Evaluation for Vehicle Positioning in Urban Environment Using QZSS Enhancement Function

2012 ◽  
Vol 24 (5) ◽  
pp. 894-901
Author(s):  
Mitsunori Kitamura ◽  
◽  
Taro Suzuki ◽  
Yoshiharu Amano ◽  
Takumi Hashizume ◽  
...  
Keyword(s):  
Urban Environment ◽  
Performance Enhancement ◽  
Elevation Angle ◽  
Satellite System ◽  
High Elevation ◽  
Urban Environments ◽  
Gps Positioning ◽  
Positioning Errors ◽  
Evaluation Test ◽  
Gps Accuracy

In this paper, we have evaluated the performance and availability enhancement of Quasi-Zenith Satellite System (QZSS) in urban environments. In urban environments, QZSS can be expected to be fairly effective because of the high elevation angle of satellite and enhancement functions. Therefore, we conducted performance and availability enhancement evaluation tests to verify thus. In performance enhancement evaluation test, in order to evaluate the improvement of GPS accuracy by L1 Submeter-class Augmentation with Integrity Function (L1-SAIF) broadcasted by QZSS satellite, we compared the positioning errors of only GPS positioning and L1-SAIF positioning in open sky environment. In availability enhancement evaluation test, we performed the static and kinematic observation test. In static observation test, in order to evaluate the improvement of GPS accuracy by availability enhancement, we observed GPS and QZSS statically in narrow-sky environment. And we compared the positioning errors of only GPS positioning and positioning using availability enhancement. In kinematic observation test, in order to evaluate the availability of QZSS based on the visibility of QZSS satellite in urban environment, we observed QZSS and SBAS from moving vehicle. And we compared the visibility of QZSS and SBAS satellites. From these evaluation tests, it was confirmed that the performance and availability enhancement of QZSS have high availability and effectiveness.

scholarly journals PERFORMANCE ANALYSIS OF DOPPLER AIDED GPS/QZSS PRECISE POSITIONING FOR LAND VEHICLES

2013 ◽  
Vol 20 (1) ◽  
pp. 85-96 ◽  
Author(s):  
Byung-Hyun Lee ◽  
Gyu-In Jee
Keyword(s):  
Urban Area ◽  
Elevation Angle ◽  
Satellite System ◽  
Transport Systems ◽  
Doppler Measurement ◽  
Precise Positioning ◽  
Multipath Error ◽  
Precise Position ◽  
Land Vehicles ◽  
Positioning Errors

ABSTRACT For ITS (Intelligent Transport Systems), especially for land vehicles, precise position is the prime information. GNSS is the most popular navigation system. Generally, ITS demands lane distinguishable positioning accuracy. However urban area is most environments of land vehicles and the signal blocks of satellite with low elevation angle, multipath error and etc. make unreliable positioning results. Especially, lack of number of visible satellites (fewer than 4 satellites) cannot provide positioning results. QZSS (Quasi-Zenith Satellite System) which operated by Japan has high interoperability. In addition, its elevation angle is very high in long time in Korea. It means QZSS signal can be received in urban area and it can be great advantage for land vehicles. The most positioning errors are occurred by multipath, cycle slip, and etc. For example, multipath error is unexpected momentary error. In order to reduce position error, smoothing technique in position domain is needed. In this paper, precise positioning for land vehicles was evaluated. First, by using QZSS, probability of navigation solution was enhanced. Second, the reliability is improved by smoothing positioning result using Doppler measurement. The analysis was performed by trajectory analysis using precise map data.

scholarly journals Effect Analysis of GNSS/INS Processing Strategy for Sufficient Utilization of Urban Environment Observations

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 620
Author(s):  
Bo Shi ◽  
Mengke Wang ◽  
Yunpeng Wang ◽  
Yuntian Bai ◽  
Kang Lin ◽  
...  
Keyword(s):  
Urban Environment ◽  
Real Data ◽  
Satellite System ◽  
Urban Environments ◽  
Integrated System ◽  
Coupled Systems ◽  
Integer Ambiguity ◽  
Processing Strategy ◽  
Effect Analysis ◽  
Tightly Coupled

The occlusion of buildings in urban environments leads to the intermittent reception of satellite signals, which limits the utilization of observations. This subsequently results in a decline of the positioning and attitude accuracy of Global Navigation Satellite System (GNSS)/Inertial Navigation System (INS) integrated system (GNSS/INS). This study implements a smooth post-processing strategy based on a tightly coupled differential GNSS/INS. Specifically, this strategy used the INS-estimated position to reinitialize integer ambiguity. The GNSS raw observations were input into the Kalman filter to update the measurement. The Rauch–Tung–Striebel smoothing (RTSS) algorithm was used to process the observations of the entire period. This study analyzed the performance of loosely coupled and tightly coupled systems in an urban environment and the improvement of the RTSS algorithm on the navigation solution from the perspective of fully mining the observations. The experimental results of the simulation data and real data show that, compared with the traditional tightly coupled processing strategy which does not use INS-aided integer ambiguity resolution and RTSS algorithm, the strategy in this study sufficiently utilized INS observations and GNSS observations to effectively improve the accuracy of positioning and attitude and ensure the continuity of navigation results in an obstructed environment.

scholarly journals Multipath modeling and mitigation by using sparse estimation in global navigation satellite system-challenged urban vehicular environments

2020 ◽  
Vol 17 (5) ◽  
pp. 172988142096869
Author(s):  
Yue Yuan ◽  
Feng Shen ◽  
Dingjie Xu
Keyword(s):  
Global Navigation Satellite System ◽  
Satellite System ◽  
Urban Environments ◽  
Navigation Satellite ◽  
Multipath Mitigation ◽  
Sparse Estimation ◽  
Positioning Errors ◽  
Net Method ◽  
Global Navigation ◽  
Global Navigation Satellite

Multipath interference has been one of the most difficult problems when using global navigation satellite system-based vehicular navigation in urban environments. In this article, we develop a multipath mitigation algorithm exploiting the sparse estimation theory that improves the absolute positioning accuracy in urban environments. The navigation observation model is established by considering the multipath bias as additive positioning errors, and the assumption for the proposed method is that global navigation satellite system signals contaminated due to multipath are the minority among the received signals, which makes the unknown bias vector sparse. We investigated an improved elastic net method to estimate the sparse multipath bias vector, and the global navigation satellite system measurements can be corrected by subtracting the estimated multipath error. The positioning performance of the proposed method is verified by analytical and experimental results.

scholarly journals Measurement Strategies for Street-Level SLAM Laser Scanning of Urban Environments

2020 ◽  
Vol 27 (1) ◽  
pp. 1-19
Author(s):  
Aino Keitaanniemi ◽  
Antero Kukko ◽  
Juho-Pekka Virtanen ◽  
Matti T. Vaaja
Keyword(s):  
Urban Environment ◽  
Laser Scanning ◽  
Point Clouds ◽  
Satellite System ◽  
Urban Environments ◽  
Measurement Unit ◽  
Street Level ◽  
Measurement Strategy ◽  
Laser Scanners ◽  
Measurement Strategies

Data collection for street-level mapping is currently executed with terrestrial (TLS) or mobile laser scanners (MLS). However, these methods have disadvantages such as TLS requiring a lot of time and MLS being dependent on the global navigation satellite system (GNSS) and an inertial measurement unit (IMU). These are not problems if we use simultaneous localization and mapping (SLAM) based laser scanners. We studied the utility of a SLAM ZEB-REVO scanner for mapping street-level objects in an urban environment by analyzing the geometric and visual differences with a TLS reference. In addition to this, we examined the influence of traffic on the measurement strategy. The results of the study showed that SLAM-based laser scanners can be used for street-level mapping. However, the measurement strategy affects the point clouds. The strategy of walking trajectory in loops produced a 2 cm RMS and 4-6 mm mode of error even in not optimal situations of the sensor in the urban environment. However, it was possible to get an RMS under 2.2 cm and a 32 cm mode of error with other measurement strategies.

scholarly journals Decoding Performance Analysis of GNSS Messages with Land Mobile Satellite Channel in Urban Environment

Electronics ◽  
2018 ◽  
Vol 7 (11) ◽  
pp. 273
Author(s):  
Jing Ke ◽  
Xiaochun Lu ◽  
Xue Wang ◽  
Xiaofei Chen ◽  
Sheng Tang
Keyword(s):  
Urban Environment ◽  
Performance Improvement ◽  
Elevation Angle ◽  
Ldpc Code ◽  
Multipath Fading ◽  
Satellite System ◽  
Mobile Satellite ◽  
Global Navigation Satellite ◽  
Sky Conditions ◽  
Channel Properties

Demand for Global Navigation Satellite System (GNSS) applications in the urban environment has experienced a remarkable growth in recent years. However, the received signals are subjected to various urban channel impairments, like shadowing and multipath fading. Therefore, the decoding performance is different from that in open-sky conditions. In this paper, a two-state Land Mobile Satellite (LMS) channel based on the Markov process is used to model the urban channel properties, and then, the analysis of decoding performance in terms of frame error rate (FER) in the LMS channel is performed by evaluating the effect of three major influencing factors, specifically, coding and interleaving in the GNSS message, terminal speed, and satellite elevation angle. Extensive simulations are conducted on BDS-3 B1C B-CNAV1 message and GALILEO E5a F/NAV message. The results validate the excellent error correcting performance of the nonbinary low density parity check (NB-LDPC) code of the B-CNAV1 message and the effectiveness of interleaving in both of the messages in urban condition. Furthermore, it also shows that decoding performance improvement can be achieved with higher terminal speed and higher elevation angle in urban scenarios.

Characteristics Analysis of Raw Multi-GNSS Measurement from Xiaomi Mi 8 and Positioning Performance Improvement with L5/E5 Frequency in an Urban Environment

2020 ◽  
Vol 12 (4) ◽  
pp. 744 ◽  
Author(s):  
Lei Guo ◽  
Fuhong Wang ◽  
Jizhang Sang ◽  
Xiaohu Lin ◽  
Xuewen Gong ◽  
...  
Keyword(s):  
High Precision ◽  
Carrier Phase ◽  
Satellite System ◽  
State Equation ◽  
Urban Environments ◽  
Dual Frequency ◽  
Positioning Errors ◽  
Characteristics Analysis ◽  
Pseudorange Noise ◽  
Global Navigation Satellite

Achieving continuous and high-precision positioning services via smartphone under a Global Navigation Satellite System (GNSS)-degraded environment is urgently demanded by the mass market. In 2018, Xiaomi launched the world’s first dual-frequency GNSS smartphone, Xiaomi Mi 8. The newly added L5/E5 signals are more precise and less prone to distortions from multipath reflections. This paper discusses the characteristics of raw dual-frequency GNSS observations from Xiaomi Mi 8 in urban environments; they are characterized by high pseudorange noise and frequent signal interruption. The traditional dual-frequency ionosphere-free combination is not suitable for Xiaomi Mi 8 raw GNSS data processing, since the noise of the combined measurements is much larger than the influence of the ionospheric delay. Therefore, in order to reasonably utilize the high precision carrier phase observations, a time differenced positioning filter is presented in this paper to deliver continuous and smooth navigation results in urban environments. The filter first estimates the inter-epoch position variation (IEPV) with time differenced uncombined L1/E1 and L5/E5 carrier phase observations and constructs the state equation with IEPV to accurately describe the user’s movement. Secondly, the observation equations are formed with uncombined L1/E1 and L5/E5 pseudorange observations. Then, kinematic experiments in open-sky and GNSS-degraded environments are carried out, and the proposed filter is assessed in terms of the positioning accuracy and solution availability. The result in an open-sky environment shows that, assisted with L5/E5 observations, the root mean square (RMS) of the stand-alone horizontal and vertical positioning errors are about 1.22 m and 1.94 m, respectively, with a 97.8% navigation availability. Encouragingly, even in a GNSS-degraded environment, smooth navigation services with accuracies of 1.61 m and 2.16 m in the horizontal and vertical directions are obtained by using multi-GNSS and L5/E5 observations.

Relationships

2018 ◽  
Author(s):  
Philip James
Keyword(s):  
Urban Environment ◽  
Companion Animals ◽  
Domestic Animals ◽  
Urban Environments ◽  
Select Group ◽  
Exotic Pets

Relationships between organisms within urban environments are many and varied. Plants are found in many households, and in addition to the benefits derived from their decorative properties, they also purify the air by removing pollutants. Over the course of history some animals have become domesticated: cows, horses, goats, providing food and transport. Of these, a select group have become companions (cats, dogs, and more exotic pets). Such domesticated and companion animals are an important part of the overall biology of urban environments and these relationships are explored and discussed. Some former companion or domestic animals have become feral, and other animals have never been domesticated and live freely in the urban environment. Some of these animals have beneficial relationships with humans whereas others are parasitic or are considered pests. These relationships are the focus for the later part of the exploration set out in this chapter.

What is the urban environment and what is biology?

2018 ◽  
Author(s):  
Philip James
Keyword(s):  
Urban Environment ◽  
Urban Environments ◽  
First Century ◽  
Final Part ◽  
Global Spread ◽  
Twenty First Century ◽  
Genes To Ecosystems ◽  
Micro Organisms ◽  
Initial Focus

The two main themes contained within the title The Biology of Urban Environments are explored. The initial focus is on urban environments. A discussion of the origins of cities and the global spread of urbanization leads on to a consideration of urban environments in the twenty-first century. In the second section, the focus switches to biology. The scope of the discipline is set out in terms of both the range of sub-disciplines and of biological scales. It is established from this discussion that in this book the topics considered span from genes to ecosystems and will be illustrated by examples of the biology of micro-organisms, plants, and animals. Importantly humans will be included within this consideration: our biology is affected by urban environments. The final part presents the structure of the book.

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