无线传感器网络MAC层协议的对比研究

无线传感器网络是二十一世纪新兴的网络技术，它的出现使网络的发展进入一个新的阶段。针对无线传感器网络MAC层协议的研究一直是人们普遍关注的问题。总结了近年来的研究成果并针对TDMA，IEEE802．15．4，S—MAC，T—MAC几种典型的MAC层协议进行了对比分析，根据其各自的优点提出将来工作的方向和建议。     

单小区模型的掉话率分析

掉话率是无线通信网络中最重要的关键性能指标(KPI)之一,本文分析了中国移动在讨论网络性能评估方法时提出的3个不同的掉话率计算公式,通过建立一个单小区的模型,使用一些合理的假设和分析,从理论上确定了一个最为准确的计算公式.     

基于数字CATV的超宽带技术研究

如何利用现有的数字CATV系统开展各种增值业务已成为一个重要课题.首先简要介绍了数字CATV和超宽带技术,然后给出了两种超宽带技术在现有数字CATV系统中的应用方案,利用这些方案可以有效地开展各项增值业务.     

Mobility Influences on the Capacity of Wireless Cellular Networks

Capacity has always been a major concern in wireless networks. This letter studies the impact of mobility on the overall system capacity in wireless cellular networks. In this letter, we present a simple system model which we developed to capture the inherent relationships among system capacity, new call blocking probability, handoff dropping probability, call terminating probability, and bandwidth utilization rate. We investigate the complex relationship between mobility and capacity‐related parameters. Through simulation, we demonstrate that mobility has a significant impact on capacity and is reversely proportional to the bandwidth reserved for handoff traffic.     

基于多信道预约可冲突避免的多址接入协议

本文为多跳分布多无线网络提出了一套灵活而有效的自适应获取冲突避免（AACA）的多址接入协议。在该协议中，各节点竞争公共信道，利用RTS/CTS对话形式来预约各业务信道，成功预约后的分组传输不会受到其他节点的干扰。它使用任意确定数目信道，以异步方式工作，并且使得各节点利用半双工无线电台就可以灵活、简便地实现资源预约。分析和比较结果说明，所提出的多信道预约协议可以有效地解决隐藏终端、暴露终端以及侵入终端的问题。     

井口信号无线数传系统

目的　介绍了井口信号无线数传系统的设计 .方法　无线数传、低功耗电路设计 .结果　省去了井口信号线 ,降低了井口工作量 .结论　提高了测量精度和可靠性     

无线传输有线接入钻井数据库管理系统

本文详细的介绍了无线传输有线接入钻井数据库管理系统的设计和实现过程,同时对系统体系研制思路及关键技术,数据库系统结构、功能及特点等进行了阐述。通过应用该钻井数据库管理系统,管理者能够迅速、准确、全面、及时地掌握全油田钻井生产状况和钻井生产系统内部的钻井生产物料、资金等的使用情况,以便增强钻井生产系统的应变能力,提高钻井生产管理水平,从整体上提高全油田生产效率、生产资金的利用率,达到提高经营效益的目的。     

Reconfiguration Aspects and a Reconfigurable Outer Block Interleaver for 3G Applications

Reconfiguration concept represents reconfigurable functionalities of the radio interface for mobile radio systems. Particularly for the physical layer, some possible reconfigurable architectures can be identified. We focus on outer interleaving for turbo codes, which can improve their performance in flat Rayleigh fading environment. The larger the number of columns in the outer interleaver, the better is the performance, but with the penalty of more complexity and delay. Furthermore, an incorrect choice of the number of columns can increase the bit and frame error rates. Therefore, it would be advantageous to reconfigure the outer interleaver in different operating environments with the optimum number of columns. Using two different data frame lengths, in this contribution simulation results are presented for the four possible outer block interleaver configurations specified for the 3GPP mobile standard in the case of flat Rayleigh fading channel. It is shown that different operating environments require an optimum number of columns in terms of bit error rate and frame error rate performance. Finally, frame fade duration is considered and the effect of the product of the Doppler frequency with the frame duration on the performance for the four different 3GPP outer block interleaver configurations is discussed. Costas Chaikalis was born in Athens, Greece, on March 7, 1973. He received the B.Sc. degree in electrical engineering in 1995 from Technological Educational Institute of Lamia, Greece. He also received the M.Sc. and Ph.D. degrees from Department of Electronics and Telecommunications, University of Bradford, Bradford, UK in 1999 and 2003, respectively. During his doctoral studies he worked as a Research Assistant for Mobile Virtual Center of Excellence (Mobile VCE), Terminals Group, UK. Since 2003, he is a lecturer in the Department of Electrical Engineering, Technological Educational Institute of Lamia, Greece. His research interests are in all areas of mobile communications but especially in forward error correction coding, reconfigurable (software radio) architectures, cross layer architectures and DSP applications.     

局域网语音实时传输的实现

语音实时传输是语音聊天软件的核心技术。文中在分析语音实时传输原理的前提下,探讨了局域网语音实时传输的设备的初始化、内存分配、语音录制、播放和传输等具体方法,并以C Builder6.0提供的控件为基础,以API函数给为工具,给出了局域网实时语音聊天的具体实例,实现了局域网用户间的语音实时传输。     

GPRS无线DDN系统与应用

介绍基于GPRS网络无线DDN系统的构成、组网以及在电力系统的应用，同时对传输包长度、效率、时延等参数进行分析。