Yngve Rapp - The history of Ericsson

More documents

Recommendations

Info

The Stored Program Controlled Group Selector ANC 11 and its Introduction in Mexico City Björn Lasson and Sune Lindblad LM Ericsson has designed a stored-program-controlled group selector ANC 11 made up of reed matrices. The switching stage, which is intended for very large multi-exchange networks, is used for outgoing, incoming or combined outgoing and incoming traffic in local exchanges. It can also be used as an independent local transit stage for two-wire speech transmission. ANC 11 has already been described in another publication* and is therefore dealt with only summarily in this article, the object of which is to illustrate how the switching stage is used in practice, particularly in the Mexico City network. UDC 621 395 74 ANC 11 has properties adapted to large multi-exchange networks Fig. 1a ANC 11 as outgoing group selector with a common route from all 1C.000-line groups to each destination Fig. 1b ANC 11 as incoming group selector distributing the incoming traffic to several 10,000-line groups ANC 11 was designed to serve metropolitan areas. Its basic properties which fit it for this purpose are the following. The switching stage has a large maximal capacity but can nevertheless be built up in small modules. The maximal capacity of an ANC 11 stage is 6,144 inlets and 6,144 outlets and can be extended in steps of 64 inlets and 64 outlets. If an even larger capacity is needed, two or more ANC 11 stages can be combined. It has a good circuit economy, as all circuits are accessible from each inlet (full availability). The internal congestion in the link system is very low since there is conditional selection throughout the switching system (six partial stages) and up to four reselections are possible. The permitted congestion can therefore be almost entirely assigned to the circuits. As the group selector is not graded, it is easy to install and extend. Regrading is never necessary. The routes can comprise up to 256 circuits each. The maximum number of routes that can be inserted is 256. In older exchanges with more than 10,000 lines, each 10,000-group usually has its own first group selector stage I- GV, with one route running from each 10,000-group to each of the destinations concerned. If l-GV is built up on the ANC 11 principle, however, several 10,000-groups can be connected to its inlet side, in which case only one common route is required from all of these 10,000-groups to each destination (fig. 1a). As incoming group selector, ANC 11 can also serve several incoming 10,000-groups, with corresponding reduction of the number of routes (fig. 1b). The reduced need for routes is illustrated more clearly in fig. 2a-c. This results in a further reduction of the need for circuits. SPC technique is used. Duplicated microprocessors are used foreach control and signalling unit, in addition to a separate operation and maintenance processor. Changes in the operational conditions are made by an operator sending a command from an electric typewriter (fig. 3). The system also has good traffic-rout ing properties owing to
£«*•, BJÖRN LASSON SUNE LINDBLAD Telephone Exchange Division Telefonakliebolaget LM Ericsson Fig. 2a Without ANC 11 one route is normally required from each 1C,C00-group in exchange A to each 1C,CC0-group in exchange B. and vice versa, i.e. in all 2 (mxn) Fig 2b If both exchanges are equipped with ANC 11 as l-GV. one route is required from exchange A to each 10,COO-group in exchange B. and vice versa. i.e. in all n + m Fig. 2c If both exchanges are equipped with ANC 11 both for l-GV and ll-GV/GIV. a single route is required in each direction, i.e. in all 1+1 Fig. 3 (right) Change of the operational conditions in ANC 11, c n insertion of alternative route B, can be done its well developed analysis capacity; it has, besides, many operation and maintenance facilities. Schematic structure The structure of ANC 11 is shown schematically in figs. 5 and 6, which contain the following blocks and units: Incoming selector GV-I consisting of up to 12 identical GV-I groups, each with 512 inlets. Each group hasan individual control unit of SPC type. Outgoing selector GV-O, consisting of up to 12 identical GV-0 groups with the same grouping and type of control unit as GV-I The duplicated central processing unit CE, common to twelve GV-I and twelve GV-0 groups, controls the traffic handling functions of ANC 11, such as digit analysis, link selection, circuit selection within a specific route, and switch operation. Operation and maintenance processor OMP performs supervision, traffic measurement, fault-tracing and issue of alarm, and constitutes a communication link with the input and output devices. 23 Input and output devices (I/O) of up to four types-electric typewriter, visual display, tape reader and tape punch. Grouping plan The basic module of the reed switch contains 24 cross-points which form a 4x6 matrix. Fig. 4 shows a grouping plan for GV-I with 512 inlets and 864 outlets The latter constitute links to GV-O, which has the same grouping as GV-I but reversed. ANC 11 in Mexico City's local network Mexico City is the capital and administrative centre of the country. With its roughly 10 million inhabitants it is one of the biggest cities in the world and is a centre for commerce and communications. The existing network The first automatic telephone exchange in Mexico City was installed in 1929 and was of AGF type. The local network has since been continuously extended and in June 1976 there were 62 automatic local exchanges with a total capacity of 880,000 subscriber lines. Of these ex-
Page 1: ERICSSON REVIEW 1 SODERTALJE-THE FI
Page 4 and 5: Transmission Technique Transmission
Page 6 and 7: Södertälje— the First AXE Excha
Page 8 and 9: Fig. 5 The switchroom. Space for 12
Page 10 and 11: 6 Fig. 9 One of the two central pro
Page 12 and 13: 8 Yngve Rapp at his doctoral disser
Page 14 and 15: Design of ERICOFON 700 Carl-Arne Br
Page 16 and 17: 12 Fig. 4 The base with keyset and
Page 18 and 19: Computerized Operation ana Maintena
Page 20 and 21: 16 Fig. 3 Principle of disturbance
Page 22 and 23: 18 Fig. 5 TV monitor showing alarm
Page 24 and 25: 20 Fig. 7 Operation and maintenance
Page 28 and 29: 24 Fig 4 Grouping plan for an incom
Page 30 and 31: 26 Fig 8 Local and tandem exchanges
Page 32 and 33: Transmission Properties of Paper-in
Page 34 and 35: 30 Fig. 4 Attenuation for paper-ins
Page 36 and 37: AXB 20-All Electronic, Stored- Prog
Page 38 and 39: 34 Fig. 4 In system AXB 20 separate
Page 40 and 41: 36 Fig. 6 The hardware in a functio
Page 42 and 43: 38 Fig. 8 Computerized functional t
Page 44 and 45: 40 Simplified maintenance of switch
Page 46 and 47: 42 Fig. 2 Schematic presentation ot
Page 48 and 49: 44 Fig. 5 Hardware structure of the
Page 50 and 51: 46 Fig. 7 Line adapter equipment fo
Page 52 and 53: 48 Fig. 9 The central processor is
Page 54 and 55: 50 Fig. 11 Block diagram of the inp
Page 57 and 58: The Ericsson Group With associated

Yngve Rapp - The history of Ericsson

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?