认知无线电的频谱感知算法研究

频谱感知技术、频谱共享技术、频谱管理技术是当前认知无线电的三大核心技术,而频谱感知技术是实现后续的频谱共享和频谱管理的前提。因此主要对当前认知无线电频谱感知技术的基础理论、算法模型以及频谱感知的具体算法做了详尽的分类,并利用Matlab仿真平台对主要的频谱感知算法进行了仿真,并根据仿真结果,比较了各个算法的性能优劣性,可为认知无线电用户的算法选择提供参考,同时也为认知无线电后续的频谱共享和频谱管理工作奠定一定基础。     

基于循环平稳特征的频谱感知算法概述

传统的静态频谱资源分配分配政策导致频谱利用率低下,为解决这一问题,人们提出利用认知无线电技术实现动态频谱接入.频谱感知是认知无线电的关键技术,循环平稳特征检测算法是3种常见频谱检测算法之一,但是该算法存在各种不足.首先简要介绍认知无线电的背景和概念,然后详细介绍了循环平稳特征检测算法,以及目前提出的各种基于循环平稳特征检测的增强算法,分析了各自的原理及其优缺点.     

认知无线电合作频谱感知算法研究

频谱感知是实现认知无线电功能的前提条件,也是认知无线电领域的一个研究热点。近年来人们提出了很多频谱感知的方法,尤其是合作频谱感知算法日益受到人们的关注。综述了合作频谱感知技术的最新研究进展,从简单的线性信息融合算法到复杂的非线性感知算法,以及多天线合作感知等算法,通过仿真比较各种方法的检测性能,并展望未来频谱感知所面临的挑战和发展趋势。     

基于信任度与信噪比的认知无线电协同频谱检测

无线网络中存在信噪比较高的恶意认知用户的情况,为了有效利用可靠的认知无线电(CR)技术用户的本地感知结果,提出了一种基于信任度的信噪比比较协同频谱感知算法,可有效剔除认知网络中存在的信噪比较高的恶意认知用户。仿真实验表明,在存在恶意认知用户的认知无线电网络中,该算法检测性能优于传统的或准则(OR)数据融合的协同频谱感知算法以及基于信噪比比较协同频谱感知算法。     

认知网络中的协作频谱感知技术研究

认知无线电技术通过感知频谱后进行动态频谱资源分配,极大地提高了频谱利用效率。频谱感知是实现认知无线电技术的前提和基础,文中针对频谱感知技术中单节点检测的局限性对能够改善频谱感知能力的协作感知技术进行了分析及讨论,重点分析了基于能量检测法的协作感知中的各种数据融合算法,并在此基础上提出了目前协作感知中存在的问题及未来的研究方向。     

一种新的联合频谱能量检测方法

认知无线电技术被认为是解决未来频谱资源紧张的一种有效方法。而频谱感知技术是认知无线电中的一种关键技术,只有通过有效的频谱感知才能合理利用空间的频谱空洞。在传统的时域能量检测的基础上给出了一种结合时域与频域的新的频谱感知方法。该方法充分利用了时域与频域能量检测的优点,理论分析与仿真结果表明,该方法具有感知准确率高,功耗小的优点。适合于未来认知无线电中的应用。     

频谱空穴检测及其仿真

感知无线电接收机为了感知其周围的无线电环境,首要的工作就是对其周围存在的信号进行检测。本文针对感知无线电系统中最为关键的频谱空穴检测技术进行了研究。通过对3种信号检测技术的比较,选择循环平稳特征检测法作为感知无线频谱的方法并对该方法进行了仿真。此外．对控制实体根据频谱感知的结果、从频谱中检测出频谱空穴区域的功能、以及感知无线电接收机与感知无线电发射机进行协调的功能也进行了仿真。     

基于一致优化的分布式宽带合作频谱感知算法

在压缩采样的框架下,提出一种基于一致优化的分布式宽带频谱压缩感知算法。算法思想如下:认知无线电网络中每个认知节点首先根据压缩采样理论获取压缩采样,并恢复本地的频谱信息,然后在一跳范围内交换频谱信息。认知节点将获取的邻居节点频谱信息进行加权平均,此加权平均作为频谱恢复一致优化问题的约束,以此来降低计算开销,加速算法的收敛。优化问题通过最优交替方向乘子法迭代求解来获取整个认知无线电网络的频谱估计。给出了算法的收敛性证明,并进行了仿真实验以验证算法的有效性。     

瑞利信道中自适应双门限频谱感知算法研究

频谱感知是认知无线电中的一项关键技术,能量检测、匹配滤波器检测和周期循环频谱检测是认知无线电中频谱感知技术中传统、经典的算法.基于能量检测的频谱感知算法因实现简单且不需要先验信息而被广泛应用,但低信噪比的情况下检测概率会降低,用户的检测性能不足,从而导致认知用户和主用户之间的冲突碰撞次数增多.针对以上存在的问题,在基于自适应频谱感知的基础上,利用噪声功率估计,提出了一种瑞利信道下的自适应双门限频谱感知算法.仿真结果表明,在低信噪比噪声不确定的情况下,这种算法能够大大提高检测概率,有效降低了认知用户和主用户之间的冲突碰撞次数,从而提高频谱的利用率.     

基于Stackelberg博弈的多任务协作频谱感知算法

随着移动设备的增多,认知无线电技术诞生,而频谱感知是认知无线电技术中的重要一环。本文将群智感知和频谱感知结合,提出了一种基于Stackelberg博弈的多任务协作频谱感知算法。该算法将融合中心(平台)与次用户分别建模为Stackelberg博弈领导者和从属者。在领导者博弈中,平台给次用户发布最优的报酬值以获得最佳的效用;在从属者博弈中,本文着重考虑了剩余能量对次用户的影响,次用户在平台给的报酬下改变感知时间以获得最优的效用。仿真结果表明,该算法可以提高融合中心对频谱的检测概率。      

Cognitive radio network with coordinated multipoint joint transmission

Cognitive radio (CR) is considered to be a promising technology for future wireless networks to make opportunistic utilization of the unused or underused licensed spectrum. Meanwhile, coordinated multipoint joint transmission (CoMP JT) is another promising technique to improve the performance of cellular networks. In this paper, we propose a CR system with CoMP JT technique. We develop an analytical model of the received signal‐to‐noise ratio at a CR to determine the energy detection threshold and the minimum number of required samples for energy detection–based spectrum sensing in a CR network (CRN) with CoMP JT technique. The performance of energy detection–based spectrum sensing under the developed analytical model is evaluated by simulation and found to be reliable. We formulate an optimization problem for a CRN with CoMP JT technique to configure the channel allocation and user scheduling for maximizing the minimum throughput of the users. The problem is found to be a complex mixed integer linear programming. We solve the problem using an optimization tool for several CRN instances by limiting the number of slots in frames. Further, we propose a heuristic‐based simple channel allocation and user scheduling algorithm to maximize the minimum throughput of the users in CRNs with CoMP JT technique. The proposed algorithm is evaluated via simulation and found to be very efficient.     

Cross‐layer optimization for full‐duplex cognitive radio network with cooperative spectrum sensing

In this paper, the cross‐layer optimal design of multihop ad hoc network employing full‐duplex cognitive radios (CRs) is investigated. Firstly, the analytical expressions of cooperative spectrum sensing performance for multihop CR networks over composite fading channels are derived. Then, the opportunistic throughput and transmit power of CRs are presented based on the derivation of false alarm and missed detection probability. Finally, a multiobjective optimization model is proposed to maximize the opportunistic throughputs and minimize the transmitting power. Simulation results indicate that Pareto optimal solution of sensing duration, decision threshold, and transmit power can be achieved by cross‐layer multiobjective optimization, it can balance the conflicts between different objective functions and reap the acceptable outcomes for multihop CR network.     

基于非参量累积和的合作频谱感知

针对认知无线电网络中频谱感知的检测时延降低问题,提出了基于非参量累积和的合作频谱感知算法。本地认知用户预处理频谱观测数据,获得观测数据相对于信念值的正向漂移和负向漂移。为了缩短检测延迟,认知用户只将数据的正向漂移同步传输至融合中心。融合中心融合正向漂移得到判决信息,采用非参量累积和算法依时间序列顺序累加判决信息,判断主用户是否正在使用授权频段。为了解决不传输负向漂移引起的虚警问题,改进算法提出融合中心可以保留首次判决,经过等待时间间隔后再作出最终判决。相对于传统的软融合算法,改进融合规则的合作频谱感知算法具有较低的检测延迟。     

Optimization algorithm of periodical cooperative spectrum sensing in cognitive radio

To decrease the interference to the primary user (PU) and improve the detected performance of cognitive radio (CR), a single‐band sensing scheme wherein the CR periodically senses the PU by cooperative spectrum sensing is proposed in this paper. In this scheme, CR first senses and then transmits during each period, and after the presence of the PU is detected, CR has to vacate to search another idle channel. The joint optimization algorithm based on the double optimization is proposed to optimize the periodical cooperative spectrum sensing scheme. The maximal throughput and minimal search time can be respectively obtained through the joint optimization of the local sensing time and the number of the cooperative CRs. We also extend this scheme to the periodical wideband cooperative spectrum sensing, and the joint optimization algorithm of the numbers of the sensing time slots and cooperative CRs is also proposed to obtain the maximal throughput of CR. The simulation shows that the proposed algorithm has lower computational quantity, and compared with the previous algorithms, when SNR = 5 dB, the throughput and search time of the proposed algorithm can respectively improve 0.3 kB and decrease 0.4 s. The simulation also indicates that the wideband cooperative spectrum sensing can achieve higher throughput than the single‐band cooperative spectrum sensing. Copyright © 2012 John Wiley & Sons, Ltd.     

Detection efficiency of cooperative spectrum sensing in cognitive radio network

Sensing the spectrum in a reliable and efficient manner is crucial to cognitive radio. To combat the channel fading suffered by the single radio, cooperative spectrum sensing is employed, to associate the detection of multiple radios. In this article, the optimization problem of detection efficiency under the constraint of detection probability is investigated, and an algorithm to evaluate the required radio number and sensing time for maximal detection efficiency is presented. To show the effect of cooperation on the detection efficiency, the proposed algorithm is applied to cooperative sensing using the spectral correlation detector under the Rayleigh flat fading channel.     

认知无线电网络链路层关键技术的研究进展

构建认知无线电网络是解决频谱资源日趋紧张问题的根本途径.为实现无干扰的伺机频谱共享,认知无线电网络的链路层不仅需要提供传统的数据传输服务,还必须支持一套与频谱非均匀特性相适应的新功能.对这些新功能所需的关键技术进行了归纳,分别从协作感知、感知机制优化、动态频谱接入、动态频谱分配、跨层设计及安全机制等6个方面进行了探讨,重点对这些关键技术的最新研究进展进行了总结和分析,并讨论了下一步的主要研究方向.     

传感能力约束下的认知无线网络的多波段光谱感应优化

This paper addresses the problem of joint optimization of subchannel selection and spectrum sensing time for multiband cognitive radio networks under the sensing capability constrains. In particular, we construct a multiband spectrum sensing framework, and derive the probabilities of detection and false alarm taking the different subchannel gain into account. Furthermore, we formulate the multiband sensing as a two-parameter optimization problem under the sensing capability constrains and guaranteeing the QoS of the secondary user. Moreover, we develop a semi-analytical optimization scheme to achieve the optimal solution.     

Optimization of 2‐stage cooperative spectrum for cognitive radio networks using multi‐antenna energy detectors

Cooperative spectrum sensing, a kind of spectrum sensing scheme in cognitive radio (CR), uses multiple CR relays. To increase performance, this study uses multi‐antenna CR relays and beam‐forming reception. The required bandwidth for reporting channels in cooperative spectrum sensing is crucial. Two‐stage cooperative spectrum sensing is proposed to increase performance without increasing the required bandwidth. The cooperative spectrum sensing is also optimized to allow the CR networks to facilitate the best decision‐making. This study determines the detection performance when beam‐forming reception is used. Numerical simulations are used to validate the effectiveness of the method. It is shown that beam‐forming reception outperforms square‐law combining (SLC) for low SNR values. This study proposes a 2‐stage cooperative spectrum sensing method, which uses multi‐antenna CR relays and beam‐forming reception. The cooperative spectrum sensing is also optimized to allow the CR networks to facilitate the best decision‐making. Numerical simulations are used to validate the effectiveness of the method.     

一种新的认知无线电频谱感知方法

认知无线电是一种用于提高无线电通信频谱利用率的新的智能技术。首先简述了认知无线电的背景和概念,然后针对认知无线电频谱感知的能力,对比分析了现有的三种频谱检测方法：匹配滤波器法、能量检查法和循环平稳特征检测法,在对其进行研究的基础上,提出一种将能量检测法和循环平稳特征检测法相结合的双门限检测法,通过仿真验证了该方法的有效性和优越性。     

Optimal energy-efficiency capacity and sensing tradeoff for hybrid spectrum sharing in CRN

This paper investigates the tradeoff between energy-efficiency capacity and spectrum sensing under hybrid spectrum sharing model,where the spectrum sharing method is based on sensing results of seconda...