Throughput performance improvement of spread-slotted ALOHA in mobile satellite communications

Application of spread spectrum techniques in conventional slotted ALOHA, namely spread-slotted ALOHA, offers relatively high capacity multiple simultaneously packet transmissions. Two adaptive versions of the transmit permission control (TPC) scheme applicable in multi-cell communication systems are proposed. In the basic TPC scheme, by prohibiting the transmissions from the users with relatively high propagation loss to their connecting hub stations, the level of multiple access interference is decreased, and hence the throughput characteristics are improved. In the proposed schemes, the prohibition condition becomes more intelligent by considering the level of the offered traffic loads to the hub stations. It is shown that the adaptive schemes exhibits significantly improved characteristics at all offered traffic loads