QOS based performance of selective repeat transport user in hybrid ATM/TDMA networks

The selective repeat (SR) transport user end-to-end throughput and delay characteristics are analyzed in a hybrid asynchronous transfer mode/time division multiple access (ATM/TDMA) network. The SR transport user is assumed with an underlying cell-level global congestion control in the ATM multiplexer node. The analysis is based on the interaction of packet level control with the queue management at the ATM cell level. The end-to-end transport users are assumed over an M-node virtual circuit (VC) to derive the throughput and delay using Norton equivalent queueing model. The transport service characteristic of the model is obtained from the end-to-end protocol efficiency. The ATM layer is assumed with a leaky bucket (LB), virtual leaky bucket (VLB), modified LB (mLB), or modified VLB (mVLB) congestion control. A global congestion control scheme prioritizes transit traffic over local traffic and ensures the quality of service (QOS) to several classes of traffic. Based on global congestion status, the transport users modulate their end-to-end flow control parameters, i.e., packet size for video and voice users and window size for data users. The probability of cell-loss at the ATM layer is reflected at the transport layer to derive the effective throughput and delay characteristics. The mVLB scheme consistently provided better end-to-end throughput and delay performance for SR transport user.