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1
Sheu, Jeng-Shin, and Kuan-Ming Huang. "Performance Comparison for Single-User and Multi-User Network MIMO Cellular Systems with Power Management." Applied Sciences 11, no. 21 (November 2, 2021): 10298. http://dx.doi.org/10.3390/app112110298.
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Cellular mobile systems aim at aggressive spectrum reuse to achieve high spectral efficiency. Unfortunately, this leads to unacceptable interference near cell borders. To control this, network multi-input multiple-output (MIMO) can be adopted to improve coverage and cell-edge throughput through multi-cell cooperation. With network MIMO, multiple geographically separated base stations (BSs) cooperatively serve their cell-edge users (CEUs) using their antennas, acting together as a network of distributed antenna array. It can be single-user (SU) or multi-user (MU) network MIMO by coordinating channel allocation in adjacent cells. In this paper, we make a capacity comparison of SU- and MU-network MIMO. In network MIMO, a collaborative BS simultaneously serves its own cell-center users (CCUs) and CEUs, and the CEUs of other partner BSs under a power constraint. As a result, power management among three types of users (intra-cell CCUs/CEUs, inter-cell CEUs) becomes necessary. Accordingly, we propose power management methods to help raise the signal strength of inter-cell CEUs and in the meantime gratify the performance of intra-cell users. Simulation results show that MU-network MIMO with superposition coding offers much better CEU capacity than SU-network MIMO. As for the CCU capacity, MU-network MIMO is generally better than SU-network MIMO.
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Zhong, Shida, Haogang Feng, Peichang Zhang, Jiajun Xu, Lei Huang, Tao Yuan, and Yongkai Huo. "User Oriented Transmit Antenna Selection in Massive Multi-User MIMO SDR Systems." Sensors 20, no. 17 (August 28, 2020): 4867. http://dx.doi.org/10.3390/s20174867.
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A transmit antenna selection (TxAS) aided multi-user multiple-input multiple-output (MU-MIMO) system is proposed for operating in the MIMO downlink channel environments, which shows significant improvement in terms of higher data rate when compared to the conventional MU-MIMO systems operating without adopting TxAS, while maintaining low hardware costs. We opt for employing a simple yet efficient zero-forcing beamforming (ZFBF) linear precoding scheme at the transmitter in order to reduce the decoding complexity when considering users’ side. Moreover, considering that users within the same cell may require various qualities of service (QoS), we further propose a novel user-oriented smart TxAS (UOSTxAS) scheme, of which the main idea is to carry out AS based on the QoS requirements of different users. At last, we implement the proposed UOSTxAS scheme in the software defined radio (SDR) MIMO communication hardware platform, which is the first prototype hardware system that runs the UOSTxAS MU-MIMO scheme. Our results show that, by employing TxAS, the proposed UOSTxAS scheme is capable of offering higher data rates for priority users, while reasonably ensuring the performance of the common users requiring lower rates both in simulation and in the implemented SDR MIMO communication platform.
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Naeem, Muddasar, Antonio Coronato, Zaib Ullah, Sajid Bashir, and Giovanni Paragliola. "Optimal User Scheduling in Multi Antenna System Using Multi Agent Reinforcement Learning." Sensors 22, no. 21 (October 28, 2022): 8278. http://dx.doi.org/10.3390/s22218278.
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Multiple Input Multiple Output (MIMO) systems have been gaining significant attention from the research community due to their potential to improve data rates. However, a suitable scheduling mechanism is required to efficiently distribute available spectrum resources and enhance system capacity. This paper investigates the user selection problem in Multi-User MIMO (MU-MIMO) environment using the multi-agent Reinforcement learning (RL) methodology. Adopting multiple antennas’ spatial degrees of freedom, devices can serve to transmit simultaneously in every time slot. We aim to develop an optimal scheduling policy by optimally selecting a group of users to be scheduled for transmission, given the channel condition and resource blocks at the beginning of each time slot. We first formulate the MU-MIMO scheduling problem as a single-state Markov Decision Process (MDP). We achieve the optimal policy by solving the formulated MDP problem using RL. We use aggregated sum-rate of the group of users selected for transmission, and a 20% higher sum-rate performance over the conventional methods is reported.
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Handayani, Puji, and Beny Burhanusshomad. "Kinerja Multi-user MIMO OFDM dengan Block-Diagonalization Precoding." Jurnal JEETech 4, no. 1 (February 6, 2023): 15–19. http://dx.doi.org/10.32492/jeetech.v4i1.4103.
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Multiple-input multiple-output (MIMO) is a transmission technology that uses more than one antenna both on the transmitter side and on the receiver side. In the communication services, the system will involve more than one active user who uses one base station (BS) together so that it is called multi-user MIMO (MU-MIMO). This paper discusses the performances of MU-MIMO when it uses block diagonalization (BD) precoding and applies minimum mean squared error (MMSE) detector. As a comparison we also apply zero-forcing (ZF) detector. From the simulations that have been done, it is found that the MMSE had better performances than the ZF detector in terms of BER. We also consider the performance when users are moving. The simulation results show that BER performances are decrease slowly when users are moving.
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Raviv, Li-on, and Amir Leshem. "Scheduling for Multi-User Multi-Input Multi-Output Wireless Networks with Priorities and Deadlines." Future Internet 11, no. 8 (August 5, 2019): 172. http://dx.doi.org/10.3390/fi11080172.
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The spectral efficiency of wireless networks can be significantly improved by exploiting spatial multiplexing techniques known as multi-user MIMO. These techniques enable the allocation of multiple users to the same time-frequency block, thus reducing the interference between users. There is ample evidence that user groupings can have a significant impact on the performance of spatial multiplexing. The situation is even more complex when the data packets have priority and deadlines for delivery. Hence, combining packet queue management and beamforming would considerably enhance the overall system performance. In this paper, we propose a combination of beamforming and scheduling to improve the overall performance of multi-user MIMO systems in realistic conditions where data packets have both priority and deadlines beyond which they become obsolete. This method dubbed Reward Per Second (RPS), combines advanced matrix factorization at the physical layer with recently-developed queue management techniques. We demonstrate the merits of the this technique compared to other state-of-the-art scheduling methods through simulations.
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VijayaLakshmi, Dr M., and C. Anisha. "Massive MIMO-OFDM Transmission Without Cellular Networks Using Frequency - Selective Fading Channels." International Journal for Research in Applied Science and Engineering Technology 11, no. 10 (October 31, 2023): 1410–17. http://dx.doi.org/10.22214/ijraset.2023.56225.
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Abstract: For cell-free massive multi-input multi-output (CF-m-MIMO) across frequency-selective fading channels, this system introduces and determines the effectiveness of the orthogonal frequency-division multiplexing (OFDM)-based multi-carrier transmission. The CF-m-MIMO-OFDM system can accommodate a substantial user base and is flexible enough to offer a range of data rates for usage in a variety of contexts. With its scalability and flexibility, the CF-m-MIMO-OFDM transmission network can serve a large number of users at variable data rates. It is proposed to beamform in the frequency-domain conjugate, to choose a pilot, and to allocate resources differently for each user. User-specific resource allocation, pilot selection, and frequency-domain conjugate beamforming are all suggested. The CF-m-MIMO-OFDM system can support a large number of users and can offer varying data rates to accommodate a wide range of applications.
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Dai, Jian Xin, Jun Zhou, Jie Qi, Ming Chen, Tao Yuan, and Jun Zhao. "Optimal Power Analysis of Downlink Multi-User SA-MIMO Systems Use." Applied Mechanics and Materials 614 (September 2014): 530–34. http://dx.doi.org/10.4028/www.scientific.net/amm.614.530.
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This paper investigated the problem of transmit power minimization to meet the users’ outage probability constraints in downlink smart antennas-MIMO (SA-MIMO) systems. Firstly, a downlink multi-user SA-MIMO system model is established, and the transmit power optimization problem is formulated. The optimization problem jointly optimizes the beam-forming vectors and user outage probability. Then, the outage-based optimization problem is transformed into a geometric programming problem in which the beam forming vectors were obtained by maximum diagonal element (MDE) rule. Some numerical results show that the proposed method in this paper is viable and the transmit power in downlink SA-MIMO systems significantly descreases relative to traditional MIMO systems.
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Zhu, Mengyu, Shaoshuai Gao, Guofang Tu, and Deyuan Chen. "Multi-Access Edge Computing (MEC) Based on MIMO: A Survey." Sensors 23, no. 8 (April 11, 2023): 3883. http://dx.doi.org/10.3390/s23083883.
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With the rapid development of wireless communication technology and the emergence of intelligent applications, higher requirements have been put forward for data communication and computing capacity. Multi-access edge computing (MEC) can handle highly demanding applications by users by sinking the services and computing capabilities of the cloud to the edge of the cell. Meanwhile, the multiple input multiple output (MIMO) technology based on large-scale antenna arrays can achieve an order-of-magnitude improvement in system capacity. The introduction of MIMO into MEC takes full advantage of the energy and spectral efficiency of MIMO technology, providing a new computing paradigm for time-sensitive applications. In parallel, it can accommodate more users and cope with the inevitable trend of continuous data traffic explosion. In this paper, the state-of-the-art research status in this field is investigated, summarized and analyzed. Specifically, we first summarize a multi-base station cooperative mMIMO-MEC model that can easily be expanded to adapt to different MIMO-MEC application scenarios. Subsequently, we comprehensively analyze the current works, compare them to each other and summarize them, mainly from four aspects: research scenarios, application scenarios, evaluation indicators and research issues, and research algorithms. Finally, some open research challenges are identified and discussed, and these indicate the direction for future research on MIMO-MEC.
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Fang, Tianhao, Yangyang Gao, Chaoju Suo, Gangle Sun, Pengyu Chen, Wei Xiao, and Wenjin Wang. "A Multi-Beam XL-MIMO Testbed Based on Hybrid CPU-FPGA Architecture." Electronics 12, no. 2 (January 11, 2023): 380. http://dx.doi.org/10.3390/electronics12020380.
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To support more users and higher data rates in future communication networks, the extremely large-scale massive multiple-input multiple-output (XL-MIMO) is considered a promising technique. The booming research on XL-MIMO necessitates a reconfigurable XL-MIMO testbed that can be used to validate new research ideas in real wireless environments and collect data for XL-MIMO channel characteristics analysis. To provide such a reliable and convenient testbed, we designed a multi-beam XL-MIMO testbed based on the hybrid CPU-FPGA architecture and channel calibration schemes. The ability to customize modules makes our testbed a convenient verification platform for future communication systems. Moreover, numerous trial measurement results in the indoor near-field scenario with moderate user equipment (UE) mobility are presented, and the excellent performance indicates that our testbed is an ideal platform for the evaluation of XL-MIMO-related algorithms.
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Stankovic, Veljko. "Iterative successive MMSE multi-user MIMO transmit filtering." Facta universitatis - series: Electronics and Energetics 20, no. 1 (2007): 45–55. http://dx.doi.org/10.2298/fuee0701045s.
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In this paper we introduce a novel linear preceding technique. It was previously reported in the literature that when the user terminals are equipped with one antenna, minimum mean-squared-error (MMSE) in combination with successive interference cancellation is optimum on the uplink, while MMSE preceding in combination with Tomlinson-Harashima preceding (THP) is optimum on the downlink. The linear preceding technique introduced in this paper is based on the modified MSB criterion. It can serve the users that are equipped with arbitrary number of antennas with only limitation that the total number of users in the system has to be less than or equal to the rank of the combined multiple-input multiple-output (MIMO) channel matrix of all users. It was shown in the simulations that it extracts very high diversity gain and at low signal-to-noise ratios, when the total number of antennas at the user terminals is greater than the number of antennas at the base station, it approaches the maximum sum rate capacity of the broadcast channel. The technique introduced in this paper is favorable for practical implementation since it requires by an order of magnitude less operations than the techniques based on the singular value decomposition.
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Bawage, Sandeep Dhanraj, and Manjula Shivkumar. "Downlink channel analysis at multi-cell massive MIMO: novel adaptive channel allocation scheme." Bulletin of Electrical Engineering and Informatics 11, no. 3 (June 1, 2022): 1577–85. http://dx.doi.org/10.11591/eei.v11i3.3479.
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In large multiple-input multiple-output (MIMO) systems, we offer a new access strategy for crowd situations. Crowd situations include a high number users who have intermittent access patterns, making orthogonal scheduling impossible. In this paper, the work is driven by the massive MIMO problem at crowded environment. The pilot contamination problem is dependent on the protocol assumptions is observed in the system. We investigate a crowd situation in which the users number and their access behaviours make scheduling broadcasts impossible. The pilot assignment is time-slot randomized, but the data portion is repeated, allowing it to use successive-interference-cancellation across copies of comparable packets. In result analysis, the transmission of downlink to the user has shown with changing the number of users, fading effect, transmission power and the number of base station antennas.
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Gupta, Parul, Leeladhar Malviya, and S. V. Charhate. "5G multi-element/port antenna design for wireless applications:a review." International Journal of Microwave and Wireless Technologies 11, no. 9 (May 28, 2019): 918–38. http://dx.doi.org/10.1017/s1759078719000382.
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AbstractFifth generation (5G) is the current hot topic of the world's leading telecommunication companies. The compact designs of antennas made it possible for them to resonate at higher frequencies, thus to enable the devices to attain higher data rate as compared to 4G technology. Data rate of 5G technology for low mobility users is expected to be 50.0 Gbps and for high mobility users it is 5.0 Gbps. On the other hand, International telecommunication union's objective for 5G is 3 times more spectrally efficient thanlong-term evolution (LTE). The paper has carried out meticulous study over the impact of 5G antennas on the size of antenna, size/type of substrate, gain, efficiency, and isolation, etc. Also, different arrays andmultiple input multiple outputs (MIMOs) with patch antenna, magneto electric-dipole, microstrip grid array antenna, folded dipole, series-fed array, connected antenna array, MIMO are studied. The paper also includes the existing technology i.e 4G LTE and their isolation enhancement approaches. Many of the designs used the reflector plates to reduce the back lobe radiation problem in MIMO/array antennas to increase front-to-back ratio. The gain in 5G antennas can be increased by using balun, parasitic element as directors, multiple notch structures, three identical slot sub-arrays, etc. Mathematical equations of multi-element/port antennas are included to model the designed antennas. The beam steering is also included for the 5G technology in this paper.
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Hang, Juan, and Feng She. "User Scheduling in Multi-User MIMO Systems with Buffer Counting." Advanced Materials Research 461 (February 2012): 62–66. http://dx.doi.org/10.4028/www.scientific.net/amr.461.62.
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This paper studies the user scheduling in MIMO systems with queue control. We assume the data packets are buffered at the transmitter. By modeling the channel as a queuing system, the property of queue control is analyzed. Then, user scheduling algorithm with consideration of queue state and channel state together is also investigated. Simulation results show that queue control can achieve fairness and keep stability among users
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Lee, Ling, Chun-An Chen, Chiao-En Chen, and Yuan-Hao Huang. "Square-Root Generalized Eigenvalue Decomposition Processor for Leakage-Based Multi-User MIMO Precoding With Multi-Antenna Users." IEEE Transactions on Circuits and Systems I: Regular Papers 66, no. 6 (June 2019): 2382–93. http://dx.doi.org/10.1109/tcsi.2019.2893274.
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Rezaei, Fatemeh, and Aliakbar Tadaion. "Multi-layer beamforming in uplink/downlink massive MIMO Systems with multi-antenna users." Signal Processing 164 (November 2019): 58–66. http://dx.doi.org/10.1016/j.sigpro.2019.05.006.
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Li, Xin Min, Bao Ming Bai, and Juan Zhao. "SDR-Based Precoding for Multi-User Multi-Stream MIMO Downlinks." Applied Mechanics and Materials 543-547 (March 2014): 2004–8. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.2004.
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The existing methods based on convex-optimization theory, which use the concept of SINR, can just design the optimal precoder for each user with single antenna. In this paper, we design the optimal precoding matrices for multi-user MIMO downlinks by solving the optimization problem that minimizes total transmit power subject to signal-leakage-plus-noise-ratio (SLNR) constraints. Because SLNR of each user is determined by its own precoding matrix and is independent of other users, the goal problem can be separated into a series of decoupled low-complexity quadratically constrained quadratic programs (QCQPs). Using the semidefinite relaxation (SDR) technique, these QCQPs can be reformulated into the semidefinite programs (SDP) and be solved effectively. Simulation results show that proposed precoding scheme is quite feasible when each user has two receive antennas, and it has better bit error rate (BER) performance than the original maximal-SLNR precoding scheme when SLNR of each user satisfies large threshold value.
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Wang, Yan Wen, and Zhi Wei Yin. "A New Multi-User Beamforming Algorithm." Applied Mechanics and Materials 130-134 (October 2011): 3169–72. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.3169.
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In R9 version of LTE system, the double multi-user beamforming is proposed. To suppress inter-user interference of multi-user multiple input multiple output (MU-MIMO) system, a new algorithm is presented in this paper: on condition that current user eliminates the interference to other users, it designs its own transmit beamforming vector; if all users take such measures, the interference that each user suffers from others will be reduced to a minimum, which improves the performance of the system. Simulation shows that, as the number of user increases, the algorithm used in this paper can reduce the bit error rate (BER) of the system more obviously than the traditional signal-to-leakage-and-noise ratio (SLNR) algorithm.
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Sergeev, A. M., and N. Sh Blaunstein. "Evolution of multiple-access networks cellular and non-cellular — in historical perspective. Part 1." Information and Control Systems, no. 4 (September 23, 2018): 86–104. http://dx.doi.org/10.31799/1684-8853-2018-4-86-104.
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Introduction:The goal of this review is the analysis of evolution of the current and novel wireless networks, from secondgeneration (2D)tofifth generation(5G),as well as changes in technologies and their corresponding theoretical background andprotocols -from Bluetooth, WLAN, WiFi and WiMAXtoLTE, OFDM/OFDMA, MIMO and LTE/MIMO advanced technologies with new hierarchy of cellular maps design — femto/pico/micro/macro.Methods:We use new theoretical frameworkstodescribe advanced technologies, such as multicarrier diversity technique, OFDM and OFDM novel approach, new aspects ofMIMO description based on multi-beam antennas, design of various cellular maps based on new algorithms of femto/pico/micro/macrocell deployment, and the methodology of a new MIMO/LTE system integration based on multi-beam antennas.Results:We have created a new methodology for multi-carrier diversity description of novel multiple-access networks, forthe usage of OFDM/OFDMA modulation in ordertoovercome inter-user and inter-symbol interference in multiple-access networks, as well as multiplicative noises in multiple-access wireless networks caused by multi-ray phenomena. Finally, wehave suggested howtoovercome the propagation effects occurring in the terrestrial communication channels by using acombination of MIMO and LTE technologies based on multi-beam antennas. For these purposes, we present a new stochasticapproach which takes into account the terrain features, such as buildings' overlay profile, buildings' density around the base station and each user's antennas, andsoforth. These parameters allow ustoestimate the effects of fading as a multiplicativenoise source.Practical relevance:The new methodology of estimating the effects created by multiplicative noise and inter-user and inter-symbol interference in terrestrial wireless networks allows ustopredict a-priory practical aspects of the currentand new multiple-access wireless communication systems, like the potential number of users or the spectral efficiency ofuser channels for various configurations of cell deployment: femto, pico, micro, and macro, as well as the novel MIMO/LTE system configurations for future networks of the 4th and 5th generations.
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Madeira, João, João Guerreiro, Hugo Serra, Rui Dinis, Paulo Montezuma, and Luís Miguel Campos. "A Physical Layer Security Technique for NOMA Systems with MIMO SC-FDE Schemes." Electronics 9, no. 2 (February 1, 2020): 240. http://dx.doi.org/10.3390/electronics9020240.
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Current wireless communication systems employ Multi-Input, Multi-Output (MIMO) techniques to increase spectral efficiency, at the cost of higher hardware complexity. Most of these systems continue to employ traditional Orthogonal Multiple Access (OMA) schemes, which are suboptimal when compared to Non-Orthogonal Multiple Access (NOMA) schemes. By combining NOMA with MIMO, it is possible to achieve higher spectral efficiencies. However, security in NOMA-MIMO systems remains a problem. In this paper, we study the physical layer security issues of a power based NOMA-MIMO system with a Singular Value Decomposition (SVD) scheme, employed along with Single Carrier with Frequency Domain Equalization (SC-FDE) techniques. We consider a scenario where there is an unintended eavesdropper attempting to listen to the messages being exchanged. It is shown that the higher the channel estimate correlation between transmitter and receiver, the higher the secrecy rate, particularly for a scenario where there is a Line-Of-Sight (LOS) between all users. Therefore, power based NOMA MIMO-SVD schemes, combined with SC-FDE, can be considered efficient options for highly secure MIMO communications.
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Kalachikov, A., R. Bezgodkin, I. Petrov, and A. Vinnikov. "Performance Evaluation of the MU-MIMO Precoding Using the QuaDRiGa Channel Model." Proceedings of Telecommunication Universities 8, no. 1 (April 1, 2022): 41–47. http://dx.doi.org/10.31854/1813-324x-2022-8-1-41-47.
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The article presents the analysis of characteristics of algorithms of signal precoding in a multi-antenna system with many users (MU-MIMO). This paper presents the numerical evaluation of the multiuser MIMO beamforming algorithms ZF and DFT codebook based on a QUADRIGA channel model, taking into account the real conditions of signal propagation. The generated channels are used to calculate SINR and the spectral efficiency values of each user using the conventional ZF and DFT beamforming codebook. The eigenvalues of the MIMO channel are important in evaluating the MU-MIMO transmission performance characteristics, such as the spectral efficiency of a precoded system. The obtained performance of MU-MIMO ZF and DFT codebook-based beamforming in spatially correlated channels are compared based on the empirical cumulative density function of the sum rate of multiple users. Spatial correlation degrades capacity performance, and in the channels, the DFT precoder has a more robust performance and outperforms the ZF precoder in spectral efficiency. Obtained results can be used by the algorithm evaluation in the system-level simulations.
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Le, Mai Thi Phuong, Hung Le Nguyen, Hieu Van Nguyen, and Vien Duy Nhat Nguyen. "Spectral Efficiency Optimization for Full Duplex Multi-User MIMO Network." Journal of Science and Technology: Issue on Information and Communications Technology 18, no. 12.2 (December 29, 2020): 43. http://dx.doi.org/10.31130/ict-ud.2020.120.
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In this paper, we investigate the spectral efficiency (SE) of a multi-user multiple-input multiple-output (MU-MIMO) antenna network in full-duplex (FD) regime, where uplink (UL) and downlink (DL) users simultaneously share the same time and frequency resources. Zero-forcing approach is applied efficiently to precode/detect signals in both UL and DL. To achieve the SE maximization, we formulate an optimized problem where the transmit power of Base station (BS) and users are jointly considered. Numerical results are used to show that the proposed algorithm may bring significant SE gain over the previous approaches under realistic channel conditions.
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Kim, Yunesung, Guowang Miao, and Taewon Hwang. "Energy Efficient Pilot and Link Adaptation for Mobile Users in TDD Multi-User MIMO Systems." IEEE Transactions on Wireless Communications 13, no. 1 (January 2014): 382–93. http://dx.doi.org/10.1109/twc.2013.120113.130677.
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Sergeev, A. M., and N. Sh Blaunstein. "Evolution of multiple-access networks - cellular and non-cellular - in historical perspective. Part 3." Information and Control Systems, no. 6 (December 18, 2018): 82–94. http://dx.doi.org/10.31799/1684-8853-2018-6-82-94.
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Introduction:The goal of this issue is the analysis of evolution of the current and novel wireless networks, from second generation (2D) to fifth generation (5G), as well as changes in technologies and their corresponding theoretical background and protocols — from Bluetooth, WLAN, WiFi and WiMAX to LTE, OFDM/OFDMA, MIMO and LTE/MIMO advanced technologies with new hierarchy of cellular maps design — femto/plco/mlcro/macro.Methods:We use new theoretical frameworks for description of the advanced technologies, such as multicarrier diversity technique, OFDM and OFDM novel approach, MIMO aspects description based on multi-beam antennas approach, various cellular maps design based on a new algorithms offemto/pico/micro/macrocell deployment, and a new methodology of a new MIMO/LTEsystem integration based on multi-beam antennas.Results:We have created a new methodology of multi-carrier diversity description for novel multiple-access networks, of usage of OFDM/OFDMA modulation to obey inter-user and inter-symbol interference in multiple-access networks, of how to obey the multiplicative noises occurring in the multiple-access wireless networks, caused by multi-ray phenomena, and finally, of how to overcome propagation effects occurring in the terrestrial communication links by use combination of MIMO and LTE technologies based on multi-beam antennas. For these purposes we present new stochastic approach that accounts for the terrain features, such as buildings' overlay profile, buildings' density around the base station and each user antennas, and so forth. These parameters allow us to estimate for each situation occurs at the built-up terrain area the effects of fading, as a source of multiplicative noise.Practical relevance:New methodology of how to estimate effects of multiplicative noise, inter-user and inter-symbol interference, occurring in the terrestrial wireless networks, allows us to predict a-priory practical aspects of the current and new multiple-access wireless communication networks, such as: the users' capacity and user's links spectral efficiency for various configurations of cells deployment — femto, pico, micro, and macro, as well as the novel MIMO/LTEsystem configuration for future networks of 4thand 5thgeneration deployment.
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Jang, Youngsu, Honggu Kang, Minho Park, Jeung Won Choi, and Joonhyuk Kang. "Analysis on Secondary User Receiver SINR in Spectrum Sharing MIMO Cognitive Radio Networks with Multi Secondary Users." Journal of Korean Institute of Communications and Information Sciences 44, no. 2 (February 28, 2019): 252–61. http://dx.doi.org/10.7840/kics.2019.44.2.252.
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Kai, Tao, Sun Xiaoyun, Wang Yang, and Jingchun Li. "System Modeling and Precoding Design for Multi-beam Dual-polarized Satellite MIMO System." Recent Patents on Engineering 13, no. 4 (December 27, 2019): 374–81. http://dx.doi.org/10.2174/1872212112666181015150356.
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Background: As the multimedia service develops and the transmission rate in terrestrial communication systems increases rapidly, satellite communication needs to improve the transmission rate and throughput. Multiple Input Multiple Output (MIMO) techniques can increase the system capacity significantly by introducing the space dimension, as the system bandwidth remains the same. Therefore, utilization of MIMO for satellite communications to increase the capacity is an important research topic. So MIMO techniques for multibeam satellite communications are researched in the dissertation. Objective: The goal of this work is improving the capacity of the satellite system. Multi-beam and dual-polarized technologies are applied to a satellite system to improve the capacity further. Methods: In this paper, we first introduce a multi-beam dual-polarized satellite multi-put and multiout (MBDP-S-MIMO) system which combines the full frequency multiplexing and dual-polarization technologies. Then the system model and channel model are first constructed. At last, to improve the capacity further, BD and BD-ZF precoding algorithms are applied to MBDP-S-MIMO and their performance is verified by simulation. Results: Simulation results show the performance of the BD precoding algorithm gets better with the growth of the XPD at the receiver and is almost not affected by the growth of the channel polarization correlation coefficient. In addition, with the growth of the users’ speed, the performance becomes worse. Conclusion: The multi-beam dual-polarized satellite MIMO system has high capacity, and it has certain application prospects for satellite communication.
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Viana, Joseanne, Francisco Cercas, Américo Correia, Rui Dinis, and Pedro Sebastião. "MIMO Relaying UAVs Operating in Public Safety Scenarios." Drones 5, no. 2 (April 26, 2021): 32. http://dx.doi.org/10.3390/drones5020032.
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Methods to implement communication in natural and humanmade disasters have been widely discussed in the scientific community. Scientists believe that unmanned aerial vehicles (UAVs) relays will play a critical role in 5G public safety communications (PSC) due to their technical superiority. They have several significant advantages: a high degree of mobility, flexibility, exceptional line of sight, and real-time adaptative planning. For instance, cell edge coverage could be extended using relay UAVs. This paper summarizes the sidelink evolution in the 3GPP standardization associated with the usage of the device to device (D2D) techniques that use long term evolution (LTE) communication systems, potential extensions for 5G, and a study on the impact of circular mobility on relay UAVs using the software network simulator 3 (NS3). In this simulation, the transmitted packet percentage was evaluated where the speed of the UAV for users was changed. This paper also examines the multi-input multi-output (MIMO) communication applied to drones and proposes a new trajectory to assist users experiencing unfortunate circumstances. The overall communication is highly dependent on the drone speed and the use of MIMO and suitable antennas may influence overall transmission between users and the UAVs relay. When the UAVs relaying speed was configured at 108 km/h the total transmission rate was reduced to 55% in the group with 6 users allocated to each drone.
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Lee, Woon-Sang, Jae-Hyun Ro, Young-Hwan You, Duckdong Hwang, and Hyoung-Kyu Song. "An Enhanced Precoder for Multi User Multiple-Input Multiple-Output Downlink Systems." Applied Sciences 10, no. 13 (June 30, 2020): 4547. http://dx.doi.org/10.3390/app10134547.
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Recently, as the demand for data rate of users has increased, wireless communication systems have aimed to offer high throughput. For this reason, various techniques which guarantee high performance have been invented, such as massive multiple-input multiple-output (MIMO). However, the implementation of huge base station (BS) antenna array and decrease of reliability as the number of users increases are chief obstacles. In order to mitigate these problems, this paper proposes an adaptive precoder which provides high throughput and bit error rate (BER) performances to achieve the desired data rate in multi user (MU) MIMO downlink systems which have a practical BS antenna array (up to 16). The proposed scheme is optimized with a modified minimum mean square error (MMSE) criterion in order to improve BER gain and reduce data streams in order to obtain diversity gain at low signal to noise ratio (SNR). It is shown that the BER and throughput performances of the proposed scheme are improved.
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Yu, Seoyoung, and Jeong Woo Lee. "Channel Sounding for Multi-User Massive MIMO in Distributed Antenna System Environment." Electronics 8, no. 1 (January 1, 2019): 36. http://dx.doi.org/10.3390/electronics8010036.
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We propose a generation scheme for a sounding reference signal (SRS) suitable for supporting a large number of users in massive multi-input multi-output (MIMO) system with a distributed antenna system (DAS) environment. The proposed SRS can alleviate the pilot contamination problem which occurs inherently in the multi-user system due to the limited number of orthogonal sequences. The proposed SRS sequence is generated by applying a well-chosen phase rotation to the conventional LTE/LTE-A SRS sequences without requiring an increased amount of resource usage. We also propose using the correlation-aided channel estimation algorithm as a supplemental scheme to obtain more reliable and refined channel estimation. It is shown that the proposed SRS sequence and the supplemental channel estimation scheme improve significantly the channel estimation performance in multi-user massive MIMO systems.
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Hakimi, Walid, and Ammar Mahmoud. "Performance Evaluation of Space-Time and Harq Diversity in MIMO HSDPA." International Journal of Mobile Computing and Multimedia Communications 4, no. 3 (July 2012): 71–86. http://dx.doi.org/10.4018/jmcmc.2012070105.
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Multi-antenna techniques can be used to achieve improved system performance, including improved system capacity (more users per cell) and improved coverage (possibility for larger cells), as well as improved service provisioning, for example, higher per-user data rates. This study provides an overview of space-time diversity technique using Alamouti codes applied to the 3G evolution. The delays introduced by HARQ retransmission decrease the performance of the HSDPA system. Multi-antenna techniques are specifically applied to HSDPA to avoid HARQ retransmissions. The authors demonstrate that space-time Rake detector in MIMO 2x2 based on Alamouti code without HARQ process could give better performances than MIMO 2x1 taking into account the HARQ context. In the case of MIMO 2x2,they also observed that the limit of retransmissions affects the system performance and efficiency. Using the generalized Alamouti coding technique in MIMO 4x4 with Multipath Parallel Interference Canceller (MPIC) detector, we achieve notable improvement of performance under the same channel and signal to-Noise Ratio (SNR) conditions.
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Madeira, João, João Guerreiro, Rui Dinis, Paulo Montezuma, and Luís Miguel Campos. "On the Physical Layer Security Characteristics for MIMO-SVD Techniques for SC-FDE Schemes." Sensors 19, no. 21 (November 1, 2019): 4757. http://dx.doi.org/10.3390/s19214757.
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Multi-Input, Multi-Output (MIMO) techniques are seeing widespread usage in wireless communication systems due to their large capacity gains. On the other hand, security is a concern of any wireless system, which can make schemes that implement physical layer security key in assuring secure communications. In this paper, we study the physical layer security issues of MIMO with Singular Value Decomposition (SVD) schemes, employed along with Single-Carrier with Frequency-Domain Equalization (SC-FDE) techniques. More concretely. the security potential against an unintended eavesdropper is analysed, and it is shown that the higher the distance between the eavesdropper and the transmitter or receiver, the higher the secrecy rate. In addition, in a scenario where there is Line of Sight (LOS) between all users, it is shown that the secrecy rate can be even higher than in the previous scenario. Therefore, MIMO-SVD schemes combined with SC-FDE can be an efficient option for highly secure MIMO communications.
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Trifan, Razvan-Florentin, Andrei-Alexandru Enescu, and Constantin Paleologu. "Hybrid MU-MIMO Precoding Based on K-Means User Clustering." Algorithms 12, no. 7 (July 23, 2019): 146. http://dx.doi.org/10.3390/a12070146.
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Multi-User (MU) Multiple-Input-Multiple-Output (MIMO) systems have been extensively investigated over the last few years from both theoretical and practical perspectives. The low complexity Linear Precoding (LP) schemes for MU-MIMO are already deployed in Long-Term Evolution (LTE) networks; however, they do not work well for users with strongly-correlated channels. Alternatives to those schemes, like Non-Linear Precoding (NLP), and hybrid precoding schemes were proposed in the standardization phase for the Third-Generation Partnership Project (3GPP) 5G New Radio (NR). NLP schemes have better performance, but their complexity is prohibitively high. Hybrid schemes, which combine LP schemes to serve users with separable channels and NLP schemes for users with strongly-correlated channels, can help reduce the computational burden, while limiting the performance degradation. Finding the optimum set of users that can be co-scheduled through LP schemes could require an exhaustive search and, thus, may not be affordable for practical systems. The purpose of this paper is to present a new semi-orthogonal user selection algorithm based on the statistical K-means clustering and to assess its performance in MU-MIMO systems employing hybrid precoding schemes.
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Chopra, Shakti Raj, Akhil Gupta, Sudeep Tanwar, Calin Ovidiu Safirescu, Traian Candin Mihaltan, and Ravi Sharma. "Multi-User Massive MIMO System with Adaptive Antenna Grouping for Beyond 5G Communication Network." Mathematics 10, no. 19 (October 3, 2022): 3621. http://dx.doi.org/10.3390/math10193621.
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Error-correcting codes with limited errors and higher spectral efficiency are the main concern for wireless communications. In the current situation, research is increasing daily to satisfy the growing demand for users with improved QoS. Adaptive Antenna Grouping (AAG) with a multilevel space–time trellis coding scheme in the Multi-User Massive MIMO system is the better option to provide flexible data transfer speeds, encoding gains, and gain in diversity with improved spectral efficiency and low decoding complexity, including the power optimization by reduced SNR at the same Symbol Error Rate/Frame Error Rate (SER/FER). The prior aim of maintaining spectral efficiency is achieved by using Massive MIMO. This paper presents the AAG according to the channel state information in the Massive MIMO scenario. The impact of the proposed model on standard ITU-R M.2135 scenarios is also demonstrated in this paper.
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Mancharla, Ravi, and Yaka Bulo. "A Comparative Analysis of the various Power Allocation Algorithm in NOMA-MIMO Network Using DNN and DLS Algorithm." ICST Transactions on Mobile Communications and Applications 7, no. 2 (August 31, 2022): e3. http://dx.doi.org/10.4108/eetmca.v7i2.2651.
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The high data rate, huge spectrum efficiency, successive interference cancellation (SIC), and ultra-reliable low latency (URLL) are of the demand for next-generation technologies. Non-orthogonal multiple access (NOMA) scheme provides multi-user scaling (multiplexing), optimum spectral efficiency (SE), excellent user-pairing improvement, and a single resource block sharing by multiple users because of which it is a more preferable scheme over orthogonal multiple access (OMA) for the next generation technologies. This article investigates comparative analysis of various power allocation algorithms in multiple-input multiple-output-NOMA (MIMO-NOMA) technology and to come up with the best power allocation algorithm which suited best for MIMO-NOMA technology. Firstly, comparison analysis will be carried out considering direct methodologies followed by power allocation algorithm using Deep Neural Network (DNN) along with the Depth limited search (DLS) algorithm. These techniques are tested on two users initially then followed by multi-user communication. Allocating optimal power to the poor signal strength user terminal (user not receiving appropriate signal power) is a difficult task in actual scenario, and moreover, SIC also creates complexity in the proper allocation of Base station (BS) source power. The above problems can be solved with the assistance of the DNN along with the DLS algorithm, where the weaker user receives maximum power and the stronger user receives minimum power. The DNN-MIMO-NOMA technology, which is based on the DLS algorithm, helps user terminals to get their signals free from noise (inter_user_interference) and with greater precision. The DLS process (algorithm) offers higher potential in MIMO-NOMA with DNN technology for successfully applying SIC. Here, MIMO helps to improve the channel gain. A DLS provides an optimum power allocation (OPA) based on the position of user equipment. The simulation results show that the power allocation method using DNN along with DLS algorithm achieves better performance than the traditional multi-user.
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Panta, Jariya, Poompat Saengudomlert, and Karel L. Sterckx. "Efficient User Grouping for MU-MIMO Visible Light Communications Based on Block Diagonalization." ECTI Transactions on Electrical Engineering, Electronics, and Communications 20, no. 3 (October 15, 2022): 329–38. http://dx.doi.org/10.37936/ecti-eec.2022203.247510.
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This paper investigates efficient user grouping methods for multi-user multi-input multi-output (MU-MIMO) visible light communication (VLC) systems. Block diagonalization (BD) precoding is considered for interference avoidance. In addition, time division multiplexing (TDM) is applied to perform user grouping when the number of users exceeds the limit of BD precoding based on the number of light emitting diode (LED) transmitters and the total number of users' photodiodes (PDs). User grouping methods are proposed based on pairwise interference considerations among users in the same group. The proposed methods can be implemented through integer linear programming (ILP), which requires less computation than exhaustive search. The numerical results on the average minimum user throughputs over random scenarios indicate that the proposed hybrid method can significantly outperform random user grouping and performs reasonably well compared to exhaustive search. Finally, this study demonstrates that, when BD precoding greatly attenuates the desired user signals, user grouping can help improve minimum user throughputs even though BD precoding can support all users as a single group.
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Hemrungrote, Sirichai, Toshikazu Hori, Mitoshi Fujimoto, and Kentaro Nishimori. "Channel Capacity Evaluation for Urban MIMO Systems Using Path Visibility." ECTI Transactions on Electrical Engineering, Electronics, and Communications 9, no. 1 (July 9, 2010): 121–32. http://dx.doi.org/10.37936/ecti-eec.201191.172335.
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Multiple-Input Multiple-Output (MIMO) and Multi-User MIMO (MU-MIMO) systems are expected to improve the channel capacity over the limited bandwidth of existing wireless communication networks. The effects on the channel capacity characteristics of Single-User MIMO (SU-MIMO) systems in urban scenarios have been previously studied. In this paper, we first clarify that the larger number of antennas cannot contribute the improvement in the channel capacity in urban SU-MIMO scenarios due to the very high spatial correlation. Next, we focus on the MU-MIMO transmission because it can discriminate multiple users by the difference of Angle of Arrival (AOA). We compare the Multi Access Channel (MAC) capacity in the uplink to the capacity in SU-MIMO by considering the same total numbers of transmitting and receiving antennas between SU-MIMO and MU-MIMO. When the same numbers of the antenna elements are used, the better performance is obtained by urban MU-MIMO systems, unlike in the identical independent distributed (iid) scenarios which are generally assumed in MIMO transmission. Finally, the parameter called path visibility introduced in our previous study is playing an important role once again. It is de¯ned as the probability that the direct wave can be received at the receiving antenna and has been used to determine the channel capacity characteristics and provide guidance in determining the appropriate range for the base station (BS) installation in urban SU-MIMO scenarios. In this study, we clarify that only this single parameter, path visibility, can also be used to determine the improvement in the channel capacity by MU-MIMO in urban scenarios, while both of SNR and spatial correlation must be considered as the indicative parameters on the performance of SU/MU-MIMO in conventional studies.
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He, Junyi, Junnan Zhang, Cheng Song, and Mengxiang Wu. "Spectral Efficiency of the Multiway Massive System over Rician Fading Channels." Security and Communication Networks 2021 (February 24, 2021): 1–8. http://dx.doi.org/10.1155/2021/6618363.
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In this study, we consider a multiway massive multi-input multi-output (MIMO) relay network over Rician fading channels, where all users intend to share their information with the other users via amplify-and-forward (AF) relays equipped with a great number of antennas. More practical, the imperfect channel state information (CSI) is taken into account. To evaluate the performance of the considered networks, we derived an analytical approximation expression for the spectral efficiency with zero-forcing (ZF) receivers in a closed form. To obtain more insights, the asymptotic analysis as the number of relay antenna approaching infinity is carried out. Finally, the power scaling law is analyzed for two scenarios. The results reveal that (1) massive MIMO is capable of compensating the loss caused by Rician fading, (2) the sum spectral efficiency increases with the increase of the Rician factor, and (3) deploying large-scale antenna is effective to save cost and keep performance.
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Khomyat, Tanapong, Peerapong Uthansakul, and Monthippa Uthansakul. "Performance Analysis of MU-MIMO Systems Using HMRS Technique for Various Transmission Modes." ECTI Transactions on Electrical Engineering, Electronics, and Communications 12, no. 1 (February 25, 2014): 53–62. http://dx.doi.org/10.37936/ecti-eec.2014121.170804.
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It is the fact that the bandwidth of wireless communication system is such a limited resource that several techniques are selectively applied to increase the bandwidth efficiency. The highest bandwidth efficiency can be taken by applying Multi-User Multiple-Input Multiple-Output (MU-MIMO) technique. For this technique, the complexity of detection is rapidly increased by increasing the number of users. Thus the lower complex detection is necessarily required for MU-MIMO system. Recently, the simple detection technique called hybrid-MIMO receiver scheme (HMRS) has been proposed by the authors. However, that study neglected the demands of multiple users for transmitting MIMO modes which are crucially unpredictable in practice. In this paper, the performance analysis of MU-MIMO system using HMRS technique to support various types of user transmission modes is presented. Moreover, the nearly exact symbol error rate (SER) analysis of HMRS with the nonlinear error propagation effect over Rayleigh channels is originally presented. The recursive procedure is adopted to derive the nearly closed-form expressions of the error probability of each user. The results indicate that HMRS technique can improve the error rate more than the existing hybrid-MIMO about 8 dB at 10e−4 SER, increasing the total number of user and number of SM user introduce the diversity gain loss. The simulation results illustrate the performance accuracy of the proposed analysis.
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He, Shibiao, Jieru Du, and Yong Liao. "Multi-User Scheduling for 6G V2X Ultra-Massive MIMO System." Sensors 21, no. 20 (October 11, 2021): 6742. http://dx.doi.org/10.3390/s21206742.
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6G vehicle-to-everything (V2X) communication will be combined with vehicle automatic driving technology and play an important role in automatic driving. However, in 6G V2X systems, vehicle users have the characteristics of high-speed movement. Therefore, how to provide stable and reliable wireless link quality and improve channel gain has become a problem that must be solved. To solve this problem, a new multi-user scheduling algorithm based on block diagonalization (BD) precoding for 6G ultra-massive multiple-input multiple-output (MIMO) systems is proposed in this paper. The algorithm takes advantage of the sensitive nature of BD precoding to channel correlation, uses the Pearson coefficient after matrix vectorization to measure the channel correlation between users, defines the scheduling factor to measure the channel quality according to the user noise enhancement factor, and jointly considers the influence of the correlation between user channels and channel quality, ensuring the selection of high-quality channels while minimizing channel correlation. Simulation results show that compared with the multi-user scheduling algorithm based on subspace correlation, condition number, and geometric angle, the proposed algorithm can obtain higher user channel gain, effectively reduce the system bit error rate, and can be applied to 6G V2X communication.
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Wang, Yan Li. "Interference Suppression Detection Algorithms in STBC-MIMO Systems." Applied Mechanics and Materials 130-134 (October 2011): 2940–43. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.2940.
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Aiming at the uplink multi-user STBC-MIMO system, we adopted the combination of the detection scheme about the linear MMSE interference suppression and symbol estimation, and the receiver maintained decoding simplicity. Theory analysis and simulation results reveal that the proposed scheme can suppress and cancel the interference from co-channel users effectively without increasing the complexity significantly.
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Dou, Jian, Xuan Liu, Shuang Qie, Jiayi Li, and Chaoliang Wang. "Spectrum Allocation and User Scheduling Based on Combinatorial Multi-Armed Bandit for 5G Massive MIMO." Sensors 23, no. 17 (August 29, 2023): 7512. http://dx.doi.org/10.3390/s23177512.
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As a key 5G technology, massive multiple-input multiple-output (MIMO) can effectively improve system capacity and reduce latency. This paper proposes a user scheduling and spectrum allocation method based on combinatorial multi-armed bandit (CMAB) for a massive MIMO system. Compared with traditional methods, the proposed CMAB-based method can avoid channel estimation for all users, significantly reduce pilot overhead, and improve spectral efficiency. Specifically, the proposed method is a two-stage method; in the first stage, we transform the user scheduling problem into a CMAB problem, with each user being referred to as a base arm and the energy of the channel being considered a reward. A linear upper confidence bound (UCB) arm selection algorithm is proposed. It is proved that the proposed user scheduling algorithm experiences logarithmic regret over time. In the second stage, by grouping the statistical channel state information (CSI), such that the statistical CSI of the users in the angular domain in different groups is approximately orthogonal, we are able to select one user in each group and allocate a subcarrier to the selected users, so that the channels of users on each subcarrier are approximately orthogonal, which can reduce the inter-user interference and improve the spectral efficiency. The simulation results validate that the proposed method has a high spectral efficiency.
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Eiji, Arta, and Silpha Mehta. "Simulation-Based 5G Femtocell Network System Performance Analysis." International Journal of Cyber and IT Service Management 3, no. 1 (March 29, 2023): 74–78. http://dx.doi.org/10.34306/ijcitsm.v3i1.127.
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The field of telecommunications technology has undergone significant changes in recent years, particularly with the development and commercial use of 4G and 5G technologies. As 5G technology becomes increasingly prevalent in Indonesia, it is important to explore the ideal network configurations that can achieve desired data rates in areas with high user densities. This study focuses on femtocell networks, which are compact base stations that require minimal power and are ideal for indoor use. Specifically, the study examines three alternative MIMO antenna scenarios, which are Multi-Input Multi-Output antenna designs that can improve data throughput. The study's simulation results indicate that a 16X16 MIMO design offers the best performance in achieving data rates of 1Gbps for all users in a high-density site. This design outperforms 4X4 and 8X8 MIMO arrangements in terms of data throughput, making it the ideal network configuration for femtocell networks in areas with high user densities. The findings of this study can be applied to the deployment and optimization of femtocell networks, which can improve network capacity and data rates for users in indoor environments. As 5G technology continues to advance, the findings of this study will be increasingly relevant and useful for optimizing network configurations and achieving desired data rates.
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Gao, Xian Kun, Jian Hua Qu, Chuan An Yao, and Yong Chang Yu. "A Successive Iterative Optimal Pre-Coding Algorithm for Downlink Multi-User MIMO System." Advanced Materials Research 457-458 (January 2012): 1012–18. http://dx.doi.org/10.4028/www.scientific.net/amr.457-458.1012.
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Spatial multiplexing in the multi-user MIMO downlink allows each user in the system to receive multiple data subchannels simultaneously using the same time and spectral resources. In this paper, a successive iterative optimal algorithm based on signal-to-leakage-and-noise-ratio (SLNR) maximization algorithm is proposed, which make use of the unused subspace of some known users to improve the space gain of the other users and has no strict constraint on transmit and receive antennas numbers. According to the simulation results, the proposed algorithm outperforms the original SLNR algorithm, and has a considerable improvement in the system performance.
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Lv, Ming Xia, Yan Kun Lai, and Dong Tang. "Performance Analysis of Low Complexity Multiuser Scheduling Algorithms in MIMO System." Applied Mechanics and Materials 392 (September 2013): 867–71. http://dx.doi.org/10.4028/www.scientific.net/amm.392.867.
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The total throughput of the communication system can be maximized by allocating the common radio resource to the user or the user group having the best channel quality at a given time and the multiuser diversity gain can be obtained when multiple users share the same channel at one time. The object to select the users is to select the users with the maximum sum capacity. As for a scheduling algorithm, exhaustive algorithm can get the largest capability of the system by multi-user scheduling. However, this algorithm is quite complex hence the cost of operation to a base station has substantial increased. We compare the multiuser performance of two fast user selection algorithms with low complexity in MIMO-MRC systems with co-channel interferences. From the simulation results, these two algorithms not only decrease the computational complexity of the scheduling algorithm but also retain large capability of the MIMO system.
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Li, Xiao Wu. "A Novel User Selection Algorithm for Multiuser MIMO-OFDMA System with Zero-Forcing Beamforming." Applied Mechanics and Materials 198-199 (September 2012): 1442–46. http://dx.doi.org/10.4028/www.scientific.net/amm.198-199.1442.
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As an important pre-coding method in MIMO- OFDMA system, zero-forcing beamforming (ZFBF) can eliminate co-channel interference (CCI) between users, and generate a series of parallel spatial subchannel without interference. In this paper, we propose a novel ZFBF-based user scheduling algorithm for multi-user downlink MIMO-OFDMA systems. The algorithm can satisfy the rate requirement of each user, choose the right user set in each subcarrier and minimize the total transmit power. Simulation results show that the proposed algorithm does outperform the non-adaptive algorithm and SUS-algorithm.
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Al-hubaishi, Ahmed S., Nor Kamariah Noordin, Aduwati Sali, Shamala Subramaniam, Ali Mohammed Mansoor, and Safwan M. Ghaleb. "Partial Pilot Allocation Scheme in Multi-Cell Massive MIMO Systems for Pilot Contamination Reduction." Energies 13, no. 12 (June 18, 2020): 3163. http://dx.doi.org/10.3390/en13123163.
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Inter-cell interference has been identified as one of the major challenges of multiple-input–multiple-output (MIMO)-enabled cellular systems. This problem occurs when the same pilot sets are reused across adjacent cells to save bandwidth for data transmission. As a result, so-called pilot contamination occurs, which cannot be mitigated with an increased number of serving antennas. In this work, we proposed a partial pilot allocation scheme (PPA) to tackle the pilot contamination problem and consequently improve the uplink throughput of users in multi-cell massive MIMO systems. This was achieved by using the large-scale characteristics of the fading channel to keep users with a weak channel condition out of the effect of severe interference during the pilot allocation process. Simulation results showed that the proposed scheme outperformed both smart pilot allocation (SPA) and conventional schemes. In particular, PPA improved the uplink rate by 30% compared to the SPA—a recently proposed schema. Furthermore, our simulation results clearly showed that PPA improved the cumulative distribution function (CDF) of the signal-to-interference-plus-noise ratio (SINR) and uplink throughput.
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Seyman, Muhammet Nuri, and Bircan Demiral. "An efficient approach for sub-carrier allocation in MIMO MC-CDMA systems." Journal of Electrical Engineering 73, no. 3 (June 1, 2022): 221–25. http://dx.doi.org/10.2478/jee-2022-0030.
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Abstract Sub-carrier allocation is an important process that directly affects users data and bit error rates for multi-user multi-carrier systems. The most important feature of the allocation process is to assign the sub-carriers to the active users in proportion to their needs to provide high-speed data transmission and reduce the bit error rates. In this study, an efficient subcarrier allocation algorithm has been proposed based on both capacity and fairness criteria for a MIMO MC-CDMA system, which is preferred as the multiplexing scheme in high data rate communication systems. The proposed algorithm achieves not only better error rate performance but also increases the total data rate compared to other algorithms
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Csathó, Botond Tamás, Bálint Péter Horváth, and Péter Horváth. "Modeling the near-field of extremely large aperture arrays in massive MIMO systems." Infocommunications journal 12, no. 3 (2020): 39–46. http://dx.doi.org/10.36244/icj.2020.3.6.
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Massive multiple-input multiple-output (MIMO) is a key technology in modern cellular wireless communication systems to attain a very high system throughput in a dynamic multi-user environment. Massive MIMO relies on deploying base stations equipped with a large number of antenna elements. One possible way to deploy base stations equipped with hundreds or thousands of antennas is creating extremely large aperture arrays. In this paper, we investigate channel modeling aspects of massive MIMO systems with large aperture arrays, in which many users are located in the near-field of the aperture. Oneand two-dimensional antenna geometries, different propagation models, and antenna element patterns are compared in terms of inter-user correlation, condition number of the multi-user channel matrix, and spectral efficiency to identify key design parameters and essential modeling assumptions. As our analysis reveals by choosing spectral-efficiency as a design objective, the size of the aperture is the critical design parameter.
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Zhao, Feng, Wen Wang, and Hongbin Chen. "Interference Alignment and Fairness Algorithms for MIMO Cognitive Radio Systems." Mobile Information Systems 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/907142.
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Interference alignment (IA) is an effective technique to eliminate the interference among wireless nodes. In a multiinput multi-output (MIMO) cognitive radio system, multiple secondary users can coexist with the primary user without generating any interference by using the IA technology. However, few works have considered the fairness of secondary users. In this paper, not only is the interference eliminated by IA, but also the fairness of secondary users is considered by two kinds of algorithms. Without losing generality, one primary user andKsecondary users are considered in the network. Assuming perfect channel knowledge at the primary user, the interference from secondary users to the primary user is aligned into the unused spatial dimension which is obtained by water-filling among primary user. Also, the interference between secondary users can be eliminated by a modified maximum signal-to-interference-plus-noise algorithm using channel reciprocity. In addition, two kinds of fairness algorithms, max-min fairness and proportional fairness, among secondary users are proposed. Simulation results show the effectiveness of the proposed algorithms in terms of suppressed interference and fairness of secondary nodes. What is more, the performances of the two fairness algorithms are compared.
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Chen, Xiaomin, Taotao Zhao, Qiang Sun, Qiaosheng Hu, and Miaomiao Xu. "Cell-Free Massive MIMO with Energy-Efficient Downlink Operation in Industrial IoT." Mathematics 10, no. 10 (May 14, 2022): 1687. http://dx.doi.org/10.3390/math10101687.
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Cell-free massive Multi-input Multi-output (MIMO) can offer higher spectral efficiency compared with cellular massive MIMO by providing services to users through the collaboration of distributed APs, and cell-free massive MIMO systems with distributed operations are attracting a great deal of industry attention due to their simplicity and ease of deployment. This paper aims to find an optimal solution for energy efficiency in the downlink operation in the Industrial Internet based on cell-free massive MIMO systems with distributed operations. A system model is proposed, and a theoretical analysis on energy efficiency is presented. The optimization problem of efficient downlink operation is formulated as a mixed-integer nonlinear programming (MINLP) problem, which is further decomposed into two sub-problems, i.e., maximizing the sum-rate of the downlink transmission and optimizing the total energy consumption. The two sub-problems are addressed via AP selection and power allocation, respectively. The simulation results demonstrate that our algorithms can significantly improve the energy efficiency with low computational complexity in comparison with traditional distributed cell-free massive MIMO. Even in the presence of pilot contamination, the proposed algorithms can still provide significant energy efficiency when a large number of IoTDs are connected.
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Zhao, Li Guo, and Wen Fan. "Studying on Multiple Services Precoding of MIMO System." Advanced Materials Research 328-330 (September 2011): 1684–88. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.1684.
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Multiple antennas at the transmitter and receiver have the potential to either increase data through spatial multiplexing or enhance the quality of transmission through exploitation of diversity. In this paper, based on studying proceeding of MIMO system, we propose a multi-service preceding algorithm. It makes sure different kinds of service have different SINR due to power allocation. The complex problem is decomposed into two separate steps. First, we achieve transmit vector for each user according SLNR to suppress CCI and noise. Then, we allocate the transmit power for users to satisfy SINR at receive end. Numerical simulation illustrates the effectiveness and support the use of multiple services in maximizing data rate and fairness among users.