KR20010011312A - Apparatus for controlling units and multiplexing cells in ADSL system - Google Patents

Abstract

PURPOSE: A control multiplexing device of an asymmetrical digital subscriber line(ADSL) is provided to connect with an asynchronous transfer mode(ATM) network and a multiplexed trunk signal data(STM)-1 or to a DS3, and to connect with other units with cell buses, and so transmitting ADSL up data to the ATM network, after the device disassembles down data received from the ATM network into cells so as to examine a user parameter control(UPC) to check an error, it transmits the UPC to an ADSL subscriber side through the cell buses. CONSTITUTION: A network interface(220) connects with an asynchronous transfer mode(ATM) network and a DS3 or to a multiplexed trunk signal data(STM)-1 level. An operation and maintenance(OAM)/user parameter control(UPC) processor(230) checks user parameters of ATM cells received from the network interface(220) to process OAM cells, and applies a loop-back process to the OAM cells to output the OAM cells through cell buses, then performs a reverse process. A signal processor(240) performs a signalling process to an ATM adaptation layer(AAL)5, and connects the ATM cells to the cell buses. A local area network(LAN) interface(250) interfaces with a LAN for a network management. An OAM interface(260) interfaces with a management console. A control processor(210) performs a predetermined sequence to control each block, and communicates with an upper management system.

Description

Apparatus for controlling units and multiplexing cells in ADSL system}

The present invention relates to an asymmetric digital subscriber network system (ADSL), and more particularly, to an ADSL control multiplexing device for multiplexing digital subscribers to connect to an ATM network and controlling the overall operation of the system.

In recent years, new communication services such as video-on-demand (VOD), home shopping, distance education, and high-speed web have emerged, and technology for connecting digital subscribers to the network at high speed is required. In other words, in the video business commonly referred to as VOD service, a subscriber network for connecting high speed video signals from the VOD server to the subscriber set-top box (STB) is required. When using an optical cable, broadband signals can be transmitted. However, ADSL technology using existing telephone lines has been widely studied because of the enormous cost added to construct a new optical line.

Asymmetrical Digital Subscriber Line (ADSL) system focuses on the asymmetrical traffic between network and subscribers, and the downlink channel transmitted from the network to the subscriber allocates a wide band for high speed transmission. It is a technology that efficiently uses the capacity of transmission line by allocating narrow bandwidth to the uplink channel.

In case of implementing such an asymmetric digital subscriber network system, a device for multiplexing and matching digital subscribers with an ATM network and controlling and managing the entire system is required.

Accordingly, an object of the present invention is to provide a control multiplexing device in an asymmetric digital subscriber network system.

In order to achieve the above object, an apparatus of the present invention is an asymmetric digital subscriber network system for providing a high-speed data service by connecting an information terminal to an ATM network with different traffic between an uplink channel and a downlink channel through a subscriber's telephone line. Network matching unit for connecting to the ATM network and DS3 or STM-1 level; Operation and maintenance / user parameter control (OAM / UPC) that inspects user parameters of ATM cells received from the network matching unit, processes OAM cells, processes loopbacks, outputs through cell buses, and performs the reverse process. Processing unit; A signal processing unit for performing signal processing in the AAL5 layer and connecting ATM cells to the cell bus; LAN matching unit for matching with the LAN for network management; Operation management matching unit for matching with the management console; And a control processing unit which controls each unit by performing a predetermined sequence and communicates with an upper management system.

1 is a block diagram illustrating an improved ADSL system to which the present invention may be applied;

2 is a detailed block diagram of a control multiplexing apparatus according to the present invention;

3 is a diagram illustrating a format of an OAM cell applied to the present invention;

4 is a diagram illustrating a format of a performance monitoring cell applied to the present invention;

5 is a diagram illustrating a format of a loopback cell applied to the present invention.

* Explanation of symbols for main parts of the drawings

102: ATM network 110: DSLAM

111: control multiplexing unit 112: cell bus extension

113: 1st expansion unit 114a, 114b: 2nd expansion unit

115a to 115d: ADSL subscriber registration unit 106a to 106d, 121a to 121d: splitter

120a ~ 120d: Home system 123a ~ 123d: ATU-R

125a-125d: PC 104: PSTN Network

210: control processing unit 220: network matching unit

230: OAM / UPC processing unit 240: signal processing unit

250: LAN matching unit 260: operation management matching unit

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an overall configuration diagram of an improved asymmetric digital subscriber network system to which the present invention can be applied, which includes a DSLM (DSLM) 110 installed in a telephone company (CO) and an indoor system installed in a subscriber's home ( 120). The DSLAM 110 includes a control multiplexing unit (CAMA) 111, a first expansion unit (AX1A: 113), a second expansion unit (AX2A: 114a and 114b), an ADSL subscriber matching unit (ASIA: 115a to 115d), and a splitter. It consists of 106a-106d. Here, the first expansion units EX1A: 113 and the second expansion units EX2A: 114a and 114b are self-expansion units 112 and are used to expand the self for accommodating ADSL subscribers.

The indoor system 120a to 120d includes a splitter 121a to 121d, an indoor ADSL transceiver (ATU-R: 123a to 123d), a personal computer (PC: 125a to 125d), and a general telephone line through a single telephone line. POTS is connected to a public telephone network (PSTN: 104), and computers (PCs 125a to 125d) can be simultaneously connected to an ATM network.

The ADSL system is a device for providing a high speed digital transmission function using a two-wire subscriber line installed between a subscriber and a telephone company. However, since the telephone subscriber line used is operated for the Plain Old Telephone Service (POTS), the ADSL transmission signal should be divided in the frequency band so as not to affect the telephony signal at all. That is, since the voice area used in the existing telephone is 4KHz or less, after allocating a high frequency band as a band for data communication, the voice signal and the data signal do not overlap each other by using a modulation technique of DMT or CAP.

In Fig. 1, ADSL subscriber matching units (ASIA) 115a to 115d are ADSL transceivers in a telephone station, and ASL-ADSL Transceiver Unit-Remote terminal end (123a to 123n) is an ADSL transceiver at a subscriber side. The splitters 106a to 106d and 121a to 121d are high-pass filters for blocking voice (POTS) signals and separate voice signals and data signals. In addition, the data signal has a full-duplex communication function, but has an asymmetric structure in which the amount of communication in the downward direction is larger than that in the upper direction. For example, the transmission rate of the uplink channel from the subscriber to the network is 16 to 640 Kbps, while the transmission rate of the downlink channel transmitted from the network to the subscriber is 1.5 to 9 Mbps.

G.dmt (G.992.1) and G.lite (G.992.2) have been proposed as ITU-T's ADSL standards applicable to these ADSL transceivers. The transmission speed is 640Kbps, and it is a high speed standard using 256 waves of DMT. G.lite is a simple standard with a maximum reception speed of 1.5Mbps and a maximum transmission speed of 512Kbps. In particular, G.lite makes installation easy by omitting the home splitter. And one ADSL line is connected to ADSL modem of telephone line end to provide high speed downstream channel, medium duplex channel, POST channel, etc. POTS channel is separated from digital modem by splitter to provide existing telephone service. The downstream channel has 1.5 ~ 8Mbps and the duplex channel has 16Kbps ~ 1Mbps. The ADSL transmission method is Amati's Discrete Multi Tone (DMT) and GlobeSpan's carrierless AM / PM (CAP) method. The CAP method is a single carrier method based on the QAM method, and the DMT method divides data into 249 carriers. It is a multicarrier system to send.

DMT is a multi-carrier method using multiple carriers. N / 2 carriers have a uniform bandwidth and are arranged at regular intervals of W Hz. Each carrier acts as an independent subchannel. It is a principle that modulation and detection of the QAM modulation method are performed by the distributed data. First, b-bit data input during T time is distributed to N / 2 subchannels. At this time, the amount of data allocated to each subchannel is not uniform, and the amount is determined according to the transmission quality index of the corresponding channel. Data allocated to each subchannel is mapped to one QAM symbol value having a complex value according to the QAM modulation scheme. If the QAM symbol value in the k-th subchannel is Xk, each symbol value represents the size and phase of the carrier as a pager of the corresponding QAM transmission signal, which is a frequency component of the ADSL transmission signal at the carrier frequency position. do. A symbol block composed of QAM symbols from each subchannel is transformed into a sample sequence in the time domain through an inverse transform (IFFT) in advance, and this pulse sequence is sequentially transmitted to a transmission path through a transmission filter. The power spectrum of the transmitted signal is uniformly distributed in the designated frequency band by making the average transmission power of the active subchannels all have the same value. This is accomplished by making the square mean values of all Xk equal when placing signal points in QAM modulation. The reception process is the reverse process of the transmission process. The received signals sampled (yi, i = 0 to N) during T time are obtained through the Fourier transform (FFT) to obtain {Yk, k = 0 to N / 2}. This output indicates the representation of the received signal in the frequency domain, which is a block of received QAM symbol values. By determining the corresponding symbol value for each subchannel, the original b-bit data content can be obtained. The entire signal transmitted during T time is called a DMT symbol by dividing it from the QAM symbols of each subchannel. Interference between DMT symbols occurs due to signal distortion of the transmission path during transmission. In order to solve this problem, a real system uses a method of inserting a prefix composed of P QAM symbols in front of the DMT symbol.

In Figure 1, the control multiplexing unit 113 of the present invention is connected to an ATM network and DS3 or STM-1 (155.52M) to form an ATM cell into an STM-1 frame or the reverse process and self-expansion unit 112 Is connected via Cellbus. The self-expansion unit 112 is a first expansion unit 113 directly connected to the control multiplexing unit 111 by Cellbus, and second expansion units 114a and 114b connected to the first expansion unit 113 by DS3. A plurality of ADSL subscriber matching units 115a to 115d are connected to the second expansion units 114a and 114b. In actual implementation, the control multiplexing unit (CAMA: 111) and the plurality of first expansion units (EX1A: 113) are mounted on the same shelf, and one first expansion unit (EX1A: 113) has two ports. And two second expansion units EX2A: 114a and 114b mounted on different shelves respectively. The EX2As 114a and 114b are mounted for each shelf one by one, and connect a plurality of ADSL subscriber matching units (ASIA: 115a to 115d) mounted on the same shelf.

On the other hand, the control multiplexing unit (CAMA) of the present invention, as shown in Figure 2, the control processing unit 210, network matching unit 220, operation and maintenance / user parameter control (OAM / UPC) processing unit 230, Signal processing unit 240, LAN matching unit 250, operation management matching unit 260 consists of a control function including the general management function of the system and receiving the STM-1 signal or DS3 signal from the ATM switching network to reduce the overhead After processing, it extracts the ATM cell and sends it to the subscriber matching unit and vice versa.

Referring to FIG. 2, the control processor 210 may include a CPU 211, a DRAM 212, an EPROM 213, a flash RAM 214, an NVRAM 215, a state and control register 216, and an EX1A control bus ( 217, the network matching unit 220 includes a DS3 driver 221, a DS3 matching unit 222, an optical module 223, and an STM-1 matching unit 224, and the OAM / UPC processing unit 230. An ATM layer processing unit 231 and a cell bus matching unit 232 are configured. The signal processor 240 includes an AAL5 hierarchical processor 241 and a cell bus matching unit 242, and the LAN matching unit 250 includes an Ethernet control unit 251 and an Ethernet transceiver 242. Here "OAM / UPC" stands for Operation And Maintenance / User Parameter Control.

In the control processing unit 210, the CPU 211 controls the overall operation after mounting the operating system (O.S), grasps all the state of the system and reports to the upper management system through the LAN (LAN). In the memory block, EPROM 213 stores data for initial booting, flash memory 214 stores control programs and various application programs, and DRAM 212 stores CPU 211 and other devices to store data. Can be. The NVRAM 215 is a space for storing data for the overall operational maintenance of the system. The NVRAM 215 is useful for backup of the system without losing data even when the power is turned off. The status and control register 216 has a status register for checking other unit dismounting and mounting status and other related information in the self, and has LED information so as to know the status of the unit itself. The EX1A control bus 217 provides a bus for controlling the first expansion unit 113.

The operation management matching unit 260 communicates with the operation terminal (console) through a 9-pin connector located at the front of the unit as an RS232C port, and inputs commands and outputs system status regarding overall maintenance of the system through the RS232C port. Has the function.

The LAN matching unit 250 is composed of an Ethernet control unit 251, an Ethernet transceiver 252, and a filter to provide a 10BaseT Ethernet interface for operation management of SNMP-based communication, and an RJ45 connector on the front of the unit. It is connected to LAN.

The optical module 223 in the network matching unit 220 converts the optical signal received through the optical path into an electrical signal, and converts the electrical signal into an optical signal and outputs the optical signal to the ATM network through the optical path. The STM-1 matching unit 224 receives the STM-1 frame input through the optical module 223, processes the control signal and the overhead in the STM-1 frame, extracts the ATM cell, and then transfers the error through the utopia interface. The cell is transferred to the AM / UPC processor 230. On the contrary, the cell is received from the OAM / UPC processor 230 to frame the ATM cell into an STM-1 frame, which is transmitted to the optical module 223. The physical layer of the STM-1 matching unit 224 extracts the bit string and the clock from the STM-1 pulse signal received from the line, and conversely pulses the bit string to be transmitted. The SVC-1 frame is found from the received bit string to extract VC-4, and the STM-1 frame is generated to map the payload. The boundary of the ATM cell is found from the received STM-1 frame to extract the cell, and the idle cell is discarded. In addition, by inserting an idle cell (idle cell) appropriately between the cells to be sent out to match the speed of the cell to the STM-1 payload speed, and checks the header error (HEC).

The DS3 matching unit 222 is a portion directly connected to the DS3-class line signal through the DS3 driver 221. The DS3 matching unit 222 extracts an ATM cell from a B3ZS coded PCLP multiframe structure and transmits the ATM cell to the OAM / UPC processing unit 230 through a utopia interface. Send ATM cell. Conversely, the ATM cell is received from the OAM / UPC processor 230, mapped to the PLCP frame, coded into B3ZS, and transmitted to the DS3 line. That is, the bit string is extracted from the 44.736 Mbps pulse signal received from the line, and the DS3 payload is extracted from the received bit string by finding the C-bit application multiframe synchronization. The PLCP frame synchronization is found from the received DS3 payload to extract the cell, and the idle cell is discarded. On the contrary, in the transmission process, an idle cell is appropriately inserted between cells to be transmitted so that the cell speed satisfies the speed of the PLCP payload, and then a cell is mapped to form a PLCP frame. Subsequently, a C-bit application multiframe is generated, and the bit string to be transmitted is converted into a pulse signal of 44.736 Mbps and output to the line.

The OAM / UPC processing unit 231 is in charge of the traffic polishing function to guarantee the quality (QoS) for the UBR / CBR service for the data transmitted from the network matching unit 220 and the cell bus matching unit 232, and ATM layer It is in charge of OAM function to perform fault and performance management in. At this time, the OAM function monitors failures and performances in the network and operates ATM and physical layers to divert the cell to another path or switch to a spare channel when an abnormality occurs. Important OAM functions in the embodiment of the present invention are shown in Table 1 below.

OAM function main function AIS Indicates a fault condition in the forward direction RDI Indicates a remote fault in the backward direction Continuity test Monitor cell continuity Loopback Provides connectivity monitoring and various test paths Forward performance monitoring Predict Forward Performance Reverse performance monitoring Predict the performance of the reverse Activation Deactivation Control performance monitoring and continuity check System management Only used in end systems

In Table 1, the OAM function in the ATM layer is performed for the point-to-point or segment of the VPC (VCC), and the "F4" information flow is bidirectional. OAM cells for the F4 information flow have the same VPI value as the VPC user cell and are distinguished by one or more pre-assigned VCI values.

As shown in FIG. 3, the format of the OAM cell is a 5-octet header, a 4-bit OAM type, a 4-bit function type, and a 45-octet function-specific field. It consists of a specific field, a 6-bit reserved area, and a 6-bit EDC (CRC-10) area, and the function of each cell according to the 4-bit OAM type and function type is Table 2 below.

OAM Type Coding Function type Coding Fault management One AIS 0 Fault management One RDI One Fault management One Continuity Check 100 Fault management One Loopback 1000 Performance Management 10 Forward monitoring 0 Performance Management 10 Backward reporting One Activation / Deactivation 1000 Performance Monitoring 0 Activation / Deactivation 1000 Continuity Check One System management 1111 - -

Referring to Table 2, it can be seen that "00010000" represents an AIS cell in fault management, and "00010100" is a continuity check cell. And "00100000" represents a forward monitoring cell for performance management, "00100001" represents a backward reporting cell, and "10000001" represents a continuity cell of activation / deactivation.

As shown in Fig. 4, the format of the performance monitoring cell is 8 bits of "MCSN", 16 bits of "TUC-0 + 1", 16 bits of "BEDC-0 + 1", and 16 bits of "TUC-. 0 ", 32 bits" TSTP ", 29 octets of unused area, 16 bits" TRCC-0 ", 8 bits" BLER-0 + 1 ", 16 bits" TRCC-0 + 1 " It consists of an area.

A continuity check (CC) is sent down by an endpoint or segment when no user cell is sent for a period of time and there is no VPC (VCC) failure. If the VPC (VCC) endpoint does not receive any cells for a predetermined time interval, it sends a VP (VC) -RDI to the far end.

As shown in FIG. 5, the loopback cell has a loopback indication field of 1 octet, a correlation tag of 4 octets, a loopback location ID of 16 octets, and a 16 octet It consists of a Loopback Source ID of and an octet of 8 octets of unused fields. A loopback indication of one octet consists of a 7 bit unused region and a 1 bit 0/1 region. The loopback function of the ATM layer is inserted at one location on the VPC / VCC and returned to another location without service interruption.

User Parameter Control (UPC) refers to the actions that the network takes on the UNI to monitor traffic based on the traffic network and the routing validity. The purpose of these actions is to protect network resources from intentional or unintentional misbehavior that could affect the QoS of other existing connections by monitoring for violations of negotiated variables and taking appropriate action. Traffic monitoring is performed for all connections across the UNI, and UPC applies to both user VPC / VCC. UPC is applied to all received cells except cells to be terminated in CAMA. At this time, the sanctioning method and the traffic descriptor are instructed by the NMS when the connection is established. Conformance determination applies the continuous-state Ricky Bucket algorithm of ITU-T I.371. Apply one or more Ricky buckets for every connection.

The cell bus matching units 232 and 242 perform VPI / VCI conversion in the ATM layer, and each unit transmits and receives data and transmits and transmits the IPC through the cell bus. Each unit is connected by one cell bus. Inlet and outlets support a UTOPIA interface, and the first cell bus matching unit 232 transmits and receives data cells from the ATM layer processing unit 231 and the second cell bus matching unit ( 242 transmits and receives signaling, IPC, ILMI cell. The AAL5 layer processing unit 241 recombines the ATM cells received from the cell bus matching unit 242, cuts the packet into ATM cells, and transmits the packet to the cell bus matching unit 242.

As described above, the control multiplexing device according to the present invention is connected to the ATM network by STM-1 or DS3 and connected to other units by cellbus to transfer ADSL uplink data to the ATM network, and received from the ATM network. After the downlink data is decomposed into cells, the user parameter (UPC) can be inspected and errors can be checked and transmitted to the ADSL subscriber through Cellbus.

Claims (3)

In the asymmetric digital subscriber network system for providing a high-speed data service by connecting the information terminal to the ATM network with different traffic between the uplink channel and the downlink channel through the subscriber's telephone line, A network matching unit for accessing an ATM network at a DS3 or STM-1 level; An OAM / UPC processing unit for inspecting user parameters of ATM cells received from the network matching unit according to a control signal, processing an OAM cell, processing a loopback, outputting a cell bus, and performing the reverse process; A signal processing unit for performing signal processing in the AAL5 layer and connecting ATM cells to the cell bus; LAN matching unit for matching with the LAN for network management; Operation management matching unit for matching with the management console; And By performing a predetermined sequence to process the input and output of the console through the operation management matching unit, to control the OAM / UPC processing unit, and transmits and receives the data of the signal processing unit and the AAL5 layer and the upper management system through the LAN matching unit A control multiplexing device for an asymmetric digital subscriber network system including a control processor for communicating. 2. The asymmetric digital subscriber network as claimed in claim 1, wherein the network matching unit comprises a DS3 matching unit for matching the ATM network with the DS3 level, and an STM-1 matching unit for matching the ATM network with the STM-1 level. Control Multiplexing System. The ATM layer processing unit of claim 1, wherein the OAM / UPC processing unit is matched with the STM-1 matching unit and a utopia interface to transmit and receive ATM cells, analyze and monitor headers of the cells, and the ATM layer processing unit and the utopia interface. An apparatus for controlling multiplexing of an asymmetric digital subscriber network system, comprising: a cell bus matching unit connected to provide cell routing paths and to match cell buses.