Departmental Papers (ESE)

Document Type

Journal Article

Date of this Version

July 2004

Comments

Copyright 2004 IEEE. Reprinted from IEEE Transactions on Computers, Volume 53, Issue 7, July 2004, pages 785-797.
Publisher URL: http://ieeexplore.ieee.org/xpl/tocresult.jsp?isNumber=29258&puNumber=12

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Abstract

We study fairness in allocating bandwidth for loss-tolerant real-time multicast applications. We assume that the traffic is encoded in several layers so that the network can adapt to the available bandwidth and receiver processing capabilities by varying the number of layers delivered. We consider the case where receivers cannot subscribe to fractional layers. Therefore, the network can allocate only a discrete set of bandwidth to a receiver, whereas a continuous set of rates can be allocated when receivers can subscribe to fractional layers. Fairness issues differ vastly in these two different cases. Computation of lexicographic optimal rate allocation becomes NP-hard in this case, while lexicographic optimal rate allocation is polynomial complexity computable when fractional layers can be allocated. Furthermore, maxmin fair rate vector may not exist in this case. We introduce a new notion of fairness, maximal fairness. Even though maximal fairness is a weaker notion of fairness, it has many intuitively appealing fairness properties. For example, it coincides with lexicographic optimality and maxmin fairness, when maxmin fair rate allocation exists. We propose a polynomial complexity algorithm for computation of maximally fair rates allocated to various source-destination pairs, which incidentally computes the maxmin fair rate allocation, when the latter exists.

Keywords

Maximal fairness, multicast, discrete bandwidth allocation

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Date Posted: 20 February 2005

This document has been peer reviewed.