Signal Space Solutions for GNSS Interference

Precise positioning is available from global navigation satellite systems (GNSS). Unfortunately, satellite signals are weak and a strong interference signal can create a GNSS denial region. The solution requires spatially separating the valid signals from the interference signal. The traditional approach involves constructing a beampattern that puts a sidelobe null in the direction of the interference signal while putting valid signals into the mainlobe or sidelobes. This approach is seen as suboptimal because of array constraints on the beampattern. An alternative approach is presented here that uses linear algebra methods. Physically, all the signals are mapped onto a receive antenna array vector. The signal space approach inverts this mapping which results in a signal vector that completely decouples the valid signals from the interference signal. This allows only the valid signals to be used for positioning. Implementation of this alternative approach yields an adaptive set of antenna array weights calculated using linear algebra methods to decouple all the signals.