Structural properties of a low Earth orbit satellite constellation - the Walker delta network

The Walker (1984) delta satellite constellation appears to be practical to serve as a low Earth orbit satellite network to provide world-wide networking. The structural properties of the Walker delta network, including diameter, mean message traversal, traffic density, and network saturation conditions are investigated and presented. Three different traffic patterns are used in this study. It has been found that for a fixed number of satellites, the Walker delta network can provide minimum mean message traversal, minimum traffic density and maximum traffic injection rate provided that the number of orbital planes is equal to the number of satellites in each orbital plane. Regarding the injection of messages from ground stations to the satellite network, the network with a smaller size can accept more messages than a network with a larger size before the network saturates. Furthermore, an adaptive routing algorithm, which always routes the message to its destination through one of several available minimal paths, is also presented