In this paper, a triple-layer hybrid optical orthogonal frequency division multiplexing (THO-OFDM) for intensity modulation with direct detection (IM/DD) systems with a high spectral efficiency is proposed. We combine...
详细信息
In this paper, a triple-layer hybrid optical orthogonal frequency division multiplexing (THO-OFDM) for intensity modulation with direct detection (IM/DD) systems with a high spectral efficiency is proposed. We combine N-point asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM), N/2-point ACO-OFDM, and N/2-point pulse amplitude modulated discrete multitoned (PAM-DMT) in a single frame for simultaneous transmission. The time- and frequency-domain demodulation methods are introduced by fully exploiting the special structure of the proposed THO-OFDM. Theoretical analysis show that, the proposed THO-OFDM can reach the spectral efficiency limit of the conventional layered ACO-OFDM (LACO-OFDM). Simulation results demonstrate that, the time-domain receiver offers improved bit error rate (BER) performance compared with the frequency-domain with similar to 40% reduced computation complexity when using 512 subcarriers. Furthermore, we show a 3 dB improvement in the peak-to-average power ratio (PAPR) compared with LACO-OFDM for the same three layers.
Designing a key distribution protocol with minimal computation and storage complexity is a challenging issue in secure multimedia multicast. In most of the multimedia multicast applications, the group membership requi...
详细信息
Designing a key distribution protocol with minimal computation and storage complexity is a challenging issue in secure multimedia multicast. In most of the multimedia multicast applications, the group membership requires secured dynamic key generation and updation operations that usually consume much of the computation time. In this paper, we propose a new GCD (Greatest Common Divisor) based Key Distribution Protocol which focuses on two dimensions. The first dimension deals with the reduction of computation complexity which is achieved in our protocol by performing fewer multiplication operations during the key updation process. To optimize the number of multiplication operations, the existing Karatsuba divide and conquer approach for multiplication is used in this proposed work. The second dimension aims at reducing the amount of information stored in the Group Center and group members while performing the update operation in the key content. The proposed algorithm which focuses on these two dimensions has been implemented and tested using a Cluster tree based key management scheme and has been found to produce promising results. Comparative analysis to illustrate the performance of various key distribution protocols is shown in this paper and it has been observed that this proposed algorithm reduces the computation and storage complexity significantly. (c) 2012 Elsevier Ltd. All rights reserved.
Image Super-Resolution(SR)research has achieved great success with powerful neural *** deeper networks with more parameters improve the restoration quality but add the computation complexity,which means more inference...
详细信息
Image Super-Resolution(SR)research has achieved great success with powerful neural *** deeper networks with more parameters improve the restoration quality but add the computation complexity,which means more inference time would be cost,hindering image SR from practical *** the spatial distribution of the objects or things in images,a twostage local objects SR system is proposed,which consists of two modules,the object detection module and the SR ***,You Only Look Once(YOLO),which is efficient in generic object detection tasks,is selected to detect the input images for obtaining objects of interest,then put them into the SR module and output corresponding High-Resolution(HR)*** computational power consumption of image SR is optimized by reducing the resolution of input *** addition,we establish a dataset,TrafficSign500,for our ***,the performance of the proposed system is evaluated under several State-Of-The-Art(SOTA)YOLOv5 and SISR *** show that our system can achieve a tremendous computation improvement in image SR.
A direction of arrival (DOA) estimation method based on the spectral Capon rooting algorithm is developed. The developed method realises DOA estimation by real polynomial rooting technique rather than a grid search. I...
详细信息
A direction of arrival (DOA) estimation method based on the spectral Capon rooting algorithm is developed. The developed method realises DOA estimation by real polynomial rooting technique rather than a grid search. It provides a lower computation complexity and a better performance compared to the spectral Capon searching algorithm. Simulation results demonstrate the effectiveness of the method.
A new step-by-step decoding algorithm for decoding Reed-Solomon codes over GF(2(m)) is presented. Based on several properties of the syndrome matrices, the new step-by-step decoding algorithm can directly determine wh...
详细信息
A new step-by-step decoding algorithm for decoding Reed-Solomon codes over GF(2(m)) is presented. Based on several properties of the syndrome matrices, the new step-by-step decoding algorithm can directly determine whether every received symbol is an error locator, The detection of error location is based only on the determinant of a v x v syndrome matrix, where v is the number of errors. When an error location is found, its corresponding error value can also be determined by performing a determinant division operation between two syndrome matrices. The new decoding algorithm can significantly reduce computation complexity and improve the decoding speed compared with the conventional step-by-step decoding algorithm.
An enhanced covariances sparse representation method for direction-of-arrival (DOA) estimation is proposed. The method can estimate coherent sources with low computation complexity. The cross-Kronecker product terms o...
详细信息
An enhanced covariances sparse representation method for direction-of-arrival (DOA) estimation is proposed. The method can estimate coherent sources with low computation complexity. The cross-Kronecker product terms of the steering vector are introduced as an extra basis to improve the sparse model. Based on the enhanced model and iteration operation, the proposed method has greater precision in multiple coherent sources situations. Compared with several existing DOA estimation methods, simulation experiments have validated the effectiveness of the proposed method.
After passing a systematic bit through a turbo encoder, the encoding process will introduce some extent of correlation between a systematic bit and its associated parity bits. However, this correlation is neglected in...
详细信息
After passing a systematic bit through a turbo encoder, the encoding process will introduce some extent of correlation between a systematic bit and its associated parity bits. However, this correlation is neglected in the subsequent turbo decoding process so as to reduce its computational complexity. In this paper, we try to explore the feasibility of modeling the bit-level stochastic correlation for the iterative turbo decoding. By properly adjusting the parameter of the correlation model, we can approximate various degrees of the underlying correlation within the received codewords. Reduction in bit error rate (BER) then may benefit from a more accurate capture of the correlation information at the cost of requiring only a small additional computation complexity. Experimental results indicate that incorporating the correlation model into the turbo decoding process can achieve better BER performance than that of conventional turbo decoders over AWGN channels. (C) 2006 Elsevier B.V. All rights reserved.
The imaging performance and efficiency are two important issues for the multireceiver synthetic aperture sonar (SAS). Back projection (BP) algorithm is characterised by the high performance and low efficiency. In this...
详细信息
The imaging performance and efficiency are two important issues for the multireceiver synthetic aperture sonar (SAS). Back projection (BP) algorithm is characterised by the high performance and low efficiency. In this study, the authors first recall the standard BP algorithm based on the interpolation for the multireceiver SAS. Then, two improved BP algorithms based on the range Fourier transformation (FT) are presented. Considering the fact that the time delay in the time domain can be carried out by the phase shifting in the frequency domain, an FT shifting based BP algorithm avoiding the interpolation error is presented. Although this method produces the focusing result with high performance, it is very time consuming. In order to improve the imaging efficiency without loss of imaging performance, the authors propose an oversampling-based BP algorithm, which is based on the fact that the zero-padding in the frequency domain is equivalent to the interpolation in the time domain. After that, the computation complexity of three BP algorithms is analysed in detail. Finally, simulations and real data are exploited to validate the presented methods.
Here, we propose the use of the majorization-based indicator for quantum computation complexity introduced in Vallejos et al. (Phys. Rev. A 104:012602, 2021) as a tool to benchmark the complexity within reach of quant...
详细信息
Here, we propose the use of the majorization-based indicator for quantum computation complexity introduced in Vallejos et al. (Phys. Rev. A 104:012602, 2021) as a tool to benchmark the complexity within reach of quantum processors, when taking into account hardware and noise constraints. By considering specific qubit systems and native gate sets of currently available technologies, we numerically simulate the operation of various quantum processors in the presence of typical types of noise. We characterize their complexity for different native gate sets, qubit connectivity, and increasing number of gates. We identify and assess quantum complexity by comparing the performance of each device against benchmark lines provided by randomized Clifford circuits and Haar-random pure states. In this way, we are able to specify, for each specific processor, the number of native quantum gates which are necessary, on average, for achieving those levels of complexity. Moving toward real implementations, our results validate the use of the majorization-based indicator in the presence of noise. We determine how much noise one quantum processor can admit while maintaining high levels of complexity. Our benchmarking procedure can thus be used to set target levels for noise in quantum processors, while taking into account their physical constraints.
暂无评论