Pub Date : 2010-05-04DOI: 10.1109/PLANS.2010.5507202
M. Bahrami, M. Ziebart
Instantaneous Real-Time Kinematic (RTK) is one of the most precise GNSS positioning and navigation technologies, with which users can obtain centimeter-level relative positioning accuracy in real-time. This technique relies fundamentally upon the inversion of both carrier-phase and code pseudoranges and successful instantaneous ambiguity resolution. However, in this approach the probability of fixing ambiguities to correct integer values is dominated by the relatively imprecise code pseudorange measurements especially in urban areas and difficult environments where the level of noise and multipath on code pseudoranges are high. This problem may be overcome partially by carrier-smoothing of the code pseudoranges using e.g. the Hatch filter. However, in unfavorable environments frequent carrier-phase outages, cycle slips and anomalies occur due to blockages and foliage, etc. and hence the effectiveness of the conventional carrier-smoothing of the code pseudoranges is limited. On the other hand, a receiver can generate continuous Doppler frequency shift measurements with centimeter-level precision even in severe urban canyons as long as signals are present. The objective of this paper is to show the advantage of adding Doppler frequency shift information to instantaneous RTK positioning and navigation in particular for single frequency users. The aim is to enhance the probability of identifying the correct set of integer ambiguities and hence increase the success rate of the integer ambiguity resolution process in instantaneous RTK. In this paper, a simple combination procedure of the noisy code-based pseudorange measurements and the centimeter-level precision receiver-generated Doppler measurements is used to smooth the code pseudoranges. Doppler-smoothed code pseudoranges are then used to help resolve integer ambiguities in the conventional LAMBDA ambiguity resolution method. Single-epoch single-frequency static trials over varying baselines from few meters up to 40 kilometers have shown improvement in fixing the correct set of integer ambiguity vectors when Doppler-smoothed pseudoranges are used compared to the conventional ambiguity resolution without Doppler-aiding. Relative kinematic positioning with single frequency mass market receivers in urban areas using Virtual Reference Stations (VRS) has also shown improvement.
{"title":"Instantaneous Doppler-aided RTK positioning with single frequency receivers","authors":"M. Bahrami, M. Ziebart","doi":"10.1109/PLANS.2010.5507202","DOIUrl":"https://doi.org/10.1109/PLANS.2010.5507202","url":null,"abstract":"Instantaneous Real-Time Kinematic (RTK) is one of the most precise GNSS positioning and navigation technologies, with which users can obtain centimeter-level relative positioning accuracy in real-time. This technique relies fundamentally upon the inversion of both carrier-phase and code pseudoranges and successful instantaneous ambiguity resolution. However, in this approach the probability of fixing ambiguities to correct integer values is dominated by the relatively imprecise code pseudorange measurements especially in urban areas and difficult environments where the level of noise and multipath on code pseudoranges are high. This problem may be overcome partially by carrier-smoothing of the code pseudoranges using e.g. the Hatch filter. However, in unfavorable environments frequent carrier-phase outages, cycle slips and anomalies occur due to blockages and foliage, etc. and hence the effectiveness of the conventional carrier-smoothing of the code pseudoranges is limited. On the other hand, a receiver can generate continuous Doppler frequency shift measurements with centimeter-level precision even in severe urban canyons as long as signals are present. The objective of this paper is to show the advantage of adding Doppler frequency shift information to instantaneous RTK positioning and navigation in particular for single frequency users. The aim is to enhance the probability of identifying the correct set of integer ambiguities and hence increase the success rate of the integer ambiguity resolution process in instantaneous RTK. In this paper, a simple combination procedure of the noisy code-based pseudorange measurements and the centimeter-level precision receiver-generated Doppler measurements is used to smooth the code pseudoranges. Doppler-smoothed code pseudoranges are then used to help resolve integer ambiguities in the conventional LAMBDA ambiguity resolution method. Single-epoch single-frequency static trials over varying baselines from few meters up to 40 kilometers have shown improvement in fixing the correct set of integer ambiguity vectors when Doppler-smoothed pseudoranges are used compared to the conventional ambiguity resolution without Doppler-aiding. Relative kinematic positioning with single frequency mass market receivers in urban areas using Virtual Reference Stations (VRS) has also shown improvement.","PeriodicalId":94036,"journal":{"name":"IEEE/ION Position Location and Navigation Symposium : [proceedings]. IEEE/ION Position Location and Navigation Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81585031","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 : 2010-05-04DOI: 10.1109/PLANS.2010.5507189
Yongjun Yu, Jianye Liu, Zhi Xiong, Rongbing Li
Multi-sensors combination is an effective means to improve the accuracy and fault tolerance of the navigation system for UAVs with long range and high altitude. Based on analyses of attitude determination using STAR sensor, this paper presents a SINS/STAR/GPS information fusion navigation system. To solve the problem of the incoordinate interval characteristics of multi-sensors, an asynchronous centralized Kalman Filter (AKF) is designed., and the filter period is divided to time update period and measurement update period. An extrapolation method is designed to deal with GPS information. Moreover, a new model is designed to solve the problem of attitude combination in process of vertical mobility. Simulation results indicate that filtering accuracy is improved by 50% with the Kalman Filter, and the method is of important value in engineering application
{"title":"Research on multi-sensor information fusion system application for UAVS with long range and high altitude","authors":"Yongjun Yu, Jianye Liu, Zhi Xiong, Rongbing Li","doi":"10.1109/PLANS.2010.5507189","DOIUrl":"https://doi.org/10.1109/PLANS.2010.5507189","url":null,"abstract":"Multi-sensors combination is an effective means to improve the accuracy and fault tolerance of the navigation system for UAVs with long range and high altitude. Based on analyses of attitude determination using STAR sensor, this paper presents a SINS/STAR/GPS information fusion navigation system. To solve the problem of the incoordinate interval characteristics of multi-sensors, an asynchronous centralized Kalman Filter (AKF) is designed., and the filter period is divided to time update period and measurement update period. An extrapolation method is designed to deal with GPS information. Moreover, a new model is designed to solve the problem of attitude combination in process of vertical mobility. Simulation results indicate that filtering accuracy is improved by 50% with the Kalman Filter, and the method is of important value in engineering application","PeriodicalId":94036,"journal":{"name":"IEEE/ION Position Location and Navigation Symposium : [proceedings]. IEEE/ION Position Location and Navigation Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73084115","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 : 2010-05-04DOI: 10.1109/PLANS.2010.5507306
Zexi Liu, Chang-Hee Won
We perform personal navigation using inertial sensors at knee, waist and foot positions. We found out that the knee attached gyroscope gives the best distance traveled information. The proposed system at the knee takes advantage of the fact that the angular displacements repeats at each period (each step of the walking person). Using this period, the system will keep the angular displacement errors bounded. Also, the waist attached gyroscope gives the best heading information. Consequently, we propose a personal navigation system that consists of gyroscopes at the knee and waist. The system performance was evaluated with a number of indoor experiments and the experimental results showed that this configuration provide better position information compared to other configurations. The system performs well even when the person is climbing stairs.
{"title":"Knee and waist attached gyroscopes for personal navigation: Comparison of knee, waist and foot attached inertial sensors","authors":"Zexi Liu, Chang-Hee Won","doi":"10.1109/PLANS.2010.5507306","DOIUrl":"https://doi.org/10.1109/PLANS.2010.5507306","url":null,"abstract":"We perform personal navigation using inertial sensors at knee, waist and foot positions. We found out that the knee attached gyroscope gives the best distance traveled information. The proposed system at the knee takes advantage of the fact that the angular displacements repeats at each period (each step of the walking person). Using this period, the system will keep the angular displacement errors bounded. Also, the waist attached gyroscope gives the best heading information. Consequently, we propose a personal navigation system that consists of gyroscopes at the knee and waist. The system performance was evaluated with a number of indoor experiments and the experimental results showed that this configuration provide better position information compared to other configurations. The system performs well even when the person is climbing stairs.","PeriodicalId":94036,"journal":{"name":"IEEE/ION Position Location and Navigation Symposium : [proceedings]. IEEE/ION Position Location and Navigation Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76512283","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 : 2010-05-04DOI: 10.1109/PLANS.2010.5507177
S. Langel, S. Khanafseh, Fang-Cheng Chan, B. Pervan
Much research has been conducted in the area of tightly coupled GPS/INS, and this work has resulted in a vast array of navigation algorithms. A common theme of these methods is that they operate on low rate GPS ranging measurements of code and carrier phase together with high rate raw inertial measurements, such as specific force and inertial angular velocity. For stand-alone (i.e., non-differential) GPS navigation applications, high data rate INS outputs can be properly accommodated with today's computer processors. For relative (i.e., differential) GPS navigation applications, the optimal analogous solution would be for the mobile user to have access to the reference station's raw inertial measurements along with its own. However, due to communication bandwidth limitations, it is generally not possible to broadcast high data rate inertial navigation data. In response, an alternative tightly-coupled, differential GPS/INS navigation system is developed here using a decentralized Kalman filtering approach, which can operate at manageable broadcast data rates.
{"title":"Tightly coupled GPS/INS integration for differential carrier phase navigation systems using decentralized estimation","authors":"S. Langel, S. Khanafseh, Fang-Cheng Chan, B. Pervan","doi":"10.1109/PLANS.2010.5507177","DOIUrl":"https://doi.org/10.1109/PLANS.2010.5507177","url":null,"abstract":"Much research has been conducted in the area of tightly coupled GPS/INS, and this work has resulted in a vast array of navigation algorithms. A common theme of these methods is that they operate on low rate GPS ranging measurements of code and carrier phase together with high rate raw inertial measurements, such as specific force and inertial angular velocity. For stand-alone (i.e., non-differential) GPS navigation applications, high data rate INS outputs can be properly accommodated with today's computer processors. For relative (i.e., differential) GPS navigation applications, the optimal analogous solution would be for the mobile user to have access to the reference station's raw inertial measurements along with its own. However, due to communication bandwidth limitations, it is generally not possible to broadcast high data rate inertial navigation data. In response, an alternative tightly-coupled, differential GPS/INS navigation system is developed here using a decentralized Kalman filtering approach, which can operate at manageable broadcast data rates.","PeriodicalId":94036,"journal":{"name":"IEEE/ION Position Location and Navigation Symposium : [proceedings]. IEEE/ION Position Location and Navigation Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75513175","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 : 2010-05-04DOI: 10.1109/PLANS.2010.5507342
P. Madonna, S. Viola, Luca Sfarzo
Many studies have been conducted on RAIM to use GNSS navigation systems in those fields where very strict performances are required. In safety-of-life applications, such as aviation, in critical phases of flight such as approach and landing, integrity plays an extremely important role and integrity monitoring functions become necessary. To perform such task many algorithms have been proposed: NIORAIM is one of the most promising. NIORAIM uses non-uniform weights applied to the pseudo-range measurements of satellites involved in the position solution lowering the integrity levels, thus improving integrity availability at the cost of a very slight degradation of accuracy of the position solution.
{"title":"NIORAIM algorithm applied to a multiconstellation GNSS: Analysis of integrity monitoring performances in various phases of flight","authors":"P. Madonna, S. Viola, Luca Sfarzo","doi":"10.1109/PLANS.2010.5507342","DOIUrl":"https://doi.org/10.1109/PLANS.2010.5507342","url":null,"abstract":"Many studies have been conducted on RAIM to use GNSS navigation systems in those fields where very strict performances are required. In safety-of-life applications, such as aviation, in critical phases of flight such as approach and landing, integrity plays an extremely important role and integrity monitoring functions become necessary. To perform such task many algorithms have been proposed: NIORAIM is one of the most promising. NIORAIM uses non-uniform weights applied to the pseudo-range measurements of satellites involved in the position solution lowering the integrity levels, thus improving integrity availability at the cost of a very slight degradation of accuracy of the position solution.","PeriodicalId":94036,"journal":{"name":"IEEE/ION Position Location and Navigation Symposium : [proceedings]. IEEE/ION Position Location and Navigation Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74797500","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 : 2010-05-04DOI: 10.1109/PLANS.2010.5507294
Lin Wu, Jie Ma, J. Tian
In this paper, a self-adaptive unscented Kalman filtering for underwater gravity aided navigation is constructed. It is more accurate and far easier to implement than an extended Kalman filter. Then the novel navigation algorithm based on the self-adaptive unscented Kalman filter is explored. With this method submerged position fixes for autonomous underwater vehicle can be obtained from comparing gravity fields' measurements with gravity maps. Specifically, simulation results show that navigation errors can be reduced more effectively and efficiently by the presented algorithm.
{"title":"A self-adaptive unscented Kalman filtering for underwater gravity aided navigation","authors":"Lin Wu, Jie Ma, J. Tian","doi":"10.1109/PLANS.2010.5507294","DOIUrl":"https://doi.org/10.1109/PLANS.2010.5507294","url":null,"abstract":"In this paper, a self-adaptive unscented Kalman filtering for underwater gravity aided navigation is constructed. It is more accurate and far easier to implement than an extended Kalman filter. Then the novel navigation algorithm based on the self-adaptive unscented Kalman filter is explored. With this method submerged position fixes for autonomous underwater vehicle can be obtained from comparing gravity fields' measurements with gravity maps. Specifically, simulation results show that navigation errors can be reduced more effectively and efficiently by the presented algorithm.","PeriodicalId":94036,"journal":{"name":"IEEE/ION Position Location and Navigation Symposium : [proceedings]. IEEE/ION Position Location and Navigation Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73545237","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 : 2010-05-04DOI: 10.1109/PLANS.2010.5507264
Y. Kou, X. Zhou, Y. Morton, Lei Zhang
The objective of this study is to develop a software receiver to effectively process L2C GPS signals under ionosphere scintillations. Several L2C signal processing algorithms are implemented in a VC++ software receiver with efficient CM signal acquisition, rapid transferring from acquisition to tracking, and robust CL signal tracking. These algorithms are validated using live GPS signals and simulated RF signals. A conventional PLL and a Kalman Filter based PLL (KFPLL) tracking algorithm are implemented and their performances are evaluated using simulated digital IF signals under strong scintillation conditions. Our results show that the receiver estimated S4 index serves as a good indicator of scintillation intensity level even with frequent cycle slips during deep amplitude fading. Appropriate characterization of signal intensity spectrum is only possible with relatively high signal C/N0. The carrier phase scintillation is analyzed in terms of steady state tracking errors, cycle slips, standard deviation of detrended phase errors, as well as detrended carrier phase spectral analysis. Compared to the conventional PLL, the KFPLL has a slower but steadier transient response due to its incorporation of a priori information. Our test results show that the tracking threshold of our L2C software receiver reaches 22dB-Hz in the presence of moderate-level ionosphere scintillations.
{"title":"Processing GPS L2C signals under ionospheric scintillations","authors":"Y. Kou, X. Zhou, Y. Morton, Lei Zhang","doi":"10.1109/PLANS.2010.5507264","DOIUrl":"https://doi.org/10.1109/PLANS.2010.5507264","url":null,"abstract":"The objective of this study is to develop a software receiver to effectively process L2C GPS signals under ionosphere scintillations. Several L2C signal processing algorithms are implemented in a VC++ software receiver with efficient CM signal acquisition, rapid transferring from acquisition to tracking, and robust CL signal tracking. These algorithms are validated using live GPS signals and simulated RF signals. A conventional PLL and a Kalman Filter based PLL (KFPLL) tracking algorithm are implemented and their performances are evaluated using simulated digital IF signals under strong scintillation conditions. Our results show that the receiver estimated S4 index serves as a good indicator of scintillation intensity level even with frequent cycle slips during deep amplitude fading. Appropriate characterization of signal intensity spectrum is only possible with relatively high signal C/N0. The carrier phase scintillation is analyzed in terms of steady state tracking errors, cycle slips, standard deviation of detrended phase errors, as well as detrended carrier phase spectral analysis. Compared to the conventional PLL, the KFPLL has a slower but steadier transient response due to its incorporation of a priori information. Our test results show that the tracking threshold of our L2C software receiver reaches 22dB-Hz in the presence of moderate-level ionosphere scintillations.","PeriodicalId":94036,"journal":{"name":"IEEE/ION Position Location and Navigation Symposium : [proceedings]. IEEE/ION Position Location and Navigation Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75611204","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 : 2010-05-04DOI: 10.1109/PLANS.2010.5507176
R. Zheng, MoHan Chen, X. Ba, Jie Chen
A novel fine code phase determination approach is proposed based on the deduced autocorrelation formula of C/A code for bandlimited receivers. The approach is able to significantly improve the navigation fix accuracy for bandlimited snapshot GPS receivers. A simplified algorithm based on the Taylor expansion of the correlation formula is proposed as well to reduce the computational complexity. In addition, a modified circular correlation combined with frequency FFT acquisition engine optimized for snapshot receivers is proposed, which is suitable for the proposed fine code determination algorithm. It also utilizes a proposed “coarse capture & confirm” mechanism to suppress the correlation peak distortion as well as the false alarm probability. Simulations with data sampled from both simulator and real world show that the proposed approaches are able to significantly improve the positioning accuracy in complex environments such as urban canyons and indoors.
{"title":"A novel fine code phase determination approach for a bandwidth limited snapshot GPS receiver","authors":"R. Zheng, MoHan Chen, X. Ba, Jie Chen","doi":"10.1109/PLANS.2010.5507176","DOIUrl":"https://doi.org/10.1109/PLANS.2010.5507176","url":null,"abstract":"A novel fine code phase determination approach is proposed based on the deduced autocorrelation formula of C/A code for bandlimited receivers. The approach is able to significantly improve the navigation fix accuracy for bandlimited snapshot GPS receivers. A simplified algorithm based on the Taylor expansion of the correlation formula is proposed as well to reduce the computational complexity. In addition, a modified circular correlation combined with frequency FFT acquisition engine optimized for snapshot receivers is proposed, which is suitable for the proposed fine code determination algorithm. It also utilizes a proposed “coarse capture & confirm” mechanism to suppress the correlation peak distortion as well as the false alarm probability. Simulations with data sampled from both simulator and real world show that the proposed approaches are able to significantly improve the positioning accuracy in complex environments such as urban canyons and indoors.","PeriodicalId":94036,"journal":{"name":"IEEE/ION Position Location and Navigation Symposium : [proceedings]. IEEE/ION Position Location and Navigation Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74140861","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 : 2010-05-04DOI: 10.1109/PLANS.2010.5507218
Haochen Tang, S. Pullen, P. Enge, L. Gratton, B. Pervan, M. Brenner, Joe Scheitlin, P. Kline
The Local Area Augmentation System (LAAS) has been developed by the FAA to enable precision approach and landing operations using the Global Positioning System (GPS). Each LAAS installation provides services through a LAAS Ground Facility (LGF) which is located at the airport it serves. By monitoring the GPS signals, measurements, and navigation messages, the LGF is able to exclude unhealthy satellites and broadcast real-time range-correction messages for healthy satellites to users via a VHF data link. Airborne users apply these corrections to remove errors that are common between the LGF and the aircraft. The LGF is also responsible for warning the aircraft of any potential integrity threats that cannot easily be resolved by excluding unhealthy satellites. One source of potential errors is the satellite broadcast ephemeris message, which users decode and use to compute GPS satellite positions. In LAAS, potential GPS ephemeris faults are categorized into two types, A and B, based upon whether or not the fault is associated with a satellite maneuver. This work focuses on aviation navigation threats caused by Type A faults. To detect and mitigate these threats, we investigate two LGF monitors based on comparing expected ranges and range rates (based on broadcast ephemeris) with those measured by the LGF. The effectiveness of these monitors is analyzed and verified in this paper.
{"title":"Ephemeris type a fault analysis and mitigation for LAAS","authors":"Haochen Tang, S. Pullen, P. Enge, L. Gratton, B. Pervan, M. Brenner, Joe Scheitlin, P. Kline","doi":"10.1109/PLANS.2010.5507218","DOIUrl":"https://doi.org/10.1109/PLANS.2010.5507218","url":null,"abstract":"The Local Area Augmentation System (LAAS) has been developed by the FAA to enable precision approach and landing operations using the Global Positioning System (GPS). Each LAAS installation provides services through a LAAS Ground Facility (LGF) which is located at the airport it serves. By monitoring the GPS signals, measurements, and navigation messages, the LGF is able to exclude unhealthy satellites and broadcast real-time range-correction messages for healthy satellites to users via a VHF data link. Airborne users apply these corrections to remove errors that are common between the LGF and the aircraft. The LGF is also responsible for warning the aircraft of any potential integrity threats that cannot easily be resolved by excluding unhealthy satellites. One source of potential errors is the satellite broadcast ephemeris message, which users decode and use to compute GPS satellite positions. In LAAS, potential GPS ephemeris faults are categorized into two types, A and B, based upon whether or not the fault is associated with a satellite maneuver. This work focuses on aviation navigation threats caused by Type A faults. To detect and mitigate these threats, we investigate two LGF monitors based on comparing expected ranges and range rates (based on broadcast ephemeris) with those measured by the LGF. The effectiveness of these monitors is analyzed and verified in this paper.","PeriodicalId":94036,"journal":{"name":"IEEE/ION Position Location and Navigation Symposium : [proceedings]. IEEE/ION Position Location and Navigation Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74732426","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 : 2010-05-04DOI: 10.1109/PLANS.2010.5507265
Ji-Won Park, Seung-Hun Song, T. Sung
In mobile WiMAX, geo-location is possible at the PSS (personal subscriber station) by using the preamble signals broadcasted by all the RAS (Radio Access Station) simultaneously. Using relative arrival times of signals, user location can be obtained by TDoA (Time Difference of Arrival) positioning. However, sufficient number of RAS should be detected to obtain the location in this method. Since mobile WiMAX system employs cellular network structure, the number of RAS that PSS can detect is limited due to low SNR and CCI (co-channel interference) by neighboring RAS. To detect sufficient number of RAS at the PSS, hearability should be enhanced by increasing SNR (signal to noise ratio) and SIR (signal to interference ratio), which can be achieved using long integration and interference cancellation. In multipath environment, however, interference cancellation does not remove the CCI completely. Therefore, multipath mitigation and interference cancellation method should be merged and solved together. In this paper, detection performance after interference cancellation is analyzed using mobile WiMAX geo-location system. Simulation results show that trilateration is possible in most area of the cell coverage after interference cancellation in multipath environment, except at the vicinity of the RAS.
在移动WiMAX中，通过使用所有RAS(无线接入站)同时广播的前置信号，可以在PSS(个人用户站)上进行地理定位。利用信号的相对到达时间，通过TDoA (Time Difference of arrival)定位获得用户位置。然而，在这种方法中，需要检测到足够数量的RAS才能获得位置。由于移动WiMAX系统采用蜂窝网络结构，由于低信噪比和相邻RAS的共信道干扰，PSS能够检测到的RAS数量有限。为了在PSS检测到足够数量的RAS，应该通过提高信噪比(SNR)和信干扰比(SIR)来增强可听性，这可以通过长积分和干扰消除来实现。然而，在多径环境下，干扰消除并不能完全消除CCI。因此，多径抑制和干扰消除方法应该融合在一起解决。本文分析了移动WiMAX地理定位系统在消除干扰后的检测性能。仿真结果表明，在多径环境下，除RAS附近外，干扰消除后的大部分小区都可以实现三边定位。
{"title":"Interference cancellation in multipath environment for mobile WiMAX Geo-location system","authors":"Ji-Won Park, Seung-Hun Song, T. Sung","doi":"10.1109/PLANS.2010.5507265","DOIUrl":"https://doi.org/10.1109/PLANS.2010.5507265","url":null,"abstract":"In mobile WiMAX, geo-location is possible at the PSS (personal subscriber station) by using the preamble signals broadcasted by all the RAS (Radio Access Station) simultaneously. Using relative arrival times of signals, user location can be obtained by TDoA (Time Difference of Arrival) positioning. However, sufficient number of RAS should be detected to obtain the location in this method. Since mobile WiMAX system employs cellular network structure, the number of RAS that PSS can detect is limited due to low SNR and CCI (co-channel interference) by neighboring RAS. To detect sufficient number of RAS at the PSS, hearability should be enhanced by increasing SNR (signal to noise ratio) and SIR (signal to interference ratio), which can be achieved using long integration and interference cancellation. In multipath environment, however, interference cancellation does not remove the CCI completely. Therefore, multipath mitigation and interference cancellation method should be merged and solved together. In this paper, detection performance after interference cancellation is analyzed using mobile WiMAX geo-location system. Simulation results show that trilateration is possible in most area of the cell coverage after interference cancellation in multipath environment, except at the vicinity of the RAS.","PeriodicalId":94036,"journal":{"name":"IEEE/ION Position Location and Navigation Symposium : [proceedings]. IEEE/ION Position Location and Navigation Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77795047","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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