- Author: A. Proutiere and T. Bonald
Title: Maximum stability of networks with non-convex
Abstract: Wireless networks where base stations interact through
interference typically have non-convex rate regions. By scheduling the
extremal points of the rate region only, one can ensure maximum
stability in the sense that the stability region is the convex hull of
the rate region. This typically requires the cooperation of the base
stations, however. In this talk, we analyse the ability of usual
allocations like proportional fairness, for which decentralized schemes
exist, to ensure maximum stability.
- Author: Nicolas Bonneau
Title: Correlated Equilibrium for multi-user OFDMA
- Author: C. D. Charalambous
Title: Control of Uncertain Dynamical Systems via
Limited Capacity Communication Channels
Abstract: In this presentation, an information theoretic framework
is discussed for controlling uncertain dynamical systems over
limited capacity uncertain communication channels. The methodology
employs tools from Shannon's theory of reliable communication and
robustness of uncertain dynamical systems, as follows.
1) The classical information theoretic measures of entropy rate
and channel capacity are defined for a family of source
distributions and channel transition distributions, respectively.
2) The classical Shannon rate distortion lower
bound is defined for a family of source distributions.
3) The notions of observability and stabilizability of
a family of control dynamical systems is related
to rate distortion of the source and its reconstruction.
By invoking 1)-3) and the information transmission theorem, necessary
condition for the existence of an encoder, decoder and feedback
controller over the communication channel are derived for uniform
stabilizability and observability of the dynamical system.
When applied to Gauss Markov controlled processes,
the necessary condition states that the capacity of the
channel should be at least equal to the sum of the logarithms
of the unstable eigenvalues associated with the open loop Gauss Markov
- Author: N. Hegde
Title: Combined Cell Selection and Inter-Cell Scheduling
in Wireless Data Networks
Abstract: We examine the potential capacity gains in
wireless data networks such as UMTS/HSDPA and
CDMA 1xEV-DO from cell coordination which combines
inter-cell scheduling and optimal cell selection. The inter-cell
scheduling involves coordinating the activity phases of interfering
stations so as to avoid inter-cell interference and boost the
transmission rates. The cell selection aims at improving the
by assigning users to base stations based on load and other relevant
considerations in addition to signal strength conditions. We consider a
dynamic setting where users come and go over time as governed by the
arrival and completion of random finite-size data transfers, and
evaluate the capacity gains in terms of the maximum sustainable network
throughput for a given spatial traffic pattern. We demonstrate that the
relative merits of inter-cell scheduling and cell selection strongly
depend on the network topology
- Author: F. Baccelli
Title: Summary of related research activity at TREC
- Author: M. Dirani
Title: Ressource allocation in heterogenes environnements.
- Author: Can Emre Koksal
Perspectives on Time Varying Wireless Communication Networks
The quality of communication over a wireless channel depends
on many different parameters. It can vary dramatically over time and is
known to change with slight environmental changes. Therefore, treating
network layer issues such as network delay, routing and traffic
engineering, separately from physical layer issues such as channel
modeling, detection and coding leads to a loss of complete understanding.
In this work, we introduce a model that captures the time varying
characteristics of a wireless channel in a form that could be directly
translated into network and application layer quality constraints. In a
sense, the model projects certain parameters of the physical layer onto
the space of networking parameters which enables us to better understand
the impact of physical layer variability on the networking performance.
First, we show that the channel variability may affect the networking
performance quite differently depending on its time scale. Then we
establish further connections between the two layers using the notion
of ``effective number of transmissions'' (ENT). ENT is motivated by the
idea of effective bandwidths which is used to model variable rate sources
in many traffic engineering problems. We illustrate that ENT captures
the statistical properties of the channel in such a way that problems of
routing and opportunistic multiple access over variable channels resemble
those in fixed (wired) channels. We also present experimental results
taken from sensor and mesh networks for further illustration.
- Author: E. Altman (joint work with K. Avratchenkov,
G. Miller and R. Marquez)
Title: A stochastic game framework for obtaining capacity limits for
Markovian channels under adversarial conditions
Abstract: We study an uplink power control problem in a CDMA network.
A group of subscribers transmit data to a base station
over wireless channels, in the presence of a malicious node
that tries to jam the
communication. The transmission power of the subscribers
is assumed to be controlled by the base station which
transmits the requested power levels.
Both the subscribers' terminals as well as the jamming
terminal have constraints on their average transmission power.
Using a zero-sum game formulation,
we identify the most harmful behavior of
the jammer as well as a robust power control policy for the
subscribers' terminals that guarantee the best performance
under worst case jamming conditions.
E. Altman, K. Avrachenkov, R. Marquez and G. Miller,
"Zero-sum constrained stochastic games with independent state
Math. Meth. Oper. Res., Vol. 62, pp. 375-386, Dec. 2005.
E. Altman, A. Konstantin, G. Miller, B. Prabhu,
"Uplink dynamic discrete power control in cellular networks",
Inria Research Report, RR-5818, 2006.
Availablr as INRIA