Required Memory Analysis of a GPS Receiver for Implementing CHIMERA SCA

Signal authentication technology is being adopted for the newly developed and modernized GNSS for secured satellite navigation. Chips-Message Robust Authentication (CHIMERA) is being developed by the Air Force Research Laboratory (AFRL) to explore future GPS authentication methods. CHIMERA will support not only Navigation Message Authentication (NMA) but also Spreading Code Authentication (SCA), which is considered a more robust countermeasure against intentional interferences. For a receiver to authenticate the GPS signal through SCA, it needs to store the raw GPS signal, and this is a newly added feature to the receiver. This study aimed to analyze the required memory for implementing the new feature. Two methods were compared the conventional snapshot and compression methods. Simulations were done to compare the SCA verification performance of these two methods under various sampling rates, quantization levels, and preprocessing approaches. As a result, the required memory for each method concerning the various receiver characteristics was addressed.