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。     

基于动态邻接信任模型的安全路由算法研究

对现有路由节点信任相关问题进行了研究,综合路由节点的状态和行为因素提出了一种路由节点动态邻接信任模型。在此模型基础上提出了一种基于动态邻接信任熵的安全路由算法,并在现有OSPF路由协议中对该路由算法进行了验证。仿真结果表明提出的动态邻接信任模型能够准确地反映路由节点状态改变和恶意攻击,具有良好的动态响应能力,提出的安全路由算法能有效地保证路由节点的行为及状态可信并且具有良好的抗攻击性能。     

Ad Hoc认知无线电网络中基于博弈论的公共信道建立算法

 结合博弈论,论文首先提出一种基于博弈论的适用于认知Ad Hoc网络的公共信道建立算法,但该算法并不保证认知用户总是能够收敛到同一公共信道. 随后,论文提出两种可收敛的改进算法. 仿真结果表明改进算法能够适应不同的网络环境,使用户通过博弈过程最终收敛到同一个空闲信道上,完成公共信道的建立,并能在一定程度上保证信道质量. 最后,论文对算法的收敛性进行了论证.     

分布式认知无线电网络多路径路由协议研究综述

为了深入研究分布式认知无线电网络的多路径路由问题,阐述了分布式认知无线电网络基本特征以及多路径路由设计面临的问题与挑战。分布式认知无线电网络多路径路由采用多路径并行传输,可有效降低传输时延、增加网络吞吐量与传输可靠性、实现网络负载均衡。根据路由优化目标不同,从吞吐量、带宽、干扰、时延、负载均衡和路由发现六方面对近年来多路径路由协议的主要研究成果进行了分类,然后逐类对多路径路由协议进行了分析和讨论,最后分别从分布式认知无线电网络基本特征的适应性与多路径路由协议特征两个方面进行了比较,并展望了分布式认知无线电网络多路径路由协议需进一步研究的方向。     

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。     

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。     

认知无线电中协作中继技术的研究

在无线通信环境中,衰落、多径和节点的移动都会导致通信环境较差,这些因素严重地影响了通信质量。当系统中有协作中继参与时,主用户可以通过共享中继的多根天线来获得增益完成通信从而有效抵抗了无线环境中的不良因素影响。本文建立了一个进行双向通信的主用户需要中继协助才可以完成通信的协作模型。并且定义中继采用放大转发的方式帮助主用户传输数据。本文理论分析了各个节点的中断概率,并通过仿真结果表明,本文提出的中继传输方法不仅使得主用户有效的完成了通信而且还减小了主用户的中断概率。     

认知无线电网络中频谱分配算法

 随着新型无线业务的不断发展,频谱供需矛盾日益明显.认知无线电网络被认为是实现动态频谱共享、缓解频谱供需矛盾的重要途径,近年来相关研究受到了广泛关注.本文对认知无线电网络中的频谱分配研究进展进行了分析.论文首先介绍了认知无线电网络的技术背景,分析了认知无线电网络中频谱分配的关键问题和算法设计目标.在此基础上总结了主流频谱分配模型的设计思想与技术特点,并详细描述了各模型经典分配算法的实现机制.最后,对频谱分配研究趋势进行了展望.     

混合式认知无线电网络路由算法研究

由于认知无线电网络频谱的动态性和差异性,使得传统路由算法不能完全适用.通过分析、总结动态频谱与路由跨层设计研究现状,针对混合式认知无线电网络,以着色图模型为分析模型,为避免交叉节点出现影响网络通信性能,将跳数和链路状态的加权和作为路由选择依据,以最小累积干扰为信道分配指标,提出了一种信道分配和路由选择改进算法(ICARS).仿真结果表明,ICARS算法能获得更好的网络通信质量,为混合式认知无线电网络路由设计提供了一种有效方法.     

基于CSS的认知无线电网络PUEA检测和缓解

针对认知无线电网络中的主用户仿真攻击问题,提出了一种基于能量检测的协作频谱感知方法.首先,假设存在一个智能攻击者,它能知道自己所处环境并可以选择不同的传输策略.然后,调整CSS规则和相关参数为能量探测器确定合适且有效的阈值.最后,利用Neyman-Pearson准则进行能量检测,从而检测出恶意攻击.仿真结果表明,相比传统的基于能量检测的频谱感知方法,该方法可以更好地减轻PUEA在频谱感知中的破坏作用.     

A decision tree cognitive routing scheme for cognitive radio mesh networks

Routing in a cognitive radio network operating in a dynamic environment is a complex decision problem. Diversity in the number of available spectrum bands and their stability, in addition to the secondary users' heterogeneities, affect the consequence of the routing decision. We use a decision theory framework to model the problem of routing under uncertainties involved in a cognitive radio network. A utility function is designed to capture the effect of spectrum measurement, fluctuation of bandwidth availability, and path quality. A node cognitively decides its best candidate among its neighbors by utilizing a decision tree. Each branch of the tree is quantified by the utility function and a posterior probability distribution that predicts the suitability of available neighbors. In decision tree cognitive routing (DTCR), nodes learn their operational environment and adapt their decision‐making accordingly. We compared our scheme with the optimal performance in a highly dynamic environment and local coordination‐based routing and spectrum assignment protocol [1]. Our results show that the DTCR tends to perform near optimum. It easily adapts to environmental dynamics. Copyright © 2013 John Wiley & Sons, Ltd.     

Survey on cluster-based routing protocols for cognitive radio sensor networks

Routing protocols could achieve efficient convergecast transmission of sensed data in cognitive radio sensor network (CRSN),and it is of vital importance for the whole network performance.In particular,cluster-based routing protocols could further lower routing selection complexity and improve scalability.Therefore,an overview of cluster-based routing protocols for CRSN was provided.Firstly,after a brief introduction to the concept and advantages of clustering in CRSN,the major factors concerning clustering algorithm design were pointed out.Secondly,the challenges faced by routing protocol design in CRSN and basic design principles were explored.Thirdly,the previous work of cluster-based routing protocols for CRSN was systematically analyzed and summarized.Finally,issues that require urgent solutions and future research directions were suggested.     

Design of optimum criterion for opportunistic multi-hop routing in cognitive radio networks

The instability of operational channels on cognitive radio networks (CRNs), which is due to the stochastic behavior of primary users (PUs), has increased the complexity of the design of the optimal routing criterion (ORC) in CRNs. The exploitation of available opportunities in CRNs, such as the channel diversity, as well as alternative routes provided by the intermediate nodes belonging to routes (internal backup routes) in the route-cost (or weight) determination, complicate the ORC design. In this paper, to cover the channel diversity, the CRN is modeled as a multigraph in which the weight of each edge is determined according to the behavior of PU senders and the protection of PU receivers. Then, an ORC for CRNs, which is referred to as the stability probability of communication between the source node and the destination node (SPC_SD), is proposed. SPC_SD, which is based on the obtained model, internal backup routes, and probability theory, calculates the precise probability of communication stability between the source and destination. The performance evaluation is conducted using simulations, and the results show that the end-to-end performance improved significantly.     

Scheduling and routing methods for cognitive radio sensor networks in regular topology

Wireless sensor network of regular topology is efficient in area covering and targets locating. However, communications with fixed channels lead to low spectrum efficiency and high probability of conflicts. This paper proposes economical timeslots‐and‐channels allocation methods for scheduling links in square, triangle, and hexagon lattice topologies. Based on these scheduling methods in square lattice, the authors explore routing methods for load balance and delay minimization, respectively, and compare their effects on transmission delay and energy consumption. The OMNet++‐based simulation for square lattice verified the effectiveness of scheduling methods for improving network throughput and made performance comparison among different scheduling methods. It also proved that delay minimization‐oriented routing helps to reduce the energy consumption for node standing by and load balance‐oriented routing helps to reduce the energy consumption for packets transmission. However, there is trade‐off between the reductions of the two types of energy consumptions. The authors further propose the idea of hybrid routing with the two aforementioned routing methods for reducing overall energy consumption and explore the challenges and countermeasures for hybrid routing optimization. Copyright © 2014 John Wiley & Sons, Ltd.     

QoS multicast routing in cognitive radio ad hoc networks

In this paper, we discussed the issues of QoS multicast routing in cognitive radio ad hoc networks. The problem of our concern was: given a cognitive radio ad hoc network and a QoS multicast request, how to find a multicast tree so that the total bandwidth consumption of the multicast is minimized while the QoS requirements are met. We proposed two methods to solve it. One is a two‐phase method. In this method, we first employed a minimal spanning tree‐based algorithm to construct a multicast tree and then proposed a slot assignment algorithm to assign timeslots to the tree links such that the bandwidth consumption of the tree is minimized. The other is an integrated method that considers the multicast routing together with the slot assignment. Extensive simulations were conducted to show the performance of our proposed methods. Copyright © 2011 John Wiley & Sons, Ltd.     

Securing cognitive radio networks

Cognitive radio is a promising technology aiming to improve the utilization of the radio electromagnetic spectrum. A cognitive radio device uses general purpose computer processors that run radio applications software to perform signal processing. The use of this software enables the device to sense and understand its environment and actively change its mode of operation based on its observations. Unfortunately, this solution entails new security challenges. Our objective in this paper is to analyze the security issues of the main recent developments and architectures of cognitive radio networks. We present vulnerabilities inherent to those systems, identify novel types of abuse, classify attacks, and analyze their impact on the operation of cognitive radio‐based systems. Moreover, we discuss and propose security solutions to mitigate such threats. Copyright © 2010 John Wiley & Sons, Ltd.     

认知无线网络中基于主用户行为的联合路由和信道分配算法

针对认知无线网络中主用户行为将导致频谱瞬时变化而影响路由稳定性的问题,提出了一种基于主用户行为的路由和信道联合分配算法。该算法通过采用呼叫模型对主用户行为建模,并根据动态源路由协议的路由寻找机制,在目的节点等待多个路由请求分组后选择受主用户行为影响最小的路由,然后沿着所选定路径的反方向传送路由回复分组并完成信道分配。理论分析证明了算法中的链路平均持续时间期望与主用户活动概率成反比且具有与网络节点数成正比的计算复杂度。仿真结果表明,该算法具有比Gymkhana路由方案更高的分组投递率和更低的平均分组时延。     

Primary user supported routing protocol for cognitive radio ad hoc networks in search of higher throughput

A routing protocol for cognitive radio ad hoc networks (CRAHNs), namely, primary user supported routing (PSR) is demonstrated in this research. Unlike existing routing protocols for CRAHN, where routing of cognitive users (CUs) is accomplished within CUs, in this proposed protocol, some of the primary users (PUs) support CUs to communicate, by forwarding CU packets. This service provided by PU is of voluntary nature. However, such assistance shall be provided by the PUs, only when they are idle, thereby, preserving the principles of cognitive radio networks (CRNs), which indicates that the operation of PU should not be disturbed by the CU activities. The proposed work is compared with cognitive ad hoc on-demand distance vector (CAODV) protocol. The performance parameters considered are routing overhead, rate of loss of packets, and e2e packet delay. PSR outperforms CAODV in all these performance parameters. There has been on average 26.25% improvement in routing overhead, 34.12% decrease in loss, and 27.01% improvement in e2e delivery in the proposed PSR.     

Exploring the impact of social properties on routing in cognitive radio networks

In this paper, we study the social properties, including community, friendship, and individual selfishness of cognitive radio networks and analyze the effect of these social properties on the performance of routing protocols. We first introduce the concept of cooperation willingness considering social relations and individual selfishness. Then, we model the impact of cooperation willingness on the routing performance in cognitive radio networks. After that, we perform extensive simulations to evaluate the accuracy of our model. The simulation results show that our model matched the simulation results well. Finally, our results suggest that community members, friends, and nodes with lower individual selfishness should be selected in the forwarding routes.