KR950005590B1 - Echo elimination device of an electronic exchanger - Google Patents

Abstract

The echo cancelling device comprises the ASP(23) deciding whether the echo cancel operation is needed or not; the control interface(20) interfacing between the ASP(23) and the TSP(19); the time switch device(16) operating switching function in response to the ASP(23) and the TSP(19); the echo cancelling circuit(15) performing echo cancelling function by the control signal from the TSP(19); the repeater interfacing circuit(17) connected to the DTIP(22) and the control interface(20) to communicate with the PSTN; the signal service circuit(18) generating many kinds of tone signals; the signal service processor(21) sending the message received via the signal service circuit(18) to the corresponding processors by way of the control interface(20).

Description

Telephone network echo cancellation device and operation method by interworking with switch network

1 is a block diagram according to the present invention.

2 is a detailed configuration diagram of a time switch device according to the present invention.

3 is a flow chart of the present invention.

* Explanation of symbols for main parts of the drawings

1 to 8: 1K bidirectional timeslot switching circuit (TSLAx (x = 0 to 7))

9, 9-1: Time switch link matching circuit (TLIA)

10: Remote Multiple / Demultiplex Circuit (RMDA)

11, 14: control memory and maintenance circuit (CMMA)

12, 13, 19: Time Switching Control Processor (TSP)

15: echo canceller 16: time switch device

17: relay line matching circuit 20: control interface (CI)

21: Signal Service Device Control Processor (LSP)

22: relay line matching circuit control processor (DTIP)

23: connection exchange processor (ASP)

The present invention relates to a telephone network echo cancellation device and an operation method by interworking with a switch network.

In general, a long distance telephone network or a digital mobile communication network causes delays of several tens of microseconds or more due to transmission distance and voice data processing. Two-way calls are made between two subscribers and a switch in a general telephone network. Since a two-way communication path is constructed by wire, two-wire and four-wire conversion circuits are used in the subscriber matching circuit of the exchange. At this time, echo occurs due to factors such as impedance mismatch.

If there is no reverberation and only pure delay occurs, even if there are hundreds of delays, there is no great inconvenience in talking over the telephone. do. Therefore, echo cancellation is indispensable when a delay of more than a few tens of kHz occurs in the telephone network. In a telephone switching network, the echo canceller is generally located near the opposite two-wire and four-wire conversion circuit due to delay problems.

Except for international long-distance circuits, the total transmission delay in domestic circuit-switched networks currently exists within 20㎳ and no echo canceller is used. However, in digital mobile telecommunication switching network, voice coding is performed on voice data to reduce the use band for reasons of radio channel efficiency. Unlike the approach, significant processing delays occur. Therefore, the echo must be eliminated because a significant delay (100 ms or more) occurs in the digital mobile switching network when the mobile communication network and the existing circuit switching network are connected.

However, the digital mobile communication subscriber matching unit does not have two-wire and four-wire conversion, so when the voice data of the subscriber connected to the digital mobile telecommunication switching network is transmitted to the digital mobile telecommunication subscriber, the subscriber connected to the circuit switched network is not affected by the echo. However, when the voice data of the digital mobile communication subscriber is transmitted to the subscriber connected to the circuit switched network, it is echoed and returned from the two-wire and four-wire conversion circuit of the circuit matching part of the subscriber connected to the circuit network, and the echo is heard to the mobile subscriber.

Therefore, when the digital mobile communication network and the existing circuit switched network are connected, an echo canceller is used for the relay line to which the digital mobile communication network and the existing circuit switched network are connected. That is, when transmitting PCM voice data output from the digital mobile communication switch to the existing circuit switching network, the echo canceller receives the data and stores it, and impulses about delay and echo of the path that passes through the 2-wire and 4-wire conversion circuit of the circuit switching network. If the output obtained by inputting the PCM voice data stored in the digital filter in the echo canceller having the same characteristics as the response is subtracted in the direction from the circuit-switching network, the subscriber accommodated in the mobile communication switch is not affected by the echo.

Generally developed and marketed echo cancellers can be installed and used on T1 or E1 repeaters. When the echo canceller is installed on the relay line as described above, it must be installed and operated separately from the mobile communication switch, so the maintenance function of the switch itself cannot be used, which causes considerable difficulties in maintenance, and signaling or common line through the relay line. (SS No. 7) If the echo canceller, such as signal or digital data transmission, should not be operated, i.e. if the echo canceller of CCITT Recommendation G.165 is to be disabled, the echo canceller of CCITT Recommendation G.165 should be disabled. Since ring characteristics must be satisfied and additional tone detectors and disabling circuits must be provided accordingly, economy per line due to echo cancellation is reduced.

In addition, since the echo canceller is located on the relay line, there is a problem of lowering the reliability of the echo canceller, and depending on the network configuration, there is a case where echo cancellation is not required. In this case, when using the existing echo cable attached echo canceller, there is a problem that such an operation effort, such as not to disable or install the line is required.

Therefore, the present invention devised to solve the above problems, unlike the existing method of installing the echo canceller on the relay line, the apparatus for removing echo by interlocking the echo canceller with a time switch device that receives the relay line of the switch network of the exchanger And to provide a method.

In order to achieve the above object, the apparatus of the present invention includes a connection exchange processor (hereinafter referred to as ASP) for determining whether a relay call is a call requiring echo cancellation; A control interface unit (hereinafter referred to as CI) connected to the connection exchange processor to provide a communication path; A time switch control processor (hereinafter referred to as TSP) connected to the CI to control time switching; A time switch device connected to the CI and connected to an external space switch (hereinafter referred to as SSW) for time switching under the control of the SAP and the TSP; An echo canceller connected to the time switch device to transmit / receive an echo cancelation transmission / reception input / output signal, and to remove an echo in cooperation with the switch device under the control of the TSP; A digital relay line matching processor (hereinafter referred to as DTIP) connected to the CI to relay digital signals; A relay line matching circuit connected to the DTIP, connected to the time switch device, transmitting and receiving a signal, and relaying with a PSIN (Public Switched Telephone Network); A signal service device connected to the time switch device and generating various tones for signaling; And a signal service processor (hereinafter referred to as LSP) for transmitting a message received through the signal service device to the corresponding processor through the CI.

In addition, in order to achieve the above object, the method of the present invention, an echo canceller, a time switch device, a relay line matching circuit, a signal service device, a time switch control processor (TSP), a control interface (CI), a signal service device control processor (LSP) In the method applied to a telephone network echo cancellation device in conjunction with a switch network having a relay line matching circuit control processor (DTIP), a connection exchange processor (ASP), a switch for processing a relay call in the switch, ASP, TSP, After initializing the operating system (OS) and application of the processor such as DTIP, LSP, and initialization, the exchange is ready for normal call processing and the relay line matching circuit, time switch device, A first step of allocating a relay line channel for a relay call through a signaling process by a signaling service apparatus or an LSP; After performing the first step, once signaling for the relay call is completed and the assignment of the relay line to the relay call is completed, the ASP determines whether the call is a call that requires echo cancellation or not; A third step of performing call processing requiring echo cancellation, when the echo needs to be removed after performing the second step; And a fourth step of performing a call processing that does not require echo cancellation if the call does not need echo cancellation after performing the second step.

One of the basic configurations in configuring a switch network in a digital switching system is a time switch device that performs time slot interchange (TSI). The basic function of a time switch device is to swap all time slots on the input highway on any output highway.

The time switch device of the digital exchange achieves circuit switching by exchanging time slots on the multiplexed time division PCM highway with each other. That is, the voice data of timeslot 0 is transferred to TSI, and the data of TSI is transferred to TS0, so that subscribers assigned TS0 and TS1 can communicate with each other. In fact, since there are many such highways, timeslots must be exchanged between timeslots on different highways. Since the timeslot is part of the time base, the exchange of timeslots means that some voice data changes its position on the time axis and past movement to the time axis is not possible, resulting in data having a time delay.

Hereinafter, with reference to the accompanying drawings will be described an embodiment according to the present invention;

1 is a block diagram according to the present invention.

In the figure, 15 is an echo canceller, 16 is a time switch device, 17 is a relay line matching circuit, 18 is a signal service device, 19 is a time switch control processor (TSP), 20 is a control interface (CI), 21 is a signal service device control A processor LSP, 22 denotes a relay line matching circuit control processor DTIP, and 23 denotes a connection exchange processor ASP.

As shown in the figure, a control interface unit (hereinafter referred to as CI) 20 connected to the connection exchange processor (hereinafter referred to as ASP) 23 and a time switch connected to the CI 20. Time switch device 16 connected to a control processor (hereinafter referred to as TSP) 19 and the CI 20 and connected to an external space switch (hereinafter referred to as SSW) to be controlled by the TSP 19. And an echo canceller 15 connected to the time switch device 16 to transmit and receive an echo cancelation transmission / reception input / output signal and controlled by the TSP 19, and a digital relay line matching processor connected to the CI 20. A relay line matching circuit 17 connected to the DTIP 22 and connected to the time switch device 16 for transmitting and receiving signals and for relaying with a public telephone network (PSTN) (hereinafter referred to as DTIP). And a signal service processor (hereinafter referred to as LSP) 21 connected to the CI 20, and the LSP 21; And a signal service device 18 connected to the time switch device 16.

Looking at the operating process of the present invention configured as described above, the signaling (RS) is made when the relay call is established in the telephone exchange network. Signaling is performed by receiving the RS signal transmitted from the other telephone network from the signal service device 18 via the time line device 16 via the relay line matching circuit 17.

In the signaling process, the signal service device 18 generates various tones such as a called number and sends them to the signal service device control processor (LSP) 21 through the TD bus, and the LSP 21 sends a corresponding message. Through the CI 20 which is a processor communication bus, it is sent out to a required processor such as an ASP 23.

After the voice of the mobile communication subscriber accommodated in the exchange is space-switched by the SSW in the switch network via a time switch or the like, voice PCM data is input from the SSW to the time switch device 16 through the SNL (switch network link), Under the control of the upper processor SAP 23 and the TSP 19, time switching is performed, and the voice PCM data is controlled through the relay line matching circuit 17 performing the T1 or E1 relay line matching function under the control of the DTIP 22. It is transmitted to existing circuit network through T1 or E1 relay line. The voice PCM data transmitted to the existing line network is delivered to the other party through the two-line / four-line conversion circuit of the desired subscriber matching circuit through various paths in the circuit-switching network. The echo generated from the two-wire / four-wire conversion circuit in the above path is input to the relay line matching circuit 17 through the opposite direction path in the circuit-switching network and accepted by the time switch device 16, the SSW, and the mobile communication subscriber. It is delivered to the corresponding mobile communication subscriber via the time switch.

At this time, since the mobile communication subscriber is disturbed by the conversation, the mobile communication subscriber removes the same direction as the time switch device 16 and the echo canceller 15.

2 is a detailed configuration diagram of a time switch device according to the present invention.

In the figure, 1 to 8 are 1K bidirectional timeslot switching circuits (TSLA), 9 and 9-1 are time switch link matching circuits (TLIA), 10 are remote multiple / demultiplex circuits (RMDA), and 11 and 14 are control memories. And maintenance circuit CMMMA, 12, 13 represent a time switch control processor TSP, respectively.

As shown in the figure, the time switch device is a time slot switching circuit (hereinafter referred to as TSI) for performing an interface with a multiplexed PCM subhighway, a multiplex / demultiplex, a TSI function, a code conversion function, etc. ( 1 to 8) and a time switch link matching circuit connected to the TSIAs 1 to 8 to perform optical matching, data selection and multiplexing conversion, and interprocess or communication (IPC) matching function (hereinafter, referred to as TLIA). (9, 9-1) and a remote multiple / demultiplex circuit used in place of the TLIA (9, 9-1) when the time switch device is used in a remote switching system and is matched via a T1 / E1 link. Control memory and maintenance circuit (hereinafter referred to as CMMA) consisting of a loopback through internal jitter, a common control memory for transmission direction, and the like, between the subscribers accommodated in the same time switch device. 11, 14) and the times configured as above It consists of a time switch control processor (TSP) (12, 13) for controlling the device value.

The time switch device is configured in both directions, and in the transmission direction, it receives an input of up to 4K and outputs it to an output of 1K. In addition, when the above two time switch devices are used, an input of up to 8K can be received and exported to an output of 1K. That is, up to 8: 1 aggregation is possible.

3 is a flowchart illustrating the operation of the echo canceller by interlocking with a switch.

The exchange performs an operating system (OS) and application program initialization of processors such as various processors ASP (23), TSP (19), DTIP (22), and LSP (21) for relay call processing. After the initialization is completed, the exchange is ready for normal call processing, and the call is performed by the relay line matching circuit 17, the time switch device 16, the signal service device 18, the LSP 21, or the like regardless of the incoming call or the outgoing call. The relay line channel is allocated to the relay call through the signaling process (25) (the echo canceller 16 is not involved at all in the signaling process).

Once signaling for the relay call is completed and relay line allocation for the relay call is completed, the ASP 23 determines whether the call is a call requiring echo cancellation or not (26).

In the case of a call requiring echo cancellation according to the result of the determination 26, the bidirectional empty channel is selected from the arbitrary channels of the echo canceller 15 under the control of the TSP 19, and the time is controlled by the control of the TSP 19. Path configuration between the call channel at position 16 and the selected echo canceller 15 channel is performed by time switching and call processing (27, 28).

When the path configuration between the echo canceller 15 and the time switch 16 is completed, the SNL transmission signal, the time switch 16, the echo cancellation transmission input signal, the echo canceller 15, and the echo cancellation transmission are performed in the switch path configuration 28. Output signal, time switch 16 transmission signal, relay line matching circuit 17 reception signal, time switch 16, echo cancellation reception input signal, echo canceller 15, echo cancellation reception output signal, time switch 16, The switch path configuration such as the SNL received signal is made by time switching of the time switch 16 under the control of the TSP 16.

Voice data passing through the echo canceller 15 is transmitted to the filter applied to the selected channel of the echo canceller 15 when transmitted in the above path, and is input to the echo canceller 15 through the echo canceling received input signal upon reception. Echo cancellation is performed by subtracting the output of the adaptive filter of the selected channel of the echo canceller 15 from the received PCM voice data and outputting it as an echo cancellation reception output signal.

If it is determined that the echo cancellation is not necessary in the ASP, the ASP 23 requests the TSP 19 for the path configuration request through the CI 20, and then the SNL transmission signal and the time switch 16. Transmission direction switch path configuration such as transmission signal, T1 transmission signal of relay line matching circuit 17, T1 reception signal, reception signal of relay line matching circuit 17, SN reception signal and switch path configuration of time switch 16 By the control of the TSP 16, the time switch 16 is time-switched to perform call processing (29).

Therefore, the echo canceller applied to the present invention does not require a complicated relay line interface circuit, a signaling interface circuit, a disabling circuit, etc. of a conventional commercial echo canceller, and a T1 scheme (1.544 Mbps) in which a relay line that needs echo cancellation receives 24 channels. It is possible to use any one of the E1 method (2.04Mbps) and 32 channels, that is, it can operate in conjunction with the time switch irrespective of the method of the relay line, so that an economical echo canceller can be configured and Since it is not located at the relay line, it is economical because the echo canceller can be efficiently removed with the echo canceller without degrading the reliability of the relay line.The echo canceller and the time switch are interlocked to perform echo cancellation. Reverberation agent can be arbitrarily assigned by software of control processor It can flexibly cope with the breakdown of the device, improve overall system reliability through N + 1 redundancy, and software control of the switch control processor for relay lines that do not require echo cancellation. There is an effect that can improve the operability than the method of disabling or removing the eliminator.

Claims (5)

A connection exchange processor for determining whether the relay call is a call requiring echo cancellation (hereinafter, referred to as ASP) 23; A control interface unit (hereinafter referred to as CI) 20 connected to the connection exchange processor 23 to provide a communication path; A time switch control processor (hereinafter referred to as TSP) 19 connected to the CI 20 to control time switching; A time switch device 16 connected to the CI 20 and connected to an external space switch (hereinafter referred to as SSW) for time switching under the control of the ASP 25 and the TSP 19; An echo canceller (15) connected to the time switch device (16) to transmit and receive an echo cancelation transmission / reception input / output signal, and to cancel an echo in cooperation with the switch device (16) under the control of the TSP (19); A digital relay line matching processor (hereinafter referred to as DTIP) 22 connected to the CI 20 to relay a digital signal; A relay line matching circuit (17) connected to the DTIP (22) and connected to the time switch device (16) for transmitting and receiving signals and for relaying with a public switched telephone network (PSTN); A signal service device (18) connected to the time switch device (16) for generating various tones for signaling; And a signal service processor (hereinafter referred to as LSP) 21 for transmitting a message received through the signal service device 18 to a corresponding processor through the CI 20. Telephone network echo cancellation device. The apparatus of claim 1, wherein the time switch device 16 performs an interface multiplex / demultiplex with a multiplexed pulse code modulation (PCM) subhighway, a time slot interchange (TSI) function, a code conversion function, or the like. First to eighth timeslot switching circuits (hereinafter referred to as TSIAs) 1 to 8; First and second time switch link matching circuits (hereinafter, TLIA) connected to the first to eighth TSIAs (1 to 8) to perform optical matching, data selection and multiplexing conversion, and interprocess or communication (IPC) matching functions. ), (9, 9-1); When the time switch device is used in a remote switching system and is matched through a T1 / E1 link, a remote multiple / demultiplex circuit (hereinafter referred to as RMDA) used instead of the first and second TLIAs (9, 9-1) ( 10); First and second control memories connected to the first to eighth TSIAs (1 to 8) and configured as loopback through internal jitter, transmission direction common control memory, and the like during inter-subscriber calls accommodated in the same time switch device. Circuits (hereinafter referred to as CMMA) 11, 14; And first and second time switch control processors (TSPs) 12 and 13 for controlling the time switch device 16 configured as described above. Echo canceler 15, time switch device 16, relay line matching circuit 17, signal service device 18, time switch control processor (TSP) 19, control interface (CI) 20, signal service device In the method applied to a telephone network echo canceller in connection with a switch network having a control processor (LSP) 21, a trunk line matching circuit control processor (DTIP) 22, and a connection exchange processor (ASP) 23, In the exchange, the operating system (OS) and application programs of various processors such as ASP (23), TSP (19), DTIP (22), and LSP (21) are initialized for relay call processing. After the normal call processing preparation is completed, the relay call is processed through the signaling process by the relay line matching circuit 17, the time switch device 16, the signal service device 18, and the LSP 21 regardless of the incoming call and the outgoing call. A first step (24, 25) of allocating a relay line channel for the network; After performing the first steps 24 and 25, once signaling for the relay call is completed and the relay line is allocated to the relay call, the ASP 23 determines whether the call is a call requiring echo cancellation or an unnecessary call. A second step 26 of making; After performing the second step 26, in the case of the call requiring echo removal, after performing the third steps 27 and 28 for performing call processing requiring the echo removal and after performing the second step 26, echo cancellation is not required. In the case of a call, the telephone network echo cancellation method by interworking with a switch network, characterized in that it comprises a fourth step (29) for performing a call processing that does not need echo cancellation. 4. The third step (27, 28) according to claim 3, wherein the third step (27, 28), by the control of the TSP (19) selects a bidirectional empty channel of any channel of the echo canceller (15), and by the control of the TSP (19) Interworking with the switch network, characterized in that the configuration of the path between the talk channel of the time switch 16 and the selected echo canceller 15 channel is performed by time switching and call processing (27, 28). Echo cancellation method by telephone network. 4. The method of claim 3, wherein in the fourth step 29, if it is determined in the ASP 23 that echo cancellation is not necessary, the ASP 23 requests the TSP 19 through the CI 20 to request a path configuration request. In this case, the transmission direction switch path configuration such as the SNL transmission signal, the time switch 16 transmission signal, and the T1 transmission signal of the relay line matching circuit 17, the T1 reception signal, the reception signal of the relay line matching circuit 17, and the time switch ( SNL received signal and switch path configuration of 16) is performed by the fifth step 29 which performs call processing by time switching of the time switch 16 under the control of the TSP 16. Phone network echo cancellation method by linking with.