数据传输速率高达12.5Gb/s的VCSEL原型

电子制造商Panasonic已经研制出80nm AlGaAs／GaAs（砷化铝镓／砷化镓）垂直共振腔面射型激光器（VCSEL）,为光纤和空间光线传输等低成本光通信提供了解决方案。     

基于OFDM调制和Nyquist滤波的超宽通道大容量光传输

文章首先概述了产生超宽通道的行业背景,接着介绍了产生超宽通道的两种主要方式;分别阐述了OFDM(正交频分复用)调制方式和Nyquist(奈奎斯特)滤波方式的基本原理和产生途径,分析了这两种方式的优劣特点并进行了比较;最后综述了两种方式的研究现状及今后展望。     

Variable rate data transmission with blind rate detection forcoherent DS-CDMA mobile radio

A variable rate data transmission scheme with blind rate detection is described for pilot-symbol-assisted coherent DS-CDMA mobile radio. Cyclic redundancy check (CRC) coding and decoding is used for blind rate detection. Computer simulations of eight-rate variable rate data transmission demonstrate that when 16 bit CRC is used, the loss in required total E_b/N₀ at a frame error rate of 10 ^-2 under two-path Rayleigh fading, is only ~0.1 dB from the known rate case     

从奈奎斯特采样到压缩感知拓展教学方法

从“信号与系统”到“数字信号处理”,采样定理都是重要的教学内容。但是在工程应用中,产生大量数据造成存储空间的极大浪费,而压缩感知突破奈奎斯特采样定理的限制,能够实现远低于奈奎斯特频率的采样。为适应新工科背景下的教学改革,让学生接触前沿研究成果,我们引入压缩感知作为传统教学的补充和拓展,取得良好的教学效果。本文对从奈奎斯特采样到压缩感知拓展教学方法进行介绍。     

Bit error rate performance for edge-detected CMI data transmission

A single edge detector for coded mark inversion, data transmission is proposed. Its detection performance depends mainly on the false transition probability if the bandwidth of the receiver low-pass filter is reasonably large, say equal to twice the data rate. An approximate expression for the bit error rate (BER) performance of this detector operating in white Gaussian noise is derived by considering the level crossing probability of the noise process. Measurements show that this approximation is closer to the actual BER performance than results obtained from a previously established theoretical approach in some cases     

短波低速数据传输关键技术

针对恶劣环境下的军事通信需求,设计了一个直扩-八进制相移键控（DS-8PSK）短波低速数据传输方案。在发送端,用多进制正交扩频来解决频带与信息传榆速率之间的矛盾,设计了一个复合扩频序列提高系统抗干扰性,在接收端,设计了一种改进型Rake接收机来实现分集接收,提高了系统抗多径衰落的能力。最后,用Matlab对数传系统的性能进行仿真验证,仿真结果验证了该方案的有效性。     

具有波特率自适应功能的无线数据传输模块设计

介绍了基于nRF401无线数据传输器件的数传模块的设计与实现,给出了微控制器与nRF401的接口原理图,针对微控制器串行口不足的问题,用软件模拟实现了一个串行口,并得出了51系列单片机波特率自适应功能的定时器初值设定方法,给出了计算公式.     

Acoustic burst transmission of high rate data through shallow underwater channels

Some preliminary results are presented for the transmission of data using two phase DPSK modulation at burst rates of 10 kbit/s over a short distance in shallow water. Average data rates of 1.6 kbit/s were achieved.<>     

Interpolation and extrapolation in nonuniform sampling sequences with average sampling rates below the Nyquist rate

Coefficients for interpolation and extrapolation, including average sampling rates below the Nyquist rate, have been derived. The method is applicable for nonuniform patterns obtained through omission of samples in a uniform pattern with a sampling rate slightly higher than the Nyquist rate. The interpolations and extrapolations are valid for band-limited signals, except those theoretical signals that are zero valued at all sampling points.     

速率自适应透明光传输设备方案设计与实现

提出一种利用8B/10B编码特性实现速率自适应透明光传输设备设计方案,该方案通过控制“控制字符”的插入,使用户时钟信号隐藏在编码后的数据流中,接收端通过解码能恢复出隐藏的用户时钟信号和数据,从而实现速率自适应、透明传输.     

Breaking the Nyquist barrier

The author discusses the concept that data sampled beyond the Nyquist frequency is meaningless. A simple signal processing scheme to extend resolution to nearly twice the Nyquist without the problem of alias emerged. It starts by placing one-dimensional signals into a simulated sample-and-hold process in a Mathcad application     

An effective carrier phase estimation scheme in faster than Nyquist WDM transmission system

We propose a carrier phase estimation method using unequaled digital pilot tone in a faster than Nyquist WDM transmission system, in which the digital pilot tone is employed to estimate laser phase noise induced by the lasers located at the transmitter and the receiver ends. The method can effectively overcome the scale of the inter-symbol interference introduced by FTN signaling, with the good features of high phase noise tolerance and simple hardware complexity.     

利用空时分组编码技术提高数据传输速率的研究

未来的通信对移动通信业务的要求越来越高，随着从单纯语音业务到多媒体业务的转变，通信中数据传输速率成为抑制日后发展的因素之一。因此人们努力研究各种高效的编码、调制以及传输的技术，用以提高数据的传输速率。空时编码是近年提出的重要技术之一，这种技术已经在第三代移动通信(3G)方案中广泛应用。本文在介绍简单的空时分组编码原理的基础上，着重研究了对共道信号产生的干扰进行抵消抑制的技术。采用具有干扰抵消技术的空时分组编码系统进行并行数据传输可以充分利用干扰信号之间的相关性进行有效的抵消处理，在原有的信道上能够极大的提高数据的传输速率。文中提出了一种利用多种调制方式抗干扰性能的不同，对共道信号进行分步解码来削弱共道干扰的影响的空时分组编码并行传输策略。这种方法能够进一步提高信号传输的性能，为提高通信系统的数据传输速率做出了保证。     

A near‐Nyquist rate transmission: A new minimum‐bandwidth direct‐sequence code division multiple access scheme

Bandlimited direct‐sequence code division multiple access (DS‐CDMA) attracts much attention for its compact spectrum and the ability to suppress inter‐symbol interference. Among the various bandlimited DS‐CDMA systems available, minimum‐bandwidth DS‐CDMA (MB‐DS‐CDMA) is the only realizable Nyquist rate transmission system. But, MB‐DS‐CDMA only applies to certain kinds of spreading codes. Accordingly, this study proposes a modified DS‐CDMA structure which extends the application of MB‐DS‐CDMA to all common spreading codes at the expense of a negligible reduction in the transmission rate. Additionally, the bit error rate of the proposed schemes adopting either single‐user or multi‐user detection receiver is analyzed and compared with that of the commonly‐used raised‐cosine‐pulsed DS‐CDMA over multipath fading channels. The numerical results show that given a sufficiently large number of users, the bit error rate performance of modified MB‐DS‐CDMA is comparable to that of the raised‐cosine‐pulsed DS‐CDMA scheme; meanwhile, the realizable modified MB‐DS‐CDMA approaches the ultimate transmission rate.     

一种遥感卫星高码速VCM数传信道的均衡技术

在基于第二代数字卫星视频广播协议（DVB-S2）标准的遥感卫星可变编码调制（VCM）高码速数传信道中,宽带信号的大失真、大频偏和低信噪比会导致解调器载波环路不锁定。传统的DVB-S2解调器并不能解决这个问题。在载波环路前增加一个均衡器补偿失真,可以让载波环路稳定锁定。为了克服载波环路前信号的频偏和相偏对均衡器的影响,提出了一种均衡技术,利用起始序列（SOF）和导频的先验信息进行双重自相关变换,设计了一种新的误差函数和迭代过程。仿真结果表明,该均衡技术可在该应用条件下支持解调稳定工作。     

Image transmission over mobile Bluetooth networks with enhanced data rate packets and chaotic interleaving

Bluetooth is a wireless personal area network. This type of networks is widely used for image communication. This paper presents a study for the transmission of images over mobile Bluetooth networks. It presents a novel chaotic interleaving scheme for this purpose. In this scheme, the chaotic Baker map is used for bit interleaving and enhanced data rate packets are used for data transmission. In the proposed scheme, the chaotic interleaver can be applied on the whole bit stream or on a packet-by-packet basis. The proposed scheme is applied with 2DH₁, 2DM₁, 3DH₅, and 3DM₅ packets. A comparison study between the proposed scheme and the traditional interleaving schemes for image transmission over correlated and uncorrelated fading channels is presented. The simulation results show the superiority of the proposed scheme over the traditional schemes. The proposed scheme also adds a degree of security to data transmission.     

基于Nyquist脉冲副载波调制的短距离光纤传输技术研究

提出了一种适用于强度调制直接检测(IM/DD) 光系统的信号调制格式。这种基于Nyquist脉冲half cycle副载波调制(SCM)信号能有效提高频谱效率,为了减少传递函数引起的系统的性能 恶化,采 用了数字预均衡和后均衡实现对光纤损伤的补偿;建立了偏振复用(PDM)IM/DD系统 平台, 分析了Nyquist脉冲SCM信号在系统中的PAPR性能,实现了72Gbit/s 64-QAM N yquist脉冲SCM信号经过20km标准单模光纤(SMF)传输后其误码性能 小于前向纠错(FEC)阀值3．8×10－3。     

Maximizing the data transmission rate of a cooperative relay system in an underwater acoustic channel

In this paper, we investigate the problem of maximizing the data transmission rate of a cooperative relay system in an underwater acoustic communication channel. With amplify‐and‐forward relaying and adaptive source transmission, we present optimal transmit signal power adaptation policies that maximize the data transmission rate, considering both frequency and time domains. The analysis takes into account a physical model of acoustic path loss and ambient noise power spectral density. Typical characteristics of underwater channel such as frequency‐dependent fading and time variations are also considered. Capacity bounds for channel state information (CSI) only at the receiver and CSI at both transmitter and receiver are presented. To maximize the data rate, we use the notion of an optimal bandwidth which corresponds to efficient allocation of signal power across the transmission bandwidth. Under the constraint of an average transmit power, the optimal transmit power adaptation policy is found to be ‘water‐pouring’ in frequency‐time domain, while the transmit power adaptation policy with a total power constraint is ‘water‐pouring’ in frequency domain. Results show that both frequency domain and frequency‐time domain power adaptation schemes provide much greater improvement in average data rate over that of the constant power case. Copyright © 2011 John Wiley & Sons, Ltd.     

Exploding the Nyquist barrier misconception

The author comments that Smith (IEEE Signal Processing Magazine, Forum Feedback, May 1996) continues to proclaim the novelty of an approach (Smith, 1995) that he purports to “break the Nyquist barrier,” in spite of the revelation (Marple Jr., 1996) that his approach is simply a special two-filter case of well known analysis and synthesis filter banks performed with sample-and-hold waveforms. Smith's Fig.4(b) in Smith (1995) can be compared with the conventional filter banks of Fig.4 in Marple Jr. (1996) and it is observed that they are identical. Smith also makes further observations to which the present author responds with additional commentary. However, the primary purpose of this contribution is to expose a fundamental misconception regarding the universality of the sampling theorem as taught in most digital signal processing textbooks. It is this misconception that led Smith to prematurely claim victory over a perceived impenetrable Nyquist barrier