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Trigonometric transforms and precoding strategies for OFDM-based uplink hybrid multi-carrier nonorthogonal multiple access

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TRANSACTIONS ON EMERGING TELECOMMUNICATIONS TECHNOLOGIES 2019年第12期30卷 n/a-n/a页

作者： Trivedi, Vinay Kumar Ramadan, Khaled Kumar, Preetam Dessouky, Moawad Ibrahim Abd El-Samie, Fathi E. Indian Inst Technol Patna Dept Elect Engn Patna 801106 Bihar India Higher Inst Engn Al Shorouk Dept Elect & Elect Commun Engn Cairo Egypt Menoufia Univ Fac Elect Engn Dept Elect & Elect Commun Engn Menoufia Egypt

An uplink hybrid nonorthogonal multiple access (h-NOMA) scheme utilizing power domain multiplexing is adopted in this paper for orthogonal frequency-division multiplexing (OFDM)-based systems. The OFDM-based NOMA systems can achieve high spectral efficiency with resilience to wireless multipath fading. The h-NOMA maintains a low interference level per resource block or low complexity of multiuser detection (MUD) implementation at the receiver and also achieves consistent fairness performance by restricting the maximum number of users per resource block. An improved user clustering algorithm for OFDM-based h-NOMA system under the assumption of user's distinct data rate requirement is presented here. The proposed algorithm takes into consideration both the channel gain of all activated users and the different data rate requirements of weak channel gain users. High peak-to-average power ratio (PAPR) and performance degradation due to strict frequency synchronization requirements are the main drawbacks of such an OFDM-based uplink h-NOMA system. High PAPR of multicarrier NOMA is addressed here with precoding techniques. An enhanced minimum mean square error (MMSE) receiver performing joint equalization and carrier frequency offset (CFO) compensation using low-complexity banded-matrix implementation is proposed to cancel interference in the frequency domain. The MUD is implemented with low-complexity successive interference cancellation (SIC) using bandedmatrix approximation of the interference matrix in the presence of CFO. Moreover, the possibility of utilizing efficient trigonometric transforms to implement OFDM-based NOMA is studied with CFO and estimation errors. For OFDM-based h-NOMA system, an efficient combination of different trigonometric transform configurations to constitute the multicarrier basis for OFDM with a suitable precoding strategy for PAPR reduction is studied.

关键词： Orthogonal frequency division multiplexing Data transfer rates up link prediction coding multiple access non-orthogonal carrier frequency offset Transform spectral efficiency frequency synchronization Trigonometry Peak to average power ratio order of interference

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A string matching based ultra-low complexity lossless screen content coding technique

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MULTIMEDIA TOOLS AND APPLICATIONS 2022年第2期81卷 2043-2063页

作者： Yang, Yufen Lin, Tao Zhao, Liping Zhou, Kailun Wang, Shuhui Tongji Univ Coll Elect & Informat Engn VLSI Lab Shanghai 200092 Peoples R China Shaoxing Univ Dept Comp Sci & Engn Shaoxing 312000 Peoples R China Peking Univ Informat Technol R&D Innovat Ctr Shaoxing 312000 Peoples R China

Screen contents have become a popular image type driven by the growing market for transferring display screen between devices, especially mobile devices. Due to the ultra-high quality display featured in most of nowadays mobile devices, lossless screen content coding (SCC) is usually required or preferred. Mobile devices also require ultra-low power consumption in all tasks including SCC. To address these issues, this paper proposes an ultra-low coding complexity technique based on string matching for high efficiency lossless SCC. The technique covers three major coding phases of fast searching, prediction, and entropy coding. Condensed hash table (CHT) based fast searching is proposed to speed-up reference string searching process. Coplanar prediction (CP) and predictor-dependent residual (PDR) are presented to first efficiently predict an unmatchable pixel using multiple neighboring pixels and then further reduce the entropy of prediction residuals. To achieve a good trade-off between coding complexity and efficiency, 4-bit-aligned variable length code (4bVLC) and byte-aligned multi-variable-length-code (BMVLC) are proposed to code the prediction residuals and three string matching parameters, respectively. For 184 screen content images commonly used, compared with X265 and PNG in the default configuration and lossless mode, the proposed technique achieves 35.67% less total compressed bytes with only 0.96% encoding and 1.54% decoding runtime, and 10.04% less total compressed bytes with only 6.83% encoding and 24.32% decoding runtime, respectively. The proposed technique also outperforms X265 and PNG in all other configurations. For twelve HEVC-SCC CTC images, compared with PNG in fast, default and slow configurations and X265 in ultrafast and default configurations, the proposed technique shows significant advantage with both high coding efficiency and ultra-low coding complexity.

关键词： Screen content coding String matching prediction coding Variable length code Hash table

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High rate open-loop MIMO multi-user downlink transmission scheme based on blind precoding quasi-orthogonal space time block code

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IET COMMUNICATIONS 2009年第11期3卷 1757-1768页

作者： Han, Y. Ting, S. H. Guan, Y. L. Nanyang Technol Univ Sch Elect & Elect Engn Singapore 639798 Singapore

The authors first propose a new class of full-rate full-diversity quasi-orthogonal space time block code (QO-STBC), namely QO-STBC with blind precoding (BP-QO-STBC). Based on this code, a novel open-loop multiple-input multiple-output (MIMO) multi-user downlink transmission scheme is derived. Presuming M blocks of BP-QO-STBC (which could be of different code lengths) are transmitted from the access point simultaneously, thus achieving a multiplexing gain of M, we show that the multiplexed signal can be separated by any user with only m(R) >= M receive antennas, which is much smaller than that required by conventional linear schemes. The proposed scheme is extendable by simple iterative construction to an arbitrary number of transmit antennas. By exploiting the special structure of BP-QO-STBC, we derived two decoding algorithms with different levels of complexities, namely an optimal maximum likelihood decoder that achieves the lowest decoding complexity known for all full-rate full-diversity QO-STBC and a suboptimal linear decoder with even lower complexity. These two decoders combined with the simple construction method of BP-QO-STBC provide flexible tradeoffs between complexity and performance, as well as between diversity and multiplexing gains. A comparison between the proposed scheme and random beamforming in terms of bit error rate and achievable sum throughput is shown via simulation, and the results support our proposed scheme as a better practical candidate for high-speed wireless network.

关键词： Scheme downlinking prediction coding decoders Special structures multiple input multiple output systems EXPANDABLE transmitting antennas quasi-orthogonal MULTIPLEXOR Construction methods code length Codes MOMENT MAGNITUDE

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Transmitter preceding in synchronous multiuser communications

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IEEE TRANSACTIONS ON COMMUNICATIONS 1998年第10期46卷 1346-1355页

作者： Vojcic, BR Jang, WM George Washington Univ Dept Elect Engn & Comp Sci Washington DC 20052 USA

In this paper a synchronous multiuser system operating in an additive white Gaussian noise channel, with or without multipath fading, is considered. It is shown that when either a conventional single user receiver or the RAKE receiver is employed, both multiple access and intersymbol interference can be eliminated by means of a suitable transmitter preceding scheme, Transmitter preceding represents a linear transformation of transmitted signals, such that the mean squared errors at all receivers are minimized. Preceding, with both conventional single user receiver and with the RAKE receiver, results in near-far resistant performance and outperforms considerably the respective schemes without preceding. The crucial assumption, in the multipath case, is that the transmitter knows the multipath characteristics of all channels and that channel dynamics are sufficiently slow so that multipath profiles remain essentially constant over the block of preceded bits.

关键词： prediction coding linear transformations multiple access RAKE receivers Transmitter Multi access systems Receivers Multipath fading intersymbolic interference AWGN channels single user

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Predictive Processes and the Peculiar Case of Music

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TRENDS IN COGNITIVE SCIENCES 2019年第1期23卷 63-77页

作者： Koelsch, Stefan Vuust, Peter Friston, Karl Univ Bergen Dept Biol & Med Psychol Bergen Norway Aarhus Univ Ctr Mus Brain Dept Clin Med Aarhus Denmark Royal Acad Mus Aarhus Aalborg Aalborg Denmark UCL Wellcome Ctr Human Neuroimaging London England

We suggest that music perception is an active act of listening, providing an irresistible epistemic offering. When listening to music we constantly generate plausible hypotheses about what could happen next, while actively attending to music resolves the ensuing uncertainty. Within the predictive coding framework, we present a novel formulation of precision filtering and attentional selection, which explains why some lower-level auditory, and even higher-level music-syntactic processes elicited by irregular events are relatively exempt from top-down predictive processes. We review findings providing unique evidence for the attentional selection of salient auditory features. This formulation suggests that 'listening' is a more active process than traditionally conceived in models of perception.

关键词： Music Perception prediction coding Predictive senses Perception Music

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CB-REFIM: a practical coordinated beamforming in multicell networks

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IET COMMUNICATIONS 2014年第12期8卷 2131-2141页

作者： Akbari, Mohammad Hossein Vakili, Vahid Tabataba Iran Univ Sci & Technol Dept Elect Engn Tehran Iran

Performance of multicell systems is inevitably limited by interference and available resources. Although intercell interference can be mitigated by base station (BS) coordination, the demand on inter-BS information exchange and computational complexity grows rapidly with the number of cells, subcarriers and users. On the other hand, some of the existing coordination beamforming methods need computation of pseudo-inverse or generalised eigenvector of a matrix, which are practically difficult to implement in a real system. To handle these issues, the authors propose a novel linear beamforming across a set of coordinated cells only with limiting backhaul signalling. Resource allocation (i.e. precoding and power control) is formulated as an optimisation problem with objective function of signal-to-interference-plus-noise ratios in order to maximise the instantaneous weighted sum-rate subject to power constraints. Although the primal problem is non-convex and difficult to be optimally solved, an iterative algorithm is presented based on the Karush-Kuhn-Tucker condition. To have a practical solution with low computational complexity and signalling overhead, they present CB-REFIM (coordination beamforming-reference based interference management) and show the recently proposed reference based interference management algorithm (REFIM) can be interpreted as a special case of CB-REFIM. They evaluate CB-REFIM through extensive simulation and observe that the proposed strategies achieve close-to-optimal performance.

关键词： Non-Convex prediction coding Resource utilization Power control Objective function multicell complexity classes Beamforming Iterative algorithms inter-cell interference

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DATA-COMPRESSION OF STEREOPAIRS

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IEEE TRANSACTIONS ON COMMUNICATIONS 1992年第4期40卷 684-696页

作者： PERKINS, MG Institute for Communications Technology German AeroSpace Research Establishment (DLR) Oberpfaffenhofen Germany

This paper addresses the problem of stereopair data compression. Two fundamentally different techniques for compressing stereopairs are discussed. The first technique, called disparity-compensated transform-domain predictive coding, attempts to minimize the mean-square error between the original stereopair and the compressed stereopair. The second technique, called mixed-resolution coding, is a psychophysically justified technique that exploits known facts about human stereovision to code stereopairs in a subjectively acceptable manner. A method for assessing the quality of compressed stereopairs is also presented. It involves measuring the ability of an observer to perceive depth in coded stereopairs. We found that observers generally perceived objects to be further away in compressed stereopairs than they did in originals. Finally, the problem of coding stereopairs is considered from a rate-distortion perspective. It is proved that the rate distortion limit for coding stereopairs cannot in general be achieved by a coder that first codes and decodes the right picture sequence independently of the left picture sequence, and then codes and decodes the left picture sequence given the decoded right picture sequence.

关键词： Rate distortion prediction coding picture COMPRESSED Observers DEcoding ENCODER Codes coding

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Time-interpolated channel estimation for increasing channel capacity of superimposed training-based precoding schemes

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IET COMMUNICATIONS 2015年第7期9卷 933-939页

作者： Kim, Byung Wook Jung, Sung-Yoon Kyungil Univ Sch Elect & Railway Engn Gyongsan 712701 Gyeongbuk South Korea Yeungnam Univ Dept Elect Engn Gyongsan 712749 Gyeongbuk South Korea

This study proposes a time-interpolated channel estimation method for the superimposed training-based precoding scheme in slowly time-varying channels. The regular inclusion of a superimposed training sequence, which is necessary for explicit time-varying channel estimation, reduces the power allocated to information transmission. Therefore time-interpolated channel estimation, where the transmission without a superimposed training symbol is performed during a few coherence times, makes very efficient use of transmitting power and possible gains in terms of capacity. A closed-form solution of the periodicity of time-interpolated channel estimation was derived using this method together with a Markov channel model. The simulation results confirmed that the use of the time-interpolated channel estimation method improves the performance of channel capacity and possibly provides energy savings for mobile terminals.

关键词： channel model time-varying channels channel estimation data transmission Channel capacity Transmitter power prediction coding mobile terminal energy saving

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Hardware designs and analysis for variant receive space modulation techniques

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TRANSACTIONS ON EMERGING TELECOMMUNICATIONS TECHNOLOGIES 2018年第12期29卷 e3545-e3545页

作者： Hiari, Omar Mesleh, Raed German Jordanian Univ Dept Comp Engn Sch Elect Engn & Informat Technol Amman 11180 Jordan German Jordanian Univ Dept Elect & Commun Engn Sch Elect Engn & Informat Technol Amman Jordan

Hardware designs for variant receive space modulation techniques (RSMTs) containing a reduced number of hardware components are proposed in this study. RSMTs rely on precoding of transmitted signals through channel knowledge at the transmitter to spatially modulate the receive antennas. As such, certain receive antennas will only receive messages while all other antennas will not receive any signal. It has been debated in literature that different RSMTs can be designed with single radio frequency (RF) chain receiver. Yet, practical designs are not yet available in literature. In this paper, a family of receiver designs for RSMTs based on commercial off-the-shelf components (COTS) are proposed and analyzed. Average error probability, power consumption, cost, and receiver complexity of the different techniques are presented and discussed. Additionally, Simulink models for all these systems are developed and presented. It is revealed that all RSMTs, in fact, do not require more than a single RF chain receiver or in some cases no RF chain, just by utilizing COTS components.

关键词： radiofrequency variants Receiving antennas prediction coding Computer hardware Messages Receivers

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An Algorithm for Simple Differential Speech coding Based on Backward Adaptation Technique

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INFORMATICA 2018年第3期29卷 539-553页

作者： Tomic, Stefan S. Peric, Zoran H. Nikolic, Jelena R. Univ Nis Fac Elect Engn Aleksandra Medvedeva 14 Nish Serbia

This paper presents a simple differential speech signal coding algorithm, based on backward adaptation. The considered algorithm is executed in frame by frame manner, by implementing predictive and adaptive quantization techniques. Both prediction and adaptation are performed backward, based on the previously quantized input signal frame. This enables us to obtain high quality output signal, without increasing the bit rate. This research puts emphasis on the quantizer design, with the optimal support limit determination, and theoretical performance evaluation. Objective quality of the output signal is evaluated through signal to quantization noise ratio (SQNR). We perform theoretical and experimental analysis of the algorithm performance and provide comparative results of implementing speech signal coding techniques with similar complexity. Experimental results show that our simple differential speech coding algorithm satisfies the G. 712 Recommendation for high-quality speech coding at the bit rate of 6 bits per sample. This indicates that the algorithm can be successfully implemented in high quality speech signal coding.

关键词： speech coding algorithm backward adaptive technique prediction coding differential coding

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