感知无线电网络中改进的信道分配算法

针对多信道感知无线电网络中现有协作式频谱感知方法的不足,考虑信道使用特征、检测性能的动态性以及SU选择感知信道时需对PU造成的干扰降至最低等因素,将信道分配问题建模为非线性整数规划问题.为高效地获得该问题的解,通过构建一个完整的二部图并定义合适的权重向量,将该问题转化为凸二部匹配问题,进而提出一种信道分配算法,可在多项式时间内计算出问题的解,包括SU数量、信道数量以及最大权重值.仿真结果表明:随着SU数量的增加,PU的漏检概率和SU的平均可用时间都在下降;本文算法的吞吐量要优于已有的频谱感知算法.

适合于感知无线电网络的动态信道分配和注水功率联合的算法

随着无线通信技术的飞速发展,传统的静态频谱分配机制与频谱实际需求之间的矛盾日益显著,频谱短缺现象日益严重。频谱资源的利用率问题成为未来移动通信发展的一大瓶颈。有效的信道分配机制能够改善无线资源的使用效率。本文将注水功率分配算法和动态信道分配算法相结合,提出一种基于小区的分布式动态信道分配算法。此算法针对感知无线电网络频谱变化的环境和多业务的环境能够提供优越的性能和自适应能力。与其他基于小区的动态信道分配算法相比,此算法考虑用户之间的公平性,显著提高频谱使用效率。

感知无线电网络中改进的恶意用户检测算法

协作式感知可以提升感知精度,但也可能使系统暴露于可能存在的恶意用户的危险之下,甚至会有恶意用户对网络发起拒绝服务攻击.为此给出了一种新的检测算法——恶意用户检测算法(malicious users detection algorithm,MUDA).首先,通过感知服务器对次要用户进行多种感知测试,根据接收到的被测节点的信号强度估计该节点是否为恶意节点.然后,采取主动传输策略,提高其检测精度并降低其开销.最后,将其与当前算法进行性能对比,对比结果表明MUDA在提高精度的同时将感知操作导致的吞吐量损失降低了65%.

感知无线电网络中考虑节点数据延时的分布式功率控制算法

研究感知无线电网络中分布式功率控制问题.为保证对主用户的干扰低于阈值,提出一种节点本地估计和信息交换的策略,不需要中心控制节点和辅助测量节点.优化目标是在满足数据传输延迟约束条件下最小化节点的发射功率,并证明此功率控制是凸优化问题.基于拉格朗日对偶分解原理,构造了次梯度迭代的分布式算法,并证明了分布式算法的收敛性.计算机仿真显示分布式算法可以快速收敛到最优解.

基于时间估计的动态频谱接入算法

基于先验知识模型,设计了基于信道剩余空闲时间估计的动态频谱接入算法:每个次用户根据感知历史维护信道剩余空闲时间的估计向量并周期进行更新,每个时隙开始时次用户选择剩余空闲时间估计最大的信道接入。对动态频谱接入算法的适应性问题进行了分析,并求得了次用户的最优传输时间长度。仿真结果表明,在给定的参数下,新算法的信道利用率比其他算法提高约5%-10%,同时对主用户的干扰保持最低。

CRN中基于遗传算法的信道分配方案研究

在感知无线电网络中,为了缓解终止频谱使用和切换造成的影响,最低干扰稳健型拓扑结构的构建问题(MIRTC)研究具有重要意义。将该问题表述为整数规划问题,并提出一种基于遗传算法的信道分配方案(GACA)来构建可将干扰降至最低的稳健型CR网络拓扑结构。其方法中,任意一个信道受到干扰,每一对数据源一目的地间仍可保持连接。此外,还提出了一种高效的Bisearch算法以进一步降低干扰。仿真结果表明,该算法可降低网络干扰,并有效地提升了网络吞吐量。

Determination of Threshold for Energy Detection in Cognitive Radio Sensor Networks

The Internet of Things （loT） is called the world＇ s third wave of the information industry. As the core technology of IoT, Cognitive Radio Sensor Networks （CRSN） technology can improve spectrum utilization efficiency and lay a sofid foundation for large-scale application of IoT. Reliable spectrum sensing is a crucial task of the CR. For energy de- tection, threshold will determine the probability of detection （Pd） and the probability of false alarm Pf at the same time. While the threshold increases, Pd and Pf will both decrease. In this paper we focus on the maximum of the difference of Pd and Pf, and try to find out how to determine the threshold with this precondition. Simulation results show that the proposed method can effectively approach the ideal optimal result.

Reputation-Based Hierarchically Cooperative Spectrum Sensing Scheme in Cognitive Radio Networks

Cooperative spectrum sensing in cog- nitive radio is investigated to improve the det- ection performance of Primary User （PU）. Meanwhile, cluster-based hierarchical coop- eration is introduced for reducing the overhead as well as maintaining a certain level of sens- ing performance. However, in existing hierar- chically cooperative spectrum sensing algo- rithms, the robustness problem of the system is seldom considered. In this paper, we pro- pose a reputation-based hierarchically coop- erative spectrum sensing scheme in Cognitive Radio Networks （CRNs）. Before spectrum sensing, clusters are grouped based on the location correlation coefficients of Secondary Users （SUs）. In the proposed scheme, there are two levels of cooperation, the first one is performed within a cluster and the second one is carried out among clusters. With the reputa- tion mechanism and modified MAJORITY rule in the second level cooperation, the pro- posed scheme can not only relieve the influ- ence of the shadowing, but also eliminate the impact of the PU emulation attack on a rela- tively large scale. Simulation results show that, in the scenarios with deep-shadowing or mul- tiple attacked SUs, our proposed scheme ach- ieves a better tradeoff between the system robustness and the energy saving compared with those conventionally cooperative sensing schemes.

A novel weighed cooperative bandwidth spectrum sensing for spectrum occupancy of cognitive radio network

In cognitive radio network(CRN), a secondary user(SU) may utilize the spectrum resource of the primary user(PU) and avoid causing harmful interference to the primary network(PN) via spectrum sensing. In the traditional time spectrum sensing, the SU cannot detect the PU's presence during its transmission, thus increasing interference to the PN. In this work, a novel weighed cooperative bandwidth spectrum sensing method is proposed, which allows multiple SUs to use part of the bandwidth to perform cooperative spectrum sensing throughout the whole frame in order to detect the PU's reappearance in time. The SU's spectrum efficiency is maximized by jointly optimizing sensing bandwidth proportion, number of cooperative SUs and detection probability, subject to the constraints on the SU's interference and the false alarm probability. Simulation results show significant decrease on the interference and improvement on the spectrum efficiency using the proposed weighed cooperative bandwidth spectrum sensing method.

Optimization of Multiband Spectrum Sensing for Cognitive Radio Networks under Sensing Capability Constrains

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 multi- band sensing as a two-parameter optimization prob- lem 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.

感知蜂窝网中具有多主用户的干扰对齐算法

针对具有多个主用户和多个次用户的TD(time division)感知蜂窝网络,给出一种多个主用户和多个次用户的干扰对齐算法。考虑1个宏蜂窝网络与2个小蜂窝网络共存,且同时利用同样频率进行通信的情况,宏蜂窝中有2个主用户,每个小蜂窝中有2个次用户。按照实际应用场景中干扰的多少将次用户分为2类,让主用户也参与次用户的干扰对齐,根据最大信干噪比方案设计干扰对齐算法,利用迭代方法求解。通过系统仿真显示,在主用户容量牺牲很小的情况下次用户的容量得到改善,同时系统的总容量得到提高。