1、ITU-T RECMN*R.LOS 93 E 48b2591 0593234 508 E I NTE R NATIONAL TELECOM M U N I CATION U N ION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF TU TELEGRAPHY TELEGRAPH TRANSMISSION R.105 (03/93) DUPLEX MULDEX CONCENTRATOR, CONNECTING A GROUP OF GENTEX AND TELEX SUBSCRIBERS TO A TELEGRAPH EXCHANGE BY
2、ASSIGNING VIRTUAL CHANNELS TO TIME SLOTS OF A BIT-INTERLEAVED TDM SYSTEM ITU-T Recommendation R.105 (Previously “CCITT Recommendation”) FOREWORD The IT Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for s
3、tudying technical, operating and tariff 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 IT-T Study
4、Groups which, in their turn, produce Recommendations on these topics. ITU-T Recommendation R.105 was revised by the ITU-T Study Group IX (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 Unio
5、n (ITU), the CCITT ceased to exist 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 Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector.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 public
6、ation of this Recommendation, no 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 str
7、ucture. 2 telecommunication administration 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, elec
8、tronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. ITU-T RECMN*R.LO5 93 W 4862593 0593236 380 W CONTENTS Page 1 Channel types . 1 2 System capacity 1 3 Multiplexing system specifications 2 4 Virtual channel parameters . 2 5 Link performance and av
9、ailability indicators . 3 Recommendation R.105 (03/93) 1 ITU-T RECtlN*R.LOS 93 I 4862593 0593237 2L7 I Recommendation R.105 DUPLEX MULDEX CONCENTRATOR, CONNECTING A GROUP OF GENTEX AND TELEX SUBSCRIBERS TO A TELEGRAPH EXCHANGE BY ASSIGNING VIRTUAL CHANNELS TO TIME SLOTS OF A BIT-INTERLEAVED TDM SYST
10、EM (Malaga-Torremolinos, 1984; amended at Melbourne, 1988 and at Helsinki, 1993) The CCITT, considering (a) dation R.lO1; that the specifications of code and speed dependent TDM muldexes are already given in Recommen- (b) telex subscribers to an exchange; that code and speed dependent TDM muldexes c
11、an be successfully used for connecting a group of gentex and (cl i.e. allocating time slots to subscribers only while they are operating; that a considerable increase in the efficiency of muldex channel utilization may be achieved by concentration, (4 that the busy-hour load generated by gentex and
12、telex subscribers averages from 0.05 to 0.2 erlang; (e) the TDM method, that both the virtual and assigned (fixed) telegraph channels can be set up on the same aggregate channel using unanimously declares the view that, when a bit-interleaved TDM system is used on gentex and telex subscriber lines f
13、or concentrating telegraph signals by assigning virtual channels to time slots in the 2400 bids aggregate bit stream, the equipment should meet the following requirements: 1 Channel types 1.1 2400 bids aggregate bit stream for the duration of their seizure. The duplex muldexkoncentrator should ensur
14、e that virtual channels are only allocated time slots in the 1.2 specific time slots in the 2400 bids aggregate bit stream. The duplex muldexkoncentrator should also ensure that assigned (fixed) channels are permanently allocated 1.3 Virtual channels should ensure the connection of gentex and telex
15、subscribers operating at 50 bauds and using the International Telegraph Alphabet No. 2 (ITA2) code who have an average load of 0.05 to 0.2 erlang. The use of other rates requires further study. 1.4 Recommendation R.lO1, alternative B. Assigned (fixed) channels should ensure data and telegraph signal
16、 transmission in compliance with 2 System capacity 2.1 combination within the range of the 2400 bids aggregate rate. The duplex muldexkoncentrator should ensure the setting-up of virtual and assigned channels in any 2.2 When a system has only virtual channels, the number of connected subscribers wit
17、h an average load of 0.05 to 0.1 erlang each should not exceed 256 and with an average load of 0.1 to 0.2 erlang each should not exceed 128. In either case, the percentage value of the failures to connect is not more than 0.1%. Recommendation R.105 (03/93) 1 ITU-T RECMN*R.L05 93 M L1862591 0593238 1
18、53 m 2.3 channels, should comply with Recommendation R. 101, alternative B. When a system has only assigned (fixed) channels, their number, depending on the types and rates of the 3 Multiplexing system specifications Multiplexing scheme, frame structure, frame synchronization, aggregate signal param
19、eters, interfaces, telegraph signal parameters at input-output and telegraph signal delay time should conform to Recommendation R. 1 01, alternative B. 4 Virtual channel parameters 4.1 (Recommendation U. 1). Virtual channels are intended for use on the telex network subscriber section with type A an
20、d type B signalling 4.2 necessary: Seizure of virtual channels may be from either end. In order to decrease the probability of call collisions it is - to perform blocking of the backward path immediately after the first calling signal stop element polarity appearing in a receiver vacant channel posi
21、tion; - to establish the following order for seizure of time slots in the opposite muldexes; - for a muldex installed at the exchange seizure should start with the first in a frame-free channel time slot while for the opposite muldex seizure begins with the last free channel time slot. When encounte
22、ring a call collision, a through-connection should be given to a call coming from the telegraph exchange, and a busy signal should be sent to the calling subscriber. 4.3 statistical muldexkoncentrator assemblies. In the initial state, a virtual channel should be free and a start polarity should be t
23、ransmitted over it between 4.4 When a cuff arrives, i.e. stop polarity with an interval of more than 150 ms, either from the subscriber side or from the exchange side, a virtual channel should be seized. and a stop polarity having a duration of 140-160 ms should be transmitted over it to the remote
24、side followed by the transmission of two start-stop characters having a length of 8 units each in accordance with Figure 1. The signal elements indicated as i to 8 are used for the transmission of an 8-digit conventional number indicating which subscriber (maximum 2* = 256; see also 2.2 above) idsho
25、uld be connected to the equipment. 4.5 For error protection of a conventional number, transmitted over a channel, the following should be carried out: - aparitycheck; - a check for anticoincidence of a convention number with any of the numbers of a circuit already seized. In the case of an error or
26、coincidence of a conventional number a service signal (a busy pulse signal or “OCC“) should be transmitted to the connection initiator side (a customer or exchange), returning a customer or exchange to initial state. 4.6 The element “C“ of the second start-stop character (see Figure I) is used for p
27、arity check. A parity check element should correspond to the even number of elements in Z condition. Element “C“ of the first start-stop character remains vacant and may be used for service purposes. 2 Recommendation R.105 (03D3) - T Start1 2 3 4 C Stop NOTE - Unit No. 1 of the code is the least sig
28、nificant; unit No. 8 of fie code is the most significant. start5 6 7 8 C Stop FIGURE 1R.105 Structure for transmission of the conventional number in the virtuai channel CZl I I I I I I I i I I I I I I I: 4.7 When the setting up of a virtual channel fails because all time slots are engaged by other v
29、irtual or assigned (fixed) channels, a busy signal, the structure of which is specified by current CCIT Recommendations should be returned to the calling subscriber side. 5 Link performance and availability indicators A system must be provided for monitoring performance and availability in accordance with Recommendation R. 118. Recommendation R.105 (03/93) 3 ITU-T RECMN*R=LOS 93 4862573 0593240 BOL E Printed in Switzerland Geneva, 1994
