KR0147760B1 - Synchronous optical transmission system - Google Patents

Abstract

The present invention relates to a synchronous optical transmission system. In particular, up to 84 DS1, 63 DS1E, and 3 DS3 digital dependent signals among digital interface signals are synchronously multiplexed to STM-1 using the synchronous multiplexing scheme of 1TU-T G.703. And a synchronous optical transmission system capable of time slot exchange and branch combining for optical transmission by demultiplexing.

The synchronous optical transmission system of the present invention includes a main control unit for controlling all units of the system, and a North American first digital signal service unit for multiplexing or demultiplexing up to four asynchronous North American series first digital signals into subordinate unit group signals. A first European digital signal service unit for multiplexing or demultiplexing up to three asynchronous European first digital signals into a dependent unit group signal, and transferring the first digital signal service unit to a spare unit; An adjunct which receives a subordinate unit group signal from the North American series first digital signal service unit and the European series first digital signal service unit, and multiplexes into an adaptive unit signal or performs demultiplexing thereof. Negative unit multiplexing unit and one asynchronous third digital signal Up to three admittances from the third digital signal service unit, which receives and multiplexes into an ad hoc adaptive unit signal, or performs multiplexing thereof, and the multiplexing unit and the third digital signal service unit multiplexing unit; An optical transmission / reception unit for receiving and transmitting a multiplexing unit signal to a synchronous transport module signal and performing an optical transmission / reception function, the admitting unit multiplexing unit, a third digital signal service unit, and an optical transmission / reception unit; A timeslot exchange unit connected to perform timeslot exchange for the eleventh, twelfth, and third virtual container signals, and a data communication unit that transmits system status information and control commands to the power station for remote maintenance of the power system; Clock supply for clock signals for synchronous multiplexing and control A synchronous optical transmission system characterized by including a class unit.

Description

Synchronous Optical Transmission System

1 is a block diagram of a synchronous optical transmission system according to an embodiment of the present invention.

2 is a multiplex structure diagram according to an embodiment of the present invention.

3 is a front mounting diagram of the synchronous optical transmission system shown in FIG.

Figure 4a is a point-to-point network configuration according to an embodiment of the present invention.

4b is a linear network diagram according to an embodiment of the present invention.

Figure 4c is an annular network configuration according to an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

10: Main control unit (MCU)

11: North American first digital signal service unit (DS1)

12: European First Digital Signal Service Unit (DS1E)

13: Adjustable unit multiplexing unit (AUMX)

14: 3rd digital signal service unit (DS3)

15: Optical Transceiver Unit (OTRU) 16: Time Slot Exchange Unit (TSI)

17: Data communication unit (DCU) 18: Clock supply unit (CLK)

19: switching unit (SW)

101: Preliminary North American First Digital Signal Service Unit (DS1)

102: Preliminary European First Digital Signal Service Unit (DS1E)

The present invention relates to a synchronous optical transmission system, and in particular, up to 84 DS1 (1.544 Mbps), 63 DS1E (2.048 Mbps), and 3 DS3 (44.736 Mbps) digital dependent signals of digital interface signals are included in ITU-T G.703. Synchronous multiplexing with Synchronous Transport Module-1 (STM-1) using the synchronous multiplexing method to perform optical transmission, performing this reverse function, and time slot exchange and branch combining for DS1, DS1E, and DS3 signals. This relates to a possible synchronous optical transmission system.

Generally, there are synchronous multiplexing and asynchronous multiplexing methods for multiplexing and transmitting digital dependent signals. Currently, asynchronous transmission method and synchronous transmission are planned to be switched from the existing asynchronous method to a synchronous method that is easy to operate and maintain. It is expected that the method will exist for some time. Also, in the synchronous multiplexing function, since the digital dependent signal is not completely synchronized, only the STM-1 frame has a synchronous structure, and the asynchronous dependent signal uses asynchronous mapping by bit stuffing.

In the conventional synchronous optical transmission device, the North American first level digital signal (Digital Signal level 1, hereinafter referred to as DS1), the European first level digital signal (Digital Signal level 1 European, hereinafter referred to as DS1E), and the North American STM-1 performs synchronous multiplexing and demultiplexing with respect to the dependent signal of the third level digital signal (hereinafter referred to as DS3) and performs optical transmission and reception.

However, only the multiplexing ACL DUR multiplexing and optical transmission of the STM-1 signal by the synchronous multiplexing method for the dependent signals of DS1, DS1E, and DS3 are impossible. There is a limitation in the use of the transmission device because it can not be configured, there is a difficulty in economical network configuration.

Accordingly, an object of the present invention is to solve the above problems, and an object thereof is to change a transmission path of a dependent signal without changing a wiring, and to perform branch combining on a dependent signal and to configure a linear and annular network. It is to provide an optical transmission system for performing the.

In order to achieve the above object, the present invention provides a main control unit for controlling all units of the system, and a first North American series digital multiplexing of up to four asynchronous North American series first digital signals to subordinate unit group signals or the reverse multiplexing. A signal service unit, a European first digital signal service unit for multiplexing or demultiplexing up to three asynchronous European first digital signals into a dependent unit group signal, and a first digital signal service unit; A slave unit group signal from a switching unit configured to switch over to the first digital signal service unit and the first digital signal service unit in North America, and a first digital signal service unit in Europe, and multiplexed into an adaptive unit signal or demultiplexed thereto Adaptative unit multiplexing unit and one asynchronous third unit A third digital signal service unit for receiving a de-signal and multiplexing or demultiplexing an ad- ministtive unit signal, and up to three signals from the ad- ministive unit and the third digital signal service unit multiplexing unit; An optical transmission / reception unit for receiving an adaptive unit signal, multiplexing or demultiplexing into a synchronous transport module signal, and performing an optical transmission / reception function, the adaptive unit multiplexing unit, a third digital signal service unit, and an optical; A time slot exchange unit connected to the transmit / receive unit to perform timeslot exchange for the 11th, 12th and 3rd virtual container signals, and data for transmitting system status information and control commands to the power station for remote maintenance of the power system; Communication unit and a clock signal for synchronous multiplexing and controlling the system. A synchronous optical transmission system comprising a clock supply unit.

Hereinafter, the present invention will be described with reference to the accompanying drawings. 1 is a configuration diagram of a synchronous optical transmission system according to an embodiment of the present invention, and FIG. 2 is a multiplex structure diagram according to an embodiment of the present invention. In the synchronous optical transmission system according to the present invention, the main control unit 10 for controlling all units, and the DS1 multiplexing four asynchronous DS1s with a tributary unit group signal (hereinafter referred to as TUG2) or performing demultiplexing thereof. Receives the TUG2 from the service unit 11 and the DS1E service unit 12 which multiplexes or demultiplexes three asynchronous DS1Es to TUG2, and calls an administrative unit3 (hereinafter called AU3). ), An ADMX unit 13 for multiplexing or performing demultiplexing thereof, and one asynchronous DS3 and multiplexing with AU3 or demultiplexing thereof. Receives three AU3s from the performing DS3 service unit 14 and the AUMX unit 13 and the DS3 service unit 14 and multiplexes or demultiplexes the synchronous STM-1 to perform optical transmission and reception functions. An optical transmission and reception unit (hereinafter referred to as an OTRU) unit 15 and an AUMX unit 13, a DS3 service unit 14, and an OTRU unit 15 are connected to each other to form an eleventh virtual container signal (Virtual). Container 11 (hereinafter referred to as VC11), Time Slot Interchange (hereinafter referred to as TSI) unit 16, which performs timeslot exchange for VC12, VC3, and the state of the system for remote maintenance of the power system. Data communication unit (DCU, 17) for transmitting information and control instructions to a power station, and a clock supply unit (CLK) for supplying clock signals necessary for synchronous multiplexing and control of the system (18). ), A spare DS1 service unit 101 to be replaced in case of failure of the DS1 service unit 11, a spare DS1 E service unit 102 to be replaced in case of a failure of the DS1E service unit 12, and the DS1. Of the service unit 11 and the DS1E service unit 12 It is provided with a switching unit (SW) (hereinafter referred to as SW) if at least one failure occurs.

The operation of the present invention will be described in detail below.

The function of each unit of the optical transmission system of the present invention is as follows.

The MCU unit 10 functions as a fault monitoring and maintenance of all units mounted in the system. In the event of a failure of the MCU unit 10, all maintenance related functions including the switching of the unit and the line cannot be performed, but they do not affect service. On the front of the MCU unit 10, there are LEDs indicating an alarm state, a loopback state, an alarm generation, an audible alarm cutoff, and an alarm history state of the common part to display the state of the system.

The DS1 unit 11 receives four AMI or B8ZS bipolar 1.544Mbps DS1 signals, extracts clock and unipolar Non Return to Zero (NRZ) data, and performs mapping process to add bit stuffing and overhead. To generate TU11. These four TU11 signals are multiplexed into TUG2 signals and perform the reverse function. The MCU unit performs control functions related to maintenance and testing of a tributary unit (hereinafter referred to as a TU) overhead byte processing and an internal unit detection function. If the service of the DS1 unit 11 is not provided, the transfer is automatically made to the spare DS1 unit 101, and after the transfer, the failure unit is diagnosed. When the cause of the failure is resolved, the service is returned from the spare DS1 unit 101. .

The DS1E unit 12 receives three DS1E signals having a speed of 2.408 Mbps, extracts clock and unipolar NRZ data, and performs mapping to add stuffing bits and overhead to generate TU12. These three TU12 signals are multiplexed into TUG2 and perform their reverse function. The MCU unit 10 has control functions related to maintenance and testing of the TU overhead byte processing, unit internal defect detection function, and the like. The DS1E unit 12 has a self-service diagnostic function, and when an abnormality occurs, the DS1E unit 102 is automatically switched to the spare DS1E unit 102. After the transfer, the failure unit is diagnosed. Return to 102).

The AUMX unit 13 receives up to seven TUG2 signals from the DS1 unit 11 or the DS1E unit 12, multiplexing and pass overhead are inserted to form the VC3 signal, and the AU pointer is inserted to generate the AU3 signal. The AU3 signal is sent to the operational TSI unit 16 and the spare TSI unit 106. In addition, after receiving the AU3 signal from the TSI unit 16 and performing pointer analysis and overhead processing, it is demultiplexed into seven TUG2s and connected to the DS1 unit 11 or the DS1E unit 12.

The DS3 unit 14 connects the DS3 signal to perform equalization, clock extraction, pass-through insertion, and adding stuffing bits to form and reverse the AU3 signal through synchronous multiplexing. ).

The OTRU unit 15 receives three AU3 signals having a speed of 51.84 Mbps from the TSI unit 16 and synchronously multiplexes them with STM, converts them into optical signals, and then has optical transmission to the power station after scrambling and its reverse function. The TSI unit 16 connects to the DS3 unit 14, the AUMX unit 13, and the OTRU unit 15 and exchanges timeslots through pointer reordering of each signal for 84 VC11 or 63 VC12 or 3 VC3 signals. Function The timeslot exchange is performed by the command of the MCU unit 10. In addition, in the annular network, the signals from both OTRU units 15 are selected from the AIS or LOP detection of the VC11, VC12, and VC3 signals, and the bit error detection is performed to select a good quality signal.

The DCU unit 17 has a communication function between devices and operators, and information related to control and service provision of the system is passed to the MCU unit 10. The DCU unit 17 functions to deliver data in the form of messages relating to operation and maintenance delivered to the data communication channel in the overhead section of the SDH frame structure.

The CLK unit 18 has a function of providing a synchronous clock to each unit of the system, and provides three operation modes of external synchronization, internal synchronization, and loop synchronization. . In each mode, the multiplexed clock and control clock required by the system are generated and supplied to each unit by using a phase locked loop circuit (PLL) and a divider from the reference signal. In addition, the control of the MCU unit 10 allows selection of a reference clock and switching when a failure occurs.

The SW unit 19 has a function of switching the service by connecting an input / output signal to the spare DS1 unit 101 or the spare DS1E unit 102 when the operating DS1 unit 11 or the DS1E unit 12 fails. do. The spare unit can be replaced at a ratio of up to 7: 1. The switching of the input / output signal by the drive of the SW unit 19 is performed, and the service is returned by the operation of the relay when the cause of the failure is removed. The control of the SW unit 19 for this reversible switching is made by the MCU unit 10.

The spare DS1 unit 101 or DS1E unit 102 is replaced in case of failure of the DS1 unit 11 or the DS1E unit 12, respectively.

The spare AUMX unit 103, the spare DS3 unit 104, the spare OTRU unit 105, and the spare CLK unit 108 are each an AUMX unit 13, a DS3 unit 14, and an OTRU unit 15. ) Can be replaced in case of failure of the CLK unit 18.

3 is a front mounting diagram of the synchronous optical transmission system shown in FIG.

Since the DS1 unit 11 and the DS1E unit 12 are multiplexed with the same TUG2 signal, they can be mounted at the same position. The DS3 unit 14 and the AUMX unit 13 can be mounted at the same position because they are multiplexed with the same AU3 signal.

For the linear network configuration, the OTRU unit 15 is mounted at a portion where the DS3 unit 14 and the AUMX unit 13 can be mounted.

On the other hand, in the annular network configuration, the OTRU unit 15 is mounted only on the left side of the TSI unit 16, and there is no unit switching function.

4 is a network diagram according to an embodiment of the present invention, FIG. 4a is a point-to-point network diagram, 4b is a linear network diagram, and 4c is an annular network diagram.

In the point-to-point configuration, the branch coupling optical transmission systems 41 and 42 correspond to one-to-one. In this configuration, the dependent signals of DS1, DS1E, DS3 can change the transmission path without changing the physical wiring by changing the time slot using a command.

In the linear network configuration, a plurality of optical transmission systems 43, 44, and 45 are arranged in a linear manner. In the middle optical transmission system 44 of the network, the time slot exchange function enables the branched coupling of the desired DS1, DS1E, and DS3. Do. The transmission rate of the transmitted signal is limited to 155.520 Mbps of STM-1.

In the annular network, closed loops are formed in which the optical transmission systems 46, 47, 48, and 49 bite back and forth. Time slot exchange function is available in transmission system of each stage, and transmission speed is STM-1. Only two OTRU units on the left side of the TSI unit are used, and these two OTRU units transmit the same signal in different directions, and when receiving, the optical signals from two different directions are received by two OTRU units and synchronously demultiplexed to allow TSI. The signal performance of VC11, VC12, and VC3 in the unit is evaluated so that a good quality signal is selected. These signal selection criteria are prioritized in order of AIS or LOP detection of VC11, VC12, and VC3, and excessive bit error detection so that a signal of good quality is selected. This is called a two-fiber unidirectional pass switching annular network.

According to the above, the present invention synchronously multiplexes and demultiplexes dependent signals such as DS1, DS1E, DS3, etc. into STM-1 signals, and is equipped with a TSI unit having a timeslot switching function to transmit the physical signals without physical relocation of the dependent signals in each transmission node. It is possible to change the path, branch-combination of subordinate signals is possible, and various transmission network configurations such as point-to-point, linear, and ring are possible. In addition, performance monitoring of each unit mounted can be detected and 1 + 1 and up to 7: 1 unit switching is possible to increase the availability, and mixed mounting of DS1, DS1E units, DS3 units, AUMX units, and OTRU units Mixed mounting is possible and various services are efficiently performed without wasting unit mounting space.

Claims (14)

A main control unit that controls all units of the system, a North American first digital signal service unit that multiplexes or demultiplexes up to four asynchronous North American first digital signals into a subordinate group group signal, and up to three asynchronous A first European digital signal service unit for multiplexing or demultiplexing a European first digital signal into a subordinate unit group signal, a switching unit for switching the first digital signal service unit to a spare unit, and the North America An adaptive unit multiplexing unit which receives the dependent unit group signal from the series first digital signal service unit and the European first digital signal service unit, and multiplexes or demultiplexes it into an adaptive unit signal; Receives an asynchronous third digital signal Receive a maximum of three admitted unit signals from the third digital signal service unit multiplexing or demultiplexing the signal, and from the adaptive unit and the third digital signal service unit multiplexing unit. An optical transmission / reception unit for multiplexing or demultiplexing with a synchronous transport module signal and performing an optical transmission / reception function, and an 11th, 12th, and 12th connected to the adaptive unit multiplexing unit, a third digital signal service unit, and an optical transmission / reception unit; 3 A time slot exchange unit that performs timeslot exchange for virtual container signals, a data communication unit that transmits system status information and control commands to the power station for remote maintenance of the power system, and synchronous multiplexing and control of the system. And a clock supply unit for supplying a clock signal required for Synchronous optical transmission system. 2. The method of claim 1, wherein the asynchronous North American first digital signal is a North American level first digital signal having a transmission rate of 1.544 Mbps, and the Asynchronous European First digital signal has a European rate of 2.048 Mbps. And a first-level digital signal level, and the third asynchronous digital signal is a North American-type third level digital signal having a transmission rate of 44.736 Mbps. The STM-1 synchronous transport system according to claim 1, wherein the optical transmission system transmits up to 84 North American asynchronous first digital signals, up to 63 asynchronous European first digital signals, and up to three asynchronous third digital signals. A synchronous optical transmission system comprising multiplexing or demultiplexing into module signals. 2. The synchronous optical transmission system according to claim 1, wherein the 11th, 12th and 3rd virtual container signals are time-slot exchanged and branched functions are performed on the DS1, DS1E, and DS3 signals. The synchronous optical transmission system according to claim 1, wherein the North American first digital signal service unit and the European first digital signal service unit are mounted at the same location. The synchronous optical transmission system according to claim 1, wherein the adaptive unit multiplexing unit and the third digital signal service unit are mounted at the same location. The synchronous optical transmission system according to claim 1, wherein the optical transmission / reception unit is mounted at a position where any one of the adjuster tip unit multiplexing unit and the third digital signal service unit is mounted to form a linear network. The synchronous optical transmission system according to claim 1, wherein the optical transmission / reception unit is mounted on the left side of the timeslot exchange unit for the annular network configuration. The synchronous optical transmission system according to claim 1, wherein the North American first digital signal service unit performs synchronous multiplexing of up to four first digital signals into subunit group signals and performs demultiplexing thereof. And said first European digital signal service unit performs synchronous multiplexing of up to three first digital signals into subunit group signals and performs demultiplexing thereof. The first digital signal service unit of claim 1, wherein the first North American digital signal service unit and the European first digital signal service unit are configured in three layers so as to have one band for each layer, and the first North American digital signal service unit in each layer. And a European first digital signal service unit can be mixedly accommodated. The synchronous optical transmission system according to claim 1, wherein the clock supply unit provides a clock in an external synchronization, an internal synchronization, a loop synchronization, and a holdover mode. 2. The method of claim 1, wherein the North American first digital signal service unit and the European first digital signal service unit in the event of a unit failure in order to increase availability include: 7: 1; And a third digital signal service unit, a timeslot switching unit, an optical transmission / reception unit, and a clock supply unit are switched to 1 + 1. 2. The optical transmission and reception unit of claim 1, wherein the optical transmission / reception unit eliminates the 1 + 1 switching function and transmits the two optical transmission / reception unit traffics equally in both directions, and demultiplexes the signals received from the two optical transmission / reception units at the receiving end and exchanges the timeslots. And a two-fiber unidirectional path switching annular network for selecting one of the eleventh virtual container signal, the twelfth virtual container signal, and the third virtual container signal with high quality from the unit.