Frequency assignment in mobile and radio networks
Πάντζιου, Γραμματή Ε.
Τεχνολογικό Εκπαιδευτικό Ίδρυμα Αθήνας. Σχολή Τεχνολογικών Εφαρμογών. Τμήμα Μηχανικών Πληροφορικής Τ.Ε.
We deal with the problem of frequency assignment in mobile and
general radio networks, where the signal interferences are modeled using an
interference graph G. Our approach uses graph theoretic and optimization
techniques. We rst study on-line algorithms for frequency assignment in mobile
networks. We prove that the greedy algorithm is -competitive, where
is the maximum degree of G. We next employ the \classify and randomly
select" paradigm to give a 5-competitive randomized algorithm for the case of
planar interference graphs. We also show how the problem of on-line frequency
assignment in mobile networks with multiple available frequency channels reduces
to the problem of on-line frequency assignment in mobile networks with
a single channel.
We continue to study radio coloring and radio labeling as combinatorial
models for frequency assignment in general radio networks. In both problems,
the ob jective is to minimize the maximum frequency channel used, while the
transmitters being adjacent in the interference graph must be assigned channels
that di er by at least two from each other. In radio coloring, di erent channels
must be assigned to transmitters that are at distance two in the interference
graph. Additionally, in radio labeling, all the transmitters must be assigned
distinct frequency channels. Radio labelling is shown to be equivalent to a
generalization of Hamiltonian path, and both problems remain N P -complete,
even if they restricted to graphs of diameter two. We nally present algorithms
and lower bounds for two on-line variations of radio labeling.
Technological Educational Institute of Athens
DIMACS Series in Discrete Mathematics and Theoretical Computer Science