基于超声波/INS信息融合的室内定位方法

室内定位方法中,低成本惯性导航系统(INS)的定位误差随着时间和距离的增加而积累,需要采用其他手段抑制误差发散。室内环境下GPS无法正常工作,从而失去对INS误差的抑制作用;因此,该文提出了基于超声波/INS信息融合的室内定位方法。以自主导引小车(AGV)为定位终端,根据超声波定位技术和非完整约束条件得到自主导引小车的位置和速度信息,并利用该信息辅助INS,通过卡尔曼滤波进行信息融合,从而抑制纯惯导情况下定位误差发散的问题。采用Matlab对所提出的室内定位方法进行仿真验证,结果表明,采用超声波/INS信息融合方法能将INS的误差抑制在一定范围内,该方法适用于室内移动物体的实时定位。     

基于TDOA的无线电超声波室内定位系统设计

介绍了一种基于TDOA并利用射频RF和超声波信号来测距的室内定位系统解决方案。该系统以nRF24E1内嵌的MCU为控制单元,nRF2401子系统和超声波收发器T/R40为测距工具,采用三个参考点来实现定位算法。详细论述了TDOA定位的原理,介绍了室内定位系统的发射模块、接收模块、接口电路及其相应的软件设计与实现。     

基于WLAN的室内定位方法

采取WLAN方式的室内定位成为一种新的定位方式,本文介绍了在WLAN定位中几种常用到的定位方法。     

基于朗伯模型参数估计的VLC室内定位优化算法

为实现高精度室内定位,本文设计了一种可见光 通信(VLC)室内定位系统,并通过 结合优化的朗伯模型、码分多址技术(CDMA)、三边定位算法而有效提升了定位精度和系统 扩展性。首先,每个发光二极管(LED)的ID信息经过直接序列调制后加载到LED驱动电路上 ,LED发出带有自身ID信息的灯光信号。在接收端通过光电探测器(PD)接收灯光信号,并 根据扩频码的正交性恢复出ID信息及接收信号强度(RSS),以此提高信道容量并增强系统 抗干扰能力。然后,根据朗伯光源模型,由三边定位算法得出待定位点的定位估计坐标。为 进一步提高精度,引入k最近邻(KNN)思想,采集适当的指纹点并由指纹点信息对每盏灯在 定位估计坐标处的朗伯光源模型参数进行估计,由优化后的朗伯模型计算出精度更高的定位 坐标。在1m×1m×1.35 m的空间区域中,进行本VLC室内定位系统 的实验测试。结果表明,提 出的高精度VLC室内定位系统的平均定位误差降低至2cm左右,其定位精度相比于传统三边 定 位算法提升了30%。此外,该系统方案所采用基于指纹点信息优化朗 伯模型参数的方法具备良好的实用扩展性,可实现广阔的应用场景。     

基于Wi-Fi的室内测时差定位方法

近年来室内Wi-Fi定位技术快速发展,已有多种定位方法投入商业运用。为满足用户对室内定位的更高精准度的要求,文章旨在研究基于室内Wi-Fi定位改进的测到达时差定位方法,采用高精度的相对时统、脉冲测时差及四站三双曲面定位技术,进一步提高定位精度,对Wi-Fi定位家族(体系)加强、补充和丰富。     

基于多数据源的室内定位方法探讨

数据定位系统在社会发展中的应用逐步扩大,定位技术水平也逐步实现多领域方向发展。数据定位系统中包括户外定位系统和室内定外系统两类。室内定位系统包括光感技术,无线传播技术等多重技术手段作为多数据源的定位发展的基本模式进行深度发展。市内定位技术的应用范围在日常生活中广泛应用于军事,民用领域,实现了移动通信技术的更新与发展。     

基于TDoA的室内定位方法研究

无线设备的普及,推动了无线定位系统的快速发展。针对室内环境的特点,提出了一种基于TDoA的室内定位算法,具有结构简单,计算复杂度低的特点。实验结果表明,提出的算法有比较低的平均定位误差和标准差,具有较好的性能。     

蜂窝网无线定位新技术

首先说明移动电话用户紧急情况下需要无线定位业务。接着简述无线定位的几种常用技术,并分别说明时分多址和码分多址两类蜂窝网所用无线定位技术的情况。最后提到无线定位的误差来源。     

一种无线网络时钟同步法的超声波室内定位系统设计

基于无线网络时钟同步法的超声波室内定位系统,提出了一种将超声波发射器和接收器件分离,并配置到2.4 GHz无线网络中,实现发射器和接收器之间的时钟同步和数据交换的定位方法.移动目标发送无线同步信号,延时后发出超声波,经硬质反射锥全向发射超声波信号.各信标单元收到无线同步信号后,延时启动定时器计时,当各信标单元收到超声波...     

Downlink multiple access schemes for transmitted reference pulse cluster UWB systems

Transmitted reference pulse cluster (TRPC) signaling was recently proposed for low data rate ultra‐wideband communications. Compared with the conventional transmitted reference (TR), TRPC has a more compact and uniform spacing for the reference and data pulses and therefore solves the implementation problem posed by the long delay line requirement in the conventional TR. In this paper, downlink multiple access issue is further investigated for TRPC systems. According to the TRPC signaling structure, both code division multiple access (CDMA) and time division multiple access (TDMA) methods are discussed. Theoretical analysis and simulation results show that TDMA outperforms CDMA in both bit error rate performance and throughput. Copyright © 2010 John Wiley & Sons, Ltd.     

多无人机扩频测控链路的扩频码分析

在码分多址（CDMA）的多无人机扩频测控链路中,多址干扰（MAI）是多目标系统需考虑的重要因素。在此类系统中,针对抗多址干扰的要求,设计具有相应互相关性能的扩频码是首要任务。从多无人机对抗多址能力的需求入手,分析了码速率、用户个数以及码的互相关性能对抗多址干扰能力的影响,得出了Kasami码型互相关性较好、序列部分相关会降低互相关性能的结论。仿真结果验证了理论分析的正确性。     

运动TDMA系统目标时差定位算法

根据时分多址(TDMA)系统的同步特征,利用TDMA运动目标准周期性信号的到达时间,提出了3种在三站时差定位系统中实现目标定位的算法.采用目标运动分析的方法,对TDMA目标位置的可观测性进行分析,提出了目标运动分析时差定位算法,利用目标航迹上多个位置的时差实现目标的定位.运用目标运动分析测距算法,提出了测距与传统时差定...     

cdma2000 1x前向功率分配分析

本文提出了一种在多径传输约束条件及不同的移动台运动速度条件下对前向信道链路进行功率分配的方法,这是根据导频信道和业务信道之间各自信号强度的相关性合理地分配前向链路中的信道发射功率.通过实验测试及理论推导,本文给出了这种相关性曲线,从而发现了最佳的导频信道功率,它能够在满足1%FER时使总发射功率最小.     

Linear and non‐linear space diversity combining algorithms over fading channels in TDMA systems

This paper investigates the performances of various adaptive algorithms for space diversity combining in time division multiple access (TDMA) digital cellular mobile radio systems. Two linear adaptive algorithms are investigated, the least mean square (LMS) and the square root Kalman (SRK) algorithm. These algorithms are based on the minimization of the mean‐square error. However, the optimal performance can only be obtained using algorithms satisfying the minimum bit error rate (BER) criterion. This criterion can be satisfied using non‐linear signal processing techniques such as artificial neural networks. An artificial neural network combiner model is developed, based on the recurrent neural network (RNN) structure, trained using the real‐time recurrent learning (RTRL) algorithm. It is shown that, for channels characterized by Rician fading, the artificial neural network combiners based on the RNN structure are able to provide significant improvements in the BER performance in comparison with the linear techniques. In particular, improvements are evident in time‐varying channels dominated by inter‐symbol interference. Copyright © 2001 John Wiley & Sons, Ltd.     

基于时空混沌码分多址系统性能分析

将时空混沌序列应用于DS—CDMA系统，给出了系统同步模型，并对系统性能进行了分析。结果表明：用混沌序列作为地址码的CDMA系统，可以有效地抑制干扰的影响，并能提高系统的传输效率，对CDMA系统性能的改善起到重要作用。     

Multiuser detectors for large CDMA random access systems over Rayleigh fading channels

In this paper, large code division multiple access (CDMA) random access systems employing the decorrelator and minimum mean square error (MMSE) detectors are investigated over Rayleigh fading channels under the assumption that both the number of users and the spreading gain tend to infinity, but their ratio converges to a constant. The signal to interference ratio (SIR) is shown to converge almost surely to a constant and the bit‐error rate (BER) is expressed as a function of the traffic load, transmission probability, channel coefficient, and distribution of transmission power. Furthermore, the throughput, the spectrum efficiency, and the stability region are analyzed and simulated. For dominating systems, it is shown that the MMSE detector achieves much higher throughput and spectral efficiency than decorrelator detector. Besides, it is also disclosed that, when the signal to noise ratio (SNR) is larger than an optimum value, the spectrum efficiency increases as the ratio of bit energy to noise power spectrum density (E_b/N₀) increases; however, when SNR is smaller than the optimum value, the spectrum efficiency decreases as E_b/N₀ increases. For ordinary stable systems, it is demonstrated that their stability region gets narrower as the traffic load increases. Copyright © 2010 John Wiley & Sons, Ltd.     

Design and analysis of synchronous dynamic frequency hopping code division multiple access communication system

An optical dynamic frequency hopping code division multiple access communication system is proposed. In this system, an electrically controlled tunable optical filter (TOF) is used to encode the modulated broadband light source. The code depends on the function set to the controller. Two-dimensional code, named functional code, is also proposed based of shifted sine function. The function defines the dynamic coding pattern of the central wavelength of the transmitted narrowband optical signal. Thus, the system will allow for an easy reconfiguration of the transmitter without the need for sophisticated encoder. At the receiver, a synchronized TOF with the same function is used as a decoder. The system is modeled and analyzed taking into account the multiple access interference, phase induced intensity noise, and thermal noise. The performance of this system is shown to be better compared with a fast frequency hopping system and a spectral amplitude coding system that uses either a Hadamard code, a modified quadratic congruence code (MQC), or a modified frequency hopping code (MFH).     

Parallel interference cancellation employing RAKE receiver with selection diversity for multiuser asynchronous DS/CDMA detectors in multipath Rayleigh fading channels

In this paper, we propose and analyse parallel CCI multistage cancellation by combining RAKE and selection diversity. In order to account for channel variations, adaptive implementation of decision thresholds at the RAKE output is suggested. It is shown to provide significant improvement over either hard or soft decision techniques especially in the near‐far situation. Investigation of the system robustness to imperfect channel parameter estimation is also presented. The communication channel is modelled as slowly varying Rayleigh fading discrete multipath channel. Copyright © 2002 John Wiley & Sons, Ltd.     

多跳Ad Hoc网络中支持MIMO的分布式拓扑未知时分多址接入协议的研究与分析

针对Ad Hoc网络和MIMO的有效结合,提出了适于多跳Ad Hoc网络的支持MIMO的分布式拓扑未知时分多址接入协议.该协议通过有限域无线网络设计算法在每帧给每个节点分配时隙且无需知道全网拓扑信息,这极大地减小了收集全网拓扑信息的开销.通过预约,每个节点在其分配的无干扰时隙并行发送MIMO链路的所有数据流,并在与其他节点共享的时隙发送MIMO链路的一部份数据流来解决传输冲突.同时推导出保证通过率和最佳帧长.结果显示动态分配MIMO的传输容量和抗干扰能力会极大地提高通过率.