Abstract: We study the problem of maintaining connectivity in a wireless
network where the network nodes are equipped with
directionalantennas. Nodes correspond to points on the
plane and each uses a directional antenna modeled by a sector
with a given angle and radius. The connectivity problem
is to decide whether or not it is possible to orient the antennas
so that the directed graph induced by the node transmissions
is strongly connected. We present algorithms for
simple polynomial-time-solvable cases of the problem, show
that the problem is NP-complete in the 2-dimensional case
when the sector angle is small, and present algorithms that
approximate the minimum radius to achieve connectivity for
sectors with a given angle. We also discuss several extensions
to related problems. To the best of our knowledge, the
problem has not been studied before in the literature.
Abstract: The ROTA project is aimed at offering high-speed network connections to ships traveling at archipelagos, i.e. seas with dense clusters of islands, such as the Aegean sea. The ROTA system is based on the use of directionalantennas on-board the ships and stationary antennas on the islands. The stationary antennas on the islands are connected to high-speed commercial computer networks, which are available on practically all inhabited islands at the Aegean sea, thus implementing a Virtual Private Network (VPN). This approach is much more cost-effective when compared to current approaches that rely on the usage of satellite communications. This paper presents the concept behind ROTA platform.