KR100382145B1 - Narrow-Band Service System for ATM-PON - Google Patents

Abstract

The present invention relates to a matching device for narrowband services in a low-cost optical subscriber transmitter having an ATM-based PON structure, and a narrowband service system including the matching device, wherein the matching device is dependent on an OLT and has a DS1E matching structure. Interface with PSTN switch, interface with ATM switch through B-ISDN matching device, digital conversion of DS1E signal transmitted from PSTN switch and conversion into E1 frame and reverse process function DS1E line mating portion; A TSI unit for allocating a time slot constituting an E1 signal transmitted from the DS1E line matching unit to a provisioned subscriber channel and a reverse process function thereof according to a command of a V5 processor; An ATM inter-working unit configured to reconstruct an E1 data transmitted from the TSI unit into an ATM signal and to perform a reverse process function thereof for transferring the upper level ATM layer; An S / UNI unit for transmitting an ATM signal transmitted from the ATM inter-working unit to a B-ISDN matching device and performing a reverse process function thereto; A V5 processor for performing a call processing function, a timeslot position reconfiguration control function, a V5 message processing function, an N-ISDN D-channel information processing function, and a signaling processing function; And a V5 processor matching unit performing a V5 message transfer function, an N-ISDN D-channel information transfer function, and a CAS transfer function, which has the effect of miniaturizing the ONU at a low cost and widening the OLT main system. If the system is configured as a service-only system and the narrowband service matching device is configured as necessary, and connected to the broadband service matching device in a broadband network matching structure, there is an effect of providing flexibility to the overall service.

Description

In the optical subscriber transmitter having the ATM-PON structure, the PSN matching device for narrowband service and the narrowband service system including the matching device {Narrow-Band Service System for ATM-PON}

The present invention relates to a system structure and a matching device for narrowband services in a low-cost optical subscriber transmitter having a passive optical network (PON) structure based on an Asynchronous Transfer Mode (ATM), and belongs to the optical subscriber transmission system.

Subscriber services that can be provided in the narrowband service system include Plain Old Telephone Service (POTS), Narrow-Band Integrated Services Digital Network (N-ISDN) service, E1 leased line service, and the like. (Public Switched Telephone Network) consists of matching device and narrowband subscriber service matching device.

The low-cost optical subscriber transmitter having the ATM-based PON structure includes an optical line termination (OLT) and an optical network unit (ONU). The PSTN matching device is a device dependent on the OLT and forms a DS1E matching structure with the PSTN exchanger, and an STM-1 optical matching structure with a Broad-Band Integrated Services Digital Network (B-ISDN) matching device in the OLT. The PSTN matching device is connected to the ATM switch of the OLT through the B-ISDN matching device.

The prior art is a PSTN matching device in demand dense optical subscriber transmitters. This device is installed in HDT (Host Digital Terminal) of demand dense optical subscriber transmitter to perform PSTN matching function.

High-density optical subscriber transmission system is a FTTC (Fiber To The Curb) service transmission platform consisting of HDT and ONU, which provides data related to service through optical lines from HDT to ONU in order to provide telephone and video services to subscribers. In the ONU, each subscriber transmits using the existing telephone line. HDT is installed in a telephone station, connects DS1E signal and ATM-based broadband signal delivered from broadband switching network, integrates and multiplexes into synchronous digital hierarchy, and performs optical transmission function and optical function for optical signal transmission to ONU, a power station. ONU is installed in distribution centers in dense residential areas such as apartment complexes to separate subscribers from optical signals transmitted from HDTs according to service and provide the subscribers with the reverse function.

The HDT receives four STM-1 (Synchronous Transfer Module-1) signals from the ATM switch, processes the overhead contained in the STM-1 signal, extracts the ATM cell, and sends it to the corresponding DTRU. Two ATRUs, a cell bus that is a transmission path for ATM cells, eight optical transceivers for connection between HDT and ONU, and a PSTN matching device that receives DS1E signals from PSTN and processes ATM cells and sends them to the OTRU through the cell bus And the like.

The ONU performs the function of separating each subscriber signal from the STM-4 optical signal transmitted from the HDT according to the service and providing the subscriber with the reverse function, and the EMS (Element Management System) is the operator terminal (TMN) as the operator terminal. It is a device that performs functions such as failure, charging, configuration, performance and security management according to the method.

The PSTN matching device in the demand-density optical subscriber transmission device is UTOPIA (Universal Test Operations PHY Interface for ATM) by attaching an AAL1 header and an ATM header to a line connection part that connects to a PSTN to send and receive DS1E signals and data input from the line connection part. ATM cell processing unit performing the operation of transmitting to the outside using the level 1 method and analyzing the header of the received ATM cell to determine whether to accept the service, and sending the accepted ATM cell to the line connection unit; The routing header according to the VCI value is added to the header of the ATM cell and transmitted to the cell bus, or when the routing header value of the ATM cell on the ATM cell bus on the cell bus matches the cell bus address value, it is accepted and outputted. Cell bus connector for outputting through the pin, ATM cells from the ATM cell processor are multiplexed to the cell bus connector A multiplexing / demultiplexing unit that demultiplexes the cells that are transmitting or sending from the cell bus interface and sends them to the ATM cell processor, which detects when the cell bus interface is ready to send the cell and routes the cells to the appropriate ATM cell processor. Alternatively, the ATM cell processing unit includes an FPGA unit for transmitting the cell when the cell bus connection unit has a cell to be transmitted and the cell bus connection unit is ready to receive the cell.

The demand dense optical subscriber transmission system is a system installed in a residential dense area such as an apartment, and a large-scale ONU is installed. This makes it an expensive device for installation in small subscriber areas.

The PON system architecture based on ATM is intended for relatively small subscriber units. This system is intended not only to install subscribers in small units and install the ONU as close as possible to the subscriber, but also to install the ONU in a small subscriber residential area which is unsuitable to install a large ONU such as the demand-dense optical subscriber transmission system. In this system, the ONU must not only be relatively small, but also low-cost.

SUMMARY OF THE INVENTION The present invention was derived to solve the problems of the conventional optical subscriber transmission system, and provides a system structure and a matching device for minimizing the ONU and efficiently utilizing a limited bandwidth in terms of providing a narrowband service. There is a purpose.

1 is a block diagram showing a system structure for a narrowband service in a low-cost optical subscriber transmitter having an ATM-based PON structure;

2 is a block diagram illustrating an ATM inter-working unit in detail in an ONU according to an embodiment of the present invention;

3 is a block diagram showing in detail the PSTN matching device according to an embodiment of the present invention.

According to a first aspect of the present invention, there is provided a PSTN matching device for narrowband service in a low-cost optical subscriber transmitter having an ATM-based PON structure, the matching device being dependent on the OLT, the PSTN through the DS1E matching structure. Interface with the switch, interface with the ATM switch through the B-ISDN matching device, digitally convert the DS1E signal transmitted from the PSTN switch to the E1 frame, and DS1E line matching to perform the reverse process function part; A TSI unit for allocating a time slot constituting an E1 signal transmitted from the DS1E line matching unit to a provisioned subscriber channel and a reverse process function thereof according to a command of a V5 processor; An ATM inter-working unit configured to reconstruct an E1 data transmitted from the TSI unit into an ATM signal and to perform a reverse process function thereof for transferring the upper level ATM layer; An S / UNI unit for transmitting an ATM signal transmitted from the ATM inter-working unit to a B-ISDN matching device and performing a reverse process function thereto; A V5 processor for performing a call processing function, a timeslot position reconfiguration control function, a V5 message processing function, an N-ISDN D-channel information processing function, and a signaling processing function; And a V5 processor matching unit performing a V5 message transfer function, an N-ISDN D-channel information transfer function, and a CAS (Channel Associated Signaling) transfer function.

According to a second aspect of the present invention, there is provided a system structure capable of implementing a narrowband service in an inexpensive optical subscriber transmitter having an ATM-based PON structure. The system structure is dependent on an OLT to provide a DS1E matching structure. Interface with the PSTN switch, interface with the ATM switch through the B-ISDN matching device where the ATM layer processing is performed, and digitally convert the DS1E signal transmitted from the PSTN switch into an E1 frame and a reverse process thereof. DS1E line matching unit to perform a function; A TSI unit for allocating a time slot constituting an E1 signal transmitted from the DS1E line matching unit to a provisioned subscriber channel and a reverse process function thereof according to a command of a V5 processor; An ATM inter-working unit configured to reconstruct an E1 data transmitted from the TSI unit into an ATM signal and to perform a reverse process function thereof for transferring the upper level ATM layer; An S / UNI unit for transmitting an ATM signal transmitted from the ATM inter-working unit to a B-ISDN matching device and performing a reverse process function thereto; A V5 processor for performing a call processing function, a timeslot position reconfiguration control function, a V5 message processing function, an N-ISDN D-channel information processing function, and a signaling processing function; And an OLT including a PSTN matching device for a narrowband service including a V5 processor matching unit performing a V5 message transfer function, an N-ISDN D-channel information transfer function, and a CAS transfer function; And

Subscriber matching device that performs matching function for POTS, N-ISDN and E1 leased line service, and function to reconstruct ATM signal to transfer E1 signal to upper ATM layer connected to the narrowband subscriber matching device and reverse process It is characterized by consisting of an ONU including an ATM Inter-Working unit performing a function.

1 is a system architecture diagram for a narrowband service in a low-cost optical subscriber transmitter having an ATM-based PON structure according to the present invention.

The DS1E line matching unit digitally converts the DS1E signal transmitted from the PSTN exchanger to the TSI unit as digital data, and transmits the digitally converted data as a standardized E1 signal and performs a reverse function thereof. Line code selection function, received signal loss detection function, Alarm Indication Signal (AIS) transmission function for received signal loss, line code violation detection function, Loop-Back function for DSIE signal, line fault monitoring function, DS1E frame alignment It performs functions such as accumulating information on frame synchronization errors and line code violations, detecting and generating remote frame alarms, and detecting and generating AIS and TS16AIS.

The time slot interchange unit (TSI) is a time slot position reconfiguration function for transferring each time slot constituting the E1 signal to a corresponding subscriber of each ONU, and a reverse process thereof, and control information between the PSTN switch and the V5 processor. V5 message extraction and insertion for exchanging data, N-ISDN D-channel information extraction and insertion for exchanging control information between V5 processors and N-ISDN subscriber matching devices in ONU, congestion tones and howling Performs the Howling Tone function.

The V5 processor performs a call processing function, a time slot position reconfiguration control function, a V5 message processing function, an N-ISDN D-channel information processing function, a signaling processing function, and the like.

The V5 processor matcher consists of a High-Level Data Link Control (HDLC) device and an FPGA and performs V5 message delivery, N-ISDN D-channel information delivery, and Channel Associated Signaling (CAS) delivery.

In addition, the ATM inter-working unit in OLT reconstructs the data reconstructed by the TSI unit into an E1 multi-frame or an E1 signal having a CAS, a function corresponding to the reverse process, and extracts CAS information. Insertion function, inserting idle pattern into inactive time slot to support Dynamic Bandwidth Circuit Emulation Service (DBCES), frame sync error information accumulation function, AIS detection and generation function, E1 signal AAL1 Segmentation And Reassembly (SAR) function, which provides DBCES as a function to reconstruct the ATM signal to the upper ATM layer and its reverse process, and timing recovery by the Synchronous Residual Time Stamp (SRTS). Recovery) function, UTOPIA interface function, ATM cell MUX / DEMUX function, etc.,

The S / UNI (Saturn User Network Interface) part transmits the ATM signal transmitted from the ATM Inter-Working part to the B-ISDN matching device and the reverse process thereof. The UTOPIA interface function, STM-1 It performs framing function and reverse function, scramble function and reverse function, AIS transmission and detection function, performance monitoring function, 155.52Mbps serial interface function, and recovering clock from received serial signal.

In ONU, the ATM Inter-Working unit reconstructs the data transmitted from the narrowband service subscriber matching device into an E1 multiframe or E1 signal having CAS, and a reverse function thereof, and forwards the E1 signal to a higher ATM layer. The AAL1 SAR function, which provides DBCES as a function corresponding to the reversal of ATM signals and the reverse process thereof, performs timing recovery by SRTS, and UTOPIA interface function.

The narrowband service subscriber matching device performs subscriber matching for POTS, N-ISDN, E1 leased line services, and the like.

The above-mentioned system can be used to securely allocate a narrowband service subscriber channel to the ONU, to place a V5 processor in the OLT, to utilize the DBCES function, and to process the ATM layer for the narrowband service in the OLT. Characterized in that performed through.

The fixed allocation of narrowband service subscriber channels to the ONU is one way to make the ONU small and inexpensive, because the ATM-based PON system architecture targets relatively small subscriber units. Narrowband services for fixed allocation of subscriber channels include POTS and N-ISDN services and do not include E1 leased line services. The present invention is a method of fixedly assigning subscriber channels to limit the number of subscribers of POTS and N-ISDN services to accommodate POTS and N-ISDN services in one E1, and to appropriately distribute time slots to POTS and N-ISDN services. I suggest assigning each one. In this case, three time slots should be allocated per subscriber for N-ISDN service and one time slot should be allocated per subscriber for POTS. An advantage of the method of fixedly allocating the narrowband service subscriber channel is that there is no need to have a TSI section in the ONU and thus no V5 processor. Considering that ATM-based PON system structure targets relatively small subscriber units and many ONUs are installed, fixed allocation of the narrowband service subscriber channel is appropriate for making an optical subscriber device low cost. have.

2 illustrates an ATM Inter-Working unit in detail in an ONU according to an embodiment of the present invention based on the above-mentioned method of fixedly allocating a narrowband service subscriber channel.

FPGA receives and sorts E1 data from POTS and N-ISDN subscriber matching devices and outputs E1 data on a bus where POTS subscriber matching devices and N-ISDN matching devices are commonly tied together. A function of supplying a clock and frame pulse to a narrowband service subscriber matching device, an E1 data alignment function, an E1 data output function, and a signaling generation function are performed.

The E1 framer receives the E1 data and signaling generated by the FPGA, generates an E1 multi-frame with CAS, and separates them again to provide E1 data and CAS to the AAL1 SAR device. As a function, the idle pattern is inserted into an inactive time slot, frame synchronization error information accumulation function, AIS detection and generation function, etc., to support DBCES.

The AAL1 SAR device performs an AAL1 SAR function that provides DBCES, a timing recovery function by SRTS, a UTOPIA interface function, and the like.

Placing the V5 processor in the OLT is a result of the fixed assignment of the narrowband service subscriber channel mentioned above. Since the ONU does not perform the TSI function, data corresponding to the POTS and N-ISDN services are allocated to a fixed time slot, bundled into one E1 signal, and converted into an ATM signal through the AAL1 SAR function and transmitted to the OLT transparently.

These signals from each ONU are converted into E1 signals through the AAL1 SAR function of the ATM Inter-Working part in the PSTN matching device. The V5 processor will not be involved until this process proceeds. In this way, the subscriber signals in the transmitted E1 signals can be delivered only through a subscriber channel established through negotiation between the PSTN exchange and the V5 processor. In this process, the TSI function and the intervention of the V5 processor are required.

Leveraging the DBCES feature is an efficient use of limited resources. Due to the nature of ATM-PON, bottle-neck may occur for upstream data. Since each ONU has one E1 allocated for narrowband service, the resource that should be allocated to the narrowband service becomes 131.072Mbps in the 64-Q ATM-PON system. This result, of course, corresponds to the case where the AAL1 CES (Circuit Emulation Service) is performed in E1 units.

It is not uncommon for all subscribers to require narrowband services for each ONU when the system is in operation. That is, on average, the proportion of the E1 band used as a narrowband service for each ONU is not very high. Therefore, the AAL1 CES of the conventional concept cannot effectively utilize resources. The "ATM Forum's DBCES Specification (AF-VTOA-0085)" shows a CES method for efficiently utilizing limited resources, which can solve the above problems.

DBCES allocates service resources flexibly according to whether or not they occur, and detects whether each time slot constituting the E1 signal is activated and reflects this in the process of creating an ATM cell. The main thing is not to.

The ATM layer processing for narrowband services is performed through the B-ISDN matching device to reduce the complexity of configuring the system and to provide flexibility for the overall service. This is because the number of narrowband service subscribers is very flexible compared to the number of broadband service subscribers and the lighting is becoming less important.

Connecting the narrowband service matcher with the broadband service matcher to the upper layer of the ATM should always allocate certain bands for narrowband services, regardless of the high or low demand for narrowband services, thereby reducing the liquidity of the overall service. do. Therefore, if the main system of the OLT is configured as a system for broadband service only and a narrowband service matching device is configured as necessary, the OLT main system is connected to the broadband service matching device in a broadband network matching structure, thereby providing flexibility to the overall service.

In addition, the complexity of the system is reduced compared to the case where the narrowband service matching device is configured with the broadband service matching device, and above all, the OLT volume can be reduced.

3 illustrates a PSTN matching device in detail according to an embodiment of the present invention based on the functions included in the above-described system structure and FIG. 1.

The DS1E matching unit is designed to accommodate up to 16E1 in consideration of V5.2. The DS1E matching unit independently converts each DS1E signal transmitted from the PSTN switch and converts it into an E1 frame, and performs the reverse process. Line code selection function, reception signal loss detection function, AIS transmission function for reception signal loss, line code violation detection function, Loop-Back function for DSIE signal, line failure monitoring function, DS1E frame alignment function, frame synchronization error And it accumulates information on line code violation, remote frame alarm detection and generation function, AIS and TS16AIS detection and generation function.

TSI part is designed considering PON up to 64 quarters, and separates E1 signal transmitted from DSSTE matching part from PSTN switch by subscriber channel unit and transfers it to EON signal up to 64 ONUs according to command of V5 processor. It is a function of allocating slots and vice versa. It is divided into four functional blocks, first of which is a V5 message extraction function for extracting control information transmitted from a PSTN exchange to a V5 processor. The first is the function of allocating time slots per subscriber channel according to the pre-command of the V5 processor in the ONU direction from the PSTN exchange, and the insertion of congestion tone, howling tone, and N-ISDN D-channel information. Ability to extract N-ISDN D-channel information from up to 64 E1 signals from ONU; fourth, V5 Pro from ONU to PSTN exchange According to the pre-command of the stand is performed such V5 message inserting function for inserting the control information to be transmitted to the PSTN exchange from the function processor and V5 for allocating time slots to the subscriber unit channel.

The V5 processor performs a call processing function, a time slot position reconfiguration control function, a V5 message processing function, an N-ISDN D-channel information processing function, a signaling processing function, and the like.

The V5 processor matching unit is composed of an HDLC device and an FPGA, and transmits the V5 message extracted from the TSI to the V5 processor and the V5 message generated from the V5 processor through the LAPV5 controller, which is an HDLC device, to the TSI. Function to transfer N-ISDN D-channel information extracted from TSI unit to V5 processor through LAPD controller, which is a device, and to transfer N-ISDN D-channel information generated from V5 processor to TSI unit, through PSTN FPGA Ability to transfer CAS extracted from E1 framer in ATM Inter-Working section to V5 processor and N-ISDN D via ISDN FPGA to deliver CAS generated in V5 processor to E1 framer in ATM Inter-Working section Extracting information for DLC (Digital Loop Carrier) mode from the channel information and delivering it to the V5 processor, and information combining N-ISDN D-channel information and information for DLC mode generated from the V5 processor, It transmits congestion tone and howling tone to TSI.

The ATM Inter-Working unit is composed of an E1 framer and an AAL1 DBCES device.The E1 framer combines the E1 unit data delivered separately from each ONU in the TSI unit and the CAS delivered from the V5 processor to create an E1 multi-frame with CAS. And generating the E1 signal and signaling again in order to deliver it to the AAL1 DBCES device, and combining the E1 signal and the signaling delivered from the AAL1DBCES device to generate an E1 multi-frame having a CAS, and transmitting the E1 unit data to the TSI unit. Ability to generate E1 unit data and CAS to deliver CAS to the V5 processor, AAL1 SAR capability to provide DBCES via AAL1 DBCES device, and multiplex ATM signals delivered from AAL1 DBCES device via ATM cell MUX Demultiplexing to deliver ATM cells delivered from S / UNI to AAL1 DBCES device through ATM cell DEMUX To perform CAS information extraction and insertion, insert idle patterns into inactive time slots to support DBCES, frame sync error information accumulation, AIS detection and generation, AAL1 SAR functionality to provide DBCES, and SRTS Timing recovery function, UTOPIA interface function, ATM cell MUX / DEMUX function.

The S / UNI unit performs the function of transmitting ATM signals transmitted from the ATM Inter-Working unit to the B-ISDN matching device and the reverse process thereof. The UTOPIA interface function, the STM-1 framing function, It performs the function corresponding to the reverse process for the reverse process, the scramble function and the reverse function for the reverse process, the AIS transmission and detection function, the performance monitoring function, the 155.52Mbps serial interface function, and the function of restoring the clock from the received serial signal. .

As described above, the present invention has the following effects.

First, when the ONU is designed by applying a method of fixedly allocating a narrowband service subscriber channel to the ONU with the V5 processor in the OLT according to the system structure according to the present invention, it may be a compact and low-cost optical subscriber device.

By utilizing the DBCES function mentioned in the system structure according to the present invention, the disadvantages of the ATM-PON system can be compensated for, thereby efficiently utilizing system resources.

According to the system structure according to the present invention, if the OLT main system is configured as a system for broadband service only and a narrowband service matching device is configured as necessary, the OLT main system is connected to the broadband service matching device in a broadband network matching structure to provide fluidity to the overall service. can do.

Claims (5)

Subordinate to OLT, interface with PSTN exchange through DS1E matching structure, interface with ATM switch through B-ISDN matching, A DS1E line matching unit for digitally converting the DS1E signal transmitted from the PSTN exchanger and converting the DS1E signal into an E1 frame and performing a reverse process thereto; A TSI unit for allocating a time slot constituting an E1 signal transmitted from the DS1E line matching unit to a provisioned subscriber channel and a reverse process function thereof according to a command of a V5 processor; An ATM inter-working unit configured to reconstruct an E1 data transmitted from the TSI unit into an ATM signal and to perform a reverse process function thereof for transferring the upper level ATM layer; An S / UNI unit for transmitting an ATM signal transmitted from the ATM inter-working unit to a B-ISDN matching device and performing a reverse process function thereto; A V5 processor for performing a call processing function, a timeslot position reconfiguration control function, a V5 message processing function, an N-ISDN D-channel information processing function, and a signaling processing function; And And a V5 processor matching unit for performing a V5 message transfer function, an N-ISDN D-channel information transfer function, and a CAS transfer function. A DS1E line matching unit for digitally converting the DS1E signal transmitted from the PSTN exchanger and converting the DS1E signal into an E1 frame and performing a reverse process thereto; A TSI unit performing a function of allocating a time slot constituting an E1 signal transmitted from the DS1E line matching unit to a provisioned Gaiser channel and a reverse process function according to a command of a V5 processor; An ATM inter-working unit configured to reconstruct an E1 data transmitted from the TSI unit into an ATM signal and to perform a reverse process function thereof for transferring the upper level ATM layer; An S / UNI unit for transmitting an ATM signal transmitted from the ATM inter-working unit to a B-ISDN matching device and performing a reverse process function thereto; A V5 processor for performing a call processing function, a timeslot position reconfiguration control function, a V5 message processing function, an N-ISDN D-channel information processing function, and a signaling processing function; And a V5 processor matching unit configured to perform a V5 message transfer function, an N-ISDN D-channel information transfer function, and a CAS transfer function. An OLT interfaced with a PSTN switch through the DS1E matching structure, connected to a B-ISDN matching device that performs ATM layer processing, and broadband network matching to interface with an ATM switch; And Subscriber matching device that performs matching function for POTS, N-ISDN and E1 leased line service, and function to reconstruct ATM signal to transfer E1 signal to upper ATM layer connected to the narrowband subscriber matching device and the reverse A transmission system capable of implementing a narrowband service in an ATM-PON low-cost optical subscriber transmitter comprising an ONU including an ATM inter-working unit performing a process function. The method of claim 2, The OLT main system is configured as a system for broadband service only, and the PSTN matching device can be selectively configured. The method of claim 2 or 3, And a narrowband service subscriber channel of the ONU's ATM Inter-Working unit is fixedly allocated. The method of claim 4, wherein And the ATM inter-working unit of the PSTN matching device and the ONU uses AAL1 DBCES.