Feedback priority control for MPEG video transmitted through ATM networks

Although ATM networks are suitable for transporting variable bit rate (VBR) traffic, bursty moving picture exports group (MPEG) traffic is tending to make the networks congested and results in cell loss. It is suggested that cells should be assigned different priorities according to the significance of the contained information such that the networks can try to protect the high-priority cells and obtain high video quality. Considering the payload behind the slice header, losing any cell would disable the decoding for the following part of the same slice. As a result, if any cell has to be discarded, the farther the position is, the lesser the following data are affected. In this article, a simple mechanism called 'feedback control priority partition with RC-shaper (FBCPP&RC)' is proposed to prevent losing cells at the former position by adaptively assigning high priority to these cells. The decision policy is simple and quick. It also employs an RC-shaper to smooth the burstiness of the cells so as to reduce cell-loss probability. The mechanism is expected to facilitate transmitting MPEG video as a cheaper available bit rate (ABR) traffic rather than VBR traffic. According to the simulation results, it performs well in improving the quality of single-frame as well as continuous pictures. It can also be applied to the new standard MPEG-II.