Satellite transmission system with random access generating random numbers in an area dependent on the channel load

摘要

In a satellite communications system comprising a central station (1) and remote stations (2) each remote station sends a pachet containing user data on a randomly determined slot of a forward satellite channel. If the packet is received by the central station, it sends traffic data and an acknowledgment signal. If the absence of acknowledgment signal is detected by the remote station, it generates a random number in a range determined by the traffic data and increments a count value indicating a number of instances where the acknowledgment signal is not returned. The packet containing the count value is retransmitted on a time slot determined by the random number. If an acknowledgment signal is received, the count value is reset to zero. The central station, on receiving a packet, generates an acknowledgment signal, and derives a sum of the total of packets received during a predetermined interval and the total of count values contained in such packets. The traffic data is derived from the sum and transmitted with the acknowledgment signal and host data on a backward satellite channel. IMAGE