Kaiyu Qin

Modulated wideband converter with run length limited sequences

The modulated wideband converter (MWC) is a powerful subNyquist sampling system, which can acquire sparse wideband analog signal without prior information of frequency support. In this letter, we aim at enlarging the input bandwidth of MWC under a certain chip rate constraint, which is realized by utilizing run length limited (RLL) sequence in the modulation stage. Simulation results show that when applying our method, input bandwidth of MWC can be improved by 25% without reconstruction performance loss.

High-Precision, Permanently Stable, Modulated Hopping Discrete Fourier Transform

A new modulated hopping Discrete Fourier Transform (mHDFT) algorithm which is characterized by its merits of high accuracy and constant stability is presented. The proposed algorithm, which is based on the circular frequency shift property of DFT, directly moves the k-th DFT bin to the position of k = 0, and computes the DFT by incorporating the successive DFT outputs with arbitrary time hop L. Compared to previous works, since the pole of mHDFT precisely settles on the unit circle in the Z-plane, the accumulated errors and potential instabilities, which are caused by the quantization of the twiddle factor, are always eliminated without increasing much computational effort. The numerical simulation results verify the effectiveness and superiority of the proposed algorithm.

Dual-Mode Blind Equalization Algorithm for High-Order QAM

A novel dual-mode blind equalization algorithm for high-order Quadrature Amplitude Modulation (QAM) is presented. The proposed algorithm consists of the generalized mult-mudulus algorithm (GMMA) for initial convergence during blind startup, and the decision–directed least mean square algorithm (DDLMS) which is used to enhance the performance. The two operation modes are automatic switched according to the equalizer output error level. Combined with step-size parameter variation online in each mode, the blind equalization solution can converge rapidly with low residual tap fluctuation noise. The simulation results show that the proposed techniques converge quickly and reduce the intersymbol interference (ISI) caused by the propagation channel to -43dB, with about 10dB improvement contrast to the GMMA. On the other hand, the phase rotation introduced by channel is corrected simultaneously.

Frequency pre-estimation aided carrier recovery algorithm for high-speed M-PSK communication

A novel non-data-aided carrier recovery algorithm combined with large frequency offset pre-estimation for high-speed M-PSK communication is presented, which can counteract the large carrier frequency offsets at fast speed and have less phase-jitter in phase locked state. The proposed two-step solution consists of a novel frequency offset pre-estimator to specify carrier frequency location blindly and acquire coarse large carrier frequency offset rapidly. A decision-directed carrier recovery loop with variable loop bandwidth is used for fine phase tracking. Compared to previous works, a remarkable improvement is achieved in terms of acquisition speed, while keeping a very low residual phase jitter. Because of those considerable merits, the scheme is quite suitable for designing high performance communication system.

Arbitrary Block-Sparse Signal Reconstruction Based on Incomplete Single Measurement Vector

Within the compressive sensing framework, reconstruction algorithms of block-sparse signal (BSS) often have special requirements on sparsity patterns. As a result, only some particular BSSs can be reconstructed. In this paper, we present a new universal greedy iteration algorithm, named block-matching pursuit (BMP), for BSS with an arbitrary sparsity pattern. The BMP can reconstruct the target signal without prior information of the signal’s sparsity pattern and achieves an outstanding reconstruction probability. In each iteration, the BMP first estimates a part of support set of the signal by a correlation test. Based on the estimated support and the property of nonzero blocks, coordinates of all possible nonzero entries can be obtained to form a candidate list. Then some coordinates in the list, which are deemed sufficiently reliable by a final test, are added to the current estimated support set. When iteration ends, the true sparsity level, namely true support set, can be exactly calculated by searching a support set with the smallest cardinality; once the true set is derived, the target signal can be reconstructed. Theoretical analysis indicates that BMP can reconstruct the target signal as long as the sampling matrix meets a certain condition. Simulation results show that the reconstruction performance of BMP is better than that of other greedy algorithms. In particular, if the signal with high sparsity level contains a few blocks, BMP can still reconstruct it with a high probability.

Parameter Estimation Algorithm for the Exponential Signal by the Enhanced DFT Approach

Abstract Based on enhanced interpolation DFT, a novel parameter estimation algorithm for the exponential signal is presented. The proposed two-step solution consists of a preprocessing unit which constructs a new signal sequence by continuously cycle shifting sample points and summing up N buffered exponential signal sample sequences, then an interpolation DFT engine to obtain accurate parameter estimation of the exponential signal based on the signal sequence generated by the preprocessing unit. Compared to previous works, owing to the combination of the pretreatment and the interpolation DFT analysis, the tedious iteration for spectral leakage elimination can be removed, and remarkable improvements are achieved in terms of estimation accuracy and speed. The simulation results verify the effectiveness of the proposed algorithm.

Fractional order Liu-system synchronization and its application in multimedia security

This paper proposed a method to achieve the projective synchronization of fractional order Liu-system. Based on constructing an approximation integer order system for the fractional order Liu-system, a control algorithm is proposed to improve on the projective synchronization in the new integer order systems. The synchronization method is adopted to realize the generalized synchronization of 2.7 order Liu-system, and the simulation result verify the effectiveness. This control scheme can be used in some multimedia security and information transmission based on Internet.

Dual-mode blind decision feedback equalizer for high-order QAM multi-domain measurement

Based on real-time multi-domain signal analysis architecture for high-order Quadrature Amplitude Modulation (QAM) communication, a dual-mode blind adaptive decision feedback equalization (DFE) scheme for high-order QAM real-time multi-domain analysis and specifications measurement is presented. The proposed two-phase scheme consists of the generalized multi-modulus algorithm (GMMA) for initial convergence during blind startup, and the decision-directed least mean square algorithm (DDLMS) which is used to enhance the performance. The two operation modes are automatic switched according to the equalizer output error level. Combined with step-size parameter variation online in each mode, the blind equalization solution can converge rapidly with low residual tap fluctuation noise. The simulation results show that the proposed techniques converge quickly and reduce the residue mean squared error (MSE) caused by the propagation channel to −40dB. On the other hand, the proposed algorithm is practically implemented in the communication testing system. The measurement error of EVM is less than 2% for 6.4MSps 256QAM in the 20MHz real-time analysis bandwidth. For these considerable merits, the scheme is quite suitable for high-resolution communication measurement instruments design.

Synchronization in coupled fractional order Chen-system and its application in secure communication

A new projective synchronization in coupled fractional order chaotic Chen systems is studied. First, an approximation integer order system for the fractional order Chen system is constructed. Then, since the scaling factor of PS (projective synchronization) is predicted hardly, a control algorithm is thus proposed to improve on the projective synchronization in the new integer order systems. This control scheme can be used in some secure communication systems. Illustrations are also given to show the rightness of the theoretical analysis and the effectiveness of the method proposed.

Adaptive blind equalization algorithm with multi-module for high-order QAM real-time multi-domain measurement: Adaptive blind equalization algorithm with multi-module for high-order QAM real-time multi-domain measurement

A hybrid loop filter includes an integrator having an input and an output wherein the output forms an output of the hybrid loop filter, a plurality of transconductance amplifiers having an input and an output wherein each output of the plurality of transconductance amplifiers is coupled to the input of the integrator, a switched capacitor low pass chain having an input and a plurality of branches wherein each of the plurality of branches is coupled to the input of a separate one of said plurality of transconductance amplifiers, and a feedthrough branch having an input and an output wherein the input is coupled to the input of the switched capacitor low pass chain to form an input of said hybrid loop filter, and the output is coupled to the input of a separate one of the plurality of transconductance amplifiers.