This paper presents an adaptive end-to-end protocol for quality of service (QoS)-sensitive transport of real-time MPEG video using packet-level forward error correction in dynamic networks. The objective is to facilitate a user-specified QoS end-to-end, i.e., without special network support-for real-time MPEG video traffic whose timing constraints rule out the use of retransmission-based congestion control and QoS provisioning schemes. In previous work, we proposed an adaptive packet-level FEC protocol called AFEC and analyzed its properties with respect to optimality and stability. The control problem is nontrivial due to the fact that increased redundancy, beyond a certain point, can "backfire" resulting in self-induced congestion which impedes the timely recovery of information (e.g., MPEG video frames) at the receiver. We extend the previous work by implementing and customizing AFEC to the transport of real-time MPEG video, realizing the system as a transport and application layer protocol called MAFEC running end-to-end on UNIX workstations, and measuring its performance over controlled network environments. We show that MAFEC is able to effectively hide potentially adverse network effects such as packet drops and delays stemming from traffic burstiness and nonstationary structural changes using adaptive redundancy control, exporting a constant-QoS service commensurate with user-specified, desired QoS.
['Kihong Park', 'W. Wang']
QoS-sensitive transport of real-time MPEG video using adaptive forward error correction