Advanced Materials Research Vol. 981

Abstract: The wavelength of Fiber Bragg grating (FBG) sensor signal demodulation simulation system based on the quasi-linear relationship between the transmission side band of optical filters and wavelength was established by the simulation software of MABTLAB. The simple system only consists of broadband source, sideband optical filters, couplers, a FBG, data acquisition and processing system. The relationship between the information of FBG central wavelength and the transmitted light intensity of sideband filter were obtained when the alternating and gradually varying signal applied to the FBG sensors, respectively. The FBG wavelength demodulation can be achieved by sideband filtering, and results are consistent with the theory.

Abstract: Continuous phase modulation (CPM) signal has the advantages of high bandwidth efficiency, continuous phase, faster decay speed of power spectrum, constant envelope and so on, which is widely used in communication systems. The degree of the phase smoothing is one of main factors that affect the decay speed of CPM signal power spectrum. One method of smoothing CPM signal phase based on different power sine function as the frequency modulation function is proposed. We draw the phase trajectory of baseband signal and the normalized power spectrum by using the MATLAB software. The spectrum characteristics of the signal generated have great improvement compared with MSK signal, which reach the desired goal.

Abstract: Particle filter is the most successful nonlinear filter for nonlinear filtering. However its resampling process has the critical problem existing is the particle impoverishment problem. In this letter, we propose a new corrected differential evolution particle filter for solving this problem. In this algorithm, the particles sampling from the importance distribution are regarded as the initial population of the Corrected Differential Evolution (CDE) algorithm, and the corresponding weights as the fitness functions. The optimal particles are obtained by the process of the CDE algorithm. Experiment results indicate that the proposed method relieves the particle degeneracy and impoverishment and improves the estimation precision.

Abstract: —In this paper, we propose a new way to implement the FFT Algorithm, which based on FPGA. At first we introduce the theory of FFT algorithm and its applications. Then the features of FFT IP core based on Altera FPGA is discussed. We elaborate the usage method of the customizable Altera FFT MegaCore function. A logic state machine is designed to create some command signals of this FFT IP core. Finally we use simulation tools Signal-Tap in quartus II inviroment to simulate and debug our FFT control module’s function. The result shows that this new control method of FFT IP core is feasible.

Abstract: Network on Chip(NoC)，a new proposed solution to solve global communication problem in complex System on Chip (SoC) design，has absorbed more and more researchers to do research in this area. Due to some distinct characteristics, NoC is different from both traditional off-chip network and traditional on-chip bus，and is facing with the huge design challenge. NoC router design is one of the most important issues in NoC system. The paper present a high-performance, low-latency two-stage pipelined router architecture suitable for NoC designs and providing a solution to irregular 2Dmesh topology for NoC. The key features of the proposed Mix Router are its suitability for 2Dmesh NoC topology and its capability of suorting both full-adaptive routing and deterministic routing algorithm.

Abstract: In the long baseline positioning system, underwater vehicle use transponder reply signals for positioning and navigation, reply signals aliasing is the main reason of inaccurate detection and instability detection. This paper aimed at the problem and research on signal aliasing in long baseline positioning system, theoretical and simulation results show that: Both overlap degree and overlap energy have a certain distribution. The size of signal aliasing area associated with signal overlap degree. The number of signal aliasing is different in different aliasing area. Signal aliasing will affect signal detection, and reduce the long baseline positioning accuracy.

Abstract: Orthogonal Frequency Division Multiplexing is considered as the key technology of the fourth generation of mobile communication technology. In this paper, an idea is proposed which solves the issue of multiuser resource allocation for OFDM based on swarm intelligence theory, and terminal bandwidth limitation is set as constraints addition as well. Theoretically, swarm intelligence algorithm could allocate resources more efficient and simulation results show that the proposed method is able to achieve better performance and higher system data rate than other similar algorithms under the same condition.

Abstract: In wireless communication, inter symbol interference (ISI) and signal distortion are often caused by the frequency deviation and time offset of wireless channel. To eliminate or reduce ISI, people proposed the channel equalization technology. However, traditional decision feedback equalization algorithm based on MMSE criterion equalizer (DFE-MMSE) often introduces the error diffusion which degrades the performance of the equalizer in iterative system. In this paper, we propose an improved DFE-MMSE algorithm to reduce the error diffusion and improve the performance of iterative equalization, with a correction factor. Simulation results show that our algorithm achieves better bit error rate, which makes it competent in more practical cases.

Abstract: In order to maximize low power-line channel capacity within the limited transmission bandwidth, a new transmitting power allocation algorithm based on the quality of service (QoS) strategy is proposed in this paper.Orthogonal frequency-division multiplexing (OFDM) is considered to support remarkable capacity of power-line channel. In order to derive the closed form expression of the maximum channel capacity in an OFDM power communication system, the relationship between channel capacity, signal to noise ratio (SNR) and modulation scheme is analyzed.Furthermore, some influence factors of power-line channel capacity, such as branches number, branches length and end-load impendence are analyzed in this paper. Simulation result shows that the mainly factors that affect the channel capacity of low power-line are branch number and load impendence; the performance of proposed algorithm is superior to the existed water-filling algorithms at the same SNR.

Abstract: Conventional DFT-based channel estimations suppress the noise by a cut-off filter in time domain. However, the potentially suffer significant performance loss due to the energy leakage. In this paper, based on the detailed analysis of the channel impulse response (CIR) leakage in the LTE-A uplink system, a novel discrete Fourier transform (DFT)-based channel estimation algorithm is proposed. This algorithm estimates the average noise power in frequency domain to get a noise threshold, which is then used in time domain to eliminate the noise by DFT and reduce the spectrum leakage. The simulation results show that the proposed algorithm can effectively improve the BER performance, and has a moderate complexity compared to existing DFT based algorithms.