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Tone Reservation for SFBC-OFDM with no Spectral Broadening

FREQUENZ 2010年第7-8期64卷 140-143页

作者： Gazda, J. Drotar, P. Deumal, M. Galajda, P. Kocur, D. Tech Univ Kosice Dept Elect & Multimedia Commun Kosice 04120 Slovakia Univ Ramon Llull Res Grp Electromagnetism & Commun LA SALLE Barcelona Spain

A combination of space-frequency-block-codes (SFBC) with orthogonal frequency division multiplexing (OFDM) has became a promising candidate for high performance 4G broadband wireless communications. However, a widely recognized nonlinear distortion due to the nonlinear power amplifiers reduces the efficiency of the SFBC-OFDM transmission and limits the further network deployment. In this paper, we propose the strategy based on using the well-known tone reservation (TR) technique that was initially proposed to be used in conventional single antenna OFDM systems. However, in OFDM systems TR sacrifices a set of subcarrier prior to the transmission in order to reduce the signal envelope fluctuation, thereby reducing the data rate of the transmission. Here, we propose to use the zero tones introduced during procedure of SFBC encoding using selected orthogonal design instead of reserving the set of subcarriers, which allows achieving practically full data rate of the transmission. Numerical results indicate that the proposed method can significantly reduce the out-of-band radiation to the adjacent channels and therefore improving the overall performance of the system.

关键词： Tone reservation space-frequency block coding orthogonal frequency division multiplex nonlinear distortion MIMO-OFDM

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Receiver Technique for Iterative Estimation and Cancellation of Nonlinear Distortion in MIMO SFBC-OFDM Systems

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IEEE TRANSACTIONS ON CONSUMER ELECTRONICS 2010年第2期56卷 471-475页

作者： Drotar, Peter Gazda, Juraj Galajda, Pavol Kocur, Dusan Pavelka, Pavol Tech Univ Kosice Dept Elect & Multimedia Commun Fac Elect Engn & Informat Kosice Slovakia

Multiple-input multiple-output (MIMO) techniques and orthogonal frequency-division multiplexing (OFDM) can be combined to obtain a promising candidate for next generation wireless communications. However, like a single-input single output (SISO) systems one main disadvantage of MIMO-OFDM is high sensitivity to nonlinear distortion that results in significant loss in power efficiency and performance. In order to improve overall system performance this paper introduces a new iterative method for the detection of nonlinearly distorted symbols received by the receiver of the space-frequency block coded (SFBC) MIMO-OFDM transmission system. The proposed approach is based on the Bussgang theorem application and consists in iterative estimation and accurate cancellation of the nonlinear distortion due to the high power amplifier of the transmitter. The numerical performance evaluation shows that the proposed scheme can achieve significant performance improvement compared to conventional receivers(1).

关键词： space-frequency block coding MIMO-OFDM iterative detection nonlinear distortion high power amplifier

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space-frequency block code for single-carrier FDMA

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ELECTRONICS LETTERS 2008年第11期44卷 690-U44页

作者： Ciochina, C. Castelain, D. Mottier, D. Sari, H. Mitsubishi Elect ITE TCL F-35708 Rennes 7 France Supelec Plateau Moulon F-91192 Gif Sur Yvette France

A full-diversity space-frequency block code (SFBC) for single-carrier frequency-division multiple access (SC-FDMA) systems is presented. The code is designed for two transmit antennas and preserves the low envelope fluctuations of SC signals. The good performance of the proposed scheme over multiple-input multiple-output (MIMO) channels, both in static and in high-speed mobility scenarios, is proved.

关键词： frequency division multiaccess space-frequency block coding multiple input multiple output systems Scandium transmitting antennas Codes block codes single carrier modulation

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Unified model for time-domain implementation of space block coded OFDM

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ELECTRONICS LETTERS 2009年第25期45卷 1336-U88页

作者： Ahmed, A. Said, F. Kings Coll London Ctr Telecommun Res Div Engn London WC2R 2LS England

A new scheme for time-domain implementation of space-frequency block coded (SFBC) OFDM is derived. The scheme has a block structure similar to that of time-domain implemented space-time block coded (STBC) OFDM, leading to a unified block structure for time-domain implementation of either STBC- or SFBC-OFDM, or for adaptive switching between the two. The new scheme is also shown to have complexity reduction advantages over existing schemes in the literature.

关键词： space-frequency block coding UNIFIED MODEL Scheme Masonry construction Self tuning Orthogonal frequency division multiplexing space time block coding

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Adaptive modulation for space-frequency block coded OFDM systems

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AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS 2008年第7期62卷 521-533页

作者： Torabi, Mohammad Ecole Polytech Dept Genie Elect Montreal PQ H3T 1J4 Canada

The growing popularity of both multiple-input multiple-output (MIMO) and orthogonal frequency division multiplexing (OFDM) systems has created the need for adaptive modulation to integrate temporal, spatial and spectral components together. In this article, an overview of some adaptive modulation schemes for OFDNI is presented. Then a new scheme consisting of a combination of adaptive modulation, OFDNI, high-order space-frequency block codes (SFBC), and antenna selection is presented. The proposed scheme exploits the benefits of space-frequency block codes, OFDNI, adaptive modulation and antenna selection to provide high-quality transmission for broadband wireless communications. The spectral efficiency advantage of the proposed system is examined. It is shown that antenna selection with adaptive modulation can greatly improve the performance of the conventional SFBC-OFDM systems. (c) 2007 Elsevier GmbH. All rights reserved.

关键词： OFDM adaptive modulation MIMO space-frequency block coding

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Receiver based compensation of nonlinear distortion in MIMO-OFDM

Receiver based compensation of nonlinear distortion in MIMO-...

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IEEE International Microwave Workshop Series on RF Front-ends for Software Defined and Cognitive Radio Solutions

作者： Drotar, P. Gazda, J. Deumal, M. Galajda, P. Kocur, D. Tech Univ Kosice Dept Elect & Multimedia Commun Letna 9 Kosice Slovakia Univ Ramon Llull LA SALLE Res Grp Electromagnetism & Commun Barcelona Spain

ISBN: (纸本)9781424457533

Multiple antenna orthogonal frequency division multiplex (MIMO-OFDM) is transmission technique being employed in the future software defined/cognitive radio solutions. The main disadvantage of using MIMO-OFDM is its high sensitivity to the nonlinear amplification due to the specific characteristic of the high power amplifier (HPA) in the transmitter front-end. This phenomena results in the large overall performance degradation in terms of the bit error rate (BER). In this contribution, we present an iterative receiver scheme to reduce the BER of MIMO-OFDM systems undergoing nonlinear distortion. The technique consist in the iterative estimation and compensation of the nonlinear distortion introduced by transmitters HPA. As it will be shown by means of the numerical performance evaluation, the proposed technique reduces significantly BER of MIMO-OFDM systems.

关键词： iterative detection MIMO-OFDM nonlinear distortion power amplifier space-frequency block coding

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Evaluation of an orthogonal SFBC channel estimation scheme for MIMO OFDM wireless systems

Evaluation of an orthogonal SFBC channel estimation scheme f...

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International Conference on Wireless Information Networks and Systems

作者： Marousis, A. D. Constantinou, P. Natl Tech Univ Athens Sch Elect & Elect Engn Mobile Radio Commun Lab GR-10682 Athens Greece

ISBN: (纸本)9728865651

This paper presents the design and evaluation of a channel estimation scheme that is efficient by means of both the mean square error (MSE) of channel estimation/tracking and its incorporation in a real MIMO system. The evaluation has been performed over the spatial channel model developed for MIMO simulations according to 802.16e case of 3GPP.25.996, taking also into account all IF and RF stages in the communication chain. Orthogonality has been applied in space-frequency dimension for both preamble and pilot symbols, as well as for the data symbols, with the application of Alamouti's scheme. In 4G multicarrier systems that use space-time-frequency coding, orthogonal design turns into a key factor for the performance of the system since the channel has to remain about constant during the transmission of one orthogonal block, something which becomes quite challenging in highly time-variant propagation channels. Furthermore, space-frequency block coding (SFBC) becomes more efficient as the number of subcarriers increases (802.16e, 802.20, etc). The modified channel estimation scheme applied to MIMO transceiver is also efficient in minimization of the processing requirements at the receiver side by estimating only those channel properties that have been changed assuming that the general channel conditions (low/high mobility) are known. The results presented refer to the normalized MSE of the channel estimator and the overall performance evaluation (BER) of the system in various propagations channels, data rates and forward error correction modes.

关键词： MIMO transceivers channel estimation and tracking OFDM space-frequency block coding link level evaluation

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A channel estimation scheme with switched space-time-frequency orthogonal coding for MIMO OFDM systems

A channel estimation scheme with switched space-time-frequen...

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Mobile Computing and Wireless Communications International Conference (MCWC 2006)

作者： Marousis, A. D. Constantinou, P. Natl Tech Univ Athens Sch Elect & Comp Engn Athens Greece

ISBN: (纸本)9789957486006

This paper presents a channel estimation scheme that is designed for MIMO-OFDM systems capable of operating in time varying and frequency selective propagation channels. Orthogonality is applied, either in space-frequency, or in space-time dimensions interchangeably for both the preamble and pilot symbols. The efficiency of the system is based on the accuracy of the channel estimation and tracking process, realizing the orthogonal property by applying block coding in space-frequency domain for the preamble and in space-time one for pilot symbols. Furthermore, minimization of the processing at the receiver has been applied by estimating only the time-varying channel properties. The evaluation has been performed over the spatial channel model developed for MIMO simulations according to 802.16e case of 3GPP.25.996.

关键词： MIMO transceivers channel estimation and tracking space-time space-frequency block coding

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Distributed Antenna Selection for OFDM space-Time block Coded Diversity 84

Distributed Antenna Selection for OFDM Space-Time Block Code...

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84th IEEE Vehicular Technology Conference (VTC-Fall)

作者： Miyazaki, Hiroyuki Adachi, Fumiyuki Tohoku Univ Res Org Elect Commun Aoba Ku 2-1-1 Katahira Sendai Miyagi 9808577 Japan

ISBN: (纸本)9781509017010

Antenna selection is an important issue for a distributed antenna-based small-cell network (DAN). This paper proposes a distributed antenna (DA) selection for DAN downlink using orthogonal frequency division multiplexing (OFDM) and space-time block coded (STBC) diversity. The proposed DA selection is an iterative algorithm which determines DA groups (each group consists of DAs communicating with a different user equipment (UE)) to maximize the downlink sum capacity by taking into account co-channel interference (CCI). In each iteration, one DA is added/removedto/from one of current DA groups if this increases the sum capacity by the largest amount. This is repeated until the sum capacity starts to decrease or by the prescribed number of times. It is shown by computer simulation that the proposed DA selection algorithm increases the 10% outage sum capacity by about 20% compared to the received signal power-based DA selection (no CCI is considered).

关键词： component Distributed antenna-based small-cell network space-frequency block coding antenna selection

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Enhanced Interference Whitening for Co-Channel Interference Suppression

Enhanced Interference Whitening for Co-Channel Interference ...

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IEEE Wireless Communications and Networking Conference (WCNC)

作者： Yu, Yingqun Lee, Jungwon Kang, Inyup Samsung US R&D Ctr Samsung Mobile Solut Lab San Diego CA 92121 USA

ISBN: (纸本)9781467359399;9781467359382

The co-channel interference (CCI) has become a major throughput-limiting factor for cell-edge users in the modern cellular systems such as the Long Term Evolution (LTE) network. Spatial interference whitening (IW) is an effective low-complexity linear method to suppress colored spatial interference in a MIMO setup. However, for CCIs using Alamouti's type of SFBC (space-frequency block coding) transmission, the conventional per-subcarrier IW fails to exploit the SFBC structure and thus is suboptimal. To address that, we propose an optimal method called enhanced interference whitening (eIW). eIW works on a properly combined augmented MIMO model for two subcarriers involved in the same SFBC encoding block and thus can fully exploit the interference structure. Simulations show that if the interfering cell uses SFBC significant performance gains can be achieved by eIW no matter whether or not SFBC is used for the serving cell.

关键词： space-frequency block coding Cochannel interference optimization method interference interference Long Term Evolution

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