Channel estimation algorithms for cooperative spectrum sensing in amplify‐and‐forward cooperative system

In amplify‐and‐forward (AF)‐based cooperative spectrum sensing system, the bit‐error‐rate (BER) performance and detection probability will decrease because of the existence of channel estimation error. In this paper, the influence of channel estimation error on system performance is firstly deduced, and then, linear minimum mean‐square error (LMMSE) channel estimation algorithm with filtering delay time‐domain windowing (LMMSE‐filtering‐DTW) technique and modified singular value decomposition‐based LMMSE algorithm are proposed to improve the channel estimation performance for code division multiple access system and orthogonal frequency division multiplexing system in AF cooperative scenario, respectively. Simulation results verify the effectiveness of the two proposed channel estimation algorithms in cooperative spectrum sensing, and when E_b/ N₀ is bigger than 20 dB, given the required false alarm probability smaller than 15%, the difference of detection probability between the channel obtained using the proposed channel estimation algorithms and the ideal channel is less than 2.5%, respectively. Copyright © 2012 John Wiley & Sons, Ltd.     

Effective and Efficient Video Compression by the Deep Learning Techniques

Deep learning has reached many successes in Video Processing. Video has become a growing important part of our daily digital interactions. The advancement of better resolution content and the large volume offers serious challenges to the goal of receiving, distributing, compressing and revealing high-quality video content. In this paper we propose a novel Effective and Efficient video compression by the Deep Learning framework based on the flask, which creatively combines the Deep Learning Techniques on Convolutional Neural Networks (CNN) and Generative Adversarial Networks (GAN). The video compression method involves the layers are divided into different groups for data processing, using CNN to remove the duplicate frames, repeating the single image instead of the duplicate images by recognizing and detecting minute changes using GAN and recorded with Long Short-Term Memory (LSTM). Instead of the complete image, the small changes generated using GAN are substituted, which helps with frame-level compression. Pixel wise comparison is performed using K-nearest Neighbours (KNN) over the frame, clustered with K-means and Singular Value Decomposition (SVD) is applied for every frame in the video for all three colour channels [Red, Green, Blue] to decrease the dimension of the utility matrix [R, G, B] by extracting its latent factors. Video frames are packed with parameters with the aid of a codec and converted to video format and the results are compared with the original video. Repeated experiments on several videos with different sizes, duration, Frames per second (FPS), and quality results demonstrated a significant resampling rate. On normal, the outcome delivered had around a 10% deviation in quality and over half in size when contrasted, and the original video.     

基于EEMD-SVD-LTSA的高速列车蛇行演变特征提取框架

高速列车一旦出现蛇行失稳，列车的运行安全会受到严重威胁。在出现蛇行失稳前，高速列车会进入小幅蛇行发散状态，因此监测列车小幅蛇行演变趋势可以预测列车的运行状况，然而现有的文献鲜有对小幅蛇行演变特征进行研究，为此，提出一种基于EEMD-SVD-LTSA的高速列车特征提取框架，识别其演变趋势是小幅发散还是小幅收敛，进而预测列车运行状况。通过在线实验数据验证表明，提出的框架能成功提取高速列车小幅收敛、小幅发散的运行特征，且使用LSSVM的识别率达到100%，从而及时预测高速列车的运行状态，保障列车的运行安全。     

超分辨测向中奇异值分解的FPGA实现

奇异值分解是超分辨测向技术的核心组成部分,现有的并行实现方案适用范围窄,运算量大,迭代时间长.为了满足测向接收机系统的高实时性需求,结合双边Jacobi算法的交换策略和单边Jacobi算法的求角结构,提出了一种改进的实现方法.该实现方法修正了脉动阵列的收敛性问题,提高了复数矩阵的收敛速度.同时,给出了算法的现场可编程门阵列(FPGA)实现结构.仿真结果证明该方案耗时在百微秒以内,能够应用于电子侦察设备.