JP2000209289A - Digital and optical communication method and its equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute communication by means of simple circuit configuration by detecting plural change points of the symbols of a transmission digital signal, detecting the values of the symbols between the detecting change point to the next, converting them into previously decided digital codes, converting them into high-speed digital signals by every symbol of the signal to be transmitted and multiplexing them. SOLUTION: The change in the respective symbol values of the inputted digital signal S2 is detected by a signal change detecting circuit 4, and the values of the respective symbols are detected and decided by a signal level deciding circuit 5. They are converted into the high speed digital signals by binary digital codes corresponding to the quaternary symbols by an encoding circuit 6, the signals corresponding to the symbols are multiplexed by selective exchange by a code selecting circuit 7, and then, they are outputted to a transmission line from an optical transmitting circuit 8 as a transmission optical signal. The received optical signals are decoded by a decoding circuit 10, the error of the codes is checked by a code error detecting circuit 11, and conversion to the binary digital encoded signals is executed precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital optical communication method and a digital optical communication apparatus for transmitting a digital signal in which a symbol of a signal to be transmitted has a plurality of values by optical communication.

[0002]

2. Description of the Related Art In a case where a signal to be transmitted from a terminal device or a switching device is a digital signal having a plurality of values of symbols due to the magnitude of its amplitude, the digital signal is transmitted at a speed lower than the original transmission speed. Conventionally, when converting to a high-speed digital signal and multiplexing and transmitting by digital optical communication, a signal to be transmitted is converted into a binary digital signal in advance, and then the converted binary digital signal is converted into a digital signal. A method has been adopted in which a high-speed digital signal is multiplexed by being incorporated at a predetermined position in a predetermined format and then transmitted by digital optical communication.

[0003]

However, in the conventional digital optical communication method employing the above-described conversion into a digital signal and multiplexing, the timing at which the value of the symbol of the signal to be transmitted changes is changed. In some cases, the timing of multiplexing deviates from the timing of the multiplexing, and not only the transmission of the signal is delayed due to the deviation of the timing, but also the fluctuation of the transmission time, that is, the occurrence of the delay fluctuation easily deteriorates the quality of the transmitted signal. This is particularly remarkable when the signal to be transmitted has three or more values depending on the amplitude of the symbol.

In the above conventional optical communication method, the transmission delay time is shortened as much as possible, the signal transmission speed is increased in order to reduce the delay fluctuation, and the high-speed digital signal transmitted on the receiving side is transmitted. A signal corresponding to a transmission signal is used as a synchronization signal for converting a signal into a signal corresponding to an original symbol, and a time lag of a signal between transmission and reception is adjusted to suppress deterioration of the quality of the transmission signal. However, in this case, not only the circuit configuration of the entire device becomes complicated due to the need for a synchronization signal extraction circuit and a reproduction circuit, but also the transmission delay due to the above-described timing shift, There is a problem that quality deterioration of the transmission signal due to the fluctuation of the delay time is unavoidable.

Further, in the case of conventional multiplexing in which a converted binary digital signal is incorporated at a predetermined position in a transmission format, the amount of information changes according to the transmission speed of the digital signal to be transmitted. Therefore, in order to enable connection operation with a terminal device or switching device having a different signal transmission speed, a circuit configuration and a transmission / reception device corresponding to the transmission speed are required, so that the entire device is more complicated and communication efficiency is poor. Becomes

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and it is possible to efficiently communicate even signals having different transmission speeds and types with the same and simple circuit configuration, and to shorten the transmission delay time. It is an object of the present invention to provide a digital optical communication method and a digital optical communication capable of suppressing a decrease in signal quality.

[0007]

To achieve the above object, a digital optical communication method according to a first aspect of the present invention comprises a digital signal having a plurality of values according to the amplitude of one transmission signal symbol. A method of converting a signal into a digital signal having a higher speed than the transmission speed of the digital signal, and then transmitting the high-speed digital signal by digital optical communication, wherein a change point of a symbol of the digital signal to be transmitted is detected, It is characterized by detecting the value of the symbol from the detected change point to the next change point, converting it to a signal of a predetermined digital code, multiplexing and transmitting the signal by digital optical communication. And

In the digital optical communication method according to a second aspect of the present invention, a digital code is converted for each of a plurality of symbols having different values depending on the magnitude of the amplitude, and a high-speed digital signal is converted for each symbol. Receiving a digital signal transmitted by digital optical communication after being multiplexed, and decoding the received high-speed digital signal into a plurality of signals corresponding to the original symbol values. The output of a reference signal having an amplitude corresponding to the value of an original symbol prepared separately is switched using the plurality of signals, and is transmitted as a digital signal to a terminal device or a switching device.

A digital optical communication apparatus according to a third aspect of the present invention is a means for encoding a digital signal having a plurality of values according to the amplitude of one transmission signal symbol for each symbol and increasing the speed. A transmitting communication device comprising means for multiplexing the coded / high-speed signal and transmitting the multiplexed signal as an optical signal; and receiving a high-speed digital signal transmitted by the transmitting communication device, Means for decoding into a plurality of signals corresponding to the original symbol, and switching control of the combined plurality of signals to a signal having an amplitude corresponding to the value of the original symbol, and transmitting the signal to the terminal device or the switching device. And a receiving communication device having means.

According to the present invention having the above-described characteristic configuration, a signal having a plurality of value symbols according to the magnitude of amplitude is encoded for each symbol, converted to a high-speed digital signal, and multiplexed. On the other hand, the receiver decodes the high-speed digital signal for each symbol into a plurality of signals corresponding to the original symbol value, and converts the plurality of signals into amplitudes corresponding to the original symbol value. Control signal to be transmitted to the digital signal having the above, even if the transmission speed of the signal to be transmitted is different, and the signal to be transmitted has three or more or four or more values depending on the magnitude of the amplitude. Any kind of digital signal having the symbol can be transmitted efficiently with the same circuit configuration, as well as the conventional one. , Into a binary digital signal,
The transmission delay time can be reduced as compared with the case where the signal is periodically incorporated at a predetermined position in a predetermined format of a high-speed digital signal and multiplexed.

Further, by detecting a change point of the value of a symbol of a digital signal to be transmitted, converting the symbol into a digital code, and transmitting the digital code at that timing, it is possible to suppress the deterioration of the quality of the transmitted signal due to the occurrence of delay fluctuation. In addition, there is no need for a synchronization signal extraction and reproduction circuit to adjust the time lag of the signal on the transmitting and receiving sides,
The circuit configuration and the transmission / reception device can be simplified.

In order to achieve the above object, a communication method according to the first aspect of the present invention is a method for converting a digital signal in which one symbol has two or more values depending on the amplitude of the symbol at an arbitrary transmission rate. When transmitting by optical communication, a change point of a value of a signal to be transmitted is detected, and a value of a symbol at that time or after an arbitrary time until a next change is detected and determined, and is configured by a plurality of bits. Digital optical communication is performed for each symbol of a signal to be transmitted by using a means for encoding a signal by a method of converting it into a digital code and a method of converting and multiplexing the digital code into a higher-speed digital signal. This is a communication method characterized in that the communication method is used for transmission.

A communication method according to a second aspect of the present invention is applied to the reception of a signal described in the first aspect and the above-described method. When a digitally encoded digital optical signal is received, the communication method is applied. After converting the signal into an electric signal, it decodes the received digital code and converts it into a signal corresponding to the original symbol value. Using this signal, switches between a signal having an amplitude corresponding to the symbol value. Control
A communication method characterized by transmitting a signal to a terminal device or a switching device.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a waveform S1 of a digital input signal from a terminal device or a switching device in the digital optical communication method according to claim 1 of the present invention. It is the same as the waveform of the digital output signal to the device.

The symbol of one signal S2 to be transmitted shown in FIG. 1 has four values of "+3", "+1", "-1", and "-3" depending on the voltage value, that is, the magnitude of the amplitude.
And two values, each of which is "1".
It has values of “0”, “11”, “01”, and “00”.

After detecting that the symbol value of one digital signal to be transmitted shown in FIG. 1 has changed, the value after an arbitrary time until the next symbol changes is detected and determined. As shown in Table 1 below, conversion is made to a binary digital code corresponding to the quaternary symbol.

[0017]

[Table 1]

The binary digital code converted as shown in Table 1 is perceived as a digital signal having a higher speed than the transmission speed of the digital signal having the waveform shown in FIG. Figure 2
2A, the position indicated by A in FIG. 2A is a change point of the value of each symbol, and the position indicated by B is the value of each symbol from the change point to the next change point A. The value of each symbol detected at the point B is converted into a binary digital code as shown in Table 1, and the digitally coded signals are converted into the signals shown in FIG.
As shown in (1), a high-speed digital signal is embedded and multiplexed at the position C on the time axis of the optical transmission line D and transmitted by digital optical communication.

On the other hand, when the receiving side receives the high-speed digital signal shown in FIG. 2B transmitted by the above-mentioned digital optical communication, it receives each symbol incorporated in the position C of the optical transmission line D. Is decoded into the signal of FIG. 2A corresponding to the value of the original symbol,
These decoded signals are converted to digital signals S1 of waveform S1 shown in FIG. 1 having an amplitude corresponding to the value of each original symbol.
2, and outputs to the terminal device or the exchange device.

FIG. 3 is a functional block diagram showing a configuration example of a digital optical communication apparatus according to a third embodiment of the present invention. The digital optical communication apparatus 1 is a combination of a transmission communication apparatus 2 and a reception communication apparatus 3. It becomes. The transmitting communication device 2
A signal change detection circuit 4, a signal level determination circuit 5, an encoding circuit 6, a code selection switching circuit 7, and an optical transmission circuit 8;
Further, the receiving communication device 2 includes an optical receiving circuit 9, a decoding circuit 10, a code error detecting circuit 11, an output signal switching circuit 12, and a reference signal generating circuit 13.

In the transmission communication device 2, the signal change detection circuit detects a change in the value of each symbol in the digital signal S2 input from the terminal device or the switching device on the transmission side (not shown). Are detected and determined by the signal level determination circuit 5, and then, as shown in Table 1 in the encoding circuit 6, the binary digital code corresponding to the quaternary symbol is converted into a high-speed digital code. Convert.

Next, a signal corresponding to each symbol output from the encoding circuit 6 is selectively switched by the code selection circuit 7 to change the signal on the time axis of the optical transmission line D as shown in FIG.
Is multiplexed as a high-speed digital signal at the position of, and is output from the optical transmission circuit 8 to the transmission line as a transmission optical signal.

On the other hand, the optical signal transmitted via the transmission path is received by the optical receiving circuit 9 in the receiving communication device 2 and converted into an electric signal digital signal. This digital signal is a coded signal, which is decoded or taken out by the circuit 10, decoded, and converted into a signal corresponding to the original symbol. At this time, since a code error is checked by the code error detection circuit 11, the signal is accurately converted into a binary digitally encoded signal. The signal thus combined is input to the output signal switching circuit 12, and
The reference signal generated by the reference signal generation circuit 13 is also input to the output signal switching circuit 12, and is controlled by the output signal switching circuit 12 to switch to a signal having an amplitude corresponding to the value of the original symbol. Is output to the terminal device or the switching device on the receiving side.

[0024]

As described above, according to the present invention,
Since a low-speed digital signal is converted to a high-speed digital signal and multiplexed for optical communication, a digital signal having a plurality of value symbols depending on the amplitude can be transmitted for each symbol. . Thereby, even if the signals have different transmission speeds, and if the signal type is any type of digital signal having a ternary value or a quaternary value or more in one symbol, other than a binary digital signal, Can be transmitted efficiently with the same circuit configuration, and can be converted into a binary digital signal as in the prior art, and this can be periodically transmitted to a predetermined position in a predetermined format of a high-speed digital signal. The transmission delay time can be reduced as compared with the case where the transmission multiplexing is performed by incorporating the multiplexing into the multiplexing. In addition, a synchronization signal extracting and reproducing circuit for adjusting a time lag of a signal between transmission and reception in order to detect a changing point of a symbol value of a digital signal to be transmitted and to transmit at that timing. Is completely unnecessary, and the circuit configuration and the transmission / reception device can be made very simple.

In addition, by adopting a function of checking a code error of each symbol of a high-speed digital signal for reception on the receiving device side, communication accuracy can be further improved in addition to the above effects.

[Brief description of the drawings]

FIG. 1 is a waveform diagram showing an example of a digital signal to be transmitted in a digital optical communication method according to claim 1 of the present invention.

FIGS. 2A and 2B are diagrams for explaining a method for speeding up and multiplexing a digital signal to be transmitted.

FIG. 3 is a functional block diagram showing a configuration example of a digital optical communication device according to claim 3 of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 digital optical communication device 2 transmission communication device 3 reception optical communication device 4 signal change detection circuit 5 signal level determination circuit 6 encoding circuit 7 code selection switching circuit 8 optical transmission / reception circuit 9 optical reception circuit 10 decoding circuit 11 code Error detection circuit 12 Output signal switching circuit 13 Reference signal generation circuit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04J 14/04 14/06 (72) Inventor Fumitaka Uchino 3-14-40 Senrioka, Settsu-shi, Osaka Toko Seiki F term in reference (reference) 5K002 AA01 AA03 BA03 DA01 DA06 FA01 5K029 AA11 AA18 CC04 FF02 GG03 HH08 HH24

Claims (4)

[Claims] 1. After converting a digital signal having a plurality of values according to the amplitude of one transmission signal symbol into a digital signal faster than the transmission speed of the digital signal, the high-speed digital signal is converted into a digital optical communication signal. A plurality of changing points of a symbol of a digital signal to be transmitted, and detecting a value of the symbol from the detected changing point to the next changing point, and A digital signal characterized by converting into a predetermined digital code, converting the converted digital code into a high-speed digital signal for each symbol of a signal to be transmitted, multiplexing and transmitting the digital signal through digital optical communication. Optical communication method. 2. A plurality of symbols having different values depending on the magnitude of the amplitude are converted into a digital code, and each symbol is converted into a high-speed digital signal, multiplexed and transmitted by digital optical communication. This is a method of receiving a digital signal, which decodes the received high-speed digital signal into a plurality of signals corresponding to the original symbol values, and decodes the decoded signals using a reference signal prepared separately. A digital signal having an amplitude corresponding to the value of the symbol, and transmitting the digital signal to a terminal device or a switching device. 3. A means for encoding and speeding up a digital signal having a plurality of values according to the magnitude of its amplitude in one transmission symbol for each symbol, and multiplexing the coded and speeded-up signal into an optical signal. A transmitting communication device comprising means for transmitting as a signal; and a means for receiving a high-speed digital signal transmitted by the transmitting communication device and decoding each signal into a plurality of signals corresponding to the original symbols. And a communication device for reception provided with means for controlling the switching of the plurality of decoded signals to a signal having an amplitude corresponding to the value of the original symbol and transmitting the signal to a terminal device or a switching device. A digital optical communication device characterized by the above-mentioned. 4. The digital optical communication apparatus according to claim 3, wherein said reception communication apparatus includes means for checking a code error of each symbol of the received high-speed digital signal.