JPH0353732A - Line state identification system - Google Patents

Abstract

PURPOSE:To take a recovery countermeasure quickly by extracting an identification code included in a training signal from a slave station MODEM so as to specify a slave station and a line having a fault immediately when a line fault is detected from the quality of a reception signal. CONSTITUTION:A slave station has an ID code as an address to identify the slave station and the code is included in a training signal sent to a master station MODEM when the slave station MODEM 12 starts communication. A master station MODEM 10 detects the quality of the reception signal from the slave station MODEM received by a reception detection means 18 and informs the slave station and the fault occurrence line to a network service processor from the ID code for identifying the slave station obtained at the reception of the training signal when the MODEM 10 detects a fault such as the line fault.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a line status identification method for identifying the line status of each slave station in a multipoint system that sequentially transmits data from a plurality of slave stations according to a polling procedure on the master station side. In order to quickly identify line failure points without interfering with data transmission with other slave stations, the slave station identification code is included in the training signal sent from the slave station modem to the master station before transmitting user data. The slave station identification code included in the training signal received by the master station modem is extracted to identify which slave station is currently receiving data transmission through which line.

[Industrial Field of Application] The present invention relates to a line status identification method for identifying the line status of each slave station in a multipoint system in which data is transmitted sequentially from a plurality of slave station terminals according to a polling procedure on the master station side.

In a multipoint system in which data is sequentially transmitted from multiple slave station terminals to a master station host through an analog telephone line according to a polling procedure, line deterioration characteristics may be affected due to the fact that each slave station uses a different network. Therefore, the automatic equalizer (
AEQ), carrier automatic phase control circuit (CAPC), etc. are initialized and pulled in.

On the other hand, an abnormality such as a line failure during data reception from a slave station can be determined from the reception quality that depends on operating parameters such as the automatic equalizer and CAPC of the master station modem.

However, if the master station modem does not know which slave station modem the received signal came from, even if it detects a line failure based on the reception quality, it will not be able to identify the failed line or slave station, and in a multipoint system, the master station modem itself cannot It is desirable to be able to identify the transmitting side slave station.

[Prior Art] A conventional modem configuration of a multi-point connected system is shown in FIG. 9, for example.

In FIG. 9, 10 is a master station modem, 12-1 to 12-
3 is a slave station modem, which has uplink 200 and downlink 1.
A multipoint connection is made via 00. Master station modem 1
0 modulates the polling data according to the polling procedure from the host, sends it to the downlink +00, and sends it to the slave station modem 1.
2-1 to 12-3 demodulate the modulated signal from the downlink +00 and send polling data to the terminal side, and the terminal side determines whether or not it is being called. Any one of the terminals that has determined the call from the host sends response data, and any of the slave station modems 12-1 to 12-3 that received the data from the terminal first sends a training signal to the uplink 200. The demodulation unit of the master station modem 10 is initialized and pulled in, and then the terminal return data is modulated and sent to the uplink, demodulated by the master station modem 10 and output to the host.

For example, as shown in FIG.
A training signal and a modulated signal of user data are transmitted in the order of 2-2.12-3.

The reason why the training signal is sent before transmitting the user data modulation signal is that in a multipoint system, the network connection differs for each slave station, so the line deterioration characteristics will also differ each time. The slave station first transmits a training signal, initializes the automatic equalizer, CAPC, etc. of the master station modem to cancel the line deterioration factor at that time, and then sends the user data modulation signal. Become.

[Means for solving the problem] However, in such conventional multipoint systems, the line status between the master station modem and each slave station modem cannot be easily known, so it is impossible to easily know the line status between the master station modem and each slave station modem. There was a problem that it was not possible to quickly identify the

The reason for this is that the modulated signal (user data) from the slave station modem generally contains information that can identify each slave station, but the master station's modem itself cannot cancel line deterioration factors. Its main function is to decode modulated signals, and the data content is not particularly considered during these demodulation processes, so even if the user data includes information that identifies the slave station, the modem is considered to be a slave station modem. cannot be recognized.

Of course, it is possible to provide the master station modem with a function to identify the slave station modem from the information included in the user data.
If such a user data or slave station identification function is provided in the master station modem, the modem identification method must be changed for each procedure used as user data, and it can be standardized without being aware of user data. Its advantages as a modem are lost.

For this reason, in conventional multipoint systems, when it is determined that a line failure has occurred based on the reception quality detected by the master station modem, data transmission with all slave stations is temporarily stopped, and the The method used is to perform a loop test with the slave station to identify the location of the fault, which poses the problem of requiring time and effort to recover from the fault.

The present invention has been made in view of these conventional problems, and provides a line condition identification method that can quickly identify failure points in multi-point connected networks without interfering with data transmission with other slave stations. The purpose is to provide

[Means to solve the problem] FIG. 3 is a diagram explaining the principle of the present invention.

First, the present invention provides a plurality of slave stations 12-1, 12-2, . . . , and sequentially transmits data from the slave modems 12-1, 12-2, . . . according to the polling procedure from the master modem 10.

In the present invention for such a multipoint system, from the slave station modem 12-1, 12-2 to the master station modem 1,
slave station identification code setting means 14 for transmitting an identification code that identifies each slave station by including it in the training signal sent prior to the user data modulation signal to the master station modem; from the training signal received by the master station modem; A slave station identification means 16 for extracting a slave station identification code; and a quality detection means 18 for detecting the quality of a signal received by the master station modem 10; The configuration is configured to identify the line status at each time.

Here, the slave station identification code setting means 14 includes the slave station modem 12
-1. At the end of the training signal transmitted from 12-2, an ID code for identifying the slave station is added and transmitted.

Further, the slave station modem 12-1, 12-2 transmits the slave station identification code using the same signal point arrangement as the training signal.

Further, the slave station identification code setting means 14 causes the slave station identification code to be repeatedly transmitted a plurality of times.

Furthermore, each of the slave station identification code extracted by the slave station identification means 16 of the master station and the reception quality detected by the quality detection means 18 is processed by a network service processor (N S
P) to identify and judge the line status.

[Operation] According to the line status identification method of the present invention having such a configuration, the master station modem of a multipoint system extracts the identification code included in the training signal from the slave station modem, so that the modem itself You can identify which slave station modem is currently receiving signals and which line it is using, and if a line failure is detected from the quality of the received signal, you can immediately identify the slave station and the line where the failure occurred. Recovery measures can be taken quickly.

In addition, since the identification code of the slave station is included in the training signal that is shared between modems, there is no need to change the identification function of the slave station identification code of the master station modem according to the user data procedure. A slave station can be identified without impairing the modem's original functions.

[Embodiment] FIG. 2 is a multi-point connection configuration diagram to which the line state identification method of the present invention is applied.

In FIG. 2, 20 is a master station, which is equipped with a master station modem that will be explained later. For the master station 20, a host 26 and a network service processor (hereinafter simply r
NsPj>28-1 is connected.

The host 26 is connected to the master station 20 via a dedicated interface, and the NSP 28-1 is connected to, for example, 2,
Connected via a 400bps dedicated digital line.

Downlink 100 and uplink 200 for master station 20
A plurality of slave stations 22-1, 22-2, and 22-3 are multi-point connected via the slave stations 22-1 to 22-3, and each slave station 22-1 to 22-3 is equipped with a slave station modem, as will be explained later. It will be done. Each of the slave stations 22-1 to 22-3 has a terminal 24-1.
．． 24-2 and 24-3 are connected. Therefore, in this multipoint system, data is sequentially sent to the host 26 from the terminals 24-1 to 24-3 according to a predetermined polling procedure from the master station 20.

FIG. 3 is a block diagram of an embodiment of the slave station of the present invention shown in FIG. 2.

In FIG. 3, the slave station 22 is provided with a slave station modem 12, and the slave station modem 12 includes a main processor 30 and a digital signal processor (hereinafter referred to as II SPJ) 32.
, a filter 34 and a D/A converter 36 are provided. Note that the demodulation side of the slave station modem 12 is omitted.

The main processor 30 divides the user data from the terminal into bit lengths per modulation according to the data transmission speed,
This bit data is converted into coordinate data indicating a signal point on a complex plane using a predetermined mapping circuit,
This coordinate data is output to the DSP 32. Of course, the main processor 30 also performs error correction processing by adding one redundant bit by trellis encoding or the like.

The coordinate signal of the signal point from the main processor 30 is DS
At P32, the real number component Re is added to the amplitude component and the cosine data (C
OSωt) and the image component In are converted into sine data (sinωt) having amplitude components, and the sum of these two converted data is given to the filter 34, and is converted into the transmission band 0.3 to 3.4 KHz of the analog telephone line. After performing filter processing such as band limiting, the signal is converted into an analog signal by the D/A converter 36 and sent to the network 100.

The configuration of such slave station data modem 12 is the same as the conventional one, but in addition to this, in the present invention, when polling is newly performed from the master station, a scramble signal transmitted before sending out user data is added. A handset ID code setting device 14 is provided for including a handset ID code for identifying the handset.

That is, the slave station of the present invention has an ID code as an address for identifying the slave station, and this ID code is not included in the user data, but is stored in the slave station modem 1.
2 is included in the training signal transmitted to the master station modem at the start of communication.

This training signal is used to initialize the AGC, automatic equalizer, CAPC, etc. installed in the master station modem on the receiving side.
This is used for pull-in, etc., and user data follows this training signal.

FIG. 4 is a diagram showing the configuration of a training signal sent from the handset modem 12 of FIG. 3.

In FIG. 4, the training signals are, for example, nQ, n
It is divided into four phases: l, n2, and n3, and for example, signal points A, of the four signal point arrangement shown in FIG.
Use B, C, D, and rA in phase nO
BABJ, rc D C DJ in phase nl, and l'-ABABJ in phase n2, last phase n
3, a scrambled format "rscRZ" in which a predetermined signal point array is scrambled is transmitted.

The phase nO~n in such a training signal
The transmission of the four signal points in step 3 depends on the line deterioration factor of the slave modem connected to the master station at multiple points.
Signal points rA of phases nO and n2 take different values.
B A BJ is fixed, but phase n4
For phase n3, which is performed in scramble format, for example, a certain modem has nl = 10 times and n = 0 times, but a modem with a worse line quality has, for example, n! = 15 times, n3 = 10 times, and so on.

In a point-to-point system where modems are connected one-to-one via a network, the CCIT
The training signal format is defined as an international recommendation by T.T., and cannot be changed arbitrarily to ensure compatibility between modems. However, the multi-point connection modem targeted by the present invention uses a relatively short training signal in order to receive a training signal from a slave unit in response to a call to the master station and perform high-speed pull-in at the master station modem. Therefore, there are no standards set by CCITT or the like, and the training signal format can be freely determined.

In the present invention, the degree of freedom in designing the training signal in such a multi-point connection is effectively utilized, and as shown in FIG. Add an ID code,
After sending this ID code, user data is sent.

The ID code for identifying the slave station included at the end of the training signal is composed of, for example, 6-bit address codes AO to A5 as shown in FIG. 5(b). Similar to the training signal, this 6-bit ID code is transmitted using the four signal point arrangement shown in FIG. 5(a) as is, so the 6-bit ID code is A+ ) (A2 A3
) (A4A5), divided into 2 bits each, as shown in the same figure (
By allocating to the signal point arrangement a), a 6-bit ID code can be sent using three signal points (three symbols).

Furthermore, in the present invention, in order to eliminate errors due to the influence of noise, etc., the 6-bit pattern of the same ID code is sent twice in succession. Therefore, six signal points (six symbols) are used to transmit the ID code as handset address information.

Here, the modulation rate (baud rate) per symbol is 2.
At 400 baud, 6/2,4 is required to transmit 6 symbols.
00=2.5 ms is required, and the training signal becomes longer by this amount.

FIG. 6 is a block diagram of an embodiment of the master station 20 shown in FIG. 1.

In FIG. 6, the master station 20 is provided with a master station modem 10 shown surrounded by a broken line, and the master station modem 10 includes an A/D converter 40, a filter 42, a DSP 44, and a main processor 4.
Consists of 6. That is, the received signal from the uplink 200 is converted into a digital signal by the A/D converter 40, and is provided to the DSP 44 through the filter 42. DSP44 is AGC
It has functions such as circuits, automatic equalizers, CAPC, and phase jitter compensation circuits, and is capable of measuring received signal levels, S/N ratios, intersymbol interference, frequency offsets, phase jitter, etc. of received signals affected by analog line deterioration factors. The received signal point coordinates are calculated from real number data Re as the cosine amplitude or fraction of the received data obtained by canceling the line deterioration factor and imaginary number data In as the sine amplitude data. The received signal point coordinates obtained by the DSP 44 are given to the main processor 46, which uses hard decisions to obtain the correct signal points and/or soft decisions using Viterbi decoding based on trellis encoding on the transmitting side. The determined and error-corrected signal points are converted into bit data using a mapping circuit, and finally demodulated into data in which the bit data of each modulation is connected and sent to the host 26 side. Note that the modulation side of the master station modem for the downlink 100 is omitted.

The configuration of the master station modem 10 is the same as the conventional one, but in addition to this, in the present invention, the DSP 44 is provided with a function to detect the reception of a training signal from the master station modem, and the main station modem 10 is configured to detect the reception of a training signal from the master station modem. Processor 46 is notified. That is, the training signal is normally used to initialize and draw in the AGC circuit, automatic equalizer, CAPC, phase jitter compensation circuit, etc. provided in the DSP 44, and processing by the main processor 46 is not required. Therefore, in the present invention, in order to extract the ID code for identifying the slave station sent from the slave station modem from the training signal on the main processor 46 side, the main processor 46 instructs the main processor 46 to start the training.
6 will be notified. Specifically, since the main processor 46 can detect the signal indicating the switching timing for each phase nO to n3 of the training signal shown in FIG. 4, the main processor 46 receives the detection signal indicating the end of phase n3, which is the last of the training signal. Later, the signal point coordinate data for 6 symbols obtained from the DSP 44 is determined to be an ID code for identifying a slave station, and this signal point coordinate is used by a mapping circuit according to the signal point arrangement shown in FIG. 5(a). The data is used to demodulate code pits with 2 bits per symbol, and 2-bit data for 3 symbols, that is, 6-bit data, is sequentially stored in an internal register.

Here, as shown in Figure 5(b), from the slave station modem, 6
Since the bit ID code is transmitted twice consecutively, the main processor 46 receives two bits of the first three symbols.
When the bit data has been received, the next 3 symbols' worth of 2-bit data are sequentially stored in other registers, and the 6-bit data of every 3 symbols stored in the two registers are compared to find that they match. When the correct ID code for identifying the slave station has been received, it is transferred to the main processor 50 via the data latch 48.

The main processor 50 is a processor provided for communication with the NSP 28-1, and has a master station address by the master station ID code setter 52, and the main processor 50 is a processor provided for communication with the NSP 28-1.
Data communication is always performed using the master station ID code.

Data communication between the main processor 50 and the NSP 28-1 is performed using a dedicated digital line of 2,400 bps or the like.

Furthermore, the main processor 46 has a function as a quality detection means for detecting the quality of the received signal received by the master station modem 10 from the slave station modem.

In other words, the quality of the received signal includes the received signal level, S/N ratio,
These are represented by deterioration factors on analog telephone lines such as frequency offset and phase jitter. Information regarding the equalization factors is provided by the AGC circuit, automatic equalizer, and C
It can be obtained from the operating parameters of APC and phase jitter compensation circuit.

That is, the DSP 44 of the master station modem is initialized by the training signal from the slave modem to cancel line deterioration factors such as received signal level, S/N ratio, frequency offset, phase jitter, etc. Conversely, the degree of line deterioration factors, that is, the signal quality, can be known from the information on cancellation.

The quality of the received signal detected by the main processor 46 based on each operating parameter of the line deterioration factor in the DSP 44 is transmitted to the main processor 5 via the data latch 48.
Transferred to 0. In the main processor 50, information indicating the reception quality obtained during the subsequent reception of user data is obtained in real time in correspondence with the ID code for slave station identification obtained at the time of receiving the training signal.

Then, the main processor 50 compares the reception quality information obtained in real time with a predetermined threshold value corresponding to the ID code for identifying the slave station, and if an abnormality such as a line failure is detected, the main processor 50 sends the reception quality information to the network service processor 28-1. Notify the slave station and the faulty line.

Furthermore, for the main processor 50, the downlink 100
A receiving circuit 54 and a transmitting circuit 56 are provided in order to communicate with other NSPs on the master station side through the network via the uplink 200. That is, the NSP 28-1 shown in FIG. 6 communicates with a plurality of other NSPs 2 through a network consisting of analog telephone lines as shown in FIG.
8-0.28-2 to 28-n.

Here, data communication between NSPs using the network uses a subchannel adjacent to Q, 3 KHz in the analog telephone line frequency band 0.3 to 3.4 KHz, as shown in Figure 8. This is done at a transmission rate of 75 bps.

In addition, the main processor 50 shown in FIG.
Other NSPs to self using 0 subchannels
When receiving an inquiry from the receiving signal 54, the master station I
The response information having the D code is sent to the downlink 100 via the transmitting circuit 56. On the other hand, if the received signal from the receiving circuit 54 does not specify the main processor 50,
The received data is sent as is to the NSP 28-1 without performing any special reception processing.

A network of multiple NSPs using such subchannels allows line failures in the multipoint system under the jurisdiction of a particular NSP to be notified to the NSPs in charge of other multipoint systems or point-to-point systems, and necessary measures can be taken. Measures can be taken.

In addition, in the above embodiment, the 6-bit identification I from the slave station modem is
Although the case where the D code is included in the training signal and sent is taken as an example, the number of bits of the ID code can be appropriately determined as necessary.

Further, although the ID code is transmitted twice to eliminate the influence of noise, it may be transmitted repeatedly, for example, three times or more, and the code obtained by majority vote processing may be used as the correct ID code. Of course, on the upstream side of a multipoint system, high-speed acquisition using a training signal is required, so it is desirable to minimize the ID code included in the training signal in order to make the training signal as short as possible.

[Effects of the Invention] As described above, according to the present invention, it is possible to quickly identify the location of a failure in a network that is affected by multi-point connections without interfering with normal line data communication.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the principle of the present invention; Figure 2 is a multi-point connection configuration diagram of the present invention; Figure 3 is a schematic diagram of an embodiment of the slave station of the present invention; Figure 4 is a slave station transmission diagram of the present invention. Signal configuration diagram; Figure 5 is an ID code signal point arrangement diagram of the present invention; Figure 6 is a configuration diagram of an embodiment of the master station of the present invention; Figure 7 is a diagram of the NSP network configuration on the master station side; FIG. 9 is an explanatory diagram of subchannels for transmission between NSPs; FIG. 9 is a modem configuration diagram for multipoint connection; FIG. 10 is an explanatory diagram of data transmission from a slave station to a master station. In the figure, 10: Master station modem 12. 12-1 to 12-3: Slave station modem 14; Identification code setting means (ID code setting device) ↓ 6: Slave station identification means 18: Reception quality detection means 20: Master station 22-l to 22-3: slave stations 24-1 to 24-3: terminal 26/host 28-0 to 28-n network service processor (NSP) 30. 46, 50: Main processor (MP
U ) 32.44 ・Digital signal processor 34. 42 Filter 3 6: D/A converter 4 0: A/D converter 48: Data latch 52: Master station ID code setter 54: Receiving circuit 56: Transmitting circuit 100: Down line 200 2 Up line (DSP) 10 2nd time 4 - Invented ID code Wabi No. 7, layout diagram Figure 5

Claims (5)

[Claims] (1) In a multipoint system having a plurality of slave station modems (12-1, 12-2) that are multi-point connected to the master station modem (10), the slave station modem (12-1, 12-2) ) to the master station modem (1
slave station identification code setting means (14) for transmitting an identification code that identifies each slave station in a training signal sent prior to transmission of the modulated signal to the master station modem (14);
slave station identification means (16) for extracting the slave station identification code from the training signal received by the master station modem (10); quality detection means (18) for detecting the quality of the signal received by the master station modem (10); A line status identification method characterized in that the line status of each slave station is identified based on the identification code of the slave station received by the master station. (2) The slave station identification code setting means (14) includes the ID code for identifying the slave station at the end of the training signal transmitted from the slave station modem (12-1, 12-2). The line state identification method according to claim 1, characterized in that: (3) The line state according to claim 1, wherein the slave station modem ((12-1, 12-2) transmits the slave station identification code using the same signal point arrangement as the training signal. Identification device. (4) The line status identification system according to claim 1, wherein the slave station identification code setting means (14) repeatedly transmits the slave station identification code a plurality of times. (5) The slave station identification code extracted by the slave station identification means (16) provided in the master station and the reception quality detected by the reception quality detection means are transferred to the network service processor to identify and determine the line status. 2. The line state identification system according to claim 1, wherein: