805 research outputs found
A Generic Approach to Coalition Formation
We propose an abstract approach to coalition formation that focuses on simple
merge and split rules transforming partitions of a group of players. We
identify conditions under which every iteration of these rules yields a unique
partition. The main conceptual tool is a specific notion of a stable partition.
The results are parametrized by a preference relation between partitions of a
group of players and naturally apply to coalitional TU-games, hedonic games and
exchange economy games.Comment: 21 pages. To appear in International Game Theory Review (IGTR
Coalitional Matchings
A coalitional matching is a two-sided matching problem in which agents on each side of the market may form coalitions such as student groups and research teams who - when matched - form universities. We assume that each researcher has preferences over the research teams he would like to work in and over the student groups he would like to teach to. Correspondingly, each student has preferences over the groups of students he wants to study with and over the teams of researchers he would like to learn from. In this setup, we examine how the existence of core stable partitions on the distinct market sides, the restriction of agents’ preferences over groups to strict orderings, and the extent to which individual preferences respect common rankings shape the existence of core stable coalitional matchings.Coalitions, Common Rankings, Core, Stability, Totally Balanced Games, Two-Sided Matchings
Physical Layer Security: Coalitional Games for Distributed Cooperation
Cooperation between wireless network nodes is a promising technique for
improving the physical layer security of wireless transmission, in terms of
secrecy capacity, in the presence of multiple eavesdroppers. While existing
physical layer security literature answered the question "what are the
link-level secrecy capacity gains from cooperation?", this paper attempts to
answer the question of "how to achieve those gains in a practical decentralized
wireless network and in the presence of a secrecy capacity cost for information
exchange?". For this purpose, we model the physical layer security cooperation
problem as a coalitional game with non-transferable utility and propose a
distributed algorithm for coalition formation. Through the proposed algorithm,
the wireless users can autonomously cooperate and self-organize into disjoint
independent coalitions, while maximizing their secrecy capacity taking into
account the security costs during information exchange. We analyze the
resulting coalitional structures, discuss their properties, and study how the
users can self-adapt the network topology to environmental changes such as
mobility. Simulation results show that the proposed algorithm allows the users
to cooperate and self-organize while improving the average secrecy capacity per
user up to 25.32% relative to the non-cooperative case.Comment: Best paper Award at Wiopt 200
Non-centralized Control for Flow-based Distribution Networks: A Game-theoretical Insight
This paper solves a data-driven control problem for a flow-based distribution network with two objectives: a resource allocation and a fair distribution of costs. These objectives represent both cooperation and competition directions. It is proposed a solution that combines either a centralized or distributed cooperative game approach using the Shapley value to determine
a proper partitioning of the system and a fair communication cost distribution. On the other hand, a decentralized noncooperative game approach computing the Nash equilibrium is used to achieve the control objective of the resource allocation under a non-complete information topology. Furthermore, an invariant-set property is presented and the closed-loop system stability is analyzed for the non cooperative game approach. Another contribution regarding the cooperative game approach is an alternative way to compute the Shapley value for the proposed specific characteristic function. Unlike the classical
cooperative-games approach, which has a limited application due to the combinatorial explosion issues, the alternative method allows calculating the Shapley value in polynomial time and hence can be applied to large-scale problems.Generalitat de Catalunya FI 2014Ministerio de Ciencia y Educación DPI2016-76493-C3-3-RMinisterio de Ciencia y Educación DPI2008-05818Proyecto europeo FP7-ICT DYMASO
Coalitions in Cooperative Wireless Networks
Cooperation between rational users in wireless networks is studied using
coalitional game theory. Using the rate achieved by a user as its utility, it
is shown that the stable coalition structure, i.e., set of coalitions from
which users have no incentives to defect, depends on the manner in which the
rate gains are apportioned among the cooperating users. Specifically, the
stability of the grand coalition (GC), i.e., the coalition of all users, is
studied. Transmitter and receiver cooperation in an interference channel (IC)
are studied as illustrative cooperative models to determine the stable
coalitions for both flexible (transferable) and fixed (non-transferable)
apportioning schemes. It is shown that the stable sum-rate optimal coalition
when only receivers cooperate by jointly decoding (transferable) is the GC. The
stability of the GC depends on the detector when receivers cooperate using
linear multiuser detectors (non-transferable). Transmitter cooperation is
studied assuming that all receivers cooperate perfectly and that users outside
a coalition act as jammers. The stability of the GC is studied for both the
case of perfectly cooperating transmitters (transferrable) and under a partial
decode-and-forward strategy (non-transferable). In both cases, the stability is
shown to depend on the channel gains and the transmitter jamming strengths.Comment: To appear in the IEEE Journal on Selected Areas in Communication,
Special Issue on Game Theory in Communication Systems, 200
Spectrum Leasing as an Incentive towards Uplink Macrocell and Femtocell Cooperation
The concept of femtocell access points underlaying existing communication
infrastructure has recently emerged as a key technology that can significantly
improve the coverage and performance of next-generation wireless networks. In
this paper, we propose a framework for macrocell-femtocell cooperation under a
closed access policy, in which a femtocell user may act as a relay for
macrocell users. In return, each cooperative macrocell user grants the
femtocell user a fraction of its superframe. We formulate a coalitional game
with macrocell and femtocell users being the players, which can take individual
and distributed decisions on whether to cooperate or not, while maximizing a
utility function that captures the cooperative gains, in terms of throughput
and delay.We show that the network can selforganize into a partition composed
of disjoint coalitions which constitutes the recursive core of the game
representing a key solution concept for coalition formation games in partition
form. Simulation results show that the proposed coalition formation algorithm
yields significant gains in terms of average rate per macrocell user, reaching
up to 239%, relative to the non-cooperative case. Moreover, the proposed
approach shows an improvement in terms of femtocell users' rate of up to 21%
when compared to the traditional closed access policy.Comment: 29 pages, 11 figures, accepted at the IEEE JSAC on Femtocell Network
A Distributed Merge and Split Algorithm for Fair Cooperation in Wireless Networks
This paper introduces a novel concept from coalitional game theory which
allows the dynamic formation of coalitions among wireless nodes. A simple and
distributed merge and split algorithm for coalition formation is constructed.
This algorithm is applied to study the gains resulting from the cooperation
among single antenna transmitters for virtual MIMO formation. The aim is to
find an ultimate transmitters coalition structure that allows cooperating users
to maximize their utilities while accounting for the cost of coalition
formation. Through this novel game theoretical framework, the wireless network
transmitters are able to self-organize and form a structured network composed
of disjoint stable coalitions. Simulation results show that the proposed
algorithm can improve the average individual user utility by 26.4% as well as
cope with the mobility of the distributed users.Comment: This paper is accepted for publication at the IEEE ICC Workshop on
Cooperative Communications and Networkin
Coalitional Games for Distributed Collaborative Spectrum Sensing in Cognitive Radio Networks
Collaborative spectrum sensing among secondary users (SUs) in cognitive
networks is shown to yield a significant performance improvement. However,
there exists an inherent trade off between the gains in terms of probability of
detection of the primary user (PU) and the costs in terms of false alarm
probability. In this paper, we study the impact of this trade off on the
topology and the dynamics of a network of SUs seeking to reduce the
interference on the PU through collaborative sensing. Moreover, while existing
literature mainly focused on centralized solutions for collaborative sensing,
we propose distributed collaboration strategies through game theory. We model
the problem as a non-transferable coalitional game, and propose a distributed
algorithm for coalition formation through simple merge and split rules. Through
the proposed algorithm, SUs can autonomously collaborate and self-organize into
disjoint independent coalitions, while maximizing their detection probability
taking into account the cooperation costs (in terms of false alarm). We study
the stability of the resulting network structure, and show that a maximum
number of SUs per formed coalition exists for the proposed utility model.
Simulation results show that the proposed algorithm allows a reduction of up to
86.6% of the average missing probability per SU (probability of missing the
detection of the PU) relative to the non-cooperative case, while maintaining a
certain false alarm level. In addition, through simulations, we compare the
performance of the proposed distributed solution with respect to an optimal
centralized solution that minimizes the average missing probability per SU.
Finally, the results also show how the proposed algorithm autonomously adapts
the network topology to environmental changes such as mobility.Comment: in proceedings of IEEE INFOCOM 200
Coalition formation in simple games: The semistrict core
We consider the class of proper monotonic simple games and study coalition formation when an exogenous share vector and a solution concept are combined to guide the distribution of coalitional worth. Using a multiplicative composite solution, we induce players' preferences over coalitions in a hedonic game, and present conditions under which the semistrict core of the game is nonempty.coalition formation, semistrict core, simple games, winning coalitions
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