AN ATM-LIKE SYSTEM ARCHITECTURE FOR SATELLITE COMMUNICATIONS INCLUDING ON-BOARD SWITCHING

In this paper, an ATM system architecture for satellite communications is described. The proposed architecture includes an on-board switch and implements the adaptation of real-time services (e.g. voice and video) and non-real-time services (e.g. data) to the satellite communication link, while achieving statistical advantage. To this end, the ATM traffic categories defined in recent specifications^1,2 are utilized. Real-time and non-real-time traffic components are simultaneously supported by a TDMA/TDM on the satellite uplink/downlink, respectively. By exploiting the burstiness of real-time traffic, the proposed satellite system architecture achieves a significant increase of the overall system throughput. After describing the satellite system architecture and addressing scheme, we derive analytical models, by using sophisticated queueing models that allow a very accurate performance evaluation and an easy dimensioning of the data buffers. The proposed model is validated with simulations. The main result is the assessed feasibility of on-board buffers with current technology, even under very strict performance requirements on cell loss ratio and for quite high load values (e.g. 80 per cent of the downlink capacity). Finally, a congestion control scheme, based on a combination of preventive and reactive strategies, is proposed and analysed.