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NLOS Correction/Exclusion for GNSS Measurement Using RAIM and City Building Models.

Hsu LT, Gu Y, Kamijo S - Sensors (Basel) (2015)

Bottom Line: The proposed RAIM fault detection and exclusion (FDE) is able to compare the similarity between the raw pseudorange measurement and the simulated pseudorange.Because of the assumption of the single reflection in the ray-tracing technique, an inconsistent case indicates it is a double or multiple reflected NLOS signal.According to the experimental results, the RAIM satellite selection technique can reduce by about 8.4% and 36.2% the positioning solutions with large errors (solutions estimated on the wrong side of the road) for the 3D building model method in the middle and deep urban canyon environment, respectively.

View Article: PubMed Central - PubMed

Affiliation: Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan. qmohsu@kmj.iis.u-tokyo.ac.jp.

ABSTRACT
Currently, global navigation satellite system (GNSS) receivers can provide accurate and reliable positioning service in open-field areas. However, their performance in the downtown areas of cities is still affected by the multipath and none-line-of-sight (NLOS) receptions. This paper proposes a new positioning method using 3D building models and the receiver autonomous integrity monitoring (RAIM) satellite selection method to achieve satisfactory positioning performance in urban area. The 3D building model uses a ray-tracing technique to simulate the line-of-sight (LOS) and NLOS signal travel distance, which is well-known as pseudorange, between the satellite and receiver. The proposed RAIM fault detection and exclusion (FDE) is able to compare the similarity between the raw pseudorange measurement and the simulated pseudorange. The measurement of the satellite will be excluded if the simulated and raw pseudoranges are inconsistent. Because of the assumption of the single reflection in the ray-tracing technique, an inconsistent case indicates it is a double or multiple reflected NLOS signal. According to the experimental results, the RAIM satellite selection technique can reduce by about 8.4% and 36.2% the positioning solutions with large errors (solutions estimated on the wrong side of the road) for the 3D building model method in the middle and deep urban canyon environment, respectively.

No MeSH data available.


Weighting of all the particles of the point 264,239 before (a) and after RAIM (b). The color of the particle indicates the weighting of each particle. Red and blue indicates the highest and lowest weighting, respectively.
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sensors-15-17329-f008: Weighting of all the particles of the point 264,239 before (a) and after RAIM (b). The color of the particle indicates the weighting of each particle. Red and blue indicates the highest and lowest weighting, respectively.

Mentions: To demonstrate the performance improved by the RAIM, we select two typical points in this dynamic data, point 264,038 and 264,239. To observe the left side of Figure 7 (point 264,239), the positioning result before and after applying RAIM is very different. The red ball is much closer to the ground truth than yellow ball. The position solution of the 3D map method is calculated by:(8)x=∑iα(i)P(i)∑iα(i)where x denotes the position estimated, α denotes the weighting of a particle and P denotes the position of a particle. Hence, the weighting of the particles is very essential for the proposed method. Figure 8 shows the weighting of the particle of point 264,239 before and after applying the RAIM. It is obvious that the weighting of the particle behaviors are very different in Figure 8a,b. All of the particles in the left side of Figure 8a are invalid; on the contrary, most of particles in the left side of Figure 8b are valid. Figure 9a,b shows the skyplot and ray-tracing result of point 264,239, respectively. Before applying RAIM technique, the GPS PRN 11 is used in all the particles in the left side. Its simulated pseudorange is assumed to be the single reflection (green line in Figure 9b). However, its pseudorange measurement indicates it is a double reflected NLOS (red line in Figure 9b).


NLOS Correction/Exclusion for GNSS Measurement Using RAIM and City Building Models.

Hsu LT, Gu Y, Kamijo S - Sensors (Basel) (2015)

Weighting of all the particles of the point 264,239 before (a) and after RAIM (b). The color of the particle indicates the weighting of each particle. Red and blue indicates the highest and lowest weighting, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541937&req=5

sensors-15-17329-f008: Weighting of all the particles of the point 264,239 before (a) and after RAIM (b). The color of the particle indicates the weighting of each particle. Red and blue indicates the highest and lowest weighting, respectively.
Mentions: To demonstrate the performance improved by the RAIM, we select two typical points in this dynamic data, point 264,038 and 264,239. To observe the left side of Figure 7 (point 264,239), the positioning result before and after applying RAIM is very different. The red ball is much closer to the ground truth than yellow ball. The position solution of the 3D map method is calculated by:(8)x=∑iα(i)P(i)∑iα(i)where x denotes the position estimated, α denotes the weighting of a particle and P denotes the position of a particle. Hence, the weighting of the particles is very essential for the proposed method. Figure 8 shows the weighting of the particle of point 264,239 before and after applying the RAIM. It is obvious that the weighting of the particle behaviors are very different in Figure 8a,b. All of the particles in the left side of Figure 8a are invalid; on the contrary, most of particles in the left side of Figure 8b are valid. Figure 9a,b shows the skyplot and ray-tracing result of point 264,239, respectively. Before applying RAIM technique, the GPS PRN 11 is used in all the particles in the left side. Its simulated pseudorange is assumed to be the single reflection (green line in Figure 9b). However, its pseudorange measurement indicates it is a double reflected NLOS (red line in Figure 9b).

Bottom Line: The proposed RAIM fault detection and exclusion (FDE) is able to compare the similarity between the raw pseudorange measurement and the simulated pseudorange.Because of the assumption of the single reflection in the ray-tracing technique, an inconsistent case indicates it is a double or multiple reflected NLOS signal.According to the experimental results, the RAIM satellite selection technique can reduce by about 8.4% and 36.2% the positioning solutions with large errors (solutions estimated on the wrong side of the road) for the 3D building model method in the middle and deep urban canyon environment, respectively.

View Article: PubMed Central - PubMed

Affiliation: Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan. qmohsu@kmj.iis.u-tokyo.ac.jp.

ABSTRACT
Currently, global navigation satellite system (GNSS) receivers can provide accurate and reliable positioning service in open-field areas. However, their performance in the downtown areas of cities is still affected by the multipath and none-line-of-sight (NLOS) receptions. This paper proposes a new positioning method using 3D building models and the receiver autonomous integrity monitoring (RAIM) satellite selection method to achieve satisfactory positioning performance in urban area. The 3D building model uses a ray-tracing technique to simulate the line-of-sight (LOS) and NLOS signal travel distance, which is well-known as pseudorange, between the satellite and receiver. The proposed RAIM fault detection and exclusion (FDE) is able to compare the similarity between the raw pseudorange measurement and the simulated pseudorange. The measurement of the satellite will be excluded if the simulated and raw pseudoranges are inconsistent. Because of the assumption of the single reflection in the ray-tracing technique, an inconsistent case indicates it is a double or multiple reflected NLOS signal. According to the experimental results, the RAIM satellite selection technique can reduce by about 8.4% and 36.2% the positioning solutions with large errors (solutions estimated on the wrong side of the road) for the 3D building model method in the middle and deep urban canyon environment, respectively.

No MeSH data available.