Compressive sensing based channel estimation for NC-OFDM systems in cognitive radio context by Xue-yun HE, Rong-fang SONG, Ke-qin ZHOU

“…A new channel estimation based on compressive sensing(CS)in non-contiguous orthogonal frequency division multiplexing(NC-OFDM)system was proposed.As for NC-OFDM systems in cognitive radio context,the infrastructure of CS-based channel estimation,the design of pilot patterns and the algorithm of channel estimation were explored.Especially,a criterion of optimizing pilot pattern in the CS-based channel estimation was proposed by minimizing the mutual coherence of the measurement matrix in CS theory.Simulations show that,under many patterns of deactivated subcarriers,CS-based channel estimation obtains much better performance than existing NC-OFDM channel estimation methods in terms of the mean square error of the channel estimate as well as the bit error rate of the system.…”
Get full text

Bandwidth extension method based on nonlinear audio characteristics classification by Li-yan ZHANG, Chang-chun BAO, Xin LIU, Xing-tao ZHANG

“…A bandwidth extension method based on audio classification was proposed.Time series of audio signals were classified into four types based on recurrence plot and recurrence quantification analysis,and the fine spectrums were recovered by taking advantage of four methods respectively.In addition,the spectrum envelope and energy gain were adjusted by Gaussian mixture model and codebook mapping on the basis of soft decision respectively.Subjective and objective testing results indicate that the proposed method has good quality compared with conventional blind bandwidth extension methods,and the performance of ITU-T G.722.1 codec with the proposed algorithm is better than that of G.722.1C codec at the same bit rate.…”
Get full text

An Iteration-Time Combination Method to Reduce the Dynamic Degradation of Digital Chaotic Maps by Yao Wu, Lingfeng Liu

“…A type of pseudorandom bit generator based on the iteration-time combination method is proposed to demonstrate its simple application.…”
Get full text

Robust reconstruction of Wyner-Ziv frame for no-feedback distributed video coding by Hao QIN, Xue-lu PENG, Bin SONG, Hai-hua LIU

“…In no-feedback distributed video coding,a robust reconstruction algorithm for Wyner-Ziv frame was proposed.To avoid the video quality degradation caused by the bit plane decoding errors,DC coefficients and AC coefficients were reconstructed with different methods.In particular,for each failure decoded quantized DC coefficient,with the help of the correlation information from the encoder,the algorithm was able to adaptively adjust the contribution of the quantized side information and the decoded quantized DC coefficient to the reconstruction.Simulation results show that compared with the MMSE (minimum mean square error) algorithm,the proposed method can increase the average PSNR (peak signal-to-noise ratio) of reconstructed video greatly,and also yield significant improvement of the subjective video quality.…”
Get full text

Performance analysis of Bluetooth packet transmission and adaptive packet selection strategy by YANG Fan, WANG Ke, QIAN Zhi-hong

“…Relations between bit error rate and average received signal-to-noise ratio （SNR） in AWGN channel were derived for three modulation modes defined by Bluetooth 2.0+EDR new specification. …”
Get full text

Ambient backscatter communications technology for batteryless IoT by Qin TAO, Caijun ZHONG, Zhaoyang ZHANG

“…As one of the core enabling technologies supporting the batteryless Internet of things(IoT),ambient backscattering communication technology has the characteristics of low power consumption and low cost.Firstly,the basic concept of ambient backscattering communication technology and the research status at home and abroad were introduced.Then,based on an in-depth analysis of the differences between ambient backscattering communication technology and RFID technology,the technical difficulties faced by the ambient backscattering communication system were described in detail,including large detection delay,high bit error rate,low transmission rate and short communication distance.In addition,a series of potential solutions to the challenges were proposed.Finally,the future research directions of ambient backscattering communication were prospected.…”
Get full text

Multiplierless discrete Fourier transform based on moments by LIU Zhen-bing, LIU Jian-guo, WANG Guo-you

“…A novel algorithm to perform Discrete Fourier Transform（DFT） multiplierlessly was proposed.First, by modular mapping and truncating Taylor series expansion, the DFT was expressed in the form of the product of the constants and discrete moments.Second, by performing appropriate bit operations and shift operations in binary system, the product could be transformed to some additions of integers.The proposed algorithm only involved integer additions and shifts because the discrete moments could be computed only by integer additions.The systolic VLSI was designed to perform the new algorithm, followed by complexity analysis.Compared with the state-of-the-art systolic structure, the proposed design was multiplierless and easier to implement with less hardware and time.The approach was also applicable to other discrete transforms.…”
Get full text

Research on satellite-ground adaptive modulation and coding techniques based on intellgent prediclion of channel state by JI Shuo, SUN Yaohua, PENG Mugen

“…Simulation validation has demonstrated that adaptive modulation and coding based on channel prediction can improve the bit error performance of the link to a certain extent.…”
Get full text

Sparse expression and sensing of fast fading channel for OFDM systems with imperfect carrier synchronization by Yong FANG, Wei-jie ZHAO, Min WANG

“…A sparse expression of fast fading channel and its sensing method were proposed for orthogonal frequency-division multiplexing (OFDM) system of sparse pilot under the condition of imperfect carrier synchronization.First,a sparsified core vector based sparse expression of the generalized channel impulse response (G-CIR) was proposed by deriving compressed sensing model of the sparse pilot system.Then,both the sparsified core vector and G-CIR were reconstructed by orthogonal matching pursuit(OMP).Simulation results demonstrate that the proposed algorithm can effectively reduce the bit error rate (BER) of the OFDM system with imper ect carrier synchronization.…”
Get full text

Construction method and performance analysis of chaotic frequency-hopping sequences based on Logistic-Sine-Cosine mapping by CAO Chunjie, WANG Yinglin, SUN Yang, TAO Hongfei, YANG Haoning, SHI Jingcheng, DAI Junhao, SUN Jingzhang

“…Then, the intermediate multi-bit extraction method was used to quantify the sequence generated by the mapping as a frequency-hopping sequence. …”
Get full text

Frame erasure concealment method used for wideband embedded speech codec by ZHU Heng, BAO Chang-chun, LI Rui

“…An efficient frame erasure concealment（FEC）method for wideband embedded speech codec was proposed.The erased speech frame was classified as voiced,unvoiced,silence,unvoiced transit to voiced and voiced transit to unvoiced at decoder.The energy of excitations was carefully controlled based on the classification of the speech.To match with the configuration of the embedded speech codec,the adaptive codebook for erased frame was recovered with the last frame’s bit-stream.For increasing the robustness of the codec,the contribution of adaptive codebook was prop-erly constrained at encoder.The proposed FEC method is very simple and has a good performance without extra delay and bits requirements in codec.This method has been applied to an embedded variable bits rate codec submitted to ITU-T as a candidate.…”
Get full text

Research and implement of embedded wireless mobile communication system by TONG Xiao-nian1, AN Xing-ya2, LAN Xiao-pang3, WANG Jiang-qing1

“…In order to reduce hardware cost of embedded wireless mobile communication system and improve developing efficiency of embedded network protocol, the embedded wireless mobile communication terminal based on 8-bit basic MCU was proposed. Furthermore, according to software engineering principle, the general frame was designed to gener- ate embedded network protocol by UML state machine technology. …”
Get full text

An audio steganography algorithm based on segment-STC by Xueyuan ZHANG, Rangding WANG, Diqun YAN, Yuzhen LIN

“…Firstly, the LSB-stream (least significant bit, LSB) of audio cover was segmented as few sub-segments. …”
Get full text

Image Encryption Performance Evaluation Based on Poker Test by Shanshan Li, Weiyang Sun

“…The cipher text image is transformed to bit stream. Then, Poker Test is implemented. The proposed metric considers the neighbor correlations of image by neighborhood selection and clip scan. …”
Get full text

Study of performance of UWB transmitted-reference receivers by YANG Gang1, KANG Jie2, SHI Ren1

“…The principle and advantage were analyzed about UWB transmitted-reference （TR） receiver.Moreover,considering many UWB communications had little channel variance in the course of transmitting a few bits data,an improved TR receiver was presented by extending TR signal set to the sum of several reference signals and many data signals.The performance of this improved TR receiver and basic TR receiver were detailed analyzed in theory and simulated in the IEEE UWB multipath channel models CM1 and CM2.The results show that bit error rate and data transmission efficiency of this improved TR receiver are better than basic TR receiver,at the cost of a little rise of structure complexity.…”
Get full text

Method for assisted-GPS positioning based on ambiguity resolution in weak signal environment by SONG Cheng, WANG Fei-xue, ZHUANG Zhao-wen

“…An assisted-GPS positioning algorithm was proposed.Based on this algorithm, the receiver needn’t accomplish the bit synchronization, frame synchronization and navigation data demodulation, which were usually necessary for the conventional GPS receiver, it could implement the positioning solution only by the measurement of pseudo-code phase and the assistance data（including ephemeris information and satellite clock corrections etc.）.Compared with the conventional GPS positioning algorithm, the proposed algorithm increases the ambiguity of the signal transmission time as an unknown parameter for the pseudorange equation.When the initial errors of approximate location and receiver’s clock bias were subjected to a constraint domain, the ambiguity of the signal transmission time could be eliminated.Then, the iteratively equation for this algorithm was derived, and the main steps were summarized.The simulation results show the validity of the algorithm.…”
Get full text

History and trajectory of Rossetti's works ‘after Dante’: between private collections and museums by Yannick Le Pape

“…Dante was definitely popular in Great-Britain, so that it was quite easy for Rossetti to negotiate his works, and no doubt that the emerging speculative collecting for businessmen did limit sales to a short panel of wealthy rivals who took advantage of museums' hesitations about Pre-Raphaelitism — as well as foreign critics focused on Rossetti a bit too late, when his works were already in the English acquisitions field. …”
Get full text

Research and development of degree distribution in the rateless code by Yue QIAO, Yusun FU, Muyun YUAN, Jinhui TANG

“…As a kind of deletion coding technology, the rateless code reduces feedback retransmission and has the characteristics of flexible bit rate and simple compilation code, which has broad application prospects in many fields.As the basis of rateless code design, degree distribution has a crucial impact on the performance of the rateless code With the wide application of the rateless code, the design of degree distribution also needs to change with changes in scenarios and needs.Firstly, the development and application of the rateless code were discussed.Starting with several classical rateless codes and degree distributions, the current research and development of the degree distribution were summarized and analyzed from three perspectives of application scenarios, optimization targets and existing optimization methods.Finally, the development and application trend of rateless codes and degree distribution were discussed.…”
Get full text

Exponential information’s extraction from power traces of modulo exponentiation implemented on FPGA by WU Zhen, CHEN Yun, CHEN Jun, WANG Min

“…A power analysis model on modulo exponentiation’s computation suitable for real environment was presented in the basis of analysis to the great amount of power traces in the rough.And a method of signal processing for extracting exponential information from the initial power traces was inferred too.Hereby,a power analysis platform was designed and implemented.The exponential information submerged in power traces of 32bit modulo exponentiation algorithms applied in a FPGA chip was successfully extracted where after.Meanwhile,a conclusion about SPA attack on RSA made by Messerges et al,such as the problem with an SPA attack was that the information about the secret key was difficult to directly observe,was proved to be incorrect.Finally,the static masking algorithm for modulo exponentiation of anti-SPA attack was also validated in this testing platform.…”
Get full text

Hybrid genetic algorithm based optimization of pilotpattern by Hanbing ZHENG, Xiang YU, Weiwei WANG

“…In OFDM system,sparse channel estimation based on compressed sensing(CS)can make full use of the inherent sparse degree of the wireless channel,which can reduce the pilot overhead and improve the spectrum efficiency.Therefore,a new method based on hybrid genetic algorithm was investigated for the pilot design of CS channel estimation,which was based on the minimization of the matrix cross correlation in the CS theory.In this method,genetic algorithm was used to obtain the initial sub-optimal pilot sequence,and then combined with the pilot position and pilot power,each entry of pilot pattern could be sequentially updated and optimized to make the minimum correlation of measurement matrix.Simulation results show that the proposed method can ensure a better mean square error and bit error rate compared to the pseudo-random pilot design and the equal distance pilot design.…”
Get full text