1、 STD-ITU-T RECMN G.777-ENGL L77b qBb2591 0b23q57 q27 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU GENERAL ASPECTS OF DIGITAL TRANSMISSION SYSTEMS G.797 (03/96) CHARACTERISTICS OF A FLEXIBLE MULTIPLEXER IN A PLESIOCHRONOUS DIGITAL HIERARCHY ENVIRONMENT I
2、TU-T Recommendation G.797 (Previously “CCITT Recommendation”) FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommen- d
3、ations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
4、The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). ITU-T Recommendation G.797 was prepared by -T Study Group 15 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 19th of
5、March 1996. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1996 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any mean
6、s, electronic or mechanical, including photocopying and microfilm, without permission in writing from the IT. - STD-ITU-T RECMN G.777-ENGL L97b iBb2571 Ob23457 2TL B CONTENTS Scope of the Recommendation 1 2 3 4 5 6 7 8 9 10 11 12 General characteristics . 1.1 Definitions 1.2 Abbreviations 1.3 1.4 Si
7、ze . 1.5 Modularity 1.6 Timing signal Functions Application of the equipment . 2.1 Mapping 2.2 Signal processing 2.3 Concentration function for switched services . 2.4 Management . Functional representation of the equipment and definition of reference points . 3.1 Functional representation 3.2 Defin
8、ition of functional blocks . 3.3 Definition of Reference Points . Tributary interfaces 4.1 Analogue interfaces 4.2 Digital interfaces . Aggregate interfaces . 5.1 2048 kbit/s interface . 5.2 8448 kbit/s interface . 5.3 34 368 kbit/s interface 5.4 139 264 kbii/s interface Synchronization interface at
9、 2048 kHz Local control interface . Power interfaces . Defect or failure conditions and consequent actions for the tributary interfaces . 9.1 Defect or failure conditions 9.2 Consequent actions . Defect or failure conditions and consequent actions for the aggregate 10.1 Defect or failure conditions
10、10.2 Consequent actions for defect or failure conditions related to the A Reference Point . 10.3 Consequent actions for defect or failure conditions related to the B2 Reference Point . 10.4 Consequent actions for defect or failure conditions related to the E2E2 Reference Point . Defect or failure co
11、nditions and consequent actions for the core of the equipment 1 1.1 Defect or failure conditions 1 1.2 Consequent actions at the 02 or Al or ElEl or L2 or N2 Reference Points . Performance monitoring . Recommendation 6.797 (03/96) Page 1 1 1 1 2 3 3 5 5 5 5 5 5 5 5 7 8 8 8 13 20 20 21 22 22 22 22 22
12、 22 22 24 26 26 28 29 29 29 29 31 33 1 13 Performance of the equipment . 13.1 Jitter 13.2 Transfer delay . 13.3 Slips 13.4 Service availability . 13.5 Error performance . 13.6 Bit sequence independence . 14 Management . Appendix1 . I . 1 1.2 1.3 1.4 1.5 1.6 1.7 Baseband line transmission system . Ph
13、ysical model of the line transmission system Functional description of the DCE . Functions of Tu functional block . Requirements for a line transmission system using 2B iQ line code DCE Management channel . General Management System Unit . Page 33 33 35 35 35 36 36 36 36 36 36 37 31 39 43 43 11 Reco
14、mmendation G.797 (03/96) SUMMARY This Recommendation covers functional requirements for a Flexible Multiplexer (FM). The FM stands for an equipment or the relevant functions able to provide time division multiplexing and demultiplexing of signais supporting a variety of user services. In addition th
15、e flexible multiplexer provides enhanced management capabilities. It is based on 64 and n x 64 kbids services. The flexible multiplexer can be used in the access part of a digital transmission network (PDH in the case of this Recommendation). This Recommendation mainly describes the provision of ana
16、logue and digital leased line services. Some technical solutions for the transport of PSTN and ISDN signais are also indicated. The provision of on-demand services according to Recommendations G.964 and G.965 speciQing the V5 interfaces are for further study. Recommendation G.797 (03/96) . 111 STD-I
17、TU-T RECMN G.777-ENGL L99b = 48b259L Ob234b3 722 Recommendation G.797 CHARACTERISTICS OF A FLEXIBLE MULTIPLEXER IN A PLESIOCHRONOUS DIGITAL HIERARCHY ENVIRONMENT (revised 1996) Scope of the Recommendation This Recommendation gives the characteristics of a flexible multiplex equipment able to handle
18、a variety of services with transparency for service provider, allowing enhanced management capabilities and to be used in the local network. Concentration function for switched services is not precluded and further study is necessary to cover this application. Tributaries of this multiplexer present
19、 usual interfaces related to services to which they are connected. Internal mapping functions are based on Recommendation G.704 and on 64 and n x 64 kbit/s signals. The handling of sub-64 kbit/s signals is not precluded. The equipment is intended to be installed in a Plesiochronous Digital Hierarchy
20、 (PDH) environment. Management of the equipment is in line with general principles of the Telecommunications Management Network (TMN). 1 General characteristics 1.1 Definitions For the purposes of this Recommendation, the following definitions apply. Refer also to 1.2 for additional functional descr
21、iption. 1.1.1 flexible access system (FA): A flexible access system is a means of providing a wide range of telecom- munication services to customers in a flexible manner. These services may be delivered at the customer premises or from a public network location. On the network side, connections are
22、 established to the appropriate service networks. The flexible access system is managed by the TMN. 1.1.2 supporting a variety of user services. In addition, the device provides enhanced management capabilities. The flexible multiplexer is part of flexible access system. flexible multiplexer (FM): A
23、 device that provides time division multiplexing and demultiplexing of signals 1.1.3 used in conjunction with the flexible multiplexer to constitute a flexible access system. 1.1.4 monoservice 2048 kbis G.704 frame: A digital signal with structure according to 2.3/G.704 and clause YG.704 comprising
24、constituent 64 kbit/s or n x 64 kbit/s signals and any related signalling corresponding to only one particular service network. 1.1.5 constituent 64 kbit/s or n x 64 kbit/s signals and any related signalling corresponding to various service networks. 1.1.6 embedded operation channel (EOC): An embedd
25、ed operation channel is a physical channel of the managed network used for management communication purposes, specifically to exchange information between Network Element (NE) functions and Operations System (OS) or Mediation Device (MD) functions. It may be carried over different physical bearers.
26、flexible access termination (FAT): In a plesiochronous digital hierarchy, the flexible access termination is multiservice 2048 kbits G.704 frame: A digital signal with stnicture according to 2.3/G.704 comprising 1.2 Abbreviations This subclause contains the abbreviations which are not defined in the
27、 core text of the Recommendation. ADPCM AIS Alarm Indication Signal Adaptive Differential Pulse Code Modulation Recommendation G.797 (03/96) 1 CRC DC DCE DTE ES FAS fro IS0 MTBF MTTR WAS PCM PPm Q SB-ADPCM SES TS TSO TS16 u1 Cyclic Redundancy Check Direct Current Data Circuit-terminating Equipment D
28、ata Terminal Equipment Errored Second Frame Alignment Signal Frame O of the CAS G.704 multiframe International Standardization Organization Mean Time Between Failure Mean Time To Repair Non Frame Alignment Signai Pulse Code Modulation part per million The NE interface to the TMN Sub-Band Adaptive Di
29、fferential Puise Code Modulation Severely Errored Second Time Slot Time Slot O of a 2048 kbis G.704 frame Time Slot 16 of a 2048 kbis G.704 frame Unit Interval 1.3 Application of the equipment 1.3.1 Network configurations The recommended network configurations are given in Figures 1 and 2. Figure 3
30、describes the distribution of functions in Flexible Access system. Tributary Optional duplic a) b) one of a number of 2048 kbit/s signal(s); c) an internal oscillator with an accuracy of frequency of a range of f 1 ppm to f50 ppm depending on application. NOTES 1 2 synchronous network. 3 In case b),
31、 a 2048 kbit/s signal could be a tributary signal. The internal oscillator should not be used as a primary timing source when the flexible multiplexer is connected to the The provision of the timing signal to an output of synchronization interface for the purpose of synchronizing another equipment o
32、r to control the internal timing signal is an optional function. On failure condition on the active synchronization signal, it shall be possible to programme a fall-back strategy up to three steps, see 11.1.3. Complementary information is given in clause 14 corresponding to the management aspects of
33、 the equipment. 2 Functions 2.1 Mapping The mapping function relates to the allocation of time slot(s) in any 2048 kbit/s G.704 framed aggregate signal to any tributary signal. The mapping function is based on Recommendation G.704. 2.2 Signal processing The signai processing covers functions such as
34、 analogue to digital conversion, rate adaptation, handling of signalling information and control signals. 2.3 Concentration function for switched services When implemented, this function should apply the principles provided in Recommendation G.965. The corresponding requirements are not described in
35、 this Recommendation and remain for further study. 2.4 Management The management includes control functions and provision of maintenance information. The management functions of the flexible multiplexer are presented in clause 14. 3 Functional representation of the equipment and definition of refere
36、nce points 3.1 Functional representation Figure 4 describes the functional representation of the flexible multiplexer and locates appropriate Reference Points. Recommendation 6.797 (03/96) 5 STD*ITU-T RECMN G.777-ENGL L77b LiBb257L Ob23qbB 2Oi M Sd R x L -J c t I n e c d O Y u1 w E .-.-.-.- In (B -
37、I v) .- O k (3 I c I ! O -I r I I I E 6 Recommendation G.797 (03196) 3.2 Definition of functional blocks 3.2.1 Plesiochronous Physical Interface (PPI): The plesiochronous physical interface concerns the aggregate interface, terminating the related transmission system. When appropriate, it also extra
38、cts clock signal from the received signal. 3.2.2 Tributary Physical Interface (TPI): The tributary physical interface concerns a variety of service related interfaces terminating the corresponding circuits. When appropriate, it also extracts clock signal from the received signals and operates on any
39、 controllsignalling signals. 3.2.3 Plesiochronous Higher Order Path Termination (PHFT): The plesiochronous higher order path termina- tion terminates high order logical signals of aggregate interface at 8448, 34368, 139264 kbit/s. Related functions concern frame generation and recovery and detection
40、 of defect or failure condition on higher order logical signal. 3.2.4 dations G.742, G.75 1. Plesiochronous Higher Order Multiplexer (MX): Digital multiplexing function according to Recommen- 3.2.5 Plesiochronous Lower Order Path Termination (PLPT): The plesiochronous lower order path termination te
41、rminates 2048 kbits logical signals at the aggregate side of the equipment. Related functions concern frame generation and recovery and detection of defect or failure condition on 2048 kbit/s logical signal. 3.2.6 from tributary side to related 2048 kbits G.704 logical frame signal. Cross Connect Fu
42、nction (XC): The cross connect function allows the mapping of 64 or n x 64 kbits signals 3.2.7 necessary to be able to handle it in a G.704 type frame format. Tributary Signal Adaptation (TSA): The tributary signal adaptation modifies tributary signal when 3.2.8 Tributary Path Terminationributary Si
43、gnal Termination (TPTmST): This function is similar to PLPT function when the tributary interface is related to an application of 2048 kbits G.704 frame. For other interfaces, it generates or terminates information and any signalling or control signal. 3.2.9 generates) electrically the external sync
44、hronization signal. Multiplexer Timing Physical Interface (MTFI): The multiplexer timing physical interface terminates (or 3.2.10 necessary for the flexible multiplexer. Multiplexer Timing Source (MTS): The multiplexer timing source provides all internal timing signals 3.2.11 Equipment Management Fu
45、nction (EMF): The equipment management function gives the possibility to the local user or to the TMN to perform all the management functions of the equipment. It is connected to every functional block of the flexible multiplexer. 3.2.12 Message Communication Function (MCF): This functional block is
46、 able to terminate and generate the embedded operation channel(s) (EOC) which may be transported on a Sa-bit or on several Sa-bits of TSO either on aggregate side or on tributary side of the flexible multiplexer. Alternatively, the EOC may be transported on a 64 kbits TS at the aggregate side. This
47、functional block is able to interwork with the local user via the F or P interfaces or via the m Reference Point. 3.2.13 ADPCM transcoding, conference bridging, broadcasting. Special Function (SF): The special functions could be point to multipoint mode of operation, PCM to 3.2.14 abcd bits of TS16,
48、 when used, in relation with correspondent 64 kbit/s TS. Channel Associated Signalling (CAS) Cross Connect (CAS XC): This realizes the cross connection of 3.2.15 for the digital path. The switchover function may be done under the control of CMF or automatically. Automatic Protection Switch (APS): Th
49、is optional function is used when 1 + 1 protection switch is required Recommendation 6.797 (03/96) 7 3.3 Definition of Reference Points -A -B High order logical signal. - C, D -E - E - G, H -J -K -L - M -N -0 -v - Si Management points. - TO Internal timing signal. - T1 Synchronization signal derived from a 2048 kbit/s aggregate signal. - T2 Synchronization signal derived from a 2048 kbit/s tributary signal. - T3, T4 2048 kHz external synchronization signal. - Tx 2048 kHz signal derived from a 2048 kbit/s tributary or aggregate signal not necessarily synchrono
