Combined Random/Reservation Access for Packet Switched Transmission Over a Satellite with On-Board Processing: Part I--Global Beam Satellite

A combined random/reservation multiple access (CRRMA) scheme for packet-switched communication over a global beam satellite with on-board processing is proposed and analyzed. Channel time is divided into contiguous slots; each slot contains minislots for transmission of request packets and minislots for data. With substantially smaller than the number of earth stations, collisions will occur in request packet transmissions. Two channel access algorithms for the CRRMA model are proposed: uncontrolled channel access (UCA) and controlled channel access (CCA). UCA is simpler but has an inherent stability problem particularly when the number of minislots is small. The CCA algorithm restricts the transmission of request packets for new arrivals to take place only when the slot is in the FREE state. With , the CCA algorithm exhibits good delay-throughput characteristics. As increases, the UCA algorithm offers stable operation. For the simpler UCA algorithm is preferred over CCA.