researResearch - Télécom Bretagne

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researResearch
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Projects associated with
the PERDYN platform:
Two model optical access networks, in GEPON
and GPON technologies respectively, were set up
and evaluated. Working in collaboration with the
Computer Science Department of Telecom
Bretagne to analyse the traffic in these networks
and after detailed characterisations of the
existing prototype, an analysis of the solutions
enabling integration of an OSNR in-band
measure of the WDM canals was undertaken and
early experimental results were obtained.
Launch of the CapilR platform:
The need for digital irrigation via the numerous
access points has led to the creation of a new
speciality: network fringe engineering. The
emergence of new skills and services will lead to
the creation of a synergy of different
technological domains and their integration into
a global vision of the network. This new
development will lead to the selection of
technologies that are adapted to the different
field configurations and services, providing
companies with the capacity to exploit existing
infrastructure in order to deliver new forms of
content and services to the end user. In France,
today, such integrated skills are lacking. Our
mission is to optimise the exploitation of existing
infrastructures (e.g. bus, Metro, taxi, etc) in order
to offer new services. This constitutes an original
and coherent offer, integrating, as it does, optical
technologies and radio frequencies, for the
deployment of mobile networks in high-density
environments. Depending on the needs, this will
bring expertise, engineering advice, as well as an
evaluation of the technologies proposed by
selected equipment suppliers. This initiative is
being pursued in close collaboration with the
Microwaves Department of Telecom Bretagne
and the RESO laboratory of the ENIB.
Thoughts on the issue of optical
distribution within the home
network:
Optical fibres, being the backbone of
telecommunications transport networks, have
been incorporated into the access network in
order to propose broadband solutions (100
Mbit/s) to subscribers in urban areas. For
domestic use, infra-red transmission is a
classical solution to enable audio-video devices,
mobile phones or portable computers to
intercommunicate. It remains limited, however,
to modest coverage and data rates (a few
hundreds of kbits/s). Faced with the growing
need for high speed data rates and considering
the existing “radio” solutions which are subject
to constraints in terms of power and spectral
resources, optical transmission in indoor free
space areas (IFSO) is envisaged for the medium
term. It offers significant advantages: increased
broadband transmission rates in theory, natural
connectivity to an optical access network, no
spectral rules and no interference from or with
other domestic devices. The IFSO propagation
modes can be classified into two types, namely,
direct view and diffuse mode. At an intuitive level,
the diffuse mode maximises receiver mobility
and connection reliability, but the significant
losses encountered necessitate high-powered
transmission levels, since the maximum canal
rate is limited by the reception of multiple paths.
In contrast, the LOS mode provides higher data
rates (several tens of Gbit/s) but requires precise
alignment to and tracking of the transmitter in
comparison to the receiver, as mobility is
disturbed by the presence of obstacles. The
challenge to be met, therefore, is the following:
maximise the signal-to-noise ratio at reception
while respecting eye-safety standards and, at the
same time, developing a domestic multiple
access topology which ensures connectivity,
mobility and high broadband rates between
users. In this context, we have been studying LOS
optical connection systems based on dynamic
deflectors enabling optimised tracking and
visibility.
To build flexible optical home networks,
interconnecting the different access points
(optical micro-cells) with short to mid-range
(from 5 to 100m) polymer optical fibre (POF)
sections is envisaged and which, potentially,
would reduce the global energy cost of the
system. This initiative is being developed in
collaboration with the Signals and
Communications Department of Telecom
Bretagne.