认知无线电研究进展及应用前景

 认知无线电被认为是解决频谱资源紧缺、提高频谱利用率的有效途径,成为现代无线通信领域的研究热点之一。在广泛调研的基础上,从频谱政策演进、网络与标准发展等方面综述了近10年来认知无线电的研究进展,展望了认知无线电在智能电网、宽带蜂窝网、公共安全网和医疗体域网等新兴无线通信业务方面的应用前景,并提出认知无线电领域未来的研究方向。     

对绿色无线移动通信技术的研究和思考

论述了协作通信分布式天线系统,能有效降低系统的发射功率,是一种可靠的绿色移动网络的解决方案;提出了绿色无线通信的系统设计考虑,特别提出对业务内容的软实时业务传输的新设计,能明显降低成本节省资源和功耗;论述了利用基于认知技术的可重配置无线网络能明显降低能源开销;论述了未来无线通信由追求更高、更快的传输能力向追求更省、更好的能源效率的转变;提出小区网络设计的环保效率函数,用来评价和设计环保下的小区网络.这些论述反映了对绿色无线通信技术研究的成果和思考.     

传感器定位节点的应用设计与实施

将定位功能融入到节点中,设计并实施了一种具有定位功能的传感器网络节点.该节点具有内置定位引擎,通过获取节点间的接收信号强度,转换成相应的距离信息.当获取3个以上已知节点坐标后,采用极大似然估计法给节点定位.实验结果表明,该节点定位精度3 m,可以满足一般传感器网络应用的需要.     

Ad hoc网络路由问题的研究

随着无线网络的广泛应用,设计一种有效安全的路由协议是目前亟待研究的重要课题。Ad hoc的应用产生了传统网络所未遇到过的安全问题。研究了目前常见的标准路由算法,分析了发生在路由层的攻击手段,阐述了几种路由安全机制。     

基于GSM网络的远程监控系统设计与实现

利用GSM网络作为无线智能监控系统的信息传输平台是一种很有效的方法,其原理简单,安全保密性高,又不需要组建专用网络和维护网络,加上GSM网络覆盖面广,因此与传统的监控系统相比有着其独特的优势.作者成功实现了基于GSM网络的智能监控模块的设计.该模块硬件是由两块PCB板构成,一块是监控主板,主要由CPU及外围部分、LCD部分、语音和外围电路构成,主要完成模拟量和数字量的监测,并及时在LCD上显示出监测状态,并且在需要报警的时候播放预先存储在语音芯片的语音信息;另一块是无线MODEM,由GSM引擎TC35i及其外围电路构成,主要完成短信息的发送和接收,以及在紧急情况下的智能语音报警功能.该系统可广泛应用于智能家居监控、无人值守的设备维护以及现代自动化生产线的监控等领域,具有比较广阔的市场前景.     

Reconfiguration decision making in cognitive wireless network

Facing the challenges of dynamic adaptation capabilities in the time-varying environment of cognitive wireless networks (CWNs), we introduce reconfiguration capabilities that flexibly and dynamically adapt to changing wireless environments and service requirements. As an essential characteristic of CWNs, the cognitive reconfiguration can meet user requirements, realize interoperability between heterogeneous networks, make full use of radio resources and adapt to time-varying environments to achieve end-to-end requirements. However, the reconfiguration implementation is still challenging due to the need for complex environment cognition, multi-objective optimization, autonomic decision-making and end-to-end requirement extraction. As an intelligent technology for solving complex issues, we apply adaptive neuro-fuzzy inference system (ANFIS) techniques in this paper to address these challenges in cognitive reconfiguration for self-learning and optimal decision making based on multi-domain cognition results. Moreover, this paper designs a generic ANFIS cognitive reconfiguration system including three functional entities, which are the context management module, multi-domain database and ANFIS optimization module. Finally, numerous results prove the effective performance improvements of the ANFIS based reconfiguration solution in CWN for global end-to-end goals.     

无线网络中的资源分配和调度算法综述(英文)

无线网络的资源分配对提高系统性能具有重要意义。在分析无线网络的资源调度策略与传统有线网络相比的独特之处的基础上,重点针对无线局域网、基于TDMA的蜂窝移动通信网络及基于CDMA的蜂窝移动通信网络的资源分配和调度算法进行综合分析,指出了这些算法的特点。该综述可供无线网络相关研究和设计参考。     

无线网络中的资源分配和调度算法综述

无线网络的资源分配对提高系统性能具有重要意义.在分析无线网络的资源调度策略与传统有线网络相比的独特之处的基础上,重点针对无线局域网、基于TDMA的蜂窝移动通信网络及基于CDMA的蜂窝移动通信网络的资源分配和调度算法进行综合分析,指出了这些算法的特点.该综述可供无线网络相关研究和设计参考.     

Exploration of energy conservation MAC protocol of WSNs for ubiquitous environment

According to analyze the facade phenomenon of wire-less sensor networks（WSNs）,this paper proposes a feasible method to state clearly and improve the power control efficiency of wire-less sensor networks（WSNs）. One of the crucial problems for WSNs is the design of medium access control （MAC） protocol. Our method want to adjust the activities of the MAC protocols control to achieve the enery conservation when the wireless communication module of sensor nodes is running, which is the major consumer of energy consumed by sensors energy. The energy efficiency of MAC protocol makes a strong impact on the network performance. To some extent,our research work describes and analyze the sources of energy consumption in MAC layer and simultaneously present an optimal method for the design of MAC protocol. Then we discusses some factors impacting on the performance of MAC protocol and metrics of performance evaluation. Eventually, the coming research direction is summarized.     

一种异构可重构的认知无线电平台及设计方法

未来无线通信频带越来越紧张,认知无线电可感知频谱,使认知用户和认证用户可以无干扰地共享频谱,并成为一种提高频谱利用率的重要方法。提出了一种基于SoC(System on Chip)的异构可重构认知无线电平台及设计方法,该方法满足认知无线电感知频谱、适应无线信道时变的要求,并能高效、低能耗地实现认知无线电的动态配置。     

无线传感器网络操作系统中抢占式任务调度策略

提出了一种基于优先级的抢占式无线传感器网络操作系统调度策略IS-EDF,并在TinyOS上进行实现.提出的调度策略通过动态调整执行任务的优先级,可以有效地保证重要任务的实时性,改善无线传感器节点在任务负载较重情况下的系统响应性能;在节点处于轻负载或者空闲情况下,通过将节点带入睡眠状态,保证了无线传感器节点的节能.通过实验和仿真可以得出,提出的任务调度策略,在总能耗增加很少的代价下,可以有效地提高系统在运行负载较重情况下的系统响应性能.     

认知异构无线网络中频谱切换建模与分析

在具有频谱认知功能的异构无线网络中,针对传统频谱切换算法未考虑次用户业务的多样性,且空闲信道不足造成次用户服务时延大的问题,提出基于次用户分级的频谱切换策略。与以往单一的认知无线电网络不同,该策略融合利用免授权频谱的开放式无线网络和机会式利用授权频谱的认知无线电网络,提出了认知异构无线网络场景。根据次用户的业务类型对其进行优先级划分,并在此基础上设计数据分割因子优化策略。进一步采用混合式抢占优先权(preemptive resume priority /non-preemptive resume priority,PRP/NPRP) M/G/1排队模型,分别对主用户网络和开放式无线网络中的频谱切换过程进行建模,提出一个最小化时延的动态自适应频谱切换策略。实验仿真了不同参数对次用户时延的影响,结果表明,该策略较传统的频谱切换策略明显提升了次用户的时延性能。     

异构无线传感器网络跨层协议研究现状

信息技术的不断发展使泛在式异构一体化综合网络应运而生,包含了节点异构性、链路异构性和网络协议异构性等特点的异构无线传感器网络(HWSN)已在众多领域得到大量应用.为进一步提高HWSN网络整体性能,对HWSN进行跨层设计已成为当前研究的一个重要途径.但目前关于HWSN跨层协议的研究仍处于起步阶段,且实际应用于HWSN的跨层协议尚不成熟.通过分析HWSN跨层设计的目的和方法,从应用层、传输层、网络层、MAC层、物理层5个层次比较了当前HWSN跨层协议并对相关协议进行研究,旨在探讨HWSN跨层设计的发展方向,为相关研究工作提供一定的参考和借鉴.     

Cognitive information metrics for cognitive wireless networks

Considering the dynamic changes and uncer- tainty features of the radio environment in cognitive wireless networks （CWNs）, the environment cognition ability is critical for the performance evaluation of CWNs design and optimization. However, there are no effective metrics to evaluate the ability and gain of information cognition in CWNs from an information theory perspec- tive. Therefore, the novel cognitive information concept is proposed and defined as a metric to evaluate the uncer- tainty of both the internal and external environments of one system that can be removed by other systems or nodes using cognitive radio techniques. As an intelligent wireless communication system that is aware of its surrounding radio, network, and user multi-domains environment, the more cognitive information it achieves, the higher level cognitive capability it is. In this paper, we define and analyze the mathematical features of cognitive informa- tion. Results reveal that the increase of cognitive infor- mation can improve the spectrum efficiency and reduce the interference probability simultaneously in CWNs. Thus cognitive information can be regarded as a metric for CWNs optimization. Finally, we apply the theory of cog- nitive information in the parameters optimization in energy detection and cooperative spectrum sensing.     

Intelligent and efficient development of wireless networks: A review of cognitive radio networks

Facing the challenges on how to improve spectrum efficiency and how to realize heterogeneous network convergence in future wireless networks, a cognitive radio network (CRN) is proposed as one of the solutions. This has become a major research topic in recent years and it is timely to give an overview of the development of CRN and to summarize key issues and technologies. The fundamental concepts of CRN, including the cognitive cycle model, the network architecture, and the cognitive ability and intelligent decision functions, are introduced in detail based on recent advances. Key issues for each topic, followed with recent research on theory and method, are then classified and the industrialization developments of CRN testbeds based on TD-LTE cellular system and standards are briefly presented. Finally, conclusions are reached on the perspectives and directions of future development.     

Dynamic overlapped spectrum allocation based on potential game in cognitive radio networks

In order to make full use of wireless spectrum resources,the behavior of cognitive radio （CR）for dynamic spectrum allocation is analyzed based on the game theoretic framework.The traditional spectrum allocation schemes consider the spectrum allocation among independent frequency bands only,without taking into account mutually overlapped frequency bands.For this reason,an optimal allocation etiquette is defined to promote the cross characteristic of the frequency bands in a dynamic spectrum allocation model.New interference operator and interference temperature constraints are introduced in order to realize calculation of the interference,and the corresponding spectrum allocation scenario can be further formulated as a potential game.Based on the characteristic of dynamic selection using the game theory and the interference avoidance rule of interference temperature,the robustness of CR networks is increased and the scenario is more suitable for the dynamic changing of actual wireless communication and energy saving communication systems.Simulation results show that the signal to interference and noise ratio （SINR） level can be significantly improved through the optimal allocation of any available spectrum.The utilization rate of spectrum and throughput of overall CR networks are increased by fully utilizing the spectrum resources in the dynamic spectrum allocation model.     

无线Mesh网络QoS保障技术综述

首先,简要回顾了无线Mesh网络的基本概况,分析了在无线Mesh网络中提供QoS保障的必要性和重要意义.然后,系统地介绍了无线Mesh网络的物理层、MAC层和路由层QoS保障技术以及跨层QOS设计技术的国内外研究现状,对其进行了细致而科学的分类.最后,给出了它们的研究难点和研究方向.     

WSN的定位技术在污染源监测系统中的应用

本文首先阐述了污染源监测系统中各类节点的硬件设计。介绍了CC2431芯片,分析了基于RSSI测距技术的定位机制,并引入了一种优化的测距算法。该算法通过对测距模型的校正,提高了定位引擎的定位精度,因此缩短了对污染源的巡查时间,提高了处理事故的效率。     

基于MSP430的船舶机舱无线监测系统设计

以机舱设备温度监测为例,采用MSP430F149为主芯片设计一种由多个传感器节点模块、中心节点模块和机舱监测计算机构成的无线监测系统.通过微处理器技术、无线通信技术和传感器技术的融合,自主实现温度数据的采集、融合和传输,节省了布线开支,提高了机舱监测系统的可靠性和灵活性.     

无线传感器网络地址重构硅知识产权核

在基于Zigbee协议的无线传感器网络中采用少数字节固定表示节点地址,由于地址不够分配,就会出现地址缺乏．为实现无线传感器网络节点中地址的灵活调整,适应片上系统集成化的需求,解决无线传感器网络中地址不够分配的问题,提出了无线传感器网络地址重构硅知识产权（IP）核．描述了无线传感器网络地址重构IP核的数学求解模型．应用模块化分割技术采用硬件描述语言,在电子设计自动化（EDA）中综合实现了地址重构IP核．仿真结果表明,所完成的地址重构IP核可以满足无线传感器网络节点地址的灵活预置调整．为无线传感器网络节点单芯片系统的地址重构集成化提供了意义．