Journal articles: 'MU precoding'

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Ibrahim, Sarmad Khaleel, and Saif A. Abdulhussien. "Performance evaluation of precoding system for massive multiple-input multiple-output." Bulletin of Electrical Engineering and Informatics 11, no. 4 (August 1, 2022): 2054–61. http://dx.doi.org/10.11591/eei.v11i4.3877.

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Low latency, high data speeds, and a higher degree of perceived service quality for consumers and base station capacity are only some of the advantages of fifth generation (5G) mobile communications. This paper focuses on the design of a precoding system for downlink transmission of multi-user multiple-input multiple-output (MU-MIMO). For MU-MIMO systems, the traditional precoding techniques investigated are difficult since the transmitter precoding matrices created by singular value decomposition (SVD) are calculated twice. This paper implements different techniques of precoding with channel coding. Two advanced precoding, zero forcing (ZF) and maximum ratio transmitter (MRT) systems will be evaluated to find the best between them. Three different coding channels (turbo, low-density parity-check (LDPC), and polar) are used in this paper. The results indicate that the ZF-MU-MIMO with turbo coding outperforms MRT precoding, and more spatial diversity gain may be gained, in terms of throughput, number of users supported, and lower error rate in downlink and uplink massive MIMO.

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He, Yujiao, Jianing Zhao, Lijuan Tao, Fuyu Hou, and Wei Jia. "Improved Port Modulation for Multiuser Massive MIMO Systems." International Journal of Interdisciplinary Telecommunications and Networking 7, no. 4 (October 2015): 15–25. http://dx.doi.org/10.4018/ijitn.2015100102.

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This paper proposes an improved port modulation (PM) method which can be applied to the multiuser (MU) massive multiple-input multiple-output (MIMO) system. The precoding process of the improved PM can be divided into two parts: port precoding and MU precoding. The methods of the precoding and detection are provided and the performance of the proposed improved PM is simulated and analyzed. Simulation results show that the proposed improved PM system can achieve a satisfying bit error rate (BER) performance with a cutdown channel state information (CSI) feedback.

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Liang, Rui, Hui Li, Yingli Dong, and Guodong Xue. "Efficient Constant Envelope Precoding for Massive MU-MIMO Downlink via Majorization-Minimization Method." Entropy 26, no. 4 (April 21, 2024): 349. http://dx.doi.org/10.3390/e26040349.

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The practical implementation of massive multi-user multi-input–multi-output (MU-MIMO) downlink communication systems power amplifiers that are energy efficient; otherwise, the power consumption of the base station (BS) will be prohibitive. Constant envelope (CE) precoding is gaining increasing interest for its capability to utilize low-cost, high-efficiency nonlinear radio frequency amplifiers. Our work focuses on the topic of CE precoding in massive MU-MIMO systems and presents an efficient CE precoding algorithm. This algorithm uses an alternating minimization (AltMin) framework to optimize the CE precoded signal and precoding factor, aiming to minimize the difference between the received signal and the transmit symbol. For the optimization of the CE precoded signal, we provide a powerful approach that integrates the majorization-minimization (MM) method and the fast iterative shrinkage-thresholding (FISTA) method. This algorithm combines the characteristics of the massive MU-MIMO channel with the second-order Taylor expansion to construct the surrogate function in the MM method, in which minimizing this surrogate function is the worst-case of the system. Specifically, we expand the suggested CE precoding algorithm to involve the discrete constant envelope (DCE) precoding case. In addition, we thoroughly examine the exact property, convergence, and computational complexity of the proposed algorithm. Simulation results demonstrate that the proposed CE precoding algorithm can achievean uncoded biterror rate (BER) performance gain of roughly 1dB compared to the existing CE precoding algorithm and has an acceptable computational complexity. This performance advantage also exists when it comes to DCE precoding.

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FANG, Shu, Li-hua LI, and Ping ZHANG. "Grassmannian precoding MU-MIMO scheme." Journal of China Universities of Posts and Telecommunications 15, no. 3 (September 2008): 105–17. http://dx.doi.org/10.1016/s1005-8885(08)60116-8.

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Lukic, Djordje B., Goran B. Markovic, and Dejan D. Drajic. "Two-Stage Precoding Based on Overlapping User Grouping Approach in IoT-Oriented 5G MU-MIMO Systems." Wireless Communications and Mobile Computing 2021 (January 7, 2021): 1–13. http://dx.doi.org/10.1155/2021/8887445.

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Downlink transmission techniques for multiuser (MU) multiple-input multiple-output (MIMO) systems have been comprehensively studied during the last two decades. The well-known low complexity linear precoding schemes are currently deployed in long-term evolution (LTE) networks. However, these schemes exhibit serious shortcomings in scenarios when users’ channels are strongly correlated. The nonlinear precoding schemes show better performance, but their complexity is prohibitively high for a real-time implementation. Two-stage precoding schemes, proposed in the standardization process for 5G new radio (5G NR), combine these two approaches and present a reasonable trade-off between computational complexity and performance degradation. Before applying the precoding procedure, users should be properly allocated into beamforming subgroups. Yet, the optimal solution for user selection problem requires an exhaustive search which is infeasible in practical scenarios. Suboptimal user grouping approaches have been mostly focused on capacity maximization through greedy user selection. Recently, overlapping user grouping concept was introduced. It ensures that each user is scheduled in at least one beamforming subgroup. To the best of our knowledge, the existing two-stage precoding schemes proposed in literature have not considered overlapping user grouping strategy that solves user selection, ordering, and coverage problem simultaneously. In this paper, we present a two-stage precoding technique for MU-MIMO based on the overlapping user grouping approach and assess its computational complexity and performance in IoT-oriented 5G environment. The proposed solution deploys two-stage precoding in which linear zero forcing (ZF) precoding suppresses interference between the beamforming subgroups and nonlinear Tomlinson-Harashima precoding (THP) mitigates interuser interference within subgroups. The overlapping user grouping approach enables additional capacity improvement, while ZF-THP precoding attains balance between the capacity gains and suffered computational complexity. The proposed algorithm achieves up to 45% higher MU-MIMO system capacity with lower complexity order in comparison with two-stage precoding schemes based on legacy user grouping strategies.

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Lukic, Djordje B., Goran B. Markovic, and Dejan D. Drajic. "Two-Stage Precoding Based on Overlapping User Grouping Approach in IoT-Oriented 5G MU-MIMO Systems." Wireless Communications and Mobile Computing 2021 (January 7, 2021): 1–13. http://dx.doi.org/10.1155/2021/8887445.

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Downlink transmission techniques for multiuser (MU) multiple-input multiple-output (MIMO) systems have been comprehensively studied during the last two decades. The well-known low complexity linear precoding schemes are currently deployed in long-term evolution (LTE) networks. However, these schemes exhibit serious shortcomings in scenarios when users’ channels are strongly correlated. The nonlinear precoding schemes show better performance, but their complexity is prohibitively high for a real-time implementation. Two-stage precoding schemes, proposed in the standardization process for 5G new radio (5G NR), combine these two approaches and present a reasonable trade-off between computational complexity and performance degradation. Before applying the precoding procedure, users should be properly allocated into beamforming subgroups. Yet, the optimal solution for user selection problem requires an exhaustive search which is infeasible in practical scenarios. Suboptimal user grouping approaches have been mostly focused on capacity maximization through greedy user selection. Recently, overlapping user grouping concept was introduced. It ensures that each user is scheduled in at least one beamforming subgroup. To the best of our knowledge, the existing two-stage precoding schemes proposed in literature have not considered overlapping user grouping strategy that solves user selection, ordering, and coverage problem simultaneously. In this paper, we present a two-stage precoding technique for MU-MIMO based on the overlapping user grouping approach and assess its computational complexity and performance in IoT-oriented 5G environment. The proposed solution deploys two-stage precoding in which linear zero forcing (ZF) precoding suppresses interference between the beamforming subgroups and nonlinear Tomlinson-Harashima precoding (THP) mitigates interuser interference within subgroups. The overlapping user grouping approach enables additional capacity improvement, while ZF-THP precoding attains balance between the capacity gains and suffered computational complexity. The proposed algorithm achieves up to 45% higher MU-MIMO system capacity with lower complexity order in comparison with two-stage precoding schemes based on legacy user grouping strategies.

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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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Son, Vu Van, Nguyen Le Cuong, Nguyen Thu Phuong, Tran Manh Hoang, and Pham Thanh Hiep. "Approximation of Capacity for Downlink Multi-User System with Combination of Precoding and NOMA Methods." Applied Sciences 11, no. 22 (November 10, 2021): 10578. http://dx.doi.org/10.3390/app112210578.

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Enhancing performance of downlink MU systems is an attractive and important research for future wireless systems. The non-orthogonal multiple access (NOMA) method was proposed to improve the performance of MU systems. In order to further improve the outage probability (OP) and ergodic capacity (EC) of downlink NOMA MU systems, we propose the combination of precoding and NOMA methods, and then the OP and EC of MU systems with our novel method are derived in scenarios of perfect and imperfect successive interference cancellation (SIC) scheme. Moreover, the closed-form expression of OP and EC for both scenarios is theoretically derived and compared with Monte Carlo simulations. The results show that, the analysis method is accurate, and the proposed combining precoding and NOMA can further enhance the performance of MU systems in comparing with the original orthogonal multiple access method.

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Shaheen, Imad, Abdelhalim Zekry, Fatma Newagy, and Reem Ibrahim. "PAPR reduction for FBMC/OQAM using hybrid scheme of different Precoding transform and mu-law companding." International Journal of Engineering & Technology 6, no. 4 (November 14, 2017): 154. http://dx.doi.org/10.14419/ijet.v6i4.8326.

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The filter banks multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) is developing multicarrier modulation technique used in the next wireless communication system (5G). FBMC/OQAM supports high data rate and high band width efficiency. However, one of the major drawbacks of FBMC system is high peak to Average Power Ratio (PAPR) of the transmitted signal, which causes serious degradation in performance of the system. Therefore, it is required to use a proper PAPR scheme at the transmitter to reduce the PAPR. In this paper, a hybrid scheme is investigated with the combination of preceding transform technique and Mu Law Companding technique to reduce PAPR in FBMC systems. Moreover, four preceding techniques are examined to find the best Precoding technique which can be used with Mu law commanding. We assessed the discrete Hartley transform (DHT). The discrete cosine transformed (DCT), the Discrete Sine Transform (DST), and the Walsh Hadamard transforms (WHT) which are applied separately with Mu Companding. The numerical results verify that the FBMC systems with all Precoding technique combined with Mu law commanding can improve PAPR performance of the signals greatly with the best results achieved when the combination scheme consists of the DST Precoding and Mu law commanding for both PAPR and BER performance.

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De Luna Ducoing, J. C., Yiping Qin, Yun Xue, and Konstantinos Nikitopoulos. "Gyre Precoding for MU-MIMO Systems." IEEE Communications Letters 25, no. 8 (August 2021): 2723–27. http://dx.doi.org/10.1109/lcomm.2021.3082808.

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Jacobsson, Sven, Giuseppe Durisi, Mikael Coldrey, Tom Goldstein, and Christoph Studer. "Quantized Precoding for Massive MU-MIMO." IEEE Transactions on Communications 65, no. 11 (November 2017): 4670–84. http://dx.doi.org/10.1109/tcomm.2017.2723000.

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Urquiza Villalonga, David Alejandro, Hatem OdetAlla, M. Julia Fernández-Getino García, and Adam Flizikowski. "Spectral Efficiency of Precoded 5G-NR in Single and Multi-User Scenarios under Imperfect Channel Knowledge: A Comprehensive Guide for Implementation." Electronics 11, no. 24 (December 19, 2022): 4237. http://dx.doi.org/10.3390/electronics11244237.

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Digital precoding techniques have been widely applied in multiple-input multiple-output (MIMO) systems to enhance spectral efficiency (SE) which is crucial in 5G New Radio (NR). Therefore, the 3rd Generation Partnership Project (3GPP) has developed codebook-based MIMO precoding strategies to achieve a good trade-off between performance, complexity, and signal overhead. This paper aims to evaluate the performance bounds in SE achieved by the 5G-NR precoding matrices in single-user (SU) and multi-user (MU) MIMO systems, namely Type I and Type II, respectively. The implementation of these codebooks is covered providing a comprehensive guide with a detailed analysis. The performance of the 5G-NR precoder is compared with theoretical precoding techniques such as singular value decomposition (SVD) and block-diagonalization to quantify the margin of improvement of the standardized methods. Several configurations of antenna arrays, number of antenna ports, and parallel data streams are considered for simulations. Moreover, the effect of channel estimation errors on the system performance is analyzed in both SU and MU-MIMO cases. For a realistic framework, the SE values are obtained for a practical deployment based on a clustered delay line (CDL) channel model. These results provide valuable insights for system designers about the implementation and performance of the 5G-NR precoding matrices.

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Castillo-Soria, Francisco R., J. Alberto Del Puerto-Flores, Cesar A. Azurdia-Meza, Vinoth Babu Kumaravelu, Jorge Simón, and Carlos A. Gutierrez. "Precoding for RIS-Assisted Multi-User MIMO-DQSM Transmission Systems." Future Internet 15, no. 9 (September 2, 2023): 299. http://dx.doi.org/10.3390/fi15090299.

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This paper presents two precoding techniques for a reconfigurable intelligent surface (RIS)-assisted multi-user (MU) multiple-input multiple-output (MIMO) double quadrature spatial modulation (DQSM) downlink transmission system. Instead of being applied at the remote RIS, the phase shift vector is applied at the base station (BS) by using a double precoding stage. Results show that the proposed RIS-MU-MIMO-DQSM system has gains of up to 17 dB in terms of bit error rate (BER) and a reduction in detection complexity of 51% when compared with the conventional MU-MIMO system based on quadrature amplitude modulation (QAM). Compared with a similar system based on amplify and forward (AF) relay-assisted technique, the proposed system has a gain of up to 18 dB in terms of BER under the same conditions and parameters.

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Kalachikov, A. A. "Numerical Evaluation of the MU-MIMO Beamforming Performance with Channel Estimation." Herald of the Siberian State University of Telecommunications and Information Science 18, no. 1 (December 17, 2023): 109–20. http://dx.doi.org/10.55648/1998-6920-2024-18-1-109-120.

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This paper presents the numerical evaluation of the ZF beamforming algorithm and DFT precoding using the LS channel estimation in the multiuser multiantenna (MU-MIMO) downlink system. The sum rate performance depending on a number of users are presented. The arising inter user correlation degrades the sum rate (spectral efficiency) performance of multiuser MIMO system especially in scenarios where the number of users is larger than the number of antennas at the BS. For MIMO channel simulation the QuaDRiGa channel model reflecting the real propagation conditions is used. The obtained performance of MU-MIMO ZF precoding in spatially correlated channel are compared with DFT precoding based on the empirical cumulative density function of the sum rate of multiple users. Numerical results show that the ZF precoder outperforms the DFT precoder in channel with less spatial correlation. The DFT precoder in spatially more correlated channel has advantage over ZF precoder.

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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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Taneja, Ashu, and Nitin Saluja. "A practical approach to improve product of energy efficiency and capacity rate in MU-MIMO systems." International Journal of Pervasive Computing and Communications 16, no. 2 (May 21, 2020): 183–202. http://dx.doi.org/10.1108/ijpcc-03-2019-0032.

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Purpose The major challenges in the modern-day wireless communication systems are increased co-channel interference owing to large number of users and the increased energy consumption owing to high circuit and/or hardware power consumption. Hence, the purpose of this paper is to present a practical approach involving linear precoding, channel estimation, user selection (US) and transmit antenna selection (AS) for enhanced reliability in multiuser multiple-input multiple output (MU-MIMO) system. Design/methodology/approach The proposed technique considers systematic and optimum deployment of users and transmits antennas for each selected user which enhances the sum rate or the system capacity. The comparison of algorithms, namely, norm-based and capacity-based US is presented with its implementation with precoding techniques, namely, block-diagonalization (BD) and zero-forcing with combining (ZFC) which is used to minimize co-channel interference. In this paper, a power consumption model is proposed for energy efficiency calculation in MU-MIMO system. Also, post analysis, the variant of US and AS algorithms optimizing the performance of BD and ZFC precoding technique is proposed. Findings It is seen that the proposed MU-MIMO system with norm-based US and norm-based AS improves over existing US-based systems by 43% in terms of sum rate and 19% in terms of energy efficiency for 100 users. Originality/value It is seen that the proposed MU-MIMO system with norm-based US and norm-based AS improves over existing US-based systems by 43% in terms of sum rate and 19% in terms of energy efficiency for 100 users.

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Zhang, Hong, Dong Lai Hao, and Xiang Yang Liu. "Pilots Precoding Scheme for Massive MIMO System." Advanced Materials Research 945-949 (June 2014): 2293–96. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.2293.

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There is difficult to acquire channel state information in massive MU-MIMO system. A downlink pilots precoding scheme I s proposed for efficient channel estimation. With the scheme, the BS precodes the pilot sequences and forwards to all users. The channel estimation overhead of this scheme does not depend on the number of BS antennas, and is only proportional to the number of users. We then derive several precoding techniques which enables us to implement the proposed scheme. Finally in simulation the proposed algorithm is compared with conventional algorithms without precoding training in spectral efficiency. The simulation results show that the proposed scheme performs better than the existing schemes.

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Kim, Jinwoo, and Chung G. Kang. "Diversity-Multiplexing-Nulling Trade-Off Analysis of Multiuser MIMO System for Intercell Interference Coordination." Wireless Communications and Mobile Computing 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/5709367.

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A fundamental performance trade-off of multicell multiuser multiple-input multiple-output (MU-MIMO) systems is explored for achieving intercell and intracell interference-free conditions. In particular, we analyze the three-dimensional diversity-multiplexing-nulling trade-off (DMNT) among the diversity order (i.e., the slope of the error performance curve), multiplexing order (i.e., the number of users that are simultaneously served by MU-MIMO), and nulling order (i.e., the number of users with zero interference in a victim cell). This trade-off quantifies the performance of MU-MIMO in terms of its diversity and multiplexing order, while nulling the intercell interference toward the victim cell in the neighbor. First, we design a precoding matrix to mitigate both intercell and intracell interference for a linear precoding-based MU-MIMO system. Then, the trade-off relationship is obtained by analyzing the distribution of the signal-to-noise ratio (SNR) at the user terminals. Furthermore, we demonstrate how DMNT can be applied to estimate the long-term throughput for each mobile station, which allows for determining the optimal number of multiplexing order and throughput loss due to the interference nulling.

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Onukwugha, Chinwe Gilean, Njoku, Donatus Onyedikachi, Jibiri, Janefrances Ebere, Dimoji, and Chigozie. "Bit Error Rate Analysis Of Multiuser Massive MIMO Wireless System Using Linear Precoding." International Journal of Advanced Networking and Applications 14, no. 04 (2023): 5517–22. http://dx.doi.org/10.35444/ijana.2023.14403.

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This paper presents bit error rate (BER) analysis of multiuser (MU) massive multiple input multiple out (MIMO) wireless system using linear precoding techniques. Considering the increasing demand for wireless communication that will provide seamless performance to meet users satisfaction, various precoding schemes have been developed and with massive MIMO projected to be a promising technology for 5G and next generation network. Therefore, this study was basically designed to examine the effect of linear zero forcing (ZF) and minimum mean square error (MMSE) precoders on BER performance of MU massive MIMO system with up to 32 base station antennas (BS) and communicating with up to 5 user mobile terminals (MTs). A model that describes downlink operation of MU massive MIMO wireless communication system with spatial multiplexing employing linear ZF and MMSE precoders such that each user is equipped with single antenna MT resulting in overall access points of 5 antennas was developed in MATLAB. Computer simulations revealed that ZF outperformed MMSE. This observation was validated by similar report on massive MIMO in previous study.

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Liu, Yang, Jun Xuan Wang, Peng Wang, and Ren Kai Yu. "Joint Scheduling and Precoding Based on SLNR Criteria in MU-MIMO System." Applied Mechanics and Materials 668-669 (October 2014): 1273–77. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.1273.

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The user scheduling and precoding schemes in Multi-User Multiple Input Multiple Output (MU-MIMO) system have the problem of high complexity and the performance of traditional criteria is not good. This paper analysis the advantages of Signal to Leakage plus Noise Ratio (SLNR) criteria firstly, then propose a cross-layer design of user scheduling and precoding scheme based on SLNR criteria. The design only uses SLNR criteria and includes an improved SLNR user scheduling scheme which is accomplished by iteration procedure. Numerical results verify the improved user scheduling scheme can improve the performance of sum capacity and average BER and the cross-layer design has lower complexity.

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Khan, Imran, Mohammed H. Alsharif, Mohammad Haseeb Zafar, Madini O. Alassafi, Majid Ashraf, Yongming Huang, Jeong Kim, and Jin Hong Kim. "An Efficient Algorithm for mmWave MIMO Systems." Symmetry 11, no. 6 (June 13, 2019): 786. http://dx.doi.org/10.3390/sym11060786.

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Efficient and Symmetry based precoding plays a key role in wireless communications. In order to improve the transmission performance of multi-user millimeter wave Multiple-Input Multiple-Output (MIMO) (MU-mmWave MIMO) systems, this paper proposes an analog precoding scheme for the receiver of mmWave MIMO with split sub-array hybrid analog and digital architecture. Then, we propose a hybrid analog and digital precoding algorithm based on channel reciprocity (APoCR) to maximize the spectral efficiency by utilizing the triple joint optimization problem, which can be divided into the analog and digital part. The analog combination vectors (ACVs) are obtained by the signal-to-interference-and-noise ratio (SINR) reception maximization of each downlink user and the analog precoding vectors (APVs) are obtained by the SINR reception maximization of each uplink antenna array. The digital precoder of the transmitter is designed after the analog part optimization to alleviate the interference between multiple data streams of the users. The simulation results show that the proposed precoding algorithm has a better sum rate, fast convergence, and improved SINR than the other state-of-the-art algorithms.

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Cao, Bohao, Zheng Xiang, and Peng Ren. "Low complexity transmitter precoding for MU MIMO-OTFS." Digital Signal Processing 115 (August 2021): 103083. http://dx.doi.org/10.1016/j.dsp.2021.103083.

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Castaneda, Oscar, Sven Jacobsson, Giuseppe Durisi, Mikael Coldrey, Tom Goldstein, and Christoph Studer. "1-bit Massive MU-MIMO Precoding in VLSI." IEEE Journal on Emerging and Selected Topics in Circuits and Systems 7, no. 4 (December 2017): 508–22. http://dx.doi.org/10.1109/jetcas.2017.2772191.

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Joham, Michael, Paula M. Castro, Wolfgang Utschick, and Luis Castedo. "Robust Precoding With Limited Feedback Design Based on Precoding MSE for MU-MISO Systems." IEEE Transactions on Signal Processing 60, no. 6 (June 2012): 3101–11. http://dx.doi.org/10.1109/tsp.2012.2186446.

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Humadi, Khaled M., Ahmed Iyanda Sulyman, and Abdulhameed Alsanie. "Spatial Modulation Concept for Massive Multiuser MIMO Systems." International Journal of Antennas and Propagation 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/563273.

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This paper presents the concept of spatial modulation (SM) scheme for massive multiuser MIMO (MU-MIMO) system. We consider a MU-MIMO system whereKusers, each equipped with multiple antennas, are jointly serviced by a multiantenna base station transmitter (BSTx) using appropriate precoding scheme at the BSTx. The main idea introduced here is the utilization of the user’s subchannel index corresponding to the precoding matrix used at the BSTx, to convey extra useful information. This idea has not been explored, and it provides significant throughput enhancements in a multiuser system with large number of users. We examine the performance of the proposed scheme by numerical simulations. The results show that as the number of users and the receiving antennas for each user increase, the overall system throughput gets better, albeit at the cost of some degradation in the BER performance due to interantenna interference (IAI) experienced at the receiver. We then explore zero-padding approach that helps to remove these IAI, in order to alleviate the BER degradations.

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Hwang, Hyun-Sun, Jae-Hyun Ro, Young-Hwan You, Duckdong Hwang, and Hyoung-Kyu Song. "Partial Nulling Regularized Block Diagonalization Using Unfair Channel Selection for Post-Coding with Low-Complexity." Applied Sciences 10, no. 19 (September 28, 2020): 6809. http://dx.doi.org/10.3390/app10196809.

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A number of requirements for 5G mobile communication are satisfied by adopting multi-user multiple input multiple output (MU-MIMO) systems. The inter user interference (IUI) which is an inevitable problem in MU-MIMO systems becomes controllable when the precoding scheme is used. The proposed scheme, which is one of the precoding schemes, is built on regularized block diagonalization (RBD) precoding and utilizes the partial nulling concept, which is to leave part of the IUI at the same time. Diversity gain is obtained by leaving IUI, which is made by choosing the row vectors of the channel matrix that are not nullified. Since the criterion for choosing the row vectors of the channel is the power of the channel, the number of selected row vectors of the channel for each device can be unfair. The proposed scheme achieves performance enhancement by obtaining diversity gain. Therefore, the bit error rate (BER) performance is better and the computational complexity is lower than RBD when the same data rate is achieved. When the number of reduced data streams is not enough for most devices to achieve diversity gain, the proposed scheme has better performance compared to generalized block diagonalization (GBD). The low complexity at the receiver is achieved compared to GBD by using the simple way to remove IUI.

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Lee, Won-Seok, and Hyoung-Kyu Song. "Efficient Channel Feedback Scheme for Multi-User MIMO Hybrid Beamforming Systems." Sensors 21, no. 16 (August 5, 2021): 5298. http://dx.doi.org/10.3390/s21165298.

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This paper proposes an efficient channel information feedback scheme to reduce the feedback overhead of multi-user multiple-input multiple-output (MU-MIMO) hybrid beamforming systems. As massive machine type communication (mMTC) was considered in the deployments of 5G, a transmitter of the hybrid beamforming system should communicate with multiple devices at the same time. To communicate with multiple devices in the same time and frequency slot, high-dimensional channel information should be used to control interferences between the receivers. Therefore, the feedback overhead for the channels of the devices is impractically high. To reduce the overhead, this paper uses common sparsity of channel and nonlinear quantization. To find a common sparse part of a wide frequency band, the proposed system uses minimum mean squared error orthogonal matching pursuit (MMSE-OMP). After the search of the common sparse basis, sparse vectors of subcarriers are searched by using the basis. The sparse vectors are quantized by a nonlinear codebook that is generated by conditional random vector quantization (RVQ). For the conditional RVQ, the Linde–Buzo–Gray (LBG) algorithm is used in conditional vector space. Typically, elements of sparse vectors are sorted according to magnitude by the OMP algorithm. The proposed quantization scheme considers the property for the conditional RVQ. For feedback, indices of the common sparse basis and the quantized sparse vectors are delivered and the channel is recovered at a transmitter for precoding of MU-MIMO. The simulation results show that the proposed scheme achieves lower MMSE for the recovered channel than that of the linear quantization scheme. Furthermore, the transmitter can adopt analog and digital precoding matrix freely by the recovered channel and achieve higher sum rate than that of conventional codebook-based MU-MIMO precoding schemes.

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Liu, Rang, Ming Li, Qian Liu, and A. Lee Swindlehurst. "Secure Symbol-Level Precoding in MU-MISO Wiretap Systems." IEEE Transactions on Information Forensics and Security 15 (2020): 3359–73. http://dx.doi.org/10.1109/tifs.2020.2988127.

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Zhang, Yong Bo, Jian Xin Li, and Wei Min Wen. "Research on Four Water-Filling Power Distribution Schemes in MU-MIMO System." Applied Mechanics and Materials 721 (December 2014): 635–38. http://dx.doi.org/10.4028/www.scientific.net/amm.721.635.

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It is a key issue to distribute the total transmission power among different data streams leading to larger channel capacity or lower bit error rate at the base station in MU-MIMO system. Based on MU-MIMO system model applying block diagonalization precoding (BDP) this paper presented four kinds of water-filling power distribution schemes which had been simulated for random scheduling and multiuser scheduling. The simulation results showed that respective water-filling power distribution owned maximum channel capacity and united water-filling power distribution resulted in the lowest bit error rate (BER).

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Bao, Xiuwen, Ming Jiang, Wenhao Fang, and Chunming Zhao. "PCQNet: A Trainable Feedback Scheme of Precoder for the Uplink Multi-User MIMO Systems." Entropy 24, no. 8 (August 2, 2022): 1066. http://dx.doi.org/10.3390/e24081066.

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Multi-user multiple-input multiple-output (MU-MIMO) technology can significantly improve the spectral and energy efficiencies of wireless networks. In the uplink MU-MIMO systems, the optimal precoder design at the base station utilizes the Lagrange multipliers method and the centralized iterative algorithm to minimize the mean squared error (MSE) of all users under the power constraint. The precoding matrices need to be fed back to the user equipment to explore the potential benefits of the joint transceiver design. We propose a CNN-based compression network named PCQNet to minimize the feedback overhead. We first illustrate the effect of the trainable compression ratios and feedback bits on the MSE between the original precoding matrices and the recovered ones. We then evaluate the block error rates as the performance measure of the centralized implementation with an optimal minimum mean-squared error (MMSE) transceiver. Numerical results show that the proposed PCQNet achieves near-optimal performance compared with other quantized feedback schemes and significantly reduces the feedback overhead with negligible performance degradation.

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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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Wang, Wei, Yan Hui Lu, Duan Yang Li, and Shou Yi Yang. "Joint Linear Precoding and Power Allocation for MU-MIMO CR Systems with Imperfect CSI." Applied Mechanics and Materials 548-549 (April 2014): 1363–67. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.1363.

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This paper proposes a joint linear precoding and power allocation design scheme for multiuser multiple-input multiple-out (MU-MIMO) cognitive radio (CR) systems, where secondary users share the same spectrum with one primary user. The interference power constraint required by the primary user and the multiuser interference generated by secondary users impose negative influence on each secondary user. As a result, it is difficult for secondary users to achieve the ideal information rate. In order to solve the above problem, we respectively adopt Channel Inversion (CI) and Block Diagonalization (BD) for precoding matrices which are set at the transmitter of each secondary user, and then make the system reach a steady state by power allocation. In fact, perfect CSI cannot exist in wireless systems. Therefore, it’s necessary to consider imperfect CSI. Simulation results show BD gains a higher rate for secondary users, but imperfect CSI causes less loss to CI.

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Cui, Gaofeng, Yanjie Dong, Weidong Wang, and Yinghai Zhang. "Coordinated Beamforming with Altruistic Precoding and User Selection for MU-MIMO System." International Journal of Antennas and Propagation 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/628149.

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Other cell interference (OCI) degrades the achievable capacity of downlink multiuser multiple-input multiple-output (MU-MIMO) systems seriously. Among OCI mitigation schemes, methods that sacrificeξdegrees of freedom to nullify the OCI have been proven to be helpful to improve the cell edge throughput. However, since interference nulling schemes can only improve the signal to interference plus noise ratio (SINR) ofξusers, they are not optimal in terms of average cell throughput, especially for low to medium OCI levels. We explore the question whether it is better to improve the SINR of every user in other cells rather than benefitξusers. An altruistic precoding method to minimize the sum of generated interference for all of the other cell users is proposed withξdegrees of freedom being sacrificed. With the altruistic precoding method, we deduce the lower bound on the capacity and solve the multicell user selection problem with a local optimal solution in which only eigenvalues of interfering channels are needed to be shared. Simulation results demonstrate that the proposed method outperforms the existing algorithms at any OCI level. Furthermore, we also analyze the best choice of degrees of freedom used to mitigate OCI through simulation.

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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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Panajotović, Aleksandra, and Daniela Milović. "OPTIMAL PAIR-WISE SUS ALGORITHM AS PROPORTIONAL FAIR ALGORITHM FOR MU-MIMO-OFDM SYSTEMS." Facta Universitatis, Series: Automatic Control and Robotics 19, no. 1 (July 28, 2020): 011. http://dx.doi.org/10.22190/fuacr2001011p.

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In this paper, we research proportional fairness of the optimal pair-wise semi-orthogonal user selection (SUS) algorithm used in the MU-MIMO-OFDM system compliant with IEEE 802.11ac standard. Zero-forcing beamforming (ZFBF) is applied in the system as a precoding technique in order to cancel user interferences. Two different scenarios are considered: homogeneous and heterogeneous. Beside the proportional fairness, a throughput performance of the MU-MIMO-OFDM system is analyzed for both scenarios too. Simulation results show that the optimal pair-wise SUS algorithm is an excellent solution to realize the trade-off between the proportional fairness among users and the achieved system throughput.

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WANG, Weidong, Gaofeng CUI, Sixing LU, and Yinghai ZHANG. "Distributed Precoding with Limited Interference Leakage for MU-MIMO System." IEICE Transactions on Communications E94-B, no. 12 (2011): 3391–94. http://dx.doi.org/10.1587/transcom.e94.b.3391.

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Wang, Wei, Atsushi Harada, and Hidetoshi Kayama. "Enhanced Limited Feedback Schemes for DL MU-MIMO ZF Precoding." IEEE Transactions on Wireless Communications 12, no. 4 (April 2013): 1554–61. http://dx.doi.org/10.1109/twc.2012.030413.120051.

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38

Li, Xiang, Yang Huang, Wei Heng, and Jing Wu. "Machine Learning-Inspired Hybrid Precoding for mmWave MU-MIMO Systems with Domestic Switch Network." Sensors 21, no. 9 (April 25, 2021): 3019. http://dx.doi.org/10.3390/s21093019.

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Hybrid precoding is an attractive technique in MU-MIMO systems with significantly reduced hardware costs. However, it still requires a complex analog network to connect the RF chains and antennas. In this paper, we develop a novel hybrid precoding structure for the downlink transmission with a compact RF structure. Specifically, the proposed structure relies on domestic connections instead of global connections to link RF chains and antennas. Fixed-degree phase shifters provide candidate signals, and simple on-off switches are used to route the signal to antennas, thus RF adders are no longer required. Baseband zero forcing and block diagonalization are used to cancel interference for single-antenna and multiple-antenna users, respectively. We formulate how to design the RF precoder by optimizing the probability distribution through cross-entropy minimization which originated in machine learning. To optimize the energy efficiency, we use the fractional programming technique and exploit the Dinkelbach method-based framework to optimize the number of active antennas. Simulation results show that proposed algorithms can yield significant advantages under different configurations.

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Qi, Fei, Xuetian Zhu, Xinran Zhang, and Songlin Sun. "Hybrid Multicast Transmission for Public Safety Network in 5G." Mobile Information Systems 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/4306356.

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We investigate the application of wireless multicast technology in public safety network (PSN) in future wireless communication system. The hybrid unicast/multicast transmission system is proposed and analyzed in 3D massive multi-input multioutput (MIMO) channel. The mutual coupling channel model is adopted under the different antenna array configuration scenarios. The proposed hybrid system adopts multicast beamforming in the multicast groups as well as multiuser-MIMO (MU-MIMO) linear precoding in the unicast group to increase system throughput. The null space method based interference cancellation is further performed between each group to eliminate signal leakage generated from each group. Comparisons between two types of antenna array configurations, different channel models, linear precoding as well as multicast beamforming, and user grouping strategies for multicast services are presented and analyzed by simulation.

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40

Kalachikov, A. "Numtrical Evaluation of Optimal Precoding Algorithm and Zero Forcing Precoding in MU-MISO Channel with Channel Aging." Proceedings of Telecommunication Universities 10, no. 2 (April 26, 2024): 7–14. http://dx.doi.org/10.31854/1813-324x-2024-10-2-7-14.

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In paper the numerical investigation of the impact of delayed channel state information (CSI) due to user movement and caused channel aging on the performance of multiuser precoder in downlink MISO system. The time variant CSI is obtained by the least squares channel estimation. We consider Zero Forcing algorithm and numerical optimization based solution of calculating precoder vectors maximizimg sum rate of multiuser system. For numerical simulation the QuaDRiGa channel model reflecting the real propagation conditions for moving users is used. The obtained performance of multiuser Zero Forcing and optimization based beamforming in spatially correlated channel are compared based on the empirical cumulative density function of the sum rate of multiple users.

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Niu, Guanchong, Qi Cao, and Manon Pun. "Block Diagonal Hybrid Precoding and Power Allocation for QoS-Aware BDMA Downlink Transmissions." Sensors 20, no. 16 (August 11, 2020): 4497. http://dx.doi.org/10.3390/s20164497.

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Beam Division Multiple Access (BDMA) with hybrid precoding has recently been proposed for multi-user multiple-input multiple-output (MU-MIMO) systems by simultaneously transmitting multiple digitally precoded users’ data-streams via different beams. In contrast to most existing works that assume the number of radio frequency (RF) chains must be greater than or equal to that of data-streams, this work proposes a novel BDMA downlink system by first grouping transmitting data-streams before digitally precoding data group by group. To fully harvest the benefits of this new architecture, a greedy user grouping algorithm is devised to minimize the inter-group interference while two digital precoding approaches are developed to suppress the intra-group interference by maximizing the signal-to-interference-and-noise ratio (SINR) and the signal-to-leakage-and-noise ratio (SLNR), respectively. As a result, the proposed BDMA system requires less RF chains than the total number of transmit data-streams. Furthermore, we optimize the power allocation to satisfy each user’s quality of service (QoS) requirement using the D.C. (difference of convex functions) programming technique. Simulation results confirm the effectiveness of the proposed scheme.

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42

Fu Hongliang, Zhang Beibei, Tao Huawei, and Lu Jing. "Multi-carrier MU-MIMO Limited Feedback Precoding Based on Compressed Sensing." International Journal of Advancements in Computing Technology 5, no. 7 (April 15, 2013): 427–33. http://dx.doi.org/10.4156/ijact.vol5.issue7.52.

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Singh, Jagtar, and Deepak Kedia. "Improved Precoding Algorithm Design for Downlink Large Scale MU-MIMO System." International Journal of Intelligent Engineering and Systems 13, no. 3 (June 30, 2020): 143–53. http://dx.doi.org/10.22266/ijies2020.0630.14.

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Kreyndelin, V. B., and T. B. K. Ben Rejeb. "CLTD-OSIC NONLINEAR PRECODING ALGORITHM FOR MU-MIMO TDD MULTIUSER SYSTEMS." Telecommunications and Radio Engineering 77, no. 7 (2018): 591–602. http://dx.doi.org/10.1615/telecomradeng.v77.i7.30.

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Ahn, Yongjin, Taeyoung Kim, and Chungyong Lee. "A Beam Steering Based Hybrid Precoding for MU-MIMO mmWave Systems." IEEE Communications Letters 21, no. 12 (December 2017): 2726–29. http://dx.doi.org/10.1109/lcomm.2017.2747551.

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Kim, Hak-Jin, Jong-Seob Baek, Ji-Myung Oh, and Jong-Soo Seo. "Improved Leakage-Based Precoding with Vector Perturbation for MU-MIMO Systems." IEEE Communications Letters 16, no. 11 (November 2012): 1868–71. http://dx.doi.org/10.1109/lcomm.2012.092812.121688.

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Wang, Chang-Jen, Chao-Kai Wen, Shi Jin, and Shang-Ho Tsai. "Finite-Alphabet Precoding for Massive MU-MIMO With Low-Resolution DACs." IEEE Transactions on Wireless Communications 17, no. 7 (July 2018): 4706–20. http://dx.doi.org/10.1109/twc.2018.2830343.

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Chen, Chiao-En, and Yuan-Hao Huang. "Lattice-Reduction-Aided One-Bit Precoding for Massive MU-MIMO Systems." IEEE Transactions on Vehicular Technology 68, no. 7 (July 2019): 7184–88. http://dx.doi.org/10.1109/tvt.2019.2915202.

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Fan, YangYu, Qiong Zhao, BoChao Kang, and LiJun Deng. "Equivalent ZF precoding scheme for downlink indoor MU-MIMO VLC systems." Optics Communications 407 (January 2018): 402–9. http://dx.doi.org/10.1016/j.optcom.2017.09.091.

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Berhane, Teklu Merhawit, Wei-Xiao Meng, Lei Chen, Gelmecha Demissie Jobir, and Cheng Li. "SLNR-Based Precoding for Single Cell Full-Duplex MU-MIMO Systems." IEEE Transactions on Vehicular Technology 66, no. 9 (September 2017): 7877–87. http://dx.doi.org/10.1109/tvt.2017.2687472.

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Journal articles on the topic 'MU precoding'

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