MIMO Techniques Research Articles

Performance Analysis of Dual-Beam Free Space Optical Communication Link under Dust and Rain Conditions

Free space optical (FSO) communication has become an enduring and well-established communication technology in the last few decades with several advantages of high data rate, enormous bandwidth, low power consumption, transportable technology without right of way, and inherently secure line of a sight communication system. The invisible, intensity-modulated signal of light propagated through the air and detected on the receiver side experiences attenuation because of uneven distribution of rain droplets, suspended dust aerosol particles, and the droplet size distribution of fog particles in atmospheric layer degrade performance of FSO communication link. The ever-increasing demand for high data rate has quest for an innovative research for a communication link. In this paper, the performance of a dual-beam FSO communication link is evaluated under rain and dust as attenuation conditions. The system parameters, such as link distance transmitted and received power, link distance, diameter of transmitter and receiver aperture, and divergence angle, are optimized for a metropolitan FSO communication link. Dual-beam FSO communication signal propagated through an estimated attenuation level at 30 dBm transmitted power for link distance up to 2.5 km. The optical power splitter and power combiners are used in the simulation to estimate different channel parameters without the MIMO technique. The information signal of the 10 Gbps data rate is internally modulated using the NRZ generator, externally modulated by the Mach-Zehnder, and an optical signal transmitted through a dual-beam optical spectrum frequency of 193.1 THz using power splitter technique apart from each other. A comprehensive analysis is performed to design and assess robust optical communication systems through efficiency parameters such as received power, optical signal-to-noise ratio (OSNR), bit error rate (BER), and Q-factors. Results show that received optical power is a weather-dependent variable that shows a decreasing pattern as weather attenuation increases. Likewise, Q-factor and OSNR show similar decreasing trend with introduction of rain and dust as attenuator; however, BER increases in presence of attenuation.

Resource optimization of MIMO using neural network for 5G communication

The principal objective of this work is to optimize the resources of massive MIMO techniques by an application of a neural network algorithm in order to reduce the manufacturing cost of 5G technology within the wireless peripheries of tropical regions. For plenty of annual precipitation in the tropical regions, the radio signals of these areas get attenuated in communicating any message i.e. signal fading occurs. Various diversity techniques have been used for diminishing signal fading in these tropical areas. MIMO technique is a spatial diversity technique used to minimize signal fading. In this paper, 1 × 1 to 256 × 256 MIMO techniques have been designed with the help of MATLAB and Xilinx system generator, and an 8 × 8 MIMO has been implemented in Xilinx Kintex7 FPGA. A CMOS logic technique has been incorporated to optimize the resources of different MIMO techniques, and for this purpose a two-layer feed forward neural network algorithm has been adopted. A comparison of the theoretical values obtained from the design by using both Xilinx system generator and Simulink with the values derived from the design by using CMOS logic gates, has been displayed in this paper. For neural network optimization, three types of training algorithms have been applied.

Survey on design and analysis of MIMO antenna array for 5G application

This paper is a Survey on Design and Analysis of MIMO Antenna Array for 5G Application. 5G is evolving as a technology that will employ both low and high frequencies. The Indian government has taken steps to make the 5G vision a reality. The impact of 5G in India on exponential data usage increase was examined. It goes over the 5G specifications that must be met in order to create a 5G system. Mobile network capabilities are rapidly expanding, driven by new requirements such as latency, traffic volumes, data speeds, and the need for consistent connectivity. Advanced antenna systems (AAS) provide cutting-edge beam shaping and MIMO techniques, which are useful for enhancing end-user experience, capacity, and coverage.

Experimental and Theoretical Analysis of Throughput of MIMO PLC Network

In this study, we mainly focused on a theoretical analysis of HomePlug 1.0 and an experimental analysis of modem data rates through a section of a PLC network with several configurations. We introduce the utilization of the MIMO technique to increase the throughput over a PLC channel. Besides, we propose a MIMO PLC channel model to evaluate the channel transfer function of MIMO PLC. We used an equivalent per-unit-length model of the indoor power line network to characterize the three-conductor cable. Based on this mathematical model, we analyzed the throughput of the PLC network with different household appliances. The equivalent circuit of each appliance is also given. The simulation results showed that the throughput is influenced by household appliances connected to the sockets of a MIMO PLC network. Moreover, we also compared the throughput between single and multi-antenna systems. Based on the simulation results, we found that the data rate increased with frequency. In addition, the performance of the MIMO PLC system was almost 90% higher than that of a SISO PLC system in terms of channel capacity.

Quality assessment for terrestrial digital video broadcast over optical wireless communication‐passive optical network under moderately turbulent regime with spatial diversity

SummaryThe preceding decade has seen successful rollout of 5G and convergence of broadcast broadband and telecom sector. The near future bandwidth demands for services such as advanced immersive multimedia are even more challenging. This has led to advent of 6G. The access technologies need to provide virtually unlimited data rates to support majority of applications in 6G. The optical wireless communication (OWC) with its inherent advantages is a potential enabler in this scenario. However, phenomenon such as atmospheric turbulence poses a serious degradation to performance of such systems. For multimedia services, end user perception is the ultimate quality indicator. To ascertain this quality in quantitative terms, full reference quality metrics are employed for communication purposes. In this paper, digital video broadcasting terrestrial (DVB‐T) videos with varying complexities are transmitted over OWC‐passive optical network (PON) architecture. For performance enhancement 2 × 2 repetitive coding MIMO is employed with maximal ratio combining receiver. A total of 6 video quality assessment (VQA) metrics are evaluated for the system w.r.t channel parameter as Rytov variance. For all the VQA metrics, an enhancement in the performance is observed by using MIMO technique. This performance improvement is more prominent for more complex video as compared to less complex video. As for the limiting case BER of 10−3 gives a limiting link distance of 1350 m; however with VQA metrics, the limiting case distance is 1280 m. By the use of 2 × 2 MIMO techniques, this distance enhances by 20–25 m.

A Novel Meander Line Metamaterial Absorber Operating at 24 GHz and 28 GHz for the 5G Applications

Fifth generation (5G) communication systems deploy a massive MIMO technique to enhance gain and spatial multiplexing in arrays of 16 to 128 antennas. In these arrays, it is critical to isolate the adjacent antennas to prevent unwanted interaction between them. Fifth generation absorbers, in this regard, are the recent interest of many researchers nowadays. The authors present a dual-band novel metamaterial-based 5G absorber. The absorber operates at 24 GHz and 28 GHz and is composed of symmetric meander lines connected through a transmission line. An analytical model used to calculate the total number of required meander lines to design the absorber is delineated. The analytical model is based on the total inductance offered by the meander line structure in an impedance-matched electronic circuit. The proposed absorber works on the principal of resonance and absorbs two 5G bands (24 GHz and 28 GHz). A complete angular stability analysis was carried out prior to experiments for both transverse electric (TE) and transverse magnetic (TM) polarizations. Further, the resonance conditions are altered by changing the substrate thickness and incidence angle of the incident fields to demonstrate the functionality of the absorber. The comparison between simulated and measured results shows that such an absorber would be a strong candidate for the absorption in millimetre-wave array antennas, where elements are placed in proximity within compact 5G devices.

Cylindrical Massive MIMO System with Low-Complexity Angle-Based User Selection for High-Altitude Platform Stations

High-altitude platform stations (HAPSs) are recognized as a promising technology for coverage extension in the sixth generation (6G) mobile communications and beyond. The purpose of this study is to develop a HAPS system with a coverage radius of 100km and high capacity by focusing on the following two aspects: array antenna structure and user selection. HAPS systems must jointly use massive multiple-input multiple-output (mMIMO) and multiuser MIMO techniques to increase their capacity. However, the coverage achieved by a conventional planar array antenna is limited to a circular area with a radius of only tens of kilometers. A conventional semi-orthogonal user selection (SUS) scheme based on the orthogonality of channel vectors achieves high capacity, but it has high complexity. First, this paper proposes a cylindrical mMIMO system to achieve an ultra-wide coverage radius of 100km and high capacity. Second, this paper presents a novel angle-based user selection (AUS) scheme, where a user selection problem is formulated as a maximization of the minimum angular difference between users over all user groups. Finally, a low-complexity suboptimal algorithm (SA) for AUS is also proposed. Assuming an area with a 100km radius, simulation results demonstrate that the proposed cylindrical mMIMO system improves the signal-to-interference-plus-noise ratio by approx. 12dB at the boundary of the area, and it achieves approx. 1.5 times higher capacity than the conventional mMIMO which uses a planar array antenna. In addition, the results show that the proposed AUS scheme improves the lower percentiles in the system capacity distribution compared with SUS and basic random user selection. Furthermore, the computational complexity of the proposed SA is in the order of only 1/4000 that of SUS.

Performance Analysis of Multi-User MIMO Schemes under Realistic 3GPP 3-D Channel Model for 5G mmWave Cellular Networks

Novel techniques such as mmWave transmission and massive MIMO have proven to present many attractive features able to support high data demand for 5G NR technologies. Towards the standardization of 5G networks, channel modeling has become an important step in order to test the reliability of theoretical studies. In this paper, we study the performance of a 5G network at mmWave range for the downlink. We consider a single trisectorized base station equipped with planar arrays, and we model users as a spatial Poisson process in a hexagonal grid. We adopt the latest 3GPP channel model described in TR 38.901 and we provide a thorough description and step-by-step tutorial of it along with our customizations and MATLAB scripts for channel generation in the presented scenario. Moreover, we evaluate the performance of Multi-User Multi-Layer MIMO techniques, such as Signal-to-Leakage-plus-Noise Ratio (SLNR) precoding and MMSE combined with different system configurations by means of achievable per-user rate.

A Transmitter Design for the Multi-beam CC-OFDM Azimuth Scanning MIMO Radar

A conventional phased array radar provides a high gain by transmitting coherent signals over a large number of antenna elements. However, it does not provide a full time-on-target because it produces beams that scan the whole angular view of the radar. This paper describes an implementation of circulating codes (CC) in azimuth scanning MIMO radar that adopts OFDM waveform. The CC MIMO technique can produce a beam toward a certain angle by applying an appropriate delay difference between the MIMO antennas that transmit the same waveform across the azimuth. The adoption of OFDM waveform in the CC MIMO radar, gives the possibility to apply the phase difference for beamforming in the frequency domain of the OFDM signals. CC-OFDM MIMO with spectrum division into sub-bands and use of orthogonal codes, allow for simultaneous transmission of orthogonal OFDM symbols that generate orthogonal beams toward different angles. This strategy makes it possible for the radar system to have multiple and simultaneous beamforming to provide a full-time coverage. Furthermore, the transmission of a series of orthogonal OFDM symbols in each beam enables the detection of long-range targets. By taking as an example the design of long-range surveillance radar, the paper discusses further issues pertinent to the implementation of the CC OFDM MIMO radar, including the beam squinting problem and its remedy, arrangement of the multiple beams, the radar system structure, use of Golay codes for orthogonalization and PAPR mitigation, use of software-defined radar that eliminates the need of amplitude and phase control in each transmitter, transmit scheduling for multi-beam long-range target detection, and multidimensional ambiguity function analysis. The latter indicates that the CC OFDM MIMO radar can achieve a high resolution in angle, range, and velocity, with beam isolation of -30 dB for neighboring beams and co-channel beams.

Channel Estimation and Prediction in a Pilot-Less Massive MIMO TDD Using Non-Coherent DMPSK

A novel time division duplex massive MIMO technique is proposed based on performing a pilot-less channel estimation in the uplink (UL) utilizing reconstructed differentially encoded data. Spatial multiplexing and differentially encoded data is applied both in the UL and in the downlink (DL). In this system, a reference signal is the first one of the differentially encoded streams in the UL and DL, and the pilots for data estimation are avoided while maintaining spatial multiplexing capabilities. To improve the channel estimation we propose to use a linear Wiener filter and we also propose different symbols placing strategies in an OFDM grid. We also propose a detection improvement of the UL data utilizing the predicted channels. We perform an analysis of the MSE of the blind channel estimation using the differentially encoded data and analyze the symbol-error-rate for both the UL and the DL when channel aging is considered. The analysis is corroborated via numerical results and the proposed scheme is shown to outperform its pilot-based counterpart.

Beyond 5G Without Obstacles: mmWave-over-Fiber Distributed Antenna Systems

Beyond-5G wireless systems require significant improvement to enable the Internet of Everything, offering ultra-reliability, ultra-low-latency and high data-rates for holographic telepresence, immersive augmented and virtual reality, and cyber-physical systems in Industry 4.0. The mmWave frequency band (30–300 GHz) provides the required bandwidths, but very challenging propagation conditions exist. Conventional co-located multi-antenna systems counter higher path loss, but are insufficient in challenging real-life scenarios with frequent non-line-of-sight conditions. For distributed massive MIMO systems or large intelligent surfaces, we advocate optically-enabled distributed antenna systems (DAS) to alleviate these issues. To ensure tight synchronization and scalability, we propose a mmWave-over-fiber based architecture with low-complexity high-performance remote antenna units (RAUs). Strategically distributing and integrating RAUs in the user equipments' environment yield high throughput and reliable coverage. We demonstrate a mmWave-over-fiber DAS yielding multi-Gb/s mmWave communication in a harsh indoor environment with non-line-of-sight conditions, measuring wireless data rates up to 24 Gb/s, by selecting the RAU yielding the best link quality, and up to 48 Gb/s, by leveraging distributed MIMO techniques.

Secure Communication for Cognitive Networks Based on MIMO and Spreading LDPC Codes

The existing cognitive radio (CR) systems lack the ability to deal with the attack of a pretended primary user (PPU), which can palsy cognitive network. To solve the problem, in this paper, a secure cognitive radio (CR) system is proposed. The proposed systems combines MIMO and spread spectrum techniques as well as low density parity check (LDPC) codes to cancel the electronic interference of PPU. The simulation results in Rayleigh flat-fading channel show that, comparing with MIMO cognitive system without the proposed method, the proposed approach can effectively cancel electronic interference from enemy and channel noises interference, and obtain about 9dB gain.

Surveying on MIMO Technology for Future Wireless Communication

Massive MIMO is an extension of traditional MIMO with the exception that the BSs in massive MIMO are equipped with large number of antennas, usually hundred or more. This large number of antennas provide several positive advantages towards wireless communication with respect to increasing volume of data traffic. Each antenna is capable of serving multiple users simultaneously leading to reduction in power consumption as well as data rate amplification. Additionally, narrow and more focused beams are pointed to individual user devices located at the cell edge thereby upgrading of downlink signal quality. Using massive MIMO technique also increases reliability of the links, reduces noise effects, and mitigates and interference. With increasing number of users gets service, the throughput of the system also increases.

Circularly Polarized Wideband Fabric Stealth Multiple-Input Multiple-Output Antenna for Ultrawideband Applications Useful for Wireless Systems Wearable on Garments

Stealth wearable wireless devices are gaining much attention in the personal security and fashion designing industry. A multiple-input multiple-output wideband circularly polarized antenna wearable on a dress (textile-related), which is immune to bending, is described in this paper, where a wearable on fabric dress application uses the MIMO techniques. It consists of two multiple-input multiple-output types of antenna elements: the resonating elements are created resembling a beautiful peacock shape and the ground plane is appropriately designed. A voltage is applied to each antenna element; the ground plane contains a microstrip transmission line-fed and a rectangular upside-down L-shaped (vertically flipped) strip used for circular polarizing. The antenna covers a 3 dB axial-ratio-band-width (ARBW) value of 5.20–7.10 GHz and impedance bandwidth (S11 less than −10 dB) of 03.60–13.0 GHz. The proposed attachable wearable fabric (textile) multiple-input multiple-output wideband antenna exhibits envelope correlation coefficient (ECC) <0.02, diversity gain (DG) >9.96, channel capacity loss (CCL) <0.2 b/s/Hz, total active reflective coefficient (TARC) <−10 dB, mean effective gain (MEG) ratio within ±0.5 dB. There is dual-sense circular polarization in this antenna and high isolation between resonating elements (higher than 18). A specific absorption rate (SAR) of the proposed antenna for human tissues specimen is also discussed for different situations related to the human body. The overall size of the proposed CP textile MIMO antenna is 34 : 5 × 42 × 1 mm3. Because of its clothing layers (textile), practical performance, and miniature size, the designed MIMO antenna may be helpful for wearable on cloths on human body wireless devices and systems. The proposed antenna can be made unrecognizable because of the beautiful peacock design that can easily mix with the designs of fabric (in the fashion dress). The simulated antenna was fabricated with the help of conventional manual fabrication techniques and tested in real-time situations. The edge-to-edge distance amid the MIMO radiating antennas is 14.2 mm, and the achieved isolation is greater than 18 dB after optimization of the proposed antenna.

BER analysis of dynamic FOV based MIMO-NOMA-VLC system

Visible Light Communication (VLC) has evolved as a breakthrough technology for beyond 5G networks by providing a wide license-free spectrum. In this paper, we build a robust NOMA-VLC Network which exploits the MIMO technique. In particular, a two-user 2 × 2 MIMO-NOMA-VLC system is proposed which considers on–off keying (OOK) modulation and L-pulse position modulation (L-PPM). The closed-form bit-error-rate (BER) expressions for the OOK and L-PPM modulated two-user MIMO based NOMA-VLC system are derived with the consideration of perfect and imperfect successive interference cancellation (SIC). The analysis shows that the proposed system marginally outperforms the single-input single-output SISO-NOMA-VLC system. The error performance of L-PPM modulated system is superior to that of OOK modulated system for L>2. Further, the increment in the number of photo detector (PD’s) at the receiver does not improve the error performance of the system significantly. To address this, two dynamic field of view (FOV) strategies are proposed for attaining the additional enhancement in error performance of OOK and L-PPM modulated MIMO-NOMA-VLC system. The 2 × 2 MIMO-NOMA-VLC system based on dynamic FOV strategy-2 completely outperforms the 2 × 2 MIMO-NOMA-VLC systems based on static FOV and strategy-1 in terms of error performance. The effect of power allocation co-efficient, α, on the error performance of the proposed systems is investigated. The best average error probability of a two-user MIMO-NOMA-VLC system is attained at α = 0.3. The simulation results are in close alignment with those of the analytical outcomes.

Physical Layer Security Analysis of Hybrid MIMO Technology

MIMO is a key enabling technology in the currently emerging 5G systems and future 6G-plus paradigms, such as heterogeneous networks, millimeter-wave networks, vehicular sensor networks, among others. The highly desired properties of MIMO such as its ability to supporting high data rates, improving energy and spectral efficiency, as well as overcoming the effects of shadowing and fading have made it increasingly attractive to the wireless communications industry. Nevertheless, a practical secure MIMO model with the required security levels to guarantee user information protection has still not been realized by the industry. In this work, we analyze and quantify the security performance of hybrid MIMO, which was originally proposed by the preceding work titled “Hybrid MIMO: A New Transmission Method For Simultaneously Achieving Spatial Multiplexing and Diversity Gains in MIMO Systems”. In the proposed method, special signal interference-canceling matrices, which are calculated based on the channel’s variations and randomness between the user and receiver, are superimposed with user data at the physical layer level before being transmitted to the receiver. The conducted performance analysis in this study indicates that the signal interference-canceling matrices provide absolute security (zero information leakage) against both internal and external eavesdroppers. Moreover, the new MIMO technique eliminates the need for any processing at the receiver, where users directly receive their intended signals, consequently lowering complexity and power consumption at the receiver. These are highly desirable properties for the future internet of things (IoT) devices as well as 6G and beyond technologies.

A survey on the characterization parameters and lifetime improvement techniques of wireless sensor network

Abstract Emerging technologies, such as the Internet of things (IoT), machine learning (ML) and machine-to-machine networks encourage deployment of large-scale wireless sensor networks (WSNs). The major problem in WSN is the limited energy of node batteries. Therefore, the efficient use of node energy for data sensing, processing and communication operations is important to maintain a fully operational network for longest period of time. Literature presents a wide range of lifetime maximization techniques for WSN such as resource allocation algorithm, clustering and routing, sleep–wake scheduling, energy harvesting, MIMO technique, Distributed source coding, genetic algorithm and sink mobility. These techniques effectively lessen the energy consumption and enhance the lifetime of the entire wireless sensor network in various applications. Besides energy consumption, the characterization parameters such as coverage and connectivity, communication and modulation schemes, operational environment, network parameters, node parameters and service parameters also have great impact on WSN performance. This paper presents a comprehensive survey of state-of-the-art research works that improves the performance of WSN by optimizing various network characterization parameters and lifetime maximization techniques. These results highlight the key issues which affects WSN performance and provide a roadmap for WSN designers for effective implementation of novel WSN strategies.

Massive MIMO Techniques for 5G and Beyond—Opportunities and Challenges

Telecommunications have grown to be a pillar to a functional society and the urge for reliable and high throughput systems has become the main objective of researchers and engineers. State-of-the-art work considers massive Multiple-Input Multiple-Output (massive MIMO) as the key technology for 5G and beyond. Large spatial multiplexing and diversity gains are some of the major benefits together with an improved energy efficiency. Current works mostly assume the application of well-established techniques in a massive MIMO scenario, although there are still open challenges regarding hardware and computational complexities and energy efficiency. Fully digital, analog, and hybrid structures are analyzed and a multi-layer massive MIMO transmission technique is detailed. The purpose of this article is to describe the most acknowledged transmission techniques for massive MIMO systems and to analyze some of the most promising ones and identify existing problems and limitations.

Performance Analysis of OFDM, FBMC and UFMC Modulation Schemes for 5G Mobile Communication MIMO systems

The rapid development in the field of Internet and mobile communication systems has demanded the technology of the 5th generation communication mimo systems to develop rapidly over the past few years. The name given to the next generation of wireless communication is 5G. Till now 4G provided the speed upto few mbps but the main drawback lies in reproducing the real time applications. In this scenario, 5th generation systems come into picture. 5g modulation schemes are developed exclusively for the Internet, video, voice, and data services. The ODFM has few disadvantages high peak power to average power ratio resulting in requirement of the high-power amplifiers. So, to overcome this problem, 5g modulation schemes Filter bank multi carrier systems and universal filter multicarrier systems are used. As we go higher the frequency range, there is an issue of frequency selectivity and thus by using the mimo techniques the problem of frequency selectivity can be solved. In this paper, we have compared the performance analysis of the Orthogonal frequency division multiplexing (OFDM) mimo system, Filter bank multicarrier (FBMC) mimo systems and Universal filter multicarrier (UFMC) mimo systems with respect to Bit error rate, power spectral density, data rate and issue of spectral confinement which is observed in FBMC and UFMC is resolved and thus reducing the complexity of the 5g system.

A Survey on Spatial Modulation and MIMO System for Emerging Wireless Communication

In this paper we have studied about Spatial Modulation (SM) in MIMO system. Spatial modulation is a unique and newly proposed technique. Spatial modulation is a multiple input multiple output technique which provides higher throughput and gain as compared to Quadrature Amplitude Modulation. Spatial modulation is a technique which enhances the performance of MIMO system. Spatial modulation and MIMO technique are used to attracted research for its high energy and spectral efficiency because it is working on single RF chain. This paper has considered the advantages of spatial modulation and MIMO systems, using different technique to improve the bandwidth efficiency. Some of such MIMO systems applications are discussed wherein become a requirement for an emerging wireless communication system.