Interleaved coding and sequential transmission scheme for packet‐level forward error correction over burst loss channels

Burst packet loss is a common problem over wired and wireless networks and leads to a significant reduction in the performance of packet‐level forward error correction (FEC) schemes used to recover packet losses during transmission. Traditional FEC interleaving methods adopt the sequential coding‐interleaved transmission (SCIT) process to encode the FEC packets sequentially and reorder the packet transmission sequence. Consequently, the burst loss effect can be mitigated at the expense of an increased end‐to‐end delay. Alternatively, the reversed interleaving scheme, namely, interleaved coding‐sequential transmission (ICST), performs FEC coding in an interleaved manner and transmits the packets sequentially based on their generation order in the application. In this study, the analytical FEC model is constructed to evaluate the performance of the SCIT and ICST schemes. From the analysis results, it can be observed that the interleaving delay of ICST FEC is reduced by transmitting the source packets immediately as they arrive from the application. Accordingly, an Enhanced ICST scheme is further proposed to trade the saved interleaving time for a greater interleaving capacity, and the corresponding packet loss rate can be minimized under a given delay constraint. The simulation results show that the Enhanced ICST scheme achieves a lower packet loss rate and a higher peak signal‐to‐noise‐ratio than the traditional SCIT and ICST schemes for video streaming applications.     

基于DC-net的会议室电子选举方案

提出了一种新的适用于小规模选举活动的电子选举方案,其最大特点是能够提供无条件的完美选票秘密性保障。方案具有自计票功能,能够实现公平性和可验证性。敌手对选举结果的破坏等同于解离散对数问题。该方案建立在DC-net匿名广播协议基础之上,其安全性不依赖于任何信任中心,但需假定任意投票者之间存在秘密信道。     

基于ICE1CS02的PFC＋PWM电路设计

基于ICE1CSO2设计了一种PFC＋PWM电路。采用前级为PFC电路,后级为双管正激拓扑电路的方式。通过仿真分析电路的基本原理,以500 W电路为例对PWM部分主变压器进行了详细的设计,并通过实际电路验证此电路具有功率因数高、稳定、高效等优点。     

高速超长距离光纤通信系统中的新型技术

给出了超长距离高速光纤通信系统的定义;介绍了高速超长距离光纤通信系统的特征;综述了高速光纤通信系统在光放大器、色散补偿、前向纠错等方面的最新技术.最后,论述了制订或修订相关国际标准的必要性.     

Performance analysis and power allocation for decode‐and‐forward cooperative communications over Rician fading channel

This paper derives the asymptotic symbol error rate (SER) and outage probability of decode‐and‐forward (DF) cooperative communications over Rician fading channels. How to optimally allocate the total power is also addressed when the performance metric in terms of SER or outage probability is taken into consideration. Analysis reveals the insights that Rician factor has a great impact on the system performance as compared with the channel variance, and the relay–destination channel quality is of importance. In addition, the source–relay channel condition is irrelevant to the optimal power allocation design. Simulation and numerical evaluation substantiate the tightness of the asymptotic expressions in the high‐SNR regions and demonstrate the accuracy of our theoretical analysis. Copyright © 2011 John Wiley & Sons, Ltd.     

人工噪声辅助的多用户安全传输方法

针对传统人工噪声辅助的安全传输方法无法适用于发射天线数等于接收天线数的多用户(Multiuser, MU)多输入多输出(Multiple-Input Multiple-Output, MIMO)系统的问题,提出了一种人工噪声辅助的多用户安全传输新方法。通过合理设计人工噪声与预编码矩阵,该方法可在同时满足所有用户传输需求的基础上,显著提升发射天线数等于接收天线数的MU-MIMO系统的安全性。同时,针对提出的方法进行了检测算法与平均保密速率的推导与分析。理论分析与仿真结果表明,所提方法可有效提升无线通信系统的安全性,在信噪比为20 dB时,该方法较传统方法的平均保密速率提升达到120%。     

SISAR中运动目标全息信号的模拟研究

运动目标的无线电全息信号的表示是基于光学的衍射原理与近似处理的方法获得的.对全息信号模拟研究的目的是验证和改进理论分析方法,模拟产生的运动目标的全息信号可直接应用于阴影逆合成孔径雷达(SISAR)的成像研究和目标识别研究中.为此,文中导出了一种由目标侧影轮廓及其运动参数模拟其全息信号的方法.按外场试验条件模拟产生了两个目标的全息信号, 并分别与外场实际获得的同目标的全息信号进行了比较,结果表明该模拟及分析方法有效.     

基于fan4800C的正激式开关电源的设计

介绍了一种基于fan4800C的双晶正激式多路输出AC/DC的开关电源的原理与设计方法。分析了fan4800C的特性和工作原理,并给出了它的设计原理框图及具体设计过程,最后给出了该电源模块的实测波形及测试技术指标。     

一种光输出功率控制电路

分析了光输出功率控制在光通信中的重要性 ,提出了一种有效的光功率控制电路。实验结果表明 ,该电路对调节和稳定光输出功率非常有效。     

一种安全的公共认证电子拍卖方案

利用Bit承诺,单向函数和数字签名算法,对一种安全电子拍卖模型进行改进,提出了一种安全、简单、高效的密封式电子拍卖方案.它可以在注册中心离线的情况下,最大程度地缩小拍卖行的权力实现公共认证.同时,该方案不仅能对除中标者外的其他所有投标者的投标价进行保密,而且能有效防止拍卖行不诚实的行为.