Many applications, including connected and autonomous vehicles, would benefit from navigation technologies that reliably achieve sub-meter position accuracy. Real-time submeter Earth-referenced positioning accuracy has the potential to be achieved with high reliability on moving vehicles by using Global Navigation Satellite Systems (GNSS) if common-mode ranging error correction information is communicated to the vehicles. For successful commercial implementation, such correction information must be delivered on continental or global scales. The communication latency must be small enough to not significantly affect performance. The main focus of the study is to investigate the feasibility to achieve sub-meter positioning accuracy with low-cost GNSS receiver and Inertial Measurement Unit (IMU) sensor. The thesis is divided into two phases based on their common-mode compensation approach. The first phase considers Local Area Differential GNSS (LADGNSS) approach and the second phase investigates Wide Area Differential GNSS (WADGNSS) method.

The first part of this project presents a local differential correction computation methodology designed to be robust to latency and studied position estimation accuracy as a function of differential correction latency for both stationary and moving receivers [121, 122]. This performance was robust to latency up to 600 seconds. Two algorithms incorporated the local differential correction approach defined in [122]. The Position, Velocity, Acceleration (PVA) approach used only DGNSS data with a Kalman filter. The Inertial Navigation System (INS) approach used DGNSS and inertial measurement data within an extended Kalman filter(EKF). The study showed that both approaches achieved performance exceeding the Society of Automotive Engineering (SAE) J2945 specification (1.5 meter horizontal accuracy and 3.0 meter vertical accuracy at 68%) [12] with PVA achieving 1 m horizontal accuracy at 90% and 2 m vertical accuracy at 95% and the INS approach using a consumer-grade IMU achieved 1 m horizontal accuracy at 98% and 2 m vertical accuracy at 95% [125].

The second phase of this project investigates methods for implementing DGNSS corrections on a continental scale, to study the achievable accuracy. The overview includes discussion of WADGNSS, the models that it incorporates, the modeling agencies, and the existing data and model sources. The paper presents a PPP aided INS design and analyzes navigation performance as a function of IMU quality. This paper considers GNSS Precise Point Positioning (PPP) with Least Square (LS), PVA and EKF for static and only EKF for dynamic condition. The experimental results demonstrate positioning accuracy that surpasses the SAE specification using PPP corrected single frequency, single constellation GNSS measurements along with a consumer-grade IMU sensor. Experiments performed in this project (see Section 5.3.2) have demonstrated horizontal position accuracies of 1.35 0.48, 1.19 0.41, and 0.47 0.26 using PPP PVA and demonstrated horizontal position accuracies of 0.81 0.21, 0.52 0.25, and 0.43 0.186 using PPP INS for stationary dataset. Horizontal and vertical position accuracies (see Section 5.3.3) are 0.80 0.40 and 2.32 1.14 with PPP INS respectively for dynamic condition.

This study focuses on single frequency, single constellation results. The availability of multiple constellations and multiple frequencies per constellation will facilitate estimation and compensation of ionospheric error, accommodation of outliers, and accommodation of multipath. It will also greatly increase the number of available measurements and the likelihood that the user has available

a set of satellites with appropriate geometry to reliably achieve the performance specification.

Commercial on-vehicle implementation of Earth-referenced positioning at submeter accuracy with 99% probability wouldrequire widely and reliably available differential corrections; however, such corrections delivered on a nationwide or global scale via satellite systems will incur latency between their time-of-applicability and their time-of-reception at the vehicle.This report summarizes the conclusions of the first phase of work performed by University of California, Riverside (UCR).There were two main goals for this one-year effort.1) To investigate the sensitivity of differential Global Navigation Satellite System (DGNSS) corrections and positionestimation accuracy to communication latency.2) To investigate the feasibility of achieving meter-level positioning accuracy at least 95% of epochs.The first phase of this project was designed to study stationary receivers, to clearly define, demonstrate, and address thechallenging issues. In this study, all algorithms use identical data sets (i.e., measurements and corrections); therefore, the study compares the performance of different algorithms using the same data.

The first conclusion is that GNSS corrections can be designed such that position estimation accuracy is robust to correctionlatency up to 600 seconds. This is demonstrated via experiments that are described in Section VI. The method of GNSS correction calculation is described in Section IV with results of example computations in Appendix A.The second conclusion is that meter-level horizontal position accuracy is achievable in excess of 99% of the samples whena sufficient number of satellites are observable with appropriate geometry, both pseudorange and Doppler measurements areused, and outlier measurements are suitably accommodated. Since DGNSS is designed to remove the effects of common mode errors, this study pays special attention to accommodation of the non-common mode errors. A main issue is accommodating multipath. The importance of the Doppler measurement for addressing multipath is motivated in Section V-B and demonstrated in Fig. 4. Experimental demonstration results are included in Sections VI and VII.Many applications, including connected and autonomous vehicles, would benefit from navigation technologies reliablyachieving sub-meter position accuracy with high reliability for a moving receiver. The second phase of this project willstudy the feasibility of achieving the position accuracy specification for a moving receiver combined with a commercial gradeinertial measurement unit. The results herein used a local base station approach. National or global implementations wouldbe more efficient using networks of base stations working collaboratively to estimate parameters usable by user receivers toreconstruct corrections. Such methods are the focus of phase three of the study.

This report presents experimental results for a moving platform using GPS PPP data for state estimation. Results from two PPP GPS state estimation approaches are presented: point-wise least squares (LS) and aided inertial navigation (INS). The point-wise LS results provide information about the accuracy and reliability of PPP GPS information at each measurement epoch, independent of other epochs. The INS results show the performance that can be achieved by combining information across measurement epochs. INS results are included for two different grades of IMU: navigation grade and consumer grade.

The report cites publications that contain more detailed expla- nations of the GNSS error sources, computation of PPP wide area correction, and the LS and aided INS estimation algorithms.