35,820 research outputs found
Fundamental structures of dynamic social networks
Social systems are in a constant state of flux with dynamics spanning from
minute-by-minute changes to patterns present on the timescale of years.
Accurate models of social dynamics are important for understanding spreading of
influence or diseases, formation of friendships, and the productivity of teams.
While there has been much progress on understanding complex networks over the
past decade, little is known about the regularities governing the
micro-dynamics of social networks. Here we explore the dynamic social network
of a densely-connected population of approximately 1000 individuals and their
interactions in the network of real-world person-to-person proximity measured
via Bluetooth, as well as their telecommunication networks, online social media
contacts, geo-location, and demographic data. These high-resolution data allow
us to observe social groups directly, rendering community detection
unnecessary. Starting from 5-minute time slices we uncover dynamic social
structures expressed on multiple timescales. On the hourly timescale, we find
that gatherings are fluid, with members coming and going, but organized via a
stable core of individuals. Each core represents a social context. Cores
exhibit a pattern of recurring meetings across weeks and months, each with
varying degrees of regularity. Taken together, these findings provide a
powerful simplification of the social network, where cores represent
fundamental structures expressed with strong temporal and spatial regularity.
Using this framework, we explore the complex interplay between social and
geospatial behavior, documenting how the formation of cores are preceded by
coordination behavior in the communication networks, and demonstrating that
social behavior can be predicted with high precision.Comment: Main Manuscript: 16 pages, 4 figures. Supplementary Information: 39
pages, 34 figure
Large-Scale Distributed Internet-based Discovery Mechanism for Dynamic Spectrum Allocation
Scarcity of frequencies and the demand for more bandwidth is likely to
increase the need for devices that utilize the available frequencies more
efficiently. Radios must be able to dynamically find other users of the
frequency bands and adapt so that they are not interfered, even if they use
different radio protocols. As transmitters far away may cause as much
interference as a transmitter located nearby, this mechanism can not be based
on location alone. Central databases can be used for this purpose, but require
expensive infrastructure and planning to scale. In this paper, we propose a
decentralized protocol and architecture for discovering radio devices over the
Internet. The protocol has low resource requirements, making it suitable for
implementation on limited platforms. We evaluate the protocol through
simulation in network topologies with up to 2.3 million nodes, including
topologies generated from population patterns in Norway. The protocol has also
been implemented as proof-of-concept in real Wi-Fi routers.Comment: Accepted for publication at IEEE DySPAN 201
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