ITU-T G 962-1993 Access Digital Section for ISDN Primary Rate at 2048 kbit s (Study Group XVIII) 55 pp《ISDN 基础率在2048 kbit s下用存取数字单元》.pdf

1、CCITT RECMN*G-962 73 W 4862573 0580385 280 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU DIGITAL SECTIONS AND DIGITAL LINE SYSTEMS G.962 (03193) ACCESS DIGITAL SECTION FOR ISDN PRIMARY RATE AT 2048 kbits ITU-T Recommendation G.962 (Previously “CCIlT Reco

2、mmendation”) CCITT RECMN*G.962 93 m 48b259L 058038b lL7 m FOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations

3、 on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. ITU-T

4、Recommendation G.962 was prepared by the IT-T Study Group XVIII (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCIT ceased to exist as of 28 February 1993. In its place, t

5、he ITU Telecommunication Standardization Sector (XT-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change bas been made in the text to refere

6、nces containing the acronyms “CCIT, CCIR or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 telecommunication administration and a recognized operating agency

7、. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permissi

8、on in writing from the ITU. _- CCITT RECMNtG.962 93 Ei 4862591 0580387 053 = CONTENTS General 1.2 Configuration 1.3 Application . 1.4 Abbreviations Modelling and relationship between the digital section and the ET Functions . 3.1 B-channel . 3.2 HO-channel . 3.3 H1-channel . 3.4 D-channel . 3.5 Bit

9、timing . 3.6 Octet timing 3.7 Frame alignment . 3.8 CRC procedure . 3.9 M-channel 3.10 Power feeding . 3.11 Operation and maintenance . Network performance . 4.1 Availability . 4.2 Signal transfer delay . 4.3 Error performance . 4.4 Jitter . 1.1 scope Operation and maintenance . 5.1 General . 5.2 Co

10、ntrol facilities . 5.3 Monitoring Operation and maintenance procedures 6.1 Pariitioning of functions 6.2 Definitions of signals at the T reference point . 6.3 Definition of DS state machine . 6.4 Definition of ET layer 1 state machine Annex A . System management requirements A.2 System management re

11、quirements A.l Introduction Annex B . Allocation of signai codings and DS state transition tables for option 2 according to Recommen- dation 1.604 at 2 Mbit/s B.l Introduction B.2 DS state transition table B.3 Coding of signals at V3 reference point . B.4 Allocation of signai elements to functional

12、elements . B.5 Indication of CRC-4 errors detected at the T reference point to the ET Recommendation 6.962 (03193) Page 1 1 1 2 2 2 5 5 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 8 8 11 11 12 12 12 13 13 14 24 24 24 44 44 46 i CCITT RECMN*G*b2 93 ICB 4862571 0580388 TT Annex C . Allocation of signai codings

13、and DS state transition tables for option 3 according to Recommen- dation 1.604 at 2 Mbit/s C.l Introduction C.2 Signais at the V3 reference point . C.3 Definition of function elements (FES) at the V3 reference point C.4 C.5 Performance entena C.6 FES at the V3 reference point Access digital section

14、 (DS) state machine . 11 Recommend at ion G . 962 (03/93) Page 46 46 46 48 48 48 49 CCITT RECflN*G*962 93 81 486259L 0580389 92b W Recommendation G.962 ACCESS DIGITAL SECTION FOR ISDN PRIMARY RATE AT 2048 kbih (Helsinki, 1993) 1 General 1.1 Scope This Recommendation describes the characteristics of

15、an access digital section for the ISDN primary rate access between the user network interface (at the T reference point, defined in Recommendation 1.41 1) and the local exchange (at the V3 reference point, defined in Recommendation Q.512) supporting the primary rate interface structures defmed in Re

16、commendation 1.412 and the required additional functions. In this Recommendation and unless otherwise indicated, the term TE is used to indicate terminating layer 1 aspects of TEl, TA and NT2 functional groups. When the term TE indicates terminating layer 1 aspects of TE1, then according to Figure 2

17、A.411, the S and T reference points coincide. Tbe terminology used in this Recommendation is contained in Recommendations I. 1 12 and G.701. 1.2 Configuration Figure 1 shows the boundanes of the access digital section in relation to the digital system definition. Dgitai transmission system Primaty r

18、ate access digitai section t b TI 81424C-Q2/dOl NOTE - Digital transmission system refers to either a line system using metallic media, optical fibres or radio systems. FIGURE VG.962 Access digital section and transmission system boundaries Recommendation G.962 (03/93) 1 CCITT RECMN*G=962 73 Vb2593

19、0580390 648 The concept of the access digital section is used in order to allow a functional and procedural description and a definition of the network requirements. NOTE - From a functional point of view the information transferred via the reference points T and V3 are different and therefore the d

20、igital section is not symmetrical. The concept of a digital transmission system is used in order to describe the characteristics of an implementation, using a specific medium, in support of the access digital section. NOTE - The T and V reference points are defined in Recommendations 1.41 1 and 4.51

21、2. 1.3 Application The primary rate access digital section may be applied as given in Figure 2 for: - direct access to the local exchange; - remote access via a first order digital section or via higher order multiplex equipment forming a digital link to the local exchange. NOTE - In this Recommenda

22、tion, references to LT only concern the LT inside the access digital section. 1.4 Abbreviations A number of abbreviations are used in this Recommendation, some of them are commonly used in the ISDN reference configuration while others are created only for this Recommendation. These are given in the

23、following: DS Access digital section SIG Signals between LT and NTl 2 Modelling and relationship between the digital section and the ET The general model shown in Figure 3 depicts the whole ISDN customer access layer 1 and adjacent entities and provides the basis to describe the functions performed

24、by the access digital section and those performed by TE, ET and system management and how various functions are grouped. In particular, according to this model the maintenance functions specified in this Recommendation are not confined to functions performed by the access digital section but include

25、 functions associated with ET layer 1. This model includes primitive procedures between ET iayer 1, ET layer 2 and system management: i) 1.431 and Q.920/Q.921 interactions between ET layer 1 and ET layer 2 and system management based on PH and MPH primitives, respectively, as defined in Recommendati

26、on 1.431. These interactions are for the support of functions specified in Recommendations Q.920lQ.921; ii) interactions between ET layer 1 and system management for the support of functions associated with the access digital section, based on MPH primitives. The primitive procedures within TE compl

27、y with the specification according to Recommendation 1.431. This model does not constrain layer 1 arrangements between LT and “1, or the digital transmission system technology. 2 Recommendation 6.962 (03/93) CCITT RECMNUG-Sb2 93 W 4Bb2591 0580391 584 D 4 Primary rate access digitd section (Note 1 )

28、b - - NT2 - NT1 u- - - r I - - LT NT1 - - - I v3 4 b (Note 4) Line Line _ - term term - T181704PQ2/dM (Note 3) Access digitd section (Note 1) q- NOTES MUX Diaitai link G MUX ET 1 2 3 electrically identical to the V3 reference point as in the case of the direct access. 4 Recommendation. The access di

29、gital sections may include one or more regenerators. Multiple application of digital links and multiplexers may be possible, but see 4.4.2 “Jitter at the V3 reference point”. In the case of remote accesses, the digital access link is terminated at the ET by a V3 reference point which is functionally

30、 and The line terminations being part of the fmt order access digital section or the digital link are outside the scope of this FIGURE 2lG.962 Examples of equipment configurations in the ISDN subscriber prlmdry rate access: Recommendation 6.962 (03/93) 3 CCITT RECMN*G*962 93 4862571 0580392 II 4 Rec

31、ommendation G.962 (03/93) 3 Functions - U For each direction of transmission the following shall be provided: - 30 timeslots at 64 kbids, numbered 1 to 15 and 17 to 31, for the transport of any appropriate allocation of the following B-, HO- and H1-channels; 1 timeslot at 64 kbids, numbered 16, for

32、the transport of a D-channel; - Power feeding (Note 1) Operations and maintenance - - 1 timeslot at 64 kbit/s, numbered O, for frame alignment, and to follow the procedures for multiframe alignment, CRC, and maintenance. Figure 4 shows the functions which have to be supported by the primary rate acc

33、ess digital section. T reference point Access digital section V3 reference point I- - 1 B-, HO- or H1-channels 1 D-channel64 kbitk U U Bit timing U t-+ I- Octet timing I- Frame alignment - CRC procedurec - NOTES 1 medium used. Only the NT1 may be powered from the interface at the T reference point.

34、(See Recommendation 1.431 .) 2 implementations as described in Recommendation 1.604. This power-feed-function is optional and is dependent on the transmission The M-channel is not available at the T reference point in option 3 FTGLJRE 4/G.962 Functions supported in the access digital section 3.1 B-c

35、hannel This function provides for the bi-directional transmission of 30 independent B-channels each having a bit rate of 64 kbitls as defined in Recommendation 1.412. Recommendation G.962 (03/93) 5 CCITT RECMN*G.Sb2 93 4Ab259L 0580394 293 3.2 HO-channel This function provides for the bi-directional

36、transmission of up to 5 independent HO-channels each having a bit rate of 384 kbit/s as defined in Recommendation 1.412. 3.3 Hl-channel This function provides for the bi-directional transmission of one HI-channel having a bit rate of 1920 kbit/s as defined in Recommendation 1.412. 3.4 D-channei This

37、 function provides for the bi-directional transmission of one D-channel signal at a bit rate of 64 kbit/s as defined in Recommendation 1.412. 3.5 Bittiming This function provides bit (signal element) timing to enable the TE, the access digital section or the ET to recover information from the aggreg

38、ate bit stream. 3.6 Octet timing This function provides 8 kHz timing towards TE, the access digital section or the ET for the purpose of enabling an octet structure for voice codecs and for other timing purposes as required. 3.7 Frame alignment This function provides information to enable the TE, th

39、e access digital section or the ET to recover the timedivision multiplexed channels. 3.8 CRC procedure This function provides for the protection against false framing and for error performance monitoring of the access digital section. This includes the multiframe procedure defined in Recommendation

40、G.704. 3.9 M-channel For option 2 implementations, this function provides a bi-directional4 kbids data channel for the implementation of management features between ET and TE which is transparently transported in the Sa bit 4 of timeslot O of the non-frame alignment signai in accordance with Recomme

41、ndation G.704. For option 3 implementations, this function provides a bi-directional 4 kbit/s channel for the operational and management requirements for the access digital section. It shail be transported in the Sa4 bit of timeslot O, of the non-frame alignment signai in accordance with Recommendat

42、ion G.704. 3.10 Power feeding This optional function provides for remote feeding of the NT1 via the user network interface in accordance with Recommendation 1.43 1. 3.11 Operation and maintenance This function supports required actions and information for operating and maintaining the access digitai

43、 section controlled by the ET as defined in Recommendation 1.604. 6 Recommendation 6.962 (03193) The following categories of function bave been identified: - - - indications of defect conditions. commands regarding LT, regenerator, or NT1; information from LT, regenerator, or NTl; 4 Network performa

44、nce 4.1 Availability The definition of availability is given in Annex NG.821. The availability objective of the access digital section should be consistent with the availability requirement for the hypothetical reference digitai section as given in Recommendations G.801 and 1.350. 4.2 Signai transfe

45、r delay Signal transfer delay is specified for B- and D-channels and is defined as absolute signal delay between T and V3 reference points for each duection of transmission. The value shall be less than 2 ms when a system for metallic wires, optical fibre or radio system is used. The application of

46、a satellite system in the access digital section is also possible. However, for speech services, Recommendation G.114 may limit such an application until appropriate methods to control double satellite bops and switching of echo control devices are available. These methods are outside the scope of t

47、his Recommendation. In the case of remote application of the access digitai section (see Figure 2 with a digitai link between the access digital section and the ET) the signal transfer delay is defined for the access digital section between T and V3 reference points. The relevant Recommendations hav

48、e to be taken into account (e.g. signal transmission delay when the signal represents speech must be taken into account as one component of the end-to-end delay requirement of Recommendation G.114). 4.3 Error performance Error performance must be consistent with the requirements given in Recommendat

49、ion G.821, locai grade. 4.4 Jitter 4.4.1 The requirements are defined in 5.4D.43 1. Outputhput jitter at T reference point 4.4.2 The input jitter limits are described in Recommendation G.823. Jitter at the V3 reference point NOTE - If models described in Figure 2 are used to connect a customer to the ET, a jitter reducer is not required at V3. 5 Operation and maintenance 5.1 General This subclause describes the operation and maintenance functions for the access digitai section of the ISDN primary rate access. Further assumptions regarding the system management are given