EEFA:高能效的IEEE 802.11N帧聚合调度算法(英文)

Packet size is restricted due to the error-prone wireless channel which drops the network energy utilization.Furthermore,the frequent packet retransmissions also lead to energy waste.In order to improve the energy efficiency of wireless networks and save the energy of wireless devices,EEFA(Energy Efficiency Frame Aggregation),a frame aggregation based energy-efficient scheduling algorithm for IEEE 802.1 In wireless network,is proposed.EEFA changes the size of aggregated frame dynamically according to the frame error rate,so as to ensure the data transmission and retransmissions completed during the TXOP and reduce energy consumption of channel contention.NS2simulation results show that EEFA algorithm achieves better performance than the original frame-aggregation algorithm.     

一种无线宽带收发机I/Q失配校准和补偿技术

本文提出一种基于数字基带的无线宽带收发机中的发射链路I/Q失配的校准和补偿技术。数字基带发射用于I/Q失配校准的信号,经过RF收发机的发射链路、由平方功率检测器、带通滤波器组成的校准通路以及RF接收机的可变增益放大器,数字基带采集此信号并估计I/Q失配的大小,完成I/Q失配的校准和补偿,此技术相比于射频的自校准节省了面积和功耗。本技术已经成功用于IEEE802.11n,可以实现50dB以上的镜像抑制,完全满足了系统要求。     

MST-based topology control with NLOS location error compensation for location-aware networks

The topology control algorithms can improve the network capacity and network lifetime in location-aware networks. The topology control algorithms require accurate locations of mobile nodes or distances between each of the mobile nodes. The IEEE 802.15.4a-based location-aware networks can provide precise ranging distance between two mobile nodes. The mobile nodes can obtain their accurate locations by using accurate ranging distances. However, in the IEEE 802.15.4a networks, the ranging distance has a large measurement error in non-line-of-sight (NLOS) conditions. In this paper, we propose MST-based topology control with NLOS location error compensation algorithm to improve location accuracy and prevent mobile nodes from connecting to unstable links in NLOS condition. Performance evaluation shows the proposed algorithm constructs a topology map which has low location errors with considering the instability of NLOS links in NLOS condition.     

CBTC系统无线通信监测软件的研究和开发

本文针对列车运行控制系统的无线通信在ISM 2.4G频段内易受干扰的问题,提出一种满足实际需求的简化监测开发方案,对分析列车控制系统的无线通信具有重要意义.通过对监测软件的架构和信令交互进行分析,给出监测软件的主流程,并完成软件的开发.该软件已投入到北京地铁CBTC系统无线通信的现场测试中,测试结果证明监测软件具有完整、准确的测试能力.     

IEEE802.16d下一种改进的打孔卷积编码算法及FPGA实现

分析了信道编码在正交频分复用（OFDM）系统中的作用,重点研究了卷积编码原理和具体实现。参考IEEE802.16d标准,结合现有多码速率编码算法,提出了一种新的打孔算法,仿真实验表明该算法降低了系统的误码率;可编程逻辑器件（FPGA）上的硬件在线调试表明实测结果和算法仿真结果吻合,且在提高可靠性的同时,节省了硬件资源。     

利用互联网资源进行通信领域技术的检索

检索是专利审查过程中的重要环节,检索数据库的选择与使用直接决定了检索效率和准确性.互联网资源的合理使用对于专利申请的检索有着重要的意义,结合通信领域的三个实际案例,分别介绍了IEEE论文库、3GPP协议库以及patentics语义检索数据库的使用方法以及特点.以便申请人利用免费的互联网资源能够针对专利申请文件进行更便捷、更准确和更全面地检索.     

人体局域网的MAC层分析与研究

在分析人体局域网的背景和研究现状的基础上,指出MAC协议是影响人体局域网整体性能的关键技术之一.总结分析MAC层协议的研究现状,并对IEEE802.15.6标准中定义的MAC协议进行详细的探讨,进而分析了BAN的网络拓扑结构.最后,对人体局域网MAC协议研究中面临的挑战进行讨论,给出MAC协议未来的研究方向.     

Distributed Borrowing Addressing Scheme for ZigBee/IEEE 802.15.4 Wireless Sensor Networks

This paper proposes a distributed borrowing addressing (DIBA) scheme to solve problems of failure in address assignments resulting from limited tree depth and width when the distributed address assignment mechanism is used in a ZigBee/IEEE 802.15.4 wireless sensor network. DIBA is a method of borrowing addresses from neighbor nodes for newly entering nodes and assigning the borrowed addresses. Its network or sensing coverage can increase with almost the same overhead as the existing method. DIBA is a simple and lightweight means of addressing and routing, making it suitable for wireless sensor networks. Simulations showed that DIBA is a distributed addressing scheme with consistently excellent performance.     

WLAN优化研究

最近几年,无线局域网已经在学校、宾馆、商业楼宇、医院等场合得到了广泛应用.为保证WLAN建设高密度场景用户使用的效果与最终体验,势必要对W LAN进行优化,以满足日益扩大的业务发展需要.     

802.1x协议在办公内部网络中的应用

本文通过介绍802.1x协议在办公内部网络中的应用,拟在帮助读者对内部网络与外部网络有更深入的认知,并提高对网络安全问题的警惕性。