Collective bit synchronization for weak GNSS signals using multiple satellites

A collective bit synchronization approach is proposed for weak GNSS signals using multiple satellites. Monte Carlo simulation, a GNSS simulator test and a vehicular field test are used to assess the performance and the validity of this approach. The results show that collective bit synchronization, by combining 11 satellites with same signal power levels, has 8 dB sensitivity improvement over traditional ML bit synchronization. In the strong and weak signal mixed channel, collective bit synchronization can achieve perfect synchronization for 15 dB-Hz signal by only requiring two data bits. Collective bit synchronization is also shown to detect bit boundary positions more than 200 times faster than the traditional maximum likelihood bit synchronization for a weak signal.