ONE-SIDED MULTISTAGE SWITCHING NETWORK

Abstract: A full access nonblocking one-sided multistage switching network, the first stage of which contains partial access switching blocks, comprises a reasonable number of used elements. Their terminals which can be connected to any other terminal of the block constitute the terminals of the switching network. The remaining terminals of the block are used for connections with the switching blocks of the next stage. The switching blocks (1 to 16) of the first stage are constructed of two triangular switches (1′, 1″ to 16′, 16″). The half of the terminals of the first triangular switch of the pair is connected with the half of the terminals of the second triangular switch of the pair, and these terminals constitute the terminals of the switching network. The remaining terminals of both switches in the first-stage blocks (1 to 16) are used for connections with the switches (18 to 32) of the next stage (17). Such a structure of one-sided switching network, in which one of the stages is constructed of partial access switching blocks, enables to obtain considerable savings of the number of used elements.

Description: This invention relates to digital switching systems. In particular it relates to a one-sided multistage switching network composed of triangular switches, which is especially useful for the construction of a telecommunication system and for telephone exchanges. The structures of integrated switches which mix in the same chip or in the same printed board both time and space switching are well known. One-sided matrices lead to so-­ called triangular switches. These switches can be used for constructing a switching network whose capacity is greater than the capacity of a single switch. Structures of one-­ sided switching networks composed of triangular switches have been presented in several papers. In publications such as J. Cornu and M. Meinck "ITT 1240 Digital Exchange: Advanced Component Technology", Electrical Communication, 1981, 56, pages 161 to 172, and W. Frank, M. C. Rahier, D. Sallaerts and D. C. Upp "System 12: Dual Switch Port", Electrical Communication, 1985, 59, pages 54 to 59, the structures of triangular switches are described. Such switches were used for constructing a switching network as described in a publication of J. M. Cotton, K. Giesken, A. Lawrence and D. C. Upp "ITT 1240 Digital Exchange: Digital Switching Network", Electrical Communication, 1981, 56, pages 148 to 160. In this switching network the triangular switches are grouped into four stages. Some of the terminals of each switch in one stage are connected with the terminals of the switches in the next stage, while remaining terminals of these switches are connected with the terminals of the switches in the previous stage. The terminals of the switching network are formed by some terminals of the switches in the first stage of the switching network. In the described switching network there are no connections between switches in the same stage. In another solution as described in a publication of A. Jajszczyk "On Triangular Digital Switching Networks", Proc. 1987 Int. Conf. on Communication Technology, Nanjing, P.R.China, 1987, pages 982 to 985, switches in some or in all stages are replaced with one-stage full access switching blocks. These blocks are composed of triangular switches. In the switching network constructed in such a way, some of the switches in the same stage are connected to each other. A purpose of the invention is the construction of such one-­ sided multistage switching networks, which can be constructed of fewer number of triangular switches than those switching networks which were previously known. According to the invention, the first stage of a switching network is composed of partial access switching blocks. In such a block some of the terminals can be connected to some other terminals, and these terminals constitute the terminals of the switching network, while the remaining terminals of the block are used for connections between the switching block and the switches of the next stage of the network. This solution enables to construct the one-sided multistage switching network, which is nonblocking and full access one, although one stage of this network, i.e. the first stage, is composed of partial access switching blocks. Such a structure of a switching networks makes it possible to construct a switching network which has fewer switches then networks previously known. Embodiments of the invention will now be described with reference to the accompanying drawings wherein: Fig. 1 shows a-partial access switching block composed of m triangular-switches, Fig. 2 shows a two-stage switching network having 128 PCM links. The switching network of Fig. 1 constitutes a partial access one-stage switching block which is composed of m triangular switches. Each of these m switches has n terminals. The first 1 terminals of the first switch are connected with 1 terminals of each of the remaining m-1 switches of the switching block, and these terminals constitute the terminals of the switching network through which the connection with any other terminal can be made. The remaining m(n-1) terminals of the block can be used for connections with switches in the next stage from the terminals 1 to n-1 of the first triangular switch to the terminals (m-1)(n-1)+1 to m(n-1) of the last triangular switch. The switching network of Fig. 2 is a full access two-stage switching network having a capacity of 128 PCM links. This network contains 16 partial access blocks, from 1 to 16, in the first stage, and 15 triangular switches, from 18 to 32, in the second stage. Each of the switching blocks in the first stage contains a pair of triangular switches, from 1′, 1″ to 16′, 16″. Each of the triangular switches in the network has a capacity of 16 PCM links. In each block in the first stage, the first 8 PCM links of the first switch of the pair are connected to the first 8 PCM links of the second switch of the pair, and this PCM links constitute the terminals of the switching network, what results in the total capacity of 8 x 16 128 PCM links. The remaining PCM links in the blocks 1 to 16 are used for connections with the switches 18 to 32 of the second stage 17. The switching network shown in Fig. 2 comprises 47 triangular switches arranged in two stages, while the networks, which have been previously known, contained a minimum of 60 such switches. The partial access blocks can also be used in networks containing more than two stages. In case of the network having the capacity of 2048 PCM links composed of triangular switches containing 8 PCM links each, a previously known network contains 24439 switches and comprises seven stages, while a network having a partial access blocks contains only 9552 switches and has three stages.

Claims: 1. A one-sided multistage switching network composed of one-­ sided switching blocks arranged in stages, characterized in that the input stage contains partial access switching blocks, some of the terminals of which can be connected to other terminals of the block, and these terminals constitute the terminals of the switching network, while the remaining terminals of the block are used for connections with switching blocks of the next stage of the network. 2. A one-sided multistage switching network according to claim 1, characterized in that the first stage is arranged in blocks (1 to 16), each block contains two triangular switches (1′, 1″ to 16′, 16″), and the half of the terminals of the first triangular switch (1′ to 16′) of the pair is connected to the half of the terminals of the second switch (1″ to 16″) of the pair, and these terminals constitute the terminals of the switching network, while the remaining terminals in the blocks (1 to 16) are used for connections with the switches (18 to 32) of the second stage (17).

Inventors: JAJSZCZYK, ANDRZEJ, KABACINSKI, WOJCIECH
Applicants: POLITECHNIKA POZNANSKA
Application year: 1989
Main classification: H04Q11
IPC codes: H04Q3