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ITU-T Study Group 15 List of Questions Under Study (Study Period 2005-2008) |
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ITU-T SG 15 Question 6/15 |
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Characteristics of optical systems for terrestrial transport networks (Continuation of Question 16/15)
- Motivation
Optical fibre networks are deployed in telecommunication systems worldwide.
Structural reforms leading to increased privatisation of telecommunications
networks create an operating environment requiring optical networking and
interconnection among different carriers. Simultaneously, there is occurring a
rapid evolution toward a packet-based (IP type) infrastructure and a future
Next Generation Network (NGN) supporting multiple integrated services. These
developments are being fuelled by customer demand for ever higher bit rate
data services, high-speed Internet access, and other innovative services.
It leads to a push for higher bit-rate (Terabit/s) optical transport systems
in the intra-office, inter-office and long distance networks of the various
network operators.
Together with the increasing use of the Synchronous Digital Hierarchy (SDH)
worldwide, there is now an interest by network operators to deploy an Optical
Transport Network (OTN). The OTN utilises the technologies of time-division
multiplexing (TDM) and Wavelength-Division Multiplexing (WDM); new technologies
such as Optical Time Division Multiplexing (OTDM) may be expected in the future.
Specifications are needed for physical layer interfaces of OTDM and WDM systems,
including the OTN, to enable the evolution of the intra-office, inter-office
and long distance networks to support the ubiquitous availability of next-generation
high-bandwidth services. To the greatest extent possible, these specifications
should enable transverse compatibility in a multi-vendor, multi-network-operator environment.
The following major Recommendations, in force at the time of approval of this
Question, fall under its responsibility: G.664, G.955, G.957, G.959.1, G.691,
G.692, G.693, G.694-series, G.695, G.697.
- Question
- What system aspects and physical layer characteristics are
necessary to enable longitudinally compatible and transversely
compatible optical systems in intra-office, inter-office and
long distance networks, including evolution to the OTN?
- What enhancements to existing draft or published Recommendations
and what new Recommendations are necessary to specify interfaces
for single and multichannel optical transport systems for bit rates
up to or above 40 Gbit/s?
- What systems and physical layer considerations are necessary
for optical transport systems optimized for packet data transport
(e.g. IP over WDM) and NGN applications?
- What enhancements should be made to existing draft or published
Recommendations to reflect technological developments?
Study items to be considered include, but are not limited to:
- General considerations for optical systems used to transport
SDH, OTN, Ethernet and PDH signals using several types of single-mode fibre
- Statistical and semi-statistical power budget approaches
- Optical link and optical interface parameters for SDH and
OTN systems to enable transverse compatibility
- Optical frequency plan, including optical supervisory
channel wavelength, for WDM systems
- Optical aspects of TDM and WDM systems such as:
- Optical power levels including safety aspects and automatic gain control
- Dispersion accommodation techniques
- Polarisation mode dispersion system penalty
- Clarification and resolution of technical issues in current and draft Recommendations
- Specifications to enable transverse compatibility in single-channel and multichannel optical systems
- System models, reference configurations and reference points to support alternative optical interface specification methodologies
- Descriptive methodology for classifying application code structures of optical interfaces to be standardised (e.g. increasingly complicated systems with various dispersion accommodation techniques, line codes, etc.)
- Characteristics of TDM line systems up to or above 40 Gbit/s and their upgrade by WDM
- Optical interface specifications for metro applications
- Optical interface specifications for long haul multi-span applications
- Utilisation of Optical Add-Drop Multiplexers (OADMs) and Optical cross-Connects (OXCs) with or without wavelength converter, also considering evolution towards transversely compatible interfaces for an All Optical Network (AON)
- Concatenation of the transfer functions of different optical Network Elements (NEs)
- Application of forward error correction (FEC) techniques to terrestrial optical transmission systems (e.g. to enhance system margin or to relax optical parameter specifications)
- Optical systems using alternative line codes (e.g. dispersion-supported Return-to-Zero (RZ) or soliton-type techniques)
- Use of new types of optical amplifiers with changes in systems wavelengths and/or power levels
- Application of additional passive and active dispersion accommodation techniques (e.g. adaptive chromatic dispersion compensators)
- Single and Multichannel Polarization Mode Dispersion (PMD) compensation in optical systems
- Application of electronic compensation and equalization techniques
- Enhanced statistical design approaches
- Characteristics of optical systems optimized for data transport, e.g. IP, SDH, ATM and Ethernet over an OTN
- Parameters for optical monitoring
- Availability/reliability aspects of optical systems
- Tasks
Tasks include, but are not limited to:
- Enhance Recommendations G.664, G.693, G.695, and G.959.1
- Develop new Recommendations or combine existing Recommendations
from progress on the above study points
Note: An up-to-date status of work under this Question is contained in the
SG 15 Work Programme.
- Relationships
- Recommendations:
- G.65x series, G.66x series, G.671
- Questions:
- Q2/15, Q3/15, Q5/15, Q7/15, Q8/15, Q9/15, Q11/15, Q12/15 and Q16/9
- Study Groups:
- ITU-T SG 13 on NGN, data-centric networks, and network performance objectives
- Standardization bodies, forums and consortia:
- IEC SC86C on system measurement test methods and on optical amplifier test methods
- OIF on optical systems interfaces
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