KR910009670B1 - Apparatus for multiplexing subscribers lines of digital switching network - Google Patents

Abstract

The multiplexing apparatus provides the ISDN 2B + D class service to the ISDN subscriber in remote sides. The apparatus comprises a subscriber transmission line unit (1) having multiple U interface channel units (U < U) for dividing or inserting c-channel and for terminating the U interface transmission lines, a system synchronizing and multiplexing unit (2) for synchronizing the received data to system timing signal, and for inserting and extracting the B-channel and the c-channel from time slots, a trunk interface unit (4) for executing the DS1 class data communication, a common control unit (3) for processing the maintenance data related to the unit (1) and the basic accessing and for executing the DS1 class alarming information communication between the trunk interface unit (4), and a maintenance unit (5) for inserting the maintenance information into the time slot of DS1 class frame.

Description

Medium ISDN Subscriber Multidevice

1 is a block diagram showing a configuration of the present invention.

2 is a U-interface multiframe structure diagram.

3 is a North American V6 interface frame configuration.

4 is a European V6 interface frame configuration.

5 is an exemplary diagram showing a case where the present invention is directly connected to an ISDN exchange.

6 is an exemplary diagram when the present invention operates in the COT-RT mode.

7 is a block diagram showing a configuration of a trunk interface unit of the present invention.

8 is a block diagram showing the configuration of the CPU of the present invention.

FIG. 9 illustrates one embodiment of a partial configuration of a U interface channel unit when the present invention is used as a COT. FIG.

FIG. 10 illustrates one embodiment of a partial configuration of a U interface channel unit when the present invention is used in RT.

11A is a frame format diagram on a U interface line.

11b is a timing relationship diagram between a system clock and a 2.048 Mbps data stream.

* Explanation of symbols for the main parts of the drawings

1: subscriber line transmission unit 2: system synchronization and multiple unit

3: common control unit 4: trunk interface unit

5: Maintenance department

The present invention relates to a medium scale ISDN subscriber multiple device (hereinafter simply referred to as PMUX).

Every country is devoted to the early establishment of a comprehensive information and communication network (hereinafter referred to as ISDN), which is based on the basic concept of integrating and implementing various services through a standardized interface at home. Doing. Until now, the development of communication networks has been focused on the digital exchange and interstation transmission. However, the digitalization of the subscriber network has become an urgent problem for ISDN construction, and it would be a very desirable method in terms of economic and technical aspects to apply the techniques already acquired in the inter-station transmission field to the subscriber network.

The present invention is an ISDN switch by multiplying 10 or 12 ISDN basic access subscribers scattered in groups in remote areas by applying already established inter-station transmission technology to subscriber network at a bit rate of DS1 (Digital Signal Level 1: 1.544Mbps). It aims to provide efficient and economical ISDN service using existing DSI transmission facilities to subscribers in the area where ISDN exchange is not installed, especially at the beginning of ISDN introduction.

In order to achieve the above object, the present invention provides a subscriber multi-device for providing ISDN 2B + D-class services to a plurality of ISDN basic access subscribers distributed remotely, and terminates a plurality of U interface lines. And a subscriber line transmission means having a plurality of U-interface channel units (UCUs) for separating or inserting the C-channel, and the data received from the subscriber line transmission means in synchronization with the system timing and transmitted from each subscriber. System synchronization and multiple means having a plurality of synchronization circuit units (SNUs) for inserting or extracting channel and D channel data into a preset time slot, the system synchronization and multiple means and a trunk interface unit ( Trunk in to transmit / receive DS1 level signal with TIU) It is provided with a face means and a central processing unit (CPU) to exchange maintenance information related to basic access with the subscriber line transmission means, to exchange DS1 level alarm information and time slot information with the trunk interface means, and to provide maintenance. Maintenance means having common control means for providing information and maintenance unit (MTU) for receiving basic access (BA) related maintenance information from the common control means and inserting or extracting it into a specific time slot of a DS1 class frame. Consists of. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of the present invention, where 1 is a subscriber line transmission unit, 2 is a system synchronization and multiplexing unit, 3 is a common control unit, 4 is a trunk interface unit, and 5 is a maintenance unit.

The present invention is composed of a system synchronization and multiple unit 2, a maintenance unit 5, a common control unit 3, and a trunk interface unit 4 as shown in FIG.

The subscriber line transmission unit 1 has a U interface termination capability related to ISDN basic access (hereinafter simply referred to as BA), and its function is performed in a U interface channel unit (hereinafter simply referred to as UCU). The system synchronization and multiplexer (2) is a system timing extraction function performed only on the central office terminal (COT) side when operating the PMT (Primary Rate Multiplexer) in COT-RT mode, and a function for synchronizing data from the UCU to the system timing, It has a function of inserting or extracting B-channel and D-channel data from each subscriber into a predetermined time slot, which is mainly performed in a synchronization circuit unit (hereinafter simply referred to as SNU).

The maintenance unit 5 receives the BA related maintenance information terminated from the CPU (Central Processing Unit) from the CPU and inserts and extracts the DS1 frame into a specific time slot, and is referred to as a maintenance unit (hereinafter referred to as a simple MTU). ) Is performed. The trunk interface unit 4 has a DS1 signal termination function and its function is performed in the trunk interface unit (hereinafter simply referred to as TIU).

The subscriber line transmitter 1 has 10 (North American) or 12 (Europe) ISDN basic access capabilities, and two ISDN subscribers are accommodated in one UCU, so that the subscriber line transmitter 1 has 5 or 6 It consists of a UCU.

The main functions of UCU include two-line transmission function by echo cancellation method (ECM), line encoding / decoding function, framing / reframing function, maintenance information exchange and CPU interface function using C channel, and C channel information exchange. It includes multiframing / reframing functions, pulse code modulation (PCM) bus insertion and extraction of B- and D-channel data, channel loopback and frame loss detection / reporting.

On the other hand, the U interface multiframe for transmitting and receiving maintenance information through the C channel is composed of 12 frames, the structure is shown in FIG. C-channel data consisting of 12 bits extracted from 12 frames includes 1-bit multi-frame frame bits, 4-bit A-channel bits (A1-A4), 3-bit M-channel bits (M0-M2), and bits (CR0- CR3). Here, the A-channel data is BA (Basic Access) -related maintenance information as shown in Table 1, and the CRC check bits are polynomial 1+ using a data sequence of 224 bits except the frame bit and the CRC check bits among the previous multiframe bits. Represent the remainder of the polynomial divided by X + X ⁴ . The CRC bits are used to extract transmission parameters (BER, EFS) of the U interface digital link and report them to the upper network. The MO bit indicates a major alarm state, and the M1 bit is used as a bit for reporting an abnormal state to a higher network when the other station determines that an error exists as a result of a CRC check on a previously received multiframe. The main types of maintenance information related to BA are the impossible of normal communication such as reception signal loss, frame synchronization loss, excessive error condition, remote alarm indication (hereinafter simply referred to as RAI), alarm indication signal (hereinafter simply referred to as AIS), and reception signal. There are alarm status information, loopback and maintenance information for fault isolation such as activation / non-operational requirements.

TABLE 1

The system synchronization and primary rate multiplexer (PMUX) synchronization in the multiplex 2 is based on the 8 Kbps timing recovered from the UCU from the U interface deren coming from the ISDN exchange connected to the PMUX COT.

Center Office Terminal (COT) synchronization selects one of the 12 or 10 8KHz reference timings coming from each UCU, the one with the best state in SNU, and sends it to the TIU to generate 1.544 or 2.048Mbps timing. By doing so. The synchronization on the RT (Remote Terminal) side is achieved by generating a reference 8KHz timing from the 1.544 or 2.048Mbps timing recovered from the data received at the trunk and using it as the system timing. On the other hand, the system synchronization and multiplexer (2) is a phase difference occurring between the system timing on the PMUX COT side and the 8KHz timing recovered from the UCU, so that data from the UCU is not completely synchronized with the system timing, thereby synchronizing it with the system timing. It has a function of inserting or extracting B-channel and D-channel data from each subscriber into a predetermined timeslot in a frame (see FIGS. 3 and 4).

The trunk interface unit 4 is mainly composed of TIUs that transmit and receive DS1 level signals and is designed to be compatible with North American and European methods by replacing the unit.

Transmitter is a transmission time slot allocator for converting data of B and D channels of each subscriber coming in the form of three PCM buses into corresponding timeslots of the frames shown in Figs. It consists of a DS1 transmitter and a line driver, and the receiver is a DS1 shot haul interface unit for terminating DS1 signals and reproducing clock and data, DS1 class rerambling function and line code decoding function. DS1 receiving unit, and a receiving time slot allocating unit for allocating each subscriber information to a timeslot on the PCM bus, and the microprocessor interface unit exchanges information of line status, alarm state of DS1 signal, and DS1 related control. It performs the function of providing information.

In North American frames, as shown in Table 2 below, ESF (Extended Super Frame) is a 24-frame multiframe system that provides a data link for maintenance between devices and introduces a CRC code for evaluation of transmission performance. The European frame is adopted and the 16-frame multi-frame method recommended in CCITT G.704 is adopted. On the other hand, B8ZS (Binary 8 Zero Suppression) is adopted in North America and HDB3 (High Bipolar 3Code) line code is adopted in order to guarantee clear channeled capacity.

Types of trunk related maintenance information include received signal loss detection, frame synchronization loss detection, power loss detection, excessive error condition detection, key alarm related information such as AIS count, RAI reception, maintenance information such as loopback, and CRC. Transmission performance monitoring information using code. For maintenance on Trump, the North American approach used ESF facility data links, the European approach used A and Si bits, and the North American RAI used a pattern on the data link (111111110000000). By transmitting continuously, the European RAI is achieved by sending the A bit set to "1".

TABLE 2

The common controller 3 is composed of a CPU for smoothly performing the functions of the PMUX, and the CPU function is a 16-bit high-speed signal processing function (using the MC 68000 CPU) for processing various signals and software required for the PMUX function. , Program and data (16K byte ROM, 16K byte RAM) maintenance and storage function, facility information exchange function between partner stations through facility data link between PMUX COT and RT (using MC 68561), BA related maintenance with UCU There is exchange of maintenance information, exchange of alarm information of DS1 level with TIU, provision of tie slot information, and exchange of maintenance information related to trunk with MTU.

Maintenance information such as A1-A4 and M0-M2 received from the UCU is terminated in the CPU and analyzed. If the CPU needs to send this information to the other station, the CPU sends it to the maintenance department, which has a function of inserting and extracting this information into the A1-D1 and M0-M7 timeslots assigned to each subscriber.

As shown in FIG. 3 and FIG. 4, a 1-bit parity check bit is provided to protect A1-D1 and M0-M7 bits allocated to each subscriber from errors occurring in the transmission path. Only if the tee test result is good, the A1-D1 and M0-M7 bits are stored in the buffer. In the case of A1-D1 data, the first received A1-D1 data is different from the second received A1-D1 data after collecting the three subblocks of A1-D1 data, and the second received A1-D1 data is received secondly. Only when the A1-D1 data is the same, and all three A1-D1 data have good validity results, the CPU interrupts and delivers the M0-M7 data once every certain time (North America: Mmsec Europe: 2 msec). Interrupt it and deliver it. For reference, the uses of the A1-D1 and M0-M7 bits of the DS1 frame are shown in Tables 3 and 4.

TABLE 3

TABLE 4

5 is an exemplary diagram showing a case where the present invention is directly connected to an ISDN exchange, and shows that the present invention primary rate multilexer (PMUX) is directly connected to a local ISDN exchange through a digital link. The other end of the PMUX is connected to the subscriber-end network terminator (hereinafter simply referred to as NTE). 160Kbps channel information from Network Terminationg Equipment (NTE) is converted to 2.048Mbps in Europe and 1.544Mbps in North America through PMUX and multiplexed to the exchange.

FIG. 6 is an exemplary diagram when operating with the COT-RT board of the present invention, in which PMUX / COT is connected to the exchange side and PMUX / RT is connected to the NTE subscriber side, so that channel information coming from the NTE is PMUX / COT and PMUX. The system between / RTR is multiplexed and transmitted through the data link, and the PMUX / COT side is finally configured to transmit and receive channel information to the exchange.

7 is a functional block diagram of a PMUX TIU.

As shown in FIG. 7, the PMUX TIU includes a line interface 11, a trunk interface 12, a multi-switch circuit 13, a microprocessor interface 14, a trunk controller 15, and an alarm detection and display circuit 16. It consists of).

Data received from the line is interfaced via the line interface 11 and the trunk interface, and is transmitted and received with the UCU through the multi-switch circuit 13 controlled by the microprocessor.

8 is a functional block diagram of a PMUX CPU. The MPU (microprocessor) uses a Motorola MC 68000 and is configured to operate with a 12 MHz system clock.

In the system clock generation and reset signal generation unit, clock generation is used by dividing the clock of the oscillator generating 24 MHz, and the reset signal generation asserts the reset and the hold line of the microprocessor at the same time.

If the MC68000 microprocessor accidentally attempts to access an address without a device or memory, or if the DTCAK or VPA cannot be returned due to surrounding factors, the transfer cycle is delayed indefinitely and the system stops running. To prevent this, it is necessary to inform the microprocessor of this condition and cope with it. The circuit consists of four flip-flops and is used as a shift register.

This circuit is cleared by the assertion of the address strobe (hereinafter simply referred to as AS), 1D becomes "H", and the "H" level is transmitted to the next step by the next clock. In other words, if AS remains asserted for four clocks, the output Q of the last flip-flop is at the “L” level, asserting the microprocessor's BERR (bus error). When the microprocessor detects a BERR, the microprocessor interrupts any running bus cycle, closes the bus error vector and executes the routine specified by the vector.

The interrupt processor receives the interrupt signals from the peripheral peripheral circuit, the programmable timer module (hereinafter simply referred to as PTM), and the asynchronous communication interface adapter (hereinafter simply referred to as ACIA), and provides signals to the microprocessor for interrupt signal processing.

The processor interrupt request is executed by three signal lines. The interrupt request signals from the external peripheral circuit, PTM, and ACIA are converted into binary codes by the priority encoder 74LS148 and input to the microprocessor.

The 68000 microprocessor uses asynchronous communication. The DTACK signal must be input as the input / output completion signal of the data.

In particular, in the 6800 series peripheral circuit, DTACK is generated in the circuit itself, but the DTACK signal of the memory device is generated to be suitable for the access time. This part was constructed using 74LS175.

The memory uses two 27256 (32K ROM) and two 62256 (32K RAM), where the OS (MTOS: Multi Task Operating System) and Layer 1 (Layer1), Layer 2 (Layer2) and Layer 3 (Layer3) The program is built in.

The timer uses the MC6850 (Programmable Timmer Mocule) to generate the periodic interrupts required by the operating system and the transmit (Tx) and receive (Rx) outputs of the ACIA (MC6840).

The microprocessor interface unit of the PMUX TIU (see FIG. 7) transmits and receives signals of the microprocessor's data bus, addresser bus, and necessary controls for matching to the TIU and UCU cards.

FIG. 9 is a diagram illustrating an example of the configuration of the UCU in the PMUX COT. In this figure, only main parts are shown.

The exchanger is capable of transmitting and receiving via a two-wire line, and is converted to have a 160 Kbps speed through the two-wire line, and is then converted by the U transceiver 22 into an ST bus format of 2.048 Mbps or 1.544 Mbps. The U transceiver has a 10.24 MHz phase locked loop (PLL) circuit to operate in slave mode to the master mode of the exchange.

The channel separation / insertion circuit 23 separates the 2B + D + C channel information from the U transceiver into 2B + D channels and C channels, and then sends the 2B + D channels to the SNU (Synchronous Circuit Unit). Send to.

In addition, it is another embodiment of the configuration of the UCU at RT received from the SNU, only the main part is shown in this figure. As can be seen in the figure, the UCU of PMUX RT is equipped with the hybrid circuit 24, the U transceiver 25, and the channel separation / insertion circuit 26 to perform the same function as the UCU in the COT of FIG. do.

FIG. 11 is a diagram showing a frame format on a U transceiver line, and FIG. 11B is a timing relationship diagram of a system clock and a 2.048 Mbps data stream.

Data on the incoming line at 160 Kbps is converted to 2.048 or 1.544 Mbps data via UCU and transmitted to TIU in the frame format as shown in the figure, and TIU transmits this data information to exchange or PMUX RT through data link. .

The present invention is configured as described above, 10 or 12 ISDN basic access subscribers scattered in a remote group in the DS1-class bit rate multiplexed to the ISDN switchboard, especially in the initial ISDN adoption area where the ISDN exchange is not installed Subscribers can use the existing DS1 transmission facility to provide efficient and economical ISDN service.

Claims (2)

Subscriber multi-device for providing ISDN 2B + D-class services to multiple ISDN basic access subscribers distributed in remote areas, for terminating multiple U-interface lines and for separating or inserting C channels. Subscriber line transmission means (1) having a plurality of U-interface channel unit (UCU), synchronizes the data received from the subscriber line transmission means to the system timing and the B-channel and D-channel data coming from each subscriber It is connected between the system synchronization and multiple means (2), the system synchronization and multiple means (2), and the trunk having a plurality of synchronization circuit units (SNU) for insertion or extraction in a preset time slot. A trunk interface means (4) having a TIU for transmitting and receiving DS1 level signals, and a central processing unit (CPU) And exchange basic maintenance related maintenance information with the subscriber line transmission means (1), exchange information and time slot information with the trunk interface means (4), and provide information for maintenance. A common control means (3) and a maintenance unit (MTU) to receive basic access (BA) related maintenance information from the common control means (3) to insert or extract in a specific time slot of a DS1 class frame. Medium ISDN subscriber multi-device, characterized in that consisting of the maintenance means (5). The 8KHz reference timing signal according to claim 1, wherein the system synchronization and multiple means (2) is one of the best state of the plurality of 8KHz reference timings from which the synchronization circuit unit (SUN) comes from the U interface channel unit (UCU). And the selection signal is supplied to the trunk interface means to achieve system synchronization.

Images