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1. P. Lassila and S. Aalto, Combining opportunistic and size-based scheduling in wireless systems, in Proceedings of ACM MSWiM, pp. 323-332, 2008, Vancouver, CA (bib)

   Abstract: HSDPA/HDR systems allow the use of sophisticated scheduling mechanisms known as opportunistic schedulers that can utilize information on instantaneous channel conditions. On the other hand, for elastic data traffic the size of the files can be used in size-dependent scheduling methods, e.g., the well known SRPT scheduler, to minimize the flow delays. In this paper, we consider the optimal use of both size and channel information for minimizing the flow delay. We derive several heuristics which utilize both types of information. In a static setting with two flows and two rates, the optimal policy can be constructed via a dynamic programming approach and the policies using exact size knowledge can be compared against this. In the dynamic setting, where flows arrive in a stochastic manner and have random sizes, extensive simulations have been performed to evaluate the relative performance of the schedulers under heavy traffic. In the symmetric setting the trade offs involved in the different schedulers are clearly visible, while in the asymmetric the dynamics are more complex. The results still show that significant gains can be achieved with additionally using size information compared with the standard PF scheduler.