11. Study on GNSS Inter-System Interference

Nowadays, primarily been driven, among other motivations, by the desire to ameliorate the compatibility performance of GNSS, speculation has continued on the possibility of further optimization. Of special interests is the inter-system interference that one satellite navigation system will suffer due to another navigation system. To analyze inter-system interference, the method recommended by International Telecommunication Union (ITU) is provided in this paper. Traditional methods for code division performance analyzing are generally based on the correlation characteristics of PRN. However, actual inter-signal interference rests also with the correlation characteristics of signal waveforms, with contributions such as data bit reversal, code phase error, Doppler frequency shift and code waveform, etc. closely associated. As a result, coefficient accounting signal-to-noise ratio reduce at correlator output, due to inter-system interference, is proposed in detail in this paper. Then, calculation results of coefficients between several kinds of GNSS signals, and inter-system interference between GPS L5 and Compass B2a, are presented. In the end, conclusions are drawn as to which two signals have greater interference on each other, and how to design navigation signals to improve compatibility performance of GNSS. Based on the researches in this paper, it can be verified that, Compass B2a and GPS L5 can perfectly achieve compatibility.