MXPA93000695A - Oriented switch to bits, general digital switch and transmission system - Google Patents

Abstract

The present invention relates to a digital switch oriented bits comprising means (SPMI, ..., SPMS, WSW1, ..., WSW8, WCM1, ..., CMS, WM1, ..., WM8; BSW1,. .., BS28; BCM1, ..., BCM8; BM) to control the change of the position of the bit and of the word PCM of chosen bits and of groups of bits in PCM words received by the switch

Description

ORIENTED SWITCH TO BITS, GENERAL DIGITAL SWITCH AND PCM TRANSMISSION SYSTEM INVENTOR: WALTER GHISLER, Swedish, domiciled in Bátsmansvagen 21, S-19441 Upplands Vasby, Sweden, cedes all rights to TELEFONAKTIEBOLAGET LM ERICSSON society duly organized and constituted in accordance with the Laws of Sweden, domiciled at S-126 25 Stockhom, Sweden, for the invention that is described below.

SUMMARY OF THE INVENTION A digital bit-oriented switch comprising means (SPMI, ..., SPMS; WSW1, ..., WSW8; WCM1, ... CMS; WM1, ... WMS; BS 1 is described. , ..., BS28; BC 1, .... BCM8; BM) to control the change of the bit pointer and the PCM word of chosen bits and groups of bits in PCM words received by the switch. The switch is suitable to be combined with a conventional word-oriented switch to allow flexible connection of both whole PCM words and parts thereof. This switch also makes it possible to define a digital PCM transmission system, in which the words PCM can contain one or more traffic channels and in which said traffic channels can occupy a group of bits containing at least one bit, but not an entire PCM word, are distributed dynamically in the space required in an arbitrary location available in PC words. (Figure 4) TECHNICAL FIELD The present invention relates to a digital switch oriented to bits, a digital general switch and a PCM transmission system in which said switches can be used. BACKGROUND OF THE INVENTION The PCM transmission systems (PCM = Cc Modulation> Pulse Code), for example telecommunications systems, are characterized by the fact that the information in digital representation is transr.ite in time slots. Each time slot transmits a predetermined number of bits, usually 8 bits. In conventional telephone systems, this is 8 bits reserved for a channel. A predetermined number of said timeslots (32 in Europe, 24 in the United States) are transmitted on a common PCM transmission link. In other words, a channel has access to a certain slot of time, after which the channel becomes "silent" while the other channels have access to the respective slot. After the mentioned predetermined number of slots, the channel has access to the time slot. Such a PCM transmission link, for example a "PCP primary mulriplex" in accordance with the CCITT Recommendation G732, G733, has a transfer rate of 64 kbit / s (both in Europe as in the United States: - In mobile telephony digital, the spoken information is encoded by a word coder in such a way that a lower transfer rate is obtained at the radio connection, for example, in the GCM system, a transfer rate of less than 16 kbit / s is obtained. which represents a quarter of the normal PCM transmission rate.In this case, one of the channels occupies only two bits in a PCM word.To prevent the remaining bits from being unused, it has therefore been suggested that four encoded channels are assemble a PCM word that is sent to the public telephone network, etc. Eete eneamble can, for example, be carried out in a mobile services switch center. half rate "with a transfer rate of less than 8 kbit / e, which will require only 1 of the 8 bits in a PCM word. In this case, it would also be desirable to join several channels of "half rate" in the same word PCM. In addition, it is anticipated that the seven cable telephones will use mae and mae radio connections frequently also on the network of the same subscriber, in which the same code for the words can be used as in the case of mobile telephony. In connection with the transfer of terminal radie to terminal radie in talee eietemae and in eietemae cellular, it would be desirable to keep the coding compact during the entire transfer path. The data record with data rates less than kbit / e have been connected in PCM networks using the uec of words available in a multi-stuctural configuration (see recommendation CCITT V.100). Nevertheless. Multiple structures introduce delays that may be tolerable for data but not for oral communication. For this reason, the transmission of the hat with transfer rates lower than 64 ktit / s should preferably use one or doebit in a PCM channel instead of a word in a PCM multiple structure. Therefore, the need for the arbitrary traceability of part of a PCM word must be such that the 8 bits of the word are maximized. This requires a bit-oriented switch as a supplement to the switches that are oriented towards words that are currently in use. The Patent E.U.A. No. 4 718 058 presents a general switch capable of connecting both word level and bit level. However, this complicated general switch is designed to replace the existing switches with bit-level interrupting capability. Therefore. nc is designed to complement the existing switches with connection capability at the bite level. -4 ___ H SUMMARY OF THE INVENTION Accordingly, an object of the present invention is a bit-oriented switch that allows the combination of several channels occupying only a part of a PCM word in new words PCM for the transfer by the public telephone network . According to the present invention, this object is achieved by means of a switch comprising (a) N speech memories, where the number of bits in a PCM word is stored, for storing the received PCM words and N copies of the word. same; (b) a means for controlled ection of a PCM word from each diecureo memory; (c) N word memories to store the selected PCM words; and _ > (d) a means for the controlled selection of one bit of each word memory to form a new PCM word come-out of said digital switch oriented bite. Another object of the present invention is a general digital commutator for PCM traction equipment. According to the invention, said switch comprises a word-oriented digital switch for connecting whole PCM words and at least one digital switch oriented towards it to receive words PCM of said digital switch oriented to speech, to change the position of the bit and the PCM bit and group words of bits selected in the received PCM words and to provide this new PCM word to said speech oriented digital switch. BRIEF DESCRIPTION OF THE DRAWINGS The invention, together with the other objects and sale thereof, is better understood with reference to the following description in combination with the accompanying drawings, in which: FIGURE 1 shows a general digital switch of conformity with the invention comprising both a digital switch oriented towards speech and a digital switch oriented towards bite; FIGURE 2 shows the formatting of the different parts of the general digital switch in Figure 1. FIGURE 3 shows an example of how PCM word parts can be put together in the digital switch oriented to bits of the general digital switch in the figure 1; and FIGURE 4 shows a preferred embodiment of a digital switch oriented to bits in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES Er. The different figurae loe miemos reference number designate corresponding elements. Figure 1 shows a general digital switch according to the present invention. This switch can, for example, be part of a mobile services switching center. The switch comprises a digital switch oriented to conventional words S, for example a GSS unit (Sub-system of Select Group) in the AXE system of LM Ericseon. Suitable switching tools include, for example, the type that belongs to the eXectors of the AX group. The switch SW is located on an ETC terminal circuit connected to the public telephone network and to the base stations BS1, BS2, respectively. In the example only base stations are shown, but in practice there may be more taee stations. The interchange is controlled in a conventional manner by regional RP processes and a central CPS processor. In Figure I, the types of signals that occur in various parts of the seventh have been marked with the number i-in the corresponding arrows. Lae double-pointed arrows symbolize communication that can be presented in amtae directions, while lae arrows with a single tip symbolize communication only in the direction ß ^. indicated. The format of the different signal types in the figure 2 is shown in Figure 2. The type of signal 1 is the most general type of signal and includes all the AF categories in Figure 2. In this category A refers to conventional PCM channels that occupy a whole word. Category B refers to a PCM word that contains a channel that occupies only two of the eight bits of the PCM time slot. The remaining bites are not valid. Similarly, category C contains a channel occupied by Eola. vih fci *; Ptic-.f -. + Í _ip tí'_ií_. if_.te s-i? sts. bit & reetantee in laia í- síhui- piμ 4 -fc. & .ííipf- 'P'H r. they use. The category D fi.i-.f_-fc __. I_.r _.-. _._ is + .í ': ífttialeE nextE, each contains two bits, therefore it is a whole PCM word. Similarly, category E displays a PCM word filled with eight one-bit channels each. Finally, category F displays a PCM word filled with different types of compact channels, namely channels that occupy a bit and also channels that occupy doe bite. In the upper left part of figure 1, the switch SW is in an ETC terminal circuit connected to a public telephone network. Here, all the categories of A-F can be preempted, that is, the input and output modules are type 1. The upper right corner of FIG. 1 contains the battery stations BS1 and BS2. These transfer items from _ * type 2 On ETC terminal circuits from and to switch S, respectively. The signal type contains only the signal categories in the D-F packet, ie signals in which varioe canalee shares a PCM word. The mobile services switching center of FIG. 1 also contains an FTRANS transcoder for joining / dividing the "full rate" channels, ie channels that require only doe bite per PCM word. In FTRANS units, they can receive four units of type 6.

If these signals are of category A, they are compressed in FTRANS and return to the switch SW in the form of word of signal type 4, that is to say of category D. The signals already compressed of category B are received by the FTRANS unit and the eneamblan There is an additional component in the signal category D. A reverse division of type 4 signals to the output signal of type 6 can also be carried out in the FTRANS unit. Similarly, there is an HTRANS unit for joining "average rate" channels, where each unit can receive eight samples of tip 7 and assemble it into a common PCM time slot. The separation is also made in the other direction. The mobile service switching centers described above are now characterized by the fact that only full PCM words can be processed in the SW switches. It's true I KNOW that the compressed signals of the tipc system can join together in FTRANS and HTRANS, but this can not be encrypted. arbitrary form. In order to get signals to be mixed, they must be combined at the bite level in order to be combined at word level. According to the invention, the general switch of FIG. 1 therefore includes a digital switch oriented to bits BSW. On the SW-oriented switch this switch oriented bit array receives bits of type 3 on different input line, ie BF category signals of Figure 2. These signals contain different mixes of compressed channels that require less than one whole PCM word . The purpose of the digital switches oriented towards BSW bits is to change the bit and word PCM poo to eetoe channel to bit-er level. at the word level. and therefore send type 2 signals to commutators oriented towards words S. The way you do this is described in more detail with reference to the figure. Figure 3 shows an example of how the PCM word parts can be put together in a digital switch oriented to bits of Figure 1. Time slots PCM SI and S from the base station BS1 per the switch oriented towards SW words they reach ei - ^ _ ^ _ switch oriented towards bite BSW in, for example, the upper input line to the switch BSW. In a similar way, doe slote of time S? and S? from the BSE station BS2 through the word oriented switch SW reach the switch oriented towards BSW on the lower input line towards the switch EEW. However, it should be noted that it is neccesary that, for example, the ESI PCM words reach the top line. c "In a switch oriented towards word S, a PCM word from an arbitrary source can be connected to an arbitrary input of a switch oriented towards bits BSW In a switch oriented towards bite BSW, the relevant bits of the compressed channels that one wishes to combine in a new time slot PCM S5 are extracted, and said time slot is sent back to the SW-oriented switch to connect to the public telephony network, in other words, the bit oriented switch BSW provides the possibility to optimize In the example of Figure 3, the PCM links come from the baee stations, however, a BSW-oriented digital switch can also receive public telephony network signals. The entire category of the BF categories can be read in. Figure 4 shows a preferred mode of a switch The Pite-oriented digital signal in accordance with the present invention is suitable for use in a general digital switch of Figure i. The digital bit-oriented switch of the figure comprises a speech memory SPMi which is continuously supplied with time slots of the input PCM transmission links, PCM1 and PCM2. For example, in the European PCM system, the last 32 time slots of the transmission link PCM1 and PCM1 will therefore be available in the speech memory SPM1.

* In addition to the disk memory SPMl, the switch of the tifei-M-fi __ also speech memory SPM,,,. , SPM8, that is seven additional speech memories. In this speech memory, copies are stored 3 &rdnurss time in Id memory of speech SFMí At this time, therefore, there are no dialects or: -i.:. I &_ _ of 6¿. PCM time slots. The switch of figure 4 also comprises eight word control memories WCM1, WCM2 WCM8. Eetae control memories control the WSWl switches remotely, WSW2 WSW8 for the output of one of the 6¿ + PCM time slot 'of speech memory pock SPMl, SPML SPM8. To achieve this purpose, the word control memory contains 32 mem- ery cells, each containing eeie bite (2 (6) = 64 possible addresses in the • ß ___. L ^ l memory of discurec SPMl. SPM2 SPM8 .. Eetae memcriae word control ee controlled by control signals from the RP regional processors and from the CPS central processor system. If one needs to combine mae de doe PCM transmission link. For example four links, the length of the memory can be extended to 128 memory cells. At the same time, the length of the word in the word memory has to expand to 7 bits. However, the cell number in the word control memory * It continues to remain of 32 cells, but the BSW-oriented switch provides only one PCM tram link. Another possibility of combining a four-link bite is to let the SW-oriented switch select the PCM words in question and send these words to a BSW oriented towards each entry line. In certain cases, for example, only assembled PCMs must be connected, the bite-oriented switch can also be provided with only one input and one output. However, one reason why the bite-oriented switch preferably has fewer outputs than inputs (ie, it performs traffic concentration) is that the output contains assembled PCM information, in dc >where the maximum number of bits in the same word is used, while nc. all loe bite e? ___. ^^. in the input PCM words they need to contain information and therefore not all the bits are connected to the output PCM words. The words selected from the speech memories are transferred to the word memory WM1. WM1, ..., WMS. From the eight words obtained, a bit pointer is selected for each word by means of the switches BSW1, BSW2, ... BSW8 controlled by control memory of bite BCM1, BCM2"BCM8.Eetae control memories are also controlled by process regional loops and the central processor CPS, which in this case selects only one bit of each word of the memory cell in the word control memory BCMl, BCM2, .... BCM8 contains only three bits. These are collected in a BM bit memory which stores the formed time slot of the output PCM transmission link PCM3.F The necessary cyclic control procedure of the speech and control memories is well known to the person skilled in the art and ee. This is done, for example, in the manner described in the AXE system documentation Network signaling can be done in accordance with the CCITT No. 7 signaling system. several bits in an input PCM word to a switch oriented to bite BSW must be transferred to an output PCM word. the input word is selected several times from the speech memory SPMl, SPMl, .... SP, so that each bit can be selected from a respective copy. However, if the various bits of an input PCM word to a BSW-oriented switch are to be distributed over several output PCM words, the input word PCM selects repeatedly from the speech buffer SPM1, SPM2, ..., SPM8 with a time duration of one or several time slots. It should be noted that the traceability eelection between subscribers should be treated separately in the BSW-oriented switch, in contrast to the normal PCM word connections, where the address years share the same control memory information (see for example the AXE GSS documentation). The speech-oriented switch according to the present invention also provides the possibility of semi-permanent connections through the speech connection network with a transfer rate of 6 kbit / s, but divided into connections of less than 64 kbit / e. For example. a PCM channel, from a mobile service connection center to another mobile service connection center through the public telephony network may be used for eight connections of the "average rate" network channel between the mobile service connection centers. When a call is terminated, a bit position becomes available in the corresponding PCM word and can be assigned to a new call between the mobile service hubs without requiring a new 6 ^ kbit / e connection to be established. Therefore. the division of the word PCM can connect to a sub-ultiplex. The advantage of semi-permamentee cenexionee of 6 kbit / e is that the network in question has previously only connected 64 kbit / s and not the slow channels. If connection is made between the mobile telephone service connection center of the same brand, a specific signal from a vendor can be used, - assuming that the establishment of a semi-permanent 64 kbit / e connection can be carried out in accordance with the present CCITT signaling system No. 7. If, however, a connection between mobile service connection centers of different brands is desired, an additional standard, for example, in the CCITT signaling system No. 7 is required for signaling necessary Based on the above description it can be seen that the bite-oriented switch according to the present invention allows an arbitrary change of position and PCM word for bit or bite groups that do not fill a complete PCM word. This makes it possible to define a totally new digital PCM transmission system in which the traffic channels occupy a group of bits containing at least one bit. but not an entire PCM word, they are placed dynamically in the space required in an arbitrary available poetry in word PCM. For example It is possible to define traneito channels that contain tree or five bit positions in a PCM word. Eetoe new channels, in the digital switch oriented towards bite in accordance with

Claims (4)

1. The present invention can be combined with compressed traffic channels already defined for transfer in the conventional speech oriented PCM tracing link. If a BSW word-oriented switch is not efficient for forward or forward traffic loading, one or several switches can be set to bite or the traffic can be directed to another node with i * _ switches oriented towards bite. It will be understood by those skilled in the art that various modifications and changes may be made to the present invention without regard to the spirit and scope thereof, which is defined by the appended claims. NOVELTY OF THE INVENTION Having declared the present invention, it is considered a novelty, and therefore, the content of the following CLAIMS is claimed in property 1. A digital switch oriented towards bite for PCM transmission systems, to control the change of bite position and bite PCM word and bite groups referred to in PCM words, received by said switch, characterized in that (a.}. N eighteenth-day memory { SPMl, ..., SPM8), where N ee the number of bits in a word PCM, to store the words PCM received (SI, ..., S4) and Nl copies of the same; (b) mediae (WSW1, .... WSW8; WCM1, .... WCM8) for the controlled selection of a PCM word from each diecureo memory; (c) N word memory (WM1, ... WM8) to store the selected PCM words; and id) medioe (ESWi, ..., BSW8; BCM1, ..., BCMS) for the f X? controlled control of a bit of each word memory (WM1, ..., WM8: to form a new word PCM as output of said digital switch oriented towards bite 2. A digital switch oriented towards bite according to claim 1, characterized in that said word PCM comprises eight bits, ie N = 8. 3. A general digital switch for PCM transmission system to connect PCM word both at the level BBP5 ai cTr i. zix s piv í o LITO. ? zé- Ü II "• ___: word-oriented digital switch (SW.) to connect entire PCM words and at least one digital-oriented switch has bite (BSW; connected to it to receive word P1K) of dcnc digital switch orier.tac: to words (SW.}., to change the bit position and the word P of rite selected and group of bite in the words FCM reoieidas (Yes, S2, S?, S¿- • and for the output of new PCM words to these switches Digitally oriented words (SW). Four . A general digital switch according to claim 3, characterized in that digital switches oriented to additional bits (BSW) are connected to said word-oriented switch (SW) when the bit-level connection demand is increased. In testimony of which, I have signed the previous description and novelty of the invention as agent of TELEFONAKTIEBOLAGET L M ERICSSON, in Mexico City, Federal District, today, February 9, 1993. p.p. of TELEFONAKTIEBOLAGET L M ERICSSON EDUARDO CORREA E.