1、 International Telecommunication Union ITU-T G.667TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (12/2006) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Transmission media and optical systems characteristics Characteristics of optical components and subsystems Characteristi
2、cs of adaptive chromatic dispersion compensators ITU-T Recommendation G.667 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYST
3、EMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND
4、 LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 General G.600G.609 Symmetric cable pairs G.610G.619 Land coaxial cable pairs G.620G.629 Submarine cables G.630G.639 Free space optical systems G.640G.649 Optical fibre cables G.650G.659 Characteristics of op
5、tical components and subsystems G.660G.679 Characteristics of optical systems G.680G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSIO
6、N MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.667 (12/2006) i ITU-T Recommendation G.667 Characteristics
7、 of adaptive chromatic dispersion compensators Summary ITU-T Recommendation G.667 contains parameters and definitions for devices providing adaptive chromatic dispersion compensation. These devices are needed for transmission and detection of optical signals in a system exhibiting high levels of dyn
8、amic variation of chromatic dispersion which would otherwise impair system operation. Single and multichannel line adaptive dispersion compensators are described, as well as single and multichannel adaptive dispersion compensating transmitters and receivers which may comprise electrical or optical f
9、orms of chromatic dispersion compensation. Information on single channel and multichannel adaptive chromatic dispersion compensation implementation, as well as principles of adaptive dispersion compensation, can be found in informative appendices. Source ITU-T Recommendation G.667 was approved on 14
10、 December 2006 by ITU-T Study Group 15 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. G.667 (12/2006) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardizati
11、on Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meet
12、s every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts p
13、urview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is v
14、oluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and
15、 the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may invo
16、lve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Reco
17、mmendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database a
18、t http:/www.itu.int/ITU-T/ipr/. ITU 2007 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. G.667 (12/2006) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Terms and definitions . 2 3.1 Terms defined else
19、where 2 3.2 Terms defined in this Recommendation. 2 4 Abbreviations 5 5 Reference configurations 6 5.1 Line ADCs 6 5.2 ADC transmitters 7 5.3 ADC receivers 7 6 Parameters of ADCs . 8 Appendix I Single-channel and multichannel ADC implementation . 13 I.1 Single or multichannel line ADC implementation
20、 . 13 I.2 Single-channel ADC transmitter implementation 14 I.3 Multichannel ADC transmitter implementation. 15 I.4 Single-channel ADC receiver implementation. 16 I.5 Multichannel ADC receiver implementation . 18 Appendix II Principles of adaptive dispersion compensation (ADC). 20 II.1 Introduction 2
21、0 II.2 Adaptive dispersion compensation applications 20 II.3 Principles of adaptive dispersion compensation. 21 II.4 Chromatic dispersion monitoring. 25 Bibliography. 29 ITU-T Rec. G.667 (12/2006) 1 ITU-T Recommendation G.667 Characteristics of adaptive chromatic dispersion compensators 1 Scope This
22、 Recommendation contains parameters and definitions for devices providing adaptive chromatic dispersion compensation needed for transmission and detection of optical signals in a system exhibiting dynamic variation of chromatic dispersion. The adaptive dispersion compensating devices described inclu
23、de both single and multichannel applications. This Recommendation defines requirements and key parameters for adaptive dispersion compensators (ADC). This Recommendation distinguishes line adaptive dispersion compensators from adaptive dispersion compensating transmitters and receivers which may com
24、prise electrical as well as optical forms of chromatic dispersion compensation. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indic
25、ated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Re
26、commendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.650.2 ITU-T Recommendation G.650.2 (2005), Definitions and test methods for statistical and non-linear related attributes
27、of single-mode fibre and cable. ITU-T G.652 ITU-T Recommendation G.652 (2005), Characteristics of a single-mode optical fibre and cable. ITU-T G.653 ITU-T Recommendation G.653 (2006), Characteristics of a dispersion-shifted single-mode optical fibre and cable. ITU-T G.654 ITU-T Recommendation G.654
28、(2006), Characteristics of a cut-off shifted single-mode optical fibre and cable. ITU-T G.655 ITU-T Recommendation G.655 (2006), Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable. ITU-T G.656 ITU-T Recommendation G.656 (2006), Characteristics of a fibre and cable w
29、ith non-zero dispersion for wideband transport. ITU-T G.661 ITU-T Recommendation G.661 (2006), Definition and test methods for the relevant generic parameters of optical amplifier devices and subsystems. ITU-T G.662 ITU-T Recommendation G.662 (2005), Generic characteristics of optical amplifier devi
30、ces and subsystems. ITU-T G.665 ITU-T Recommendation G.665 (2005), Generic characteristics of Raman amplifiers and Raman amplified subsystems. ITU-T G.666 ITU-T Recommendation G.666 (2005), Characteristics of PMD compensators and PMD compensating receivers. ITU-T G.671 ITU-T Recommendation G.671 (20
31、05), Transmission characteristics of optical components and subsystems. 2 ITU-T Rec. G.667 (12/2006) ITU-T G.694.1 ITU-T Recommendation G.694.1 (2002), Spectral grids for WDM applications: DWDM frequency grid. 3 Terms and definitions 3.1 Terms defined elsewhere This Recommendation uses the following
32、 terms defined in ITU-T G.671: channel frequency range; channel insertion loss; channel insertion loss deviation; phase ripple; insertion loss; polarization dependent loss; polarization dependent reflectance; polarization mode dispersion. This Recommendation uses the following term defined in ITU-T
33、Rec. G.692: maximum central frequency deviation. This Recommendation uses the following term defined in ITU-T Rec. G.698.1: maximum spectral excursion. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 ADC transmitter: An optical transmitter containing a
34、daptive chromatic dispersion compensation functionality. 3.2.2 ADC receiver: An optical receiver containing adaptive chromatic dispersion compensation functionality. 3.2.3 dispersion compensation parameter: This parameter depends on the type of dispersion compensation device, and describes the achie
35、vable dispersion compensation performance of an ADC. For an ADC transmitter, the transmission performance related to dispersion of the ADC transmitter can be changed adaptively according to the dispersion change of the optical transmission link in which it is operating. The dispersion compensation p
36、arameter is the dispersion accommodation value of the optical transmitter signal that can be achieved by the ADC transmitter over the channel frequency range. For a line ADC, the dispersion compensation value between the input port and the output port of the line ADC can be changed adaptively accord
37、ing to the dispersion change of the optical transmission link in which the line ADC is operating. The dispersion compensation parameter is the dispersion compensation value between the input port and the output port that can be achieved by the line ADC device over the channel frequency range. For an
38、 ADC receiver, the dispersion tolerance of the receiver can be changed adaptively according to the residual dispersion value of the optical transmission link. The dispersion compensation parameter is the acceptable residual dispersion value of the optical input signal to the ADC receiver over the ch
39、annel frequency range while the BER remains lower than the specified limit. ITU-T Rec. G.667 (12/2006) 3 3.2.4 dispersion compensation tuning range: The difference between the maximum value of the dispersion compensation parameter and the minimum value of the dispersion compensation parameter of an
40、ADC device (measured as ps/nm). 3.2.5 dispersion compensation tuning time: For an ADC transmitter or a line ADC, this is the time duration from the start of a change of the dispersion compensation parameter to the time after which it remains within the limits of the new target value plus and minus t
41、he specified tolerance. This is illustrated in Figure 3-1. Dispersion compensation parameter TimeDispersion compensationtuning time Target value Target value + tolerance Target value - tolerance Figure 3-1 Illustration of dispersion compensation tuning time for an ADC transmitter or a line ADC For a
42、n ADC transmitter, the specified tolerance is the specified error of the dispersion accommodation value. For a line ADC, the tolerance is the specified error of the dispersion compensation value. For an ADC receiver, the dispersion compensation tuning time is the time duration from a step change of
43、the input signal residual dispersion to the time after which the BER remains lower than the specified limit. This is illustrated in Figure 3-2. 4 ITU-T Rec. G.667 (12/2006) Bit Error Ratio (BER) Time Dispersion compensation tuning time BER limit Error free Figure 3-2 Illustration of dispersion compe
44、nsation tuning time for an ADC receiver NOTE The tuning time will depend on the range between the current state and the new target state. 3.2.6 maximum rate of change of dispersion compensation parameter: This is the maximum rate of change of link chromatic dispersion with time that can be adequatel
45、y compensated for by the ADC device. This parameter depends on the type of the dispersion compensation device. For an ADC transmitter or a line ADC, this is the maximum value of the rate of change of link chromatic dispersion with time (in ps/nm/s) that can be compensated for while maintaining the r
46、esidual dispersion of the link within the specified tolerance. For an ADC receiver, this is the maximum value of the rate of change of link chromatic dispersion with time (in ps/nm/s) that can be tolerated while meeting the specified BER. 3.2.7 minimum optical signal-to-noise ratio: The value of opt
47、ical signal-to-noise ratio (OSNR) at point MPI-R to achieve the specified BER for the optimum link residual dispersion. This parameter depends on the type of optical system. For a single-channel system, this is the minimum value of the ratio of the signal power to the noise power density (referred t
48、o 0.1 nm) at the signal wavelength. For a multichannel system, this is the minimum value of the ratio of the signal power in the wanted channel to the highest noise power density (referred to 0.1 nm) in the range of the central frequency plus and minus the central frequency deviation or the maximum
49、spectral excursion. 3.2.8 OSNR penalty due to chromatic dispersion: The difference in the optical signal-to-noise ratio at point MPI-R to achieve the specified BER between optimum link residual dispersion and the worst value for all specified values of link residual dispersion. 3.2.9 ADC receiver sensitivity: The value of mean received power at point MPI-R to achieve the specified BER. This must be met for the optimum link residual dispersion with a worst-case transmitter, but does not have to be met with d
