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1.
High accuracy seamless positioning is required to support a vast number of applications in varying operational environments. Over the last few years, the global positioning system (GPS) has become the de facto technology for positioning applications. However, its performance is limited in indoor and dense urban environments due to multipath as well as signal attenuation and blockage. A number of techniques integrating GPS with other positioning technologies have been developed to address the limitations of standalone GPS in these difficult environments. While most of the developed techniques cover the outages of GPS in such environments, they do not provide acceptable performance, in terms of positioning accuracy, especially for some mission-critical (e.g. safety) applications. This paper proposes a tightly coupled (i.e. in the measurement domain) GPS/WiFi integration method which, in addition to addressing GPS outages, improves the overall positioning accuracy to the meter-level, thus satisfying the requirements of a number of location based services and intelligent transport systems applications. The performance of the proposed GPS/WiFi integration method is assessed for a number of scenarios in a simulation environment for an identified dense urban area in London, UK. 相似文献
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受多路径误差影响,GPS处于高反射环境下可导致接收机相位失锁,对点位坐标影响高达15cm;室内环境卫星无法锁定,GPS更是不能正常工作.本文引入了Skyhook XPS一体化混合定位系统,综合全球定位系统(GPS)、基站三角塔(Cell Tower Triangulation)和无线宽带(Wi-Fi)三种技术之优势,迅... 相似文献
3.
Location-based services: technical and business issues 总被引:13,自引:0,他引:13
Geographical Information System (GIS) and Global Positioning System (GPS) technologies are expanding their traditional applications
to embrace a stream of consumer-focused, location-based applications. Through an integration with handheld devices capable
of wireless communication and mobile computing, a wide range of what may be generically referred to as 'Location-Based Services'
(LBS) may be offered to mobile users. A location-based service is able to provide targeted spatial information to mobile workers
and consumers. These include utility location information, personal or asset tracking, concierge and route-guidance information,
to name just a few of the possible LBS. The technologies and applications of LBS will play an ever increasingly important
role in the modern, mobile, always-connected society. This paper endeavours to provide some background to the technology underlying
location-based services, and to discuss some issues related to developing and launching LBS. These include whether wireless
mobile technologies are ready to support LBS, which mobile positioning technologies can be used and what are their shortcomings,
and how GIS developers manipulate spatial information to generate appropriate map images on mobile devices (such as cell phones
and PDAs). In addition, the authors discuss such issues as interoperability, privacy protection and the market demand for
LBS.
Electronic Publication 相似文献
4.
2020年初暴发的新型冠状病毒肺炎(coronavirus disease 2019,COVID-19)疫情给全球人民生命安全和经济发展带来了严重影响。位置服务以庞大的地理空间信息数据库为依托,能向服务对象提供与地理信息相关的便捷、实时、精准的综合性服务,可很好地运用于紧急救灾、大流量人员追踪、复杂环境下的现场人员管控等事件中。事实证明,位置服务的优势特性在2020年春中国COVID-19疫情防控中起到了非常重要的作用。从北斗车联网平台、基于泛在定位的基础服务、时空大数据分析与疫情防控、智能导航机器人参与抗疫等多个方面阐述了中国COVID-19疫情下的位置服务应用。通过对这些应用及技术手段的分析总结,深化位置服务技术的内涵,可以为今后重大公共卫生事件的应急处置提供解决方案。 相似文献
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随着北斗卫星导航系统的逐渐完善,有关北斗系统定位的研究越来越深入,为了对比分析北斗系统和全球定位导航系统(GPS)定位的差异性,充分利用北斗地球静止轨道卫星(GEO)和倾斜地球同步轨道卫星(IGSO)高轨道卫星的特殊性,本文提出一种新的组合选星方法,选取卫星数较少且Position Dilution of Precision(PDOP)最小的北斗/GPS组合,分别对比分析北斗系统、GPS系统及其组合系统在楼顶开放环境和楼间恶劣环境下的定位效果。实验结果表明:北斗比GPS有更加稳定的定位效果,依据本文组合选星方法,利用少量卫星即可获得较好的定位精度。 相似文献
6.
The location requirements for emergency callers outside urban areas can hardly be fulfilled without global navigation satellite
systems (GNSS). Consequently, interest in positioning techniques based on use of a GNSS such as GPS or on the cellular network
infrastructure itself is growing rapidly in the mobile-telephone community. Moreover, the increasing demand for commercial
location-based services (LBS) has driven cellular-phone and network manufacturers to focus on positioning solutions which
are even more accurate than the regulatory mandates for positioning of emergency callers. One example of these upcoming LBS
is our PARAMOUNT project, which aims at improving user-friendly info-mobility services for hikers and mountaineers by combining
wireless communications (GMTS), satellite navigation (GNSS) and geographic information systems (GIS), based on a mobile client/server
architecture. The availability of mobile phones or PDAs with combined GNSS and cellular network-based wireless communication
on a high integration level is one primary demand of such LBS applications. Based on this, we will give some initial answers
to the question of whether mobile handset architecture synergies exist for the combination of GNSS with wireless location
in CDMA cellular wireless networks. In order to identify synergies, we will outline similarities and differences between wireless
communication and satellite navigation. In this respect, we pay particular attention to the so-called RAKE receiver architecture
employed in mobile CDMA cellular handsets. Our initial investigations will show that the RAKE receiver architecture, on which
mobile CDMA cellular handsets are based, will most likely be the one most suitable for achieving synergies between the two
positioning techniques within the same mobile handset architecture. Consequently, several receiver components could be used
to handle both types of signals (navigation and communications), resulting in a reduction of manufacturing costs and in a
decrease in energy consumption.
Electronic Publication 相似文献
7.
A fuzzy logic map matching for wheelchair navigation 总被引:1,自引:0,他引:1
Global Positioning System (GPS) plays a central role in solving the location-based needs of wheelchair users and efficient route guidance. An essential process in wheelchair navigation is matching the position obtained from GPS or other sensors on a sidewalk network. This process of map matching in turn assists in making decisions under uncertainty. However, GPS-based wheelchair navigation systems have difficulties in tracking wheelchairs in urban areas due to poor satellite availability. To overcome this, a fuzzy logic-based algorithm is applied to effectively perform matching wheelchair movements on sidewalks. Fuzzy logic, based on fuzzy reasoning concepts, in many circumstances can take noisy and imprecise input to yield numerically accurate output. Experiments on a university campus validate it practicable. 相似文献
8.
Rod Bryant 《GPS Solutions》2002,6(3):138-148
A key requirement for emergency call location (e.g. E911), for robust operation of location-based m-commerce systems and for
telematics systems is that the location technology be able to operate in urban canyons and inside buildings. We start from
a definition of the target environments, which includes multi-level parking garages, office buildings and homes, but not underground
parking garages or tunnels. Based on experience in these target environments and understanding of typical applications we
derive specific requirements for sensitivity and acquisition speed. The primary problems associated with weak signal operation
are as follows. (1) In conventional GPS receivers sampling at the correlator output typically occurs at a sampling interval
of the order of 1 ms. With weak signals, however, the signal-to-noise ratio of these samples is too low to support lock-in
of a phase-locked or frequency-locked loop. (2) With weak signals, the signal-to-noise ratio is too low to support the extraction
of the 50BPS navigation message from the signal. Therefore, aiding data is required from an external source. (3) Because the
data cannot be extracted, it is not possible for the receiver to synchronize to the incoming bits, words or subframes. Therefore,
it is not possible to construct pseudoranges without prior information. (4) The paper describes Sigtec Navigation's subATTO technology. This technology provides sensitivity down to –185 dBW (19 dBHz assuming NF of 1.5 dB and no other implementation
loss). This is 5 dB below an attoWatt (10–18 W) and has been shown to provide reliable positioning inside buildings, multi-level parking garages and in urban canyons
without any aiding at all. The paper describes the patented signal processing scheme, how ambiguity resolution and time synchronization
are achieved, the wireless assistance technique, the acquisition strategy and the use of scanning channels. Results are presented
from trials in a multi-level parking garage. The results obtained in most parking garages are similar to these in terms of
availability of fixes, signal strengths received and location accuracy achieved. The performance achieved in multi-level parking
garages is rarely worse than this. One of the major impediments to practical application of weak signal-processing schemes
is the limited dynamic range imposed by the GPS C/A code signal structure. This problem is discussed along with the problems
of multipath distortion in the context of telematics operation in urban canyons. A realistic urban accuracy goal of 20 m for
95% of fixes is proposed based on experience with GPS and dead reckoning. Enhancements under development will provide sensitivity
of –188 dBW, which will provide continuous availability within a broader range of indoor environments. For practical applications,
this will require the use of modern 'search engine' hardware for acceptable acquisition speed. As the paper shows, this sensitivity
is near the practical limit of sensitivity with acceptable acquisition times and dynamic capability.
Electronic Publication 相似文献
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高灵敏度GPS技术的研究进展 总被引:10,自引:1,他引:10
介绍了高灵敏度GPS(High—Sensitivity GPS)技术的研究进展及高灵敏度GPS技术的应用前景和研究意义。分析了GPS信号在室内、森林、城市等一般GPS接收机无法应用环境的特性,综述了高灵敏度GPS关键技术的基本原理。高灵敏度GPS技术的核心就是室内环境微弱GPS信号的捕获技术,重点介绍了捕获室内环境弱GPS信号的基本方法,总结了各种捕获算法的特点。 相似文献
11.
In the complex urban environments, land vehicle navigation purely relying on GNSS cannot satisfy user needs due to the loss of satellite signals caused by obstructions such as buildings, tunnels, and trees. To solve this problem, we introduce a GPS-/MSINS-/magnetometer-integrated urban navigation system based on context awareness. In this system, the data from the Micro Strapdown Inertial Navigation System (MSINS) are used to analyze and detect the context knowledge of vehicles, whose sensor errors can be compensated by the heuristic drift reduction algorithm for different motion situations. When GPS is available, the vehicle position can be estimated by unscented Kalman Filter, whereas in the case of GPS outages, the vehicle attitude is provided by an attitude and heading reference system and the motion constraints-aided algorithm is used to complete the positioning. In the experiment validation, the integrated navigation system is set up by low-cost inertial sensors. The result shows that the proposed system can achieve high accuracy when GPS is available. For most of the time without GPS, the system can guarantee the positioning precision of 10 m and compensate the errors of MSINS effectively, which fully satisfies positioning needs in complex urban environments. 相似文献
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Navigation applications and location-based services are now becoming standard features in smart phones. However, locating
a mobile user anytime anywhere is still a challenging task, especially in GNSS (Global Navigation Satellite System) degraded
and denied environments, such as urban canyons and indoor environments. To approach a seamless indoor/outdoor positioning
solution, Micro-Electro-Mechanical System sensors such as accelerometers, digital compasses, gyros and pressure sensors are
being adopted as augmentation technologies for a GNSS receiver. However, the GNSS degraded and denied environments are typically
contaminated with significant sources of error, which disturb the measurements of these sensors. We introduce a new sensor,
the electromyography (EMG) sensor, for stride detection and stride length estimation and apply these measurements, together
with a digital compass, to a simple pedestrian dead reckoning (PDR) solution. Unlike the accelerometer, which senses the earth
gravity field and the kinematic acceleration of the sensor, the EMG sensor senses action potentials generated by the muscle
contractions of the human body. The EMG signal is independent of the ambient environment and its disturbance sources. Therefore,
it is a good alternative sensor for stride detection and stride length estimation. For evaluating the performance of the EMG
sensor, we carried out several field tests at a sports field and along a pedestrian path. The test results demonstrated that
the accuracy of stride detection was better than 99.5%, the errors of the EMG-derived travelled distances were less than 1.5%,
and the performance of the corresponding PDR solutions was comparable to that of the global positioning system solutions. 相似文献
15.
Ramón Piedrafita Rubén Béjar Rubén Blasco Alvaro Marco F. Javier Zarazaga-Soria 《International Journal of Digital Earth》2018,11(8):761-782
In the current world, it is easy to listen that everybody and everything is connected. Over this connected world, the concept of location-based services has grown in order to provide digital services in everyplace and at every time. Nevertheless, this is not 100% true because the connection is not guaranteed for many people and in many places. These are the Degraded Communications Environments (DCE), environments where the availability of high-speed communications is not guaranteed in at least the 75% of the time. This paper works over the experience of a previous work in developing light protocols that do not need broadband for communication. This work provides an extension of these protocols for the inclusion of mobile devices as elements of the communication process and a set of libraries to allow the development of applications in DCE. The work done has involved the development of two frameworks: an Android framework that makes the incorporation of Android devices easier and a server-based framework that provides the server side for the development of the referred applications. A use case that uses these two frameworks has been developed. Finally, all technology developed is available throw a public Git repository. 相似文献
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《International Journal of Digital Earth》2013,6(2):158-184
Abstract The Global Positioning System (GPS) is expected to play an integral role in the development of digital earth; however, the GPS cannot provide positioning information in regions where a majority of the population spends their time, that is, in urban and indoor environments. Hence, alternate positioning systems that work in indoor and urban environments should be developed to achieve the vision of digital earth. Wi-Fi-based positioning systems (WPS) stand out because of the near-ubiquitous presence of the associated infrastructure and signals in indoor environments. The WPS-based fingerprinting is the most widely adopted technique for position determination, but its accuracy is lower than that of techniques such as time of arrival and angle of arrival. Improving the accuracy is still a challenging task because of the complex nature of the propagation of Wi-Fi signals. Here, a novel server-based, genetic-algorithm-optimized, cascading artificial neural network-based positioning model is presented. The model is tested in 2D and 3D indoor environments under varying conditions. The model is thoroughly investigated on a real Wi-Fi network, and its accuracy is found to be better than that of other well-known techniques. A mean accuracy of 1.9 m is achieved with 87% of the distance error within the range of 0–3 m. 相似文献
18.
位置推荐是地理社交网络的重要应用,针对城市范围内多用户集体社交活动的规划需求,在顾及道路通达性和时间成本的情况下进行位置推荐算法的研究。针对城市路网结构特征和导航路线规划特点,在地图应用程序接口的支持下,利用各用户间导航路线上的特定点自动识别、构建区域实现位置推荐,平衡多个用户到推荐地点的可到达性和时间成本。实验结果验证了所提方法的有效性,在地理社交网络上可以为城市多用户的集体活动提供有效的位置推荐方案。 相似文献
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