A Stability Conjecture on Bandwidth Sharing Networks

N. S. Walton and M.R.H. Mandjes

Paper (updated since journal version): [pdf]

Abstract

We consider a queueing model where documents are simultaneously transferred over a communication network. The bandwidth allocated to each document transfer is assumed to be the solution of a utility optimization problem. Under a natural stability condition and under the assumption that document arrivals are Poisson and that document sizes are independent exponential distributions, such queueing models have been proven to be positive recurrent. It has been conjectured for a decade that the assumption of exponentially distributed documents can be removed. There exist numerous generalizations without this exponential assumption, but a general proof remains elusive.


Important Comment

We are now aware of significant progress made in this conjecture, in particular, by Nam Lee in his PhD thesis [1] and in the soon to appear paper by Paganini et al. [2]. The PhD thesis by Nam Lee links fluid equations to the stability of the bandwidth model. In particular, the work of Lee [1] shows, under a condition that bounds the tails of the first moment, that one is able to show positive Harris recurrence of a general file size model. In addition, Paganini et al. [2] apply the approach of Lee for their Lyapunov function and derive positive recurrence results. This work, to appear, closes the conjecture for relatively light-tailed documents sizes, the conjecture for all heavy-tailed document sizes with finite first moments remains open.

[1] A sufficient condition for stochastic stability of an Internet congestion control model in terms of fluid model stability,
Lee, N.H. (2008). PhD thesis, University of California at San Diego.

[2] Network Stability under Alpha Fair Bandwidth Allocation with General File Size Distribution.
Paganini, F., Tang, A., Ferragut, A. and Lachlan, A. L. H. (to appear 2012). IEEE Transactions on automatic control.


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Last updated August 19, 2011.