... 2G systems will bereviewed briefly.MacrocellMicrocellSatellite spotbeamFigure 2.1 Microcells, macrocells, and a satellite spot-beam402 CELLULAR MOBILE COMMUNICATION SYSTEMS: FROM 1G TO 4G2.4 ... macrocellular layer. A space segmentmay be added to the terrestrial segment, where satellite spot beams overlay clustersof terrestrial macrocells [65], as illustrated in Figure 2.1. GSM, the ... instance in the shape ofhierarchical cellular structures, to provide high-speed mobility and hot-spot capacity.This list will be expanded in the following, first with respect to the initial 3G require-ments...