Development Recommendation of Inter-satellites Links in GNSS

Global Positioning System (GPS) block IIR and IIF satellites have fixed crosslink transponder with UHF band,and future GPS block Ⅲ satellites will have directional Ka-band inter-satellites links (ISLs) to replace UHF-band ISLs,which can increase communications capacity and anti-jamming capability. Global navigation satellite system (GLONASS) of Russia has armed new generation satellites (GLONASS-K) with S-band crosslinks. Plans of ISLs for Galileo satellite navigation systems of Europe are in preparation. Chinese Compass satellite navigation system is in the interim from China region to the worldwide,and the architecture of ISLs of Compass is in a dilemma. Based on the research of many types of ISLs aboard and issued from requirements and characteristics of ISLs in Global Navigation Satellite Systems(GNSS),this paper recommends that directional ISLs with higher frequency band should be adopted in GNSS. Other pieces of advice are integrated design between crosslink antennas and spacecraft,flexible network protocol between satellites,and consistency of ISL products in navigation constellation. The development recommendation in this paper,as a selection of GNSS ISL system,can guide researchers and engineers to construction of advanced ISLs for Compass,which takes into consideration pre-sent technology level and future technique trend of ISLs.