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QOSTBC coded MIMO system with reduced complexity and optimised decoding for rank deficient channels

IET COMMUNICATIONS 2020年第4期14卷 646-654页

作者： Gupta, Bhasker Balyan, Vipin Saini, Davinder S. CCET ECE Dept Sect 26 Chandigarh India Cape Peninsula Univ Technol EEC Dept Cape Town South Africa

In multiple-input multiple-output (MIMO) systems, rank deficient channels are the most common and key areas of research. In these channels, the number of transmit antennas (M-Tx) is higher than receive antennas (M-Rx) and subsequently the unknown variables are more than the number of equations. In such situations, the conventional sphere decoder (SD) fails due to the presence of zero diagonal elements in Cholesky decomposition. This study analyses the quasi-orthogonal space-time block code (QOSTBC) of symbol rate-2 for M-Tx = 4 with modified double-layer SD detection to overcome rank deficiency problem. The first half of transmitted symbols is detected using two partially dependent SDs with optimised search radii. The remaining half is detected by employing single symbol maximum likelihood detection. Simulation and analytical results indicate that the proposed detection scheme reduces bit error rate and complexity compared to existing techniques.

关键词： channel coding space-time block codes maximum likelihood detection decoding transmitting antennas MIMO communication receiving antennas error statistics antenna arrays communication complexity search problems rank deficient channels multiple-input multiple-output systems transmitting antennas sphere decoder zero diagonal elements quasiorthogonal space-time block code symbol rate-2 modified double-layer SD detection rank deficiency problem single symbol maximum likelihood detection bit error rate QOSTBC coded MIMO system search radii optimisation receiving antennas Cholesky decomposition

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Subcarrier Intensity Modulated MIMO Optical Communications in Atmospheric Turbulence

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JOURNAL OF OPTICAL COMMUNICATIONS AND NETWORKING 2013年第9期5卷 1001-1009页

作者： Song, Xuegui Cheng, Julian Univ British Columbia Sch Engn Kelowna BC Canada

We investigate spatial diversity techniques for subcarrier phase-shift keying (PSK)-modulated optical wireless communication links over the Gamma-Gamma channels. Both repetition code and the Alamouti-type orthogonal space-time block code (OSTBC) are considered. Highly accurate series error rate expressions are derived by using a moment generating function approach with a series expansion of the modified Bessel function. Truncation error analyses and asymptotic error rate analyses are also presented. Our asymptotic analyses show that the diversity order of the studied system depends only on the effective number of small-scale cells of the scattering process in the atmosphere. Our performance analyses confirm that the repetition code outperforms OSTBC for subcarrier PSK-based systems over the Gamma-Gamma channels. The asymptotic performance loss of the Alamouti-coded system with respect to the repetition-coded system is also quantified analytically.

关键词： Alamouti code Atmospheric turbulence multiple-input multiple-output systems Optical wireless communication

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Parameterised codebook design based on channel statistics for efficient multi-rank MIMO transmission

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IET COMMUNICATIONS 2018年第15期12卷 1880-1890页

作者： Shin, Sungin Lee, Hyukjun Kim, Changhyeon Sung, Wonjin Park, Jonghyun Sogang Univ Dept Elect Engn Seoul 04107 South Korea LG Elect Adv Standard R&D Lab Seoul 07336 South Korea

As the number of antenna elements increases in multiple-input multiple-output (MIMO) systems, an efficient feedback and beamforming strategy becomes more important to achieve the desired bandwidth efficiency required by the next-generation wireless systems. The authors investigate the statistical characteristics of the MIMO channel generated by the three-dimensional spatial channel model to recognise some of the limitations inherent in the existing codebooks adopted by the current third generation partnership project specifications. Such limitations include unnecessary co-phasing combinations for cross-polarised (X-pol) antenna arrays and, in particular, long-term codevector selections, which are not best suited to the channel distributions. In this study, the observed shortcomings are improved by proposing a new multi-rank codebook applicable to the X-pol array of antenna elements supporting up to the quadruple rank. The proposed beamforming codevectors are presented using variable parameters so that they can be adapted to changing channel characteristics. The efficiency of the proposed codebook is further improved by eliminating redundant co-phasing values. The performance of the proposed codebook is evaluated using the TR 36.873 urban macro environment and its effectiveness is demonstrated by quantifying its gain over the existing codebooks.

关键词： MIMO communication wireless channels channel capacity array signal processing antenna arrays parameterised codebook design channel statistics efficient multirank MIMO transmission antenna elements increases multiple-input multiple-output systems channel state information beamforming strategy next-generation wireless systems statistical characteristics MIMO channel three-dimensional spatial channel model current third generation partnership project specifications unnecessary co-phasing combinations cross-polarised antenna arrays long-term codevector selections channel distributions X-pol array quadruple rank beamforming codevectors

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MIMO Multiway Relaying With Clustered Full Data Exchange: Signal Space Alignment and Degrees of Freedom

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2014年第12期13卷 6795-6808页

作者： Yuan, Xiaojun ShanghaiTech Univ Sch Informat Sci & Technol Shanghai 200031 Peoples R China

Recently, much research interest has been focused on the design of efficient communication mechanisms for multiple-input-multiple-output (MIMO) multiway relay channels (mRCs). In this paper, we investigate achievable degrees of freedom (DoFs) of the MIMO mRC with L clusters and K users per cluster, where each user is equipped with M antennas and the relay with N antennas. Our analysis is focused on a new data exchange model, termed clustered full data exchange, i.e., each user in a cluster wants to learn the messages of all the other users in the same cluster. Novel signal alignment techniques are developed to jointly and systematically construct the beamforming matrices at the users and the relay for efficient implementation of physical-layer network coding. Based on this, we derive an achievable DoF of the MIMO mRC with an arbitrary network configuration of L and K, as well as with an arbitrary antenna configuration of M and N. We show that our proposed scheme achieves the DoF capacity when M/N <= 1/(LK - 1) and M/N >= ((K - 1) L + 1)/KL. The DoF results derived in this paper can serve as fundamental benchmarks in evaluating the performance of practical communication systems over MIMO mRCs and provide guidance and insights into the design of wireless relay networks.

关键词： Multiway relay channels degrees of freedom multiple-input multiple-output systems physical-layer network coding signal and interference alignment

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A reconfigurable iterative algorithm for the K-user MIMO interference channel

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SIGNAL PROCESSING 2013年第12期93卷 3353-3362页

作者： Alexandropoulos, George C. Papadias, Constantinos B. AIT Athens 19002 Greece

Interference alignment (IA) is a recently proposed transmission technique for the K-user interference channel (IFC), which is proven to achieve a sum-rate multiplexing gain of K/2 at the high interference regime. Motivated by our recent work [1] that showed how the sum-rate scaling can range between K/2 and K for moderate-to-low interference conditions, in this paper we present a novel iterative algorithm for the K-user multiple-input multiple-output (MIMO) IFC with arbitrary number of transceiver antennas. The proposed algorithm automatically adjusts itself to the interference regime at hand, in the above sense, as well as to the wireless channel in order to achieve the appropriate sum-rate scaling. Our reconfigurable algorithm combines the system-wide mean squared error minimization criterion with the single-user waterfilling solution to maximize each user's transmission rate according to the interference levels and channel conditions. Extensive computer simulation results for the sum-rate performance of the proposed reconfigurable algorithm over various Ricean fading channels are presented. It is shown that, in the interference-limited regime, the proposed algorithm reconfigures itself so as to achieve the IA scaling whereas, in the moderate-to-low interference regime, it chooses interference-myopic MIMO transmissions for all K communication pairs. (c) 2013 Elsevier B.V. All rights reserved.

关键词： Interference alignment multiple-input multiple-output systems Multiuser communications Sum-rate performance Transceiver design

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Higher order statistics for modulation and STBC recognition in MIMO systems

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IET COMMUNICATIONS 2019年第16期13卷 2436-2446页

作者： Khosraviyani, Mokhtar Kalbkhani, Hashem Shayesteh, Mahrokh G. Urmia Univ Dept Elect Engn Orumiyeh Iran Urmia Univ Technol Fac Elect Engn Orumiyeh Iran Sharif Univ Technol Elec Engn Dept ACRI Wireless Res Lab Tehran Iran

Identification of modulation and space-time block code (STBC) is an important task of receivers in applications such as military, civilian, and commercial communications. Here, we consider multiple-input multiple-output (MIMO) systems. We propose two methods for STBC identification when the modulation is known. We also introduce a method for joint identification of code and modulation. Additionally, we present an enhanced zero-forcing (ZF) equaliser to improve the separation between the features of different classes. Higher order cumulants are used as the statistical features. In the first method of STBC identification, after the proposed equalisation, received data samples are segmented, and then using the mean and Frobenius norm of the covariance matrix of extracted cumulants as threshold values, the STBCs are detected. This method requires the knowledge of the threshold values for each modulation type and noise power. In the second method, the knowledge of noise power and the type of modulation are not needed. After the proposed ZF equalisation, feature vector based on the cumulants is calculated, and then support vector machine (SVM) classifier is used to classify different STBCs. In the third method, joint detection of STBC and modulation type is performed using the proposed ZF equaliser and mapping the received samples. This method deals with the theoretical values calculated from the cumulants of four STBCs and four modulations, where there is no need to know the noise power. The results indicate that the proposed methods perform well even at low signal-to-noise ratios (SNRs).

关键词： equalisers higher order statistics support vector machines covariance matrices MIMO communication space-time block codes pattern classification telecommunication computing higher order statistics STBC recognition MIMO systems space-time block code multiple-input multiple-output systems STBC identification joint identification higher order cumulants statistical features threshold values modulation type noise power feature vector joint detection ZF equaliser Frobenius norm support vector machine classifier zero-forcing equaliser covariance matrix SVM classifier signal-to-noise ratios

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Extended fully improved quadrature spatial shift keying modulation

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SIGNAL IMAGE AND VIDEO PROCESSING 2022年第3期16卷 783-788页

作者： Celik, Yasin Aldirmaz-Colak, Sultan Aksaray Univ Dept Elect & Elect Engn Aksaray Turkey Kocaeli Univ Dept Elect & Commun Engn Kocaeli Turkey

In this paper, extended fully improved quadrature space shift keying (EFIQSSK) modulation, which is a combination of extended quadrature spatial modulation (EQSM) scheme and fully improved quadrature space shift keying (FIQSSK), is proposed. EFIQSSK uses only antenna indices to modulate data bits, achieving a bit rate of four times the number of antennas per channel usage. The proposed scheme can be implemented with any number of antennas. It has a low complexity since it does not need any radio frequency (RF) chain on the transmitter side. In our study, the bit error rate performance of this technique is compared with the schemes in the literature with the same spectral efficiency. In addition, the transmission scheme used in the method has been optimized to provide low bit error. In the Monte Carlo simulations, it has been observed that the proposed scheme outperforms other schemes in the literature with the same spectral efficiency when using 3 or more transmit antennas.

关键词： Spatial modulation multiple-input multiple-output systems Spectral efficiency

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Full-Duplex Wireless for 6G: Progress Brings New Opportunities and Challenges

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2023年第9期41卷 2729-2750页

作者： Smida, Besma Sabharwal, Ashutosh Fodor, Gabor Alexandropoulos, George C. Suraweera, Himal A. Chae, Chan-Byoung Univ Illinois Dept Elect & Comp Engn Chicago IL 77005 USA Rice Univ Dept Elect & Comp Engn Houston TX 77005 USA Ericsson Res S-16480 Stockholm Sweden KTH Royal Inst Technol S-10044 Stockholm Sweden Natl & Kapodistrian Univ Athens Dept Informat & Telecommun Athens 15784 Greece Univ Peradeniya Dept Elect & Elect Engn Peradeniya 20400 Sri Lanka Yonsei Univ Sch Integrated Technol Seoul 03722 South Korea

The use of in-band full-duplex (FD) enables nodes to simultaneously transmit and receive on the same frequency band, which challenges the traditional assumption in wireless network design. The full-duplex capability enhances spectral efficiency and decreases latency, which are two key drivers pushing the performance expectations of next-generation mobile networks. In less than ten years, in-band FD has advanced from being demonstrated in research labs to being implemented in standards, presenting new opportunities to utilize its foundational concepts. Some of the most significant opportunities include using FD to enable wireless networks to sense the physical environment, integrate sensing and communication applications, develop integrated access and backhaul solutions, and work with smart signal propagation environments powered by reconfigurable intelligent surfaces. However, these new opportunities also come with new challenges for large-scale commercial deployment of FD technology, such as managing self-interference, combating cross-link interference in multi-cell networks, and coexistence of dynamic time division duplex, subband FD and FD networks.

关键词： Cross-link interference full-duplex self-interference cancellation localization integrated access and backhaul integrated sensing and communication multiple-input multiple-output systems reconfigurable intelligent surface non-terrestrial networks

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Blind Digital Modulation Identification for Spatially-Correlated MIMO systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2012年第2期11卷 683-693页

作者： Hassan, Kais Dayoub, Iyad Hamouda, Walaa Nzeza, Crepin Nsiala Berbineau, Marion Univ Lille Nord France F-59000 Lille France LEOST IFSTTAR F-59650 Villeneuve Dascq France DOAE IEMN F-59313 Valenciennes France Concordia Univ Montreal PQ H3G 1M8 Canada

Modulation type is one of the most important characteristics used in signal waveform identification and classification. Spatial correlation is a crucial factor for practical multiple-input multiple-output (MIMO) systems. This paper addresses the problem of blind digital modulation identification in spatially-correlated MIMO systems. The proposed algorithm is verified using higher order statistical moments and cumulants of the received signal. The purpose is to discriminate among different M-ary shift keying linear modulation schemes without any priori signal information. This study employs several MIMO techniques to identify the modulation with and without channel state information (CSI). The proposed classifier shows a high identification performance in acceptable signal-to-noise ratio (SNR) range.

关键词： Higher order statistics multiple-input multiple-output systems modulation identification spatial correlation

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A new sub-optimal decoder for quasi-orthogonal space-time block codes

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IEEE COMMUNICATIONS LETTERS 2008年第8期12卷 548-550页

作者： Leuschner, Jeff Yousefi, Shahram Queens Univ Signal Design & Anal Lab Dept Elect & Comp Engn Kingston ON K7L 3N6 Canada

This letter addresses the sub-optimal decoding of quasi-orthogonal space-time block codes. First, decoding using a simple linear receiver is considered in terms of the complexity versus error performance trade off. A new Chase-type suboptimal decoding algorithm is proposed using the inner products in the metric expression as reliability measures.

关键词： quasi-orthogonal space-time block codes maximum-likelihood decoding multiple-input multiple-output systems

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