Method and device for estimating cache demand of wireless optical communication ARQ (Automatic Repeat Request) system

Abstract

The invention relates to the technical field of wireless optical communication error control, and discloses a method for estimating the cache size requirement of an automatic repeat request (ARQ) system, which comprises the following steps of: (1) selecting a proper turbulence model, measuring an atmospheric turbulence refractive index structure constant, and calculating turbulence model parameters in combination with a communication wavelength; (2) establishing a detector output electric signal channel model, and calculating an outage probability and an error rate according to turbulence-related factors and system parameters; (3) respectively calculating the required cache size according to the outage probability and the bit error rate; and (4) calculating the size of the cache space by integrating the outage probability, the bit error rate, the communication rate and an ARQ feedback retransmission mechanism. According to the cache size estimation method based on the turbulence model and the output signal model, a theoretical basis is provided for cache estimation of wireless optical communication ARQ system design.

Description

Technical Field

[0001] The present invention relates to a method for estimating the size of an information cache space of an automatic retransmission request mechanism (ARQ) in the field of space optical communication, and in particular to a method for estimating the size of a required storage space within a period of time according to communication interruption and error probability caused by turbulence, which can ensure the needs without wasting resources and increasing the cost of the system. Background Art

[0002] With the rapid development of communication technology, wireless optical communication has attracted widespread attention as a high-speed, large-capacity communication method. However, in the actual application of wireless optical communication, atmospheric turbulence seriously affects the communication quality. Atmospheric turbulence can cause communication interruption and high bit error rate problems, which has become one of the key factors restricting the performance improvement of wireless optical communication systems.

[0003] Since atmospheric turbulence can cause burst errors, a single channel coding and interleaving technology cannot solve this long burst error problem, and a cache and automatic retransmission request (ARQ) mechanism must be used. The ARQ protocol ensures reliable data transmission by requesting the sender to resend the data when an error or lost data packet is detected at the receiving end. However, the effective operation of the ARQ mechanism depends on sufficient cache space. When communication is interrupted due to turbulence or the bit error rate is too high to communicate normally, the system needs to cache the information to be transmitted and wait for communication conditions to be restored before continuing to transmit.

[0004] At present, the existing technology has obvious deficiencies in estimating the cache requirements of wireless optical communication ARQ systems. Traditional methods often lack comprehensive consideration of the relationship between turbulence models, turbulence parameters and cache requirements, resulting in inaccurate cache size estimation. This inaccuracy may cause a series of problems. If the cache space is too small, the information to be transmitted may not be fully stored during communication interruptions or high bit error rates, resulting in data loss; if the cache space is too large, it will cause resource waste and increase system cost and complexity. To this end, the present invention solves the problem of accurately and efficiently estimating the cache requirements of wireless optical communication ARQ systems by providing a method for estimating the cache requirements of wireless optical communication ARQ systems, so as to optimize system performance and improve data transmission reliability and resource utilization. Summary of the invention

[0005] In view of the problem of communication interruption and high bit error rate caused by turbulence in space optical communication, the industry unanimously believes that the ARQ mechanism is a good way to resist turbulence. The ARQ protocol requires a large amount of cache so that when communication is interrupted or the bit error rate is very high and communication cannot be achieved, information is not sent but cached. The present invention provides an effective method to estimate the size of the cache to meet the needs of system design. The innovations are mainly in the following aspects:

[0006] (1) A quantitative relationship model is established between the cache size required by the ARQ system and the turbulence model, turbulence parameters, and the system information transmission rate in order to calculate the size of the cache space; the cache size of the system is estimated based on the statistical characteristics of the turbulence model (interruption probability, bit error rate) and the system designed information transmission rate, transmission power, etc.

[0007] (2) Based on the established model, optimize the relationship between information transmission rate, channel coding and signal power.

[0008] The technical solution adopted by the present invention is a method for estimating the buffer requirement size of a wireless optical communication ARQ system, and the specific estimation process includes the following steps:

[0009] Step 1, select a suitable turbulence model;

[0010] Step 2: Determine the refractive index structure constant of atmospheric turbulence

[0011] Step 3, according to the refractive index structure constant and the wavelength of the communication to calculate the model parameters of turbulence;

[0012] Step 4, establishing a channel model of the detector output electrical signal;

[0013] Step 5, calculating the communication interruption probability according to the turbulence model, turbulence parameters and system parameters of optical communication;

[0014] Step 6, calculating the buffer size required for the interruption according to the interruption probability caused by turbulence;

[0015] Step 7, calculating the communication bit error rate according to the channel model and the optical communication system parameters;

[0016] Step 8, calculating the storage size of the ARQ protocol buffer required according to the bit error rate;

[0017] Step 9: Calculate the size of the buffer space according to the interruption probability, bit error rate, communication rate, and ARQ feedback retransmission mechanism.

[0018] Furthermore, in the step of selecting a suitable turbulence model, the selection basis includes but is not limited to the characteristics of the communication environment and the turbulence intensity distribution information. The turbulence model of step 1 can select the logarithmic Weber model (EW), and turbulence causes light intensity flicker. The probability density (PDF) f(I) and distribution function (CDF) F(I) of the light intensity I are as follows:

[0019]

[0020] The parameters α and β are the shape parameters of the model, and η is the scale parameter.

[0021] Furthermore, the atmospheric turbulence refractive index structure constant in step 2 It can be measured by appropriate instruments, and the determination methods include the use of professional atmospheric optical measurement instruments or analytical calculation methods based on existing environmental data.

[0022] Furthermore, the channel model in step 3 considers the performance parameters of the detector, the optical signal transmission characteristics and the influence of turbulence on the signal; the turbulence parameters α, β and η can be obtained by the optical communication system parameters and the refractive index structure constant The calculation formula is as follows:

[0023]

[0024] Where D is the receiving aperture, is the refractive index structure constant, is the wave number, λ is the wavelength of the communication light wave, and L is the communication distance.

[0025]

[0026] in is the light intensity flicker index, and E[·] represents the mathematical expectation.

[0027]

[0028] where Γ(·) is the gamma function,

[0029] Furthermore, the calculation method of the output electrical signal model in step 4 is based on the combination of probability statistics theory and optical communication transmission theory, and can be expressed as:

[0030] y=ρIx+n

[0031] In binary on-off keying (OOK) modulation, x represents the baseband signal sent, that is, x is low or high (0 or 1); I is the input light intensity of the receiving detector; ρ represents the photoelectric conversion efficiency of the detector; n is the thermal noise generated by the system, which obeys a Gaussian distribution with a mean of 0 and a power of N0 / 2, and N0 represents the noise power; y represents the electrical signal output by the detector. The detector output signal-to-noise ratio can be expressed as

[0032] Furthermore, in step 5, according to the turbulence model, turbulence parameters and communication system parameters, the calculation process takes into account the expected value of communication data volume, data transmission rate and interruption duration, and the interruption probability P outage It can be calculated as follows:

[0033]

[0034] Where P() is the probability of an event occurring, and the interruption threshold represents the number of dB below the average irradiance, where, without loss of generality, the light intensity is normalized to the average value, i.e. =1. That is, the light intensity threshold

[0035] Furthermore, the cache size required to store the interrupt data in step 6 can be calculated as follows: Assuming the communication rate is r, within a period of time T, the required cache size is

[0036] M outage =rTP outage

[0037] The calculation takes into account the amount of communication data, the data transfer rate and the expected value of the interruption duration.

[0038] Furthermore, in step 7, the communication bit error rate P is calculated based on the channel model and the optical communication system parameters. e The method is as follows:

[0039]

[0040] where erfc(·) is the error complement function, f(I) is the probability density of the light intensity expressed in step 1, and SNR0 is the signal-to-noise ratio in the absence of turbulence, calculated as

[0041] SNR0=2ρP / N0

[0042] P is the optical power at the receiver, which can be estimated by system parameters. The above calculation method combines the effect of turbulence on optical signal modulation and channel coding characteristics.

[0043] Furthermore, the buffer storage size required due to bit errors in step 8 can be calculated as follows: Assume that the communication rate is r, the packet length is L bits, and the number of error bits in a period of time T is rTP e , then the maximum cache size required during this period is rTP e L bits, the average value is (1+rTP e )L / 2 bits. The calculation of cache storage size takes into account the ARQ protocol type, retransmission strategy, and error correction capability.

[0044] Furthermore, in step 9, based on the interruption probability, bit error rate, communication rate and ARQ feedback retransmission mechanism, the size of the buffer space is calculated to be M=rTP outage +rTP e L bits. The calculation comprehensively considers the situation where interruption and bit error occur simultaneously and the dynamic change of buffer demand under different ARQ feedback retransmission mechanisms.

[0045] The present invention also provides a device for estimating the cache requirements of a wireless optical communication ARQ system, including a processor and a memory, wherein the memory is used to store program instructions, and the processor is used to call the stored instructions in the memory to execute a method for estimating the cache requirements of a wireless optical communication ARQ system as described in the above technical solution.

[0046] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0047] 1. In view of the problem that the existing technology lacks a relatively accurate estimation method for the cache size required for the ARQ mechanism when dealing with the turbulence problem of space optical communication. The present invention establishes a quantitative relationship model between the cache space size and the turbulence model, turbulence parameters, channel model and communication system parameters, which can be used to more accurately calculate the cache size. This method avoids the drawbacks of insufficient cache leading to communication interruption and data loss or excessive cache wasting resources, ensures communication continuity and stability, optimizes resource allocation, and reduces system costs.

[0048] 2. The present invention derives the qualitative and quantitative relationship between the cache size and system parameters such as turbulence model parameters, interruption probability, channel model, bit error rate and communication rate. When calculating the cache required for the interruption, the interruption duration and the cache size caused by the interruption are estimated based on the interruption probability caused by turbulence combined with the communication rate and communication time to ensure that the data during the interruption period is completely stored; when calculating the error-related cache, the cache allocation is optimized based on the bit error rate, data packet length and communication duration. This method avoids the drawback of cache inaccuracy due to one-sided focus on a single factor, and ensures that cache resources are accurately adapted to needs in complex communications.

[0049] 3. The estimation method provided by the present invention is simple and effective, and does not occupy too much system computing overhead. The cache size can be adjusted dynamically according to the channel status, communication rate, etc., avoiding large-scale architecture adjustments that increase cost overhead, and providing a practical cache foundation for the robust and efficient operation of wireless optical communication ARQ systems in multiple scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A flow chart of a method for estimating buffer requirements of a wireless optical communication ARQ system provided by the present invention. DETAILED DESCRIPTION

[0051] The following will be combined with the accompanying drawings of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be clear that the embodiments described here are only a part of the many embodiments of the present invention, and do not cover all embodiments. Based on these embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should be included in the scope of protection of the present invention.

[0052] It should be particularly noted that, in the absence of any conflict, the various embodiments of the present invention and the various features in the embodiments can be used in combination with each other. The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments, but this explanation should not be regarded as a limitation to the present invention.

[0053] The present invention includes a method for estimating the buffer requirement size of a wireless optical communication ARQ system, such as Figure 1 As shown, the specific estimation process includes the following steps:

[0054] Step 1, select a suitable turbulence model;

[0055] Step 2: Determine the refractive index structure constant of atmospheric turbulence

[0056] Step 3, according to the refractive index structure constant and the wavelength of the communication to calculate the model parameters of turbulence;

[0057] Step 4, establishing a channel model of the detector output electrical signal;

[0058] Step 5, calculating the communication interruption probability according to the turbulence model, turbulence parameters and system parameters of optical communication;

[0059] Step 6, calculating the buffer size required for the interruption according to the interruption probability caused by turbulence;

[0060] Step 7, calculating the communication bit error rate according to the channel model and the optical communication system parameters;

[0061] Step 8, calculating the storage size of the ARQ protocol buffer required according to the bit error rate;

[0062] Step 9: Calculate the size of the buffer space according to the interruption probability, bit error rate, communication rate, and ARQ feedback retransmission mechanism.

[0063] Furthermore, the turbulence model in step 1 can be selected as the logarithmic Weber model (EW). Turbulence causes light intensity flickering, and the probability density (PDF) f(I) and distribution function (CDF) F(I) of the light intensity I are as follows:

[0064]

[0065] The parameters α and β are the shape parameters of the model, and η is the scale parameter.

[0066] Furthermore, the atmospheric turbulence refractive index structure constant in step 2 It can be measured by corresponding instruments.

[0067] Furthermore, the turbulence parameters α, β and η in step 3 can be obtained by the optical communication system parameters and the refractive index structure constant The calculation formula is as follows:

[0068]

[0069] Where D is the receiving aperture, is the refractive index structure constant, is the wave number, λ is the wavelength of the communication light wave, and L is the communication distance.

[0070]

[0071] in is the light intensity flicker index, where Γ(·) is the gamma function,

[0072]

[0073] Furthermore, the output electrical signal model in step 4 can be expressed as

[0074] y=ρIx+n

[0075] In binary on-off keying (OOK) modulation, x represents the baseband signal sent, that is, x is low or high (0 or 1); I is the input light intensity of the receiving detector; ρ represents the photoelectric conversion efficiency of the detector; n is the thermal noise generated by the system, which obeys a Gaussian distribution with a mean of 0 and a power of N0 / 2; y represents the electrical signal output by the detector. The detector output signal-to-noise ratio can be expressed as

[0076] Furthermore, in step 5, according to the turbulence model, turbulence parameters and communication system parameters, the interruption probability P outage It can be calculated as follows

[0077]

[0078] Where P() is the probability of an event occurring, and the interruption threshold represents the number of dB below the average irradiance, where, without loss of generality, the light intensity is normalized to the average value, i.e. =1.

[0079] Light intensity threshold

[0080] Furthermore, the buffer size required for storing the interrupt data in step 6 can be calculated as follows: Assuming the communication rate is r, within a period of time T, the required buffer size is:

[0081] M outage =rTP outage

[0082] Furthermore, in step 7, the communication bit error rate P is calculated based on the channel model and the optical communication system parameters. e The method is as follows:

[0083]

[0084] where erfc(·) is the error complement function, f(I) is the probability density of the light intensity expressed by formula (1) in step 1, and SNR0 is the signal-to-noise ratio in the absence of turbulence, calculated as:

[0085] SNR0=2ρP / N0

[0086] P is the optical power at the receiver, which can be estimated from the system parameters.

[0087] Furthermore, the buffer size required due to bit errors in step 8 can be calculated as follows: Assume that the communication rate is r, the packet length is L bits, and the number of error bits in a period of time T is rTP e , then the maximum cache size required during this period is rTP e L bits, the average value is (1+rTP e )L / 2 bits.

[0088] Furthermore, in step 9, based on the interruption probability, bit error rate, communication rate and ARQ feedback retransmission mechanism, the size of the buffer space is calculated to be M=rTP outage +rTP e L bits.

[0089] Example 1: Cache requirement estimation based on weak turbulence model

[0090] The parameters of the wireless optical communication system used in this embodiment are as shown in the parameter table of embodiment 1:

[0091] Table 1: Parameters of Example 1

[0092]

[0093] The working wavelength is λ=780nm, the communication distance is L=1km, the communication rate is r=1Gbps, the receiving aperture is D=100mm, and the interruption threshold is F T =1dB, turbulent refractive index structure constant The packet length is l n =12000bit. Under the above parameters, the specific calculation steps for the required cache size are as follows:

[0094] Step 1, select the turbulence model;

[0095] In this embodiment, the logarithmic Weber (EW) model is selected as the turbulence model. This model has a clear description of the probability density function (PDF) and cumulative distribution function (CDF) of light intensity flicker, and is applicable to weak turbulence conditions as follows: Turbulence causes light intensity flicker, and the probability density (PDF) f(I) and distribution function (CDF) F(I) of light intensity I are

[0096]

[0097] The parameters α and β are the shape parameters of the model, and η is the scale parameter.

[0098] Step 2: Determine the turbulent refractive index structure constant

[0099] The turbulent refractive index structure constant is measured by a known instrument and is set to

[0100]

[0101] Step 3, calculating the shape parameters α and β and the scale parameter η of the turbulence;

[0102] According to the turbulence model and communication system parameters, the shape parameters α and β of the turbulence and the scale parameter η are calculated. The formula is as follows:

[0103]

[0104]

[0105] Where D is the receiving aperture, is the refractive index structure constant, is the wave number, λ is the wavelength of the communication light wave, and L is the communication distance. is the light intensity flicker index, where Γ(·) is the gamma function,

[0106] According to the parameters in the parameter table of Example 1, the wavelength is λ=780nm, the distance is L=1km, the receiving aperture is D=100mm, and the turbulent refractive index structure constant is According to the model and experience, the values ​​are:

[0107] α≈1.84

[0108] β≈7.11

[0109] η≈0.99

[0110] Step 4, establishing a channel model;

[0111] In the binary on-off keying (OOK) modulation system, the output electrical signal y at the receiving end is expressed as:

[0112] y=ρIx+n

[0113] Where x represents the baseband signal sent, I is the input light intensity of the receiving detector; ρ represents the photoelectric conversion efficiency of the detector; n is the thermal noise generated by the system, which obeys a Gaussian distribution with a mean of 0 and a power of N0 / 2; the detector output signal-to-noise ratio can be expressed as

[0114] Step 5, calculate the interruption probability; according to the turbulence model, turbulence parameters and communication system parameters, the interruption probability P outage It can be calculated as follows:

[0115]

[0116] Where P() is the probability of an event occurring, and the interruption threshold represents the number of dB below the average irradiance, where, without loss of generality, the light intensity is normalized to the average value, i.e. =1.

[0117] Light intensity threshold

[0118] Substitute the parameters in the parameter table of Example 1 into the equation, and when F T =1dB, α≈1.84, β≈7.11, η≈0.99

[0119]

[0120] Step 6, calculate the interruption buffer size; calculate the buffer size required for the interruption according to the interruption probability caused by turbulence; the buffer size required to store the interruption data can be calculated as follows: assuming that the communication rate is r, within a period of time T, the required buffer size is

[0121] M outage =rTP outage

[0122] The communication rate is r = 1Gbps, the interruption time is T = 1s, and the interruption probability is P outage ≈0.0464Calculated: M outage ≈1×10 9 ×1×0.0464bit≈5.8MB.

[0123] Step 7, calculate the bit error rate and the size of the bit error buffer; calculate the communication bit error rate P according to the channel model and the optical communication system parameters e The method is as follows:

[0124]

[0125] where erfc(·) is the error complement function, f(I) is the probability density of the light intensity expressed in step 1, and SNR0 is the signal-to-noise ratio in the absence of turbulence, calculated as

[0126] SNR0=2ρP / N0

[0127] P is the optical power at the receiver, which can be estimated from the system parameters.

[0128] According to the model and empirical values, when SNR0 = 10dB, the bit error rate P e =4.3×10 -5

[0129] Step 8, comprehensively calculate the required buffer size; calculate the storage size of the buffer required by the ARQ protocol based on the bit error rate; the buffer size required for the bit error can be calculated as follows: Assume that the communication rate is r and the packet length is l n bits, within a period of time T, the number of error bits is rTP e , then the maximum cache size required during this period is rTP e l n bits, the average value is (1+rTP e ) n / 2 bits.

[0130] According to the parameters in the parameter table of Example 1, the length of the data packet is l n = 12000 bits, the maximum buffer size required is rTP e l n =1×10 9 ×1×4.3×10 -5 ×12000bit≈64.5MB, the average value is

[0131] Step 9, calculating the size of the buffer space according to the interruption probability, bit error rate, communication rate and ARQ feedback retransmission mechanism; according to the parameters in the parameter table of embodiment 1, the size of the buffer space is calculated according to the interruption probability, bit error rate, communication rate and ARQ feedback retransmission mechanism:

[0132] M=rTP outage +rTP e l n ≈5.8MB+64.5MB=70.3MB

[0133] In a conventional wireless optical communication ARQ system, the cache size is the size of all data segments, i.e., rT. The estimation method provided by the present invention calculates the size of the cache space as rTP outage +rTP e l n Compared with traditional caching methods, times cache optimization gain, where It is related to the turbulence model, turbulence parameters, and communication system parameters. The cache optimization gain value is greater than 1 based on the empirical value.

[0134] On the other hand, an embodiment of the present invention also provides a device for estimating the cache requirements of a wireless optical communication ARQ system, including a processor and a memory, wherein the memory is used to store program instructions, and the processor is used to call the stored instructions in the memory to execute a method for estimating the cache requirements of a wireless optical communication ARQ system as described in the above technical solution.

[0135] In summary, the above specific embodiments are only implementation cases of the present invention under specific conditions and are not intended to limit the protection scope of the present invention. As long as the spirit and principles of the present invention are followed, any modification, equivalent replacement, improvement and other operations performed should be included in the protection scope of the present invention.

Claims

1. A method for estimating buffer requirements of a wireless optical communication ARQ system, characterized in that: The following steps are involved: Step 1, select a suitable turbulence model; Step 2: Determine the refractive index structure constant of atmospheric turbulence Step 3, according to the refractive index structure constant and the wavelength of the communication to calculate the turbulence model parameters; Step 4, establishing a channel model of the detector output electrical signal; Step 5, calculating the communication interruption probability according to the turbulence model, the turbulence model parameters and the system parameters of the optical communication; Step 6, calculating the buffer size required for the interruption according to the interruption probability caused by turbulence; Step 7, calculating the communication bit error rate according to the channel model and the optical communication system parameters; Step 8, calculating the storage size of the ARQ protocol buffer required according to the bit error rate; Step 9: Calculate the size of the buffer space according to the interruption probability, bit error rate, communication rate, and ARQ feedback retransmission mechanism.

2. The method for estimating buffer requirements of a wireless optical communication ARQ system according to claim 1, characterized in that: In step 1, the turbulence model is selected as the logarithmic Weber model according to the characteristics of the communication environment and the turbulence intensity distribution information. Turbulence causes light intensity flickering. The probability density f(I) and distribution function F(I) of the light intensity I are as follows: The parameters α and β are the shape parameters of the model, and η is the scale parameter.

3. The method for estimating buffer requirements of a wireless optical communication ARQ system according to claim 1, characterized in that: The turbulence model parameters in step 3 include the shape parameters α, β and scale parameter η of the model, which are obtained by the optical communication system parameters and the refractive index structure constant The calculation formula is as follows: Where D is the receiving aperture, is the refractive index structure constant, is the wave number, λ is the wavelength of the communication light wave, and L is the communication distance; in is the light intensity flicker index, I is the light intensity, and E[·] represents the mathematical expectation; where Γ(·) is the gamma function, 4. The method for estimating buffer requirements of a wireless optical communication ARQ system according to claim 1, characterized in that: The channel model of the output electrical signal in step 4 is affected by the performance parameters of the detector, the transmission characteristics of the optical signal, and the influence of turbulence on the signal, and is expressed as: y=ρIx+n In binary on-off keying modulation, x represents the transmitted baseband signal, I is the input light intensity of the receiving detector; ρ represents the photoelectric conversion efficiency of the detector; n is the thermal noise generated by the system, which obeys a Gaussian distribution with a mean of 0 and a power of N0 / 2, and N0 represents the noise power; y represents the electrical signal output by the detector; the detector output signal-to-noise ratio is expressed as 5. The method for estimating buffer requirements of a wireless optical communication ARQ system according to claim 1, characterized in that: In step 5, the interruption probability P is calculated based on the turbulence model, turbulence model parameters and communication system parameters based on the combination of probability statistics theory and optical communication transmission theory. outage , the calculation formula is as follows: Among them, P() is the probability of an event occurring, and the interruption threshold represents the number of dB below the average irradiance, and I is the light intensity, where, without loss of generality, the light intensity data are normalized to the average value, i.e. =1, light intensity threshold α and β are the shape parameters of the turbulence model, and η is the scale parameter.

6. The method for estimating buffer requirements of a wireless optical communication ARQ system according to claim 1, characterized in that: In step 6, the cache size is calculated based on the communication data volume, data transmission rate, and expected value of the interruption duration. Assuming the communication rate is r, the required cache size within a period of time T is: M outage =rTP outage 。 P outage is the interruption probability.

7. The method for estimating buffer requirements of a wireless optical communication ARQ system according to claim 1, characterized in that: In step 7, the communication bit error rate P is calculated based on the channel model and the optical communication system parameters. e The method is as follows: Where erfc(·) is the error complement function, f(I) is the light intensity, the probability density of , and SNR0 is the signal-to-noise ratio in the absence of turbulence. The calculation formula is: SNR0=2ρP / N0 P is the optical power of the receiver, estimated by the system parameters, and N0 represents the noise power.

8. The method for estimating buffer requirements of a wireless optical communication ARQ system according to claim 1, characterized in that: The buffer storage size required due to bit errors in step 8 is calculated as follows: Assume that the communication rate is r, the packet length is L bits, and the number of error bits in a period of time T is rTP e , then the maximum cache size required during this period is rTP e L bits, the average value is (1+rTP e )L / 2 bits.

9. The method for estimating buffer requirements of a wireless optical communication ARQ system according to claim 1, characterized in that: In step 9, the size of the buffer space is calculated as M = rTP based on the interruption probability, bit error rate, communication rate and ARQ feedback retransmission mechanism. outage +rTP e L bits.

10. A device for estimating buffer requirements of a wireless optical communication ARQ system, characterized in that: It comprises a processor and a memory, the memory is used to store program instructions, and the processor is used to call the stored instructions in the memory to execute a method for estimating the buffer demand of a wireless optical communication ARQ system as claimed in any one of claims 1 to 9.

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