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Low Complexity Discrete Hartley Transform Precoded OFDM System over Frequency-Selective Fading Channel

ETRI JOURNAL 2015年第1期37卷 32-42页

作者： Ouyang, Xing Jin, Jiyu Jin, Guiyue Li, Peng Dalian Polytech Univ Sch Informat Sci & Engn Dalian Liaoning Peoples R China

Orthogonal frequency-division multiplexing (OFDM) suffers from spectral nulls of frequency-selective fading channels. linear precoded (LP-) OFDM is an effective method that guarantees symbol detectability by spreading the frequency-domain symbols over the whole spectrum. This paper proposes a computationally efficient and low-cost implementation for discrete Hartley transform (DHT) precoded OFDM systems. Compared to conventional DHT-OFDM systems, at the transmitter, both the DHT and the inverse discrete Fourier transform are replaced by a one-level butterfly structure that involves only one addition per symbol to generate the time-domain DHT-OFDM signal. At the receiver, only the DHT is required to recover the distorted signal with a single-tap equalizer in contrast to both the DHT and the DFT in the conventional DHT-OFDM. Theoretical analysis of DHT-OFDM with linear equalizers is presented and confirmed by numerical simulation. It is shown that the proposed DHT-OFDM system achieves similar performance when compared to other LP-OFDMs but exhibits a lower implementation complexity and peak-to-average power ratio.

关键词： OFDM linear precoding multipath diversity discrete Hartley transform DHT peak-to-average power ratio PAPR

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Deterministic Equivalent Performance Analysis of Time-Varying Massive MIMO Systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2015年第10期14卷 5795-5809页

作者： Papazafeiropoulos, Anastasios K. Ratnarajah, Tharmalingam Univ London Imperial Coll Sci Technol & Med Dept Elect & Elect Engn London SW7 2AZ England Univ Edinburgh Inst Digital Commun IDCoM Edinburgh EH9 3JL Midlothian Scotland

Delayed channel state information at the transmitter (CSIT) due to time variation of the channel, coming from the users' relative movement with regard to the BS antennas, is an inevitable degrading performance factor in practical systems. Despite its importance, little attention has been paid to the literature of multi-cellular multiple-input massive multiple-output (MIMO) system by investigating only the maximal ratio combining (MRC) receiver and the maximum ratio transmission (MRT) precoder. Hence, the contribution of this work is designated by the performance analysis/comparison of/with more sophisticated linear techniques, i.e., a minimum-mean-square-error (MMSE) detector for the uplink and a regularized zero-forcing (RZF) precoder for the downlink are assessed. In particular, we derive the deterministic equivalents of the signal-to-interference-plus-noise ratios (SINRs), which capture the effect of delayed CSIT, and make the use of lengthy Monte Carlo simulations unnecessary. Furthermore, prediction of the current CSIT after applying a Wiener filter allows to evaluate the mitigation capabilities of MMSE and RZF. Numerical results depict that the proposed achievable SINRs (MMSE/RZF) are more efficient than simpler solutions (MRC/MRT) in delayed CSIT conditions, and yield a higher prediction at no special computational cost due to their deterministic nature. Nevertheless, it is shown that massive MIMO are preferable even in time-varying channel conditions.

关键词： Massive MIMO delayed CSIT channel estimation channel prediction linear precoding linear detection

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Energy-Aware and Rate-Aware Heuristic Beamforming in Downlink MIMO OFDMA Networks With Base-Station Coordination

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2015年第7期64卷 2897-2910页

作者： Venturino, Luca Buzzi, Stefano Univ Cassino & Southern Lazio Dept Elect & Informat Engn DIEI I-03043 Cassino Italy Natl Interuniv Consortium Telecommun I-03043 Cassino Italy

This paper addresses the problem of coordinated beamforming across a group of base stations (BSs) and frequency slots in the downlink of a multiple-input multiple-output (MIMO) orthogonal frequency-division multiple-access (OFDMA) cellular network. Three figures of merit are considered for system design under a per-BS power constraint: 1) the weighted sum of the rates (WSR) on the frequency slots of the coordinated BSs;2) the global energy efficiency (GEE), defined as the ratio between the network sum rate and the corresponding consumed power;and 3) the weighted sum of the energy efficiencies (WSEE) on the frequency slots of the coordinated BSs. The Karush-Kuhn-Tucker (KKT) conditions of the considered optimization problems are first derived to gain insight into the structure of the optimal beam-formers. Then, we propose a suboptimal design method that can be applied to all considered figures of merit. Numerical results are provided to assess the performance of the proposed beamforming strategies.

关键词： Base-station (BS) coordination beamforming cellular network downlink energy efficiency linear detection linear precoding multiple-input multiple-output (MIMO) orthogonal frequency-division multiple access (OFDMA) spectral efficiency sum-rate

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Asymptotic Rate Analysis of Downlink Multi-User Systems With Co-Located and Distributed Antennas

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2015年第6期14卷 3046-3058页

作者： Wang, Junyuan Dai, Lin City Univ Hong Kong Dept Elect Engn Kowloon Hong Kong Peoples R China

A great deal of efforts have been made on the performance evaluation of distributed antenna systems (DASs). Most of them assume a regular base-station (BS) antenna layout where the number of BS antennas is usually small. With the growing interest in cellular systems with large antenna arrays at BSs, it becomes increasingly important to study how the BS antenna layout affects the rate performance when a vast number of BS antennas are employed. This paper presents a comparative study of the asymptotic rate performance of downlink multi-user systems with multiple BS antennas either co-located or uniformly distributed within a circular cell. Two representative linear precoding schemes, maximum ratio transmission (MRT), and zero-forcing beamforming (ZFBF), are considered, with which the effect of BS antenna layout on the rate performance is characterized. The analysis shows that as the number of BS antennas L and the number of users K grow infinitely while L/K -> upsilon, the asymptotic average user rates with the co-located antenna (CA) layout for both MRT and ZFBF are logarithmic functions of the ratio.. With the distributed antenna (DA) layout, in contrast, the scaling behavior of the average user rate closely depends on the precoding schemes. With ZFBF, for instance, the average user rate grows unboundedly as L, K -> infinity and L/ K -> upsilon > 1, which indicates that substantial rate gains over the CA layout can be achieved when the number of BS antennas L is large. The gain, nevertheless, becomes marginal when MRT is adopted.

关键词： Asymptotic rate analysis downlink multi-user system distributed antenna system (DAS) linear precoding maximum ratio transmission (MRT) zero-forcing beamforming (ZFBF)

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An Efficiency Maximization Design for SWIPT

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IEEE SIGNAL PROCESSING LETTERS 2015年第12期22卷 2189-2193页

作者： Quang-Doanh Vu Le-Nam Tran Farrell, Ronan Hong, Een-Kee Kyung Hee Univ Sch Elect & Informat Yongin 449701 South Korea Maynooth Univ Dept Elect Engn Maynooth Kildare Ireland

A joint power splitting and beamforming design for multiuser multiple-input single-output (MISO) systems where receivers have capability of decoding information and harvesting energy simultaneously from received signals is considered. The objective is to maximize the ratio of the achieved utility to the total power consumption subject to harvested power requirements and power budget at a base station (BS). The utility function of interest combines the sum rate and the total harvested power. The design problem is nonconvex, and thus, global optimality is difficult to achieve. To solve this problem locally we first convert the problem into a more tractable form, and then propose an iterative algorithm which is guaranteed to achieve a Karush-Kuhn-Tucker solution. Numerical results are provided to demonstrate the superior performance of the proposed method.

关键词： Energy harvesting fractional problem iterative algorithm linear precoding power splitting

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On the Asymptotic Sum Rate of Downlink Cellular Systems With Random User Locations

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IEEE WIRELESS COMMUNICATIONS LETTERS 2015年第3期4卷 333-336页

作者： Girnyk, Maksym A. Mueller, Axel Vehkapera, Mikko Rasmussen, Lars K. Debbah, Merouane KTH Royal Inst Technol SE-10044 Stockholm Sweden Huawei Technol Co Ltd France Res Ctr Math & Algorithm Sci Lab F-92100 Paris France Supelec F-91190 Gif Sur Yvette France Aalto Univ Espoo 02150 Finland

We consider a downlink cellular communication system with a multi-antenna base station (BS). A regularized zero forcing precoder is employed at the BS to manage the inter-user interference within the cell. Using methods from random matrix theory, we derive a deterministic approximation for the achievable ergodic sum rate, taking into account the randomness from both fading and random user locations. The obtained approximation describes well the behavior of finite-sized systems and enables efficient optimization of the precoder matrix.

关键词： Cellular networks downlink broadcast channel linear precoding random matrix theory

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linear precoding of OFDMA Signals to Minimize their Instantaneous Power Variance

Linear Precoding of OFDMA Signals to Minimize their Instanta...

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IEEE Wireless Communications and Networking Conference (WCNC)

作者： Falconer, David Carleton Univ Dept Syst & Comp Engn Ottawa ON K1S 5B6 Canada

ISBN: (纸本)9781424463985

Is there an optimum linear block precoding for orthogonal frequency division multiple access (OFDMA) signals that significantly reduces their instantaneous power variance? We explore this question for linear block-precoded OFDMA signals with contiguous frequency mapping. We find that there is an optimum linear block precoding, but its advantage over DFT precoding (such as that used for the uplink signaling in the 3GPP-LTE standard) is rather small.

关键词： OFDM multicarrier single carrier linear precoding peak to average power ratio nonlinear amplification instantaneous power

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Efficient Weighted Sum Rate Maximization With linear precoding

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2010年第4期58卷 2284-2297页

作者： Guthy, Christian Utschick, Wolfgang Hunger, Raphael Joham, Michael Tech Univ Munich Associate Inst Signal Proc D-80290 Munich Germany

Achieving the boundary of the capacity region in the multiple-input multiple-output (MIMO) broadcast channel requires the use of dirty paper coding (DPC). As practical nearly optimum implementations of DPC are computationally complex, purely linear approaches are often used instead. However, in this case, the problem of maximizing a weighted sum rate constitutes a nonconvex and, in most cases, also a combinatorial optimization problem. In this paper, we present two heuristic nearly optimum algorithms with reduced computational complexity. For this purpose, a lower bound for the weighted sum rate under linear zero-forcing constraints is used. Based on this bound, both greedy algorithms successively allocate data streams to users. In each step, the user is determined that is given an additional data stream such that the increase in weighted sum rate becomes maximum. Thereby, the data stream allocations and filters obtained in the previous steps are kept fixed and only the filter corresponding to the additional data stream is optimized. The first algorithm determines the receive and transmit filters directly in the downlink. The other algorithm operates in the dual uplink, from which the downlink transmit and receive filters can be obtained via the general rate duality leading to nonzero-forcing in the downlink. Simulation results reveal marginal performance losses compared to more complex algorithms.

关键词： Broadcast channel linear precoding multiple-input multiple-output (MIMO) systems

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MIMO Relaying Broadcast Channels With linear precoding and Quantized Channel State Information Feedback

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2010年第10期58卷 5233-5245页

作者： Xu, Wei Dong, Xiaodai Lu, Wu-Sheng Univ Victoria Dept Elect & Comp Engn Victoria BC V8W 3P6 Canada

Multi-antenna relaying has emerged as a promising technology to enhance the system performance in cellular networks. However, when precoding techniques are utilized to obtain multi-antenna gains, the system generally requires channel state information (CSI) at the transmitters. We consider a linear precoding scheme in a MIMO relaying broadcast channel with quantized CSI feedback from both two-hop links. With this scheme, each remote user feeds back its quantized CSI to the relay, and the relay sends back the quantized precoding information to the base station (BS). An upper bound on the rate loss due to quantized channel knowledge is first characterized. Then, in order to maintain the rate loss within a predetermined gap for growing SNRs, a strategy of scaling quantization quality of both two-hop links is proposed. It is revealed that the numbers of feedback bits of both links should scale linearly with the transmit power at the relay, while only the bit number of feedback from the relay to the BS needs to grow with the increasing transmit power at the BS. Numerical results are provided to verify the proposed strategy for feedback quality control.

关键词： Amplify-and-forward relay linear precoding multiple-input multiple-output (MIMO) quantized feedback

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Diversity-Multiplexing Tradeoff Analysis for OFDM Systems With Subcarrier Grouping, linear precoding, and linear Detection

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IEEE TRANSACTIONS ON INFORMATION THEORY 2010年第12期56卷 6078-6096页

作者： Prasad, Narayan Venturino, Luca Wang, Xiaodong NEC Labs Amer Princeton NJ 08540 USA Columbia Univ Dept Elect Engn New York NY 10027 USA Univ Cassino DAEIMI I-03043 Cassino FR Italy

We consider the use of linear constellation precoding and linear detection in a multicarrier OFDM system with multiple receive antennas to obtain improved performance over multipath fading channels at a low complexity. We split the full set of subcarriers into smaller groups and spread the data symbols assigned to each group via precoding matrices. We adopt the diversity-multiplexing tradeoff (DMT) framework and derive the DMT-optimal split of the subcarriers (DMT-optimal grouping) and the DMT-optimal number of symbols assigned to each group (DMT-optimal symbol loading). We determine necessary and sufficient precoder design conditions to achieve DMT optimality and give specific constructions of such precoders. Next, we consider a multiuser OFDMA system and derive an algorithm which divides the available subcarriers among the active users in order to maximize the diversity order of the system (or joint) error probability. We also extend our analysis to OFDM systems equipped with multiple transmit antennas. Finally, we obtain important insights on the role of outer codes in an OFDM system employing linear precoding and linear equalization.

关键词： Diversity-multiplexing tradeoff linear detection linear precoding orthogonal frequency-division multiple access (OFDMA) orthogonal frequency-division multiplexing (OFDM) subcarrier grouping

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