KR100378587B1 - Apparatus for converting time division multiplex signal to atm cell and vice versa - Google Patents

Abstract

The present invention relates to an apparatus for converting a time division modulated channel-specific signal into an asynchronous transmission mode (ATM) cell or converting an ATM cell into a time division modulated channel-specific signal, wherein the ATM adaptation layer 1 assembly of the present invention is assembled. And the segmentation and reassembly (SAR) unit converts the input E1 signal into an ATM cell and provides the uplink header conversion circuit to the uplink header conversion circuit, including an index indicating the corresponding line of the input E1 signal in the ATM cell. The index converts the index in the ATM cell to the corresponding VPI and VCI and provides it to the cell bus. The downlink header conversion circuit receives the ATM cell from the cell bus and includes the index corresponding to the VPI and VCI in the ATM cell in the ATM cell and provides the AAL1 SAR unit. The AAL1 SAR unit changes the ATM cell to an E1 signal and changes the E1 signal. Provide the signal to the E1 signal line corresponding to the index in the ATM cell.

That is, in the apparatus of the present invention, the speech signal of a time division modulated channel unit can be easily restored to an ATM cell, and the ATM cell can be easily restored to the speech signal of a time division modulated channel unit again.

Description

Time division channel modulated signal and asynchronous transmission mode cell inter-conversion device {APPARATUS FOR CONVERTING TIME DIVISION MULTIPLEX SIGNAL TO ATM CELL AND VICE VERSA}

The present invention relates to an apparatus for converting a time division modulated channel-specific signal into an asynchronous transmission mode (ATM) cell and converting an ATM cell into a time division modulated channel-specific signal.

The electronic switchboard that accepts x-Digital Subscriber Line (xDSL) is composed of optical connection between host and remote device to provide xDSL service to remote subscriber, and communication between host and remote device Is performed in synchronous transfer mode-1 (STM-1) frame units. For STM-1 frame communication between the host and the remote device, the host inserts voice information (time division modulated channel signals) and ATM cells from the telephone network and the ATM network into the remote device in the STM-1 frame. The remote device also inserts voice information (time division modulated channel unit voice) from the subscriber and ATM cells into the STM-1 frame and provides it to the host. The host and the remote device separate the voice signals and ATM cells in the STM-1 frame provided from the other party and provide them to the telephone network and the Internet network (for a host) or to each subscriber (for a remote device).

Meanwhile, in the above-described scheme, in order to insert an ATM cell and a voice signal in an STM-1 frame, as disclosed in the "xDSL service apparatus having an aggregation function (application number No.)" filed by the applicant as the same as the present application. STM-1 frame should be divided into ATM cell area and voice signal area, and the size of the separated area should be fixed. In the case of dividing and fixing regions within an STM-1 frame, for example, there may be a case where the speech signal provided from the PSTN exchange is small so that the speech signal provided in the speech signal region of the STM-1 frame may be left. The transmission path is wasted.

The present applicant has applied for the "xDSL service apparatus having an aggregation function (application number No.)" which solves this problem. In the present invention, the voice signal is changed to an ATM cell, and the voice signal and ATM network (or subscriber) changed to an ATM cell. By changing the ATM cells (from) to an STM-1 frame, the STM-1 frame has to be divided into an audio signal area and an ATM cell area. Meanwhile, although the present invention needs to restore a time division modulated channel unit speech signal to an ATM cell and an ATM cell to time division modulated channel unit speech signal again, this technique is not disclosed.

Accordingly, an object of the present invention is to provide an apparatus capable of restoring a time division modulated channel unit speech signal to an ATM cell and an ATM cell back to time division modulated channel unit speech signal.

In order to achieve the above object, the present invention is an apparatus for converting an E1 signal and an asynchronous transfer mode ATM cell, and inputs a plurality of E1 signals, ATM cells are sequentially converted into E1 signals, and the header of the ATM cell. Inserts and transmits an index indicating the type of the E1 signal. The ATM Adaption Layer 1 assembly and disassembly that receives the ATM cell and generates and transmits the E1 signal according to the index in the ATM cell. SAR) (AAL1 SAR); An uplink header conversion circuit for receiving an ATM cell from an AAL1 SAR unit, replacing an index in the ATM cell with a corresponding VPI and VCI, including the header in the ATM cell, and transmitting the same to a cell bus; An ATM cell is received from a cell bus, and the downlink header converting circuit replaces the VPI and VCI in the ATM cell with a corresponding index and transmits the same to the AAL1 SAR.

1 is a block diagram of a time division channel modulated signal and an asynchronous transmission mode cell interconversion device according to the present invention;

2 is a diagram illustrating a state of conversion between a time division channel modulated signal and a payload of an asynchronous transmission mode cell in an asynchronous transmission mode cell interconversion apparatus according to the present invention;

<Description of the symbols for the main parts of the drawings>

10: conversion circuit 11, 12: E1 matching portion

12: SRTS Part 13: AAL1 SAR

20 uplink header conversion circuit 21 SAR transmission buffer

22: uplink header change unit 23: cell transmission buffer

24: cell bus matching unit 30: downlink header conversion circuit

31: cell bus matching unit 32: cell receive buffer

33: Downlink header conversion section 34: SAR reception buffer

Hereinafter, an embodiment of the present invention will be described in detail.

1 is a block diagram of a time division channel modulated speech signal and an asynchronous transmission mode cell interconversion apparatus according to the present invention, as shown, a conversion circuit 10, an up header header conversion circuit 20, and a down header header conversion circuit 30. As shown in FIG. It is provided.

Here, the conversion circuit 10 converts an ATM signal of a time division modulated channel unit (for example, 256 bits of E1) into an ATM cell and provides the uplink header conversion circuit 20 to the uplink header conversion circuit 30, as shown. E1 matching unit 11, 12, ATM adaptation layer 1 assembly and reassembly (SAR) unit (AAL1 SAR) unit for converting a provided ATM cell into an E1 signal; 13) and a Synchronous Residual Time Stamp (SRTS) unit 14.

The E1 matching units 11 and 12 are connected to a plurality of E1 lines (e.g., L1-L8), and the signals (E1 signals) from the AAL1 SAR unit 13 are 2.048 Mbps and corresponding E1 lines (L1-L8). And a physical layer for providing the AAL1 SAR unit 13 with an E1 signal of 2.048 Mbps provided through the lines L1 to L8. The E1 signal consists of 32 channels, 28 channels are voice signals, and the other four channels can be used for control signals.

The AAL1 SAR section 13 ATM-structures the E1 signals provided from the E1 matching section 11 to the uplink header conversion circuit 20 by unstructured the ATM cells. Here, the ATM cell unstructured means to cellize the signals in the channel of E1 in order by 47 bytes as shown in FIG. Here, the payload of the ATM cell is composed of 48 bytes, but in the present invention, the reason for dividing the E1 signal by 47 bytes is to use 1 byte as SRTS information in the payload section as described later.

On the other hand, the header information in the ATM cell should be assigned destination information, that is, VPI and VCI, but the AAL1 SAR unit 13 does not perform a function for allocating it. However, since the AAL1 SAR unit 13 only knows which E1 line (L1-L8) the input E1 signal is provided from, the AAL1 SAR unit 13 inserts index information indicating the E1 line (L1-L8) in the header of the ATM cell. do.

In addition, the AAL1 SAR unit 13 receives the ATM cells from the downlink header conversion circuit 30 to change the ATM cells into E1 signals (as shown in FIG. 2), and the corresponding E1 lines E1 through the E1 matching unit 12. E8). Here, the header of the ATM cell provided from the downlink header conversion circuit 30 does not include VPI and VCI information, but includes index information indicating the E1 lines L1 to L8. Corresponding E1 signal can be easily provided to the lines L1-L8.

The SAR transmit buffer 21 in the uplink header conversion circuit 20 stores ATM cells from the AAL1 SAR unit 13 as described above, and the SAR transmit buffer 21 sequentially stores the stored ATM cells. The conversion unit 22 is provided. The uplink header converting unit 22 receives ATM cells from the SAR transmission buffer 21 and converts their headers. That is, a table is configured in the uplink header converting unit 22, and VPIs and VCIs corresponding to indexes are stored in the table. Accordingly, the uplink header converting unit 22 reads a VPI, VCI value corresponding to the index value in the header of the ATM cell provided from the SAR transmission buffer 21 from the internal table, and reads the read VPI, VCI value of the ATM cell. After inserting into the header, it is provided to the cell transmission buffer 23. At this time, the uplink header converter 22 will erase the index value contained in the ATM cell.

The ATM cells stored in the cell transmit buffer 23 are provided to the cell bus matcher 24, and the cell bus matcher 24 is matched with the cell bus to sequentially order the ATM cells in the cell transmit buffer 23 to the cell bus. send.

The downlink header conversion circuit 30 includes a cell bus matching unit 31, and the cell bus matching unit 31 receives an ATM cell provided through the cell bus and provides it to the cell receiving buffer 32. The cell reception buffer 32 receives the ATM cells provided from the cell bus matching unit 31 and sequentially provides them to the downlink header converter 33. It will be readily apparent to those skilled in the art that the cell reception buffer 32 may be configured using a general first-in, first-out buffer.

The downlink header converting section 33 is for converting the header in the ATM cell provided from the cell receiving buffer 32. That is, the VPI and VCI values are set in the header of the ATM cell of the cell reception buffer 32, but an object of the present invention is to convert an ATM cell provided through the cell bus back into an E1 signal, and the corresponding E1 line. It is to provide to (L1-L8), and it cannot be implemented using VPI and VCI in ATM cell. To this end, the present invention constitutes a downlink header converter 33, and the downlink header converter 33 includes a table having the same contents as the uplink header converter 22. FIG. That is, in the table of the downlink header converter 33, index values corresponding to VPI and VCI values in the header of the ATM cell are stored, and the downlink header converter 33 indexes the VPI and VCI values of the ATM cell. The value is read from the table, the index value is inserted into the ATM cell header, and the VPI and VCI values in the header are erased.

The ATM cell from the downlink header conversion unit 33 is provided to the AAL1 SAR unit 13 via the SAR reception buffer 34, and the AAL1 SAR unit 13, as described above, is the ATM cell of the SAR reception buffer 34. Is changed to the E1 signal according to a non-structural scheme, and the changed E1 signal is provided to the E1 lines L1 to L8 corresponding to the index values included in the ATM cell.

On the other hand, as described above, when changing the E1 signals into ATM cells, the AAL1 SAR unit 13 forms an index corresponding to the E1 signal and inserts the index into the header of the ATM cell, and the uplink header converting unit 22 converts the header of the ATM cell. Insert the VPI and VCI values corresponding to my index into the ATM cell. Therefore, the index value of the AAL1 SAR unit 13 and the table value (VPI and VCI vs. index value) in the uplink header unit 22 must match each other, and this value is performed by the controller 40. That is, the control unit 40 is connected to the AAL1 SAR unit 13 and the uplink header converting unit 22, and a separate control device through the L bus or the like (it will be a device to control the transmission of the ATM cell as a whole.) The VPI, VCI values, and index values of the AAL1 SAR unit 13 and the uplink header converter 22 are set according to the control from the control unit.

Meanwhile, the downlink header conversion unit 33 and the AAL1 SAR unit 13 also perform a process of changing the VPI and VCI values in the header of the ATM cell to the index value, and the VPI, VCI value and the index value are also controlled by the controller 40. It will be readily appreciated that it should be determined by the control of.

On the other hand, the transmission rate of the E1 signal provided / supplied to / from the AAL1 SAR section 13 and the E1 matching sections 11 and 12 and the ATM cell provided / supplied to / from the SAR transmit / receive buffer 21/34. Since the transmission rates are different, it is necessary to synchronize them mutually in time. For this purpose, the SRTS unit 14 is configured, and the SRTS unit 14 provides a clock for the AAL1 SAR unit 13 to synchronize and convert the ATM cell and the E1 signal by mutual synchronization. On the other hand, since the E1 signals provided to the AAL1 SAR unit 13 are not always provided in phase phase, the difference between the reception clock of the E1 signal and the transmission clock of the ATM cell (the E1 signal is converted) must be known. Can be converted to an E1 signal. To this end, the AAL1 SAR unit 13 of the present invention inserts information (called an SRTS value) (allocating one byte) indicating the clock difference between the E1 signal and the ATM cell to insert the first payload of the ATM cell to convert the uplink header. And transmits to the circuit 20 and converts the ATM cell into an E1 signal according to the SRTS value included in the first payload of the ATM cell provided from the downlink header converting circuit 30 to the E1 matching unit 12. .

As described above, the apparatus of the present invention has an effect that the voice signal of the time division modulated channel unit can be easily recovered into the ATM cell, and the ATM cell can be easily restored to the time signal of the time division modulated channel unit.

Claims (6)

A device for interconverting a time division channel modulated signal and an asynchronous transfer mode ATM cell, A plurality of time division channel modulated signals are input, the time division channel modulated signals are sequentially transformed into ATM cells, and an index indicating the type of the time division channel modulated signal is inserted into a header of the ATM cell. An ATM Adaption Layer 1 Segmentation and Reassembly (SAR) unit for generating and transmitting time division channel modulated signals according to an index in a cell; An uplink header converting circuit for receiving an ATM cell from the AAL1 SAR unit, replacing an index in the ATM cell with a corresponding VPI, VCI, and including it in a header of the ATM cell and transmitting the same to a cell bus; And a downlink header conversion circuit that receives an ATM cell from the cell bus and replaces VPI and VCI in the ATM cell with a corresponding index and transmits it to the AAL1 SAR. The method of claim 1, wherein the uplink header conversion circuit, A SAR transmission buffer for receiving and sequentially transmitting ATM cells from the AAL1 SAR unit; An uplink header converting unit having a table having VPI and VCI values corresponding to the indexes, and replacing an index of an ATM cell provided from the SAR transmission buffer with the VPIs and VCIs; And a cell transmission buffer configured to sequentially transmit the ATM cells of the uplink header conversion unit. The method of claim 1, wherein the downlink header conversion circuit, A cell receiving buffer for receiving the ATM cell from the cell bus and transmitting the ATM cell sequentially; A downlink header converting unit including a table having an index corresponding to the VPI and the VCI, wherein the downlink header converting unit replaces the VPI and VCI of the ATM cell provided from the cell reception buffer with a corresponding index; And a SAR reception buffer for sequentially providing the ATM cells of the downlink header converter to the AAL1 SAR unit. The method of claim 3, wherein And a control unit which provides an index of the AAL 1 SAR unit and the uplink and downlink header units, and a VPI and a VCI in correspondence with each other. The method of claim 4, wherein And an SRTS unit for providing the clock to the AAL1 SAR unit for transmitting the ATM cell and the time division channel modulated signal by the AAL1 SAR. The method of claim 5, The AAL1 SAR inserts and transmits an SRTS value indicating a clock difference between an ATM cell and a time division channel modulated signal in a payload section of the ATM cell, and synchronizes with the SRTS value of a payload section in the received ATM cell. And asynchronous transmission mode cell interconversion device, characterized in that the cell is configured to recover a time division channel modulated signal.