KR100242427B1 - A method for multiplexing video data and a taxi video service module using atm network - Google Patents

Abstract

The present invention relates to a video data service of an ATM network supporting on-demand video service.

A LIU for performing a function of receiving an MPEG2 video signal composed of 188 bytes from a subscriber side; An AAL 5 processor configured to configure an ATM cell by using the video signal received from the LIU or to extract a video signal by receiving an ATM cell; A local multiplexer for transmitting the ATM cell received from the AAL5 processor to the VMCA side through an ATM cell bus; And a processor unit for controlling the LIU, the AAL5 processing unit, and a local multiplexing unit, and a bus driving unit for carrying an ATM cell between the VMCA side and the local multiplexing unit.

In addition, the video signal multiplexing method according to the present invention,

A first step of receiving an MPEG-2 video stream from a subscriber side; A second step of checking the boundaries of the transmission bit strings received in the first step without discriminating them; It comprises a third step of configuring the cell in the form of AAL5.

Description

Taxi access video service device and video signal multiplexing method using asynchronous transmission mode network

The present invention relates to a transparent Asynchronous Transmitter-Receiver Interface (TAXI) using an asynchronous transmission mode network. The present invention relates to a connected video service device and a video signal multiplexing method. TAXI-connected video service using ATM network to increase economics by using half of the number of cable strands used in the prior art and to increase the processing speed by configuring ATM cells without checking MPEG frame boundaries in ATM multiplexer A device and a method for multiplexing a video signal.

1 is a block diagram of an MPEG video data service apparatus using a conventional RS-422.

As shown, an MPEG-2 encoder; It consists of ATM multiplexer.

In the case of using RS-422, since the clock signal and the data signal are provided separately, it has the advantage that information processing below a certain speed can be performed without defining a reference clock between network devices.

In case of using the conventional RS-422 interface configured as shown in FIG. 1, two cables for transmission, two cables for reception, two cables for clock signal, and two cables for checking the existence of data on the transmission path should be used.

In other words, when connecting an MPEG2 encoder and an ATM multiplexer, 8 cables are used for each subscriber. In this case, when the number of ports increases or the distance between devices is long, the configuration and management of the cable is difficult.

In addition, in the conventional ATM multiplexing device, since the ATM cell is configured after checking the boundary of the MPEG frame, the boundary of the frame is guaranteed, while the processing speed is slow and additional circuits are required.

The present invention has been made to solve the conventional problems as described above,

In case of supporting MPEG2 service through RS-422 interface by using TAXI of ATM network, it is possible to increase the economical efficiency by using two pairs of four strands of the number of strands of cable existing between MPEG2 encoder and ATM multiplexing equipment. The purpose of the present invention is to provide a video service apparatus and a video signal multiplexing method by constructing an ATM cell without checking the boundaries of MPEG frames to increase processing speed and using no additional circuit.

1 is a block diagram of a conventional MPEG 2 video service.

2 is a configuration diagram of a TAXI access video service device according to the present invention;

3 is a PDU configuration of a TAXI interface.

The present invention for achieving the above object,

A Line Interface Unit (hereinafter referred to as LIU) which functions to receive an MPEG2 video signal composed of 188 bytes from the subscriber side; An ATM Adaptation Layer type 5 (hereinafter referred to as AAL 5) processing unit for configuring an ATM cell using the video signal received from the LIU or performing a reverse process thereof; A local multiplexer for transmitting an ATM cell received from the AAL5 processor to a video multiplexer control assembly (hereinafter referred to as VMCA) through an ATM cell bus; A microprocessor unit for controlling the LIU, the AAL5 processing unit, and the local multiplexing unit, and a bus driver for transporting the ATM cell from the VMCA side to the local multiplexing unit from the VMCA side.

The present invention for achieving another object,

A first step of receiving an MPEG-2 video stream in the multiplexing device as described above; A second step of inspecting the boundary of the video stream received in the first step without discriminating it; And a third step of reducing the video multiplexing delay time in the multiplexing device by configuring the cell in AAL5 form.

2 shows an overall configuration diagram of a TAXI access video service apparatus using an ATM network according to the present invention.

As shown, a LIU having a function of receiving an MPEG2 video signal composed of 188 bytes from a subscriber side through an encoder; An AAL 5 processor configured to configure an ATM cell using the video signal received from the LIU or perform the reverse process; A local multiplexer for transmitting the ATM cell received from the AAL5 processor to the VMCA side through an ATM cell bus; The microprocessor unit is configured to control the LIU, the AAL5 processor, and the local multiplexer, and the bus driver is configured to carry an ATM cell between the VMCA side and the local multiplexer.

The LIU includes a TAXI receiver configured to receive an MPEG-2 frame composed of 188 bytes from an encoder on the subscriber side, a reframe control unit configured to perform rerambling of the frame, and the received data. First In First Out (hereinafter referred to as FIFO) buffer unit that performs a function of temporarily storing an ATM cell before processing.

An AAL5 segment unit for converting data stored in the FIFO into an AAL5 form and converting the data into an ATM cell; A FIFO buffer unit for storing ATM cells in order to multiplex the ATM cells produced by the above process; And a header storage unit for storing information on a virtual path identifier (VPI) / virtual channel identifier (VCI) in the ATM cell header.

The local multiplexer converts the MPEG-2 transmission bit streams received from four TAXIs into ATM cells for each port and inputs them to the FIFO in the AAL5 processor. A multiplexing unit for performing; It consists of a buffer unit that can check the status of various data processing units by extracting and storing a test pattern for a self-test function in a local multiplexer.

The micro processor unit and a processor; ROM; RAM; MFP; Inter-Processor Communication (hereinafter referred to as IPC) for communication with a decoder and VMCA.

The bus driver unit is configured as a local multiplexer as a driver for the interface between the IPC RAM and the cell bus.

Hereinafter, the operation of the TAXI access video service apparatus using the ATM network according to the present invention will be described in detail with reference to FIG.

The reference clock is set in the TAXI receiver of the encoder and the LIU, and it is possible to process information in the reference clock due to the characteristics of TAXI.

In fact, the TAXI device is clocked at 67.5 MHz, but since the actual data is input at a speed of 6 to 8 MHz, the LIU extracts the actual data and terminates the line.

After the MPEG-2 coded information, the information is stored in the FIFO buffer unit in the LIU unit and waits for AAL processing of valid data.

The AAL 5 processing unit sequentially reads two MPEG 2 frames received from the LIU and stored in the FIFO, connects 8-byte trailers, and connects 384 bytes of AAL5 Common Part Convergence Sublayer protocol data. It constitutes a unit (Protocol Data Unit: hereinafter referred to as PDU).

The 8-byte trailer has a 4-byte long part and common part type indicating function of 4 bytes and a length of CPCS PDU as a result of Cyclic Redundancy Check Code (CRC-32) operation for error checking of CPCS PDU. It consists of a Common Part Indicator (CPI) part and a CPCS-UU part of 1 byte.

The CPCS-PDU is referred to as AAL5 Segmentation And Reassembly having a length of 48 bytes (SAR). After segmentation into PDUs, the ATM cell header is attached to the 48-byte SAR-PDU. The ATM cell is configured.

3 is a diagram illustrating a process of generating an ATM cell by the above process.

As shown, a total of 384 bytes of CPCS_PDUs are shown, including two 188 byte transport bit streams and an 8 byte trailer.

The CPCS_PDU is divided into 48 bytes of SAR_PDUs and consists of eight ATM cells by adding an ATM cell header to each PDU.

The ATM cell header includes a virtual path identifier (VPI) and a virtual channel identifier (VCI) indicating a virtual path and a virtual channel through which an ATM cell is transmitted. The eight ATM cells configured as described above are AAL 5 processed in one packet unit.

The video information converted from the AAL5 processor to the ATM cell through the above process is stored in the FIFO in the AAL5 processor.

The local multiplexer multiplexes the ATM cells stored in the FIFO by Statistical Multilpexing, and delivers them to the bus driver. The process of loading the ATM cell on the bus driver is made at the request of VMCA.

Information for various operations administration and maintenance (OAM) is delivered to the upper processor using the IPC module. The transmission of the OAM information is to perform the IPC by polling (polling) operation by the request of the upper processor.

The TAXI access video service device using the ATM network as described above supports unidirectional video information flow due to the characteristics of the digital CATV system. Can be.

In addition, two TAXI boards are available for self-testing and interworking with other equipment.

As described above, the present invention,

Synchronous Transport Module level 1 (STM-1) for digital video signals from MPEG-2 encoders on digital CATV networks to support up to 20 T2-class interfaces while ensuring cable diversity and bandwidth diversity. By applying to a device that supports ATM networks by using express lines, video services are possible through commercially available access standards.

In addition, when using TAXI, one cable is used for transmission and only two cables are used for transmission and reception. Therefore, the number of required cables is reduced by half compared to the conventional RS-422 connection. Can be obtained.

Claims (7)

A LIU for performing a function of receiving an MPEG2 video signal composed of 188 bytes from a subscriber side; An AAL 5 processor configured to configure an ATM cell by using the video signal received from the LIU or to extract a video signal by receiving an ATM cell; A local multiplexer for transmitting the ATM cell received from the AAL5 processor to the VMCA side through an ATM cell bus; TAXI using an asynchronous transmission mode network comprising a processor unit for controlling the LIU, the AAL5 processing unit and the local multiplexing unit and a bus driving unit for carrying ATM cells between the VMCA side and the local multiplexing unit. Connection video service device. The method of claim 1, wherein the LIU, TAXI receiver for receiving MPEG-2 frame consisting of 188 bytes at subscriber side, A frame control unit for performing an actual frame reframe function; And a FIFO buffer unit for temporarily storing the received video data for ATM processing. The method of claim 1, wherein the AAL5 processing unit, An AAL5 segment unit configured to function as an ATM cell in the LIU; A FIFO buffer unit for storing an ATM cell for multiplexing the ATM cell created by the AAL5 segment unit; And a header storage unit configured to store information on a cell header in order to manufacture an ATM cell in the AAL5 segment unit. The method of claim 1, wherein the local multiplexer, A multiplexing unit for matching the ATM cells input to the FIFO in the AAL5 processing unit at a rate suitable for a cell bus; TAXI connection video using an asynchronous transmission mode network, comprising a buffer unit for checking a state of various data processing units by extracting and storing test cells for a self-test function in a local processor. Service device. The method of claim 1, A TAXI access video service device using an asynchronous transmission mode network, characterized in that two TAXIs are added by adding one TAXI port in the opposite direction to support a bidirectional digital CATV service. A first step of receiving an MPEG-2 video stream from a subscriber side; A second step of checking the boundaries of the transmission bit strings received in the first step without discriminating them; And a third step of configuring a cell in the form of AAL5. The method of claim 6, ATM transmission mode characterized by STM-1 class ATM transmission using up to T2 class 20 TAXI connections, and flexibly accommodating the subscriber's video signal by statistical multiplexing according to the change of subscriber's video data volume. A video signal multiplexing method in a TAXI access video service apparatus using a network.

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