基于射线跟踪的特征匹配定位技术研究

【作者】 赵毅；

【导师】 卓永宁；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2011， 硕士

【摘要】 近年来,伴随着移动通信系统快速发展,室内无线定位技术逐渐成为研究的焦点。室内定位技术主要应用于车站、医院、机场、商场、博物馆等环境,其服务可以帮助应对引导、跟踪、消防、反恐等紧急事件。在室内主要运用基于基站和移动终端的定位技术时,由于建筑理念、风格成千上万,建筑材料、结构、尺度、摆设等各不相同,其带来的非视距传播严重影响了定位精度,成为限制这类定位技术应用于室内的关键因素。基于信号地图的定位技术是克服非视距的主要方法之一。在研究了基于射线跟踪的序列定位算法后,提出了基于小波消噪的射线跟踪序列匹配定位算法。该算法通过小波变换阈值消噪方法对目标的冲激响应序列进行消噪处理,然后用消噪后的序列与已知位置信标点的冲激响应序列进行匹配定位。仿真表明算法具有较高的定位成功率,有效地降低了环境噪声对定位特征的影响。在对比了目前基于信号地图的城市及室内定位技术的基础上,提出基于小波变换的特征匹配射线跟踪定位算法。该算法利用射线跟踪算法从接收点反向跟踪所有多径信号并以多径信号的冲激响应来模拟信道,与实测信道建模方式相比简化了工作量。然后通过小波变换从冲激响应序列中分解出包含定位特征的小波系数矩阵,该系数矩阵不仅能够反映信标点发出无线电波在传播过程中信号强度的衰减情况,而且包含信号强度衰减的时间信息,比用信号强度作为定位特征提高了完备性。为了方便建立信号地图,减少匹配算法的复杂度,将小波系数矩阵中分解得到的奇异值向量作为建立本算法信号地图的特征。计算机仿真表明,本算法提取的定位特征具有良好的稳定性,相比用接收信号强度作为特征的定位算法,本算法可以得到更精确的定位结果。算法的定位精度符合室内定位服务要求,而且随着区域内信标点密度增大而提高。更多还原

【Abstract】 With the fast development of mobile communication system in recent years, the indoor wireless location technology is gradually becoming a research highlight. It is applied in the various circumstances including station, hospital, airport, mall, museums and so on, and its outcome is used for handling with emergency such as leading, guidance, fire prevention and counter-terrorism.The location technology based on base stations and mobile equipments cannot work in the indoor environment because of the Non-Line-of-sight (NLOS) propagation. The different architectural concept, style, structure, size or display brings out the NLOS propagation which is the key factor to limit this kind of location technology. The location technology based on signal map is one of major ways to cope with the NLOS propagation.After a number of researches on the sequence location algorithm based on ray-tracing, the sequence of ray-tracing location algorithm based on wavelet de-noising is presented. The de-noising threshold based on wavelet transform is utilized for eliminating the noise from the impulse response of the target, and then the impulse response compares with the ones of position-known beacons which are pre-built by the ray-tracing technology to estimate user location. The simulation demonstrates that the algorithm has a high success rates to locate users’positions, and reduces the impact of the noise effectively.After the analysis of the existing city and indoor location technologies based on signal map, this paper further puts forward a ray-tracing location algorithm related with channel feature extraction and matching based on wavelet transform. This algorithm first obtains the multi-path signals from the receiver reversely and calculates their impulse response using the ray-tracing method, which simplifies the work comparing with the realistic measurements modeling. Then we extract the feature of the channel from the wavelet transform coefficient matrix of the discrete impulse response sequence. The feature of the channel not only contains the information of how much signal strength decline, but also when the decline happens. It is more complete than the signal strength sequence. In order to build the signal map conveniently and reduce the complication of the matching algorithm, the singular value vector extracted from the wavelet coefficient matrix by singular value decomposition is used as the feature of the signal site. Computer simulation shows that the character of location calculated from the algorithm has excellent stabilization. The location results demonstrate the ability of our algorithm to estimate user location with a higher degree of the accuracy than the algorithm that uses the receive signal strength as the characteristic of the signal map. The overall accuracy of locating objects satisfies the need of the inside location service, and the performance becomes better as the beacon density increases.更多还原