PERFORMANCE ANALYSIS OF INTEGRATED-SERVICES LOAD-ADAPTIVE TDMA SATELLITE NETWORKS

A load-adaptive/TDMA multiple-access communications system which serve s to interconnect broad-band multimedia packet streams is considered. In particular, the use of a satellite backbone communications link who se channels are dynamically assigned to network stations is investigat ed. Each station supports packetized voice and data message streams. I ncoming streams to a station are statistically multiplexed by the stat ion across the backbone channels currently allocated to this station. To enhance the multiplexing process, a variable bit-rate packet-voice encoding scheme is also employed. Stations periodically issue requests for backbone channel allocations, based upon their estimated loading status. We introduce two distinct multiple-access algorithms for alloc ating the shared backbone channels to the stations. We develop analyti cal methods for the analysis and design of such integrated multiplexin g/multiple-access networks. Performance measures include voice and dat a packet delays and packet blocking probabilities. Voice stream perfor mance is also characterized by the average number of bits per sample u sed by the voice encoding scheme. The effects of the propagation delay across the backbone link are especially demonstrated. Also illustrate d are the performance improvements attained due to the use of the load -adaptive/TDMA scheme. Under the example of the 'all-voice' traffic lo ading, an LA/TDMA scheme exhibits no obvious performance improvement o ver a fix-assigned scheme. However, as the burstiness of the traffic l oading increases in the example of the 'data-voice' traffic loading, a significant amount of improvement (36 per cent bandwidth savings) is realized by a LA/TDMA scheme.