移动通信中的中继技术研究

GSM网络中使用的中继技术主要是直放站的形式,这种中继方式对接收信号做的处理是直接放大然后发射,也就是Amplify-Forward即AF方式。还有一种中继方式叫做Decode-Forward即DF方式,这种方式将在下一代移动通信系统中广泛使用。在AF策略中,中继仅仅将收到的信号放大然后发送到接收端;在DF策略中,中继对收到的信号进行解码并重新编码,然后将其发送到接收端。研究这两种基本的中继技术具有重要的科研意义。与以往分析不同,本文通过matlab仿真,分析了在不同信道和编码情况下AF、DF两种中继方式的性能,研究了二者的实际性能和所面临的问题。     

基于无线中继的宽带接入模型研究

随着无线通信技术的发展,现有的WiMAX系统由于存在着覆盖有盲区和系统容量不足等问题,不能很好满足新一代无线通信系统更高传输速率、更好信号覆盖和更好移动性的要求,需要一种新的部署方法来解决。在对无线中继技术进行相关分析的基础上,提出基于IEEE802.16j的宽带接入参考模型和协议栈,并进行中继多跳接入和单跳接入掉话率的仿真比较,结果表明中继接入可以在降低系统成本的同时有效提升系统的性能。     

基于议价博弈论的无线协作中继网络性能改进算法

针对自私性无线协作中继(CR)网络中的放大再中继(AF)和解码再中继(DF)协议,分别给出 公平且有效率的协作中继功率分配方案。两种方案虽然具体研究内容有差别,但有着共同 的研究策略。首先,将节点间的协作功率选择问题建模为纳什议价博弈问题(NBP);然后, 通过求取其纳什议价解(NBS)获得协作节点的共赢策略;最后,针对AF和DF协议分别给出计 算机仿真。仿真结果表明,所提出协作中继性能改进算法的效率性体现在所有协作节点在AF 和DF协议中均获得信号接收质量的提高,其公平性则体现在任意节点为其协作伙伴所贡献的 转发功率大小仅取决于对方为其带来的性能增益大小。     

应用于第三代移动通信系统中的中继技术

分析了一种可应用于TD-SCDMA蜂窝移动通信系统的中继技术.该技术将Ad hoc和蜂窝系统相结合.在蜂窝移动通信系统中,移动台和基站之间的信号可以通过其他移动台转发.这种中继技术可以减少小区内移动台的发射功率,从而增加系统容量.作者在通用仿真平台OPNET上建立时分双工CDMA系统物理信道模型,并在系统中应用中继技术,通过仿真分析比较了系统的性能.     

无线协作中继技术综述

无线协作中继技术具有低成本、扩大覆盖范围的作用,可以有效提高通信系统的可靠性和传输速率。对无线协作中继技术进行综述,讨论协作中继的基本协议和协作中继的选择方案,并且进行比较分析和仿真验证。     

无线协作中继技术综述

无线协作中继技术具有低成本、扩大覆盖范围的作用,可以有效提高通信系统的可靠性和传输速率。本文对无线协作中继技术进行综述,主要讨论了协作中继的基本协议,并对协作中继的选择方案进行了比较分析。     

协同中继传输处理技术研究

协同通信技术能够有效抵抗信道衰落、提高系统容量、扩大系统覆盖范围,广泛应用于蜂窝移动网络,无线传感器网络,及车到车通信等。特别是协同中继传输协议,已经成为近年来研究的热点。虽说目前有关协同中继传输协议的研究已经取得了一些成果,但是很多中继传输协议都有各自的局限性及不足之处。因此,对协同中继传输处理技术进行更深一步的探讨和研究是十分必要的。文章对现有的各种中继传输协议进行归纳总结,并指出其优缺点以及中继传输协议的研究方向。     

无线移动通信系统关键技术研究

无线移动通信系统已经得到了普及应用,如何提高无线信号传输的效率、提高天线接收效率等问题,将是未来一段时间内,人们研究的主要问题.本文在无线移动通信系统发展的基础上,结合我国自身的实际情况,从信号的处理和传输、多入多出技术、智能天线技术和传输协议等方面,对未来无线移动通信系统的关键技术,进行了深入的分析,希望能给实际无线移动通信系统的研究,提供一定的参考.     

下一代移动通信系统中的中继技术

作为下一代移动通信系统的候选关键技术之一,无线多跳中继技术能以成本有效的方式提供覆盖扩展及吞吐量和容量的增强。文章首先引入中继网络的模型,介绍了多跳中继的应用场景,并阐述了WiMAX系统中的接口和协议体系;随后讨论了多跳中继系统中所特有的路径管理和无线资源管理等技术。     

无线路由器中继功能实战

现在许多家庭都有多个无线终端,笔记本,手机,平板等,为了上网的需求,就需要购置无线路由器,但有时受线路,位置的影响,会发现在卧室或其它房间信号不好,网络上不去,办法就是再购置一台路由器放在信号弱的房间,将原来无线信号接收过来,再放大进行中继,能很好解决这种问题。     

Nested cooperative encoding protocol for wireless networks with high energy efficiency

Recently, distributed space-time code designs with high cooperative diversity for wireless communication networks, such as ad hoc and sensor networks, have received much attention. Amplify forward and decoding forward are widely used protocols for the cooperative diversity in the wireless communication networks. In both protocols, the information received by relay terminals are "forwarded" to destination or next relay terminals. Since the signals transmitted by relay terminals and those transmitted from the source terminal are correlated, there is information redundancy. To improve the energy efficiency of cooperative networks, we propose an encoding protocol, which is referred to as a nested cooperative encoding protocol. In our proposed protocol, the received signal at each relay terminal is divided into several sub-signals with the nest lattice structure of source information. Each of the sub-signals contains only a partial information with a smaller size of constellation compared to the original information sent by the source terminal. Do a new encoding or modulation by using these sub-signals before transmitting at relay terminals. It is shown that the proposed new protocols can achieve both high cooperative diversity and high energy efficiency.     

无线移动机器人及运动监测系统的设计

介绍了一种无线两轮驱动机器人小车和软硬件实现方法,计算机通过串口无线控制机器人小车和接收机器小车反馈回来的运动状态信息。在对几种近距无线通信协议进行分析和比较的基础上,选用Zigbee协议栈技术作为基本的通信协议,并基于该协议实现遥控机器人小车和监测小车的运动状态,通过监测机器人的运动状态来提高控制的准确度。CC2430无线单片机负责无线通信和组网,MSP430单片机作为主控制芯片,MSP430通过产生两路PWM波来控制两路直流电机,实现机器人根据计算机发出的各种命令执行不同的动作。该机器人已用于危险环境监测研究当中。     

基于LabVIEW的光伏发电远程电能监控系统设计

提出了一种直流母线式的有蓄电池有逆流发电系统结构。使用智能单相电能表作为电能信号的采集终端,将采集所得的各种电能信号采用MODBUS-RTU通讯协议通过485总线传输至485/USB转换器,再由转换器送至上位机进行读取。上位机的各种控制指令通过XBee无线传输模块发送给现场单片机控制模块,由单片机实现对现场设备的控制。通过LabVIEW开发平台编写可视化较强的上位机界面,并利用WEB发布技术将前面板发布至网络上进而实现运程监控。通过测试及分析,结果显示整个系统运行良好、稳定、实时性强。     

Selection Cooperation in Heterogeneous Cooperative Networks

Selection cooperation is an attractive cooperative strategy for wireless networks due to its simplicity and efficiency. In this paper, we consider a heterogeneous cooperative network consisting of different kinds of nodes with low-cost radios where the activities of one kind of nodes are triggered by the other kinds of nodes. This is a common scenario for many networks, such as wireless sensor networks. By exploiting the transmission relationship between heterogeneous nodes, we propose a selection cooperation protocol where inducing nodes can cooperate with the following nodes after their own transmissions for improving the communication reliability of the latter nodes. Through performance analysis, we show an interesting feature that the diversity-multiplexing tradeoff of the proposed protocol does not rely on the best relay selection method and the protocol always achieves the full diversity gain. We further develop an energy-efficient best relay selection method based on power control where the power consumption is minimized without decreasing the full diversity order. Simulation results demonstrate the good performance of the protocol and the remarkable energy reduction of the proposed best relay selection method.     

轻量级WSN分层协议栈的设计与实现

传统无线网络协议栈存在硬件兼容性弱、内存和CPU占用率高、函数接口复杂等问题,采用此类协议栈将提高项目开发的软硬件成本。设计一种轻量级分层协议栈,通过协议栈架构的分层设计、底层的开放式设计、函数的可重入设计等,使其具有低系统资源占用率、高可移植性和多网卡协同工作的特点。采用IAR EW8051,KEIL MDK,STM32CUBE等作为软件平台,进行协议栈程序的开发与测试。测试结果表明,该协议栈代码量小,可应用于CC1100,CC2500,SI4463, SX1278等无线芯片,且能有效应对复杂环境下的信号干扰,提升点对多通信效果,有较高的实用价值。     

空中异构战术网络IP通信架构及协议开销分析

空中异构战术无线网络由多种不同类型的无线数据链网络构成，IP通信技术可有效解决空中平台异构无线网络的互联互通问题。给出了空中异构战术无线网络模型，并根据不同类型的无线数据链网络特点，分析了端到端通信协议栈关系以及不同无线数据链网络间协议转换与适配方式。探讨了网络静态和动态IP地址分配方法以及网络的路由架构与寻址方式，提出了不同无线数据链网络间IP报文传输的打包方式。对传输的开销性能仿真对比分析表明，基于通用成帧协议的打包方式的协议开销性能较优。     

Secure communication via an energy-harvesting untrusted relay in the presence of an eavesdropper

This article studies a secure communication of a simultaneous wireless information and power transfer system in which an energy-constrained untrusted relay, which harvests energy from the wireless signals, helps the communication between the source and destination and is able to decode the source’s confidential signal. Additionally, the source’s confidential signal is also overheard by a passive eavesdropper. To create positive secrecy capacity, a destination-assisted jamming signal that is completely cancelled at the destination is adopted. Moreover, the jamming signal is also exploited as an additional energy source. To evaluate the secrecy performance, analytical expressions for the secrecy outage probability (SOP) and the average secrecy capacity are derived. Moreover, a high-power approximation for the SOP is presented. The accuracy of the analytical results is verified by Monte Carlo simulations. Numerical results provide valuable insights into the effect of various system parameters, such as the energy-harvesting efficiency, secrecy rate threshold, power-splitting ratio, transmit powers, and locations of the relay and eavesdropper, on the secrecy performance.     

Efficient Beamforming by SLNR Maximization for Dual-Hop Relay Assisted MIMO Network

Relay beamforming is a key signal processing technique to mitigate interference in single and multiuser multiple input and multiple output (MIMO) wireless communication networks. In MIMO relay networks interference cancellation is an essential task of the study to get optimal network capacity. In this paper, the problem of interference resulted from leakage signal from desired signal for intended antenna, which causing interference to other antennas of the same user with multiple antennas is tackled. The criterion of signal to leakage plus noise ratio (SLNR) maximization is considered to design a vector by vector relay downlink precoding based on Fukunaga Koontz transform. This can control the interference among multiple antennas and maximize SLNR. However, matched filter beamforming is utilized at the relay receiving side that can increase output signal to noise ratio at the relay node. The channel state information of both the channel between source to relay and relay to destination is assumed at the relay node. The effectiveness of the proposed technique is studied and compared with conventional relay precoding techniques. Simulation is carried out in MATLAB environment using ideal channel conditions. This study demonstrates that, the proposed scheme for relay assisted MIMO networks can improve overall system performance in terms of ergodic capacity.     

移动中继通信技术综述

随着无线通信的发展,以中继为代表的协作通信技术被认为是未来无线通信系统中的关键技术之一。利用中继可以以较小的代价扩展小区覆盖范围和增加系统容量。目前,固定中继的研究已日趋成熟,移动中继正成为一个新的研究热点。由于移动中继本身的特性,它在带来诸多好处的同时也面临一些挑战。文中阐述了移动中继的研究现状,介绍了移动中继的应用场景,对其关键技术进行了综述与展望。     

Adaptive linearly constrained minimum variance beamforming for multiuser cooperative relaying using the kalman filter

In this paper, we consider a wireless communication scenario with multiple source-destination pairs communicating through several cooperative amplify-and-forward relay terminals. The relays are equipped with multiple antennas that receive the source signals and transmit them to the destination nodes. We develop two iterative relay beamforming algorithms that can be applied in real-time. In both algorithms, the relay beamforming matrices are jointly designed by minimizing the received power at all the destination nodes while preserving the desired signal at each destination. The first algorithm requires the existence of a local processing center that computes the beamforming coefficients of all the relays. In the second algorithm, each relay can compute its beamforming coefficients locally with the help of some common information that is broadcasted from the other relays. This is achieved at the expense of enforcing the desired signal preservation constraints non-cooperatively. We provide two extensions of the proposed algorithms that allow the relays to control their transmission power and to modify the quality of service provided to different sources. Simulation results are presented validating the ability of the proposed algorithms to perform their beamforming tasks efficiently and to track rapid changes in the operating environment.