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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.


Constructed 3D building models in the middle and deep urban canyons. The cyan lines indicate the pedestrian walking trajectories in the dynamic experiments.
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sensors-15-17329-f006: Constructed 3D building models in the middle and deep urban canyons. The cyan lines indicate the pedestrian walking trajectories in the dynamic experiments.

Mentions: This paper selects the Hitotsubashi and Shinjuku area in Tokyo to be the experimental middle and deep urban canyons, respectively. The constructed 3D building models are shown in Figure 6. The single point GPS positioning results, such as weighted least square (WLS), are poor in the two areas. The tests in this paper are performed at two sides of a street and a road intersection. The cut-off angle is 20° in this paper. The data were collected on 5 November 2014, 14 December 2014 and 26 January 2015. The durations of both data are about 210 s. This paper uses a commercial grade receiver, u-blox EVK-M8 GNSS model. The u-blox receiver is set to output pseudorange measurements and positioning result every second. GPS, GLObal NAvigation Satellite System (GLONASS) and QZSS measurements are used in this paper. The quasi ground truth is generated using a topographical method. The video cameras are set in the 18th and 9th floors of a building near the Hitotsubashi and Shinjuku area, respectively, to record the travelled path. The video data output by the cameras are used in combination with one high-resolution aerial photo we bought to get the ground truth data. The aerial photo is 25 cm/pixel and therefore the error distance for each estimate can be calculated. This paper evaluated the lateral positioning error. There are two conventional positioning methods that used for the purpose of comparison. The first one is WLS, and the weighting matrix follows the manual of RTKLIB, which is an open source program [40]. The second one is the WLS using only the LOS visible satellites. The LOS satellites are determined by the ray-tracing results based on the ground truth trajectory. The performance metrics used are the mean and standard deviation of the lateral error and the availability. Availability means the percentage of solutions in a fix period. For example, if a method outputs 80 epochs in a 100 s period, the availability of the method is 80%. Note that the positioning solution will be excluded if its error is larger than 100 m. In addition, the satellite will be excluded if its C/N0 is less than 25 dB-Hz.


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

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

Constructed 3D building models in the middle and deep urban canyons. The cyan lines indicate the pedestrian walking trajectories in the dynamic experiments.
© Copyright Policy
Related In: Results  -  Collection

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

sensors-15-17329-f006: Constructed 3D building models in the middle and deep urban canyons. The cyan lines indicate the pedestrian walking trajectories in the dynamic experiments.
Mentions: This paper selects the Hitotsubashi and Shinjuku area in Tokyo to be the experimental middle and deep urban canyons, respectively. The constructed 3D building models are shown in Figure 6. The single point GPS positioning results, such as weighted least square (WLS), are poor in the two areas. The tests in this paper are performed at two sides of a street and a road intersection. The cut-off angle is 20° in this paper. The data were collected on 5 November 2014, 14 December 2014 and 26 January 2015. The durations of both data are about 210 s. This paper uses a commercial grade receiver, u-blox EVK-M8 GNSS model. The u-blox receiver is set to output pseudorange measurements and positioning result every second. GPS, GLObal NAvigation Satellite System (GLONASS) and QZSS measurements are used in this paper. The quasi ground truth is generated using a topographical method. The video cameras are set in the 18th and 9th floors of a building near the Hitotsubashi and Shinjuku area, respectively, to record the travelled path. The video data output by the cameras are used in combination with one high-resolution aerial photo we bought to get the ground truth data. The aerial photo is 25 cm/pixel and therefore the error distance for each estimate can be calculated. This paper evaluated the lateral positioning error. There are two conventional positioning methods that used for the purpose of comparison. The first one is WLS, and the weighting matrix follows the manual of RTKLIB, which is an open source program [40]. The second one is the WLS using only the LOS visible satellites. The LOS satellites are determined by the ray-tracing results based on the ground truth trajectory. The performance metrics used are the mean and standard deviation of the lateral error and the availability. Availability means the percentage of solutions in a fix period. For example, if a method outputs 80 epochs in a 100 s period, the availability of the method is 80%. Note that the positioning solution will be excluded if its error is larger than 100 m. In addition, the satellite will be excluded if its C/N0 is less than 25 dB-Hz.

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.