Effects of overhead and adaptive data rate control in CDMA ALOHA for shadowed land mobile satellite and HAPS channels

The effects of overhead on the throughput and delay performance of mobile satellite communications using slotted CDMA ALOHA systems are examined. Computer simulation is carried out using measured propagation data, and throughput performances for the different propagation characteristics are compared. The packet delay performance is evaluated along with the altitude of satellite when the ARQ (automatic repeat request) scheme is introduced for error control. Also proposed is the adaptive data rate slotted CDMA ALOHA. In this method the data rate is changed for every packet by the situation of the propagation path and is applied to slotted CDMA ALOHA. The improved throughput, delay time and data rate are shown in case of high traffic.