28,448 research outputs found
Routing Games with Progressive Filling
Max-min fairness (MMF) is a widely known approach to a fair allocation of
bandwidth to each of the users in a network. This allocation can be computed by
uniformly raising the bandwidths of all users without violating capacity
constraints. We consider an extension of these allocations by raising the
bandwidth with arbitrary and not necessarily uniform time-depending velocities
(allocation rates). These allocations are used in a game-theoretic context for
routing choices, which we formalize in progressive filling games (PFGs).
We present a variety of results for equilibria in PFGs. We show that these
games possess pure Nash and strong equilibria. While computation in general is
NP-hard, there are polynomial-time algorithms for prominent classes of
Max-Min-Fair Games (MMFG), including the case when all users have the same
source-destination pair. We characterize prices of anarchy and stability for
pure Nash and strong equilibria in PFGs and MMFGs when players have different
or the same source-destination pairs. In addition, we show that when a designer
can adjust allocation rates, it is possible to design games with optimal strong
equilibria. Some initial results on polynomial-time algorithms in this
direction are also derived
Hierarchical Beamforming: Resource Allocation, Fairness and Flow Level Performance
We consider hierarchical beamforming in wireless networks. For a given
population of flows, we propose computationally efficient algorithms for fair
rate allocation including proportional fairness and max-min fairness. We next
propose closed-form formulas for flow level performance, for both elastic (with
either proportional fairness and max-min fairness) and streaming traffic. We
further assess the performance of hierarchical beamforming using numerical
experiments. Since the proposed solutions have low complexity compared to
conventional beamforming, our work suggests that hierarchical beamforming is a
promising candidate for the implementation of beamforming in future cellular
networks.Comment: 34 page
On Money as a Means of Coordination between Network Packets
In this work, we apply a common economic tool, namely money, to coordinate
network packets. In particular, we present a network economy, called
PacketEconomy, where each flow is modeled as a population of rational network
packets, and these packets can self-regulate their access to network resources
by mutually trading their positions in router queues. Every packet of the
economy has its price, and this price determines if and when the packet will
agree to buy or sell a better position. We consider a corresponding Markov
model of trade and show that there are Nash equilibria (NE) where queue
positions and money are exchanged directly between the network packets. This
simple approach, interestingly, delivers improvements even when fiat money is
used. We present theoretical arguments and experimental results to support our
claims
Multipath streaming: fundamental limits and efficient algorithms
We investigate streaming over multiple links. A file is split into small
units called chunks that may be requested on the various links according to
some policy, and received after some random delay. After a start-up time called
pre-buffering time, received chunks are played at a fixed speed. There is
starvation if the chunk to be played has not yet arrived. We provide lower
bounds (fundamental limits) on the starvation probability of any policy. We
further propose simple, order-optimal policies that require no feedback. For
general delay distributions, we provide tractable upper bounds for the
starvation probability of the proposed policies, allowing to select the
pre-buffering time appropriately. We specialize our results to: (i) links that
employ CSMA or opportunistic scheduling at the packet level, (ii) links shared
with a primary user (iii) links that use fair rate sharing at the flow level.
We consider a generic model so that our results give insight into the design
and performance of media streaming over (a) wired networks with several paths
between the source and destination, (b) wireless networks featuring spectrum
aggregation and (c) multi-homed wireless networks.Comment: 24 page
Towards Fast-Convergence, Low-Delay and Low-Complexity Network Optimization
Distributed network optimization has been studied for well over a decade.
However, we still do not have a good idea of how to design schemes that can
simultaneously provide good performance across the dimensions of utility
optimality, convergence speed, and delay. To address these challenges, in this
paper, we propose a new algorithmic framework with all these metrics
approaching optimality. The salient features of our new algorithm are
three-fold: (i) fast convergence: it converges with only
iterations that is the fastest speed among all the existing algorithms; (ii)
low delay: it guarantees optimal utility with finite queue length; (iii) simple
implementation: the control variables of this algorithm are based on virtual
queues that do not require maintaining per-flow information. The new technique
builds on a kind of inexact Uzawa method in the Alternating Directional Method
of Multiplier, and provides a new theoretical path to prove global and linear
convergence rate of such a method without requiring the full rank assumption of
the constraint matrix
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