KR20000015046A - Physical layer connector of adsl modem - Google Patents

Abstract

PURPOSE: A physical layer connector capable of simply connecting an ATM physical layer device by embodying an UTOPIA interface between an ATM25 block supporting a physical ATM 25.6 Mbps and a CDB in an ADSL modem is provided. CONSTITUTION: A physical layer connector of an asynchronous digital subscriber line modem, the connector comprising: a first inverter(23) for inverting an input clock and transmitting a receiving input clock of a cell delineation block and a transmitting/receiving clock of an asynchronous transfer mode; a D flip-flop(24) for receiving an output of the first inverter(23) as a clock, and receiving and delaying data of a transmission terminal cell for transmission of the ATM25; a second inverter(25) for the data of a transmission terminal cell for transmission of the ATM25 from the D flip-flop(24) to a receiving terminal read enable of the cell delineation block; a NAND circuit(26) for NANDing and transmitting the data of a transmission terminal cell for transmission of the ATM25 from the second inverter(25) and data of the D flip-flop(24) to a transmitting terminal read enable of the ATM25; a third inverter(27) for inverting the clock of the first inverter(23) and transmitting an input transmitting clock of the cell delineation block; a fourth inverter(28) for inverting and transmitting the data of a transmission terminal cell for transmission of the ATM25 to a transmitting terminal read enable of the cell delineation block; and a fifth inverter(29) for inverting and transmitting the data of a transmission terminal cell for transmission of the ATM25 to a receiving terminal read enable of the ATM25.

Description

Physical layer connection device of ADSL modem

The present invention relates to an asynchronous digital subscriber line (ADSL) modem, and in particular, an ATM25 block and a cell delineation block (CDB) supporting physical Asynchronous Transfer Mode (ATM) 25.6 Mbps in an ADSL modem. The present invention relates to an apparatus for easily connecting an ATM physical layer device by implementing a UTOPIA (Universal Test and Operations Physical Interface for ATM) interface.

Typically, ADSL systems use conventional telephone lines (twisted copper lines) to communicate (asymmetrically) 1.5Mbits / sec (or 6Mbits / sec) in the direction going down to the home and 16kbits / sec in the up direction. It is a technology that can be realized. Thus, the same telephone line can coexist with the existing telephone or the basic interface (2B + D) of the Integrated Services Digital Network (ISDN). The ADSL is used as an experimental service of "Video Dialtone", which is a video transmission service of a US local telephone recall.

1 is a block diagram of such a general ADSL system.

As shown here, ADSL Terminal Unit Central Office (ATU-C) of Digital Subscriber Line Asynchronous Modem (DSLAM), which is connected to ATM network 1, stores subscriber channel information and is equipped with a modem. Wow; POTS that separates data from public switched telephone network (PSTN) 3 and telephone 4 of telephone company and data through ATM network 1, and transmits data to subscriber 7 using copper wire Public Office Telephone System (Splitter) (5) (6); It consists of an ADSL Terminal Unit Central Office Receive Unit (ATU-R) 7 which is connected to the ATU-C (2) through the POTS separator (5) (6) to perform a connection with the subscriber equipment (8). do.

Thus, ADSL system transmits / receives bidirectional data through broadband public network (ATM) through ISP (International Signaling Point), server, and Internet. And ADSL system is controlled / managed by ADSL network management system to interface bi-directional data of broadband public network through ATM exchange. The POTS separator operates to separate the data of the PSTN and the telephone and the data through the ATM switching network by the public exchange, and transmit the data to the subscriber using the copper wire.

The ATM interface related to the ADSL modem in the ADSL system configured and operated as described above is a recent technology, and is related to the firmware implementation of the physical ATM25 interface in the conventional ATM network system.

In order to connect the ATM physical layer, an ATM handler block including a CDB function and an ATM25 interface of a physical layer must be connected to each other. The present invention has been presented to implement such a connection circuit.

Accordingly, the present invention has been proposed to solve the above-mentioned general problems, and an object of the present invention is to implement an ATM physical layer device by implementing a UTOPIA interface between an ATM25 block and a CDB supporting physical ATM 25.6Mbps in an ADSL modem. It is to provide a physical layer connection device of the ADSL modem that can be easily connected.

In order to achieve the above object, the physical layer connection device of the ADSL modem according to the present invention,

A first inverting device for inverting the input clock and transmitting the received clock to the receive input clock of the CDB and the transmit / receive clock of the ATM25; A D flip-flop that receives the output of the first inverting element as a clock and receives and delays data of a transmitting terminal full cell used to transmit the ATM25; A second inverting element for transmitting data of a transmitting terminal full cell used for transmitting the ATM25 to a receiving terminal lead enable of the CDB; A negative logical element which receives data of a complete cell of a receiving terminal used for transmission of the CDB and data of the D flip-flop, performs a negative logical multiplication, and transmits the negative logical product to a transmitting terminal read enable of the ATM25; A third inverting device for inverting the clock of the first inverting device and transmitting the inverted clock to the transmission input clock of the CDB; A fourth inverting element for inverting data of a receiving terminal full cell used for transmitting the ATM25 by inverting the transmitting terminal read enable of the CDB; The technical configuration is characterized by comprising a fifth inverting element which inverts data of a transmitting terminal full cell used for transmitting the CDB and transmits the data to the receiving terminal lead enable of the ATM25.

1 is a block diagram of a general ADSL system,

2 is a block diagram of an ADSL modem to which the present invention is applied;

3 is a block diagram of a physical layer connection device of the ADSL modem according to the present invention;

4 is a cell output timing diagram of the UTOPIA mode in FIG.

5 is a table showing values of the parameter of FIG.

6 is a cell input timing diagram of the UTOPIA mode in FIG.

FIG. 7 is a table showing values of the parameter of FIG. 6.

<Explanation of symbols for main parts of the drawings>

11: POTS distribution unit 12: hybrid conversion unit

13 line driver 14 analog converter

15: DMT modulation and demodulation unit 16: ADSL framer

17: CDB 18: ATM25

19: transceiver 20: NIC in PC

Hereinafter, with reference to the accompanying drawings an embodiment according to the technical idea of the physical layer connection device of the present invention ADSL modem as described in detail as follows.

First, the present invention is a system based on the Discrete Multitone Modulation (DMT) technology based on ATM in an ADSL system. The DMT technology has several advantages over the carrierless amplitude-modulation and phase-modulation (CAP) method. ATM-based ADSL is more expensive than Network Interface Card (NIC) than Ethernet-based ADSL, but can manage non-IP traffic or video without major protocol upgrades. It is also easy to connect multiple service providers to the same access network. However, the subscriber end may also consider supporting both ATM and Ethernet. Therefore, even in view of cost, ATM-based ADSL is unavoidable because Ethernet-based alone cannot be used. In order to connect the ATM physical layer, the ATM handler block including the CDB function and the ATM25 interface of the physical layer must be connected to each other. The UTOPIA interface implements logic for connecting the physical layers to support the system based on ATM. Do it.

Figure 2 is a block diagram of an ADSL modem to which the present invention is applied, and its operation is as follows.

First, reference numeral 11 denotes a POTS separation unit that separates data of a telephone station's PSTN and a telephone and data through an ATM network, and transmits data to a subscriber using a copper wire, and 12 denotes a hybrid conversion unit that performs line impedance matching. 13 is a line driver for amplifying an analog signal, which is an ADSL DMT signal, 14 is an analog converter which performs digital / analog filtering by performing digital conversion or analog conversion of an analog signal, and 15 is modulation and demodulation of a DMT. It is a DMT modulation and demodulation unit.

In addition, reference numeral 16 is an ADSL framer connected to a serial interface and CDB, 17 is a Cell Delineation Block (CDB) that performs Transmission Convergence (TC) of the physical layer, and 18 is a TC and Physical Medium Dependent (PMD). Physical middle slave) ATM25, 19 is a transceiver, and 20 is a NIC in a PC.

Here, the CDB 17 can be viewed as an ATM handler. The function of the CDB 17 is that of the BISDN (Broadband Integrated Services Digital Network) protocol reference model, which inserts or extracts an ATM cell on a line interface signal having a possible transmission format. It performs some functions of the transport convergence sublayer and ATM layer.

In particular, cell delineation is performed by generating or terminating an unsigned ATM cell of a specific format and performing cell payload scrambling / descramble.

In addition, the ATM cell interface supports a FIFO (First In First Out) interface and a UTOPIA interface in units of bytes, but uses the UTOPIA interface mode in units of bytes in the present invention.

At this time, the receiving terminal output is composed of 1-bit odd parity and 8 bits of data bit, and the transmitting terminal output is composed of only 8 bits of data bit.

In addition, the ATM 25Mbps interface block of ATM25 (18) implements the ATM Forum's physical layer standard for 25.6Mbps ATM Network communication. The physical layer is divided into a Physical Medium Dependent (PMD) sublayer and a TC sublayer. The PMD sublayer supports transmission media connections that match the Telecommunications Industries Association (TIA) / Electronic Industries Association (EIA) 568 (Unshield Twisted Pair (UTP) Category 3). Includes transmit, receive, and timing recovery functions. The TC sublayer is defined by line, coding, scrambling, data framing and synchronization functions.

3 is a block diagram of a physical layer connection device of an ADSL modem according to the present invention.

First, reference numeral 21 is a line for transmitting RTD [0: 7], which is a receiving terminal data output, from the cell output of the CDB 17 to TxDATA [0: 7], which is the transmission data of the ATM25 18, and 22, the CDB. A line for transmitting a Receive Terminal Start Of Cell (RxSOC), which is a cell start signal of a receiving terminal of (17), to a TxSOC, which is a cell start signal of a transmitting terminal of the ATM25 (18), and 23 is an inverted 3.2 MHz input CDB RICLK (Receive Input Clock), which is a receive input clock of (17), and a first inverting element which transmits to TxCLK and RxCLK, which are transmit / receive clocks of ATM25 (18), and 24 denotes an output of the first inverting element (24). A D flip-flop that receives a clock and transmits data of a TxCLAV (Transmit Terminal Complete Cell Available for Transfer), which is a transmission terminal complete cell used for transmission of the ATM25 (18), and 25 is used for transmission of the ATM25 (18). TxCLAV (Transmit Terminal Complete Cell Available for Transf) er) is a second inverting device for transmitting data to RxENB * (Receive Terminal Read Enable) which is a receiving terminal lead enable of the CDB 17, and 26 is a receiving terminal full cell used for transmitting the CDB 17. Transmit Terminal Read Enable (TxENB *), which is a transmit terminal read enable of the ATM25 (18) by performing a negative logic operation upon receiving data of RxCLAV (Receive Terminal Complete Cell Available for Transfer) and data of the D flip-flop 24 Is a third inverting device which inverts the clock of the first inverting device 23 and transmits it to the TICLK (Transmit Input Clock) which is the transmission input clock of the CDB 17.

Also, reference numeral 28 inverts and transmits data of Receive Terminal Complete Cell Available for Transfer (RxCLAV), which is a receiving terminal complete cell, used for transmission of the ATM25 (18) to TxENB *, which is a transmitting terminal lead enable of the CDB 17. A fourth inverting device, and 29 denotes inverting data of TxCLAV (Transmit Terminal Complete Cell Available for Transfer) which is a transmitting terminal complete cell used for transmitting the CDB 17, thereby enabling the receiving terminal lead of the ATM25 18. A fifth inverting device transmitting to RxENB *, 30 is a line for transmitting RxSOC data, which is a cell start signal of a receiving terminal of the ATM25 18, to TxSOC, which is a cell start signal of a transmitting terminal of the CDB, and 31 is an ATM25 RxDATA [0: 7], which is the reception data of (18), is transmitted to TTD [0: 7] (Transmit Terminal Data Out) which is the transmission terminal data output of the CDB 17, and 32 is the CDB 17. Phase with AD [0: 7] A line interconnecting the [70] of the address AD of the ATM25 (18).

4 is a cell output timing diagram of the UTOPIA mode in FIG. 3, FIG. 5 is a table showing values of the parameters of FIG. 4, FIG. 6 is a cell input timing diagram of the UTOPIA mode in FIG. 3, and FIG. This table shows the values of the parameters.

Here, TTD16 / TxSOC of FIG. 6 indicates the first valid byte, and TCF1 / TxCLAV is an indication capable of accepting cell transmission.

In addition, the direction and meaning of the reception interface signal in the UTOPIA mode are shown in Table 1 below.

signal direction meaning RxDATA PHY → ATM Data bus RxSOC PHY → ATM Start of cell RxENB ATM → PHY Enable data transfer RxEmpty / RxCLAV PHY → ATM FIFO Empty / cell available RxCLK ATM → PHY Transmit / Interface Octet Clock

In addition, the direction and meaning of the transmission interface signal in UTOPIA mode are shown in Table 2 below.

signal direction meaning RxDATA ATM → PHY Data bus RxSOC ATM → PHY Start of cell RxENB ATM → PHY Enable data transfer RxEmpty / RxCLAV PHY → ATM FIFO Empty / cell available RxCLK ATM → PHY Transmit / Interface Octet Clock

In this way, the present invention implements the UTOPIA interface between the ATM25 block and the CDB supporting the physical ATM 25.6Mbps in the ADSL modem to simply connect the ATM physical layer device.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments. Accordingly, the above description does not limit the scope of the invention as defined by the limitations of the following claims.

As described above, the physical layer connection device of the ADSL modem according to the present invention implements the UTOPIA interface between the ATM25 block and the CDB, thereby effectively connecting the ATM physical layer device.

Claims (1)

A first inverting device for inverting the input clock to transmit the received input clock of the CDB (Cell Delineation Block) and the transmitting / receiving clock of ATM (Asynchronous Transfer Mode) 25; A D flip-flop that receives the output of the first inverting element as a clock and receives and delays data of a transmitting terminal full cell used to transmit the ATM25; A second inverting element for transmitting data of a transmitting terminal full cell used for transmitting the ATM25 to a receiving terminal lead enable of the CDB; A negative logical element which receives data of a complete cell of a receiving terminal used for transmission of the CDB and data of the D flip-flop, performs a negative logical multiplication, and transmits the negative logical product to a transmitting terminal read enable of the ATM25; A third inverting device for inverting the clock of the first inverting device and transmitting the inverted clock to the transmission input clock of the CDB; A fourth inverting element for inverting data of a receiving terminal full cell used for transmitting the ATM25 by inverting the transmitting terminal read enable of the CDB; A physical layer connection device of an Asynchronous Digital Subscriber Line (ADSL) modem, comprising: a fifth inverting element for inverting data of a transmitting terminal full cell used for transmitting the CDB and transmitting the data to a receiving terminal lead enable of the ATM25; .