Message-to-Satellite Allocation Strategies for Long GNSS Messages and application to the Galileo High Accuracy Service

Multi-Round Message Scheduling for Fast GNSS Packet Broadcasting

“…Additionally, we remark that unlike other proposed protocols, such as [14], [15], ours are more general and make no particular assumption on the number of packets to be disseminated, the region to be covered, or the SVs' position: thus, we could use this scheme to schedule a message either over a specific region A (e.g., Europe) or using only a limited subset of the satellites, instead of the whole set S, e.g., by scheduling different messages to different subsets of satellites.…”

“…, K} from the ground segment; the choice of π s,n is the true subject of the scheduling discussed in the next Section; 2) satellite s transmits packet π s,n ; 3) each receiver in a position x such that v s,n (x) = 1 decodes the packet; 4) if the receiver has already obtained packet π s,n during previous rounds or from another satellite, it discards the packet, otherwise it stores the packet in its buffer; 5) once the receiver has collected all the K packets, it reconstructs message p and waits for a new message. Note that the proposed protocol is compatible with any channel code mechanism, e.g., the Fountain codes used, for instance, in [1], [9], [14]. Moreover, our solution can also be applied without channel coding.…”

“…Let S 0 be the Galileo GNSS constellation with 24 medium Earth orbit (MEO) satellites distributed over 3 orbital planes with spherical orbits. For a more realistic simulation, we did not consider the whole set S 0 set but only S ⊂ S 0 , the subset of satellites that are connected to one of the uplink station (ULS), as done in [1], [14], [15], [20]. For Galileo, the ULSs are located in Svalbard (78.2 • N, 15.4 • E), Kourou (5.2 • N, 52.7 • W), Papeete (17.5 • S, 149.4 • W), Sainte-Marie, Réunion (20.9 • S, 55.5 • E) and Nouméa (21.9 • S, 166.0 • E).…”

“…Yet, only a few studies are available on this topic, in the literature. Message allocation strategies are proposed for HAS in [14], [15] taking into account the satellite positions but not the actual receivers' visibility. Moreover, in those works, the authors focus on the dissemination of a fixed number of packets (10), while we consider a more general scheduling problem.…”