redundant designs impact on the communication reliability between the consumers and the MDMS and on the energy-demand estimation error cost.

Zero Forcing Detection for Short Packet Transmission Under Channel Estimation Errors

A multiuser multiple-input multiple-output wireless communication system is analytically studied under the short-packet transmission regime. The practical scenario of channel estimation errors is adopted when the signals undergo Rayleigh channel fading conditions. Unlike most previous works, the channel estimation error term is treated as a signal rather than interference or noise, which may further enhance the overall system performance. The spatial multiplexing mode of transmit operation is considered, while the zero-forcing detection is applied at the receiver. New and exact closed-form expressions for the outage probability and total system goodput are derived. Capitalizing on the analytical results, some new engineering insights are also presented; such as the impact of channel estimation errors with respect to the number of antennas, transmit power, and/or coding rate.

The Secrecy Capacity Optimization Artificial Noise: A New Type of Artificial Noise for Secure Communication in MIMO System

In multiple-input multiple-output wireless communication system, artificial noise (AN) is designed to be aligned into the null space of the legitimate channel so that it has no effect on the legitimate channel. Meanwhile, AN will reduce the secrecy capacity of the eavesdropping channel so that AN increase the secrecy capacity of the wireless communication system. Nevertheless, AN technology only pays attention to the CSI of the legitimate channel but does not pay attention to the CSI of the eavesdropping channel so that the secrecy capacity of the system can be further improved. In this paper, we analyze the performance of traditional AN. A secrecy capacity optimization artificial noise for the whole communication system to further improve the system's secrecy capacity is proposed. The secrecy capacity optimization artificial noise is considered as a kind of artificial noise which is disadvantageous to the legitimate receiver but more disadvantageous to the eavesdropper. Furthermore, we further analyzed the technical details of AN technology and found the key factor affecting the secrecy capacity. Meanwhile, the secrecy capacity optimization artificial noise is effectively designed by applying these conclusions and the key factors of secrecy capacity optimization artificial noise affecting the secrecy capacity of the wireless communication system are described. The analysis and simulation results in practical environments show that the proposed method has a good performance on improving the secrecy capacity.

Improved VBLAST MAP: A Novel Point-to-Point Symbol Detection Algorithm for MIMO Wireless Communication Systems

A novel point-to-point symbol detection algorithm in multiple input multiple output (MIMO) system is proposed. This algorithm is an augmentation of two popular algorithms, namely, vertical Bell laboratories layered space-time (VBLAST) and maximum a posteriori probability (MAP). Here, layers are distinguished or ordered based on the a posteriori probabilities of output symbols and not on signal-to-noise ratio (SNR). For each layer, a set of a posteriori probabilities is computed for all output symbols using all possible signal constellations. The layer corresponding to the output symbol having minimum a posteriori probability is selected first from the set of a posteriori probabilities for detection by doing the comprehensive search over all the possible signal constellations. Then, the remaining layers are detected by the conventional VBLAST MAP technique. The relationship of MIMO symbol error rate (MIMO SER) versus MIMO symbol SNR is presented using simulations for 16x16 MIMO systems and 16-QAM constellation. The results show that the proposed algorithm outperforms conventional VBLAST MAP and improved VBLAST algorithms.

Symbol Error Rate Performance of Box-Relaxation Decoders in Massive MIMO

The maximum-likelihood (ML) decoder for symbol detection in large multiple-input multiple-output wireless communication systems is typically computationally prohibitive. In this paper, we study a popular and practical alternative, namely the Box-relaxation optimization (BRO) decoder, which is a natural convex relaxation of the ML. For iid real Gaussian channels with additive Gaussian noise, we obtain exact asymptotic expressions for the symbol error rate (SER) of the BRO. The formulas are particularly simple, they yield useful insights, and they allow accurate comparisons to the matched-filter bound (MFB) and to the zero-forcing decoder. For BPSK signals the SER performance of the BRO is within 3dB of the MFB for square systems, and it approaches the MFB as the number of receive antennas grows large compared to the number of transmit antennas. Our analysis further characterizes the empirical density function of the solution of the BRO, and shows that error events for any fixed number of symbols are asymptotically independent. The fundamental tool behind the analysis is the convex Gaussian min-max theorem.

Contribution of non-uniform EBG antenna arrays to the enhancement of MIMO channel capacity

The work proposes novel multiband and of low profile antenna arrays with hybrid type elements, for the realization of a MIMO (Multiple Input–Multiple Output) wireless communication system with great capacity. Each element is composed of a linear dipole integrated with a non-uniform Electromagnetic Band Gap (EBG) lattice. This EBG type, influences the system by two ways, the strong reduction of the Mutual Coupling (MC) among the closely positioned array's elements and the high radiation gain values of each element, inside wide space areas. Both of them make the antenna element capable of enhancing the MIMO channel capacity. It was ascertained by the results which were received taking into account globally, the MC and the radiation patterns of the antenna elements. The Spatial Channel Model (SCM) scenario for Urban Micro and Urban Macro environments was applied and the capacity calculation was made in one step which incorporates both the channel and the antenna characteristics. Results for the capacity at all three bands of operation are presented, for 10dB SNR level, along with respective ones received from dipole arrays in front of Perfect Electric Conductor (PEC). The comparison shows clearly the superiority of the proposed hybrid type array and its robust performance in wireless propagation scenarios.

Hybrid precoding in point‐to‐point massive multiple‐input multiple‐output systems based on normalised matrix adaptive method

The potential of millimetre wave frequencies band has motivated the study of large-scale antenna arrays to improve the spectrum efficiency of massive multiple-input multiple-output wireless communications systems. However, conventional fully digital precoding schemes, which require one radio frequency (RF) chain for each antenna, are cost prohibitive and have high-power consumption. To address these hardware limitations, this study considers a hybrid precoding scheme that provides high performance in terms of spectrum efficiency. By deducing the derivative of the spectrum efficiency function with respect to the phase matrix variable of the RF precoder, an efficient RF precoding scheme based on the normalised matrix adaptive method (NMAM) is proposed. Numerical simulations show that the NMAM achieves excellent performance approaching that of fully digital precoding, with relatively low computational complexity.

Improved Chase Detection Algorithm Based on SNR Maximum Sorted

Multiple-input multiple-output (MIMO) wireless communication systems could increase the spectral efficiency and system performance significantly. Maximum likelihood detection (MLD) algorithm provided the best bit error rate (BER) performance for MIMO communication system. Calculating complexity of MLD increased exponentially with the constellation size and the transmit antenna number. Original Chase detector, with lower calculating complexity, was combined of a list detector followed with some V-BLAST sub-detectors. There were error propagations in this algorithm. The order of signal detection was critical because of serial detection in Chase detector. In order to get better trade-off between detection performance and calculating complexity in MIMO wireless communication system, an improved Chase detection algorithm based on SNR maximum was presented here which could reduce error propagation efficiently. Parallel linear detectors were used in sub detectors to improve the bit error performance with lower complexity further more. The proposed algorithm could obtain proper trade-off between calculating complexity and detection performance, and simulation experiment results show its validity.

Constant Modulus Shaped Beam Synthesis via Convex Relaxation

Constant modulus shaped beam synthesis is widely employed in multiple-input–multiple-output (MIMO) radar systems and MIMO wireless communication systems to improve the effective power gain by using only phase adjustment. To achieve the maximum beam gain, we formulate a new optimization problem to maximize the main lobe gain and also properly suppress the sidelobes. However, this problem is NP-hard because of the constant modulus constraint. In order to efficiently solve this problem, we first relax the constant modulus constraint to a convex constraint, and then propose an alternating optimization algorithm to solve the relaxed problem. Interestingly, numerical results imply that the solutions of the relaxed optimization problem are (almost) constant modulus, and thus the convex relaxation is usually tight.

Improved Detection Algorithm for Multiple-Input Multiple-Output Wireless Communication Systems

Improved Detection Algorithm for Multiple-Input Multiple-Output Wireless Communication Systems

SNR and BER Analysis for Multiple Antenna System Using OFDM

Initially communication was carried out using analogue signal. Due to its various drawbacks, digital communication was introduced which has so many advantages over analogue communication and soon become very popular. Due to its low cost and easily reachable properties, wireless communication has become popular in communication.In the current scenario of modern wireless communication system, multiple input multiple output (MIMO) technique has emerged as one of the most efficient and significant method. This paper presents an analysis of MIMO system that has been introduced in the wireless communication to increase the diversity and to mitigate the effect of the channel fading phenomenon. In order to provide the transmit diversity, Space Time Block Code (STBC) is used in the Multiple input multiple output system. Effort has been made for deriving the Signal to noise ratio (SNR) and Bit error rate (BER) for different combination of the MIMO wireless communication system. SNR and BER have been computed for different combination of transmit antenna. The results of the simulation suggest that the performance of the MIMO system can be improved by increasing the diversity gain.

A Survey on Complementary-Coded MIMO CDMA Wireless Communications

In this paper, we present a comprehensive survey on complementary code (CC)-based multiple-input multiple-output (MIMO) code-division multiple access (CDMA) for futuristic wireless communications. This paper starts with the construction of CCs and then proceeds to describe the design of CC-based CDMA and MIMO wireless communication systems. Complementary-coded chip-level space–time coding offers a unique paradigm to implement multiuser MIMO systems, opening up a new dimension to combine multiple-access and multiple-antenna techniques in a unified platform for a possible system design optimization of a wireless communication system in the future. In this paper, we will also discuss various potential research topics and technical challenges that need to be tackled before a complementary-coded MIMO CDMA system can be implemented in practical wireless applications.