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

The effect of platform swinging on a HAPS-CDMA system

“…The center cell Bo is located right at the nadir of the HAPS. The other cells Bj distributed around Eo by the cellular structure with radius R and area S. We assume M users are uniformly distributed on the service area [6], so the use density p is M is ,The geometrical relationship of HAPS' users illustrated in Figure 1.…”

“…In fact, the platform keeps a quasi-stationary state, which causes the platforms receive signal is unstable. Currently, all studies about HAPS basically assumed that the platform is stationary, or only considered platform displacement impact on the assumption that soft handoff happen immediately and no phone drop off [5] [6]. On the other hand, because of the quasi-static of platform, the traditional power control can not ensure the stability of received signals, which will cause the interferences increase and the capacity decreases.…”

“…The swinging model is illustrated in Figure 2. When the platform swinging happens, the angle between the user i and the main beam of cell j change from rp i j to rp � , and the center of the jth cell change from (xj,Yj) to (x�,y�)and the angle between the user i and the main beam of cell 0 change from rpo , i j to rp� , i j' [6] indicated when platform displacement distance d can maintain for a long time, which provides the mobile station sufficient time to complete the soft handoff and no drop call happens. Then the system capacity of the decline was not obvious.…”

“…[5] discussed the impacts of displacement by system simulation; it believed that the vertical displacement had more prominent negative effect than horizontal displacement. [6] discussed the impact on system performances which caused by platform displacement according to two kinds of multi-antenna system: 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. The former one does not occur to soft handoff, while the system capacity decreased 3%.…”

“…In this paper, a novel HAPS-CDMA swinging model with a fixed beam projection pattern which is mentioned the same in [6] is presented. And the new system capacity formula is concluded.…”