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Optical true time delay pool-based beamforming and limited feedback for reconfigurable intelligent surface-empowered cloud radio access networks

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Science China(Information Sciences) 2021年第10期64卷 88-102页

作者： Huan HUANG Xiaowen WANG Chongfu ZHANG Jie PENG Muchuan YANG Songnian FU Deming LIU Kun QIU School of Information and Communication Engineering Zhongshan InstituteUniversity of Electronic Science and Technology of China School of Electronic Information University of Electronic Science and Technology of ChinaZhongshan Institute School of Information Engineering Guangdong University of Technology School of Optical and Electronic Information Huazhong University of Science and Technology

Introducing reconfigurable intelligent surfaces(RISs) greatly improves the wireless propagation environment. limited to feedback overheads and computing power, the low-complexity precoding and the cost-effective beamforming implementation are urgently demanded in RIS-empowered millimeter-wave cloud radio access networks(mmWave C-RANs). Herein, an optical true time delay pool-based hybrid beamforming(OTTDP-based HBF) scheme, enabling centralized analog beamforming control, is proposed for RIS-empowered mmWave C-RANs. By using codebook quantization techniques, we develop a non-iterative limited feedback(NI-LF) precoding algorithm for the RIS-empowered mmWave C-RAN using the proposed OTTDP-based HBF. In the NI-LF precoding algorithm, the complex joint optimization problem of hybrid precoding and phase-shifting of RIS is equivalently formulated as a maximum ratio transmission(MRT)problem and a sparse reconstruction problem. For an active antenna unit(AAU) equipped with eight antennas, a designed example of the proposed OTTDP is presented. Furthermore, for a RIS-empowered mmWave C-RAN at 28 GHz, the received signal-to-noise ratio(SNR) curves obtained via different precoding schemes are compared and discussed. Compared with the precoding without RIS, the proposed NI-LF precoding by using different codebooks to quantize the phase-shifting of the RIS respectively achieves 20.56, 19.55, and18.93 dB performance improvement for the user located near the 49-element RIS. Moreover, performance degradations due to limited feedback are analyzed. The computational complexity and overhead of the proposed NI-LF precoding algorithm are also given and discussed.

关键词： reconfigurable intelligent surface optical true time delay millimeter-wave cloud radio access network limited feedback

Novel limited feedback scheme under the MIMO broadcast system

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The Journal of China Universities of Posts and Telecommunications 2009年第6期16卷 11-16页

作者： CHENG Tie-zheng,YUAN Chao-wei School of Information and Communication Engineering,Beijing University of Posts and Telecommunications,Beijing 100876,China School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

By deducing the distribution of the normalized channel covariance matrix,a novel limited feedback scheme is proposed under multiple users（MU） multiple-input multiple-output（MIMO） broadcast channel（BC） system.The proposed scheme has advantages in three aspects.First,it has no constraints on the number of users or antennas.Second,each user＇s feedback bits are independent of the number of receiving antennas.Third,the proposed scheme avoids the storage of large-size codebook on the transceivers.Simulation results show that the performance of the proposed scheme is close to the perfect channel state information（CSI） case and it just needs a small number of feedback bits.

关键词： MIMO broadcast channel limited feedback normalized channel covariance

Optimal Power Allocation with limited feedback of Channel State Information in Multi-User MIMO Systems

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China Communications 2020年第2期17卷 163-175页

作者： Kusi Ankrah Bonsu Weiwei Zhou Su Pan Yan Yan Key Lab Broadband Wireless Communication and Sensor Network Technology Ministry of EducationNanjing University of Posts and Telecommunications Nanjing 210003China Global Big Data Technologies Centre(GBDTC) University of Technology SydneySydney 2007Australia

In this paper,an expression for the user’s achievable data rate in the multi-user multiple-input multiple-output(MU-MIMO)system with limited feedback(LF)of channel state information(CSI)is derived.The energy efficiency(EE)is optimized through power allocation under quality of service(QoS)constraints.Based on mathematical equivalence and Lagrange multiplier approach,an energy-efficient unequal power allocation(EEUPA)with LF of CSI scheme is proposed.The simulation results show that as the number of transmitting antennas increases,the EE also increases which is promising for the next generation wireless communication networks.Moreover,it can be seen that the QoS requirement has an effect on the EE of the system.Ultimately,the proposed EEUPA with LF of CSI algorithm performs better than the existing energy-efficient equal power allocation(EEEPA)with LF of CSI schemes.

关键词： energy efficiency unequal power allocation limited feedback MU-MIMO QoSguarantee and precoding

On channel quantization for multi-cell cooperative systems with limited feedback

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Science China(Information Sciences) 2013年第2期56卷 74-89页

作者： HOU XueYing YANG ChenYang LAU Buon Kiong School of Electronics and Information Engineering Beihang University Department of Electrical and Information Technology Lund University

Coherent multi-cell cooperative transmission, also referred to as coordinated multi-point transmission (CoMP), is a promising strategy to provide high spectral efficiency for universal frequency reuse cellular systems. To report the required channel information to the transmitter in frequency division duplexing systems, limited feedback techniques are often applied. Considering that the average channel gains from multiple base stations (BSs) to one mobile station are different and the number of cooperative BSs may be dynamic, it is neither flexible nor compatible to employ a large codebook to directly quantize the CoMP channel. In this paper, we employ per-cell codebooks for quantizing local and cross channels. We first propose a codeword selection criterion, aiming at maximizing an estimated data rate for each user. The proposed criterion can be applied for an arbitrary number of receive antennas at each user and also for an arbitrary number of data streams transmitted to each user. Considering that the resulting optimal per-cell codeword selection for CoMP channel is of high complexity, we propose a serial codeword selection method that has low complexity but yields comparable performance to that of the optimal codeword selection. We evaluate the proposed codeword selection criterion and method using measured CoMP channels from an urban environment as well as simulations. The results demonstrate significant performance gain as compared to an existing low-complexity method.

关键词： base station cooperative transmission channel quantization limited feedback codeword selection

SINR-BASED ANTENNA COMBINING FOR MULTIUSER MIMO-OFDM WITH limited feedback

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Journal of Electronics(China) 2011年第3期28卷 328-333页

作者： Lu Min Feng Guangzeng Meng Qingmin College of Telecommunications and Information Engineering Nanjing University of Posts and Telecommunications Nanjing 210003 China

A multiuser Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) broadcast channel is considered where both transmitter and receivers are equipped with multiple antennas. The Channel State Information (CSI) is quantized and provided through limited feedback links. In the first part of this work, the Maximum Expected SINR Combining (MESC) strategy for feedback decrease is investigated. Then a combination of MESC with subcarrier assigning is presented to further reduce the feedback load. The basic idea is the subcarriers are partitioned into resource blocks. For each block, only one quantized channel vector is feedback. The simulation results show MESC can obtain the performance gain over the relevant combiner strategies in MIMO-OFDM system. Moreover the effectiveness on the reduction of feedback overhead by the use of partitioning blocks in the studied system is evaluated.

关键词： Multiuser Multiple Input Multiple Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) limited feedback Quantization

A Joint feedback Bit and Power Allocation Strategy for Multi-cell Systems over Composite Fading Channels

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Chinese Journal of Electronics 2016年第3期25卷 541-550页

作者： MA Yue WANG Xin WANG Haihong GE Songhu WEI Jibo School of Electronic Science and Engineering National University of Defense Technology

This paper addresses the joint feedback bit allocation(FBA) and Power allocation(PA)problem for a limited feedback coordinated multi-cell transmission system over composite fading channels. The Rayleigh/Lognormal fading channel is considered, and the effects of path loss and the macro-level correlation are also taken into account. A modified performance measure, referred to as the virtual sum rate is adopted to facilitate the analysis. The closed forms of the lower bound on virtual sum rate are derived over uncorrelated and correlated shadowed fading channels. Based on the lower bound, we then formulate an optimization problem of maximizing the virtual sum rate under constraints on the total number of feedback bits per MS and the total transmit power per BS. Considering the tight coupling between the FBA and the PA, we solve the optimization problem by solving an alternating sequence of FBA and PA subproblems using a coordinated ascent searching method. Numerical results show that the proposed strategy can converge in a few iterations and generally yield better performance than the conventional FBA schemes under composite fading channels.

关键词： Rayleigh/Lognormal fading feedback bit allocation(FBA) Power allocation(PA) limited feedback Multi-cell

Pre-processing filter design at transmitters for IBI mitigation in an OFDM system

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Journal of Systems Engineering and Electronics 2013年第5期24卷 722-728页

作者： Xia Wang Lei Wang School of Electronics and Information Engineering Xi'an Jiaotong University

In order to meet the demands for high transmission rates and high service quality in broadband wireless communication systems, orthogonal frequency division multiplexing （OFDM） has been adopted in some standards. However, the inter-block interference （IBI） and inter-carrier interference （ICI） in an OFDM system affect the performance. To mitigate IBI and ICI, some pre-processing approaches have been proposed based on full channel state information （CSI）, which improved the system performance. A pre-processing filter based on partial CSI at the transmitter is designed and investigated. The filter coefficient is given by the optimization processing, the symbol error rate （SER） is tested, and the computation complexity of the proposed scheme is analyzed. Computer simulation results show that the proposed pre-processing filter can effectively mitigate IBI and ICI and the performance can be improved. Compared with pre-processing approaches at the transmitter based on full CSI, the proposed scheme has high spectral efficiency, limited CSI feedback and low computation complexity.

关键词： pre-processing filter inter-block interference （IBI） mitigation limited feedback orthogonal frequency division multiplexing （OFDM）.

feedback threshold with guaranteed QoS in multiuser OFDM systems

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The Journal of China Universities of Posts and Telecommunications 2009年第2期16卷 24-28页

作者： YANG Rui-zhe YUAN Chao-wei TENG Ying-lei ZHANG Yan-hua School of Information and Telecommunication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China School of Electronic Information and Control Engineering Beijing University of Technology Beijing 100124 China

A threshold setting scheme is proposed based on the resource management and limited feedback theory in multiuser orthogonal frequency division multiplexing （OFDM） systems. In adaptive resource allocation, the factors denoting the quality of service （QoS） and fairness are both considered as the user weight. From the aspect of feedback outage probability, the proposed algorithm sets the threshold for each user related to its weight, which brings enough feedback to the user with greater weight. Analysis and simulation results show that, compared with the threshold ignoring weights, the proposed scheme has much lower feedback load while with better QoS.

关键词： OFDM multiuser multimedia traffic limited feedback

Transmission scheme and performance analysis for decode-and-forward MIMO two-way relay systems

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Science in China(Series F) 2009年第12期52卷 2308-2316页

作者： ZHAO Rui YANG LuXi ZHU WeiPing School of Information Science and Engineering Southeast University Nanjing 210096 China Department of Electrical and Computer Engineering Concordia University Montreal QC H3G 1M8 Canada

In rd （DF） MIMO two-way relay systems, the transmission schemes are designed and the closed-form expressions for the outage probability and average symbol error rate （ASER） of the twoway relay system are derived based on two different scenarios of channel state information （CSI）. For perfect CSI, the maximum-ratio-transmission and combining （MRT-MRC） technique is applied to design the beamforming and combining vectors. Without perfect CSI, the transmission scheme with limited feedback is designed, and the analytical results are verified through two kinds of codebooks, i.e., random vector quantization and Grassmann. The simulation results show that, the proposed transmission schemes for the two-way relay system can outperform other transmission schemes in the performance of outage probability and ASER, and the accuracy of the derived closed-form expressions is also verified by the numerical simulations.

关键词： decode-and-forward two-way relay outage probability average symbol error rate MRT-MRC limited feedback