Gaurav Raina

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Rate control protocols that utilise explicit feedback from routers are able to achieve fast convergence to an equilibrium which approximates processor-sharing on a single bottleneck link, and hence such protocols allow short flows to complete quickly. For a network, however, processor-sharing is not uniquely defined but corresponds with a choice of fairness(More)
This article describes how control theory has been used to address the question of how to size the buffers in core Internet routers. Control theory aims to predict whether the is stable, i.e. whether TCP flows are desynchronized. If flows are desynchronized then small buffers are sufficient [14 ]; the theory here shows that small buffers actually promote(More)
We perform the necessary calculations to determine the stability and asymptotic forms of solutions bifurcating from steady state in a nonlinear delay differential equation with a single discrete delay. The results are used to examine the loss of local stability in a selection of congestion control algorithms employed over a single link. In particular, we(More)
Unmanned Aerial Vehicles (UAVs) are currently a very interesting field of research in the modern scientific community, especially in their application to military operations. In this paper we focus on the Tilt-rotor UAV. This is a UAV capable of Vertical Take-Off and Landing (VTOL), with a rotor on each side of its airframe. Each rotor can be tilted(More)
It is generally accepted that buffers, in Internet routers, should be much smaller than the currently deployed bandwidth-delay product rule. However, as yet, there is no consensus on the optimal buffer-sizing strategy. Our focus will be on the performance, with respect to sizing buffers, of transport protocols that use queuing delay and packet loss as their(More)
There are many factors that are important in the design of queue management schemes for routers in the Internet: for example, queuing delay, link utilization, packet loss, energy consumption and the impact of router buffer size. By considering a fluid model for the congestion avoidance phase of Additive Increase Multiplicative Decrease (AIMD) TCP, in a(More)
In this note we analyse various stability properties of the max-min fair Rate Control Protocol (RCP) operating with small buffers. We first tackle the issue of stability for networks with arbitrary topologies. We prove that the max-min fair RCP fluid model is globally stable in the absence of propagation delays, and also derive a set of conditions for local(More)
Motivated by recent concerns that queuing delays in the Internet are on the rise, we conduct a performance evaluation of Compound TCP in two topologies. The first topology consists of a single bottleneck, and the second consists of two distinct sets of flows, regulated by two edge routers, feeding into a core router. We consider long-lived flows, and a(More)
We analyse the stability of FAST TCP, a new proposal for TCP, in three limiting regimes. When the queue is modelled as an integrator, the fluid model may lose local stability as the feedback delay varies. Loss of local stability is shown to occur via a Hopf bifurcation, and we analytically characterise the asymptotic orbital stability of the bifurcating(More)
Reaction delays play an important role in determining the qualitative dynamical properties of a platoon of vehicles driving on a straight road. In this paper, we investigate the impact of delayed feedback on the dynamics of two widely-studied car-following models; namely, the classical car-following model and the optimal velocity model. We first conduct a(More)