A NOVEL FRAMEWORK OF ONLINE NETWORK CODING FOR MULTICAST SWITCHES WITH CONSTRAINED BUFFERS

Network coding is able to address output conflicts when fanout splitting is allowed for multicast switching.Hence,it successfully achieves a larger rate region than non-coding approaches in crossbar sw...     

基于L∞最小搜索和陪集码的高光谱图像无损及近无损压缩

 分布式信源编码(DSC)由于其较低的编码复杂度及较高的抗误码性被应用于高光谱图像压缩.在典型的基于陪集码的分布式高光谱图像无损压缩算法s-DSC(scalar coset DSC)框架下,本文指出最优的预测准则应为无穷范数最小,提出了基于L_∞最小搜索的预测方法来逼近最优准则,并将框架推广到近无损压缩.实验表明,和原有的s-DSC相比,本文算法无损压缩的平均码率降低了大约0.25bpp,近无损性能也明显优于JPEG-LS,本文算法具有较低的计算复杂度、较高的压缩性能,且具有一定的抗误码能力,适用于星上压缩.     

非完全无线报文重传分析研究及其分治策略

网络编码为无线网络报文重传问题WPRTPs(Wireless Packet ReTransmission Problems)提供了有效解决途径.现有关于WPRTP问题的研究主要针对完全无线网络报文重传问题P-WPRTPs(Perfect WPRTPs),而尚未发现对非完全无线网络报文重传问题IP-WPRTPs（ImPe...     

OFDM系统中高峰均比的抑制技术分析

正交频分复用(OFDM)技术作为一种高速信息传输技术,具有频谱利用率高、抗频率选择性衰落和码间干扰能力强等优势,但由于OFDM信号是通过多载波调制后的合成信号,所以OFDM信号存在较高的峰均比,这会给传输系统带来许多不利因素,限制了OFDM技术的应用.文章针对OFDM系统中存在的高峰均比提出了一些相关的抑制技术,提高了...     

复数域网络编码中最大似然解码算法的改进

针对复数域网络编码中继网络,提出一种改进的中继处的最大似然解码算法。当传统的最大似然解码算法使用在复数域网络编码中继网络中时,计算复杂度会随着信息星座图映射方式的改变而大大增加。为了降低计算复杂度,在前人研究的基础上提出一种改进的最大似然解码算法,该算法利用无线中继网络通信系统的非对称性,在解码时,先进行预判决,然后进行精确判决,这样可以大大降低计算复杂度,提高了系统性能。     

无线视频传输的容错编码研究

基于无线视频监控传输技术进行无线信道视频图像传输的过程中,经常面临数据传输错误、带宽变化、网络拥塞导致的视频数据丢失问题,严重影响了图像质量。Joint Video Team(JVT)of ISO/IECMPEG and ITU-T VCEG提出了可伸缩视频编码(SVC),可实现视频空间、时间和图像质量的完全伸缩,本文结合率失真优化算法将可伸缩编码作为容错工具,引入了不同层数据,根据B-D代价函数决定自动重传机制,降低了视频数据丢失对图像质量的影响。仿真结果表明,该方法大大提高了视频码流的抗误码能力和传输的鲁棒性。     

A survey of efficient MDCT implementations in MP3 audio coding standard: Retrospective and state-of-the-art

This tutorial paper describes various efficient implementations (published and new unpublished) of the forward and backward modified discrete cosine transform (MDCT) in the MPEG layer III (MP3) audio coding standard developed in the time period 1990-2010, including the efficient implementation of polyphase filter banks for completeness. The efficient MDCT implementations are discussed in the context of (fast) complete analysis/synthesis MDCT filter banks in the MP3 encoder and decoder. In general, for each efficient forward/backward MDCT block transforms implementation are presented: complete formulas or sparse matrix factorizations of the algorithm, the corresponding signal flow graph for the short audio block and the total arithmetic complexity as well as the useful comments related to improving the arithmetic complexity and a possible structural simplification of the algorithm. Finally, all efficient forward/backward MDCT implementations are compared both in terms of the arithmetic complexity and structural simplicity. It is important to note that almost all presented algorithms can be also used for the 2ⁿ-length data blocks in others MPEG audio coding standards and proprietary audio compression algorithms.     

Design of new format for mass data compression

In the field of lossless compression,most kinds of traditional software have some shortages when they face the mass data.Their compressing abilities are limited by the data window size and the compressing format design.This paper presents a new design of compressing format named ’CZ format’ which supports the data window size up to 4 GB and has some advantages in the mass data compression.Using this format,a compressing shareware named ’ComZip’ is designed.The experiment results support that ComZip has better compression ratio than WinZip,Bzip2 and WinRAR in most cases,especially when GBs or TBs of mass data are compressed.And ComZip has the potential to beat 7-zip in future as the data window size exceeds 128 MB.     

基于FPGA的激光脉冲编码实现

激光脉冲编码作为半主动激光制导武器提高抗干扰性的重要手段,主要是通过增加编码位数和脉冲间隔时间值的方法实现。本文分析了激光脉冲编码的特点,提出一种基于FPGA利用verilog硬件编程语言实现的编码位数和脉冲间隔均可调的周期脉冲间隔编码设计方案;对该编码方案的硬件结构和编码流程作了详细的介绍;通过功能仿真和实验测试证明了该编码方案的可行性。     

基于子图灰度比较的匹配模板选取算法

为降低图像匹配模板选取算法的时间复杂度,提出一种基于子图灰度比较编码的图像匹配模板选取算法.首先将子图等分为2×2子块,以子图及邻近区域的4×4子块的灰度比较关系为子图赋予一个编码;其次在所有子图编码中选取重复次数最少的编码对应的一个子图或若干个子图中图像方差最大者作为匹配模板.算法复杂度分析和仿真实验结果表明,该匹配...