RU2530673C1 - Time-spatial switching method - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: time-spatial switching method consists in the following: a switched telephone signal is received in incoming communication lines; the corresponding signal is connected in the form of a binary code, which accompanies the above switched signal and determines an intermediate path of a digital switching system on each link of spatial switching step; free intermediate paths of the switching system are searched for; lines of calling and called subscribers are connected. First, the number of intermediate lines of the switching system is reduced; an occupancy index of the intermediate line of the switched telephone signal received in incoming communication lines is recorded to the memory in the form of a binary code; and at repeated reception of a new switched telephone signal in incoming communication lines, there read are values of the occupancy index of the intermediate line from the memory; in case it is available, establishment of connection is rejected, and when the occupancy index of the intermediate line is absent, connection of lines of calling and called subscribers is performed.

EFFECT: load reduction of a computer of a digital switching system.

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Description

The space-time switching method relates to the field of telecommunications, namely to channel switching methods, and can be used to build digital switching systems.

A known method of switching in integrated information networks, implemented in RF patent 2030838, "Method of automatic switching in a communication network and a system for its implementation", class H04M 3/42, published on 03/10/1995. The method consists in the fact that the system contains one switching node, N terminals of subscribers with discrete information, K terminals of switching with analog information, K terminals of subscribers with analog information, 2m data channels 2n channels of analog information, one station computer, (N + K + 2n + 2m + 1) interface units, (N + K + 2n + 2m + 1) station sets of data transmission equipment (ADP), (N + K + 2n + 2m + 1) communication lines of interface units with standard ADF sets, (N + K) communication lines of station sets of ADF with remote sets of ADF, one channel control switch physical channels (KFK), (N + K) remote sets of ADF, one peripheral set of ADF, K communication lines of terminals with analog information with KFK, one KFK, one communication line of the peripheral set of ADF with KFK, N communication lines of terminals of subscribers with discrete information with remote sets of ADF, K communication lines of switching terminals with remote sets of ADF. Thus, an increase in the efficiency of using the communication network is achieved by providing the possibility of transmitting priority groups of analog information via PM channels. Thanks to the introduction of additional KFK and analysis in the network nodes of the “Speech” sign and the “Consent” and “Disconnect” signs, the goal is achieved.

The disadvantage of this method is the rather low efficiency of using communication channels when switching in integrated information networks.

A known method of temporary grouping, implemented in RF patent 2073955, "Device for temporary grouping", class H04J 3/22, published on 02.20.1997. The method consists in the fact that instead of two or multi-stage conversion with asynchronous pairing of input digital streams, in each of which it is necessary to generate stuffing commands, a one-stage asynchronous conversion of input streams with the formation of stuffing commands in only one step is proposed - an asynchronous input stage, and all further transformations (combining and separation of digital streams) are carried out synchronously, where the formation of staffing teams is not required. The proposed principle of combining-separating digital streams can significantly reduce the amount of equipment (reduce intermediate blocks of asynchronous coupling, clock receivers, blocks of generator equipment, blocks of butt devices), thereby increasing the reliability of the device, as well as increasing the noise immunity and reliability of the device by reducing the number of steps the formation of staffing commands, each of which is subject to interference in the transmission paths and introduces a component of the interference degradation stability of the device as a whole.

The disadvantage of this method is the high complexity and low noise immunity with a hierarchical increase in the following stages of conversion.

The closest in technical essence to the claimed method is the “Method of spatio-temporal switching” according to the patent of the Russian Federation No. 2458383, IPC G06F 7/02 (2006.01), H04J 3/00 (2006.01), publ. 08/10/2012 Bul. Number 22.

The method consists in performing the following steps: when finding free intermediate paths of a switching system providing connection of lines of the calling and called subscribers, control signals in binary code accompany the corresponding switched telephone signals during their transmission along the intermediate paths of the digital switching system from the moment of incoming communication lines until they are issued to temporary channels of outgoing communication lines, and at the input of a digital switching system to each dial-up telephone signal is connected with a corresponding signal in the form of a binary code accompanying this dial-up signal and determining the intermediate path of the digital switching system at each link of the spatial switching stage, while the switched signals consist of sequences of multi-bit words containing the control and information parts, the control (address ) the part is the binary code of the control signal, and the information is the binary code of the switched telephone th signal, and as control signals use the addresses of the temporary channels of the outgoing communication lines.

The disadvantage of the prototype method is the relatively high load of the computer of the digital switching system, when the connection is established due to the presence of several stages of switching and a sufficiently large number of intermediate paths between them needed to connect the lines of the calling and called subscribers in the switching system.

The purpose of the claimed technical solution is to develop a method of spatio-temporal switching, which reduces the load on the computer of the digital switching system by reducing the intermediate paths between the switching and fixing stages used, followed by exclusion from processing in the computer, when connecting the lines of the calling and called subscribers.

In the claimed invention, the goal is achieved by the fact that in the known method of space-time switching, which consists in the fact that they receive a switched telephone signal on incoming communication lines, attach the corresponding signal in the form of a binary code accompanying this switched signal and determining the intermediate path of the digital switching system at each link of the spatial stage of switching, they search for free intermediate paths of the switching system, connect the lines of the calling and called of subscribers, further reduce the number of intermediate line switching system. The busy indicator of the intermediate line of the switched telephone signal received on the incoming communication lines is recorded in binary memory. When re-receiving a new switched telephone signal on the incoming communication lines, the values of the busy indicator of the intermediate line are read from the memory, and if there is one, the connection is refused, and in the absence of the busy indicator of the intermediate line, the lines of the calling and called subscribers are connected.

Thanks to the new set of essential features in the claimed method, the indicated technical result is achieved by reducing the intermediate paths between the switching and fixing stages used, followed by exclusion from processing in the computer, when connecting the lines of the calling and called subscribers.

The claimed method is illustrated by drawings, which show:

figure 1 is a diagram of a digital switching system that explains the fixation order of the used intermediate paths, with the subsequent exception from processing in computers, when they are reduced;

figure 2 - block diagram of the algorithm of the method of space-time switching;

figure 3 - dependence of the number of channels of a digital switching system on the number of groups of the switching field in case of inaccessible and fully accessible construction of the system.

The implementation of the claimed method is explained as follows. Recently, due to the reduction in size and the cost of microcircuits implementing switches, it has become possible to apply the principle that each source connected to the input can be connected to a source connected to the output to build stations of sufficiently large capacity (over 2000 inputs / outputs) . However, for modern stations with a capacity of tens and hundreds of thousands of numbers, such a matrix simply cannot be performed [Switching in communication systems and networks. Berlin A.N. - M.: Eco-Trends, 2006, pp. 91-94].

Many important switching applications use software methods that are implemented on computers. They are equivalent to the method using a fully accessible circuit. But with large capacities, the computer cannot provide service for incoming call flows. Therefore, at the software level, the search for solutions equivalent to multi-link switching is required. It should also be noted that for inter-office lines, the cost of which is very high, it is necessary to increase the intensity of use and thereby reduce the requirements for the number of lines allocated for a given group of subscribers. Under these conditions, the problem arises of developing new methods of switching, using which would reduce the load on the computer and increase the efficiency of using intermediate paths of the digital switching system.

The implementation of the claimed method can be illustrated by the example of a circuit of a digital switching system shown in (Fig. 1) and a block diagram of an algorithm (Fig. 2).

Initially, the number of intermediate lines of the switching system is reduced (block 1 of FIG. 2), and the O'Dell method developed for inaccessible switching on (LAP) in multi-link switching systems can be used to determine the minimum required number [Teletraffic theory. Kornyshev Yu.N., Pshenichnikov A.P., Kharkevich A.D. - M.: Radio and Communications, 1996, p. 122-128].

According to the O'Dell method, the value of the loaded load Y ₀ served by a partly accessible system (NPDS) with V lines and availability D with a probability of loss P is defined as the conditional sum of the loads serviced by a fully accessible beam (Y _D ) consisting of D outputs and not fully accessible a bundle (Y _VD ) containing (VD) connecting devices (outputs of the NPDV circuit)

$$Y_0=Y_D+Y_{V-D}.\left(\mathrm{one}\right)$$

The value of Y _VD, under the condition of small losses in the NPDS, is found using the third Erlang formula, while taking into account the fact that Y _VD = Z (1-0) = Z (the executed load is equal to the incoming) and the number of outputs is equal to VD:

. $$Z=Y_{V-D}=\left(V-D\right)\cdot \sqrt[D]{P}$$

.

Hence, expression (1) can be written as

$$Y_0=Y_D+\left(V-D\right)\sqrt[D]{P}.\left(2\right)$$

From relation (2), we can obtain expressions for V and P in the following form:

$$V=D+\frac{\left(Y_0-Y_D\right)}{\sqrt[D]{P}}=\frac{Y_0}{\sqrt[D]{P}}+\left(D-\frac{Y_D}{\sqrt[D]{P}}\right).\left(3\right)$$

и $$\left(D-\frac{Y_D}{\sqrt[D]{P}}\right)=\beta$$

, из (3) получимMarking $$\frac{\mathrm{one}}{\sqrt[D]{P}}=\alpha$$

and $$\left(D-\frac{Y_D}{\sqrt[D]{P}}\right)=\beta$$

, from (3) we obtain

$$V=\frac{Y_0}{\sqrt[D]{P}}+\left(D-\frac{Y_D}{\sqrt[D]{P}}\right)=\alpha \cdot Y_0+\beta .\left(\mathrm{four}\right)$$

In this case, the probability of loss will be equal to

$$P={\left(\frac{Y_0-Y_D}{V-D}\right)}^D.\left(5\right)$$

The expressions for determining the coefficients α and β are tabulated and the table [Teletraffic theory. Kornyshev Yu.N., Pshenichnikov A.P., Kharkevich A.D. - M.: Radio and Communications, 1996, p.266].

At the initial reception of the switched telephone signal (block 2-3 of FIG. 2), the required intermediate path between the steps of the switching system connecting the lines of the calling and called subscribers is determined. In the block for occupying the intermediate lines (Fig. 1), the number of the occupied intermediate lines (i.e., the number of the temporary channel of the central bus) is formed as a binary code [Switching in communication systems and networks. Berlin A.N. - M .: Eco-Trends, 2006, p.126-130]. After that, this code (the busy indicator) is recorded in the memory block (block 4 of figure 2).

Subsequently, upon receiving the next switched telephone signal (block 5 of FIG. 2), the required intermediate path between the steps of the switching system and the presence of the busy indicator of this intermediate line (block 6, 8 of FIG. 2) in the recognition unit for busy indicators of the intermediate line, which is formed when comparing the current values of the busy pointers and the incoming connection request.

If it is determined that the required intermediate path is busy, then the connection between the calling and called subscribers is refused (the call is considered lost).

If there is no busy indicator of the required intermediate line, then repeated steps are taken (block 3, 4 of FIG. 2) to determine a new intermediate path between the steps of the switching system connecting the lines of the calling and called subscribers, and writing it to the memory unit.

The achievement of the technical result is illustrated as follows. For the prototype method in the fully accessible construction of the system, the dependence of the number of channels of the digital switching system on the number of switching field groups is presented in Fig. 3. For the proposed method, the determination of the number of channels is carried out taking into account possible losses and can be calculated by the O'Dell method:

1. The load served by all lines of the partially accessible beam at a given loss rate P = 0.001, Y ₀ = Z · (1-P) = 10 · (1-0.001) = 9.99 Earl. This loss rate is determined in accordance with the standards specified in the main technical requirements, which are mandatory in the design of switching systems [Norms of technological design. Urban and rural telephone networks. RD 45.120-2000. NTP 112-2000, Ministry of the Russian Federation for Communications and Informatization, 2000, p. 22, 78].

2. The load applied to the V = D lines of the fully accessible beam for a given loss rate P = 0.001 is determined from the tables Palm Z = f (V = D, P) Z = 3.1 Earl.

Load serviced by D full beam lines

Y _D = Z · (1-0.001) = 3.1 · (1-0.001) = 3.097 Earl.

3. Using expression (3), determine the required number of lines V

. $$V=D+\raisebox{1ex}{$\left(Y_0-Y_D\right)$}\!\left/ \!\raisebox{-1ex}{$\sqrt[D]{P}$}\right.=10+\frac{9.99-\mathrm{3,097}}{\sqrt[10]{0.001}}=23.5=24\left(l\mathrm{and}n\mathrm{and}\mathrm{and}\right)$$

.

In this case, the difference in the number of required channels of the digital switching system is less with an inaccessible system design and actually does not depend on an increase in the number of switching field groups (on increasing the capacity of the switching system), in contrast to a fully accessible system, which achieves the technical result.

Thus, the claimed method by reducing the intermediate paths between the switching and fixing stages used, with the subsequent exception from processing in the computer, when connecting the lines of the calling and called subscribers, allows to reduce the load on the computer of the digital switching system during space-time switching.

Claims (1)

The method of space-time switching, which consists in receiving a switched telephone signal on the incoming communication lines, attaches the corresponding signal in the form of a binary code accompanying this switched signal and determining the intermediate path of the digital switching system at each link of the spatial switching stage, find free intermediate paths switching system, connecting the lines of the calling and called subscribers, characterized in that they first reduce the number of the daily lines of the switching system, write in memory in the form of a binary code a busy indicator of the intermediate line of the switched telephone signal received on the incoming communication lines, and when re-receiving a new switched telephone signal on the incoming communication lines, read the values of the busy indicator of the intermediate line from the memory, and in the case its availability is refused to establish a connection, and in the absence of an indicator of busyness of the intermediate line, the lines of the calling and called subscriber are connected at.

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