Shaojing Su

Information-Dispersion-Entropy-Based Blind Recognition of Binary BCH Codes in Soft Decision Situations

A method of blind recognition of the coding parameters for binary Bose-Chaudhuri-Hocquenghem (BCH) codes is proposed in this paper. We consider an intelligent communication receiver which can blindly recognize the coding parameters of the received data stream. The only knowledge is that the stream is encoded using binary BCH codes, while the coding parameters are unknown. The problem can be addressed on the context of the non-cooperative communications or adaptive coding and modulations (ACM) for cognitive radio networks. The recognition processing includes two major procedures: code length estimation and generator polynomial reconstruction. A hard decision method has been proposed in a previous literature. In this paper we propose the recognition approach in soft decision situations with Binary-Phase-Shift-Key modulations and Additive-White-Gaussian-Noise (AWGN) channels. The code length is estimated by maximizing the root information dispersion entropy function. And then we search for the code roots to reconstruct the primitive and generator polynomials. By utilizing the soft output of the channel, the recognition performance is improved and the simulations show the efficiency of the proposed algorithm.

Blind identification of convolutional encoder parameters.

This paper gives a solution to the blind parameter identification of a convolutional encoder. The problem can be addressed in the context of the noncooperative communications or adaptive coding and modulations (ACM) for cognitive radio networks. We consider an intelligent communication receiver which can blindly recognize the coding parameters of the received data stream. The only knowledge is that the stream is encoded using binary convolutional codes, while the coding parameters are unknown. Some previous literatures have significant contributions for the recognition of convolutional encoder parameters in hard-decision situations. However, soft-decision systems are applied more and more as the improvement of signal processing techniques. In this paper we propose a method to utilize the soft information to improve the recognition performances in soft-decision communication systems. Besides, we propose a new recognition method based on correlation attack to meet low signal-to-noise ratio situations. Finally we give the simulation results to show the efficiency of the proposed methods.

High-Speed Packet Classification with Efficient Parallel Range Match for IP Network Applications

Packet classification has been critical data path function for supporting quality of service (QoS), resource reservation protocol (RSVP) and broad range of multimedia services. Hardware based solution is necessary to keep up with high-speed rate up to OC192 processing. However, the range match in multi-fields classification is still one of the bottleneck problems. In this paper, a novel structure called range match block is designed. The range match block stores range rules directly and performs range match parallel in each entry at high-speed. Experimental results show the range match block can process about 66.7 million packets per second (Mpps). Furthermore, we propose a multi-field packet classification architecture based on range match block and ternary CAM. The architecture is well-suited for all kinds of network applications.

Blind Demodulation of Chaotic Direct Sequence Spread Spectrum Signals Based on Particle Filters

Applying the particle filter (PF) technique, this paper proposes a PF-based algorithm to blindly demodulate the chaotic direct sequence spread spectrum (CDS-SS) signals under the colored or non-Gaussian noises condition. To implement this algorithm, the PFs are modified by (i) the colored or non-Gaussian noises are formulated by autoregressive moving average (ARMA) models, and then the parameters that model the noises are included in the state vector; (ii) the range-differentiating factor is imported into the intruder’s chaotic system equation. Since the range-differentiating factor is able to make the inevitable chaos fitting error advantageous based on the chaos fitting method, thus the CDS-SS signals can be demodulated according to the range of the estimated message. Simulations show that the proposed PF-based algorithm can obtain a good bit-error rate performance when extracting the original binary message from the CDS-SS signals without any knowledge of the transmitter’s chaotic map, or initial value, even when colored or non-Gaussian noises exist.

Using Multidimensional ADTPE and SVM for Optical Modulation Real-Time Recognition

Based on the feature extraction of multidimensional asynchronous delay-tap plot entropy (ADTPE) and multiclass classification of support vector machine (SVM), we propose a method for recognition of multiple optical modulation formats and various data rates. We firstly present the algorithm of multidimensional ADTPE, which is extracted from asynchronous delay sampling pairs of modulated optical signal. Then, a multiclass SVM is utilized for fast and accurate classification of several widely-used optical modulation formats. In addition, a simple real-time recognition scheme is designed to reduce the computation time. Compared to the existing method based on asynchronous delay-tap plot (ADTP), the theoretical analysis and simulation results show that our recognition method can effectively enhance the tolerance of transmission impairments, obtaining relatively high accuracy. Finally, it is further demonstrated that the proposed method can be integrated in an optical transport network (OTN) with flexible expansion. Through simply adding the corresponding sub-SVM module in the digital signal processer (DSP), arbitrary new modulation formats can be recognized with high recognition accuracy in a short response time.

Breaking Chaotic Direct Sequence Spreading Spectrum Signals Under the Multipath Fading Channel

In order to break chaotic direct sequence spreading spectrum (CD3S) signals under the multipath fading channel, a particle filter based algorithm combining blind channel equalization with chaos fitting is proposed. To implement this algorithm, the intruder substitutes a different chaotic equation into the state-space equations of the channel and the chaos fitting, and then multiple particle filters are used for blind channel equalization and chaos fitting simultaneously by implementing them in reciprocal interaction. As a result, the impact brought about by the multipath fading channel and additive noises can be overcome. Furthermore, the range-differentiating factor is used to make the inevitable chaos fitting error advantageous based on the chaos fitting method. Thus, the CD3S signals can be broken according to the range of the estimated message. Simulations show that the binary message signal can be extracted from the CD3S signals without any knowledge of the chaotic transmitter’s structure, parameters, initial value, or the channel characteristics.

Software solutions to quality enhancement of moire fringes in displacement measuring

To acquire high precision of subdivision in optical displacement measuring, the signal quality of moire fringes must be kept reliable and constant. Several software solutions to enhance the signal quality of moire fringes are provided in this paper. The process platform is based on SHARC DSP and flash sample technique. Three methods of adaptive digital filter are used respectively to eliminate the unwanted drift of signal, improve the orthogonality of two channels of sine and cosine intensity signals of moire fringe, and keep the amplitude of the signal constant. Firstly, the operation procedure of the acquisition and process system is described, then the principle of the adaptive signal process is explained. And at the same time, the result of the experiment is also listed to show the effects of the process software in digital signal processor.

Distributed remote-control protocol: DRCP for field bus

This paper introduces the master-slave DRCP (Distributed Control Protocol), a new protocol for field bus. In this protocol, the master controller uses differential signals to transmit control command and to communicate with the executive units. It can control several executive units at the same time, and can also command each unit respectively. Because the protocol adopts bi-directional communication mode, the controller can obtain the feedback information and measure data from the executive units while it is sending commands. So the protocol has data acquisition ability. First, the reason and significance to bring forward this protocol is presented, then the physical link and the signals transmitted on data line is introduced, which is followed with an example based on RS485 standard. Secondly, the application situation and system configuration to utilize this protocol is described. In this part, the standard to select the operation speed of processor is given. Thirdly, the paper emphasizes on communication regulation. In the end, an applied example is given.

Optimization simulation of aeromagnetic detection based on COMSOL multiphysics

For the high cost of practicality experiments and the low precision of available model data cause the deficiently of the effectiveness of the aeromagnetic detection result, a magnetic field simulation method of submarine aircraft model is proposed based on COMSOL Multiphysics finite element software. First, the submarine is equivalent to the hollow cylinder model, and the magnetic field distribution of the distance of 5 times the length of the submarine is received through the simulation. Then the aircraft geometrical model is established to analyze the mechanism of aircraft jamming magnetic field, and the four-way flight scheme of compensation flight state is proposed to get magnetic field simulation data. For the simulation difficulties of large-scale model in the detection flight state, a simulation method of model separation and data superposition is proposed to get the component and the total data of magnetic field. Finally, the aircraft interference magnetic field modeling and the use of ridge estimation method to compensate for compensation flight and detection flight magnetic field data. Four-course flight data compensation accuracy within 0.5nT and detection flight data after compensation can be distinguished the submarine signal. The correctness of the finite element simulation method and the magnetic field data is verified, which is of great significance to the study of aeromagnetic deection simulation.

Chromatic Dispersion Estimation for Optical PDM-QPSK Communication System without Symbol Rate Limitation

Chromatic dispersion (CD) is one of main channel impairments in the ultra-long optical fiber communication based on polarization-division-multiplexing (PDM) technic. Therefore, CD estimation is an important step during coherent detection in the optical receiver. In this paper, an accurate and fast CD estimation method using two mathematical autocorrelation features of received signal is presented. We firstly use the autocorrelation of signal power waveform (ACSPW) to roughly estimate CD value and scanning range, and then singular value of signal autocorrelation matrix (SVSACM) is utilized to search the maximum value in the estimated CD range for accurate CD estimation. Compared with simply used ACSPW in the PDM-quadrature phase shift keying (QPSK) transmission system, the results of numerical simulations show that the proposed method can effectively expand the symbol rates limitation. Moreover, the scanning efficiency of SVACM can be improved to be faster than that without coarse estimation, due to the fact that the CD scanning size becomes relatively small