159 research outputs found
Altruism in groups: an evolutionary games approach
We revisit in this paper the relation between evolution of species and the
mathematical tool of evolutionary games, which has been used to model and
predict it. We indicate known shortcoming of this model that restricts the
capacity of evolutionary games to model groups of individuals that share a
common gene or a common fitness function. In this paper we provide a new
concept to remedy this shortcoming in the standard evolutionary games in order
to cover this kind of behavior. Further, we explore the relationship between
this new concept and Nash equilibrium or ESS. We indicate through the study of
some example in the biology as Hawk and Dove game, Stag Hunt Game and Prisoner
Dilemma, that when taking into account a utility that is common to a group of
individuals, the equilibrium structure may change dramatically. We also study
the multiple access control in slotted Aloha based wireless networks. We
analyze the impact of the altruism behavior on the performance at the
equilibrium
Dynamic Retransmission Limit Scheme in MAC Layer for Routing in Multihop Ad hoc Networks
We consider a wireless ad hoc network with random
access channel. We present a model that takes into account topology, routing, random access in MAC layer, and forwarding probability. In this paper, we focus on drawing benefit from the interaction of the MAC (governed by IEEE 802.11 or slotted Aloha) and routing by defining a new cross-layer scheme for routing based on the limit number of retransmission.
By adjusting dynamically and judiciously this parameter in a saturated network, we have
realized that both stability of forwarding queues and average throughput are significantly improved in linear networks with symmetric traffic: a gain of 100% can be reached. While in asymmetric topology network with asymmetric traffic, we achieve a better average delay (resp., throughput) for each connection without changing the average throughput (resp.,
delay). In addition, we show the efficiency of our new scheme in case of multimedia applications with delay constraint. A detailed performance study is presented using analytical and simulation evaluation
Forever Young: Aging Control For Smartphones In Hybrid Networks
The demand for Internet services that require frequent updates through small
messages, such as microblogging, has tremendously grown in the past few years.
Although the use of such applications by domestic users is usually free, their
access from mobile devices is subject to fees and consumes energy from limited
batteries. If a user activates his mobile device and is in range of a service
provider, a content update is received at the expense of monetary and energy
costs. Thus, users face a tradeoff between such costs and their messages aging.
The goal of this paper is to show how to cope with such a tradeoff, by devising
\emph{aging control policies}. An aging control policy consists of deciding,
based on the current utility of the last message received, whether to activate
the mobile device, and if so, which technology to use (WiFi or 3G). We present
a model that yields the optimal aging control policy. Our model is based on a
Markov Decision Process in which states correspond to message ages. Using our
model, we show the existence of an optimal strategy in the class of threshold
strategies, wherein users activate their mobile devices if the age of their
messages surpasses a given threshold and remain inactive otherwise. We then
consider strategic content providers (publishers) that offer \emph{bonus
packages} to users, so as to incent them to download updates of advertisement
campaigns. We provide simple algorithms for publishers to determine optimal
bonus levels, leveraging the fact that users adopt their optimal aging control
strategies. The accuracy of our model is validated against traces from the
UMass DieselNet bus network.Comment: See also http://www-net.cs.umass.edu/~sadoc/agecontrol
Flow Level QoE of Video Streaming in Wireless Networks
The Quality of Experience (QoE) of streaming service is often degraded by
frequent playback interruptions. To mitigate the interruptions, the media
player prefetches streaming contents before starting playback, at a cost of
delay. We study the QoE of streaming from the perspective of flow dynamics.
First, a framework is developed for QoE when streaming users join the network
randomly and leave after downloading completion. We compute the distribution of
prefetching delay using partial differential equations (PDEs), and the
probability generating function of playout buffer starvations using ordinary
differential equations (ODEs) for CBR streaming. Second, we extend our
framework to characterize the throughput variation caused by opportunistic
scheduling at the base station, and the playback variation of VBR streaming.
Our study reveals that the flow dynamics is the fundamental reason of playback
starvation. The QoE of streaming service is dominated by the first moments such
as the average throughput of opportunistic scheduling and the mean playback
rate. While the variances of throughput and playback rate have very limited
impact on starvation behavior.Comment: 14 page
Emergence of Equilibria from Individual Strategies in Online Content Diffusion
Social scientists have observed that human behavior in society can often be
modeled as corresponding to a threshold type policy. A new behavior would
propagate by a procedure in which an individual adopts the new behavior if the
fraction of his neighbors or friends having adopted the new behavior exceeds
some threshold. In this paper we study the question of whether the emergence of
threshold policies may be modeled as a result of some rational process which
would describe the behavior of non-cooperative rational members of some social
network. We focus on situations in which individuals take the decision whether
to access or not some content, based on the number of views that the content
has. Our analysis aims at understanding not only the behavior of individuals,
but also the way in which information about the quality of a given content can
be deduced from view counts when only part of the viewers that access the
content are informed about its quality. In this paper we present a game
formulation for the behavior of individuals using a meanfield model: the number
of individuals is approximated by a continuum of atomless players and for which
the Wardrop equilibrium is the solution concept. We derive conditions on the
problem's parameters that result indeed in the emergence of threshold
equilibria policies. But we also identify some parameters in which other
structures are obtained for the equilibrium behavior of individuals
- …