The effect of platform displacement on a HAPS CDMA system with multibeam antennas

High altitude platform stations (HAPSs) can be displaced by stratospheric winds. In this paper, a HAPS code division multiple access (CDMA) cellular system is considered, and the impact of platform displacement on both the cell deployment movement and the uplink and downlink capacity is examined under two types of multibeam antennas. One type is that the directions of the main lobes can be adapted to make cell centers stay unchanged during platform displacement; the other is with a fixed beam projection pattern at all times. From numerical results it is observed that the former is effective in minimizing cell deployment movement, whereas the latter is advantageous to avoid capacity variations.