3G／B3G中多媒体通信数据的健壮性传送

从无线数据业务的发展需要出发，论述多媒体数据健壮性传送的一般性问题和主要技术，进而分析3G MBMS解决方案中采用的数据健壮性传送技术。要确保数据传送的健壮性，应该把多种现有技术加以有机综合运用。作为一个例子，文中描述了一种针对无线分组域多媒体通信中视频数据健壮性传送的通用高效方案。     

Philips演示新技术

philips半导体公司在WinHEC上，实地演示了使用IEEE1394和无线技术进行图像传送的过程。无线技术使用的是美国WiLAN,Inc.开发的Wi-LAN技术，可以用OFDM方式进行市制，使用2.4GHz频带。演示中传送了符号化速度为16Mbps的了两台机顶盒，两台电视机，两台无线传送装后，经由无线传送装置，通过另一个机梵盒同时接收三个频道的图像。Philips演示新技术     

S3C4480X嵌入式指纹数据采集及传输系统

基于ARM的S3C4480X嵌入式指纹数据采集及传输系统．将采集到的指纹图像进行相应的图像处理．然后向服务器传送。服务器可以与原有的数据库信息进行匹配．通过软件获得指纹图像。具体介绍了ARM的软硬件平台，μclinux操作系统，以及无线局域网的无线传输。     

GSM移动通信系统的安全保密性能

介绍ＧＳＭ制式对增强用户信息在无线信道上传送的安全性所采用的各种措施。这些措施，使得用户号码，用户信息都增加了较大的安全性。由于在加密钥也不同。因此，用户信息即使在无线信道传输过程中被截取也较难破译。 ＧＳＭ系统只是在无线基带信号处理过程中进行加密或解密，因此在基站到交换机之间传送信号时处于不加密状态。由于ＧＳＭ并不提供端－端加密，因此对于安全性要求特别高的用户，仍应该在用户终端自行采用端－端加密     

CDPD无线数据传输登陆台湾——全东南亚首个系统 可结合GSM集群通讯GPS

尽管目前手提电话上的各种财经资讯琳琅满目，但使用的人并不算踊跃，原因是以话音传送为主的流动通讯，在传送大量资讯时仍然显得有心无力，无法令用户称心如意，而为了提供更可靠的数据服务，北美一些先进地区又采用了无线数据传送系统，令流动通讯服务更加全面。     

VC—H1无线互动图像通信器

建伍最新推出的VC—H1无线互动图像通信器,采用最先进的数码摄影技术,结合建伍先进的通信器材,可以轻易摄取所需彩色图像,迅速以无线方式传送到所需地点,是世界第一部无线互动通信器。其功能特点如下: 无线传送图像VC—H1无线互动图像通信器,使您能轻而易举地利用无线通信得到清晰的图像传送。传送图像工具简单建伍手机、车机、短波电台均可作为VC—H1传送图像的工具,不受任何环境、地点和时间限制,简单方便。     

SDH技术的现状和发展（下）

ＳＤＨ技术的现状和发展（下）邮电部电信科学技术研究院总工程师邬贺铨５扩展应用领域５．１ＳＤＨ应用传输媒介的扩展在大多数国家传送网都是以光纤为主、无线为辅，为了使有、无线综合应用互为补充，无线系统也往ＳＤＨ方向发展。在无线方式中微波是一种重要的手段，为...     

取代HDMI线缆 Wireless HD公开正式规格

近日面向家用视听设备的毫米波无线规格WitelessHD公开了正式规格．这是一项由韩国LG电子、三星电子、日本松下电器产业、索尼公司等日韩电子产品厂商主导成立的团体制订的标准。WirelessHD是一种旨在实现AV设备间非压缩HDTV影像传送的无线传送规格．目前最初的标准为“Wireless HD Version1.0”。     

无线中继工作者指南＜Ⅰ＞

无线中继工作者指南＜Ⅰ＞［美］ＧｌｙｎＢｏｓｔｉｃｋＲｏｎａｌｄＥ．Ｍｏｈａｒ文金国钧译无线（Ｗｉｒｅｌｅｓｓ）中继与任何预订系统一样，从主发射机方向接收信号，然后放大并向被设定的地区转发信号。无线中继系统用于传送电视节目，在美国和世界各地已很普遍。...     

无线ATM信元传送性能的一种实时测试方法

针对ATM交换机采用无线中继组网的特殊应用情况,从网络开通、运行的角度,提出了一种对无线ATM信元传送性能进行实时测试的方法。这种方法不必单独发送测试信元就可实现与错误有关的无线ATM信元传送性能的准确测量,可为实际无线环境下无线ATM信元的纠错性及网络性能的评估提供重要依据。     

HDLC协议IP核的设计与实现

文中针对专用ASIC芯片实现HDLC协议针对性强,使用不灵活等特点,提出了使用FPGAIP核来实现HDLC接口的设计方案。HDLCIP核包括3个模块：对外接口模块、接收模块和发送模块。IP核接收到新数据后存入接收FIFO,对外接口模块将接收到的数据通过总线将数据送入数据处理单元;当需要发送数据时数据处理单元通过总线将数据存入发送FIFO,启动发送模块将数据送出。接收和发送模块自动完成数据的”插零”及”删零”操作。仿真结果表明该IP核能够正确的接收和发送数据。该方法已在某雷达天线的同步引导数据的收发通信链路中,成功实现了双向数据通信。     

基于DMA引擎的高速网卡的性能分析

随着DMA技术在高速网卡设计中的广泛应用,DMA引擎已经成为网卡提高其和主机间通讯效率的一个重要组成部分。DMA引擎的主要功能是进行主机和网卡之间的接收和发送数据以及描述符的传送。文章进一步清晰了采用DMA引擎的高速网卡的数据接收和发送过程并且建立了采用DMA引擎的高速网卡的数据接收和发送过程的抽象模型。在此基础上,得出了一些有价值的结论。     

基于极化轴比参数的圆极化波发射误差分析方法

简缩极化(CP)模式是一种新型双极化模式。在实际工程应用中，包括简缩极化模式在内的所有双极化模式均无法直接通过外定标的方法补偿发射误差。因而有必要对发射误差所带来的影响进行详细分析。针对极化SAR系统，目前已有学者提出使用误差的最大归一化误差(MNE)参数对极化SAR系统的极化质量做分析评估。该文针对发射圆极化波的简缩极化模式提出了一种基于实际发射极化波极化轴比(AR)参数的发射误差分析方法。首先，通过仿真分析不同发射误差源对AR参数的影响，与此同时还展示了相同发射误差源影响下的MNE参数；通过分析对比，总结了AR参数相对MNE参数的3个优点；最后，使用高分三号卫星的实际测量误差数据与圆极化发射波实验系统的实测数据验证了该文提出的发射误差评估方法的有效性。      

Development of an Error-Correction Method for Data Packet Multiplexed with TV Signals

By using the vertical blanking period of television signals, it is possible to transmit coded data such as teletext, telesoftware, music, etc. However, the quality of data transmission on television transmission channels is very poor and a powerful error-correction code is required to reliably transmit coded data. From the results of simulations using error pattern data collected in field tests and the comparison of various error-correction codes under many conditions, it has been determined that the shortened (272, 190) majority-logic decodable difference-set cyclic code is a suitable code for NTSC TV signals. By using error-correction codes proposed to date for teletext, it has been difficult to obtain a page error rate (PER) of 10^-1in many measurement points. However, PER's of less than 10^-2can be obtained in this system, even when random noise, ghost interference, or waveform distortion are present and bit error rates (BER's) are 10^-2. This paper also gives an empirical equation according to the error data and shows that the error-correction capability increased equivalently up to 11 error-bits in a packet by modifying the decoding algorithm.     

Circular shifted transmit diversity

Three design requirements of space‐time block code, full diversity order, full data rate and orthogonality, cannot be achieved simultaneously when the number of transmit antenna is more than two. In this paper, we propose a transmit diversity scheme—circular shifted transmit diversity (CSTD). CSTD can always achieve the full data rate and has very low decoding complexity. Through the performance analysis and simulation comparison in the case of same spectrum efficiency between CSTD and other well‐known proposed schemes, it can be proved that CSTD always significantly outperforms the other transmit diversity schemes with full data rate. Additionally, compared with the transmit diversity schemes with full diversity order, CSTD has lower complexity and approximately the same performance when channel coding is concatenated. Copyright © 2004 John Wiley & Sons, Ltd.     

An error-correcting code for data broadcasting and its error-correction capability

By using the vertical blanking period of television signals, it is possible to transmit coded data such as teletext, newspaper, telesoftware, music score, etc. However, the quality of ordinary TV channels is very poor for digital communications and a powerful error-correcting code is required to reliably transmit coded data. From the results of simulations using error pattern data collected in field tests and the comparison of various error-correcting codes under many conditions, it has been determined that the shortened (272, 190) majority-logic decodable difference-set cyclic code is a suitable code for NTSC TV signals. Moreover, the decoding algorithm for this code has been improved in order to increase the error-correction capability and a new LSI with this function has been developed. By using error-correcting codes proposed to date for teletext, it has been difficult to obtain a page error rate (PER) of 10⁻¹in many measurement points. However, PERs of less than 10⁻² can be obtained in this system, even when random noise, ghost interference, or waveform distortion are present and bit error rates (BERs) are 10⁻². This paper also gives PERs according to the error-data collected in field tests and shows that the error-correction capability increased equivalently up to 11 error-bits in a 272-bit by improving the decoding algorithm and the results of indoor and outdoor tests.     

协同信道空时优化MIMO无线传输系统

该文提出一种基于虚拟信道的空时优化多输入多输出(MIMO)无线传输系统。通过在发射端产生不同的空时虚拟信道,与实际空间无线信道级联,构成系统的整体传输信道即协同空分信道。系统可以根据接收端的反馈信息采用模拟退火算法来优化虚拟信道,改善误码率(BER)性能。利用虚拟信道方法,可以使一根MIMO发射天线在同一时间、同一频段传输多路叠加合并后的数据信号,从而可以使发射的不同数据信号的总路数超过发射天线的数量,突破了现有MIMO系统在同一时间、同一频段最多只能发射与发射天线数量相等的不同数据信号的传统方式,可以显著提高系统的频谱效率。仿真结果和基于ZC706和AD9361硬件平台的微波暗室实际测试结果充分验证了新MIMO系统的有效性。     

Spatial multiplexing with transmit antenna and constellation selection for correlated MIMO fading channels

We consider spatial multiplexing systems in correlated multiple-input multiple-output (MIMO) fading channels with equal power allocated to each transmit antenna. Under this constraint, the number and subset of transmit antennas together with the transmit symbol constellations are determined assuming knowledge of the channel correlation matrices. We first consider a fixed data rate system and vary the number of transmit antennas and constellation such that the minimum margin in the signal-to-noise ratio (SNR) is maximized for linear and Vertical Bell Laboratories Layered Space-Time (V-BLAST) receivers. We also derive transmit antenna and constellation selection criteria for a successive interference cancellation receiver (SCR) with a fixed detection order and a variable number of bits transmitted on each substream. Compared with a system using all available antennas, performance results show significant gains using a subset of transmit antennas, even for independent fading channels. Finally, we select a subset of transmit antennas to maximize data rate given a minimum SNR margin. A lower bound on the maximum outage data rate is derived. The maximum outage data rate of the SCR receiver is seen to be close to the outage channel capacity.     

V-BLAST系统中一种简单的发射功率分配方案

采用发射功率分配方案可以有效地提高V-BLAST系统的性能。一方面,采用注水发射功率分配方案,可以有效地提高系统容量,另一方面,采用合理的发射功率分配方案,可以在固定数据速率时,改善误码率性能。本文针对第二种应用,给出了一种基于等信干噪比的发射功率分配方案,计算复杂度低,需要的反馈信令少,而且该功率分配方案与调制方式和检测算法无关。通过对MMSE串行干扰抵消和MMSE软干扰抵消检测算法仿真验证,其性能远好于不采用发射功率分配方案,同时接近基于拉格朗日极值法的功率分配方案性能。