CN119011028A - Burst data equal probability coding and decoding method for optical communication - Google Patents

Abstract

The invention belongs to the technical field of coding and decoding methods, and discloses a burst data equiprobability coding and decoding method for optical communication, comprising the following steps: sending a burst mode signal through a local host computer; receiving the burst mode signal through a coding module, and processing the burst mode signal through the coding module; transmitting the burst mode signal processed by the coding module to a filter for filtering and shaping processing; and then transmitting the electric signal after filtering and shaping processing to a comparator for processing. The invention can reduce the peak-to-average power ratio of the burst mode data and reduce the signal distortion that may be caused by the signal strength fluctuation through the burst mode data coding and decoding method, and because the signal mean value is fixed after coding, the zero-crossing judgment method can be selected in the link AC coupling mode, and the zero-crossing judgment can improve the response speed and has good anti-interference performance for a certain degree of noise and other interference.

Description

Burst data equal probability coding and decoding method for optical communication

Technical Field

The invention belongs to the technical field of coding and decoding methods, and particularly relates to an optical communication-oriented burst data equal-probability coding and decoding method.

Background

In recent years, burst mode data transmission methods are increasingly being applied to optical fiber communication systems. Burst mode signals are a signal mode in which information is transmitted at a high data transmission rate in a short time, and are commonly used in wireless communication technology. This mode is characterized by fast data transmission in a short time, then entering a longer quiet period, and then fast data transmission again. This mode is very useful in situations where a large amount of data needs to be transmitted quickly, because it can efficiently utilize radio spectrum resources in a short time, and is particularly widely used in technologies such as optical burst switching and optical packet switching.

The peak-to-average power ratio is an important consideration when transmitting burst mode data. The peak-to-average power ratio refers to the ratio between the peak power and the average power of a signal. The peak-to-average ratio problem is a common problem in multi-carrier modulation, for example, in OFDM systems, since the symbol is formed by overlapping a plurality of independently modulated sub-carrier signals, when the phases of the sub-carriers are the same or similar, the overlapping signals generate larger instantaneous power peaks, thereby bringing about a higher peak-to-average power ratio. Such high peak-to-average ratio may cause the signal to enter the nonlinear region of the power amplifier, generating nonlinear distortion, causing spectrum spread interference and in-band signal distortion, severely affecting system performance. In single carrier modulation, although the problem of PAPR is not as pronounced as in multi-carrier modulation techniques. However, the single carrier modulation technique still has some problems related to peak-to-average ratio, and the PARR problem needs to be solved.

The equal probability coding is a coding scheme in which the probability of occurrence of each data symbol is the same. The coding mode can reduce PARR, and high PAPR may cause larger distortion of the signal in the transmission process, thereby affecting the reliability and efficiency of the signal. Meanwhile, unequal data are encoded into equal probability, so that the average value of the signals can be fixed, and the reliability of data transmission can be improved.

Decision level and bit error rate are two key concepts in digital communication systems that are directly related to the reliability of data transmission and system performance. Decision level refers to a threshold value used by a receiver to determine whether a received signal represents a logic "1" or a logic "0" in a digital communication system. The receiver interprets the signal as a "1" when its amplitude exceeds the decision level, and as a "0" when its amplitude is below the decision level. The bit error rate refers to the proportion of errors occurring in bits transmitted over a certain period of time. It is an important indicator for measuring the performance of digital communication systems. Bit error rate is affected by a number of factors including signal power, noise level, characteristics of the transmission medium, modulation scheme, coding scheme, and setting of decision levels.

Burst mode data transmission is increasingly being used in optical fiber communication systems. For burst mode receivers, dc coupling is typically used to process signals containing dc components, while ac coupling is used for signals containing only ac components. In the receiver, the choice of decision level is critical, as it determines whether the signal is to be judged as a "1" or a "0". In dc coupling, since the signal contains a dc component, the setting of the decision level may need to take into account the influence of the dc bias. In ac coupling, however, the decision level may be simpler to set since the signal does not contain a dc component, since only the amplitude of the ac signal has to be taken into account. In addition, the dc coupling may be affected by dc bias variations and low frequency noise, which may complicate the decision level selection. Therefore, an optical communication-oriented burst data equal probability coding and decoding method is provided to solve the problems.

Disclosure of Invention

The invention aims to provide an optical communication-oriented burst data equal-probability coding and decoding method so as to solve the problems in the background technology.

In order to achieve the above purpose, the present invention provides the following technical solutions: an optical communication-oriented burst data equal probability coding and decoding method comprises the following steps:

s1: transmitting a burst mode signal through a local upper computer;

S2: receiving the burst mode signal by the coding module, and processing the burst mode signal by the coding module;

S3: transmitting the burst mode signal processed by the coding module to a filter for filtering and shaping;

S4: the electric signal after the filtering and shaping treatment is transmitted to a comparator for processing, and then the electric signal is transmitted to a direct modulation laser through the comparator;

S5: transmitting an optical signal by directly modulating a laser, receiving the optical signal by an APD, and converting the optical signal into an electrical signal by the APD;

s6: amplifying the electric signal through a trans-impedance amplifier, and inputting the amplified electric signal into a filter for filtering;

S7: inputting the filtered electric signals into a decoding module for decoding, and extracting burst signal data streams sent by a transmitter from the electric signals;

s8: and then receiving the burst signal data stream through the remote upper computer.

Preferably, the APD is an avalanche gain photodiode.

Preferably, the coding module comprises an MCU master control singlechip, a D trigger and an exclusive OR operation unit.

Preferably, the decoding module comprises a filtering unit, a self-delay unit, an exclusive nor operation unit, a rising edge inversion unit and a comparator.

Preferably, the step S2 specifically includes the steps of:

S21: the MCU receives a burst mode signal sent by a local upper computer, generates a clock signal with the frequency twice the baud rate of the burst signal, and transmits the clock signal to the D trigger;

S22: the D trigger delays the signal to be transmitted for a short time, and the burst signal and the clock signal are synchronized;

S23: finally, the burst data synchronized with the clock is exclusive-ored with the clock, and the burst signal is encoded into a series of data streams with 0,1 and the like and fixed average value after the exclusive-ored operation.

Preferably, the step S7 specifically includes the steps of:

S71: firstly, shaping such as filtering is carried out on the electric signal, and then a bit width is delayed;

S72: then performing exclusive OR operation on the signals before and after the delay;

S73: and then the result of the AND operation is processed by rising edge inversion, and the burst signal data stream sent by the sender is extracted from the received signal.

Compared with the prior art, the invention has the beneficial effects that:

The invention can reduce the peak-to-average power ratio of burst mode data, reduce signal distortion possibly caused by signal intensity fluctuation, and can select a zero-crossing judgment mode under a link alternating-current coupling mode due to fixed signal mean value after encoding, and the zero-crossing judgment can improve response speed and has good anti-interference performance on noise and other interference to a certain extent.

Drawings

FIG. 1 is a schematic diagram showing the comparison of waveforms transmitted by the present invention and conventional method;

FIG. 2 is a functional block diagram of a transmitter of the present invention;

FIG. 3 is a schematic view of waveforms of points of the present invention;

Fig. 4 is a functional block diagram of a receiver of the present invention.

Fig. 5 is a schematic diagram of waveforms at various points of the receiver according to the present invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Referring to fig. 1-5, the present invention provides the following technical solutions:

Example 1

An optical communication-oriented burst data equal probability coding and decoding method comprises the following steps:

s1: transmitting a burst mode signal through a local upper computer;

S2: the MCU receives a burst mode signal sent by a local upper computer, generates a clock signal with the frequency twice the baud rate of the burst signal, and transmits the clock signal to the D trigger;

S3: the D trigger delays the signal to be transmitted for a short time, and the burst signal and the clock signal are synchronized;

s4: finally, the burst data synchronized with the clock is exclusive-ored with the clock, and after exclusive-ored, the burst signal is encoded into a string of data streams with 0, 1 and the like and fixed average value;

S5: transmitting the burst mode signal processed by the coding module to a filter for filtering and shaping;

s6: the electric signal after the filtering and shaping treatment is transmitted to a comparator for processing, and then the electric signal is transmitted to a direct modulation laser through the comparator;

s7: transmitting an optical signal by directly modulating a laser, receiving the optical signal by an APD, and converting the optical signal into an electrical signal by the APD;

s8: amplifying the electric signal through a trans-impedance amplifier, and inputting the amplified electric signal into a filter for filtering;

s9: firstly, shaping such as filtering is carried out on the electric signal, and then a bit width is delayed;

S10: then performing exclusive OR operation on the signals before and after the delay;

S11: then, the result of the AND operation is processed by rising edge inversion, and burst signal data streams sent by a sender are extracted from the received signals;

S12: and then receiving the burst signal data stream through the remote upper computer.

Embodiment two:

in a metropolitan area network environment based on fiber transmission, the method of the present invention is applied to realize the equiprobable encoding and decoding of burst data. The method comprises the following specific steps:

and (3) signal transmission: the upper computer of the local data center generates a burst mode signal which comprises 0 and 1 data bits distributed randomly and sends the burst mode signal to the optical communication module through an optical fiber interface.

The coding module processes: the coding module is internally provided with an MCU (such as STM32 singlechip), and the MCU immediately generates a clock signal with the frequency twice the baud rate of the burst signal after receiving the signal sent by the upper computer. The D trigger receives the clock signal and the burst signal, and precisely delays the burst signal to ensure synchronization with the clock signal. Then, the exclusive-or operation unit performs exclusive-or operation on the synchronized burst signal and the clock signal to generate an equally probable coded data stream.

Filter shaping and modulation: the encoded data stream is filtered and shaped by a low pass filter to remove high frequency noise and glitches. Then, the signal is sent to a direct modulation laser, and the laser modulates the intensity of the optical signal according to the intensity change of the electric signal, so that the optical signal is sent.

Optical signal reception and conversion: the remote receiving station receives the optical signal using an APD (avalanche gain photodiode) and converts it into an electrical signal. The high sensitivity of APDs ensures that signals can be received efficiently even under low light intensity conditions.

Signal amplification, filtering and decoding: the transimpedance amplifier amplifies weak electric signals output by the APD, and then the signals enter the band-pass filter for filtering, so that noise is further suppressed. The decoding module operates according to the reverse procedure of the encoding module: firstly, a self-delay unit delays signals, and then an exclusive nor operation unit and a rising edge inversion unit extract original burst signal data streams.

And (3) data output: and processing and displaying the decoded burst signal data stream through a remote upper computer to complete the whole communication process.

Embodiment III:

In satellite optical communication systems, the method of the present invention is used to achieve high-speed, long-range burst data transmission. The method comprises the following specific steps:

Signal transmission and coding: and the upper computer of the satellite ground station generates a burst mode signal and performs equal probability coding through the coding module. The encoding process is similar to the embodiment, but may require higher clock frequencies and more accurate synchronization control in view of the particularities of satellite communications.

Spatial light transmission: the encoded optical signals are transmitted to the satellite by a high precision optical transmission system, such as a laser transmitter. In the space transmission process, the optical signal may be affected by atmospheric turbulence, star shielding and other factors, so the encoding method needs to have certain anti-interference capability.

Satellite reception and conversion: photodetectors (e.g., APDs) on the satellite receive the optical signals and convert them to electrical signals. The signal processing system in the satellite performs preprocessing such as amplification and filtering on the electric signal.

Decoding and data transmission: the decoding module on the satellite decodes the signal in a similar manner to the first embodiment to recover the original burst data stream. The decoded data is transmitted back to the ground station or other target receiving station via a satellite communication link.

Embodiment four:

In a laboratory environment, a small optical communication system model can be constructed in order to verify the effectiveness of the codec method of the present invention. The method comprises the following specific steps:

and (3) system building: optical communication links are built using optical fibers, lasers, APDs, transimpedance amplifiers, filters, and the like. The encoding module and the decoding module can be realized by using programmable logic devices such as FPGA or DSP, so as to flexibly adjust parameters and verify the effects of different encoding schemes.

Signal generation and encoding: and generating a burst mode signal for testing by the upper computer and sending the burst mode signal to the coding module for equal probability coding. The coding module sends the coded data stream to a laser for modulation.

Optical signal transmission and reception: the coded optical signal is transmitted to a receiving end through an optical fiber, and the APD receives the optical signal and converts the optical signal into an electric signal.

Decoding and verification: the decoding module decodes the received electric signal to recover the original burst signal data stream. And finally, comparing and verifying the decoded data with the original data, and evaluating the correctness and reliability of the encoding and decoding method.

Fifth embodiment:

in submarine optical cable communication systems, the requirements for reliability and stability of signal transmission are extremely high due to extremely long transmission distances and complex environments. The method of the present invention may be applied in such an environment to ensure efficient transmission of bursty data.

Signal pretreatment: and pre-coding the burst mode signal before data transmission to enhance the anti-interference capability. This may include adding redundancy check bits, using forward error correction codes, and the like.

Deep sea coding: and at the transmitting end of the submarine optical cable, performing equal probability coding on the preprocessed signals by using a high-performance coding module. The coding module may need to be adapted to the characteristics of high humidity, high pressure, etc. of the subsea environment, and be made of waterproof, corrosion-resistant materials and designs.

Amplifying optical signals: during transmission of submarine cables, the optical signal strength may gradually decrease due to attenuation and loss. Therefore, an appropriate optical amplifier is arranged in the optical cable to periodically amplify the optical signal so as to ensure the transmission quality of the signal.

Receiving and decoding: at the receiving end, the optical signal is received by using a high-sensitivity APD, and the electric signal is amplified and filtered by a transimpedance amplifier, a filter and other devices. The decoding module decodes the filtered signal to recover the original burst signal data stream.

Data verification and recovery: and verifying the decoded data, and correcting and recovering by using the redundancy check bit or the forward error correction code if the error code or the loss is found.

Example six:

Wireless optical communication (FREE SPACE Opt ics, FSO) is a communication method that uses laser light to transmit data in free space. The method can be applied to an FSO system to overcome the problems of atmospheric interference, transmission distance limitation and the like.

Adaptive coding: the coding parameters and algorithms are dynamically adjusted according to weather conditions (e.g., fog, rain, snow, etc.) and changes in transmission distance. For example, redundancy check bits are added or more complex coding schemes are used to improve the interference immunity of the signal under severe weather conditions.

Accurate alignment and tracking: FSO systems require precise alignment of the transmitter and receiver to achieve efficient optical signal transmission. Advanced automatic alignment and tracking techniques (e.g., GPS assisted positioning, gyroscopic stabilized platforms, etc.) are utilized to ensure accurate alignment and stable tracking of the transmitter and receiver.

Spatial diversity and multiplexing: spatial diversity and multiplexing techniques are employed in FSO systems to improve the reliability and capacity of data transmission. By installing a plurality of transmitters and receivers and distributing the transmitters and the receivers on different spatial positions, redundant transmission and parallel transmission of signals can be realized, so that the reliability and the transmission efficiency of the system are improved.

Decoding and error correction: an efficient decoding algorithm and error correction mechanism are used at the receiving end to process the received optical signal. Error codes and lost data in the transmission process are detected and corrected by combining the technologies of redundancy check bits, forward error correction codes and the like.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (6)

1. An optical communication-oriented burst data equal probability coding and decoding method is characterized in that: the method comprises the following steps:

s1: transmitting a burst mode signal through a local upper computer;

S2: receiving the burst mode signal by the coding module, and processing the burst mode signal by the coding module;

S3: transmitting the burst mode signal processed by the coding module to a filter for filtering and shaping;

S4: the electric signal after the filtering and shaping treatment is transmitted to a comparator for processing, and then the electric signal is transmitted to a direct modulation laser through the comparator;

S5: transmitting an optical signal by directly modulating a laser, receiving the optical signal by an APD, and converting the optical signal into an electrical signal by the APD;

s6: amplifying the electric signal through a trans-impedance amplifier, and inputting the amplified electric signal into a filter for filtering;

S7: inputting the filtered electric signals into a decoding module for decoding, and extracting burst signal data streams sent by a transmitter from the electric signals;

s8: and then receiving the burst signal data stream through the remote upper computer.

2. The optical communication-oriented burst data equal probability coding and decoding method according to claim 1, wherein the method comprises the following steps: the APD is an avalanche gain photodiode.

3. The optical communication-oriented burst data equal probability coding and decoding method according to claim 2, wherein the method comprises the following steps: the coding module comprises an MCU master control singlechip, a D trigger and an exclusive OR operation unit.

4. The optical communication-oriented burst data equal probability coding and decoding method according to claim 3, wherein: the decoding module comprises a filtering unit, a self-delay unit, an exclusive OR operation unit, a rising edge inversion unit and a comparator.

5. The optical communication-oriented burst data equal probability coding and decoding method according to claim 4, wherein: the step S2 specifically comprises the following steps:

S21: the MCU receives a burst mode signal sent by a local upper computer, generates a clock signal with the frequency twice the baud rate of the burst signal, and transmits the clock signal to the D trigger;

S22: the D trigger delays the signal to be transmitted for a short time, and the burst signal and the clock signal are synchronized;

S23: finally, the burst data synchronized with the clock is exclusive-ored with the clock, and the burst signal is encoded into a series of data streams with 0,1 and the like and fixed average value after the exclusive-ored operation.

6. The optical communication-oriented burst data equal probability coding and decoding method according to claim 5, wherein the method comprises the following steps: the step S7 specifically comprises the following steps:

S71: firstly, shaping such as filtering is carried out on the electric signal, and then a bit width is delayed;

S72: then performing exclusive OR operation on the signals before and after the delay;

S73: and then the result of the AND operation is processed by rising edge inversion, and the burst signal data stream sent by the sender is extracted from the received signal.