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IEEE 78th Vehicular Technology Conference (VTC Fall)

作者： Budhathoki, Krishna Ram Maleki, Mehdi Bahrami, Hamid Reza Univ Akron Dept Elect & Comp Engn Akron OH 44325 USA

ISBN: (纸本)9781467361873

In this paper, we study the problem of relay precoder design in a multi-antenna non-regenerative relay cognitive radio (CR) system assuming underlay spectrum sharing methodology with the primary users (PUs). An expression for the capacity of the secondary system is derived assuming fixed source covariance matrix. We then consider maximizing this capacity expression subject to a power constraint at the relay and an interference power constraint at the PU due to the secondary relay. We then derive the structure of the relay precoding up to a square matrix that should be chosen optimally. A constrained optimization problem is derived to find this square matrix to maximize the capacity equation. The solution to this optimization problem involves an exhaustive search and the complexity increases with the number of relay antennas. We, therefore, propose an alternative sub-optimal approach with significantly lower complexity to derive the structure of the relay precoding matrix. Through simulation, we compare the effectiveness of the optimal and the sub-optimal approaches to improve the achievable throughput of the CR system. It is shown that both approaches provide a significant improvement in the throughput of the system at different power and interference regimes.

关键词： Cognitive radio multi-input multi-output (MIMO) non-regenerative relaying capacity precoder design

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precoder design and Power Allocation for MIMO Cognitive Radio Two-Way Relaying Systems

Precoder Design and Power Allocation for MIMO Cognitive Radi...

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IEEE International Conference on Communications

作者： Sboui, Lokman Ghazzai, Hakim Rezki, Zouheir Alouini, Mohamed-Slim King Abdullah Univ Sci & Technol Comp Elect & Math Sci & Engn Div Thuwal 239556900 Saudi Arabia Qatar Univ Qatar Mobil Innovat Ctr POB 210531 Doha Qatar Univ Idaho Dept Elect & Comp Engn Moscow ID 83844 USA

In this paper, we study a multiple-antenna two-way relaying (TWR) cognitive radio (CR) system. A space alignment (SA) technique is adopted by the secondary users (SUs) to avoid interference with the primary users (PUs). We derive the optimal power allocation that maximizes the TWR achievable SU sum-rate while respecting the total power budget and the relay power constraints. We also analyze the case in which the relay is able to optimize its gain matrix structure to enhance the SU sum-rate. In the numerical results, we quantify the sum-rate gain of using the SA in the TWR CR and we show that the SU sum-rate is very limited when the relay power is low or the PU power and its resulting interference are high. In addition, we optimize the relay gain using an iterative algorithm and compare between different relay matrix structures.

关键词： MIMO space alignment cognitive radio two-way relaying precoder design

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precoder design for Dual-Stream MIMO Multicasting

Precoder Design for Dual-Stream MIMO Multicasting

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International Conference on Wireless Communications and Signal Processing (WCSP)

作者： Du, Baisheng Xu, Xiaodong Zhang, Zilong Dai, Xuchu Univ Sci & Technol China Dept Elect Engn & Informat Sci Hefei 230027 Peoples R China

ISBN: (纸本)9781479903085

In this paper, we investigate the precoder design for MIMO multicasting, where two data streams are sent from the transmitter and the minimum mean-squared-error decision feedback equalizer is performed at all users. To improve the receiving quality of data streams, we focus on maximizing the minimal signal-to-interference-plus-noise ratio (SINR) for all streams via precoding. Considering that the precoder is composed of a transformation matrix and a rotation matrix, we separate the precoder design into two stages. Firstly we calculate the transformation matrix under the criterion of maximizing the throughput of the multicast channel. Then, by deriving the relationship between the rotation matrix and the SINR, we transform the original problem into a real-valued optimization problem, and moreover, a Lozano's algorithm is proposed to compute the rotation matrix. In particular, for the special case of two users, a constructive method can be applied to directly calculate the rotation matrix. The simulation results show that the proposed design outperforms the existing ones in both the achievable rate and symbol error rate.

关键词： Physical layer multicasting precoder design MMSE-DFE Semidefinite relaxation

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Exploiting Channel Angular Domain Information for precoder design in Distributed Antenna Systems

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2010年第11期58卷 5791-5801页

作者： Chen, Xiaoming Zhang, Zhaoyang Zhejiang Univ Inst Informat & Commun Engn Hangzhou 310027 Zhejiang Peoples R China

In this paper, the benefit of linear precoding along with distributed orthogonal space time block codes (OSTBCs) is exploited to improve the performance of distributed antenna system (DAS). In particular, we propose a novel precoder design method based on channel angular domain parameters, i.e., average angle of arrival (AOA), angular spread (AS), normalized antenna spacing (NAS) and Ricean K-factor, instead of the conventional channel correlation matrix which has been widely used to characterize MIMO channel. Built on the distributed characteristics of DAS, a more realistic non-Kronecker channel model is established, and then the optimal precoder is designed as a function of the above angular domain parameters. Asymptotic analysis reveals that, the optimal precoder acts as a combination of channel precoder and power allocator. Furthermore, the impact of the above angular domain parameters on system performance, including diversity order and coding advantage, is investigated in detail. Specifically, we find that better gain can be achieved with larger K-factor. Finally, our theoretical claims are confirmed by the numerical results.

关键词： Angular domain information distributed antenna system distributed space-time codes diversity order non-Kronecker channel model precoder design

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MSE-Based Source and Relay precoder design for Cognitive Multiuser Multi-Way Relay Systems

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2013年第7期61卷 1770-1785页

作者： Mu, Hua Tugnait, Jitendra K. Auburn Univ Dept Elect & Comp Engn Auburn AL 36849 USA

We consider joint design of source and relay precoders in a cognitive multiuser multi-way relay system, which supports simultaneous transmission of multiple secondary users concurrently with primary network with the help of a relay station. The design criterion is minimum mean-square error (MMSE) of all secondary users under a transmit power constraint for each transmitting node and a constraint on the interference to primary network assuming complete knowledge of the channel state information is available. To solve this non-convex optimization problem, an iterative algorithm is proposed to iteratively solve the precoding matrices at secondary source nodes and relay node, and the decoding matrices at secondary nodes, where each subproblem is convex. To reduce the computational complexity, a matrix distance based non-iterative algorithm which can be implemented in a distributed manner is also proposed. Given the fact that perfect channel state information is usually non-realistic, a robust precoder design is also proposed to address this problem. Simulation results show the effectiveness of our proposed algorithms.

关键词： Cognitive radio interference cancellation minimum mean-square error (MMSE) precoder design relay precoding

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Energy-Efficient precoder design for Downlink Multi-User MISO Networks With Finite Blocklength Codes

IEEE TRANSACTIONS ON GREEN COMMUNICATIONS AND NETWORKING

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IEEE TRANSACTIONS ON GREEN COMMUNICATIONS AND NETWORKING 2021年第1期5卷 160-173页

作者： Singh, Keshav Ku, Meng-Lin Flanagan, Mark F. Univ Coll Dublin Sch Elect & Elect Engn Dublin EH8 9YL 4 Ireland Natl Sun Yat Sen Univ Inst Commun Engn Kaohsiung 80424 Taiwan Natl Cent Univ Dept Commun Engn Taoyuan 32001 Taiwan

One of the key applications in the fifth generation (5G) cellular networks is to support ultra-reliable and low-latency communication (URLLC) which requires extremely high reliability (similar to 99.999%) and low latency (< 1 ms). In this article, the energy efficiency (EE) is maximized for downlink multi-user multiple-input single-output (MISO) networks under short packet transmission. We jointly optimize the precoders at the base station (BS) for serving multiple downlink users and the decoding error probability (DEP) with finite blocklength (FBL) codes, subject to the constraints on the BS transmit power and DEP per URLLC user. This non-convex optimization problem is then accurately approximated by applying the Dinkelbach method and approximating the channel dispersion in the high signal-to-interference-plus-noise ratio (SINR) regime and the entire (practical) SINR regime, respectively. The resulting problems are convex in the design variables of the precoders and DEPs when the remaining variables are held fixed, and using this fact we provide iterative algorithms to efficiently find locally optimal solutions. Furthermore, the convergence of the proposed algorithms and the closed-form expressions of the precoders are also derived. Simulation results validate the effectiveness of the proposed algorithms that support energy-efficient URLLC as well as the impact of various network parameters such as the blocklength, number of users, distance between the BS and URLLC users and the threshold of the DEP on the EE and spectral efficiency (SE) performance.

关键词： precoder design finite blocklength (FBL) codes base station multiple-input single-output (MISO) ultra-reliable low-latency communication (URLLC) multi-user energy efficiency optimization

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Linear precoder design for SWIPT-Enabled Relay Networks With Finite-Alphabet Inputs

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IEEE ACCESS 2020年 8卷 82012-82023页

作者： Chen, Baojun Zhu, Xiaodong Tu, Xiaodong Guo, Yunshan Univ Elect Sci & Technol China Sch Informat & Commun Engn Chengdu 610054 Peoples R China

This paper considers the problem of mutual information maximization in a two-hop relay network with simultaneous wireless information and power transfer (SWIPT), where the relay nodes use the power splitting (PS) scheme to harvest the energy for information forwarding. Unlike previous research, this paper focuses on a more practical scenario, where the inputs to the network are assumed to be finite-alphabet signals. Although each node in the network is assumed to have single antenna, we show that the relay network can be regarded as an effective multiple-input multiple-output (MIMO) system. Our goal is to perform the joint optimization on the precoder at source and PS ratio at relays to maximize the mutual information. Although the formulated problem is nondeterministic polynomial-time (NP)-hard, we theoretically analyze the optimal PS ratio;then, by using the structure of optimization problem, a near optimal precoder design based on semidefinite relaxation (SDR) is proposed;further, to reduce the complexity of algorithm, another precoder design based on search technique, which exploiting the structure of precoder, is developed only with a slight performance degradation. Simulation results verify the efficacy of proposed precoder designs.

关键词： Finite-alphabet inputs precoder design SWIPT relay network

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Performance Enhanced Efficient precoder design with Power Allocation for Multiuser MIMO Downlinks

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IEICE TRANSACTIONS ON COMMUNICATIONS 2013年第7期E96B卷 1962-1967页

作者： Cao, Yuan Xu, Wei Nakamura, Hideo Beijing Jiaotong Univ Sch Elect & Informat Engn State Key Lab Rail Traff Control & Safety Beijing 10044 Peoples R China Southeast Univ Natl Mobile Commun Res Lab Nanjing 210096 Jiangsu Peoples R China Nihon Univ Coll Sci & Technol Dept Elect & Comp Sci Funabashi Chiba 2748501 Japan

This paper investigates a preprocessing technique for a multiuser MIMO downlink system. An efficient joint precoder design with adaptive power allocation is proposed by adopting the channel-diagonalization technique and the minimum mean square error (MMSE) criterion. By exploiting an MMSE-based decoder, we propose an iterative algorithm to design the precoder with further derived closed-form solutions for implementing adaptive power allocation. Simulation results verify the effectiveness of our proposed approach. Compared with conventional benchmark schemes, they show that our proposal matches the performance but with reduced computational complexity.

关键词： multiuser MIMO co-channel interference (CCI) precoder design adaptive power allocation

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Capacity Maximized Linear precoder design for Spatial-Multiplexing MIMO VLC Systems

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IEEE ACCESS 2020年 8卷 63901-63909页

作者： Zhai, Yanrong Chi, Hao Tong, Jun Xi, Jiangtao Hangzhou Dianzi Univ Sch Commun Engn Hangzhou 310018 Peoples R China Univ Wollongong Sch Elect Comp & Telecommun Wollongong NSW 2522 Australia

This paper proposes a novel linear precoder design based on the singular value decomposition (SVD) for multi-input multi-output visible light communications (MIMO VLC). We provide an analytical expression on power allocation subject to the function of maximizing the lower bound of capacity according to the optical wireless communication channel model. The expression is rather different from the radio frequency (RF) communications due to the non-negativity of the transmitted signals in VLC. Furthermore, we design an adaptive bit loading scheme for sub-streams with consideration of the tremendous gain difference among subchannels. Performances of the proposed adaptive power and bits allocation strategy are evaluated in two traditional MIMO VLC scenarios, i.e., a practical 2x2 indoor scenario and a classical 4x4 system that is generated according to the MIMO model. In simulations, the techniques of unipolar M-level pulse amplitude modulation (M-PAM) and spatial-multiplexing (SMP) are employed, and the performance comparison with other SVD-based linear precoders is also given. Simulation results show that the proposed approach can effectively improve the spectral efficiency and guarantee the bit error rate (BER) performance under the same constraints of aggregate optical power budget and non-negativity included by the intensity modulation. It indicates that the strategy of uneven bits and power allocation with full consideration of the ill-conditioned characteristics of subchannels performs better than that based on equal bits transmission in VLC systems.

关键词： Visible light communication spatial-multiplexing precoder design channel capacity

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Broad Coverage precoder design for Synchronization in Satellite Massive MIMO Systems

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IEEE TRANSACTIONS ON COMMUNICATIONS 2021年第8期69卷 5531-5545页

作者： Guo, Weiran Lu, An-An Gao, Xiqi Xia, Xiang-Gen Sci & Technol Informat Syst Engn Lab Nanjing 210007 Peoples R China Southeast Univ Natl Mobile Commun Res Lab Nanjing 210096 Peoples R China Purple Mt Labs Nanjing 211111 Peoples R China Univ Delaware Dept Elect & Comp Engn Newark DE 19716 USA

In this paper, we investigate the massive multi-input multi-output (MIMO) transmission for the satellite communication systems equipped with a uniform rectangular array (URA) and aim to design the precoder with broad coverage radiation power pattern to improve the performance of time and frequency synchronizations. The modified Cramer-Rao vector bounds (MCRVB) are chosen as the benchmark of symbol timing offset and frequency offset estimation problem, which can be viewed as the time and frequency synchronization performance metric for the broad coverage precoder design. By considering the minimax MCRVB criterion and the per-antenna equal power constraint, the precoder design approach is formulated as the non-convex constrained minimax problem over the discrete radiation power pattern. This optimization problem is solved by the smoothing techniques combined with the manifold optimization method. To reduce the calculation complexity, the nonmonotone conjugate gradient method is applied. Simulation results show that the average and the minimum received powers in the coverage area of the proposed scheme are higher than those of the scheme based on fairness criterion. Compared with the existing omnidirectional and broad coverage schemes, the proposed scheme has the best synchronization performance among all the contrast solutions.

关键词： Satellites Massive MIMO Synchronization Manifolds Satellite communication Frequency synchronization Smoothing methods Massive MIMO precoder design URA power pattern synchronization manifold optimization

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