Towards a Platform for Widespread Embedded Intelligence - ERCIM

R&D AND TECHNOLOGY TRANSFER
Mobile Hybrid Wireless Networks
HyMN: A Self-Organizing System
for Interest-based Data Distribution
in Mobile Hybrid Wireless Networks
by Steffen Rothkugel, Matthias R. Brust, Adrian Andronache
The concept of self-organisation already exists in the realm of ad-hoc networks.
The inherent limitations of pure ad-hoc networks can be overcome by introducing
uplinks to the Internet backbone. Extending the principles of self-organisation
by transparently including those additional network links is the focus of the
HyWercs project. HyMN, in turn, is a system aimed at fostering user experience
by employing these concepts in the domain of multimedia content distribution.
Ad-hoc networks emphasise flexibility
and survivability of the whole system.
However, centralised approaches, for
example for group management and
information provisioning, do not work
well in such settings. Moreover, due to
frequent topology changes, connectivity
of devices cannot be generally
guaranteed. In particular, this makes it
hard to disseminate information in a
reliable way. We overcome these limitations
inherent to pure ad-hoc networks
by (a) establishing local groups
of communicating devices in a selforganising
manner and (b) introducing
dedicated uplinks to a backbone infrastructure.
Such uplinks are used for
accessing resources available on the
Internet. Additionally, they are
employed to directly interconnect distant
devices, either within a single partition
and particularly also across different
partitions. In practice, uplinks are
realised for instance using cellular networks,
satellites, or via Wi-Fi hotspots.
Consequently, ad-hoc networks with
devices that provide uplinks are called
hybrid wireless networks throughout
this paper.
One main goal of the HyWercs project is
to develop a middleware that enables
mobile devices to organise themselves in
order to optimise the data access and
provisioning process. The devices running
the middleware keep track of the
user's interests, which can be single data
items or topics that comprise several data
items. Devices sharing common interests
will join interest groups. Whenever there
is the need to retrieve information from a
backbone network - like the Internet - or
52 ERCIM News No. 67, October 2006
to establish a communication link to a
device in another network partition,
uplinks are employed. The mobile
devices elect a particular member of the
interest group, a so-called injection
point, which maintains the uplinks.
As one proof of concept, the HyMN
system (Hybrid Multimedia Network)
has been implemented prototypically on
top of the JANE1 simulation environment.
JANE is designed to support appli-
The HyMN System in simulation mode.
cation and protocol design in the realm
of ad-hoc networks. One distinct feature
of JANE is that applications can be executed
on top of simulated devices (see
figure) as well as in so-called platform
mode on real hardware.
HyMN is designed for users interested in
live multimedia news, for example from
certain sports events. Mobile devices of
football fans, for instance, create an
interest group in a local ad-hoc network
partition. Multiples of such groups coexist,
such as football fans in pubs, those
watching another match, traveling fans
and more. In each of these cases, a considerable
number of people have a
shared interest and might join forces in a
local setting.