6,875 research outputs found
Network Farthest-Point Diagrams
Consider the continuum of points along the edges of a network, i.e., an
undirected graph with positive edge weights. We measure distance between these
points in terms of the shortest path distance along the network, known as the
network distance. Within this metric space, we study farthest points.
We introduce network farthest-point diagrams, which capture how the farthest
points---and the distance to them---change as we traverse the network. We
preprocess a network G such that, when given a query point q on G, we can
quickly determine the farthest point(s) from q in G as well as the farthest
distance from q in G. Furthermore, we introduce a data structure supporting
queries for the parts of the network that are farther away from q than some
threshold R > 0, where R is part of the query.
We also introduce the minimum eccentricity feed-link problem defined as
follows. Given a network G with geometric edge weights and a point p that is
not on G, connect p to a point q on G with a straight line segment pq, called a
feed-link, such that the largest network distance from p to any point in the
resulting network is minimized. We solve the minimum eccentricity feed-link
problem using eccentricity diagrams. In addition, we provide a data structure
for the query version, where the network G is fixed and a query consists of the
point p.Comment: A preliminary version of this work was presented at the 24th Canadian
Conference on Computational Geometr
Power adjustment and scheduling in OFDMA femtocell networks
Densely-deployed femtocell networks are used to enhance wireless coverage in public spaces like office buildings, subways, and academic buildings. These networks can increase throughput for users, but edge users can suffer from co-channel interference, leading to service outages. This paper introduces a distributed algorithm for network configuration, called Radius Reduction and Scheduling (RRS), to improve the performance and fairness of the network. RRS determines cell sizes using a Voronoi-Laguerre framework, then schedules users using a scheduling algorithm that includes vacancy requests to increase fairness in dense femtocell networks. We prove that our algorithm always terminate in a finite time, producing a configuration that guarantees user or area coverage. Simulation results show a decrease in outage probability of up to 50%, as well as an increase in Jain's fairness index of almost 200%
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