分类：设计开发    下载：0    浏览：235    时间：2017-07-29

Channel-Adaptive Resource Allocation for Video Transmission over 3G Wireless Network

分类：设计开发    下载：0    浏览：346    时间：2017-07-29

Third-Generation and Beyond (3.5G) Wireless Networks and Its Applications ABSTRACT This paper first describes the applications of 3G and beyond wireless networks and general trends. To address these advanced applications, WCDMA HSDPA promises to provide services of up to 10Mbps and higher spectral efficiency for packet data. It represents a major evolution of the air interface since 1997 when the concept of 3G was adopted. We can called it “3.5G” in this paper to differentiate the fundamental difference between 3G and 4G. For 4G, it is believed that the air interface of the 4G wireless network will be different from that of the 3G. The basic concept and principles of WCDMA HASDPA are discussed in the paper.

分类：设计开发    下载：0    浏览：258    时间：2017-07-29

摘要：分析了具有代表性的无线传感器网络操作系统TinyOS的调度机制并指出其不足。在此基础上提出了改进方案并实现了基于优先级的调度策略。从模拟仿真及在实际系统GAINS节点中应用的结果可知，该改进方法能很好地改善无线传感器网络通信性能。 关键词：无线传感器网络；TinyOS；调度策略；优先级

分类：设计开发    下载：0    浏览：264    时间：2017-07-29

摘要：在对数字家庭网络分类和现状分析的基础上，针对家庭控制网络，提出了一种分布式无线数字家庭控制网络的实现方案。介绍了数字家庭控制网络的总体结构，提出了网络的协议参考模型和家庭网关的构成及在远程控制中的应用设计，并指出下一步的研究方向。 关键词：家庭控制网络；协议参考模型；家庭网关；远程控制 Study and Design of Distributed and Wireless Home Control Networks YAN Jun1, WANG Xin2 （1. Communication and Information Engineering School, Shanghai University, Shanghai 200072; 2. Department of Computer Science and Engineering, Fudan University, Shanghai 200433) 【Abstract】This paper classifies a digital home network and analyzes its research status. About home control networks, it presents a scheme ofdistributed digital home control networks. It introduces its structure, proposes network protocol stack model, the composing of a home gateway andthe application design of remote control. Finally, it points out the next step work. 【Key words】Home control network; Protocol reference model; Home gateway; Remote control

分类：设计开发    下载：0    浏览：318    时间：2017-07-29

翟临博，张晓敏 (山东大学信息学院，济南 250100) 摘要：提出了一种在非理想信道下分析IEEE 802.11无线局域网的饱和吞吐量的方法。分析的过程中考虑到信道“捕获”和退避“冻结”的问题，采用条件概率建立了数学模型。在IEEE 802.11b无线局域网定义的不同数据速率下，利用该方法对基本访问机制和RTS/CTS访问机制进行了分析。仿真表明，分析结果与DCF模式下的饱和吞吐量是吻合的。 关键词：802.11；802.11b；无线局域网；饱和吞吐量 Performance Analysis of Wireless LANs for Lossy Channel ZHAI Linbo, ZHANG Xiaomin (Information College, Shandong University, Jinan 250100) 【Abstract】This paper presents a way to estimate the saturation throughput of IEEE 802.11 for a lossy channel. The analysis which isinvolved incapture effects and backoff freezing procedures, is based on elementary conditional probability arguments. It uses this way to analyze theperformance of the basic access and RTS/CTS access mechanisms of IEEE 802.11b. Simulation results show the analysis accurately predicts thesaturation throughput in DCF mode. 【Key words】802.11; 802.11b; Wireless LANs; Saturation throughput

分类：设计开发    下载：0    浏览：308    时间：2017-07-29

高昊江，杨 晟，张宜生，梁书云 (华中科技大学模具技术国家重点实验室，武汉 430074) 摘要：恶劣环境下无线信号会出现时断时续的不稳定现象，导致传统的保持在线连接的通信方法不能正常工作。为此，提出了一种“信号－时间窗”分析指引下的基于FTP协议传送经混沌加密及压缩处理的XML文档的数据通信策略，给出了其在恶劣信道下成功应用的实例。系统投入运行半年多的实践结果表明，该通信策略能很好地解决恶劣环境下的数据通信问题，保证了通信的敏捷性、完整性、保密性和可靠性，在恶劣通信条件下或异构系统之间的数据通信领域具有相当的应用价值和参考意义。 关键词：恶劣环境；数据通信策略；混沌加密；XML；系统安全 Research and Application of Wireless Network Data Communication Strategy in Adverse Environments GAO Haojiang, YANG Sheng, ZHANG Yisheng, LIANG Shuyun (State Key Lab of Plast. Form. Simulation, Huazhong University of Science and Technology, Wuhan 430074) 【Abstract】In adverse environments, wireless communication speed is slow and often breaks down. It causes the traditional keeping-in-connectioncommunication methods do not work. To resolve this problem, a communication strategyis presented, which uses signal time window and FTP totransmit chaotic-encrypted and compressed XML document. The application example is also given, which has been put to use for more than half ayear. The experiments and application results show that the proposed communication strategydoes good work at bad communication conditions, andhas the advantages of agility, completeness, security and stability, which can be widely applied in the data communication fields under badcommunication conditions or between different systems. 【Key words】Adverse environments; Data communication strategy; Chaotic encryption; XML; System security

分类：设计开发    下载：0    浏览：323    时间：2017-07-29

张文柱, 李建东, 王　炫 (西安电子科技大学信息科学研究所,陕西西安　710071) 摘要: 基于场景用仿真方法研究了3 种适用于分布式无线网络的路由协议及其网络性能. 仿真结果表明,当通信半径一定时,3 种路由协议的网络性能均随着网络中节点运动速度的提高而变差;当节点运动速度一定时,3 种路由协议的网络性能均随着节点通信半径的增加而变好;同等条件下,Ad2hoc 按需距离矢量路由协议的端到端通过量高于动态源路由协议和目标序列距离矢量路由协议,分组丢失率低于动态源路由协议和目标序列距离矢量路由协议,而目标序列距离矢量路由协议的平均分组传输时延保持最低. 关键词: 分布式无线网络;路由协议;网络性能

分类：设计开发    下载：0    浏览：492    时间：2017-07-29

段中兴1,2，张德运1 (1. 西安交通大学电子与信息工程学院，西安 710049；2. 西安建筑科技大学信控工程学院，西安 710055) 摘要：为了提高IEEE 802.11中速率选择机制的性能，提出了一种基于多信道参数数据融合算法的自动速率选择机制，克服了采用单一参数进行信道状态估计的误差和误判。在发送端，将获取到的RSS、CIR和PER信息模糊化，并运用模糊集理论进行模糊推理，形成单一参数对信道质量评估的局部决策，经过融合中心的合成运算和决策规则得到信道质量的全局判决，以此进行最佳发送速率的选择。该算法在NS2网络仿真软件的Ricean信道模型下进行了仿真。仿真结果表明该机制比固定速率和单一参数信道估计机制提高了28.4%和22.2%的平均吞吐量。 关键词：无线局域网；数据融合；速率自动选择；模糊评判 Rate Adaptation Algorithm in Multi-rate WLAN DUAN Zhongxing1,2, ZHANG Deyun1 (1. School of Electronics and Information Engineering, Xi’an Jiaotong University, Xi’an 710049; 2. School of Information and Control Engineering, Xi’an University of Architecture and Technology, Xi’an 710055) 【Abstract】A data fusion algorithm is adopted to enhance the performance of auto rate selection mechanism in IEEE 802.11 based on fuzzy systemtheory, and with the application of this mechanism, the misjudgement of channel state which estimated by single channel parameter is eliminated. Insender, the received signal strength (RSS) and carrier to interface ration (CIR) and packet error ratio(PER) value that sensors obtain is fuzzed, andeach of them is used by fuzzy logic control to make part judgement about the channel quality. The best rate is selected based on the decision whichobtained through the synthetic operation and decision rule of the data fusion center.Simulation results show that the mechanism enhances meanthroughput performance of IEEE 802. 11 system compared with that presented in the literature. Compared with the fixed transmit rate mechanism,the enhancement reaches 28.4 % , and with the single parameter estimated mechanism, the enhancement reaches 22.2 %. 【Key words】Wireless local area network(WLAN); Data fusion; Auto rate selection; Fuzzy assessment

分类：设计开发    下载：6    浏览：458    时间：2017-07-29

张 强，赵 政 (天津大学电信学院，天津 300072) 摘要：提出了一种基于地理位置信息的无线网络路由协议LADRU，以增强高移动性网络TCP的性能。协议采用单播和广播相结合的礼花式广播来减少系统开销，以随机竞争方式探测路由，减少寻找新路由的代价。通过估计网络节点的运动速率来自动调节路由探测周期，使路由得到及时更新。采用标签路由方法传递数据包，解决源路由方式数据包头过大和路由切换问题。仿真结果表明LADRU能有效地提高数据传输率和系统吞吐率。 关键词：TCP；地理位置；随机竞争；标签路由 Routing Protocol for TCP in High Mobility Ad-hoc Networks ZHANG Qiang, ZHAO Zheng (School of Electronic Information Engineering, Tianjin University, Tianjin 300072) 【Abstract】A geographical location based routing protocol is presented to augment TCP performance in high mobility wireless ad-hoc networks.This paper introduces a skyrocket broadcast by the integration of unicast and broadcast, which can drop system overhead. A new routing detectionmethod is introduced based on random competition, which reduces the cost of routing discovery. The routing can be updated in time throughperiodic routing detection whose interval is adjusted automatically according to the estimation of nodes’ speed.The data packets are transmitted by anew label routing method that can reduce the packets’ head and make it easy to switch to a new routing. The simulation shows that LADRU canincrease delivery ratio and throughput of TCP. 【Key words】TCP; geographical location; random competition; label routing

分类：设计开发    下载：0    浏览：289    时间：2017-07-29

摘要 IEEE802.11b( 研究表明! 只要重叠或相邻C11 小区中心频率相距%E2/0 以上! 就可以有效避免同频或邻频干扰" 在C11 小区密集地区! 需要严格的频率规划" 提出并实现适用于IEEE802.11b( 的一种抗干扰自适应频率规划机制" 测试表明! 在无严格频率规划条件下! 该机制能抗同频或邻频干扰和其它窄带信号干扰改善性能" 关键词:WLAN  抗干扰自适应频率规划

分类：设计开发    下载：2    浏览：424    时间：2017-07-29

刘军, 郭伟, 肖百龙, 黄飞 ( 电子科技大学通信抗干扰技术国家级重点实验室, 四川成都610054) 摘要: 通过分析IEEE 802. 11 DCF 的分组发送过程, 获得了RTS 和基本方式下分组传输的时间开销。给出了以最小化传输时间开销代价为优化目标的最优RTS 门限的计算公式。通过对当前信道分组发送的成功概率Ps 的预测, 实现了最优RTS 门限的计算, 并给出了一个具体的自适应RTS 门限调整算法, 使终端能自动调整其RTS 门限以达到或接近最优值。仿真表明自适应RTS 门限调整算法有效减小了MAC 分组传送的时间开销, 提高了信道的传输效率。 关键词: 无线局域网; 802. 11 DCF; RTS 门限; 分组成功传送概率; 自适应RTS 门限调整

分类：设计开发    下载：0    浏览：416    时间：2017-07-29

初建朋，李小进，赖宗声 (华东师范大学微电子电路与系统研究所，上海 200062) 摘 要：分析了802.11a无线局域网(WLAN)OFDM基带接收系统中频率同步和信道估计算法的运算特点。针对实际算法的特点，设计了一个面向应用的专用DSP处理器(ASP)，利用ASP可以以软件方式实现802.11a前导序列的接收。经实际流片验证表明，该设计可以实现11a前导序列接收的各种基带处理运算，具有高度的灵活性和较小的芯片面积。 关键词：正交频分复用；软件无线电；面向应用数字信号处理器；软硬件协同设计；无线局域网 Analysis and ASP Realization of 802.11a Frequency Sync. and Channel Est. CHU Jianpeng, LI Xiaojin, LAI Zongsheng (Institute of Microelectronics Circuit & System, East China Normal University, Shanghai 200062) 【Abstract】This paper analyzes the calculation cost and characteristics of 802.11a preamble receiving. Realization of these algorithms using SDR,which is based on an application specific DSP and S/W codesign, is introduced. An effectively DSP processor architecture is designed. The testresults show this design is able to implement 11a baseband process effectively and flexibly. 【Key words】OFDM; SDR; ASP; SW/HW codesign; WLAN