认知无线电网络路由及频谱分配联合策略研究

认知无线电网络中的节点可以自主切换通信频率,从而对拓扑和路由产生影响。该文针对多跳认知无线电网络的场景提出了一种路由与频谱分配的联合策略,在按需路由的过程中完成频谱分配任务。实验结果表明,在多数据流并存的认知无线电网络中,该策略较其它路由方法具有更好的适应性和更低的累积时延。     

基于OFDM的协同认知网络跨层资源调度

协同通信与认知无线电是未来移动通信的重要技术。针对基于OFDM的无线协同认知网络中的资源分配问题,该文提出了一种有效的跨层资源调度方案。该调度方案在考虑对主用户所受干扰功率进行控制的前提下,以最大化认知用户超帧中总的传输速率为目标,在调度帧中对各传输帧两阶段的子载波进行最佳配对,并为配对子载波分配最优的发送功率。通过分步求解的方法,该调度方案形成的优化问题得到有效解决。仿真结果表明该资源调度方案使得认知用户传输速率有显著提升,方案的可行性与有效性得到了验证。     

认知Mesh网络的动态分层图路由模型及路由策略

该文提出了在认知无线电Mesh网络环境下的动态分层图路由模型,该模型将节点感知范围内的信道可用性用两状态离散时间马尔可夫链建模,建立认知无线电Mesh网络拓扑和连通性的动态模型。基于该模型提出了一种跨层设计的动态接口分配方案。仿真结果表明,动态分层图模型在适应接入频谱的动态变化和描述认知无线电Mesh网络的拓扑结构方面,表现出比静态分层图模型更加优异的性能。     

基于OFDM认知无线电网络的最优路径算法

针对基于正交频分复用的分布式认知无线电网络,在考虑频谱移动特性的同时,为保证认知用户数据传输的可靠性,提出一种最优路径的基于OFDM认知无线电网络路由算法.该算法首先通过建立认知无线电网络的模型计算信道的期望传输时间和信道干扰,结合类似于按需路由的基本流程得到所有可能的路径.最后,根据最小累积期望传输时间和路径平均吞吐量的指标来选择最优路径.仿真的结果表明,OROCR算法可以明显地减少平均端到端时延,大大地提高平均端到端吞吐量.     

一种改进的认知无线网络路由算法

在SEARCH路由协议中,如果当前路由处于前向避免区域,会造成频谱切换,影响网络拓扑,增加端到端延迟和能量消耗。提出基于地理位置和前向反馈的认知路由算法来解决这一问题。通过信息反馈,该算法能可靠地选择最佳下一跳路由;同时提出认知网络路由算法的评估方案。仿真表明,所提路由选择算法可以很好地降低端到端的延迟和能量消耗。     

认知无线电网络路由研究综述

 在对近期认知无线电网络路由研究成果进行研究的基础上,从邻居节点发现、“耳聋”、邻居节点消失、路由发现和跨层设计等5个方面,对认知无线电网络路由研究面临的重要挑战进行了分析;从研究方法的角度,对路由研究中对公共控制信道的依赖、路径延时,以及需要考虑的技术指标进行了讨论。最后,从介质、信道、节点和网络等4个方面,对路由研究场景设计进行了归纳总结;并从路由优化方案和路由拓扑算法协议两个方面,对主要研究成果进行了分析和讨论。     

An Overview of Scaling Laws in Ad Hoc and Cognitive Radio Networks

Currently, wireless communications are changing along the lines of three main thrusts. The first is the introduction of secondary spectrum licensing (SSL). Regulations on the usage of licensed spectra are being loosened, encouraging unused primary spectrum to be licensed, often in an opportunistic manner, to secondary devices. The second is the introduction of cognitive radios. These wireless devices are able to sense and adapt in a “smart” manner to their wireless environment, making them prime candidates to becoming secondary users in SSL initiatives. Finally, as we approach the communication limits of point-to-point channels, and as wireless devices become cheap and ubiquitous, the focus is shifting from single to multiple communication links, or networks. In this paper, we provide an overview of the recently established theoretical limits, in the form of sum-rates, or throughput, of two main types of networks: ad hoc networks, in which the devices are homogeneous, and cognitive networks, in which a mixture of primary and secondary (or cognitive) devices are present. We summarize and provide intuition on how the throughput of a network scales with its number of nodes n, as n → ∞, under different network and node capability assumptions.

认知无线Ad Hoc网络中的路由尺度和算法设计

在认知无线Ad Hoc网络中,路由问题面临巨大挑战。由于各认知节点可用频谱的时变性、多样性和差异性,传统的路由尺度不再适用于认知无线Ad Hoc网络。本文在自组织认知网络环境下,应用主用户信道的使用模型,同时考虑次用户之间的干扰情况,提出了两类路由尺度和算法,仿真结果表明,这两类路由尺度都能很好地反映端到端性能。     

Energy-efficient Routing of Multimedia Traffic in Frequency-Hop Packet Radio Networks

Conservation of energy is important in a packet radio network, but reliance on energy-efficient routes for all types of traffic leads to large delays and low success probabilities in many situations. We describe and evaluate protocols that select routes according to the service priorities of the traffic. Energy conservation is emphasized for delay-tolerant traffic but sacrificed for delay-intolerant traffic, which gives good performance for both types of traffic.This paper was presented in part at the IEEE Wireless Communications and Networking Conference, Atlanta, March 2004.     

认知无线网络中的频谱切换性能分析

在认知无线网络中,次用户的频谱切换性能不仅和主用户的通信行为关系密切,而且也和次用户本身的频谱感知精度以及频谱切换策略密切相关。该文采用连续时间马尔科夫模型对次用户在理想感知和非理想感知情况下的频谱切换进行建模,进一步分析与比较不同频谱感知精度对频谱切换性能的影响。为了有效降低次用户在频谱切换过程中的强制中断概率,提出基于信道预留机制的频谱切换策略。数值结果表明,次用户对主用户信号的感知精度明显会影响次用户的频谱切换性能,而有效的频谱切换策略则可以以较小的代价获得更好的频谱切换性能。     

跳频分组无线网的路由算法分析

跳频分组无线网抗干扰性好,保密性强,广泛应用于战术通信系统。讨论了几种跳频分组无线网的路由选择算法,着重分析了针对传输多类型分组跳频网的ALR路由算法,并将此路由算法的性能与DAR算法的性能进行了比较,证实了该算法在吞吐量、端-端正确传输率等方面都优于传统的方法。     

基于跨层设计的无线传感器网络节能双向梯度路由算法

针对现有无线传感器网络梯度路由算法在下行路由创建过程和能量更新机制中存在冗余控制开销的问题,该文提出一种采用跨层和功率控制机制,具有节能功能的双向梯度路由算法(Cross-layer Energy-efficient Bidirectional Routing, CEBR)：无需使用专门的控制分组,采用源路由方式以较小开销建立从Sink节点通往传感器节点的下行路由;通过跨层信息共享,定期采集节点剩余能量信息并按需发布;设计使用含跳数和节点剩余能量的合成路由度量标准,减少节点能量和网络带宽消耗的同时均衡节点能耗;结合RSSI(Received Signal Strength Indication)测距实现节点发射功率控制从而在数据及查询分组发送过程中节约节点能量。理论分析表明了CEBR的有效性;仿真结果显示：与现有的典型相关算法相比,CEBR能够在建立双向梯度路由的前提下,至少降低34.5%的归一化控制开销和27.12%的数据分组平均能耗,并使网络生存期延长18.98%以上。     

认知网络中的拥塞规避多径路由算法

链路拥塞导致的数据包传输延时或者数据包丢弃使得网络无法保证业务的Q0S,而目前普遍使用的链路状态路由算法不具有拥塞响应机制.本文针对以上问题,提出了一种能够快速规避拥塞的多径路由算法,该算法通过改进蚂蚁算法,在拥塞发生时采用双向蚂蚁寻路的方法,提高了新路径搜索的速度;使用新的寻路准则使其更满足认知网络的QoS需求.使用...     

一种认知无线Adhoc网络跨层最优频谱共享方案

针对由认知无线电组成的Adhoc网络中的频谱共享提出了一个跨层方案。通过综合考虑认知用户之间的干扰约束和流量需求,特别考虑到用户双向连接以及信道的非均匀性,以BFP（bandwidth—footprint-product）值最小为目,建立了一个二进制整数线性规划（BILP）模型。仿真结果给出了最优的频带分配和路由选择方案。     

多跳认知无线Mesh网络中频谱决策与路由的跨层设计

灵活高效的频谱共享技术能够实现频谱资源的最大化利用,有效地缓解了无线频谱紧缺的现状。在一个与TDMA/FDMA蜂窝网络共存的多跳认知无线Mesh网络环境下,基于覆盖式（Underlay）与机会式（Overlay）相结合的频谱共享机制,提出了一种有效的链路层频谱决策与网络层路由的跨层设计方案。仿真结果表明,该方案比基于最小跳数的随机信道选择算法在网络端到端传输性能上有显著的优势。     

移动Ad Hoc网络的一种跨层功率控制路由协议

移动ad hoe网络中通信终端能量有限,但在许多应用场景,尤其是战场环境下,节点能量消耗较大,因此采用有效的功率控制策略非常重要.利用信道增益的对称性,在AODV协议的基础上提出了一种不依赖于地理位置信息的跨层功率控制路由协议PBAODV,仿真表明该协议在不影响其他网络性能指标的前提下,有效的降低了系统整体功耗.     

Multiple Relay Selection Based on Game Theory in Cooperative Cognitive Radio Networks

Due to the inefficiency of traditional fixed spectrum allocation policies, the paradox of apparent spec-trum scarcity occurs while most of the bands are under-utilized. This has prompted proposals for Dynamic spec-trum sharing (DSS), which explains why Cognitive radio network (CRN) has been widely accepted as a promising approach to settle inefficient usage of scarce available radio spectrum. As a subset of DSS, Dynamic spectrum leasing (DSL) strategy has been proposed based on game idea, where Primary user (PU) has an incentive to allow Cog-nitive users (CUs) to access its licensed spectrum for a fraction of time in exchange for revenue. This paper pro-poses an approach, named multiple relay selection based on Game theory (GTMRS), to optimize the utilities of PU and CUs as a whole, where a pricing-based spectrum leas-ing mechanism is applied. While the parameter price c is jointly determined by PU and CUs, all selected cognitive user's optimal cooperative powers can be satisfied through a non-cooperative game among themselves. Numerical re-sults show that more CUs are involved in the cooperation and both utilities of PU and CUs as a whole are improved, which means the whole system throughput is increased.     

认知网络下TCP协议性能分析

首先在无线环境下的基础上搭建认知平台,当主用户想要占次用户信道时,通过基站的频谱监测,频谱分配,分配次用户到其他空闲信道继续通信.其次,在此平台下分析TCP Reno,TCP Newreno,TCP Sackl和TCP vegas协议的性能,包括拥塞窗口、吞吐量.最后定量分析主用户活跃程度、切换后信道带宽和信道误比特率...     

认知无线电网络中改进的拓扑控制算法

在对认知无线电网络进行信道分配时,网络的拓扑健壮性、对主用户的干扰和认知用户之间的干扰是衡量网络性能优劣的重要指标。文中在假设信道占用时间服从负指数分布的前提下,提出了一个权衡对主用户干扰和认知用户之间干扰的参数,并结合健壮的拓扑控制算法,给出了一种改进的拓扑控制算法。仿真结果表明,ITCA比CRTCA在网络吞吐量上有所增加,冲突率有所降低。     

Neighbor Detection-Based Spectrum Sensing Algorithm in Distributed Cognitive Radio Networks

Security issues of spectrum sensing have drawn a lot of attentions in Cognitive radio networks (CRNs). Malicious users can m islead the network to m ake wrong decision about the states of channels by tampering spectrum sensing data. To defense against Spectrum sens-ing data falsification (SSDF) attack, we propose a neighbor detection-based spectrum sensing algorithm in distributed CRNs, which can detect attackers with the help of neigh-bors during spectrum sensing to improve the accuracy of decision making. The proposed scheme can also guarantee the connectivity of the network. Simulation results illus-trate that the proposed scheme can defense against SSDF attacks effectively and reach the unified information of spectrum sensing data.