Research on Single Frequency BDSBAS Message Scheduler Improvement

With the increasingly high performance requirements of civil aviation for satellite navigation system, Satellite-Based Augmentation System (SBAS) is applied. SBAS can augment Global Navigation Satellite System (GNSS) by broadcasting correction and integrity parameters to users in service area through geostationary satellites (GEOs). Therefore, reasonable schedule and normal broadcast of SBAS messages are important guarantee for SBAS to provide efficient service. By analyzing the single frequency SBAS message scheduler at home and abroad, and combining with the current broadcast messages of the BeiDou Satellite-Based Augmentation System (BDSBAS), this paper proposes a fixed time sequence dynamic message scheduler for BDSBAS. Compared with the fixed sequence message scheduler adopted by BDSBAS at present, the message scheduler proposed in this paper can not only improve the flexibility of message broadcasting, but also achieve the effective message proportion of 100%. On the basis of meeting the message update cycle specified by the International Civil Aviation Organization Standards and Recommended Practices (ICAO SARPs), the update time of all kinds of messages is shortened, and the time required for users to receive all message types for the first time is reduced about 11.7%, which provides more time slot margin support for message alarm and upload failure, and greatly ensures the integrity and continuity of BDSBAS service.