17,553 research outputs found
Power Allocation Games on Interference Channels with Complete and Partial Information
We consider a wireless channel shared by multiple transmitter-receiver pairs.
Their transmissions interfere with each other. Each transmitter-receiver pair
aims to maximize its long-term average transmission rate subject to an average
power constraint. This scenario is modeled as a stochastic game under different
assumptions. We first assume that each transmitter and receiver has knowledge
of all direct and cross link channel gains. We later relax the assumption to
the knowledge of incident channel gains and then further relax to the knowledge
of the direct link channel gains only. In all the cases, we formulate the
problem of finding the Nash equilibrium as a variational inequality (VI)
problem and present an algorithm to solve the VI.Comment: arXiv admin note: text overlap with arXiv:1409.755
Optimal Linear Precoding Strategies for Wideband Non-Cooperative Systems based on Game Theory-Part I: Nash Equilibria
In this two-parts paper we propose a decentralized strategy, based on a
game-theoretic formulation, to find out the optimal precoding/multiplexing
matrices for a multipoint-to-multipoint communication system composed of a set
of wideband links sharing the same physical resources, i.e., time and
bandwidth. We assume, as optimality criterion, the achievement of a Nash
equilibrium and consider two alternative optimization problems: 1) the
competitive maximization of mutual information on each link, given constraints
on the transmit power and on the spectral mask imposed by the radio spectrum
regulatory bodies; and 2) the competitive maximization of the transmission
rate, using finite order constellations, under the same constraints as above,
plus a constraint on the average error probability. In Part I of the paper, we
start by showing that the solution set of both noncooperative games is always
nonempty and contains only pure strategies. Then, we prove that the optimal
precoding/multiplexing scheme for both games leads to a channel diagonalizing
structure, so that both matrix-valued problems can be recast in a simpler
unified vector power control game, with no performance penalty. Thus, we study
this simpler game and derive sufficient conditions ensuring the uniqueness of
the Nash equilibrium. Interestingly, although derived under stronger
constraints, incorporating for example spectral mask constraints, our
uniqueness conditions have broader validity than previously known conditions.
Finally, we assess the goodness of the proposed decentralized strategy by
comparing its performance with the performance of a Pareto-optimal centralized
scheme. To reach the Nash equilibria of the game, in Part II, we propose
alternative distributed algorithms, along with their convergence conditions.Comment: Paper submitted to IEEE Transactions on Signal Processing, September
22, 2005. Revised March 14, 2007. Accepted June 5, 2007. To be published on
IEEE Transactions on Signal Processing, 2007. To appear on IEEE Transactions
on Signal Processing, 200
Improving Macrocell - Small Cell Coexistence through Adaptive Interference Draining
The deployment of underlay small base stations (SBSs) is expected to
significantly boost the spectrum efficiency and the coverage of next-generation
cellular networks. However, the coexistence of SBSs underlaid to an existing
macro-cellular network faces important challenges, notably in terms of spectrum
sharing and interference management. In this paper, we propose a novel
game-theoretic model that enables the SBSs to optimize their transmission rates
by making decisions on the resource occupation jointly in the frequency and
spatial domains. This procedure, known as interference draining, is performed
among cooperative SBSs and allows to drastically reduce the interference
experienced by both macro- and small cell users. At the macrocell side, we
consider a modified water-filling policy for the power allocation that allows
each macrocell user (MUE) to focus the transmissions on the degrees of freedom
over which the MUE experiences the best channel and interference conditions.
This approach not only represents an effective way to decrease the received
interference at the MUEs but also grants the SBSs tier additional transmission
opportunities and allows for a more agile interference management. Simulation
results show that the proposed approach yields significant gains at both
macrocell and small cell tiers, in terms of average achievable rate per user,
reaching up to 37%, relative to the non-cooperative case, for a network with
150 MUEs and 200 SBSs
Markov Decision Processes with Applications in Wireless Sensor Networks: A Survey
Wireless sensor networks (WSNs) consist of autonomous and resource-limited
devices. The devices cooperate to monitor one or more physical phenomena within
an area of interest. WSNs operate as stochastic systems because of randomness
in the monitored environments. For long service time and low maintenance cost,
WSNs require adaptive and robust methods to address data exchange, topology
formulation, resource and power optimization, sensing coverage and object
detection, and security challenges. In these problems, sensor nodes are to make
optimized decisions from a set of accessible strategies to achieve design
goals. This survey reviews numerous applications of the Markov decision process
(MDP) framework, a powerful decision-making tool to develop adaptive algorithms
and protocols for WSNs. Furthermore, various solution methods are discussed and
compared to serve as a guide for using MDPs in WSNs
Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey
This paper provides a comprehensive review of the domain of physical layer
security in multiuser wireless networks. The essential premise of
physical-layer security is to enable the exchange of confidential messages over
a wireless medium in the presence of unauthorized eavesdroppers without relying
on higher-layer encryption. This can be achieved primarily in two ways: without
the need for a secret key by intelligently designing transmit coding
strategies, or by exploiting the wireless communication medium to develop
secret keys over public channels. The survey begins with an overview of the
foundations dating back to the pioneering work of Shannon and Wyner on
information-theoretic security. We then describe the evolution of secure
transmission strategies from point-to-point channels to multiple-antenna
systems, followed by generalizations to multiuser broadcast, multiple-access,
interference, and relay networks. Secret-key generation and establishment
protocols based on physical layer mechanisms are subsequently covered.
Approaches for secrecy based on channel coding design are then examined, along
with a description of inter-disciplinary approaches based on game theory and
stochastic geometry. The associated problem of physical-layer message
authentication is also introduced briefly. The survey concludes with
observations on potential research directions in this area.Comment: 23 pages, 10 figures, 303 refs. arXiv admin note: text overlap with
arXiv:1303.1609 by other authors. IEEE Communications Surveys and Tutorials,
201
Energy-Efficient Resource Allocation in Multiuser MIMO Systems: A Game-Theoretic Framework
This paper focuses on the cross-layer issue of resource allocation for energy
efficiency in the uplink of a multiuser MIMO wireless communication system.
Assuming that all of the transmitters and the uplink receiver are equipped with
multiple antennas, the situation considered is that in which each terminal is
allowed to vary its transmit power, beamforming vector, and uplink receiver in
order to maximize its own utility, which is defined as the ratio of data
throughput to transmit power; the case in which non-linear interference
cancellation is used at the receiver is also investigated. Applying a
game-theoretic formulation, several non-cooperative games for utility
maximization are thus formulated, and their performance is compared in terms of
achieved average utility, achieved average SINR and average transmit power at
the Nash equilibrium. Numerical results show that the use of the proposed
cross-layer resource allocation policies brings remarkable advantages to the
network performance.Comment: Proceedings of the 16th European Signal Processing Conference,
Lausanne, Switzerland, August 25-29, 200
Competition in Wireless Systems via Bayesian Interference Games
We study competition between wireless devices with incomplete information
about their opponents. We model such interactions as Bayesian interference
games. Each wireless device selects a power profile over the entire available
bandwidth to maximize its data rate. Such competitive models represent
situations in which several wireless devices share spectrum without any central
authority or coordinated protocol.
In contrast to games where devices have complete information about their
opponents, we consider scenarios where the devices are unaware of the
interference they cause to other devices. Such games, which are modeled as
Bayesian games, can exhibit significantly different equilibria. We first
consider a simple scenario of simultaneous move games, where we show that the
unique Bayes-Nash equilibrium is where both devices spread their power equally
across the entire bandwidth. We then extend this model to a two-tiered spectrum
sharing case where users act sequentially. Here one of the devices, called the
primary user, is the owner of the spectrum and it selects its power profile
first. The second device (called the secondary user) then responds by choosing
a power profile to maximize its Shannon capacity. In such sequential move
games, we show that there exist equilibria in which the primary user obtains a
higher data rate by using only a part of the bandwidth.
In a repeated Bayesian interference game, we show the existence of reputation
effects: an informed primary user can bluff to prevent spectrum usage by a
secondary user who suffers from lack of information about the channel gains.
The resulting equilibrium can be highly inefficient, suggesting that
competitive spectrum sharing is highly suboptimal.Comment: 30 pages, 3 figure
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