基于分簇传感网的RSSD/TDOA协同定位方法

针对基于能量有限的分簇传感网实现对非配合辐射源的高精确度无源定位问题,提出了一种适用于传感网的接收信号强度差fRSSD）定位方法,并在其相关性能分析基础上提出了以RSSD定位为辅、到达时间差（TDOA）定位为主的两轮协同定位方案,即以RSSD定位结果作为目标位置初估计,并根据各簇在该初估计位置处的TDOA定位CRB,选择部分预期定位精确度较高的簇参与进一步的TDOA定位,最后通过对这些簇定位结果的加权平均得到最终的目标位置估计。仿真结果表明,相比基于GDOP的簇选择标准和定位融合方法,提出的改进措施提高了定位精确度,而RSSD／TDOA协同定位方案在保证较高定位精确度的同时,有效地减轻了网络负载,延长了网络生命周期,具有较好的工程应用前景。     

高精度无源定位技术的研究

通过对现有的无线网络定位技术(包括网络定位、终端定位、有源定位、无源定位)和各种定位算法(包括具有解析表达式解的算法、递归算法)的深入研究和分析,提出一种高精度的无源定位技术方案。这种定位技术采用无源网络定位模式,同时计算多个TDOA值,由地面定位站根据多个TDOA值解算出位置,以提高定位精度。面对用户对定位精度要求的日益提高,高精度地面无源定位系统将会有广大的市场前景。     

基于Chan氏算法和Taylor级数展开法的协同定位方法

该文分析讨论了Chan和泰勒两种TDOA定位算法的优缺点,并在此基础上提出了基于 Chan氏算法(1994)和Taylor级数展开法(1976)的协同定位方法。通过在不同信道环境下对协同定位 方法进行仿真,表明该方法在信道环境恶劣时能够有效地提高定位精度。     

基于WLAN移动终端的无线定位技术

介绍了WLAN的技术特点和基于WLAN移动终端的无线定位技术的原理,提出在WLAN中使用TDOA定位的Chan算法对移动终端进行位置估计,再使用残差加权方法进行非视距(NLOS)误差抑制,提出了新的定位残差定义方式,通过仿真证明了按该方式进行残差加权,在多个NLOS误差时具有较好的整体抑制效果,并提供采用"平均定位精度提高百分率"(ALAEP)来评定残差加权方法抑制NLOS误差的平均性能.     

蜂窝网络中基于TDOA的CHAN定位算法性能分析

基于用户位置的应用已经成为移动数据业务的重要组成部分,使得蜂窝系统用户定位技术成为蜂窝移动通信领域的研究热点。CHAN算法是一种优良的利用电波到达时间差（TDOA）的定位算法。该算法的特点是计算量小,在视距（LOS）传播环境下有较高的精度。通过在高斯噪声和实际信道两种不同的传播环境下对CHAN算法进行仿真,通过对算法的仿真分析,结果表明在不同的基站以及不同环境下,CHAN算法的定位精度有着显著的差别。     

交互多模算法在蜂窝网指纹定位技术中的应用

针对目标运动及无线信道动态衰落特性对用户位置估计波动较大的影响,利用基于卡尔曼滤波的交互多模算法的特性,并将其应用于蜂窝网指纹定位技术中.根据K近邻匹配算法估计出用户位置坐标,然后利用交互多模算法对用户位置坐标进行滤波处理,提高定位精度.通过对真实环境下数据的处理和分析,基于卡尔曼滤波的交互多模算法能有效提高定位精度.     

混合Taylor算法/遗传算法在TDOA定位中的应用

对基于Taylor算法/遗传算法的混合定位算法进行了研究。由于Taylor算法初始值的选取对定位结果影响很大,在初始位置选择不好的情况下,算法将很难保证收敛。而在实际应用中,初始位置是很难确定的,这也限制了Taylor算法的定位精度的提高。因此,可以先通过遗传算法,对测量数据进行初始定位,将定位的结果作为Taylor算法的初始值,然后再利用Taylor算法进行定位运算,确定用户坐标。因此我们确信该混合算法是合理的,能有效提高定位精度。     

可见光重构指纹室内定位算法研究

提出一种可见光重构指纹室内定位算法(RFP),通过融合到达时间差(TDOA)算法和指纹算法可快速完成室内高精度定位。该算法首先利用TDOA算法多次估计得到的解集定义一个区域,然后在该区域中构建三维精细指纹库,再利用匹配算法定位未知节点。仿真结果表明,该算法的平均定位误差约为0.1719m,与传统的TDOA算法相比,提高了定位精度,与传统精细指纹算法相比,节省了定位时间。     

基于TDOA算法的差分UWB室内定位系统研究

超宽带UWB定位技术在受到电磁干扰、NLOS等情况影响时,实际定位环境变得复杂,造成实际定位精度不高、定位稳定性差。通过借鉴差分GPS技术,以TDOA-UWB室内定位技术为基础,提出差分UWB定位算法。同时结合权重滑动平均法,研究并提出基于TDOA算法的差分UWB室内定位系统,以Hainan EVK 2.0系统作为实验平台进行相关的测试实验。实验结果表明,基于TDOA算法的差分UWB室内定位系统能有效提高定位精度和定位稳定性,在受到外界干扰的情况下,定位误差整体降低23%。     

一种基于TDOA的三基站移动通信定位算法

通过建立到达时间差（TDOA）定位模型，并运用牛顿迭代法对模型进行求解，给出了一种基于TDOA的三基站移动通信定位算法。该算法不需要新建坐标系来确定三基站的经纬高坐标，即可对移动终端进行三维定位。方针结果表明，该算法定位精度较高，可以满足应用需求。     

Optimal cooperative strategy based on quantum bat for cognitive radio of energy harvesting

In order to reduce energy consumption and improve spectral efficiency of the cognitive relay wireless communication system in 5G network,an optimal cooperative transmission strategy of information and energy was designed for cognitive relay radio with wireless energy harvesting.For the proposed optimal cooperative strategy,the maximal throughput formula and outage probability of secondary user were deduced.In order to resolve the derived maximum throughput equation,a quantum bat algorithm which was based on the optimization mechanism of quantum computing and bat algorithm was designed to solve the deduced equation,and the optimal cooperative transmission scheme for information and energy could be obtained.Simulation results show that the proposed optimal cooperative strategy not only can meet the information transfer demand of primary user,but also can realize the energy self-supply of the secondary user system and improve the communication quality of the secondary user.The proposed optimal cooperative strategy has a better performance than the cooperative strategy of existing cognitive relay radio for different simulation scenarios.     

基于三个认知用户的多分支频谱感知方法

为了在认知无线电网络中有效地感知出授权用户,通过在无线通信网络中对多分支协作分集方式的研究,提出了在3个认知用户组成的认知无线电网络中,2个认知用户作为1个认知用户的中继用户,采用多分支协作分集方式感知授权用户。对其检测性能进行了理论分析,表明该方法是一种有效的感知方法,并且在低信噪比环境下,也可以有效地提高检测概率和降低检测时间从而提高网络的敏捷度增益。实验仿真结果证明,在低信噪比的环境下,该方法也可以获得较好的性能。     

基于统计可信度的压缩感知协作频谱检测算法

压缩感知为认知无线电的宽频谱感知提供了一种新的方法和思路。基于压缩感知的原理,提出了一种多认知用户协作场景下基于用户统计可信度的协作频谱检测算法。该算法使用正交匹配协作追踪算法获得认知区域内的频谱占用情况,根据不同认知用户频谱检测的历史准确度综合判定用户感知结果的统计可信度。仿真结果表明,该算法在不同用户数、不同采样值、不同信噪比变化范围下其检测性能均优于传统算术平均方法,有效改善了检测性能。     

Cooperative automatic modulation recognition in cognitive radio

In this article, a new effective method of cooperative modulation recognition (CMR) is proposed to recognize different modulation types of primary user for cognitive radio receivers. In the cognitive radio (CR) system, two CR users respectively send their feature parameters to the cooperative recognition center, which is composed of back propagation neural network (BPNN). With two users' cooperation and the application of an error back propagation learning algorithm with momentum, the center improves the performance of modulation recognition, especially when one of the CR users' signal-to-noise ratio (SNR) is low. To measure the performance of the proposed method, simulations are carried out to classify different types of modulated signals corrupted by additive white Gaussian noise (AWGN). The simulation results show that this cooperation algorithm has a better recognition performance than those without cooperation.     

认知无线电最优线性协作宽带频谱感知

本文提出了基于最优线性协作的宽带频谱感知方案。通过次级用户之间的协作,为认知网络的频谱感知提供分集,利用融合中心融合多个次级用户的宽带频谱感知数据来获取最优权重,并生成全局判决统计量,最终使用全局阈值完成最后的检测判决。由于所提出的两种协作宽带感知方案或需要精确地估计授权用户的信号强度和噪声方差,或感知性能不足,因而,还提出一种更易实现的方案。理论分析和仿真结果表明,本文所提出的协作感知方案可以有效地提高频谱感知性能,并且性能优于传统等增益合并方案。      

Enhancing localization accuracy of collaborative cognitive radio users by internal noise mitigation

Location information of mobile primary users is one of the essential requirements for an underlay cognitive radio user to utilize the licensed spectrum efficiently. The performance of various location-based applications such as global navigation satellite system, device to device communication in dense urban 5G network also depends on the localization accuracy. In this paper, a collaborative localization scheme based on received signal strength has been proposed. The weighted centroid localization algorithm has been applied in the proposed network scenario to compute location coordinates of the mobile primary user. Since the channel noise effects are random and unavoidable, this paper has focused on the mitigation of the internal noise by designing a suitable reconfigurable FIR filter after the demodulator stage of a cognitive radio receiver circuit to improve precision of signal measurement during primary user localization. The localization error rate has come down to (1.3–1.62) % after internal noise mitigation. The enhancement in the localization accuracy improves the overall spectrum utilization efficiency and reduces the miss detection and false detection probabilities in the proposed underlay network.

     

Joint cooperative spectrum sensing and channel selection optimization for satellite communication systems based on cognitive radio

Cognitive radio has attracted considerable attention because of its ability to make full use of the available spectrum resources for wireless terrestrial communication networks. In addition, the satellite communication scenario, which requires a transparent air interface to integrated/hybrid Satellite–Terrestrial communication systems and provides a supplement for other multimedia services, will cause frequency scarcity. Satellite communication systems based on cognitive radio are available under scenarios that involve transmission with changing communications. In this paper, a cooperative spectrum‐sensing algorithm based on a time or bandwidth‐based cooperative spectrum‐sensing model of an integrated/hybrid cooperative satellite communication system is proposed. Moreover, the concept of weighted cooperative spectrum sensing is introduced. Compared with the traditional single‐user spectrum‐sensing algorithm, the cooperative spectrum sensing is able to cope with the interference to the primary user caused by a secondary user better. In addition, multiple earth stations that use some part of the bandwidth cooperatively to perform spectrum sensing throughout the whole frame can detect the presence of primary user in time. The satellite component combines the sensing results from earth stations to reach a final decision, and the optimal combination weights to maximize the detection probability of the secondary user are obtained. Numerical results that demonstrate the performance of the proposed algorithm are presented. Copyright © 2015 John Wiley & Sons, Ltd.     

协作频谱感知在认知网络中的应用

认知无线电能够灵敏感知周围环境的变化,通过频谱感知功能发现频谱空洞,使得认知无线电能够与周围通信环境相适应。在认知无线电网络中,认知用户（次用户）必须连续地监控频谱,检测主用户是否存在。如果主用户存在,次用户必须尽快地退出该频段,从而不影响主用户。在文中采用一种协作机制,即两用户进行协作频谱感知,从而提高主用户的检测率,减少了检测时间,并且得到捷变增益。我们用Matlab给出仿真结果。     

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.