Differential Correction Map for GNSS

A method comprising:

• determining a virtual reference station constellation (VRSC) of virtual reference stations having respective locations spanning a geographical area;
• generating for a Global Navigation Satellite System (GNSS) a differential correction map (DCM) based on the VRSC, the DCM representing a non-planar surface of differential corrections that varies across a geographical area represented by the DCM;
• and
• transmitting a radio signal that conveys the DCM across the geographical area.

An apparatus comprising:

• memory;
• and
• a processor coupled to the memory and configured to:
• generate for a Global Navigation Satellite System (GNSS) a differential correction map (DCM) representing a non-planar surface of differential corrections that varies across a geographical area represented by the DCM, the differential corrections being based on a reference station constellation of GNSS reference stations having respective locations spanning the geographical area, the GNSS reference stations including physical or virtual reference stations.