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Decimation Double-Phase Estimator: An Efficient and Unambiguous High-Order Binary Offset Carrier Tracking Algorithm

IEEE SIGNAL PROCESSING LETTERS 2016年第7期23卷 905-909页

作者： Feng, Tian Natl Univ Def Technol Changsha 410073 Hunan Peoples R China

Traditional binary offset carrier (BOC) tracking algorithms process the upper and lower sideband signals together, and thus, the sampling frequency and computational requirements are much higher than that required for binary phase-shift keying tracking algorithms, especially for high-order BOC signals. Addressing existing limitations, this letter proposes a decimation double-phase estimator (DDPE) tracking algorithm for BOC signals. The algorithm uses a normal carrier and a subcarrier with a constant frequency to shift the upper and lower sideband signals of BOC to the zero frequency and decimates the signal before processing by the correlator. The residual carrier and the subcarrier are then tracked by the double-phase estimator algorithm. Decimating the signals significantly reduces the computational complexity, and for a BOC(6n, n) signal, the DDPE is found to reduce 86% of correlator operations with a signal-to-noise ratio loss of 0.5 dB.

关键词： Binary offset carrier (BOC) signal decimation double-phase estimator (DDPE) low computational complexity unambiguous tracking

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A modified SLM scheme with low complexity for PAPR reduction of OFDM systems

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IEEE TRANSACTIONS ON BROADCASTING 2007年第4期53卷 804-808页

作者： Heo, Seok-Joong Noh, Hyung-Suk No, Jong-Seon Shin, Dong-Joon Hanyang Univ Div Elect & Comp Engn Seoul 133791 South Korea Seoul Natl Univ Dept Elect Engn & Comp Sci Seoul 151744 South Korea

In this paper, we propose a new peak-to-average power ratio (PAPR) reduction scheme of orthogonal frequency division multiplexing (OFDM) system, called a modified selected mapping (SLM) scheme, which considerably reduces the computational complexity with keeping the similar PAPR reduction performance compared with the conventional SLM scheme. The proposed scheme is analytically and numerically evaluated for the OFDM system specified in the IEEE 802.16 standard. For the OFDM system with 2048 subcarriers, the proposed scheme with 4 binary phase sequences can reduce the complex multiplications by 63.5% with the similar PAPR reduction compared with the SLM scheme with 16 binary phase sequences.

关键词： low computational complexity orthogonal frequency division multiplexing (OFDM) peak-to-average power ratio (PAPR) selected mapping (SLM)

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Robust optimisation of source power and relay beamforming in multiuser wireless networks

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IET COMMUNICATIONS 2019年第19期13卷 3302-3306页

作者： Rashid, Umar Sarwar, Muqaddas Awan, Fahim Univ Engn & Technol Dept Elect Engn KSK Campus Lahore Pakistan

In this work, a novel design for a highly non-convex problem of joint optimisation of source power and relay beamforming vector in multi-user systems is presented. Taking into account imperfect channel-state information, the design problem is formulated as a non-convex optimisation problem for the maximisation of the minimum signal-to-interference-plus-noise ratio across given users. This computationally-intractable non-convex problem is exploited for hidden convexity after which a path-following algorithm with low computational complexity is developed which converges to a local optimal point after a few iterations. Extensive simulation results show that the proposed algorithm of joint design outperforms the alternating optimisations of source power and relay beamforming.

关键词： optimisation array signal processing computational complexity iterative methods multiuser channels relay networks (telecommunication) wireless channels hidden convexity low computational complexity source power robust optimisation multiuser wireless networks joint optimisation relay beamforming vector multiuser systems nonconvex optimisation problem minimum signal-to-interference-plus-noise ratio imperfect channel-state information path-following algorithm computationally-intractable nonconvex problem

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An Efficient Gauss-Seidel Cubature Kalman Filter

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS 2022年第3期69卷 1932-1936页

作者： Meng, Qingwen Li, Xuyou Guo, Yanda Harbin Engn Univ Coll Intelligent Syst Sci & Engn Harbin 150001 Peoples R China

The Cubature Kalman filter (CKF) is a widely used filter with excellent performance, particularly on large non-linear systems. However, the CKF is computationally challenging to implement. The matrix inversion operation increases the computational burden if exact inversion methods, such as the Cholesky decomposition, are used. To reduce the CKF computational cost without losing accuracy in non-linear systems, in this study, we propose an efficient CKF, called the Gauss-Seidel Cubature Kalman filter (GSCKF), where the traditional Kalman gain calculating operation is replaced with the Gauss-Seidel (GS) method. The GS method is exploited to calculate the Kalman gain without complicated matrix inversion. To choose the optimal number of iterations adaptively, the Euclidean norm is considered as the evaluation criterion, which helps the GSCKF achieve the accuracy similar to CKF with less complexity. The computational complexity analysis and execution time results reveal that the GSCKF computational cost is significantly reduced. Numerical simulation results on different large non-linear systems show that the GSCKF, with only a few iterations and outstanding time efficiency, can provide a performance that is indistinguishable with respect to the performance of the CKF. The proposed algorithm will be useful in a variety of engineering areas, specifically in signal processing issues involving large non-linear systems.

关键词： Kalman filters computational efficiency Covariance matrices Mathematical models Jacobian matrices Iterative methods Symmetric matrices Gauss-Seidel iterations cubature Kalman filter low computational complexity large systems non-linear estimation

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Real-time epileptic seizure prediction based on online monitoring of pre-ictal features

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MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING 2019年第11期57卷 2461-2469页

作者： Sadeghzadeh, Hoda Hosseini-Nejad, Hossein Salehi, Sina KN Toosi Univ Technol Fac Comp Engn Tehran Iran KN Toosi Univ Technol Fac Elect Engn POB 16315-1355 Tehran *** Iran Shiraz Univ Med Sci Shiraz Neurosci Res Ctr Shiraz Iran

Reliable prediction of epileptic seizures is of prime importance as it can drastically change the quality of life for patients. This study aims to propose a real-time low computational approach for the prediction of epileptic seizures and to present an efficient hardware implementation of this approach for portable prediction systems. Three levels of feature extraction are performed to characterize the pre-ictal activities of the EEG signal. In the first-level, the line length algorithm is applied to the pre-ictal region. The features obtained in the first-level are mathematically integrated to extract the second-level features and then the line lengths of the second-level features are calculated to obtain our third-level feature. The third-level information is compared with predefined threshold levels to make a decision on whether the extracted characteristics are relevant to a seizure occurrence or not. The validity of this algorithm was tested by EEG recordings in the CHB-MIT database (97 seizures, 834.224 h) for 19 epileptic patients. The results showed that the average sensitivity was 90.62%, the specificity was 88.34%, the accuracy was 88.76% with the average false prediction rate as low as 0.0046 h(-1), and the average prediction time was 23.3 min. The low computational complexity is the superiority of the proposed approach, which provides a technologically simple but accurate way of predicting epileptic seizures and enables hardware implantable devices.

关键词： Epileptic seizure prediction EEG low computational complexity Hardware implementation Line length

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low-PAPR Layered/Enhanced ACO-SCFDM for Optical-Wireless Communications

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IEEE PHOTONICS TECHNOLOGY LETTERS 2018年第2期30卷 165-168页

作者： Zhou, Ji Wang, Qi Cheng, Qixiang Guo, Mengqi Lu, Yueming Yang, Aiying Qiao, Yaojun Beijing Univ Posts & Telecommun Sch Informat & Commun Engn State Key Lab Informat Photon & Opt Commun Beijing 100876 Peoples R China Columbia Univ Dept Elect Engn New York NY 10026 USA Univ Southampton Dept Elect & Comp Sci Southampton SO17 1BJ Hants England Beijing Inst Technol Sch Optoelect Beijing 100081 Peoples R China

In this letter, we propose layered/enhanced asymmetrically clipped optical single-carrier frequency-division multiplexing (L/E-ACO-SCFDM) for optical-wireless communications. L/E-ACO-SCFDMhas a lower computational complexity and peak-to-average power ratio (PAPR) than L/E-ACO orthogonal frequency-division multiplexing (L/E-ACO-OFDM). The computational complexity of the simplified transmitter in L/E-ACO-SCFDM with R layers is (2 -2/2(R)) O(N), which is lower than the computational complexity of (2 -2/2(R)) O(Nlog(2)N) in L/E-ACO-OFDM. At a complementary cumulative distribution function of 10(-3), the PAPR of L/E-ACO-SCFDM is approximately 4.2, 3.4, and 2.7 dB lower than that of L/E-ACO-OFDM for 2, 3, and 4 layers, respectively. The simulation results indicate that L/E-ACO-SCFDM has better performance than L/E-ACO-OFDM under the transmitter nonlinearity and multipath fading.

关键词： low PAPR low computational complexity layered/enhanced ACO-SCFDM optical-wireless communications

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Highly Doppler-tolerant pulsed waveform

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ELECTRONICS LETTERS 2020年第21期56卷 1133-+页

作者： McCargar, R. K. Storm, S. D. Smith, G. E. Garry, J. L. Johns Hopkins Univ Appl Phys Lab Laurel MD 21218 USA George Washington Univ Washington DC USA

This Letter describes a pulsed waveform which exhibits extreme Doppler tolerance, enabling large time-bandwidth-product observations of high-velocity targets with low computational complexity. The waveform, which supports pulsewidth, pulse repetition interval, and frequency agility, utilises hyperbolic frequency-modulated pulses with modulation parameters constrained to suppress range migration.

关键词： radar signal processing Doppler radar computational complexity frequency modulation highly Doppler-tolerant pulsed waveform extreme Doppler tolerance time-bandwidth-product observations high-velocity targets low computational complexity pulse repetition interval hyperbolic frequency-modulated pulses

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Sparse Code Multiple Access Decoding Based on a Monte Carlo Markov Chain Method

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IEEE SIGNAL PROCESSING LETTERS 2016年第5期23卷 639-643页

作者： Chen, Jienan Zhang, Zhenbing He, Shuaining Hu, Jianhao Sobelman, Gerald E. Univ Elect Sci & Technol China Natl Key Lab Sci & Technol Commun Chengdu 611731 Peoples R China Univ Minnesota Dept Elect & Comp Engn Minneapolis MN 55455 USA

Nonorthogonal multiple access technology has been proposed for use in 5G communications systems. In particular, the sparse code multiple access (SCMA) scheme is believed to be one of the most promising techniques among the various nonorthogonal approaches that have been investigated. In this letter, we focus on reducing the complexity of SCMA decoding and we propose a Monte Carlo Markov Chain (MCMC) based SCMA decoder. Benefiting from the linearly increasing complexity of the MCMC method, the proposed SCMA decoder has only 10% of the computational load compared to previous state-of-the-art methods when the codebook size is 64. Consequently, the MCMC SCMA decoder has great potential for use in practical system implementations.

关键词： low computational complexity Monte Carlo Markov Chain (MCMC) nonorthogonal multiple access sparse code multiple access (SCMA)

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Optimized Layered/Enhanced ACO-SCFDM for Short-Reach Optical Interconnects

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IEEE PHOTONICS TECHNOLOGY LETTERS 2018年第14期30卷 1321-1324页

作者： Guo, Mengqi Zhou, Ji Tang, Xizi Qi, Jia Liu, Shuangyue Xu, Xuekai Lu, Yueming Qiao, Yaojun Beijing Univ Posts & Telecommun Sch Informat & Commun Engn State Key Lab Informat Photon & Opt Commun Beijing 100876 Peoples R China Beijing Univ Posts & Telecommun Minist Educ Key Lab Trustworthy Distributed Comp & Serv Beijing 100876 Peoples R China

This letter is the first experimental demonstration of layered/enhanced asymmetrically clipped optical single-carrier frequency-division multiplexing (L/E-ACO-SCFDM) in short-reach optical interconnects. An optimized method is employed to significantly improve the performance of L/E-ACO-SCFDM. L/E-ACO-SCFDM has higher spectral efficiency than ACO-SCFDM, and it also has lower peak-to-average power ratio and computational complexity than L/E-ACO orthogonal frequency-division multiplexing (L/E-ACO-OFDM). In the experimental system, the low-cost electrical and optical devices are utilized, which induce serious high-frequency distortion caused by bandwidth limitation. Under the same spectral efficiency and net bit rate, the optimized L/E-ACO-SCFDM has about 4-dB and more than 3-dB receive sensitivity improvement at 7% forward error correction limit compared with the optimized L/E-ACO-OFDM and the optimized ACO-SCFDM, respectively. Therefore, L/E-ACO-SCFDM is a promising scheme for the future short-reach optical interconnects.

关键词： L/E-ACO-SCFDM low peak-to-average power ratio low computational complexity optical interconnects

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Fast Delay-Multiply-and-Sum Beamformer: Application to Confocal Microwave Imaging

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IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS 2020年第1期19卷 14-18页

作者： KaramFard, SeyedAbbas SeyedShah Asl, Babak Mohammadzadeh Tarbiat Modares Univ Dept Biomed Engn Tehran 14115111 Iran

Confocal microwave imaging is a promising medical imaging method in which the quality and the speed of imaging depend on the used beamformer. The delay-multiply-and-sum (DMAS) is a potential alternative to the golden standard method delay-and-sum (DAS). The advantages of DMAS over DAS and some other common beamformers, e.g., finer resolution and higher contrast, have been demonstrated through many papers, and the main disadvantage of this method is its high computational complexity. This letter introduces fast DMAS (FDMAS) method, which offers the same linear computational complexity as DAS while maintaining the output similar to DMAS. FDMAS computes the output of DMAS using the first and the second moments of the observations. This letter mathematically proves the equality between the proposed method and DMAS, and also demonstrates the equality of these methods' results using real random values and experimental complex data. Moreover, the lower computational load order of the proposed method in comparison to the DMAS is shown. As a conclusion, the FDMAS technique provides the advantages of DMAS without encountering the computational complexity issue. It is noteworthy that the FDMAS is an iterative method and thereby can update the results by adding new observations without carrying out any unnecessary computations.

关键词： Beamformer delay-multiply-and-sum (DMAS) fast DMAS (FDMAS) linear computational load low computational complexity

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