Optical time division
multiplexing-OTDM
Since the speed
at which electrical signal can modulate optical carriers is limited,
to fully exploit the optical fiber bandwidth, another optical
multiplexing technique is OTDM.
Optical TDM
attempts to copy conventional TDM ideas and realize them optically,
thereby achieving much higher speeds (Fig. 8). To overcome the
bit-rate limitation imposed by electronics within a single
wavelength bandwidth, OTDM techniques using narrow optical pulse
laser sources have been developed. Since the approach uses extremely
narrow optical timeslots with correspondingly large bandwidths, a
natural increase in the data rates (40 Gb/s–100 Gb/s or higher) at a
single wavelength bandwidth, is obtained by multiplexing low bit
rate tributary data streams directly in the optical domain. To
further increase the capacity, a combination of OTDM with WDM have
been developed as follows:
· 7
wavelengths x200 Gb/s (1.4 Tb/s) transmitted through 50 km of
dispersion shifted fiber;
· 25 wavelengths x40 Gb/s (1 Tb/s) transmitted over 342 km;
· 19 wavelengths x100 Gb/s (3 Tb/s) transmitted over 40 km of
dispersion shifted fiber using supercontinuum WDM sources.
OTDM has features
that make it very attractive as a future network technology:
· Simple
access to high aggregate line rates (100 Gb/s and higher)
· Tributary data rates at any desired degree of granularity and
compatible with existing technologies such as SDH
· Greatly simplified amplifier and dispersion management (due to
single wavelength transmission)
· Network nodes that require electronics operating at the local
data rate only.
Physical
topologies that can be considered in OTDM are point-to-point, star,
and ring.
The main elements
in OTDM (sub) system are:
1. optical
pulse source
2. optical multiplexer
3. optical demultiplexer.
Realization of
OTDM ring networks requires OTDM add-drop multiplexers at each
station on the ring.
Figure 8 -
Point-to-Point transmission system using OTDM. MSSI (mid-span
spectral inversion)
The technology
involved in the implementation of OTDM is very different from that
of WDM. Most of the devices required to implement OTDMA are still
confined to the laboratory. In addition, OTDMA has still a number of
difficult hurdles to solve such as synchronization and the immature
technology of selecting one channel out of multiplexed picosecond
optical pulse data streams. Hence, scope for evolving new innovative
methods exists in order to determine the best trade-off regarding
capacity, performance, flexibility and complexity of a variety of
approaches to network provision.
About TACS
TACS
Consulting Delivers The Insight and Vision on Information
Communication and Energy Technologies for Strategic Decisions.
TACS is Pioneer and Innovator of many Communication Signal
Processors, Optical Modems, Optimum or Robust Multi-User or
Single-User MIMO Packet Radio Modems, 1G Modems, 2G Modems, 3G
Modems, 4G Modems, 5G Modems, 6G Modems, Satellite Modems, PSTN
Modems, Cable Modems, PLC Modems, IoT Modems and more..
TACS consultants conducted fundamental scientific research in
the field of communications and are the pioneer and first
inventors of PLC MODEMS, Optimum or Robust Multi-User or
Single-User MIMO fixed or mobile packet radio structures in the
world.
TACS is a leading top consultancy in the field of Information,
Communication and Energy Technologies (ICET). The heart of our
Consulting spectrum comprises strategic, organizational, and
technology-intensive tasks that arise from the use of new
information and telecommunications technologies. TACS Consulting
offers Strategic Planning, Information, Communications and
Energy Technology Standards and Architecture Assessment, Systems
Engineering, Planning, and Resource Optimization.
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TACS is a leading top consultancy in the field of information, communication
and energy technologies (ICET).
The heart of our consulting spectrum comprises strategic,
organizational, and technology-intensive tasks that arise from the use of new
information, communication and energy technologies.
The major emphasis in our work is found in innovative consulting and
implementation solutions which result from the use of modern information,
communication and energy technologies.
TACS
- Delivers the insight and vision
on technology for strategic decisions
- Drives
innovations forward as part of our service offerings to customers
worldwide
- Conceives
integral solutions on the basis of our integrated business and technological
competence in the ICET sector
- Assesses technologies and standards and develops
architectures for fixed or mobile, wired or wireless communications systems
and networks
- Provides
the energy and experience of world-wide leading innovators and experts in their fields for local,
national or large-scale international projects.
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