MIMO Technology Research Articles

The use of MIMO technology in open optical communication systems with indirect visibility to improve the reliability of information transfer

The use of MIMO technology in open optical communication systems with indirect visibility to improve the reliability of information transfer

A Tri-Band Shared-Aperture Antenna for (2.4, 5.2) GHz Wi-Fi Application With MIMO Function and 60 GHz Wi-Gig Application With Beam-Scanning Function

This article presents the design and the realization of a tri-band shared-aperture antenna operating at 2.4, 5.2, and 60 GHz. It puts these three bands of antennas within the same radiating aperture and then realizes the Wi-Fi application with MIMO function and the Wi-Gig application with beam-scanning function simultaneously. It consists of two dual-band printed inverted-F antennas (PIFAs) and two SIW leaky wave antennas. By using the structure-reused technology, PIFA for the Wi-Fi application and the SIW antenna for the Wi-Gig application can share the same radiator without adding an extra aperture area. Thus, the ratio of the radiating aperture utilization can be improved greatly. In addition, MIMO technology is also applied to the Wi-Fi antenna design. The envelope correlation coefficients (ECCs) calculated from the simulated and measured data are all lower than 0.04. The measured radiation efficiencies are 74% to 95% and 76% to 95% within these two bands, respectively. Moreover, due to the optimal layout of the whole design, the Wi-Gig antenna can obtain high gain and wide range of beam coverage at the same time. The measured peak gain is 12.29 dBi, and the beam coverage is ±36° from 57 to 64 GHz.

Pergroup and Joint Optimization of Max-Dmin Precoder for MIMO with LDPC Coding Using QAM Modulation

MIMO technology not only offers diversity and capacity gains, but also provides higher spectral efficiency and significant link reliability over SISO systems. Many methods are developed to exploit the diversity offered by multi-antenna systems such as Alamouti code and spatial multiplexing that do not require transmitter-side channel status information (Tx-CSI). Other power allocation optimization techniques, also known as precoding, require a full or partial Tx-CSI. These techniques aim to transform the signal before transmission according to different criteria, among which the minimal Euclidean distance seems to be very effective and continues to interest the researchers. Given perfect channel state information at both sides of the communication, we propose in this paper a novel design of wireless transmission schemes that joint the minimal Euclidean distance precoder and error correction coding based on the non-binary low-density parity-check code (NB-LDPC), to finally determine a power allocation optimization solution that adapts a linear precoding block to an NB-LDPC encoded MIMO transmission. In this paper we use a quadrature amplitude modulation (QAM), over a Rayleigh fading channel with a maximum likelihood detection. Simulations results in term of bit error rate confirmed that NB-LDPC codes are particularly well suited to be jointly used with precoding schemes based on the maximization of the minimum Euclidean distance criterion.

GWO Based Optimal Channel Estimation Technique for Large Scale Mimo in LTE Network

The Wireless Systems Are Employed With More Number Of Antennas For Fulfilling The Demand For High Data Rates. In Telecommunication, Lte-A (Long Term Evolution-Advanced) Is A Well-Known Technology Intended For Wireless Broadband Communication Aimed At Data Terminals And Mobile Devices. Multiple Input Multiple Output (Mimo) Technology Is Used By Lte Which Is Also Known As Fourth Generation Mobile Networks To Attain Very High Data Rates In Downlink And Uplink Channels. Though The Mimo Systems In Massive Mimo Are Provided By Multiple Antennas, The Design Of The Appropriate Non-Erroneous Detection Algorithm Is A Major Challenge. Also, With The Increase In Quantity Of Antennas, The System's Spectral Efficiency Begins To Degrade. So As To Deal With This Issue, A Proper Algorithm Has To Be Utilized For Channel Estimation. The Bio Inspired Algorithms Have Shown Potential In Handling These Issues In Communication And Signal Processing. So, Grey Wolf Optimization (Gwo) Algorithm Is Used In This Approach To Estimate The Most Optimal Communication Channel. Also, The Spectral Efficiency And Data Capacity Are Enhanced Using The Presented Approach. The Proposed Approach’s Performance Is Compared With The Existing Approaches. The Simulation Result Exposes That The Presented Channel Estimation Approach Is Far Better Than Existing Channel Estimation Approaches In Performance Metrics Such As Bit Error Rate, Minimum Delay, Papr, Spectral Efficiency, Uplink Throughput, Downlink Throughput And Mean-Squared-Error.

Comparative Analysis of MIMO OFDM System Using Different Fading Techniques

The MIMO technology utilizes different antennas at each terminal of a wireless link and greatly improves the link reliability and spectral efficiency of future wireless communication systems. This technology integrated with Orthogonal Frequency Division Multiplexing (OFDM), which is particularly proving a propitious entrant for upcoming next generation wireless systems including both mobile and fixed systems. It provides an attractive air-interface solution for next-generation wireless/cellular systems. In this paper Waterfilling algorithm has been used to optimize transmit power for maximizing the capacity. The Waterfilling algorithm successfully solved the problem of power allocation for MIMO-OFDM wireless network and adaptively allocate power to minimize BER performance and increasing the capacity in order to maintain the QoS requirements for a network. The proposed work is investigated by using Matlab tool.

Research on 5G Millimeter Wave Channel Estimation Algorithm

With the explosive growth in the number of communication users and the huge demand for data from users, Limited low-frequency resources have been far from being satisfied by users. The combination of Massive MIMO technology and millimeter-wave technology has brought new hope to users. In this paper, several basic algorithms are placed under the millimeter wave large-scale antenna channel for simulation research.

Recent Activities of 5G Experimental Trials on Massive MIMO Technologies and 5G System Trials Toward New Services Creation

In order to cope with recent growth of mobile data traffic and emerging various services, world-wide system trials for the fifth-generation (5G) mobile communication system that dramatically extends capability of the fourth-generation mobile communication system are being performed to launch its commercial service in 2020. In addition, research and development of new radio access technologies for 5G evolution and beyond 5G systems are beginning to be made all over the world. This paper introduces our recent activities on 5G transmission experiments that aim to validate Massive MIMO technologies using higher frequency bands such as SHF/EHF bands, that is, 5G experimental trials. Recent results of 5G system trials to create new services and applications in 5G era in cooperation with partners in vertical industries are also introduced.

Singular Value Decomposition Channel Estimation in STBC MIMO-OFDM System

The multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) technology is the combination of the OFDM and MIMO technologies, which could improve the system capacity and make efficient utilization of the frequency spectrum. This paper utilizes space-time block coding (STBC) to achieve diversity gains and combat the channel fading. However, channel estimation is an essential block for space-time block decoding (STBD). Many channel estimation methods are utilized for the single antenna OFDM system, but they cannot be directly applied to the multiple antennas system due to the interference from other antennas. In this paper, orthogonal pilot sequences are designed to suppress the interference of pilot symbols from other transmit antennas. This paper also derives a minimum mean square error (MMSE) channel estimation method in MIMO-OFDM systems. The MMSE method involves the inverse operation of the channel autocorrelation matrix, which has a large calculation complexity. To further reduce the complexity of the MMSE method, the singular value decomposition (SVD) is used to decompose the channel autocorrelation matrix, which avoids the inverse operation. Simulation results verify that the SVD channel estimation method with comb-type pilots and STBC can be effectively adapted to multipath propagation conditions.

The Usage of Time Reverse Technology to Improve The BER Performance and Transmission Rate of IR-UWB System

Ultra-Wideband (UWB) technology has so many striking characteristics which includes low sensitivity to fading, superior performance, low interference, easy to penetrate in walls as well as in floor. The main motive of this work is to analyze the capability of UWB technology as various aspects and improve its performance, since the main drawback of this system is that the power spectral density of the transmitted signal is rather limited. The MIMO technology may provide a solution by increasing the received SNR for the same transmission power, but the problem in this case is the spatial correlation resulted. To solve the problem two technologies are integrated along with the UWB using Time Reverse (TR) by TR-MIMO and TR-SIMO. Among these integrations, the robust performance of the UWB is analyzed by comparing the transmission rates for a given outage probability. In the last step, the (SIMO/MIMO)-UWB and TR-(SIMO/MIMO)-UWB were compared in terms of BER values to create the way of applying the UWB in so many applications.

Simple Multi-RAT RoF System With $2\times2$ MIMO Wireless Transmission

A simple multi-radio access technology (multi-RAT) capable radio over fiber (RoF) system with 2 × 2 multiple-inputmultiple-output (MIMO) wireless transmission is proposed and experimentally demonstrated. The transmission of sub-6 GHz and 60 GHz millimeter-wave (MMW) services is enabled by a dual-drive Mach-Zehnder modulator (DDMZM) and an optical interleaver. In the central office (CO), sub-6 GHz and 30 GHz signals are applied to the dual branches of the DDMZM which is biased at the quadrature point. After transmission over singlemode fiber (SMF), the two services are separated by the optical interleaver. One output port of the interleaver is used for delivering the sub-6 GHz signal while the other one is used for the generation and transmission of the 60 GHz MMW signal. Furthermore, we also demonstrate the MIMO technology can be used in the proposed architecture to improve the capacity. A proofof-concept experiment is performed to verify the feasibility of the proposed scheme. In the experiment, a 1.3 Gb/s orthogonal frequency division multiplexing (OFDM) signal at 55 GHz is transmitted over 25 km of SMF and 1 m 2 × 2 MIMO wireless distance while a 675 Mb/s OFDM signal at 0.375 GHz is delivered over 25 km of SMF at the same time.

A short survey on next generation 5G wireless networks

Current 4G - the fourth-generation wireless communication, which exists in most countries, represents an advance of the previous 3 generation wireless communication. However, there are some challenges and limitations, associated with an explosion of wireless devices, which cannot be accommodated by 4G. Increasing the proliferation of smart devices, the development of new multimedia applications, and the growing demand for high data rates are among the main problems of the existing 4G system. As a solution, the wireless system designers have started research on the fifth-generation wireless systems. 5G will be the paradigm shift that could provide with ultra-high data rate, low latency, an increase of the base station capacity, and the improved quality of services. This paper is a review of the changes through the evolution of existing cellular networks toward 5G. It represented a comprehensive study associated with 5G, requirements for 5G, its advantages, and challenges. We will explain the architecture changes – radio access network (RAN), air interfaces, smart antennas, cloud RAN, and HetNet. Furthermore, it discussed physical layer technologies, which include new channel modes estimation, new antenna design, and MIMO technologies. Also, it discussed MAC layer protocols. The article included three kinds of technologies: heterogeneous networks, massive multiple-input and output, and millimeter-wave. Finally, it explained the applications, supported by 5G, new features, various possibilities, and predictions.

Research on MIMO Spread Spectrum Underwater Acoustic Communication Based on r-Combined Mapping

The complex underwater acoustic channel greatly limits the information transmission capacity of the underwater acoustic communication system, which seriously affects the performance of the underwater acoustic communication system. Therefore, robust and high quality underwater acoustic communication has been faced with severe challenges. This paper combines MIMO technology and spread spectrum technology to develop the MIMO spread spectrum underwater acoustic communication system based on r-combined mapping, which achieves a high information transmission rate and a high frequency band utilization by spatial multiplexing.

Optimal Transmit Antenna Selection Using Improved GSA in Massive MIMO Technology

Massive Multiple Input Multiple Output (M-MIMO) systems depend on numerous antennas to transfer numerous data streams simultaneously in Wireless Network Systems. In M-MIMO systems, the optimal Transmit Antennas Selection remains as a major constraint. As the count of antennas is increased, the power or energy consumption also increases. In fact, for attaining higher capacity, more transmit antennas is required, which leads to an increase in power consumption. Hence, for solving these problems in M-MIMO systems, this paper intend to achieve the selection of optimal transmit antennas by considering a multi-objective problem that maximizes both the capacity and relative Energy Efficiency. For attaining this objective, the proposed novel optimization algorithm not only optimizes the number of transmit antennas but also optimizes which antenna has to be selected. Hence, for optimal selection of antennas, improved GSA is used here, based on a velocity vector, and hence the proposed scheme is termed as Modified Velocity vector based GSA (MV-GSA) that determines the number of antennas and how to select the antennas in an optimal way. Moreover, the adopted scheme is compared with conventional algorithms like Genetic Algorithm, Artificial Bee Colony, Particle Swarm Optimization, FireFly and conventional GSA and the results are obtained.

Massive MIMO, mm Wave and 5G Technology Insights and Challenges

The global broadband cellular demand is increasing exponentially resulting in a worldwide shortage of available bandwidths allocated for wireless transmission, leading to in depth research being carried out in the underutilized Millimeter Wave (mmWave) bands which occupy the frequencies above 3GHz in the frequency spectrum. The 5G technology is evolving rapidly from the current 3G and 4G networks deployed worldwide, and the mmWave technology plays a vital role in the future 5G networks. Massive MIMO will be unprecedented during the design considerations when utilizing mmWave data streams with not only less complexity but will also enhance the spectral efficiency of the wireless system economically. This paper looks at the 5G revolution, its advantage over 4G, the incorporation between 5G and mmWave technologies, and MIMO antenna design considerations. It will also highlight the challenges facing the above technologies, and some new technologies such as Ultra Dense Networks (UDN), smart cities and Li-Fi which will incorporate mmWave, MIMO and 5G technology.

Optimal Modulation Technique for MIMO FSO Link

In recent years, free space optical communication (FSO) has gained amorous importance and become an interesting alternative to radio frequency communication because of its numerous benefits over radio frequency communication. It is efficient, low power, high data rate, unlicensed spectrum, and large bandwidth wireless technology. Despite, these advantages FSO is prone to the atmospheric attenuation, but in order to compensate this problem the MIMO FSO system is considered to be a good solution. This paper analyzes the performance of 4*4 MIMO FSO system using different modulation schemes, NRZ, RZ, and CSRZ. The impact of varying, Link range, attenuation factor and transmits power on the performance of 4*4 MIMO FSO has been observed in terms of Quality factor and eye diagram while keeping the other parameters constant. The results show that the RZ modulation scheme using 4*4 MIMO FSO technique show better performance as compare to NRZ and CSRZ. For low attenuation and small link, RZ is superior to NRZ and CSRZ while for higher attenuation and larger link the performance of RZ and NRZ is equivalent. Overall RZ performs better than NRZ and CSRZ. It is also evident from the results that as the number of transmitter and receiver are increased, the efficiency of the system increases. With MIMO technology the performance of FSO system improves to a larger extent.

Security situation assessment for massive MIMO systems for 5G communications

Abstract MIMO technology is a key technology of 5G, which is widely used in next-generation scenarios such as heterogeneous networks, millimeter-wave networks, and automotive networks. How to build a large-scale MIMO system security situation assessment model for 5G has become the main topic of current concern. This paper analyzes the situational awareness theory of 5g-oriented MIMO system security. Firstly, based on the theory of MIMO system, the influence of MIMO system on 5G network security and the theory of situation awareness technology, the security situation awareness system model of 5g-oriented large-scale MIMO system is constructed. In the security situation assessment section of the MIMO system, according to the rules of evidence reasoning, of different active attack and passive eavesdropping two kinds of empowerment behavior under different attribute data, and then put the empowerment process of average power and large scale attenuation coefficient, interrupt probability, series, and maintain confidentiality gain data as model inputs, such as implementing MIMO system level of situation assessment. In the security situation prediction part of MIMO system, based on the actual situation level of the system as the criterion, 30 sets of experimental simulation data are used to predict the next moment situation level of the MIMO system. In order to verify the stability and validity of the model, MATLAB is used to simulate the experiment. The results show that the mean square error RMSE of different iterations is kept below 0.02, and the TSQ values of both sides are kept below 0.16. The overall prediction effect of the model was good, indicating that the system could provide effective decision support for 5G MIMO security situation prediction

SIC-MMSE Method based Wireless Precoding Technique for Millimetre-Wave MIMO System

Objectives: A communication method is proposed using Minimum Mean Square Error (MMSE) precoding and Successive Interference Cancellation (SIC) technique for millimetre-wave multiple-input multiple-output (mm-Wave MIMO) based wireless communication system. Background: The mm-Wave MIMO technology for wireless communication system is the base potential technology for its high data transfer rate followed by data instruction and low power consumption compared to Long-Term Evolution (LTE). The mm-Wave system is already available in indoor hotspot and Wi-Fi backhaul for its high bandwidth availability and potential lead to rate of numerous Gbps/user. But, in mobile wireless communication system this technique is lagging because the channel faces relative orthogonal coordination and multiple node detection problems while rapid movement of nodes (transmitter and receiver) occur. Methods/Improvement: To improve the conventional mm-wave MIMO nodal detection and coordination performance, the system processes data using symbolized error vector technique for linearization. Then the MMSE precoding detection technique improves the link strength by constantly fitting the channel coefficients based on number of independent service antennas (M), Signal to Noise Ratio (SNR), Channel Matrix (CM) and mean square errors (MSE). To maintain sequentially encoded user data connectivity and to overcome data loss, SIC method is used in combination with MMSE. Improvements: MATLAB was used to validate proposed system performance. Simulation analysis has shown that, with the increase number of antenna use, the spectral efficiency also increased and higher then millimetre-wave MIMO or Single MMSE system. This research observed that, hybrid controller or combined control method have the better efficiency then single method, where SIC-MMSE based hybrid controller is a good example. Keywords: Channel Matrix, Long-term Evolution, Millimetre-wave, Minimum Mean Square Error, Quantized System, Successive Interference-Cancellation, Wireless Communication

Progress report on visible light communication in intelligent transportation environment

With the continuous and rapid development of modernization and motorization, the number of cars in China has maintained a high growth, which leads to problems such as increased traffic congestion and frequent accidents. The emergence of intelligent transportation system can effectively solve problems and contradictions between people, vehicles and roads in real time. In recent years, the development of visible light communication in the intelligent transportation environment has been more and more rapid. This paper briefly summarizes the research and development of visible light communication in the intelligent transportation environment. First of all, the main interference factors of outdoor visible light communication are summarized: background light and atmospheric turbulence. Then, some methods and techniques to suppress or weaken them, such as the average aperture and channel coding mainly reduce the influence of atmospheric turbulence on outdoor optical communication, and the error rate of the outdoor environment experiment system is 10-3-10-7. Adaptive optical MIMO technology mainly inhibits the communication interference caused by background light. In the outdoor background light environment, the communication distance can reach 15m and the bit error rate is 10-4. Finally, the research direction of outdoor visible light communication technology and its application in the field of intelligent transportation are prospected.

Cost Reduction and Channel Capacity Enhancement of MIMO System Using Antenna Selection Techniques

MIMO technology has become very popular in a wireless communication system because of the many advantages of multiple antennas at the transmitting end and receiving end. The main advantages of MIMO systems are higher data rate and higher reliability without the need of extra power and bandwidth. The MIMO system provides higher data rate by using spatial multiplexing technique and higher reliability by using diversity technique. The MIMO systems have not only advantages, but also have disadvantages. The main disadvantage of MIMO system is that the multiple antennas required extra high cost RF modules. The extra RF modules increase the cost of wireless communication systems. In this research, the antenna selection techniques are proposed to minimize the cost of MIMO systems. Furthermore, this research also presents techniques for antenna selection to enhance the capacity of channel in MIMO systems.

Joint design of cooperative protocols and distributed beamforming for multi-hop cognitive radio networks

The increasingly crowded wireless spectrum has led to the need of new paradigms in wireless communications and the cognitive radio techniques that can offer promising solutions to the spectrum scarcity. In cognitive radio networks licensed primary users and unlicensed secondary users are allowed to coexist in the same frequency spectrum. Beamforming and MIMO technology can be used to minimize the interference from the secondary users to the primary users while improving the quality of communications when each node is equipped with multiple antennas to form an antenna array. However, equipping multiple antennas at each radio node is not feasible in many applications. In this paper, we consider the radio network with single antenna at each node. We first propose a cooperative network architecture in the network layer. The architecture consists of cooperative clusters used for distributed beamforming, and a routing backbone of the clusters that can avoid the interference to the primary users in the relay route. Distributed algorithms are designed for self-formation of the cooperative clusters and routing backbone. Then we propose a computationally efficient secondary users selection scheme in the link layer for the communications between two cooperative clusters while minimizing the interference to the primary users. The simulation results show that the proposed protocols and algorithms are effective and efficient in terms of time and energy.