@Inproceedings{Zhou-GLOBECOM04,
  author =   "Wei, J. and Xu, C.-Z. and Zhou, X.",
  title =    "A Robust Packet Scheduling algorithm for
                  Proportional Delay Differentiation services",
  booktitle =    "Proc. of IEEE Globecom, Vol.2",
  year  = 2004,
  pages = "697--701"}