4,093 research outputs found
Cloud Compute-and-Forward with Relay Cooperation
We study a cloud network with M distributed receiving antennas and L users,
which transmit their messages towards a centralized decoder (CD), where M>=L.
We consider that the cloud network applies the Compute-and-Forward (C&F)
protocol, where L antennas/relays are selected to decode integer equations of
the transmitted messages. In this work, we focus on the best relay selection
and the optimization of the Physical-Layer Network Coding (PNC) at the relays,
aiming at the throughput maximization of the network. Existing literature
optimizes PNC with respect to the maximization of the minimum rate among users.
The proposed strategy maximizes the sum rate of the users allowing nonsymmetric
rates, while the optimal solution is explored with the aid of the Pareto
frontier. The problem of relay selection is matched to a coalition formation
game, where the relays and the CD cooperate in order to maximize their profit.
Efficient coalition formation algorithms are proposed, which perform joint
relay selection and PNC optimization. Simulation results show that a
considerable improvement is achieved compared to existing results, both in
terms of the network sum rate and the players' profits.Comment: Submitted to IEEE Transactions on Wireless Communication
Signal-Aligned Network Coding in K-User MIMO Interference Channels with Limited Receiver Cooperation
In this paper, we propose a signal-aligned network coding (SNC) scheme for
K-user time-varying multiple-input multiple-output (MIMO) interference channels
with limited receiver cooperation. We assume that the receivers are connected
to a central processor via wired cooperation links with individual limited
capacities. Our SNC scheme determines the precoding matrices of the
transmitters so that the transmitted signals are aligned at each receiver. The
aligned signals are then decoded into noiseless integer combinations of
messages, also known as network-coded messages, by physical-layer network
coding. The key idea of our scheme is to ensure that independent integer
combinations of messages can be decoded at the receivers. Hence the central
processor can recover the original messages of the transmitters by solving the
linearly independent equations. We prove that our SNC scheme achieves full
degrees of freedom (DoF) by utilizing signal alignment and physical-layer
network coding. Simulation results show that our SNC scheme outperforms the
compute-and-forward scheme in the finite SNR regime of the two-user and the
three-user cases. The performance improvement of our SNC scheme mainly comes
from efficient utilization of the signal subspaces for conveying independent
linear equations of messages to the central processor.Comment: 12 pages, 4 figures, submitted to the IEEE Transactions on Vehicular
Technolog
Applications of Repeated Games in Wireless Networks: A Survey
A repeated game is an effective tool to model interactions and conflicts for
players aiming to achieve their objectives in a long-term basis. Contrary to
static noncooperative games that model an interaction among players in only one
period, in repeated games, interactions of players repeat for multiple periods;
and thus the players become aware of other players' past behaviors and their
future benefits, and will adapt their behavior accordingly. In wireless
networks, conflicts among wireless nodes can lead to selfish behaviors,
resulting in poor network performances and detrimental individual payoffs. In
this paper, we survey the applications of repeated games in different wireless
networks. The main goal is to demonstrate the use of repeated games to
encourage wireless nodes to cooperate, thereby improving network performances
and avoiding network disruption due to selfish behaviors. Furthermore, various
problems in wireless networks and variations of repeated game models together
with the corresponding solutions are discussed in this survey. Finally, we
outline some open issues and future research directions.Comment: 32 pages, 15 figures, 5 tables, 168 reference
Joint Computation and Communication Cooperation for Mobile Edge Computing
This paper proposes a novel joint computation and communication cooperation
approach in mobile edge computing (MEC) systems, which enables user cooperation
in both computation and communication for improving the MEC performance. In
particular, we consider a basic three-node MEC system that consists of a user
node, a helper node, and an access point (AP) node attached with an MEC server.
We focus on the user's latency-constrained computation over a finite block, and
develop a four-slot protocol for implementing the joint computation and
communication cooperation. Under this setup, we jointly optimize the
computation and communication resource allocation at both the user and the
helper, so as to minimize their total energy consumption subject to the user's
computation latency constraint. We provide the optimal solution to this
problem. Numerical results show that the proposed joint cooperation approach
significantly improves the computation capacity and the energy efficiency at
the user and helper nodes, as compared to other benchmark schemes without such
a joint design.Comment: 8 pages, 4 figure
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