An Adaptive Topology Optimization Strategy for Intersatellite Links in GNSS

Intersatellite links (ISLs) are an effective way for the global navigation satellite system (GNSS) to reduce its dependence on ground infrastructures, which guarantees constellation orbit determination and satellite communication. When the number of onboard Ka-band antennas is less than that of visible satellites, ISL assignment of GNSS cause a problem. For the problem of ISL scheduling, considering that the result of the allocated link has a feedback effect on the subsequent link assignment as a priori knowledge, an adaptive topology optimization algorithm based on signed variance is proposed. In order to meet the requirements of the communication and ranging performance, the time slots are divided into communication time slots and ranging time slots. Taking the communication time delay from overseas satellites to anchor satellites and position dilution of precision as measurement indexes, the proposed strategy is simulated for 10 080 min. The results show that the ranging performance of this strategy is better than other recently published methods, which verifies the effectiveness of signed variance for adaptive link planning and is also beneficial to the survivability of constellation.