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On Detection Strategies for linearly Precoded MIMO-OFDM Systems with CSIT

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2013年第12期12卷 5979-5991页

作者： Riera-Palou, Felip Femenias, Guillem Univ Balearic Isl Mobile Commun Grp Mallorca 07122 Illes Balears Spain

This paper explores in detail the application of optimum detection based on maximum likelihood principles in linearly precoded subcarrier cooperative MIMO-OFDM systems. Two different strategies, full spreading and efficient spreading, are presented to disperse the information in the frequency and space domains with the objective of increasing the diversity gain of the system under the assumption of optimum detection at the receiver. The application of efficient spreading at the transmitter allows the implementation of a low-complexity optimal detector that combines linear and non-linear processing. These two techniques, full and efficient spreading, represent different operating points in the performance-complexity plane as shown by the analytical derivation of their diversity order. Remarkably, this analysis serves to reveal and quantify the benefits of subcarrier cooperation with optimum reception. Finally, and in order to highlight the benefits of the proposed approach in practical setups such as those found in contemporary wireless standards, the receiver architectures are extended to operate with soft information, thus allowing the use of iterative soft based receivers. Simulation results demonstrate that efficient spreading in combination with iterative decoding is an attractive combination enabling the implementation of high throughput wireless systems with a large degree of robustness.

关键词： MIMO-OFDM linear precoding maximum likelihood detection (MLD) diversity analysis

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Cyclic Delay Diversity with linear precoding Technique adopted in OFDM Systems

Cyclic Delay Diversity with Linear Precoding Technique adopt...

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11th International Conference on Advanced Communication Technology

作者： Hui, Bing Chang, KyungHi Inha Univ Grad Sch Informat Technol & Telecommun Inchon South Korea

ISBN: (纸本)9788955191387

Cyclic delay diversity (CDD) is considered a simple approach to exploit the frequency diversity, to improve the system performance in orthogonal frequency division multiplexing (OFDM) systems. Also, the linear precoding technique can significantly improve the performance of communication systems by exploiting the channel state information (CSI). In order to achieve enhanced performance, we propose applying linear precoding to the conventional CDD-OFDM transmit diversity schemes over Rayleigh fading channels. The proposed scheme works effectively with the accurate CSI in time-division-duplex (TDD) OFDM systems with CDD, where the reciprocity is assumed instead of channel state feedback. For a bit error rate (BER) of 10(-4) and the mobility of 3 km/h, simulation results show that a gain of 6 dB is achieved by the proposed scheme over both flat fading and Pedestrian A (Ped A) channels, compared to the conventional CDD-OFDM system. On the other hand, for a mobility of 120 km/h, a gain of 2.7 dB and 3.8 dB is achieved in flat fading and Vehicular A (Veh A) channels, respectively.

关键词： Cyclic Delay Diversity linear precoding OFDM Reciprocity Frequency-Division-Duplex (FDD) TDD

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Bidirectional Cellular Relay Network with Distributed Relaying

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2013年第10期31卷 2082-2098页

作者： Wang, Fanggang Yuan, Xiaojun Liew, Soung Chang Li, Yonghui Beijing Jiaotong Univ State Key Lab Rail Traff Control & Safety Sch Elect & Informat Engn Beijing Peoples R China Chinese Univ Hong Kong Inst Network Coding Hong Kong Hong Kong Peoples R China Chinese Univ Hong Kong Dept Informat Engn Hong Kong Hong Kong Peoples R China Univ Sydney Sch Elect & Informat Engn Sydney NSW 2006 Australia

In this paper, we consider a bidirectional cellular relay network with distributed relays where a single base station exchanges information with multiple independent users through multiple single-antenna relays. We design the transceivers at the base station, the relays, and the users. The related optimization problems are generally non-convex and difficult to solve. In this paper, we propose a unified framework to design the transceiver algorithms based on two criteria, i.e. weighted sum MSE minimization and sum rate maximization. Specifically, we show that the sum rate maximization problem can be converted into an iterative weighted sum MSE minimization problem. Low-complexity iterative algorithms are developed for both weighted sum MSE minimization and sum rate maximization optimization problems. However, the convergence points of the proposed iterative algorithms are sensitive to the initial conditions, especially in the high signal-to-noise ratio (SNR) regime. For this reason, we further derive the high-SNR asymptotically optimal solutions and use them as the initials for the proposed iterative algorithms. Simulation results show that the proposed scheme can approximately double the system throughput, compared to the conventional four-stage transmission schemes.

关键词： Distributed relay linear precoding minimum mean square error (MMSE) physical-layer network coding

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Scalable Video Broadcast Over Downlink MIMO-OFDM Systems

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2013年第2期23卷 212-223页

作者： Yang, Zan Wang, Xiaodong Peking Univ State Key Lab Adv Opt Commun Syst & Networks Beijing 100871 Peoples R China Columbia Univ Dept Elect Engn New York NY 10027 USA King Abdulaziz Univ Jeddah 21413 Saudi Arabia

We propose a cross-layer design framework for efficient broadcasting scalable H. 264 videos over the downlink multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing systems. The objective is to maximize the average peak signal-to-noise ratio of the received video streams by jointly optimizing video layer extraction, subcarrier allocation, modulation and coding, and transmit precoding, considering the heterogeneity of video sources and channel conditions. Specifically, to exploit the MIMO channel, we employ a codebook-based linear transmit precoding strategy with limited feedback. Given the fact that different quality layers of the video have different importance, we propose an adaptive modulation and coding scheme, where a fixed coding rate is used for each quality layer and unequal error protection is implemented for different layers. We further propose a subcarrier allocation strategy to assign transmission channels for different layers of different users' videos, to satisfy the decoding dependence constraints among the video layers and to maximize the reconstructed video quality. The proposed scalable video broadcast solution has a low complexity and low signaling overhead, which makes it suitable for practical implementations. We provide experimental results to demonstrate the effectiveness of the proposed solution, using both model-based simulations and an end-to-end software simulation testbed.

关键词： Adaptive modulation and coding auction algorithm downlink broadcast H.264 limited feedback linear precoding MIMO-OFDM scalable video subcarrier allocation

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Blind Frequency Ambiguity Resolution in OFDM Systems Using a linear Precoder

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WIRELESS PERSONAL COMMUNICATIONS 2013年第1期71卷 577-588页

作者： Xu, Weiyang Fu, Xiaolin Chongqing Univ Coll Commun Engn Chongqing 400044 Peoples R China Chongqing Jiaotong Univ Sch Mechatron & Automot Engn Chongqing 400074 Peoples R China

This paper presents a technique of the blind frequency ambiguity resolution for orthogonal frequency division multiplexing systems. The basic idea behind this method is a linear precoding scheme applied to data in predefined subcarriers before the inverse discrete Fourier transform to deploy a correlation structure, thus the integer part of the carrier frequency offset can be estimated after the discrete Fourier transform via cross correlation operations among these subcarriers. Performance analysis is carried out to gain insight into the relationship between the false estimation probability and system parameters. Allocation of these predefined subcarriers is optimized to avoid false estimation. Finally, numerical simulations are conducted to demonstrate the efficiency of the proposed method and the performance comparison with the existing estimators.

关键词： OFDM IFO Blind estimation linear precoding

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Partial Stream Relaying in MIMO Relay Communications

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2013年第1期62卷 205-218页

作者： Ryu, Jong Yeol Choi, Wan Kim, Dong In Korea Adv Inst Sci & Technol Dept Elect Engn Taejon 305701 South Korea Sungkyunkwan Univ Sch Informat & Commun Engn Suwon 440746 South Korea

For a decode-and-forward (DF)-based multiple-input-multiple-output (MIMO) relaying system, we propose a novel partial-information relaying scheme that adaptively controls the number of streams to be forwarded to the destination. In the first transmission phase, a source node broadcasts data streams that consist of nonforwarding and forwarding streams. In the second transmission phase, a relay node forwards only forwarding streams to the destination, and a destination node decodes both nonforwarding and forwarding streams by successive interference cancellation. We consider two possible scenarios according to the availability of the channel-state information (CSI) at the source. The first scenario is that no CSI is available at the source, and therefore, a source node broadcasts data streams with equal power allocation. In this scenario, the number of data streams to be forwarded by the relay is determined according to the available CSI at the relay. For the second scenario, where the perfect CSI is available at the source, we propose a linearly combined precoding matrix for rate maximization. We also propose suboptimal schemes to reduce the complexity of the precoding design. Our analytical and numerical results show that the proposed scheme achieves a substantially higher rate than both the conventional relaying scheme, which forwards all the received streams, and the direct transmission scheme without relaying, regardless of CSI availability at the source.

关键词： Decode-and-forward (DF)-based relaying linear precoding multiple-input-multiple-output (MIMO)

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Weighted Sum Capacity Maximization Using a Modified Leakage-Based Transmit Filter Design

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2013年第3期62卷 1177-1188页

作者： Patcharamaneepakorn, Piya Doufexi, Angela Armour, Simon M. D. Univ Bristol Ctr Commun Res Bristol BS8 1UB Avon England

This paper proposes a linear transmit filter design to maximize weighted sum capacity (WSC) in multiuser multiple-input-multiple-output (MU-MIMO) systems. The proposed scheme is based on a modified signal-to-leakage-plus-noise ratio (SLNR) criterion, which integrates receiver structures and power allocations into the precoder design and can efficiently exploit unused receiver subspaces. Based on the proposed transmitter (TX) design with receive matched filters (MFs), the WSC maximization problem can be simplified to power-allocation and data-stream selection problems. A power-allocation algorithm for finding a local optimal solution is also proposed and is shown to be obtained by the iteration of closed-form water-filling (WF) solutions. Furthermore, a low-complexity user and substream selection is proposed as an alternative solution to maximize WSC. Simulation results show that the proposed algorithms outperform the conventional scheme and achieve comparable performance to a joint transceiver design, despite requiring simpler receiver structures.

关键词： Iterative water filling (WF) linear precoding multiuser multiple-input multiple-output (MIMO) signal-to-leakage-plus-noise ratio (SLNR) user selection

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Min-Max Power Allocation in Cellular Networks With Coordinated Beamforming

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2013年第2期31卷 287-302页

作者： Zakhour, Randa Hanly, Stephen V. Amer Univ Sci & Technol Sch Engn Lebanon NH USA Lebanese Int Univ Lebanon NH USA Macquarie Univ Dept Elect Engn N Ryde NSW 2109 Australia

This paper considers base station (BS) cooperation in the form of coordinated beamforming, focusing on min-max fairness in the power usage subject to target SINR constraints at each single-antenna user. We show that the optimal beamforming strategies have an interesting nested zero-forcing structure. In the asymptotic regime where the number of antennas at each BS and that of users in each cell both grow large with their ratio tending to a finite constant, the dimensionality of the optimization problem that needs to be solved is greatly reduced, and only knowledge of statistics is required to solve it. The optimal solution is characterized in general, and an algorithm is proposed that converges to the optimal transmit parameters, for feasible SINR targets. For the two cell case, a simple single parameter characterization is obtained. These asymptotic results provide insights into the average performance, as well as simple but efficient beamforming strategies for the finite system case. In particular, the asymptotically optimal beamformers only require the BSs to have local instantaneous channel state information;the remaining parameters of the beamformers can be calculated using channel statistics, thereby reducing the channel state information estimation and signaling overhead.

关键词： linear precoding power control base station cooperation coordinated beamforming intercell interference large systems analysis random matrices

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linear Precoder Design for MIMO Interference Channels with Finite-Alphabet Signaling

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IEEE TRANSACTIONS ON COMMUNICATIONS 2013年第9期61卷 3766-3780页

作者： Wu, Yongpeng Xiao, Chengshan Gao, Xiqi Matyjas, John D. Ding, Zhi Southeast Univ Natl Mobile Commun Res Lab Nanjing 210096 Jiangsu Peoples R China Missouri Univ Sci & Technol Dept Elect & Comp Engn Rolla MO 65409 USA Air Force Res Lab RIT Rome NY 13441 USA Univ Calif Davis Dept Elect & Comp Engn Davis CA 95616 USA

This paper investigates the linear precoder design for K-user interference channels of multiple-input multiple-output (MIMO) transceivers under finite alphabet inputs. We first obtain general explicit expressions of the achievable rate for users in the MIMO interference channel systems. We study optimal transmission strategies in both low and high signal-to-noise ratio (SNR) regions. Given finite alphabet inputs, we show that a simple power allocation design achieves optimal performance at high SNR whereas the well-known interference alignment technique for Gaussian inputs only utilizes a partial interference-free signal space for transmission and leads to a constant rate loss when applied naively to finite-alphabet inputs. Moreover, we establish necessary conditions for the linear precoder design to achieve weighted sum-rate maximization. We also present an efficient iterative algorithm for determining precoding matrices of all the users. Our numerical results demonstrate that the proposed iterative algorithm achieves considerably higher sum-rate under practical QAM inputs than other known methods.

关键词： Finite alphabet interference channel linear precoding MIMO

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Power Allocation for linearly Precoded OFDM Systems with Imperfect CSIT

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IEEE WIRELESS COMMUNICATIONS LETTERS 2013年第3期2卷 315-318页

作者： Xu, Chongbin Yuan, Xiaojun Ping, Li Lin, Xiaokang City Univ Hong Kong Dept Elect Engn Hong Kong Hong Kong Peoples R China Chinese Univ Hong Kong Dept Informat Engn Inst Network Coding Hong Kong Hong Kong Peoples R China Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China

This paper is concerned with the energy-efficient transmission in linearly precoded orthogonal frequency division multiplexing (OFDM) systems with imperfect channel state information at the transmitter (CSIT). Convolutionally channel coding and iterative linear minimum mean square error (LMMSE) detection are employed. We focus on the design of power allocation strategies for this system to exploit the potential benefit of available CSIT. Numerical results demonstrate that the proposed designs can achieve the advantage provided by the available CSIT efficiently, and meanwhile are robust to the CSIT uncertainty.

关键词： OFDM imperfect CSIT linear precoding iterative LMMSE detection

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