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In a communication network, a good rate allocation algorithm should reflect the utilities of the users while being fair. We investigate this fundamental problem of achieving the system optimal rates in the sense of maximizing aggregate utility, in a distributed manner, using only the information available at the end hosts of the network. This is done by decomposing the overall system problem into subproblems for the network and for the individual users by introducing a pricing scheme. The users are to solve the problem of maximizing individual net utility, which is the utility less the amount they pay. We provide algorithms for the network to adjust its prices and the users to adjust their window sizes such that at an equilibrium the system optimum is achieved. Further, the equilibrium prices are such that the system optimum achieves weighted proportional fairness. It is notable that the update algorithms of the users do not require any explicit feedback from the network, rendering them easily deployable over the Internet. Our scheme is incentive compatible in that there is no benefit to the users to lie about their utilities.

Abstract-This work develops a discrete-time dynamical feedback system model for a simplified TCP network with RED control and provides a nonlinear analysis that can help in understanding observed parametric sensitivities. The model describes network dynamics over large parameter variations. The dynamical model is used to analyze the TCP-RED operating point and its stability with respect to various RED controller and system parameters. Bifurcations are shown to occur as system parameters are varied. These bifurcations, which involve the emergence of oscillatory and/or chaotic behavior, shed light on the parametric sensitivity observed in practice. The bifurcations arise due to the presence of a nonlinearity in the TCP throughput characteristic as a function of drop probability at the gateway. Among the bifurcations observed in the system are period doubling and border collision bifurcations. The bifurcations are studied analytically, numerically, and experimentally.

ABSTRACT. We study the issue of how to fairly allocate communication rate among the users of a Gaussian multiaccess channel. All users are assumed to value rate equally and each is assumed to have no limit on its desired rate. We adopt a cooperative game-theoretic viewpoint, i.e. it is assumed that the users can potentially form coalitions off line to threaten other users with jamming the channel, using this as an argument for deserving a larger share of the rate. To determine the characteristic function of the game, we first determine the capacity region of the Gaussian multiaccess arbitrarily varying channel, with an operational meaning of capacity somewhat modified from the usual one, which is more appropriate to our context and permits time sharing. We then propose a solution concept for the game through a set of natural fairness axioms and prove that there exists a unique fair allocation that satisfies the axioms. Moreover, we demonstrate that the unique allocation is always feasible and lies in the core of the game. It is also shown to possess some intuitively natural qualitative properties as the signal to noise ratio varies.

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