QoS-oriented traffic management in multimedia satellite systems

摘要

The next generation of satellite systems will likely use some on-board switching techniques enabling the direct transmission of data from any up-link spot-beam to any down-link spot-beam. If the switch used in the payload of the system is an ATM-based shared buffer switch, some losses and delays can occur. Fortunately, these drawbacks can be fought thanks to some buffer management policies (HSPO, SMXQ, EPD) that either ensure low delay or low loss ratio. Real-time (voice or MPEG video streams) and non-real-time applications (file transfer, email, web browsing using TCP/IP protocols) should be carried over these satellite systems with different quality of service (QoS) requirements. Different combinations of buffer management policies are presented to guaranty the QoS required by the user. Especially, special emphasis is put on the way to transmit efficiently layer 3 messages (IP datagrams) within a mix of traffic in order to avoid some high layer retransmission techniques (provided in TCP for instance) wasting both time and bandwidth.