10,939 research outputs found
Exact algorithms to minimize interference in wireless sensor networks
AbstractFinding a low-interference connected topology is a fundamental problem in wireless sensor networks (WSNs). The problem of reducing interference through adjusting the nodes’ transmission radii in a connected network is one of the most well-known open algorithmic problems in wireless sensor network optimization. In this paper, we study minimization of the average interference and the maximum interference for the highway model, where all the nodes are arbitrarily distributed on a line. First, we prove that there is always an optimal topology with minimum interference that is planar. Then, two exact algorithms are proposed. The first one is an exact algorithm to minimize the average interference in polynomial time, O(n3Δ), where n is the number of nodes and Δ is the maximum node degree. The second one is an exact algorithm to minimize the maximum interference in sub-exponential time, O(n3ΔO(k)), where k=O(Δ) is the minimum maximum interference. All the optimal topologies constructed are planar
Joint Hybrid Backhaul and Access Links Design in Cloud-Radio Access Networks
The cloud-radio access network (CRAN) is expected to be the core network
architecture for next generation mobile radio systems. In this paper, we
consider the downlink of a CRAN formed of one central processor (the cloud) and
several base-station (BS), where each BS is connected to the cloud via either a
wireless or capacity-limited wireline backhaul link. The paper addresses the
joint design of the hybrid backhaul links (i.e., designing the wireline and
wireless backhaul connections from the cloud to the BSs) and the access links
(i.e., determining the sparse beamforming solution from the BSs to the users).
The paper formulates the hybrid backhaul and access link design problem by
minimizing the total network power consumption. The paper solves the problem
using a two-stage heuristic algorithm. At one stage, the sparse beamforming
solution is found using a weighted mixed `1=`2 norm minimization approach; the
correlation matrix of the quantization noise of the wireline backhaul links is
computed using the classical rate-distortion theory. At the second stage, the
transmit powers of the wireless backhaul links are found by solving a power
minimization problem subject to quality-of-service constraints, based on the
principle of conservation of rate by utilizing the rates found in the first
stage. Simulation results suggest that the performance of the proposed
algorithm approaches the global optimum solution, especially at high
signal-to-interference-plus-noise ratio (SINR).Comment: 6 pages, 3 figures, IWCPM 201
Interference Minimization in Asymmetric Sensor Networks
A fundamental problem in wireless sensor networks is to connect a given set
of sensors while minimizing the \emph{receiver interference}. This is modeled
as follows: each sensor node corresponds to a point in and each
\emph{transmission range} corresponds to a ball. The receiver interference of a
sensor node is defined as the number of transmission ranges it lies in. Our
goal is to choose transmission radii that minimize the maximum interference
while maintaining a strongly connected asymmetric communication graph.
For the two-dimensional case, we show that it is NP-complete to decide
whether one can achieve a receiver interference of at most . In the
one-dimensional case, we prove that there are optimal solutions with nontrivial
structural properties. These properties can be exploited to obtain an exact
algorithm that runs in quasi-polynomial time. This generalizes a result by Tan
et al. to the asymmetric case.Comment: 15 pages, 5 figure
Delay Reduction in Multi-Hop Device-to-Device Communication using Network Coding
This paper considers the problem of reducing the broadcast decoding delay of
wireless networks using instantly decodable network coding (IDNC) based
device-to-device (D2D) communications. In a D2D configuration, devices in the
network can help hasten the recovery of the lost packets of other devices in
their transmission range by sending network coded packets. Unlike previous
works that assumed fully connected network, this paper proposes a partially
connected configuration in which the decision should be made not only on the
packet combinations but also on the set of transmitting devices. First, the
different events occurring at each device are identified so as to derive an
expression for the probability distribution of the decoding delay. The joint
optimization problem over the set of transmitting devices and the packet
combinations of each is, then, formulated. The optimal solution of the joint
optimization problem is derived using a graph theory approach by introducing
the cooperation graph and reformulating the problem as a maximum weight clique
problem in which the weight of each vertex is the contribution of the device
identified by the vertex. Through extensive simulations, the decoding delay
experienced by all devices in the Point to Multi-Point (PMP) configuration, the
fully connected D2D (FC-D2D) configuration and the more practical partially
connected D2D (PC-D2D) configuration are compared. Numerical results suggest
that the PC-D2D outperforms the FC-D2D and provides appreciable gain especially
for poorly connected networks
Interference Alignment via Message-Passing
We introduce an iterative solution to the problem of interference alignment
(IA) over MIMO channels based on a message-passing formulation. We propose a
parameterization of the messages that enables the computation of IA precoders
by a min-sum algorithm over continuous variable spaces -- under this
parameterization, suitable approximations of the messages can be computed in
closed-form. We show that the iterative leakage minimization algorithm of
Cadambe et al. is a special case of our message-passing algorithm, obtained for
a particular schedule. Finally, we show that the proposed algorithm compares
favorably to iterative leakage minimization in terms of convergence speed, and
discuss a distributed implementation.Comment: Submitted to the IEEE International Conference on Communications
(ICC) 201
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