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Distributed space-frequency coding over Broadband Relay Channels

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2008年第11期7卷 4748-4759页

作者： Seddik, Karim G. Liu, K. J. Ray Univ Alexandria Dept Elect Engn Alexandria 21544 Egypt Univ Maryland Dept Elect & Comp Engn College Pk MD 20742 USA Univ Maryland Syst Res Inst College Pk MD 20742 USA

Designing diversity achieving schemes over the wireless broadband fading relay channels is crucial to achieve higher diversity gains. These gains are achieved by exploiting the multi-path (frequency) and cooperative diversities to combat the fading nature of wireless channels. The challenge is how to design space-frequency codes, distributed among randomly located nodes that can exploit the frequency diversity of the wireless broadband channels. In this paper, the design of distributed space-frequency codes (DSFCs) for wireless relay networks is considered. The proposed DSFCs are designed to achieve the frequency and cooperative diversities of the wireless relay channels. The use of DSFCs with the decode-and-forward (DAF) and amplify-and-forward (AAF) protocols is considered. The code design criteria to achieve full diversity, based on the pairwise error probability (PEP) analysis, are derived. For DSFC with the DAF protocol, a two-stage coding scheme, with source node coding and relay nodes coding, is proposed. We derive sufficient conditions for the proposed code structures at the source and relay nodes to achieve full diversity of order NL, where N is the number of relay nodes and L is the number of paths per channel. For the case of DSFC with the AAF protocol, a structure for distributed space-frequency coding is proposed.

关键词： Amplify-and-forward broadband channels decode-and-forward relay channels space-frequency coding

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space-frequency Codes Based on the space-Time Codes With Very Low Complexity for the Decoder

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2013年第9期62卷 4678-4684页

作者： Shahabinejad, Mostafa Hosseini, Fatemeh G. Talebi, Siamak Shahid Bahonar Univ Kerman Dept Elect Engn Kerman Iran Sharif Univ Technol Adv Commun Res Inst Tehran Iran

In this paper, we introduce a family of full-diversity space-frequency codes (SFCs) for the multi-input-multi-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems. The most important feature of the proposed SFCs is that they can be swiftly decoded. More precisely, the decoding complexity on the order of O (M) or O(M-2) can be attained for the proposed full-diversity SFCs, where M is the constellation size. Simulation results have also verified that the proposed SFCs display outstanding performance in comparison with the latest SFC model published in the literature.

关键词： Fading channels frequency-selective channels multi-input-multi-output orthogonal frequency-division multiplexing (MIMO-OFDM)systems space-frequency coding wireless communication

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Full-Diversity space-frequency Trellis Codes Designing Method

Full-Diversity Space-Frequency Trellis Codes Designing Metho...

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13th International Symposium on Communications and Information Technologies (ISCIT) - Communication and Information Technology for New Life Style Beyond the Cloud

作者： Woradit, Kampol Srinakharinwirot Univ Dept Elect Engn Fac Engn Nakhonnayok Thailand

ISBN: (纸本)9781467355803;9781467355780

This paper introduces a method to design spacefrequency trellis codes for a system that combines space-time coding with orthogonal frequency division multiplexing (OFDM) to realize broad-band wireless communications. It has been pointed out in the literature that the frequency-selective fading, which usually occurs in such combined system, turns out to produce a beneficial effect on the error rate performance by providing the frequency diversity in addition to the spatial diversity. This enables space-frequency codes to exploit greater diversity than the space-time codes. However, exhaustive search for space-frequency trellis codes is impractical. The only existing heuristic design method has a drawback in the spectral efficiency, and in turn degrades the coding gain (energy efficiency,) which is also the primary purpose of space-frequency coding. We propose a practical method to design the space-frequency codes that exploit full diversity while maximizes the coding gain at a desired spectral efficiency. The simulation results show the superior error rate performance of the codes designed by the proposed method.

关键词： space-time signal processing space-frequency coding coded MIMO-OFDM energy-efficient communications

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Full-Diversity space-frequency Trellis Codes Designing Method

Full-Diversity Space-Frequency Trellis Codes Designing Metho...

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International Symposium on Communications and Information Technologies

作者： Kampol Woradit Department of Electrical Engineering Faculty of Engineering Srinakharinwirot University Nakhonnayok Thailand

ISBN: (纸本)9781467355797

关键词： space-time signal processing space-frequency coding coded MIMO-OFDM energy-efficient communications

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A Rate-1 space-Time Diversity Method for Rotated 4-QAM Constellations

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WIRELESS PERSONAL COMMUNICATIONS 2012年第2期64卷 211-223页

作者： Hacioglu, Gokce Gangal, Ali Karadeniz Tech Univ Dept Elect & Elect Engn Trabzon Turkey

We propose a rate-1 space-time transmit diversity technique. We obtained second-order diversity by transmitting the real and imaginary parts of the symbols from two antennas. With four transmit antennas, we can add Alamouti coding to reach fourth-order transmit diversity. There is no need to detect symbols jointly in either of these applications. It is possible to use both Alamouti coding and Hadamard spreading diversity with the proposed method, thereby obtaining eighth-order (or even higher) transmit diversity. However, joint detection of the symbols is again required at this point. The proposed technique is a suitable space-frequency coding method for OFDM systems. We used computer simulations to compare our technique with the Alamouti coding, quasi-orthogonal space-time block coding (QOSTBC), and orthogonal space-time block coding (OSTBC) methods. We also compared its performance to that of Hadamard spreading diversity. Alamouti coding performs better than the proposed technique at the second order of transmit diversity, but is also limited to that order. The proposed technique performs better than OSTBC at the same order of the transmit diversity. QOSTBC performs slightly better than the proposed technique at the same order of transmit diversity. However, when all methods have the same detection complexity, the proposed technique performs better than both QOSTBC and Hadamard spreading diversity.

关键词： Diversity space-time coding space-frequency coding Carrier spreading OFDM

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New Full-Diversity space-frequency Block Codes Based on the OSTBCs

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IEEE COMMUNICATIONS LETTERS 2012年第10期16卷 1620-1623页

作者： Mohammadian, Zahra Shahabinejad, Mostafa Talebi, Siamak Shahid Bahonar Univ Kerman Dept Elect Engn Kerman Iran Sharif Univ Technol Adv Commun Res Inst Tehran Iran

In this paper, we introduce new full-diversity spacefrequency block codes (SFBCs) based on orthogonal space-time block codes (OSTBCs). We show that the proposed schemes are capable of attaining full-diversity and rate-one characteristics for two transmit antennas, although the proof of full-diversity property is limited to the real constellations. Also for the QPSK constellation, we present evidences through simulations that demonstrate the full-diversity property of the proposed SFBCs. The proposed SFBCs also benefit from the maximum coding advantage when partial channel state information is available at the transmitter. Simulation results confirm the performance superiority of the proposed codes over other recently proposed SFBCs under the same complexity at the receiver side.

关键词： Wireless communication space-frequency coding frequency-selective fading channels multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems

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Rate 1 space-time and space-frequency spreading diversity technique

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TURKISH JOURNAL OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCES 2011年第3期19卷 463-482页

作者： Hacioglu, Gokce Gangal, Ali Karadeniz Tech Univ Dept Elect & Elect Engn Trabzon Turkey

In this study, a rate 1 transmitter diversity technique is proposed. The proposed technique uses spreading transform and space-time block coding (STBC) together. space-time, space-frequency, and frequency diversity applications of the proposed technique are shown. The code matrix of the proposed technique can be designed systematically. The proposed technique needs the channel coefficients to stay constant over transmission of 2 rows of the coding matrix regardless of the size of the coding matrix or the diversity order. However, joint detection of the symbols is required for the proposed technique. We used computer simulations to compare our technique with the quasi-orthogonal space-time block coding (QOSTBC), orthogonal space-time block coding (OSTBC), and spreading transform diversity methods. The results showed that the proposed technique provides higher SNR-BER gain than OSTBC and spreading transform diversity, and can provide a higher gain than QOSTBC for time-varying channels. The proposed technique is less sensitive to the time selectivity of the channel than QOSTBC or OSTBC. The detection complexity of the proposed technique is lower than that of spreading diversity.

关键词： Diversity space-time coding space-frequency coding carrier spreading OFDM

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A frequency Domain Pre-Equalizer for MIMO-OFDM Mobile Communication Systems Employing Alamouti coding

A Frequency Domain Pre-Equalizer for MIMO-OFDM Mobile Commun...

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12th IEEE International Workshop on Signal Processing Advances in Wireless Communications

作者： Baracca, P. Benvenuto, N. Vangelista, L. Univ Padua Dept Informat Engn I-35100 Padua Italy

ISBN: (纸本)9781424493326

Orthogonal frequency division multiplexing (OFDM) is a very popular modulation scheme because it requires a very simple receiver in transforming a frequency-selective channel into multiple flat-fading channels. Furthermore, multiple-input-multiple-output (MIMO) OFDM systems employing transmit diversity techniques, such as space-time (ST) and space-frequency (SF) coding, increase robustness and reliability over wireless fading channels. However, time-variation of the channel due to mobility disrupts orthogonality among subcarriers and yields intercarrier interference (ICI), limiting the performance of OFDM. In this paper we first recall a reduced-complexity technique to mitigate ICI in single-input-single-output (SISO) OFDM systems denoted per sub-block equalization (PSE) which operates on sub-blocks of the received OFDM symbol. Next we propose an extension of PSE to MIMO SF-OFDM systems. In particular, the Alamouti scheme is used in conjunction with PSE to combat ICI. Performance of the proposed scheme is evaluated for mobile digital video broadcasting DVB-T2 2 x 1 and 2 x 2 MIMO scenarios that suit with a possible extension to handheld devices in a next generation DVB-H. Numerical results show that the new receiver provides a gain from 21% to 33% with respect to the conventional OFDM receiver in terms of vehicular speed at which a target bit error rate can be maintained.

关键词： Alamouti coding Bit error rate Decoding Digital video broadcasting ICI MIMO MIMO communication MIMO-OFDM mobile communication system OFDM OFDM modulation PSE Receiving antennas SF SISO ST bit error rate digital video broadcasting digital video broadcasting DVB-T2 diversity reception diversity techniques equalisers error statistics fading channels frequency domain preequalizer intercarrier interference intercarrier interference interference suppression mobile communication multiple flat-fading channels multiple-input-multiple-output systems orthogonal frequency division multiplexing per subblock equalization reduced-complexity technique single-input- single-output space-frequency coding space-time coding

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Performance of SFBC-OFDM System with Pilot Aided Channel Estimation

Performance of SFBC-OFDM System with Pilot Aided Channel Est...

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7th IEEE International Wireless Communications and Mobile Computing Conference (IWCMC)

作者： Delestre, Fabien Sun, Yichuang Univ Hertfordshire Sch Engn & Technol Hatfield AL10 9AB Herts England

ISBN: (纸本)9781424495375

This paper introduces a computationally efficient pilot aided channel estimation method for space-frequency block coding (SFBC) Orthogonal frequency Division Multiplexing (OFDM) systems under frequency selective channels. The proposed method, simulated under WiMax requirements, is based on the use of eight pilots defined in the standard to estimate the channel parameters at constant interval. The pilots are also coded in the same SFBC format to simplify the estimation computations, but can be modulated by different modulation scheme to reduce the estimation error. The method offers tradeoff between accurate channel estimation and efficient bandwidth usage as more pilots would allow the algorithm to perform a more accurate estimation but at the cost of less transmitted data. Performances are evaluated for high mobility applications and with pilots modulated using different modulation schemes. Simulation results are presented for different number of antenna at the receiver, different values of Doppler shifts and different modulations for pilot and data subcarriers.

关键词： Orthogonal frequency Division Multiplexing (OFDM) Multiple Input Multiple Output (MIMO) WiMax Channel estimation space-frequency coding

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LDPC based differential unitary space-frequency coding for MIMO-OFDM systems

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2005年第6期6卷 294-298页

作者：姜海宁罗汉文田继锋宋文涛刘兴钊 Department of Electronic Engineering Shanghai Jiaotong University Shanghai 200030 China

This paper proposes a novel LDPC based differential unitary space-frequency coding (DUSFC) scheme for MIMO-OFDM systems when neither the transmitter nor the receiver has access to the channel state information (CSI). The new DUSFC strategy basically consists of coding across transmit antennas and OFDM tones simultaneously as well as differential modulation in the time-domain. It can fully exploit the inherent advantages provided by the multipath fading channels, resulting in a high degree of diversity. The state-of-the-art low-density parity-check (LDPC) codes are concatenated with our DUSFC as channel coding to improve the bit error rate (BER) performance considerably. Owing to the maximum multipath diversity and large coding advantages, LDPC-DUSFC strongly outperforms the differential unitary space-time coded OFDM techniques re- cently proposed in literature. The corresponding iterative decoding algorithm without channel estimation is finally provided to offer significant performance gain. Simulation results illustrate the merits of the proposed scheme.

关键词： Differential modulation Unitary space-time codes space-frequency coding MIMO OFDM LDPC

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