An area is divided into regions or cells each having an associated multicast group address. The cells are organized using a quad-tree data structure that is dynamically updated. Mobile entities within a given cell elect one of their members as coordinator for assessing cost data associated with subdividing...http://www.google.com.au/patents/US7065576?utm_source=gb-gplus-sharePatent US7065576 - Dynamic multicast grouping for vehicles and other mobile objects
