Comparison of three access protocols for VSAT networks

The performance of three access protocols for data communications on very small aperture terminal (VSAT) satellite networks under erroneous inbound channel is compared. Selective repeat and go-back-N automatic repeat request strategies are used for correcting erroneous packets. Single channel per carrier-sequential access (SCPC-SA) and adaptive assignment time division multiple access (AA-TDMA) combine random and demand assignment access; adaptive priority demand assignment (APODA) is a variant of CPODA. A mixed load of interactive traffic and file transfer is assumed. The protocols are modeled by queuing networks. Results show that SCPC-SA and AA-TDMA are favorable if the load is low. A pure reservation protocol is preferable for high loads and guarantees an acceptable delay of interactive messages