1、 ITU-T RECMNXR-LO1 93 48b259L 0593211 TOO W INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TELEGRAPHY TELEGRAPH TRANSMISSION R.1 O1 (03193) CODE AND SPEED DEPENDENT TDM SYSTEM FOR ANISOCHRONOUS TELEGRAPH AND DATA TRANSMISSION USING BIT INTERLEAVING ITU-T
2、Recommendation R.lO1 (Previously “CCITT Recommendation”) ITU-T RECNN*R.LOL 73 E 4862573 0573232 947 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 ta
3、riff questions and issuing Recommendations 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, produ
4、ce Recommendations on these topics. ITU-T Recommendation R. 101 was revised by the ITU-T Study Group IX (1 988- 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 CCITT ceased to ex
5、ist as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-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 Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector.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, n
6、o change has been made in the text to references containing the acronyms “CCITT, 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 adm
7、inistration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1994 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including
8、 photocopying and microfilm, without permission in writing from the ITU. 1 2 3 4 5 6 7 a 9 10 11 ITU-T RECMN*R.LOL 73 .I 4862571 0593233 83 m CONTENTS System capacity Start-stop channel outputs Start-stop channel inputs Multiplexing details 4.4 Alternative A 4.5 Alternative B . . Frame structure . 5
9、.5 Alternative A 5.6 Alternative B . Synchronizing 6.3 Alternative A . 6.4 Alternative B . Telex signalling . Aggregate signals and interface . System clock arrangements System maintenance, control and alarms . Link performance and availability indicators . References . Recommendation R.lO1 (03193)
10、Page 1 2 3 4 4 4 4 4 6 10 10 11 11 13 14 14 14 14 i ITU-T RECMN*R-LOL 93 111 4862593 0573234 73T W Recommendation R.lO1 CODE AND SPEED DEPENDENT TDM SYSTEM FOR ANISOCHRONOUS TELEGRAPH AND DATA TRANSMISSION USING BIT INTERLEAVING (Geneva, 1976; amended at Geneva, 1980, Malaga-Torremolinos, 1984; Melb
11、ourne, 1988 and at Helsinki, 1993) The CCITT. considering (a) telephone-type circuit may be achieved by using time-division multiplexing (TDM) techniques; that the economic transmission of large numbers of anisochronous telegraph and data services over a single (b) hierarchy as well as on an analogu
12、e telephone-type circuit in association with standard data modems; that the multiplexing system should be capable of operating as a sub-multiplexer within a higher order TDM (c the application of simple code-dependent multiplexing techniques: that the codes and speeds used for anisochronous telegrap
13、h and data transmission are well defined, permitting (4 that code-dependent multiplexing provides inherent regeneration of start-stop signals carried by the system; (e) that, while it is foreseen that the main application would be for telex traffic, the multiplexing system should be capable of simul
14、taneously transmitting the complete range of standard anisochronous speeds and codes likely to be required by users; (f) that the multiplexing system should be capable of accepting for transmission all types of telex signals and of regenerating those signals at the channel outputs within the toleran
15、ces specified in the relevant CCITT Recommendations; (g) speeds, codes and signalling types in the same transmission system; that the multiplexing system should permit the efficient mixing of various combinations of anisochronous (h) transmission of interleaved elements, that the minimum duration of
16、 signal transfer delay through the TDM system could be achieved by the unanimously declares the view that, where bit-interleaved code and speed dependent TDM systems are used for anisochronous telegraph and data transmission with an aggregate bit rate of 2400 bit/s carried either by an analogue tele
17、phone-type circuit or by a higher order TDM, the equipment shall be constructed to comply with the following standard: 1 System capacity 1.1 The capacity of the system shall be 46 channels at 50 bauds (7.5 units including a stop element of 1.5 units). 1.2 For other modulation rates two alternatives
18、are allowed. 1.2.1 Alternative A 1.2.1.1 Channels at 75 bauds (7.5 units including a stop element of 1.5 units) shall be accommodated. See 5.5.2 below. 1.2.1.2 Further study is needed to accommodate other modulation rates. Recommendation R.lO1 (03/93) 1 ITU-T RECMN*R.LOL 93 W 48b2591 0593215 656 1.2
19、.2 Alternative B 1.2.2.1 indicated for homogeneous configurations. The modulation rates and character structures shown in Table 1 shall be accommodated with the capacities 1.2.2.2 The TDM system shall be capable of multiplexing the eight modulation rates shown in Table i simultaneously. TABLE 1R101
20、System capacity (alternative B) Modulation rate (bauds) 50 75 100 110 134.5 150 200 300 Character structure Character length (units) 7.5 7.5 7.5 or lo ;:r 11 9 10 Stop element (units) 1.5 1.5 1 1.5 1 2 1 1 1 2 1 1 1 2 Number of channels (homogeneous configuration) 46 30 22 22 15 15 IO 7 2 Start-stop
21、 channel inputs 2.1 signals with a stop element of 1.4 units shall be at least k 1.4%. The modulation rate tolerance that shall be accepted on continuous incoming 50- and 75-baud start-stop 2.2 When receiving characters at 50 or 75 bauds having nominally 1.5-unit stop elements, the system shall be c
22、apable of transmitting without error, isolated incoming characters that have a one-unit stop element, occurring at a maximum rate of one per second. 2.3 The minimum interval between start elements of undistorted successive continuous characters that may be presented at the channel input when the nom
23、inal modulation rate is 50 or 75 bauds shall be 145 5/6 or 97 U9 ms respectively. 2.4 There shall be no restriction on the continuous transmission of all characters specified in clause 1 above (e.g. combination No. 32 of International Telegraph Alphabet No. 2) when they are presented at the maximum
24、permitted rate. 2.5 a nominal character length and rate shall be at least 40%. The effective net margin on all channel inputs when undistorted signals are received from a transmitter having 2.6 duration and shall be accepted if equal to or more than 0.6 units duration. At the nominal signalling rate
25、, an input character start element shall be rejected if equal to or less than 0.4 units 2 Recommendation R.101 (03/93) 2.7 stream in the case of Elements corresponding to start polarity (at the distant multiplexer output) shall be inserted in the aggregate a) unequipped channels; b) equipped but una
26、llocated channels; c) open-circuit line condition at the local start-stop channel input. 2.8 The maximum tolerance on modulation rates other than 50 and 75 bauds shall be i 3%. 3 Start-stop channel outputs 3.1 The maximum degree of gross start-stop distortion shall be 3% for all permitted modulation
27、 rates. 3.2 nominal modulation rate shall be 0.2%. The maximum difference possible between the mean modulation rate of the channel output signals and the 3.3 range of this Recommendation, the minimum stop element duration released at the output shall be 1.25 units. 3.4 When characters having a nomin
28、al 1- or 2-unit stop element are presented at any input rate within the specified range of this Recommendation, the minimum stop element duration released at the output shall be 0.8 or 1.8 units respectively. When characters having a nominal 1.5-unit stop element are presented at any input rate with
29、in the specified 3.5 failure conditions: Channel output shall be controlled as specified below in the event of recognition of any of the following a) carrier loss signalled by the modem (OFF condition of received line signal detector - circuit CT109, Recommendation V.24 1 I); loss of aggregate signa
30、l (defined as a period of 280 ms without a transition on the aggregate); b) c) loss of synchronization. 3.6 of the affected TDM: Within 4 ms of the recognition of the failures described in 3.5, the following shall occur to the channel outputs 3.6.1 Leased channels - Two options shall be possible on
31、a per channel basis: a) b) set to steady start polarity; set to steady stop polarity. 3.6.2 Circuit-switched service - Two options shall be possible on a per channel basis: a) b) steady start polarity at the channel output; loopback of the channel towards the local end for a period of 5 f 1 seconds,
32、 after which channel outputs shall revert to steady start polarity. Additionally for alternative B, the traffic path shall be maintained towards the distant multiplexer terminai during this loopback interval. NOTE - The actions taken in case 3.6.2 a) shall ensure that, after recognition of failure,
33、no 50-baud channel used for circuit-switched service shall produce an output pulse of stop polarity of longer than 20 ms or a series of 20-111s pulses of stop polarity. It should be noted that 20-ms pulses can cause difficulty with some switching equipment. The loopback option in 3.6.2 b) is provide
34、d in order to avoid clearance of established connections during short breaks and thus avoid excessive recall attempts. 3.7 The affected terminal shall signal its synchronization status to the distant terminal in accordance with 6.3.5 for alternative A and 6.4.2 for alternative B. The distant termina
35、l shall control its channel outputs in accordance with 3.6 above with a delay that shall not exceed 600 ms (measured from the instant of failure), ignoring the propagation time of the bearer circuit. Alternatively, for alternative B, leased channels have the option, at the customers request, of main
36、taining the traffic path in the unaffected direction. NOTE - When leased circuits, particularly simples ones are set up on the TDM systems by using V.26 or V.27 modem, it is preferable to use the altemative B in this Recommendation. Recommendation R.lO1 (03/93) 3 ITU-T RECMN*R.LOL 93 M 4862593 05932
37、37 429 M 4 Multiplexing details 4.1 Channel interleaving shall be on a bit basis. 4.2 Both start and stop elements of each input character shall be transmitted through the aggregate. 4.3 The transfer delay for 50- and 75-baud signals through a pair of terminals connected back-to-back (excluding the
38、modems) shall not exceed 2.5 units. This delay shall be measured from the reception of the start element of a character at an input channel of one terminal until the corresponding start element is delivered from the output channel of the second terminal. 4.4 Alternative A 4.4.1 Multiplexing details
39、for higher modulation rates remain for study. 4.5 Alternative B 4.5.1 exceed 3.5 units. The maximum transfer delay for all other permitted channel speeds for back-to-back terminals shall not 4.5.2 aggregate signal. 1 10-baud characters are conveyed on a lO-bit/s bearer channel by transmitting at lea
40、st one stop element in the 4.5.3 stop polarity before the character start elements in the aggregate signal. 134.5-baud characters are conveyed on a 150-bith bearer channel by transmitting the necessary filling bits of 5 Frame structure 5.1 A unique subframe of 47 bits shall be used. 5.2 A 47-bit sub
41、frame shall consist of one synchronization bit in the first bit position and 46 traffic bits. 5.3 A fundamental frame consisting of two consecutive subframes shall be used. 5.4 Two alternative framing arrangements are allowed; however, the channel numbers used throughout this Recommendation represen
42、t the last two digits of a 4-digit numbering scheme - and are shown in Recommen- dation R. 1 14. This channel numbering scheme (see Tables 3,4 and 5) covers both framing arrangements. 5.5 Alternative A 5.5.1 Two scrambling techniques are used: 5.5.1.1 pattern used. Channels not equipped are transmit
43、ted as A (start) polarity. Alternate frame slots have inverted signal polarity. The chart of frame structure (see Table 2) indicates the 5.5.1.2 The channels are arranged for external interconnection with assignment of a sequence of channel numbers (channel 1 through channel 46). These channel numbe
44、rs are distinct from frame slot assignment. (This is comparable to a VFTs having both a frequency assignment and a channel number.) The channel numbering sequence is scrambled with respect to the frame slot sequence. This technique is useful not only for ensuring a good distribution of transitions,
45、but also for simplifying mixed speed programming. 5.5.2 In Table 2, higher speed channels may be substituted for multiple low-speed channels. The resulting channel should bear the number of the lowest channel replaced. For example, when channels 02 and O4 are replaced by a75-baud channel, the 75-bau
46、d channel should be known as channel 02. (See Table 3 for the relative numbering of 5 and 75-baud channels.) 4 Recommendation R.lO1 (03/93) ITU-T RECMN*R-LOL 93 4862593 0593238 365 Subframe slot Aggregate Channel polarity number corresponding to Channel speed Z polarity on low-speed channel Subframe
47、 slot Channel number 18 19 33 A 50 34 Z 50 43 39 A TABLE 2hU101 Frame for forty-six SO-band channels with provision for 75-baud channels (Alternative A) I Aggregate polarity corresponding to Z polarity on low-speed channel :hanne1 speed 1 SYNC 1 50 Not applicable 50a) 50 50 50 28 I 08 I Z 29 I 11 A
48、50 50 I61O91 A 1501 30 I 12 I Z 171101 1501 50 50 A 50 9 13 Z 50 10 17 A 50 11 18 Z 50 12 21 A 50 Z 50 50 35 I 23 1 A 36 24 Z 37 27 A 50 50 13 22 Z 50 14 25 A 50 38 28 Z 39 32 A 50 50 I l5 I 26 I z 1-71 50 50 50 42 I 36 I Z 50 50 44 I 40 Z 50 50 50 41 46 A a) Any horizontal pair, such as channels 02
49、 and O4 (.e. subframe slots 2 and 25), may be replaced by a 75-baud channel. (Slots 1,24 and 47 excepted.) In this case “fill” pulses of A polarity must be inserted in each character following element numbers 2 and 5 (see Recommendations cited in 121 for element numbers with International Telegraph Alphabet No. 2). Recommendation R.lO1 (03/93) 5 9 4862593 0595540 339 TABLE 3AX.101 Channel allocation scheme for Alternative A 75-baud 50-baud 1 channels I 1 22 13 24 36 23 35 TG90 1 61 O-94dO 1 - - 5.6 Alternative B 5.6.1 The channel allocation in the fundamental frame is s
