Pub Date : 2023-04-24DOI: 10.1109/PLANS53410.2023.10140116
F. Causa, G. Fasano
This paper uses multi-UAV cooperation to enhance the positioning performance of a swarm when GNSS measurements are affected by faults. Only pseudorange observables are accounted for and a centralized extended Kalman filter, which can deal with both cooperative and non cooperative measurements, has been developed. The filter is complemented with a fault detection and elimination strategy based on Mahalanobis distance, which removes pseudoranges that are deemed faulty. Contribution of relative sensing sources (camera or ranging devices) and formation geometry to cooperative GNSS integrity mitigation is investigated, and the concept of cooperative slope is introduced as a metric to define the best cooperative formation geometry. Results demonstrate, by simulating spoofing and multipath phenomena, that cooperation enhances the navigation performance of the UAVs in a multi vehicle formation only if the formation geometry is correctly selected with the aid of the cooperative slope metric.
{"title":"Multi-drone cooperation to improve navigation integrity in low altitude urban environments","authors":"F. Causa, G. Fasano","doi":"10.1109/PLANS53410.2023.10140116","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140116","url":null,"abstract":"This paper uses multi-UAV cooperation to enhance the positioning performance of a swarm when GNSS measurements are affected by faults. Only pseudorange observables are accounted for and a centralized extended Kalman filter, which can deal with both cooperative and non cooperative measurements, has been developed. The filter is complemented with a fault detection and elimination strategy based on Mahalanobis distance, which removes pseudoranges that are deemed faulty. Contribution of relative sensing sources (camera or ranging devices) and formation geometry to cooperative GNSS integrity mitigation is investigated, and the concept of cooperative slope is introduced as a metric to define the best cooperative formation geometry. Results demonstrate, by simulating spoofing and multipath phenomena, that cooperation enhances the navigation performance of the UAVs in a multi vehicle formation only if the formation geometry is correctly selected with the aid of the cooperative slope metric.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134109886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-24DOI: 10.1109/PLANS53410.2023.10139965
R. Chrabieh, Nathan Arbeid
We present a Maximum Likelihood code phase discriminator for GNSS. In the absence of overlapping multipath, it optimizes the interpolation of a few correlators to locate the peak of the correlation, i.e., the time of arrival of the signal. A key point is that noise whitening is applied post-correlation. We show how it outperforms classical code phase discriminators in terms of converging to an accurate TOA, for both the coherent and non-coherent cases, at high or low SNR. For the non-coherent correlators, we show the benefit of computing the correlators covariance matrix. The discriminator can use any set of correlators having any spacings, and it can account for time drifting correlators and for PRN auto-correlation distortions. A benefit is improved responsiveness to satellite tracking in difficult environments. Faster convergence to the solution enables efficient software implementations and reduced power consumption. The ML discriminator is particularly suitable for computationally intensive wide band systems such as GPS L5, or for terrestrial beacon systems such as TerraPoiNT, 4G or 5G.
{"title":"Maximum Likelihood Code Phase Discriminator for GNSS","authors":"R. Chrabieh, Nathan Arbeid","doi":"10.1109/PLANS53410.2023.10139965","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10139965","url":null,"abstract":"We present a Maximum Likelihood code phase discriminator for GNSS. In the absence of overlapping multipath, it optimizes the interpolation of a few correlators to locate the peak of the correlation, i.e., the time of arrival of the signal. A key point is that noise whitening is applied post-correlation. We show how it outperforms classical code phase discriminators in terms of converging to an accurate TOA, for both the coherent and non-coherent cases, at high or low SNR. For the non-coherent correlators, we show the benefit of computing the correlators covariance matrix. The discriminator can use any set of correlators having any spacings, and it can account for time drifting correlators and for PRN auto-correlation distortions. A benefit is improved responsiveness to satellite tracking in difficult environments. Faster convergence to the solution enables efficient software implementations and reduced power consumption. The ML discriminator is particularly suitable for computationally intensive wide band systems such as GPS L5, or for terrestrial beacon systems such as TerraPoiNT, 4G or 5G.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134165754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-24DOI: 10.1109/PLANS53410.2023.10139944
H. K. Dureppagari, Don-Roberts Emenonye, Harpreet S. Dhillon, R. Buehrer
Unmanned aerial vehicle (UAV) aided communication systems have been gaining attention due to their wide applications in public service, military sectors, and emergency services as well as their flexibility in deployment. In this paper, we propose using 5G positioning techniques and collaborative localization to accurately estimate the locations of first responders located inside the building using outdoor UAV-mounted base stations (BSs) serving as anchors. For this setup, we perform a comprehensive Cramér-Ran lower bound (CRLB) based analysis to evaluate the performance of position estimation in 3D and to examine the sensitivity of the localization performance to different system parameters. Our analysis considers various system parameters: dynamic line-of-sight (LOS)/non-line-of-sight (NLOS) characteristics of the channel, geometry of the anchors, number of anchors, number of LOS anchors, NLOS bias between an anchor and a target node, and between target nodes, anchor location uncertainty, and synchronization errors among anchors. Our analysis uses time-difference-of-arrival (TDOA), and time-of-arrival (TOA) based positioning methods assuming both LOS and NLOS propagation. Through our analysis, we identify the system parameters that most significantly impact the localization performance as well as the scenarios that provide location accuracy or position error bound (PEB) on the order of 2m and 3m.
{"title":"UAV-Aided Indoor Localization of Emergency Response Personnel","authors":"H. K. Dureppagari, Don-Roberts Emenonye, Harpreet S. Dhillon, R. Buehrer","doi":"10.1109/PLANS53410.2023.10139944","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10139944","url":null,"abstract":"Unmanned aerial vehicle (UAV) aided communication systems have been gaining attention due to their wide applications in public service, military sectors, and emergency services as well as their flexibility in deployment. In this paper, we propose using 5G positioning techniques and collaborative localization to accurately estimate the locations of first responders located inside the building using outdoor UAV-mounted base stations (BSs) serving as anchors. For this setup, we perform a comprehensive Cramér-Ran lower bound (CRLB) based analysis to evaluate the performance of position estimation in 3D and to examine the sensitivity of the localization performance to different system parameters. Our analysis considers various system parameters: dynamic line-of-sight (LOS)/non-line-of-sight (NLOS) characteristics of the channel, geometry of the anchors, number of anchors, number of LOS anchors, NLOS bias between an anchor and a target node, and between target nodes, anchor location uncertainty, and synchronization errors among anchors. Our analysis uses time-difference-of-arrival (TDOA), and time-of-arrival (TOA) based positioning methods assuming both LOS and NLOS propagation. Through our analysis, we identify the system parameters that most significantly impact the localization performance as well as the scenarios that provide location accuracy or position error bound (PEB) on the order of 2m and 3m.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134246121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-24DOI: 10.1109/PLANS53410.2023.10140119
K. Mimouni, Odile Maliet, Julie Antic
The aviation Minimum Operational Performance Standard defines the SBAS protection levels as the product of the estimated standard deviation of the positioning error and a scaling factor called K-factor. The K-factor depends on the time window of interest and on the correlation between errors in the time window. The K-factors defined in aviation are difficult to generalize to other specifications in other domains, such as rail and maritime applications. This article presents a simple formula to calculate the K-factor for any value of integrity risk and time interval. The resulting K-factor is shown to be mathematically rigorous under the hypothesis of Gaussian error distribution but without any assumption on the correlation structure of the successive position estimates. The Gaussian assumption can be relaxed and replaced by overbounding with a Gaussian distribution with a very good approximation. This formula can be used in any GNSS application where integrity is needed.
{"title":"A simple and robust K-factor computation method for GNSS integrity needs","authors":"K. Mimouni, Odile Maliet, Julie Antic","doi":"10.1109/PLANS53410.2023.10140119","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140119","url":null,"abstract":"The aviation Minimum Operational Performance Standard defines the SBAS protection levels as the product of the estimated standard deviation of the positioning error and a scaling factor called K-factor. The K-factor depends on the time window of interest and on the correlation between errors in the time window. The K-factors defined in aviation are difficult to generalize to other specifications in other domains, such as rail and maritime applications. This article presents a simple formula to calculate the K-factor for any value of integrity risk and time interval. The resulting K-factor is shown to be mathematically rigorous under the hypothesis of Gaussian error distribution but without any assumption on the correlation structure of the successive position estimates. The Gaussian assumption can be relaxed and replaced by overbounding with a Gaussian distribution with a very good approximation. This formula can be used in any GNSS application where integrity is needed.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129191227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-24DOI: 10.1109/PLANS53410.2023.10140090
Xiao Hu, Xiaochuan Gong, Xiaolong Ji, Chao Wei, Hann Lam Woo, Firdaus Kiagos, Yanjin Li, Chunda Ding, Minbo Qiu, Bo Hu
Grab is Southeast Asia's leading superapp that provides everyday services like Deliveries, Mobility, Financial Services, and more. Location information is the backbone of our services, hence poor GNSS quality hurts our users' experience, especially our driver partners. The objective of this work is to explore the possibility of achieving precise positioning by implementing RTK/DGNSS on Android smartphones. In this contribution, we proposed a new service structure and pipeline to upload the GNSS raw measurements from the phone to the back end, the algorithm can support multiple users to conduct the RTK/DGNSS calculation concurrently. Road tests in different environments were conducted to evaluate the performance of our proposed methodology, and a study on the comparison between native mobile phone location output and our positioning service was done. The results show that in open sky scenarios, our algorithm performs much better than the native Android location, which confirms the interest of using the RTK/DGNSS to improve the positioning accuracy on Android devices for real business usage.
{"title":"Implementation of real-time RTK/DGNSS on smartphones and positioning improvement for millions of users in Southeast Asia","authors":"Xiao Hu, Xiaochuan Gong, Xiaolong Ji, Chao Wei, Hann Lam Woo, Firdaus Kiagos, Yanjin Li, Chunda Ding, Minbo Qiu, Bo Hu","doi":"10.1109/PLANS53410.2023.10140090","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140090","url":null,"abstract":"Grab is Southeast Asia's leading superapp that provides everyday services like Deliveries, Mobility, Financial Services, and more. Location information is the backbone of our services, hence poor GNSS quality hurts our users' experience, especially our driver partners. The objective of this work is to explore the possibility of achieving precise positioning by implementing RTK/DGNSS on Android smartphones. In this contribution, we proposed a new service structure and pipeline to upload the GNSS raw measurements from the phone to the back end, the algorithm can support multiple users to conduct the RTK/DGNSS calculation concurrently. Road tests in different environments were conducted to evaluate the performance of our proposed methodology, and a study on the comparison between native mobile phone location output and our positioning service was done. The results show that in open sky scenarios, our algorithm performs much better than the native Android location, which confirms the interest of using the RTK/DGNSS to improve the positioning accuracy on Android devices for real business usage.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128487912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-24DOI: 10.1109/PLANS53410.2023.10139994
H. Wassaf, J. Rife, K. V. Dyke
Automated Driving Systems (ADS) are expected to be an integral component of a future safe and efficient intelligent transportation system. ADSs assume strategic and tactical maneuvering decisions, and associated vehicle control functions traditionally performed by human drivers. Navigation systems supporting this high level of automation are safety critical and must meet requirements imposed by the use-case nominal operation conditions. These systems must also be resilient to certain intentional and unintentional threats encountered during operation. While there have been past and ongoing efforts to determine PNT safety performance needs, an approach to quantify navigation system resiliency to intentional threats is still lacking. In this paper we develop such approach and introduce two resiliency metrics to quantitatively assess automated vehicle performance, with a primary focus on ADS with SAE Automation Level 4 (L4). Our resiliency metrics build on formal definitions of integrity, accuracy, availability, and continuity, adapting concepts used in commercial aviation to also apply to road applications. In our analysis, the key is to distinguish faults (for which a prior probability can be defined) from threats (for which a prior cannot be defined). A simulation of an ADS L4 multilane highway application with vehicle-to-vehicle and vehicle-to-infrastructure communication quantitatively demonstrates how our proposed approach allows for safe operation during a time-limited transition immediately after the introduction of a threat and also for persistent threats (via reduced capacity mitigation). This simulation will also illustrate how, for a particular navigation system, the two complementary resiliency metrics can be used to quantify the increased risk during the time-limited transition as well as the capacity degradation level for safe steady state safe operations.
{"title":"Resiliency Characterization of Navigation Systems for Intelligent Transportation Applications","authors":"H. Wassaf, J. Rife, K. V. Dyke","doi":"10.1109/PLANS53410.2023.10139994","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10139994","url":null,"abstract":"Automated Driving Systems (ADS) are expected to be an integral component of a future safe and efficient intelligent transportation system. ADSs assume strategic and tactical maneuvering decisions, and associated vehicle control functions traditionally performed by human drivers. Navigation systems supporting this high level of automation are safety critical and must meet requirements imposed by the use-case nominal operation conditions. These systems must also be resilient to certain intentional and unintentional threats encountered during operation. While there have been past and ongoing efforts to determine PNT safety performance needs, an approach to quantify navigation system resiliency to intentional threats is still lacking. In this paper we develop such approach and introduce two resiliency metrics to quantitatively assess automated vehicle performance, with a primary focus on ADS with SAE Automation Level 4 (L4). Our resiliency metrics build on formal definitions of integrity, accuracy, availability, and continuity, adapting concepts used in commercial aviation to also apply to road applications. In our analysis, the key is to distinguish faults (for which a prior probability can be defined) from threats (for which a prior cannot be defined). A simulation of an ADS L4 multilane highway application with vehicle-to-vehicle and vehicle-to-infrastructure communication quantitatively demonstrates how our proposed approach allows for safe operation during a time-limited transition immediately after the introduction of a threat and also for persistent threats (via reduced capacity mitigation). This simulation will also illustrate how, for a particular navigation system, the two complementary resiliency metrics can be used to quantify the increased risk during the time-limited transition as well as the capacity degradation level for safe steady state safe operations.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129171121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-24DOI: 10.1109/PLANS53410.2023.10140094
Tobias Müller, Sebastian Durst, Pascal Marquardt, S. Brüggenwirth
In hostile environments, GNSS is a potentially unreliable solution for self-localization and navigation. Many systems only use an IMU as a backup system, resulting in integration errors which can dramatically increase during mission execution. We suggest using a fighter radar to illuminate satellites with known trajectories to enhance the self-localization information. This technique is time-consuming and resource-demanding but necessary as other tasks depend on the self-localization accuracy. Therefore an adaption of classical resource management frameworks is required. We propose a quality of service based resource manager with capabilities to account for inter-task dependencies to optimize the self-localization update strategy. Our results show that this leads to adaptive navigation update strategies, mastering the trade-off between self-localization and the requirements of other tasks.
{"title":"Quality of Service Based Radar Resource Management for Navigation and Positioning","authors":"Tobias Müller, Sebastian Durst, Pascal Marquardt, S. Brüggenwirth","doi":"10.1109/PLANS53410.2023.10140094","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140094","url":null,"abstract":"In hostile environments, GNSS is a potentially unreliable solution for self-localization and navigation. Many systems only use an IMU as a backup system, resulting in integration errors which can dramatically increase during mission execution. We suggest using a fighter radar to illuminate satellites with known trajectories to enhance the self-localization information. This technique is time-consuming and resource-demanding but necessary as other tasks depend on the self-localization accuracy. Therefore an adaption of classical resource management frameworks is required. We propose a quality of service based resource manager with capabilities to account for inter-task dependencies to optimize the self-localization update strategy. Our results show that this leads to adaptive navigation update strategies, mastering the trade-off between self-localization and the requirements of other tasks.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117082100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-24DOI: 10.1109/PLANS53410.2023.10139995
Chengming Jin, Wee Peng Tay, K. Zhao, Keck Voon Ling, Jun Lu, Yue Wang
Apart from communications, the Fifth Generation (5G) technology is also motivated by positioning requirements down to the sub-meter level across industry verticals. In this work, we utilize Universal Software Radio Peripheral to transmit and receive the 5G New Radio signals. The obtained samples are then processed by the proposed 5G code and carrier phase software defined receiver. In this process, the dedicated 5G Positioning Reference Signal (PRS) is adopted to obtain time of arrival estimates using more accurate carrier phase measure-ments instead of code phase measurements. The continuously transmitted 5G PRSs over time enable accurate carrier phase tracking and avoid ambiguity problems during the tracking stage in line-of-sight environments. Furthermore, a roadside unit is set up to observe the same signals and cancel out the measurement error introduced by the clock offset between two transmitters. Finally, some field experiments are carried out, and the experimental results indicate that using 5G double-difference carrier phase measurements from only four transmitters, a position root mean square error of 0.790m is achievable.
{"title":"A Sub-meter Accurate Positioning using 5G Double-difference Carrier Phase Measurements","authors":"Chengming Jin, Wee Peng Tay, K. Zhao, Keck Voon Ling, Jun Lu, Yue Wang","doi":"10.1109/PLANS53410.2023.10139995","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10139995","url":null,"abstract":"Apart from communications, the Fifth Generation (5G) technology is also motivated by positioning requirements down to the sub-meter level across industry verticals. In this work, we utilize Universal Software Radio Peripheral to transmit and receive the 5G New Radio signals. The obtained samples are then processed by the proposed 5G code and carrier phase software defined receiver. In this process, the dedicated 5G Positioning Reference Signal (PRS) is adopted to obtain time of arrival estimates using more accurate carrier phase measure-ments instead of code phase measurements. The continuously transmitted 5G PRSs over time enable accurate carrier phase tracking and avoid ambiguity problems during the tracking stage in line-of-sight environments. Furthermore, a roadside unit is set up to observe the same signals and cancel out the measurement error introduced by the clock offset between two transmitters. Finally, some field experiments are carried out, and the experimental results indicate that using 5G double-difference carrier phase measurements from only four transmitters, a position root mean square error of 0.790m is achievable.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117158681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-24DOI: 10.1109/PLANS53410.2023.10140113
Xin Qi, Bing Xu
Multipath is a major error source for global navigation satellite systems (GNSS) positioning, which is hard to be eliminated. This paper develops a machine learning (ML) assisted multipath signal parameter estimation to mitigate multipath interference. In this work, random forest (RF) is employed to operate on multiple samples with equal chip spacing of the autocorrelation function to obtain amplitude and code phase delay estimates of multipath. The direct-path signal is then restored by removing the estimated multipath components from the total received signal. The RF-based multipath estimation method is evaluated in one multipath scenario under weak signal environments with multipath estimation delay lock loop (MEDLL) as the benchmark. The simulation results show that the RF-based estimator has better parameter estimation and multipath mitigation performances than MEDLL in weak signal environments. It is also found that the proposed multipath signal parameter estimator performs well with limited number of correlators, demonstrating its feasibility.
{"title":"Machine learning assisted multipath signal parameter estimation and its evaluation under weak signal environment","authors":"Xin Qi, Bing Xu","doi":"10.1109/PLANS53410.2023.10140113","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140113","url":null,"abstract":"Multipath is a major error source for global navigation satellite systems (GNSS) positioning, which is hard to be eliminated. This paper develops a machine learning (ML) assisted multipath signal parameter estimation to mitigate multipath interference. In this work, random forest (RF) is employed to operate on multiple samples with equal chip spacing of the autocorrelation function to obtain amplitude and code phase delay estimates of multipath. The direct-path signal is then restored by removing the estimated multipath components from the total received signal. The RF-based multipath estimation method is evaluated in one multipath scenario under weak signal environments with multipath estimation delay lock loop (MEDLL) as the benchmark. The simulation results show that the RF-based estimator has better parameter estimation and multipath mitigation performances than MEDLL in weak signal environments. It is also found that the proposed multipath signal parameter estimator performs well with limited number of correlators, demonstrating its feasibility.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115271496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-24DOI: 10.1109/PLANS53410.2023.10140058
Zachary Clements, T. Humphreys, P. Ellis
This paper explores two-step and direct geolocation of terrestrial Global Navigation Satellite System (GNSS) jammers from Low Earth Orbit (LEO). Within the past decade, there has been a sharp increase in GNSS outages due to deliberate GNSS jamming. Receivers in LEO are uniquely situated to detect, classify, and geolocate terrestrial GNSS jammers. The conventional two-step geolocation method first estimates the differential delay and differential Doppler, then uses a time history of these to estimate the transmitter location. By contrast, direct geolocation is a single-step search over a geographical grid that enables estimation of the transmitter location directly from the observed signals. Signals from narrowband, matched-code, and chirp jammers recently captured in the GNSS frequency bands by two time-synchronized LEO receivers over the Eastern Mediterranean are analyzed and the emitters geolocated. It is demonstrated that the direct approach is effective even for low signal-to-noise ratio interference signals based on short captures with multiple emitters. Moreover, the direct approach enables geolocation of multiple emitters with cyclostationary signals (e.g., chirp jammers), whereas the two-step method struggles in such cases to associate emitters with their corresponding structures in differential delay and Doppler space.
{"title":"Dual-Satellite Geolocation of Terrestrial GNSS Jammers from Low Earth Orbit","authors":"Zachary Clements, T. Humphreys, P. Ellis","doi":"10.1109/PLANS53410.2023.10140058","DOIUrl":"https://doi.org/10.1109/PLANS53410.2023.10140058","url":null,"abstract":"This paper explores two-step and direct geolocation of terrestrial Global Navigation Satellite System (GNSS) jammers from Low Earth Orbit (LEO). Within the past decade, there has been a sharp increase in GNSS outages due to deliberate GNSS jamming. Receivers in LEO are uniquely situated to detect, classify, and geolocate terrestrial GNSS jammers. The conventional two-step geolocation method first estimates the differential delay and differential Doppler, then uses a time history of these to estimate the transmitter location. By contrast, direct geolocation is a single-step search over a geographical grid that enables estimation of the transmitter location directly from the observed signals. Signals from narrowband, matched-code, and chirp jammers recently captured in the GNSS frequency bands by two time-synchronized LEO receivers over the Eastern Mediterranean are analyzed and the emitters geolocated. It is demonstrated that the direct approach is effective even for low signal-to-noise ratio interference signals based on short captures with multiple emitters. Moreover, the direct approach enables geolocation of multiple emitters with cyclostationary signals (e.g., chirp jammers), whereas the two-step method struggles in such cases to associate emitters with their corresponding structures in differential delay and Doppler space.","PeriodicalId":344794,"journal":{"name":"2023 IEEE/ION Position, Location and Navigation Symposium (PLANS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115288482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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