Topology transformation based on time division: An improved inter-satellite link structure

Time Division Multiple Access (TDMA) with wide beam antennas is a popular system for establishing inter-satellite links (ISLs) in the Global Positioning System (GPS). After a thorough analysis of the existing ISL structures in the TDMA system, we find that few ISL structures can be able to meet a couple of new requirements such as real-time and rapid data transmission and space-ground joint orbit determination. To address this issue, we design an improved ISL structure called Topology Transformation Based Time Division (TTTD). The TTTD relies on a new link mode called Time-varying Grouping Time Division Duplex (TvGTDD), which is able to ensure the execution of inter-satellite ranging and communication in the same time slot. The TTTD is associated with four top-level parameters, respectively involving the constellation topology transformation period, the constellation ranging period, the time slot period and the inter-satellite communication routing strategy. We carry out simulations to calibrate these parameters in order to achieve the peak performance of the proposed ISL structure.