Optical communication receiver jitter compensation method, system, receiver and optical communication system

Abstract

The application relates to the field of optical communication technology and discloses an optical communication receiver jitter compensation method, a system, a receiver and an optical communication system. The method comprises the following steps: sampling and time slot synchronizing an optical signal received by a photon counting detector to obtain a first signal; performing sampling point compensation processing on the first signal to obtain a second signal; performing downsampling, frame synchronization and deinterleaving processing on the second signal to obtain a third signal; performing time slot compensation processing on the third signal to obtain a fourth signal; and performing signal demodulation and signal decoding on the fourth signal to recover original information. In the demodulation process of the receiver, sampling point level information and time slot level information are fully utilized, two-stage demodulation compensation of sampling point compensation and time slot compensation is carried out, the demodulation performance of the receiver is improved, and the sensitivity of the whole communication system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical communication technology, and in particular to an optical communication receiver jitter compensation method and system, a receiver and an optical communication system. BACKGROUND

[0002] Free Space Optical Communication (FSO) is a communication system that transmits information in free space using light as a carrier. Detectors with photon counting function are often used in FSO systems. The time interval from detecting a photon to forming an electrical pulse is defined as the response time of the photon counting detector. However, the response process of the photon counting detector to each photon cannot be exactly the same, and the response time of each response will inevitably vary. The response time of the single-photon detector fluctuates, which causes the time stamp to be advanced or delayed, and thus cannot accurately reflect the actual arrival time of the photon. We call this phenomenon "detector jitter" (DJ).

[0003] The jitter of the photon counting detector causes the probability density function of the received signal to change significantly compared to the transmitted signal, which is widened in time and flattened in amplitude, showing the characteristics of "widening and flattening". Due to the time-domain widening of the sampled signal, the boundary characteristics become blurred, directly leading to a decrease in the synchronization accuracy of the receiver time slot. Due to the combined effects of detector jitter DJ and time slot synchronization error SE, the originally time-accurate and well-defined transmitted signal is shifted in time and blurred in boundary, resulting in significant differences between the sampled signal and the transmitted signal, ultimately leading to an increase in system bit error rate.

[0004] Therefore, how to solve the problem of the increase in system bit error rate and the decrease in sensitivity of the entire communication system caused by detector jitter and time slot synchronization error has become a problem to be solved. SUMMARY

[0005] The present application relates to the field of optical communication technology, and in particular to an optical communication receiver jitter compensation method and system, a receiver and an optical communication system.

[0006] In a first aspect, the present application provides an optical communication receiver jitter compensation method applied to a free space optical communication system using pulse modulation combined with a photon counting detector, the method comprising:

[0007] sampling and time slot synchronizing the optical signal received by the photon counting detector to obtain a first signal;

[0008] sampling point compensation processing the first signal to obtain a second signal;

[0009] The second signal is down-sampled, frame-synchronized and de-interleaved to obtain a third signal;

[0010] The third signal is time-slot compensated to obtain a fourth signal;

[0011] The fourth signal is demodulated and decoded to recover the original information.

[0012] In a second aspect, the application provides a jitter compensation system of an optical communication receiver, which is used to implement the jitter compensation method of the optical communication receiver provided in the above technical solution.

[0013] A sampling synchronization module is configured to sample and time-slot synchronize the optical signal received by the photon counting detector to obtain a first signal;

[0014] A sampling point compensation module is configured to perform sampling point compensation on the first signal to obtain a second signal;

[0015] A down-sampling and de-interleaving module is configured to down-sample, frame-synchronize and de-interleave the second signal to obtain a third signal;

[0016] A time-slot compensation module is configured to perform time-slot compensation on the third signal to obtain a fourth signal;

[0017] A decoding module is configured to demodulate and decode the fourth signal to recover the original information.

[0018] In a third aspect, the application provides a receiver, which is applied to a free-space optical communication system using pulse modulation combined with a photon counting detector, and is used to implement the jitter compensation method of the optical communication receiver provided in the above technical solution.

[0019] In a fourth aspect, the application provides an optical communication system using pulse modulation combined with a photon counting detector, which comprises the receiver provided in the above technical solution.

[0020] In a fifth aspect, the application further provides a computer program product, which comprises computer instructions stored in a computer readable storage medium. A processor of a computer device reads the computer instructions from the computer readable storage medium, and the processor executes the computer instructions to enable the computer device to perform the jitter compensation method of the optical communication receiver provided in the above technical solution.

[0021] The application has the following beneficial effects: in the demodulation process of the receiver, the sampling point level information and the time-slot level information are fully utilized, and the demodulation performance of the receiver is improved through two-stage demodulation compensation of sampling point compensation and time-slot compensation, thereby improving the sensitivity of the entire communication system.

[0022] Additional aspects of the application, together with the advantages thereof over BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A flow chart of a jitter compensation method for an optical communication receiver according to an example embodiment of the application;

[0024] Figure 2 A schematic diagram of PPM modulation;

[0025] Figure 3 A schematic diagram of a free space optical communication system using pulse modulation combined with photon counting detector;

[0026] Figure 4 A schematic diagram of detector jitter;

[0027] Figure 5 A schematic diagram of pulse spreading of a received signal caused by detector jitter;

[0028] Figure 6 A schematic diagram of synchronization error aggravated by detector jitter;

[0029] Figure 7 A schematic diagram of bit error rate rising and signal to noise ratio threshold increasing caused by detector jitter and synchronization error;

[0030] Figure 8 A schematic diagram of statistical and fitting of a probability density function of a time slot synchronization error SE;

[0031] Figure 9 A schematic diagram of a theoretical derivation process of a sampling point compensation coefficient according to an example embodiment of the application;

[0032] Figure 10 A schematic diagram of a two-stage compensation principle according to an example embodiment of the application;

[0033] Figure 11 A schematic diagram of determining a time slot compensation coefficient according to a statistical value according to an example embodiment of the application;

[0034] Figure 12 A block diagram of a jitter compensation system for an optical communication receiver according to an example embodiment of the application;

[0035] Figure 13 A simulation schematic diagram for verifying performance of a scheme according to an example embodiment of the application;

[0036] Figure 14 A schematic diagram of performance gain brought by a scheme according to an example embodiment of the application under a condition of a detector jitter coefficient of 0.2. ​DETAILED DESCRIPTION

[0037] The specific embodiments of the present disclosure will be described hereinafter by specific examples. Those skilled in the art will easily understand other advantages and effects of the present disclosure from the content disclosed in the specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, but not all the embodiments. The present disclosure can also be implemented or applied by other different specific embodiments, and various modifications or changes can be made to the details in the specification without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present disclosure.

[0038] It should be noted that various aspects of the embodiments described below are within the scope of the appended claims. It should be apparent that the aspects described herein can be embodied in a wide variety of forms and that any specific structure and / or function described herein is merely illustrative. Based on the teachings provided herein one skilled in the art will appreciate that one good aspect can be implemented independently of any other aspect and that two or more aspects can be implemented in combination. For example, a device can be implemented using any number of the aspects described herein. In addition, an apparatus can be implemented using other structure and / or functionality not expressly described herein. One skilled in the art will appreciate that the application can be practiced by other than the described embodiments, which are presented for purposes of illustration and not of limitation.

[0039] To solve the problems of poor demodulation performance of the receiver and low sensitivity of the whole communication system caused by receiver jitter and time slot synchronization error, the embodiment of the present application provides an optical communication receiver jitter compensation method, system, receiver and optical communication system.

[0040] Figure 1 A flowchart of the optical communication receiver jitter compensation method according to an example embodiment of the present application is shown in FIG. 1. As shown in FIG. 1, in an example embodiment, the optical communication receiver jitter compensation method can be applied to a free space optical communication system using pulse modulation combined with a photon counting detector. Figure 1

[0041] Free space optical communication (FSO) is a communication system that uses light as a carrier to transmit information in free space. This system not only has the flexibility of location deployment of wireless communication systems, but also combines the advantages of large bandwidth, high speed, small size, light weight, low power consumption and other significant advantages of optical communication systems, thus showing strong development potential. In recent years, it has become a research hotspot in the field of communication and has been widely explored. ​

[0042] The modulation methods commonly used in free space optical communication include pulse position modulation (PPM), pulse amplitude modulation (PAM), PAM modulation, on-off keying (OOK) and other modulation methods that store information in the position and height of the signal pulse. Taking PPM modulation as an example, Figure 2 The specific implementation of PPM modulation is described in detail.

[0043] Free space optical communication systems exist in many application scenarios that face energy constraints and serious channel attenuation, such as deep space optical communication, underwater optical communication, energy-constrained optical communication, and secure optical communication. These scenarios often have very high requirements for the sensitivity of the communication system. Based on the special needs of the above scenarios, photonic counting detectors are often used in free space optical communication systems. Common photonic counting detectors include single-photon detectors such as single-photon avalanche diodes (SPADs), superconducting nanowire single-photon detectors (SNSPDs), and the like.

[0044] Figure 1 The jitter compensation method of the optical communication receiver shown can include steps S1 to S5, which are described in detail as follows:

[0045] S1, sample and time slot synchronize the optical signal received by the photonic counting detector to obtain a first signal.

[0046] Figure 3 The communication system principle of free space optical communication using pulse modulation combined with photonic counting detectors is shown. In Figure 3 In the transmitter, the signal source is processed by channel encoding, PPM modulation, interleaving, and adding a frame header, and the like, and then the transmitted signal is transmitted through the channel to the receiver. In the receiver, the photonic counting detector detects the optical signal and converts it into an electrical signal. After time slot synchronization, downsampling, frame synchronization, deinterleaving, PPM demodulation, and channel decoding, the original data is recovered.

[0047] S2, sample point compensation processing is performed on the first signal to obtain a second signal.

[0048] The time interval from the detection of a photon to the formation of an electrical pulse by a photon counting detector is defined as its response time, denoted as t. However, the response process of a photon counting detector to each photon is not exactly the same, and the response time of each time is inevitably different. The response time of some photons is shorter, and that of the other is longer.

[0049] The fluctuation of the response time of a single photon detector will cause the time stamp to be advanced or delayed, so that the actual arrival time of the photon cannot be accurately reflected. We call this phenomenon "detector jitter" (DJ), as shown in Figure 4

[0050] In Figure 4 , the time t2 at which the photon detector forms an electrical pulse may be earlier or later than the time t1 at which the photon arrives at the detector, which raises a problem: the pulse originally located within the pulse time slot may be marked outside the time slot. Figure 5 It is further disclosed that the influence of detector jitter is that the probability density function of the received signal has changed significantly compared to the transmitted signal: it is spread in time and flattened in amplitude, showing the characteristics of "widening and shortening".

[0051] Due to the time-domain spread of the sampled signal, its boundary characteristics become blurred, directly leading to a decrease in the synchronization accuracy of the receiver time slot. Figure 6 This effect is intuitively shown: when the detector jitter coefficient is 0.3, the synchronization error (SE) is significantly greater than that without detector jitter.

[0052] Due to the combined effect of detector jitter DJ and time slot synchronization error SE, the originally time-accurate and well-defined transmitted signal has a time offset and a blurred boundary, resulting in a significant difference between the sampled signal and the transmitted signal, ultimately causing the system bit error rate to rise. Figure 7 A schematic diagram of the rise in bit error rate and the increase in signal-to-noise ratio threshold caused by detector jitter and synchronization error. Figure 7 This effect is shown: detector jitter and synchronization error will cause the bit error rate of the communication system to rise significantly. Specifically, when there is no detector error and the time slot synchronization is completely ideal, only 2.8 dB of photons per time slot is required to achieve a bit error rate of 1e-6; when the detector jitter coefficient DJ is 0.2, the required photon number threshold rises to 4.0 dB; if the jitter coefficient DJ further increases to 0.3, the threshold is as high as 4.7 dB.

[0053] ​Therefore, in the embodiment of the present application, after the signal sampling and the time slot synchronization are completed, the sampling points at the time slot boundary are compensated, that is, the embodiment of the present application fully utilizes the information at the sampling point level, and improves the demodulation performance of the receiver and the sensitivity of the whole communication system by the compensation at the sampling point level.

[0054] S3, the second signal is down-sampled, frame-synchronized and de-interleaved to obtain a third signal.

[0055] In the embodiment of the present application, after the second signal obtained by the sampling point compensation is down-sampled, frame-synchronized and de-interleaved, a third signal is obtained.

[0056] S4, the third signal is time slot compensated to obtain a fourth signal.

[0057] Due to the joint action of the detector jitter DJ and the time slot synchronization error SE, the originally time-accurate and boundary-clear transmission signal has time offset and boundary ambiguity, which causes significant difference between the sampling signal and the transmission signal, and finally causes the system bit error rate to increase. Therefore, in the embodiment of the present application, after the down-sampling, frame-synchronization and de-interleaving are completed, the third signal is time slot compensated to obtain a fourth signal.

[0058] S5, the fourth signal is demodulated and decoded to recover the original information.

[0059] In the embodiment of the present application, in the demodulation process of the receiver, the sampling point level information and the time slot level information are fully utilized, and the demodulation performance of the receiver is improved by two-level demodulation compensation of the sampling point compensation and the time slot compensation, so as to improve the sensitivity of the whole communication system.

[0060] Figure 1 The step S2 in the illustrated embodiment can specifically include steps S21 to S23 in one exemplary embodiment, and the first signal is compensated at the sampling point level by the above steps to obtain a second signal, which is described in detail as follows:

[0061] S21, the time slot synchronization error of the photon counting detector and its probability density function are determined.

[0062] The real start time of the received symbol is counted and the estimated start time , the value of the time slot synchronization error is defined as , and the expression is The value of and the number of occurrences of are counted to obtain the probability density function PDF of the time slot synchronization error , that is , as shown in Figure 8 .Figure 8 With oversampling magnification Sampling point width As an example, This represents the standard deviation of detector jitter.

[0063] It is not difficult to see that Figure 8 The time slot synchronization error shown in the figure There is a 99% or higher probability of... The interval, therefore the approximate time slot synchronization error exist Interval.

[0064] S22, determine the sampling point compensation coefficient based on the time slot synchronization error and its probability density function.

[0065] Optionally, in an exemplary embodiment, step S22 may specifically include steps S221 to S224, through which the sampling point compensation coefficient is determined, as detailed below:

[0066] S221, determine the actual start time and actual end time of the current time slot based on the time slot synchronization error;

[0067] S222, determine the actual number of photons in the current time slot based on the actual start time, actual end time, and the number of observed photons at different times;

[0068] S223, Based on the time slot synchronization error and its probability density function, determine the mathematical expectation of the actual number of photons in the current time slot;

[0069] S224 uses the coefficients of the boundary sampling points in the mathematical expectation of the actual photon number in the current time slot as the sampling point compensation coefficients.

[0070] Figure 9 This is a schematic diagram illustrating the theoretical derivation process of the sampling point compensation coefficient, as shown in an exemplary embodiment of this application. The following is based on... Figure 9 Explain the calculation process of the sampling point compensation coefficient when compensating for a single boundary sampling point, using the oversampling factor. Sampling point width For example: Define the number of photons at the four sampling points in the current time slot as follows: The number of photons from the adjacent sampling points on the front side of the current time slot is The number of photons at the adjacent sampling point after the current time slot is .

[0071] Due to synchronization errors, the actual start and end times of the current time slot are respectively and .

[0072] In this embodiment of the invention, using the real photon number of the current time slot, is expressed as the observed photon number at the time instant, the real photon number of the current time slot should be expressed as:

[0073] when the time slot synchronization error the real photon number of the current time slot should be expressed as:

[0074]

[0075] when the time slot synchronization error the real photon number of the current time slot should be expressed as:

[0076]

[0077] Considering all cases of and the probability density function thereof the mathematical expectation of the real photon number in the current time slot is expressed as:

[0078]

[0079] wherein, the expression of

[0080]

[0081] Obviously, it can be seen that and so that , the obtained and are the sampling point compensation coefficients.

[0082] Optionally, in an exemplary embodiment, S224 can include: taking the coefficients of the boundary sampling points in the mathematical expectation of the real photon number of the current time slot as the sampling point compensation coefficients, taking the coefficients of the boundary sampling points in the mathematical expectation as the compensation coefficients of the boundary sampling points at the corresponding positions in the current time slot, and recording the first compensation coefficient set; taking the coefficients of the boundary sampling points in the mathematical expectation as the compensation coefficients of the boundary sampling points at the corresponding positions in the adjacent time slot, and recording the second compensation coefficient set.

[0083] The process of determining the sampling point compensation coefficients will be described in detail below by taking the sampling point compensation of a single boundary sampling point as an example. The width of each time slot is defined as 1, the oversampling ratio (i.e. the number of sampling points in each time slot) is , and the width of the sampling point is ​According to the above definition, the product of and is equal to 1.

[0084] The sampling points of the current time slot from front to back are: ; the sampling points of the previous time slot from front to back are: ; and the sampling points of the next time slot are: .

[0085] When the time slot synchronization error , the real photon number of the current time slot should be expressed as:

[0086]

[0087] When the time slot synchronization error , the real photon number of the current time slot should be expressed as:

[0088]

[0089] Considering all cases of the time slot synchronization error and the probability density function , the mathematical expectation of the real photon number of the current time slot should be expressed as:

[0090]

[0091] wherein, the expression of

[0092]

[0093] wherein, and , so x is a sampling point compensation coefficient in the first compensation coefficient group, y is a sampling point compensation coefficient in the second compensation coefficient group, when single boundary sampling point compensation is performed, the first compensation coefficient group and the second compensation coefficient group each only include one sampling point compensation coefficient.

[0094] It should be noted that Figure 9 is the calculation process of the sampling point compensation coefficient when compensating for a single boundary sampling point, and the calculation process of the sampling point compensation coefficient when compensating for multiple boundary sampling points is the same as that of the compensation coefficient when compensating for a single boundary sampling point, and only more boundary sampling points are added in the previous time slot and the next time slot.

[0095] S23, according to the sampling point compensation coefficient, the boundary sampling point is compensated to obtain a second signal.

[0096] Optionally, in an exemplary embodiment, step S23 can specifically include steps S231 to S234, and the sampling point compensation coefficient is determined through the above steps, which are described in detail as follows:

[0097] S231, for the current time slot boundary of the current time slot, multiplying the photon number of the first boundary sampling point of the current time slot by the corresponding compensation coefficient in the first compensation coefficient group to obtain a first intermediate quantity.

[0098] S232, multiplying the photon number of the second boundary sampling point of the adjacent time slot by the corresponding compensation coefficient in the second compensation coefficient group to obtain a second intermediate quantity; wherein the position of the second boundary sampling point is symmetric to the position of the first boundary sampling point with the current time slot boundary as the axis;

[0099] S233, taking the sum of the first intermediate quantity and the second intermediate quantity as the compensation photon number of the first boundary sampling point of the current time slot boundary of the current time slot;

[0100] S234, traversing all boundary sampling points of all time slots until the boundary sampling point compensation of all time slots is completed.

[0101] In the embodiment of the application, the number of boundary sampling point compensation is defined as Specifically, in single boundary sampling point compensation =1; the specific execution operation is: calculating the first sampling point compensation coefficient x and the second sampling point compensation coefficient y; multiplying the photon number of the first boundary sampling point A of the current time slot boundary by the first sampling point compensation coefficient , and multiplying the photon number of the second boundary sampling point B of the adjacent time slot of the first boundary sampling point A by the second sampling point compensation coefficient , and then summing to obtain the photon number of the compensated first boundary sampling point A. That is, corresponding to Figure 10 . Figure 10 For PPM modulation, the time slot compensation template length is , the oversampling ratio is The two-stage compensation principle diagram is shown as an example.

[0102] For the current time slot, the following operations are performed:

[0103] .

[0104] For the previous time slot, the following operations are performed:

[0105]

[0106] For the next time slot, the following operations are performed:

[0107]

[0108] In the multi-boundary sampling point compensation In the step S1, the specific operation is as follows:

[0109] Calculate the first compensation coefficient set , ,…… and the second compensation coefficient set , ,…… ; these coefficients refer to the coefficients of the values of the boundary sampling points in L . Taking L B =2 as an example, respectively refer to the coefficients of P . The mathematical expectation of the real photon number of the current time slot is as follows:

[0110]

[0111] wherein P -1 and P0 are two boundary sampling points of the previous time slot, P1, P2, P3 and P4 are sampling points of the current time slot, and P5 and P6 are two boundary sampling points of the next time slot. Therefore, constitute the first compensation coefficient set, constitute the second compensation coefficient set.

[0112] When the sampling points of the current time slot are sampling points 5, 6, 7 and 8, the specific operation of the multi-boundary sampling point compensation (taking two boundary sampling points as an example) is as follows:

[0113]

[0114] When the next time slot becomes the current time slot, i.e., sampling points 9, 10, 11 and 12 become the current time slot, the specific operation of the multi-boundary sampling point compensation is as follows:

[0115]

[0116] In the embodiment of the application, the time slot compensation template length is 3 time slots, and in actual application, it can be extended to a longer template, i.e. .

[0117] Optionally, in an example embodiment, Figure 1 In the step S4 of the embodiment shown, the time slot compensation processing can be performed on the third signal based on the limited interval Poisson approximation method to obtain the fourth signal, and specifically can include the following steps:

[0118] S41, determine a time slot compensation template: according to the channel condition, a set of coefficient templates with a length of L S (L S ≥3) is calculated in advance to determine the template, and the method for determining the template is as shown in Figure 11(by As shown in the example, the steps are as follows:

[0119] S411, count the number of photons in the current time slot of the received symbols, and the previous... Each time slot and after The number of photons per time slot.

[0120] It should be noted that the embodiments of the present invention can obtain the photon count of different time slots through simulation. For example, a pulse signal at a fixed position is generated through simulation, and then the average photon count of each time slot is calculated based on the signal strength and noise intensity of the real channel. Then, a random photon count conforming to a Poisson distribution is generated with the average photon count as the mean. According to the detector jitter intensity in the real channel, a random arrival time is generated for each photon (i.e., a jitter offset is added to the ideal photon arrival time), thereby extracting the photon count of different time slots.

[0121] In this embodiment of the invention, an optical signal can also be transmitted through a transmitter of a real free-space optical communication system, transmitted through a real channel, and then received by a receiver, thereby extracting the number of photons in different time slots.

[0122] by For example, the statistical results are recorded as follows:

[0123]

[0124] S412 normalizes the statistical results in S411. For example, the specific operation is as follows:

[0125]

[0126] income This is the time slot compensation coefficient.

[0127] S42, extract the photon count of the current time slot, and the previous... Each time slot and after The number of photons per time slot;

[0128] S43, the number of photons extracted in S42 is compared with the corresponding time slot compensation coefficient in the time slot compensation template in S41 (i.e. ...) Multiply the values ​​bit by bit and sum them to obtain the compensated number of photons in the current time slot;

[0129] S44, by traversing all time slots through a sliding window, completes the compensation for all time slots globally, such as... Figure 10 The "time slot compensation" step is shown in the middle.

[0130] In the demodulation process of the receiver, the sampling point level information and the time slot level information are fully utilized, two-stage demodulation compensation including sampling point compensation and time slot compensation is used to improve the demodulation performance of the receiver, and the sensitivity of the whole communication system is improved.

[0131] Figure 12 A block diagram of a jitter compensation system of an optical communication receiver is shown for an exemplary embodiment of the present application. Figure 12 As shown in the figure, in an exemplary embodiment, the jitter compensation system of the optical communication receiver can be applied to a free space optical communication system using pulse modulation combined with a photon counting detector, and can include a sampling synchronization module, a sampling point compensation module, a down-sampling and deinterleaving module, a time slot compensation module and a decoding and decoding module, which are described in detail as follows.

[0132] The sampling synchronization module is used to sample and time slot synchronize the optical signal received by the photon counting detector to obtain a first signal; the sampling point compensation module is used to perform sampling point compensation processing on the first signal to obtain a second signal; the down-sampling and deinterleaving module is used to perform down-sampling, frame synchronization and deinterleaving processing on the second signal to obtain a third signal; the time slot compensation module is used to perform time slot compensation processing on the third signal to obtain a fourth signal; and the decoding and decoding module is used to perform signal demodulation and signal decoding on the fourth signal to recover the original information.

[0133] The two-stage compensation of the present embodiment compensates the detector jitter DJ and the time slot synchronization error SE respectively, so that the receiver has a large performance gain.

[0134] The present embodiment also provides a receiver which can be applied to a free space optical communication system using pulse modulation combined with a photon counting detector, and is used to implement the jitter compensation method of the optical communication receiver provided by any of the above embodiments.

[0135] The present embodiment also provides an optical communication system using pulse modulation combined with a photon counting detector, which can include the receiver provided by the above embodiments.

[0136] The two-stage compensation algorithm proposed by the present embodiment has been verified by simulation experiments to have a beneficial effect of improving the sensitivity of the receiver, and the specific verification process is as follows:

[0137] The present embodiment completes the simulation of the transmitter-channel-receiver three-module cascade, and the simulation experiment structure is as follows: Figure 13As shown, in the transmitter, a signal is generated by a signal source, and after channel coding, PPM modulation, interleaving and adding a frame header, the transmitted signal is transmitted to the receiver through a channel, and the photonic counting detector in the receiver receives the optical signal, and then through time slot synchronization, sampling point compensation, downsampling, frame synchronization, time slot compensation, deinterleaving, PPM demodulation and channel decoding processing, the original data is recovered, and the modules in the system are sequentially connected according to the signal flow direction. Through simulation experiment verification, the two-stage compensation algorithm provided in the embodiment of the application can make the sensitivity performance of the receiver obtain significant gain.

[0138] As Figure 14 shown, under the condition that the detector jitter coefficient DJ=0.2, the decoding threshold of the receiver of the algorithm (@BER=1e-6) is improved by more than 0.1dB than the method of using only the finite interval Poisson algorithm for time slot compensation; under the same signal intensity (@n s =3.7dB), the bit error rate is reduced by about 3 orders of magnitude (i.e. 1000 times) than the method of using only the finite interval Poisson algorithm for time slot compensation.

[0139] The embodiment of the application also provides a computer program product, which comprises computer instructions stored in a computer readable storage medium. A processor of a computer device reads the computer instructions from the computer readable storage medium, and the processor executes the computer instructions, so that the computer device executes the jitter compensation method of the optical communication receiver provided in the various optional embodiments.

[0140] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and units can refer to the corresponding processes in the foregoing method embodiments, which will not be described here.

[0141] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0142] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. According to actual needs, part or all of the units can be selected to achieve the purpose of the embodiment of the present application.

[0143] In addition, each function unit in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software function unit.

[0144] When the integrated unit is realized in the form of a software function unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application, essentially or in the form of a contribution to the prior art, or all or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in the embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0145] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of jitter compensation for an optical communication receiver, the method comprising: The method is applied to a free space optical communication system using pulse modulation combined with a photon counting detector, and the method comprises: sampling and time slot synchronization of an optical signal received by the photon counting detector to obtain a first signal; sampling point compensation processing of the first signal to obtain a second signal; the sampling point compensation processing of the first signal to obtain the second signal comprises: determining a time slot synchronization error of the photon counting detector and a probability density function thereof; determining a sampling point compensation coefficient according to the time slot synchronization error and the probability density function thereof; sampling point compensation processing of boundary sampling points according to the sampling point compensation coefficient to obtain the second signal; down-sampling, frame synchronization and de-interleaving processing of the second signal to obtain a third signal; time slot compensation processing of the third signal to obtain a fourth signal; signal demodulation and signal decoding of the fourth signal to recover original information.

2. The method of claim 1, wherein, the determination of the sampling point compensation coefficient according to the time slot synchronization error and the probability density function thereof comprises: determining a real start time and a real end time of a current time slot according to the time slot synchronization error; determining a real photon number of the current time slot according to the real start time, the real end time and observed photon numbers at different time instants; determining a mathematical expectation of the real photon number of the current time slot according to the time slot synchronization error and the probability density function thereof; taking a coefficient of a boundary sampling point in the mathematical expectation of the real photon number of the current time slot as the sampling point compensation coefficient.

3. The method of claim 2, wherein, the taking of the coefficient of the boundary sampling point in the mathematical expectation of the real photon number of the current time slot as the sampling point compensation coefficient comprises: taking coefficients of boundary sampling points in the current time slot in the mathematical expectation as compensation coefficients of the boundary sampling points at corresponding positions in the current time slot, and recording the compensation coefficients as a first compensation coefficient set; taking coefficients of boundary sampling points in adjacent time slots in the mathematical expectation as compensation coefficients of the boundary sampling points at corresponding positions in the adjacent time slots, and recording the compensation coefficients as a second compensation coefficient set.

4. The method of claim 3, wherein, the sampling point compensation processing of the boundary sampling points according to the sampling point compensation coefficient to obtain the second signal comprises: multiplying a photon number of a first boundary sampling point of the current time slot by a corresponding compensation coefficient in the first compensation coefficient set to obtain a first intermediate quantity for a current time slot boundary of the current time slot; multiplying a photon number of a second boundary sampling point of the adjacent time slot by a corresponding compensation coefficient in the second compensation coefficient set to obtain a second intermediate quantity; wherein a position of the second boundary sampling point is axially symmetrical to a position of the first boundary sampling point; taking a sum of the first intermediate quantity and the second intermediate quantity as a compensation photon number of the first boundary sampling point of the current time slot boundary of the current time slot; iterating all boundary sampling points of all time slots until the boundary sampling point compensation of all time slots is completed.

5. The method of claim 4, wherein, the number of the first boundary sampling point and the second boundary sampling point is one or more.

6. The method according to any one of claims 1 to 5, characterized in that, the time slot compensation processing of the third signal to obtain the fourth signal comprises: time slot compensation processing of the third signal based on a finite interval Poisson approximation method to obtain the fourth signal.

7. An optical communication receiver jitter compensation system, characterized by, The application discloses a jitter compensation method and system for an optical communication receiver. The sampling synchronization module is used for sampling and time slot synchronization of the optical signal received by the photon counting detector to obtain a first signal. The sampling point compensation module is used for sampling point compensation processing of the first signal to obtain a second signal. The down-sampling and deinterleaving module is used for down-sampling, frame synchronization and deinterleaving processing of the second signal to obtain a third signal. The time slot compensation module is used for time slot compensation processing of the third signal to obtain a fourth signal. The decoding module is used for signal demodulation and signal decoding of the fourth signal to recover original information.

8. A receiver, characterized by The application is applied to a free space optical communication system adopting pulse modulation combined with a photon counting detector, and is used for realizing the jitter compensation method of the optical communication receiver. The sampling synchronization module is used for sampling and time slot synchronization of the optical signal received by the photon counting detector to obtain a first signal. The sampling point compensation module is used for sampling point compensation processing of the first signal to obtain a second signal. The down-sampling and deinterleaving module is used for down-sampling, frame synchronization and deinterleaving processing of the second signal to obtain a third signal. The time slot compensation module is used for time slot compensation processing of the third signal to obtain a fourth signal. The decoding module is used for signal demodulation and signal decoding of the fourth signal to recover original information.

9. An optical communication system, characterized by The application adopts pulse modulation combined with a photon counting detector and comprises the receiver of claim 8.

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