CN104753829B - Dimming method and dimming device - Google Patents

Abstract

The invention discloses a kind of light-dimming method and dimming devices, which comprises in medium access control (MAC) layer, divides the sub- MSDU that MAC data service unit (MSDU) is multiple equal lengths；Sub- MSDU after segmentation is encapsulated into respectively in Medium Access Control (MAC) Protocol Data Unit independent (MPDU), and is respectively that each MPDU generates compensation frame (CF) according to the target brightness value of light source；It polymerize the MPDU and CF and is the physical layer service data (PSDU) of physical layer protocol data unit (PPDU), and transmits the PPDU.

Description

Dimming method and dimming device

technical field

The invention relates to a dimming technology in the field of optical communication, in particular to a dimming method and a dimming device.

Background technique

Visible light communication (VLC, Visible Light Communication) technology refers to the technology of short-distance optical wireless communication using an optical medium with a wavelength in the range of 400 nanometers (nm) to 700 nm that is visible to the naked eye. The VLC technology has the advantages of being free from electromagnetic interference, and there is no interference related to radio frequency (RF, Radio Frequency) systems, and the spectrum range it uses is an unlicensed spectrum (Unlicensed Spectrum). When using visible light for data transmission, at the sending end, the visible light source (such as a light-emitting diode) can be turned on and off quickly or the brightness of the visible light source can be modulated; at the receiving end, after receiving the modulated optical signal, it is converted to Data that can be processed by the receiver.

When using visible light for communication, it must first ensure that the normal use of lighting equipment by users is not affected while realizing data transmission. This needs to consider the following two issues: one is to realize the data transmission function; the other is to support the adjustment of the brightness of the light source (Dimming) under the premise of ensuring that the light source does not flicker.

In the prior art, there are mainly two ways of dimming:

1) In the idle/receiving state, the sender uses the idle pattern (idle pattern), that is, realizes dimming by independently sending frames for adjusting the brightness, but this method lacks a specific implementation plan for realizing the dimming function;

2) At the physical layer, the idle mode closely related to the modulation method and channel coding scheme is used for dimming. This method can only adjust the brightness of the light source with a predetermined range, but cannot smoothly adjust the brightness of the light source, and the dimming is flexible. Not enough.

Contents of the invention

In view of this, the embodiments of the present invention provide a dimming method and a dimming device, which ensure no flickering of a light source while realizing a communication function, and realize flexible dimming in a visible light communication system according to user requirements.

In order to achieve the above object, the technical solution of the embodiment of the present invention is achieved in this way:

An embodiment of the present invention provides a dimming method, the method comprising:

At the media access control (MAC, Media Access Control) layer, split the MAC data service unit (MSDU, MAC Service Data Unit) into multiple sub-MSDUs of equal length;

Encapsulate the divided sub-MSDUs into independent MAC protocol data units (MPDU, MAC ProtocolData Unit), and generate compensation frames (CF, CompensatoryFrame) for each MPDU according to the target brightness value of the light source;

Aggregating the MPDU and the CF into a physical-layer service data unit (PSDU, Physical-layer Service Data Unit) in a physical-layer protocol data unit (PPDU, Physical-layer Protocol Data Unit), and transmitting the PPDU.

An embodiment of the present invention also provides a dimming device, the dimming device comprising:

The segmentation unit is used to segment the MSDU into multiple sub-MSDUs of equal length at the MAC layer;

a compensation unit, configured to encapsulate the divided sub-MSDUs into respective independent MPDUs, and generate CF for each MPDU according to the target brightness value of the light source;

an aggregation unit, configured to aggregate the MPDU and the PSDU in which the CF is a PPDU;

An optical drive unit, configured to transmit the PPDU.

In the embodiment of the present invention, the adopted dimming technical solution is independent of the modulation mode and channel coding scheme adopted during data transmission, and can realize flexible dimming for the optical communication system according to user requirements.

Description of drawings

Fig. 1 is a schematic diagram of the implementation flow of the dimming method in the embodiment of the present invention;

Fig. 2 is a schematic diagram of the second implementation flow of the dimming method in the embodiment of the present invention;

FIG. 3 is a schematic diagram of a frame structure of the MAC layer and the physical layer of the IEEE802.15.7 standard;

FIG. 4 is a schematic structural diagram of a PPDU in an embodiment of the present invention;

Figure 5 is a schematic diagram of the color/visible/dimming (CVD, Color Visible Dimming) frame structure in the IEEE802.15.7 standard;

Fig. 6 is a schematic diagram of the composition and structure of the dimming device in the embodiment of the present invention.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

As shown in Figure 1, the dimming method recorded in the embodiment of the present invention includes the following steps:

Step 101 , at a media access control (MAC, Media Access Control) layer, divide a MAC data service unit (MSDU, MAC Service Data Unit) into multiple sub-MSDUs of equal length.

Step 102: Encapsulate each divided sub-MSDU into a mutually independent MAC protocol data unit (MPDU, MAC Protocol Data Unit), and generate a compensation frame (CF, CF) for the MPDU according to the target value of the light source brightness. Compensatory Frame).

Step 103, aggregate and generate a physical-layer service data unit (PSDU, Physical-layer Service Data Unit) in a physical-layer protocol data unit (PPDU, Physical-layer Protocol Data Unit) according to the MPDU and the CF corresponding to the MPDU .

Step 104, transmit the generated PPDU.

In one embodiment, before the MAC layer divides the MSDU into multiple sub-MSDUs of equal length, the method further includes:

Determine that the length of the MSDU is less than or equal to the difference between the maximum data length, the physical layer overhead length, and the MAC layer overhead length in turn.

In one embodiment, the maximum data length is a product of a period T and a data rate of the link, and the period T is an inverse of a critical flicker fusion frequency (CFF, Critical Flicker Frequency).

In one embodiment, when it is determined that the length of the MSDU is greater than the difference between the maximum data length, the physical layer overhead length, and the MAC layer overhead length, the method further includes:

Re-dividing the MSDU into multiple sub-MSDUs of equal length until it is determined that the length of the obtained sub-MSDU is less than or equal to the difference between the maximum data length and the physical layer overhead length and the MAC layer overhead length.

In one embodiment, the generating CF for each MPDU according to the target brightness value of the light source includes:

When it is determined that the actual luminance value of the light source is different from the target luminance value of the light source, CF is generated for each MPDU according to the target luminance value of the light source.

In one embodiment, when determining that the actual luminance value of the light source is different from the target luminance value of the light source, generating a CF for each MPDU according to the target luminance value of the light source, including:

The length n _CF of the sequence of the data part (CFD, Compensatory Frame Data) of the CF is determined according to the following formula:

Among them, α represents the target brightness value of the light source, n _cost represents the number of "1" in the overhead cost part, n _MSDU represents the number of "1" in MSDU, n _CF represents the number of "1" in CFD; size _cost Indicates the length of the cost part, size _MSDU indicates the length of the MSDU, and size _CF indicates the length of the CF; the cost includes the MAC layer header (MHR, MAC-layerHeadeR) field, the MAC layer tail field, and the physical layer Preamble field, physical layer header field, CF header field and padding (Pad) field.

In one embodiment, when it is determined that the actual luminance value of the light source is the same as the target luminance value of the light source, the method further includes: encapsulating the divided sub-MSDUs into respective independent MPDUs;

The MPDU is used as the PSDU part of the PPDU, and the PPDU is transmitted.

That is, the MPDU is encapsulated as the data part of the PPDU, and the PPDU encapsulated with the MPDU is transmitted.

In one embodiment, after the aggregation of the MPDU and the PSDU in which the CF is a PPDU, the method further includes:

It is determined that the aggregated length of the PSDU is less than or equal to the difference between the maximum data length and the physical layer overhead length.

In one embodiment, when the length of the PSDU obtained by determining the aggregation is greater than the difference between the maximum data length and the physical layer overhead length, the method further includes:

Re-dividing the MSDU into multiple sub-MSDUs of equal length until the aggregated PSDU is less than or equal to the maximum data length and physical layer overhead length based on the obtained sub-MSDUs and the CF generated corresponding to the MSDUs difference.

When the aggregated length of the PSDU is less than or equal to the difference between the maximum data length and the physical layer overhead length, it means that during data transmission, there will be no light source flickering problem that users can feel.

The dimming method provided by the embodiment of the present invention will be further described in detail below. FIG. 2 is a schematic diagram of the second implementation flow of the dimming method in the embodiment of the present invention. As shown in FIG. 2 , it includes the following steps:

Step 201, determine that the data unit of the Logical Link Control (LLC, Logical Link Control) sublayer enters the MAC layer and becomes the data part MSDU of the MPDU.

That is, when the data unit of the LLC sublayer enters the MAC layer and becomes the data part MSDU of the MPDU, step 202 is executed.

As shown in FIG. 3 , the MPDU transmitted at the MAC layer includes an MSDU as a data part, a MAC header and a Frame Check Sequence (FCS, Frame Check Sequence).

Step 202, judging whether the length of the MSDU is smaller than the difference between the maximum data length, the physical layer overhead length, and the MAC layer overhead length, if yes, execute step 203, otherwise, execute step 210.

The difference between the maximum data length and the physical layer overhead length and the MAC layer overhead length refers to the difference obtained by sequentially subtracting the physical layer overhead length and the MAC layer overhead length from the maximum data length.

The maximum data length refers to the maximum data length that can be transmitted by the sending end of the visible light communication within the period T, which is set to size _max , and the value of size _max is as shown in formula (1):

size _max = T × data_rate (1)

In formula (1), T is the reciprocal of CFF, data_rate is the data rate of the link; flicker critical fusion frequency is the lowest repetition frequency that does not cause flicker sensation;

The physical layer overhead length refers to the sum of the synchronization header (SHR, Synchronization Header) field length and the PHR field length, and the MAC layer overhead length refers to the sum of the MHR field length and the MAC layer tail field, that is, the FCS field.

Step 203, judging whether the actual luminance value of the light source is equal to the target luminance value of the light source, if they are equal, perform step 204; otherwise, perform step 205.

Step 204, transmit the PPDU.

The MPDU in step 201 is used as the data part of the PPDU, that is, the PSDU is encapsulated into the PPDU transmitted at the physical layer, and the PPDU is transmitted.

In step 203, when the actual luminance value of the light source is equal to the target luminance value of the light source, there is no need to adjust the luminance value of the light source. Therefore, when step 204 is executed, as shown in FIG. 3 , the MPDU in step 201 is used as the PPDU The data part (that is, PSDU) is encapsulated into the PPDU transmitted at the physical layer, and the PPDU also includes a preamble and a physical layer header.

Step 205, determine the length of the aggregated MPDU (A-MPDU, Aggregated-MPDU) generated according to the aggregation of the MSDU and the CF.

The compensation frame is aggregated with the data frame MSDU to generate a schematic diagram of the structure of the A-MPDU as shown in Figure 4. The A-MPDU is encapsulated into the data part of the PPDU (ie PSDU) for transmission, and the MPDU (1) and the corresponding CF ( 1) The data part aggregated into PPDU (1), namely PSDU (1), MPDU (2) and the corresponding CF (2) are aggregated into the data part of PPDU (1), namely PSDU (2), PPDU (1), PPDU (2) includes the corresponding synchronization header (SHR, Synchronization Header) field, physical layer header (PHR, Physical-layer HeadR) field; MPDU (1) and MPDU (2) include the corresponding MHR field, FCS field and Fill (Pad) field.

CFD in CF is used to adjust the brightness of the light source. When the actual brightness value of the light source is less than the target brightness value of the light source, the compensation frame CF is used to increase the brightness of the light source. At this time, CFD is a sequence of all "1", and the number of "1" It is represented by n _CF ; when the actual brightness value of the light source is greater than the target brightness value of the light source, the compensation frame CF is used to lower the brightness of the light source. At this time, the compensation frame data part CFD is a sequence of all "0", and the number of "0" is represented by n _CF Represents; the relationship between n _CF and the target brightness value of the light source is shown in formula (2):

In the formula (2), the parameter α represents the target brightness target value of the light source, the parameter n _cost represents the number of "1" in the overhead (cost) part, n _MSDU represents the number of "1" in the MSDU, and n _CF represents the compensation frame The number of "1" in the CFD of the data part; the cost indicates the overhead other than valid data, including the MHR field, the MAC layer tail field SHR field, the physical layer header field, the CF header field and the Pad field; the size _cost indicates The length of the cost part, size _MSDU represents the length of MSDU, and size _CF represents the length of CF; the Pad is used to align 32-bit word boundaries, and is composed of "0" and "1"sequences; since the light source in this embodiment The adjustment of brightness is realized through "1" or "0" sequences of different lengths. Therefore, it supports smooth adjustment of the brightness of the corresponding light source, that is, the range of each adjustment can be set according to actual needs.

The CF used for dimming in the embodiment of the present invention can adopt the color/visible/dimming (CVD, Color Visible Dimming) frame format in the IEEE802.15.7 standard, as shown in Figure 5, the MHR field contains the control information of the CVD frame , the FCS field contains the checking information of the MACMHR, and the data part field contains the data content of the CVD frame. Compared with Figure 4, the MHR field and the FCS field of the CVD frame constitute the header of the CF (CFH, CF, Compensatory Frame Header), and the data part field of the CVD frame corresponds to the data part of the CF, that is, CFD.

The determination of CFD in CF can be realized by presetting all "1" and all "0" sequences of different lengths. When generating CF, it is sufficient to directly assign a preset sequence of corresponding length to the compensation frame. If the length of the sequence does not match the length of the determined compensation frame, the preset sequence can be combined to obtain the determined data part of the compensation frame. For example: all "1" sequences with a length of 100 bits, 200 bits and 400 bits are pre-set. When generating compensation frames, in addition to generating CFs with CFD lengths of 100 bits, 200 bits and 400 bits, you can also generate CFD CF with a length of 300 bits (ie 100 bits plus 200 bits), 500 bits (ie 100 bits plus 400 bits), 600 bits (ie 200 bits plus 400 bits) and 700 bits (ie 100 bits plus 200 bits plus 400 bits) All "1" sequences.

Step 206, judging whether the length of the A-MPDU is smaller than the difference between the maximum data length and the physical layer overhead length, if yes, execute step 209; otherwise, execute step 207.

In practical applications, the compensation frame length size _CF calculated by formula (2) also needs to satisfy the following formula:

size _cost + size _MSDU + size _CF ≤ size _max (3)

Formula (3) defines the maximum data length that can be transmitted each time when the compensation frame CF dimming is used. If the formula (3) is not satisfied, there will be a flickering problem of the light source that the user can feel when transmitting the PPDU. This shows that when the length of the A-MPDU is greater than the difference between the maximum data length size _MSDU and the physical layer overhead length n _cost , the length of the MSDU or sub-MSDU is too large, and it is necessary to split the MSDU or re-segment the MSDU into sub-MSDUs with shorter lengths. MSDU.

Step 207, dividing the MSDU into multiple sub-MSDUs of equal length.

Step 208, judging whether the length of the sub-MSDU is smaller than the difference between the maximum data length, the physical layer overhead length, and the MAC layer overhead length, if yes, execute step 205; otherwise, execute step 207.

When the judgment result of step 208 is No, when step 207 is re-executed, the length of the sub-MSDU obtained by dividing the MSDU is shorter than the length of the sub-MSDU obtained by dividing the MSDU in the previous time, that is, when step 207 is executed for the m time, the division of the MSDU is t _m sub-MSDUs of equal length, when step 207 is executed for the nth time, the MSDU is divided into t _n sub-MSDUs of equal length, and when m is smaller than n, t _n is greater than t _m .

Step 209, transmit the PPDU.

After the last execution of step 207, the sub-MSDUs obtained are encapsulated into separate MPDUs respectively, and compensation frames are generated for each MPDU respectively; the aggregation MPDU and the compensation frame are A-MPDU, and the A-MPDU is used as the data part of the PPDU ( ie PSDU), and transmit PPDU.

For example, after the MSDU in step 201 is divided into MSDU (1) and MSDU (2) shown in Figure 4, and the length of the A-MPDU aggregated and generated in step 20 is smaller than the difference between the maximum data length and the physical layer overhead length , then in this step, the PPDU (1) and PPDU (2) shown in Figure 4 are transmitted.

When in step 206, the length of the A-MPDU is greater than the difference between the maximum data length size _MSDU and the physical layer overhead length n _cost , it means that during data transmission, there will be no light source flickering problem that the user can feel, thus, step 209 , encapsulate the A-MPDU into the data part of the PPDU (that is, the PSDU), and transmit the PPDU.

Step 210, dividing the MSDU into multiple sub-MSDUs of equal length.

Step 211, determine whether the length of the sub-MSDU is smaller than the difference between the maximum data length, the physical layer overhead length, and the MAC layer overhead length, if yes, execute step 212; otherwise, execute step 210.

When the judgment result of step 211 is no, when step 210 is re-executed, the length of the sub-MSDU obtained by dividing the MSDU is shorter than the length of the sub-MSDU obtained by the previous division of the MSDU, that is, when step 210 is executed for the m time, the division of the MSDU is t _m sub-MSDUs of equal length, when step 210 is executed for the nth time, the MSDU is divided into t _n sub-MSDUs of equal length, and when m is smaller than n, t _n is greater than t _m .

Step 212, judging whether the actual luminance value of the light source is equal to the target luminance value of the light source, if they are equal, perform step 213; otherwise, perform step 214.

Step 213, transmit the PPDU.

When the actual luminance value of the light source is equal to the target luminance value of the light source, there is no need to adjust the luminance value of the light source. Therefore, the sub-MSDUs obtained in the last execution of step 210 are respectively encapsulated into independent MPDUs, and there is no need to generate Compensation frame; use the encapsulated MPDU as the PSDU part of the PPDU, and transmit the PPDU.

Step 214, determine the length of the A-MPDU generated according to the aggregation of the MSDU and the CF.

Step 215, judge whether the length of the A-MPDU is smaller than the difference between the maximum data length and the physical layer overhead length, if yes, execute step 216; otherwise, execute step 217.

When the length of the A-MPDU is less than the difference between the maximum data length and the physical layer overhead length, it means that when the A-MPDU is used as the data part of the PPDU and the PSDU is transmitted, there will be no light source flickering problem that can be detected by human eyes.

Step 216, transmit the PPDU.

The A-MPDU is used as the data part of the PPDU (that is, the PSDU), and the PPDU is transmitted.

Step 217, divide the MSDU into multiple sub-MSDUs of equal length, and execute step 215.

The length of the MSDU obtained by splitting the MSDU in step 217 is less than the length of the MSDU obtained by splitting the MSDU before step 217, and when step 217 is repeatedly executed, the length of the sub-MSDU obtained by executing step 217 each time is smaller than the previous When step 217 is executed, the length of the obtained sub-MSDU until the obtained sub-MSDU is aggregated with the corresponding CF to obtain an A-MPDU, the length of the A-MPDU is less than the difference between the maximum data length and the physical layer overhead length, to ensure When the A-MPDU is transmitted as the data part of the PPDU (that is, the PSDU), the light source does not flicker.

The embodiment of the present invention also records a computer-readable medium, where computer-executable instructions are stored in the computer-readable medium, and the computer-executable instructions are used to execute the dimming method shown in FIG. 1 , or execute the dimming method shown in FIG. 2 dimming method shown.

FIG. 6 is a schematic structural diagram of a dimming device in an embodiment of the present invention. The dimming device can be set in the transmitting end of the visible light communication system, or can be set in a device independent of the transmitting end, as shown in FIG. 6 , The dimming device includes:

The segmentation unit 10 is used to segment the MSDU into multiple sub-MSDUs of equal length at the MAC layer;

The compensation unit 20 is configured to encapsulate the divided sub-MSDUs into respective independent MPDUs, and generate CF for each MPDU according to the target brightness value of the light source;

An aggregation unit 30, configured to aggregate the MPDU and the PSDU in which the CF is a PPDU;

The optical drive unit 40 is configured to transmit the PPDU.

Wherein, the dimming device also includes:

The determination unit 50 is configured to trigger the segmentation unit 10 when it is determined that the length of the MSDU is less than or equal to the difference between the maximum data length and the physical layer overhead length and the MAC layer overhead length.

Wherein, the maximum data length is the product of the period T and the data rate of the link, and the period T is the reciprocal of CFF.

Wherein, the determining unit 50 is further configured to trigger the segmentation unit 10 to re-segment the MSDU when it is determined that the length of the MSDU is greater than the difference between the maximum data length, the physical layer overhead length, and the MAC layer overhead length in turn Be a plurality of sub-MSDUs of equal length until it is determined that the length of the obtained sub-MSDU is less than or equal to the difference between the maximum data length and the physical layer overhead length and the MAC layer overhead length in turn;

The segmentation unit 10 is further configured to re-segment the MSDU into multiple sub-MSDUs of equal length.

Wherein, the compensation unit 20 is further configured to generate CF for each MPDU according to the target brightness value of the light source when determining that the actual brightness value of the light source is different from the target brightness value of the light source.

Wherein, the compensation unit 20 is further configured to determine the length n _CF of the sequence of the data part CFD of the CF according to the following formula:

Among them, α represents the target brightness value of the light source, n _cost represents the number of "1" in the cost part, n _MSDU represents the number of "1" in the MSDU, n _CF represents the number of "1" in the CFD; size _cost represents The length of the cost part, size _MSDU indicates the length of the MSDU, size _CF indicates the length of the CF; the cost includes the MHR field, the tail field of the MAC layer, the physical layer preamble field, the physical layer header field, the CF The header field and Pad field.

Wherein, the dimming device also includes:

Encapsulation unit 60, configured to encapsulate the divided sub-MSDUs into respective independent MPDUs when the compensation unit 20 determines that the actual luminance value of the light source is the same as the target luminance value of the light source;

The optical drive unit 40 is further configured to use the MPDU as a PSDU part of a PPDU and transmit the PPDU.

Wherein, the determining unit 50 is further configured to determine that the length of the aggregated PSDU is less than or equal to the maximum data length and the physical layer The difference in overhead length.

Wherein, the determining unit 50 is further configured to trigger the segmentation unit 10 to re-start when the length of the PSDU aggregated by the aggregation unit 30 is determined to be greater than the difference between the maximum data length and the physical layer overhead length. Segmenting the MSDU into a plurality of sub-MSDUs of equal length until the aggregated unit 30 obtains the sub-MSDUs obtained by segmenting the segmented unit 10 and the CF generated corresponding to the MSDUs, and the aggregated PSDU is less than or equal to the The difference between the maximum data length and the physical layer overhead length.

In practical applications, the modules in the dimming device can be implemented by the CPU, microprocessor, or field programmable logic array (FPGA) in the dimming device.

The embodiment of the present invention also records a computer storage medium, wherein computer executable instructions are stored in the computer storage medium, and the computer executable instructions are used to execute the dimming method shown in FIG. 1 or FIG. 2 .

Those skilled in the art should understand that the embodiments of the present invention may be provided as methods, systems, or computer program products. Accordingly, the present invention can take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (14)

1. a kind of light-dimming method, which is characterized in that the described method includes:

Determine that the length of data service unit MSDU is greater than maximum data length and successively visits with physical layer overhead length and medium Ask the difference of control MAC layer overhead length；

In medium access control MAC layer, divide the sub- MSDU that MAC data service unit MSDU is multiple equal lengths；

Sub- MSDU after segmentation is encapsulated into respectively in Medium Access Control (MAC) Protocol Data Unit MPDU independent, and according to the mesh of light source Mark brightness value is respectively that each MPDU generates compensation frame CF；

It polymerize the MPDU and CF and is the physical layer service data PSDU of physical layer protocol data unit PPDU, and passes The defeated PPDU；

Wherein, the maximum data length is the product of the data rate of cycle T and link, and the cycle T is to flash critical melt The inverse of sum of fundamental frequencies rate CFF.

2. the method according to claim 1, wherein being multiple in the segmentation MAC data service unit MSDU After the sub- MSDU of equal length, the method also includes:

It is successively long with physical layer overhead length and MAC layer expense to determine that the length of the sub- MSDU is greater than maximum data length When the difference of degree, divide the sub- MSDU that the MSDU is multiple equal lengths again, until determining the length of obtained sub- MSDU Degree is less than or equal to the maximum data length successively difference with physical layer overhead length and MAC layer overhead length.

3. according to the method described in claim 2, it is characterized in that, the target brightness value according to light source is respectively each MPDU Generate compensation frame CF, comprising:

When determining light source intrinsic brilliance value and light source target brightness value difference, the target brightness value according to light source is respectively each MPDU Generate CF.

4. according to the method described in claim 3, it is characterized in that, the determining light source intrinsic brilliance value and light source target brightness When being worth different, the target brightness value according to light source is respectively that each MPDU generates CF, comprising:

The length n of the sequence of the data portion CFD of the CF is determined according to the following formula_CF:

Wherein, α indicates the target brightness value of light source, n_costIndicate the number of " 1 " in the part expense cost, n_MSDUIt indicates in MSDU The number of " 1 ", n_CFIndicate the number of " 1 " in CFD；size_costIndicate the length of the part cost, size_MSDUDescribed in expression The length of MSDU, size_CFIndicate the length of the CF；The cost includes the tail portion word of the stem MHR field of MAC layer, MAC layer Section, physical layer preamble code field, physical layer header field, the header field of CF and filling Pad field.

5. according to the method described in claim 3, it is characterized in that, the method also includes:

When determining that light source intrinsic brilliance value is identical as light source target brightness value, the sub- MSDU after the segmentation is encapsulated into respectively respectively From in independent Medium Access Control (MAC) Protocol Data Unit MPDU；

Using the MPDU as the part PSDU of PPDU, and transmit the PPDU.

6. according to the method described in claim 3, it is characterized in that, the polymerization MPDU and CF is physical layer protocol After the physical layer service data PSDU of data cell PPDU, the method also includes:

Determine that the length for the PSDU that polymerization obtains is less than or equal to the difference of the maximum data length and physical layer overhead length Value.

7. according to the method described in claim 6, it is characterized in that, determining the length for the PSDU that polymerization obtains greater than described When the difference of maximum data length and physical layer overhead length, the method also includes:

Again divide the sub- MSDU that the MSDU is multiple equal lengths, until according to obtained sub- MSDU and according to institute The corresponding CF generated of MSDU is stated, the PSDU polymerizeing is less than or equal to the difference of the maximum data length and physical layer overhead length Value.

8. a kind of dimming device, which is characterized in that the dimming device includes:

Determination unit, for the length for determining data service unit MSDU be greater than maximum data length successively with physical layer overhead When the difference of length and MAC layer overhead length, cutting unit is triggered；

Cutting unit, in medium access control MAC layer, dividing MAC data service unit MSDU to be multiple equal lengths Sub- MSDU；

Compensating unit, for the sub- MSDU after segmentation to be encapsulated into respectively in Medium Access Control (MAC) Protocol Data Unit MPDU independent, and Target brightness value according to light source is respectively that each MPDU generates compensation frame CF；

Polymerized unit, for polymerizeing the Physical Layer Service Data that the MPDU and CF is physical layer protocol data unit PPDU Unit PSDU；

Optical drive unit is used for transmission the PPDU；

Wherein, the maximum data length is the product of the data rate of cycle T and link, and the cycle T is to flash critical melt The inverse of sum of fundamental frequencies rate CFF.

9. dimming device according to claim 8, which is characterized in that

The determination unit, be also used to the length for determining the sub- MSDU be greater than maximum data length successively with physical layer overhead When the difference of length and MAC layer overhead length, triggers the cutting unit and divide the MSDU again for multiple equal lengths Sub- MSDU, until determine the length of obtained sub- MSDU be less than or equal to the maximum data length successively with physical layer overhead The difference of length and MAC layer overhead length；

The cutting unit is also used to divide again the sub- MSDU that the MSDU is multiple equal lengths.

10. dimming device according to claim 9, which is characterized in that

The compensating unit, when being also used to determine light source intrinsic brilliance value and light source target brightness value difference, according to the mesh of light source Mark brightness value is respectively that each MPDU generates CF.

11. dimming device according to claim 10, which is characterized in that

The compensating unit is also used to determine the length n of the sequence of the data portion CFD of the CF according to the following formula_CF:

Wherein, α indicates the target brightness value of light source, n_costIndicate the number of " 1 " in the part expense cost, n_MSDUIt indicates in MSDU The number of " 1 ", n_CFIndicate the number of " 1 " in CFD；size_costIndicate the length of the part cost, size_MSDUDescribed in expression The length of MSDU, size_CFIndicate the length of the CF；The cost includes the tail portion word of the stem MHR field of MAC layer, MAC layer Section, physical layer preamble code field, physical layer header field, the header field of CF and filling Pad field.

12. dimming device according to claim 10, which is characterized in that the dimming device further include:

Encapsulation unit, for when the compensating unit determines that light source intrinsic brilliance value is identical as light source target brightness value, by institute Sub- MSDU after stating segmentation is encapsulated into respectively in Medium Access Control (MAC) Protocol Data Unit MPDU independent；

The optical drive unit is also used to transmit the PPDU using the MPDU as the part PSDU of PPDU.

13. dimming device according to claim 12, which is characterized in that

The determination unit is also used to after the PSDU that the polymerized unit polymerize that the MPDU and CF is PPDU, really The length for polymerizeing the obtained PSDU calmly is less than or equal to the difference of the maximum data length and physical layer overhead length.

14. dimming device according to claim 13, which is characterized in that

The determination unit is also used to be greater than the maximum in the length for determining the PSDU that the polymerized unit polymerize When the difference of data length and physical layer overhead length, triggers the cutting unit and divide the MSDU again for multiple length phases Deng sub- MSDU, until sub- MSDU that the polymerized unit is divided according to the cutting unit and according to it is described The MSDU corresponding CF generated, the PSDU polymerizeing are less than or equal to the difference of the maximum data length and physical layer overhead length Value.