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The Journal of China Universities of Posts and Telecommunications 2009年第2期16卷 14-19页

作者： HUANG Jing WANG Ying WU Tong YU Xin-min Wireless Technology Innovation Institute Beijing University of Posts and Telecommunications Beijing 100876 China Key Laboratory of Universal WLreless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

Cooperative relaying techniques can greatly improve the capacity of the multiple input and multiple output （MIMO） wireless system. The transmit power allocation （TPA） strategies for various relaying protocols have become very important for improving the energy efficiency. This article proposes novel TPA schemes in the MIMO cooperative relaying system. Two different scenarios are considered. One is the hybrid decode-and-forward （HDF） protocol in which the zero-forcing （ZF） process is operated on relays, and the other is the decode-and-forward （DF） protocol with relay node and antenna selection strategies. The simulation results indicate that the proposed schemes can bring about significant capacity gain by exploiting the nature of the relay link. Additionally, the proposed TPA scheme in the HDF system can achieve the same capacity as the equal TPA with fewer relay nodes used. Finally, the capacity gain with the proposed schemes increases when the distribution range of relay nodes expands.

关键词： cooperative relaying transmit power allocation hybrid amplify-and-forward zero-forcing

Low complexity resource allocation and scheduling algorithms for downlink SDMA systems

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The Journal of China Universities of Posts and Telecommunications 2009年第5期16卷 33-40页

作者： SUN Kai WANG Ying ZHANG Ping College of Electronic Information Engineering Inner Mongolia University Hohhot 010021 China Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

The downlink zero-forcing beamforming strategy in the case of random packet arrivals is investigated. Under this setting, the relevant fairness criterion is the stabilization of all buffer queues which guarantees a bounded average delay for all users. It has been shown that allocating resources to maximize a queue-length-weighted sum of the rates is a stabilizing policy. However, the high complexity of user selection and the feasible rates determination for optimal scheme may prevent the real-time scheduling operation. Two low complexity algorithms are provided taking the channel state, queue state and orthogonality into account. In particular, the authors pick the first user with the largest product between channel gain and queuing length, and select the remaining users to construct candidate user set based on the greedy user selection method or channel orthogonal user selection method. Then, the power and rate allocation for the selected users are implemented based on the modified water-filling method. The complexity of the proposed algorithms is analyzed. The average delay and average throughput are studied in homogeneous scenarios and heterogeneous scenarios, respectively. Simulation results show that the proposed algorithms can take full advantage of the multi-user diversity gain and provide average delay （or throughput） and fairness improvement compared with channel-aware-only schemes.

关键词： space-division multiple access (SDMA) resource allocation scheduling algorithm zero-forcing

Performance evaluation of channel inversion precoding for downlink multi-user MIMO system

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The Journal of China Universities of Posts and Telecommunications 2009年第5期16卷 20-24页

作者： CHEN Zhi-yong , WANG Wen-bo, PENG Mu-gen, LI Ren Wireless Signal Processing and Network Laboratory, Key Laboratory of Universal Wireless Communication, Ministry of Education, Beijing University of Posts and Telecommunications, Beijing 100876, China Wireless Signal Processing and Network Laboratory Key Laboratory of Universal Wireless Communication Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

In downlink multi-user multi-input multi-output （MU-MIMO） system, not every user （user equipment （UE）） can calculate accurately signal to interference and noise ratio （SINR） without prior knowledge of the other users＇ precoding vector. To solve this problem, this article proposes a channel inversion precoding scheme by using the lower bound of S1NR and zero-forcing （ZF） algorithm. However, the SINR mismatch between lower bound SINR and actual SINR causes the inaccurateness of adaptive modulation and coding （AMC）. As a result, it causes degradation in performance. Simulation results show that channel inversion precoding provides lower throughput than that of single user multi-input multi-output （SU-MIMO） at high signal-to-noise ratio （SNR）（〉14 dB）, due to the SINR mismatch, although the sum-rate of channel inversion precoding is higher than that of SU-MIMO at full SNR regime.

关键词： MU-MIMO channel inversion precoding CQI feedback AMC lower bound S1NR zero-forcing

Energy efficient power allocation strategy for downlink MU-MIMO with massive antennas

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The Journal of China Universities of Posts and Telecommunications 2013年第3期20卷 1-7页

作者： ZHAO Long ZHAO Hui ZHENG Kan Key Laboratory of Universal Wireless Communication Ministry of Education Beijing University of Posts and Telecommunications School of Information and Communication Engineering Beijing University of Posts and Telecommunications

With the increasing energy consumption, energy efficiency （EE） has been considered as an important metric for wireless communication networks as spectrum efficiency （SE）. In this paper, EE optimization problem for downlink multi-user multiple-input multiple-output （MU-MIMO） system with massive antennas is investigated. According to the convex optimization theory, there exists a unique globally optimal power allocation achieving the optimal EE, and the closed-form of the optimal EE only related to channel state information is derived analytically. Then both the approximate and accurate power allocation algorithms with different complexity are proposed to achieve the optimal EE. Simulation results show that the optimal EE obtained by the approximate algorithm coincides to that achieved by the accurate algorithm within the controllable error limitation, and these proposed algorithms perform better than the existing equal power allocation algorithm. The optimal EE and corresponding SE increase with the number of antennas at base station, which is promising for the next generation wireless communication networks.

关键词： green communications SE EE MU-MIMO zero-forcing

A Modified Non-Uniform DMT Transceiver for the Digital Subscriber Line

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China Communications 2007年第4期4卷 40-44页

作者： Sobia Baig M.Junaid Mughal Faculty of Electronic Engineering GIK Institute of Engineering Sciences & TechnologyTopiDistrict Swabi-23460NWFPPakistan

A Non-Uniform Discrete-Multitone(DMT) transceiver can help mitigate the channel-noise enhancement,attributed to zero-forcing equalization (ZFE) technique,by splitting the channel frequency response into octave spaced *** paper presents a novel quantitative analys is of the channel-noise enhancement in different subbands of the Non-Uniform DMT *** order to improve the bit error rate(BER) performance,a modified Non-Uniform DMT transceiver is *** BER performance of the modified Non-Uniform DMT system is compared with that of the Non-Uniform DMT and conventional DMT systems in a Digital Subscriber Line(DSL).

关键词： Non-Uniform DMT wavelet filter banks zero-forcing equalization

An effective approach for low-complexity maximum likelihood based automatic modulation classification of STBC-MIMO systems

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Frontiers of Information Technology & Electronic Engineering 2020年第3期21卷 465-476页

作者： Maqsood H.SHAH Xiao-yu DANG College of Electronic and Information Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China

A low-complexity likelihood methodology is proposed for automatic modulation classification of orthogonal space-time block code(STBC)based multiple-input multiple-output(MIMO)*** exploit the zero-forcing equalization technique to modify the typical average likelihood ratio test(ALRT)*** proposed ALRT function has a low computational complexity compared to existing ALRT functions for MIMO systems *** proposed approach is analyzed for blind channel scenarios when the receiver has imperfect channel state information(CSI).Performance analysis is carried out for scenarios with different numbers of ***-STBC systems with 2×2 and 2×1 and space-time transmit diversity with a 4×4 transmit and receive antenna configuration are considered to verify the proposed *** popular modulation schemes are used as the modulation test ***-Carlo simulations are performed to evaluate the proposed methodology,using the probability of correct classification as the *** results show that the proposed approach has high classification accuracy at low signal-to-noise ratios and exhibits robust behavior against high CSI estimation error variance.

关键词： Multiple-input multiple-output Space-time block code Maximum likelihood Automatic modulation classification zero-forcing

FPGA Implementation of MIMO for Visible Light Communication

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FPGA Implementation of MIMO for Visible Light Communication

作者： Richard Mo 上海交通大学

学位级别：硕士

As the radio frequency（RF） spectrum gets more and more congested with our constant use of Wi-Fi and 3G/4G, newer systems are being designed to alleviate if not replace some older ones. Visible Light Communication（VLC）, a system in which information uses visible light as the media to transmit information has been showing promising results for indoor use. Combined with the technologies that are used in RF, it can provide high performance for relatively low costs. Techniques such as the orthogonal frequency division multiplexing modulation and multiple input multiple output（MIMO） can be adapted to work with visible light, they might not necessarily work without adjustment as the characteristics of RF waves and visible light waves *** part of a project to implement a VLC system on a FPGA hardware platform, the MIMO aspect is studied from a VLC point of view, which differs slightly from its RF counterpart. As the SNR is expected to be sufficiently high, a zero-forcing decoder with ordered successive interference cancellation is implemented. To do so, the pseudoinverse of the channel matrix needs to be computed. This is a complex process and can be done via different methods. We opt for the method using the singular value decomposition of a matrix to determine its pseudoinverse. Since resources available on hardware are more restricted than with software, hardware-efficient algorithms are used to get the most of FPGAs.

关键词： visible light communication multiple input multiple output spatial multiplexing V-BLAST zero-forcing

Enhancing Security in Cognitive Radio Multicast Networks Using Interference Power

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Journal of Computer and Communications 2019年第12期7卷 66-78页

作者： Rezwana Sultana Md. Zahurul Islam Sarkar Md. Selim Hossain Department of Electrical and Electronic Engineering Rajshahi University of Engineering and Technology Rajshahi Bangladesh

In this paper, security issue in multiple input multiple output (MIMO) multicasting system has been analyzed in the presence of a group of eavesdroppers in cognitive radio networks (CRNs). Primary base station (PBS) and secondary base station (SBS) communicate with multiple primary and secondary receivers, respectively via a precoding relay having multiple antennas. At first, considering interference the secrecy multicast capacity at the primary receivers (PRs) and the secondary receivers (SRs) has been calculated and investigated the impact of interferences on it. Then, the zero-forcing (ZF) precoding technique at the relay has been employed which enhances the secrecy multicast capacity at the PRs and SRs by zeroing the impact of interference on each other. Secondly, the existing constructive interference energy of the communication medium employing selective precoding (SP) technique at the relay has been used to improve the secrecy multicast capacity of the PRs and SRs. Finally, phase alignment precoding (PAP) technique at the relay has been introduced which uses the destructive part of interference for further increase in the secrecy multicast capacity at the PRs and SRs. It is observed that among the three precoding techniques, the best performance is achieved by using the PAP at the relay in terms of secrecy multicast capacity and secure outage probability analysis. This is due to the fact that PAP technique at the relay not only uses the constructive interference part but also it rotates the destructive interference part in such a way that the resulting interference is always instantaneously constructive. So using these precoding relays interference power can be used to enhance system performance without increasing base station power.

关键词： Primary Users Secondary Users Cognitive Radio Network Selective Precoding zero-forcing Precoding Phase Alignment Precoding and Multicasting

Vector Precoding for Multiuser MIMO Downlink System under Different Qos Requirements

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网友世界 2012年第6期 23-26页

作者：方赓 Department of Information Technology Nanjing College of Chemical Technology

The conventional zero-forcing vector precoding can provide the same SNR for decentralized receiving *** order to meet different Qos requirement of multimedia applications,we modified the conventional precoding matrix by using a diagonal matrix named relative SNR control matrix so that different SNR can be got for different users＇ ***,with the new precoding matrix used,we analyze the average SNR of all *** find that if a proper perturbation vector is chosen under the power constraint,the average SNR can be ***,we indicate that the choice of perturbation vector is a K-dimensional problem which has low complexity algorithm to *** shows that our scheme is very effective for multimedia applications.

关键词： MIMO Vector Precoding zero-forcing