A Stand-Alone Approach for High-Sensitivity GNSS Receivers in Signal-Challenged Environment

To navigate in global navigation satellite systems (GNSS) signal-challenged environment, for example, foliage canopy, urban canyon, indoor, etc., high-sensitivity GNSS receivers are usually preferred for the improved acquisition and tracking capabilities. The core of high-sensitivity GNSS receiver design is to extend integration time coherently, which is optimal for improving post-signal-to-noise ratio, mitigating multipath and cross-correlation false locks, and avoiding squaring loss. In GNSS data channels, extending integration time coherently requires the navigation message data bit wipe-off. For stand-alone high-sensitivity GNSS receivers, bit wipe-off is usually achieved by using estimation algorithms (i.e., bit decoding) rather than accessing external networks (i.e., bit aiding). In this paper, the maximum-likelihood (ML) bit decoding is used to estimate the data bit values for bit wipe-off. Furthermore, the benefits of using advanced tracking algorithms—vector tracking and inertial navigation system (INS)-assisted tracking (i.e., ultratight coupling of GNSS/INS)—to improve ML bit decoding and navigation performance are analyzed. Two vehicular navigation tests are performed in dense foliage and an urban canyon environment. In the context of global positioning system L1 C/A signals, the field test results show that vector tracking and ultratight coupling can improve the successful decoding rate by up to 40% depending on signal strength. This paper also demonstrates how the signal power-based correlator selection method can address high bit error-rate problems when ML bit decoding is used for bit wipe-off in the signal-challenged environment. After implementing this algorithm, the position and velocity accuracy of the stand-alone high-sensitivity GNSS receiver has been improved about 50% after extending coherent integration time from 20 to 100 ms in the vehicular navigation tests.

[1]  Andrey Soloviev,et al.  Deeply Integrated GPS/Low-Cost IMU for Low CNR Signal Processing: Flight Test Results and Real Time Implementation , 2004 .

[2]  M. Kokkonen,et al.  A new bit synchronization method for a GPS receiver , 2002, 2002 IEEE Position Location and Navigation Symposium (IEEE Cat. No.02CH37284).

[3]  Product Summary , 1986, IEEE Micro.

[4]  Dynamic Duo Combined GPS / GLONASS Receivers in Urban Environments , 2011 .

[5]  Gérard Lachapelle,et al.  GNSS Indoor Location Technologies , 2004 .

[6]  Mark G. Petovello,et al.  Multipath Signal Assessment in the High Sensitivity Receivers for Vehicular Applications , 2011 .

[7]  James L. Garrison,et al.  Bit Synchronization and Doppler Frequency Removal at Very Low Carrier to Noise Ratio Using a Combination of the Viterbi Algorithm with an Extended Kalman Filter , 2003 .

[8]  Michael S. Braasch,et al.  Comparison of Two Approaches for GNSS Receiver Algorithms: Batch Processing and Sequential Processing Considerations , 2005 .

[9]  Changdon Kee,et al.  Bit Transition Cancellation Signal Acquisition Method for Modernized GPS and Galileo Signal , 2011 .

[10]  John Y. Hung,et al.  Performance Analysis of Vector Tracking Algorithms for Weak GPS Signals in High Dynamics , 2009, IEEE Journal of Selected Topics in Signal Processing.

[11]  P. Ward,et al.  Satellite Signal Acquisition , Tracking , and Data Demodulation , 2006 .

[12]  Thomas Pany,et al.  Navigation Signal Processing for GNSS Software Receivers , 2010 .

[13]  Letizia Lo Presti,et al.  A differential post detection technique for two steps GNSS signal acquisition algorithm , 2010, IEEE/ION Position, Location and Navigation Symposium.

[14]  bernHArd rIedl,et al.  coherent Integration Time : The longer , the better , 2022 .

[15]  J. K. Ray,et al.  Mitigation of GPS code and carrier phase multipath effects using a multi-antenna system , 2000 .

[16]  Pejman L. Kazemi.  Optimum Digital Filters for GNSS Tracking Loops , 2008 .

[17]  A. Soloviev,et al.  Decoding Navigation Data Messages from Weak GPS Signals , 2009, IEEE Transactions on Aerospace and Electronic Systems.

[18]  B. Eissfeller,et al.  Use of a Vector Delay Lock Loop Receiver for GNSS Signal Power Analysis in Bad Signal Conditions , 2006, 2006 IEEE/ION Position, Location, And Navigation Symposium.

[19]  D. Gebre‐Egziabher,et al.  GNSS Applications and Methods , 2009 .

[20]  John Y. Hung,et al.  A valid comparison of vector and scalar tracking loops , 2010, IEEE/ION Position, Location and Navigation Symposium.

[21]  Mark G. Petovello,et al.  Improving High Sensitivity Receiver Performance in Multipath Environment for Vehicular Applications , 2012 .

[22]  Mark G. Petovello,et al.  Comparison of Vector-Based Software Receiver Implementations With Application to Ultra-Tight GPS/INS Integration , 2006 .

[23]  Tiantong Ren,et al.  An analysis of maximum likelihood estimation method for bit synchronization and decoding of GPS L1 C/A signals , 2014, EURASIP J. Adv. Signal Process..