A visible light emission method, transmitting end, communication method and communication system based on light intensity plane matching and interleaving

Abstract

The present invention relates to a visible light emission method, a transmitting end, a communication method and a communication system based on light intensity plane matching interleaving. The visible light emission method of the present invention is based on CISK modulation mode, and an interleaving operation is added in the modulation process, and the interleaving operation includes the following steps: continuously and evenly dividing the coded data into P parts, each part is continuously divided into t groups, each group includes m coded bits; several coded bits in each group of coded data of the kth (k=1, 2, ..., P) part or several coded bits between different groups of coded data are swapped, so that the first p coded bits of each group of coded data are equal to the UPAM bits corresponding to the kth CSK intensity plane of the modulation. The present invention evenly maps the coded data on different CSK intensity planes through the interleaving operation, avoids the coded data from being concentrated on certain CSK intensity planes due to random mapping, and effectively improves the error performance of communication.

Description

Technical Field

[0001] The present invention relates to the field of visible light communication, and in particular to a visible light emission method, a transmitting end, a communication method and a communication system based on light intensity plane matching and interleaving. Background Art

[0002] With the continuous development of information technology, the future wireless communication network will be the Internet of Everything. In this wireless network, the exchange and transmission of information will grow exponentially, which will bring huge challenges to the limited radio spectrum resources. As an emerging communication technology, visible light communication has abundant visible light spectrum, which can greatly broaden the available bandwidth resources and break through the resource shortage problem faced by future wireless communication networks. In visible light communication networks, efficient and reliable data transmission is a key issue that needs to be solved. To address this problem, coding and modulation technology can provide a solution to a certain extent. Low-density parity check (LDPC) codes have attracted widespread attention due to their ability to approach the Shannon limit; however, LDPC codes themselves have some obvious defects, such as non-scalable code rate and high compilation complexity. To overcome this deficiency, the protograph low-density parity check (P-LDPC) code stands out. While inheriting the error correction performance advantages of LDPC codes, this code type also has the characteristics of simple code structure and low theoretical analysis complexity. In modulation technology, in order to meet the high-speed requirements of visible light communication, some high-spectral-efficiency modulation technologies, such as color shift key (CSK) spatial modulation and orthogonal frequency division multiplexing, have been proposed one after another.

[0003] In 2011, the IEEE 802.15.7 visible light communication standard gave the principle of CSK modulation, which can synthesize different colors of light by changing the instantaneous intensity of the red, green, and blue (RGB) LED lights while keeping the total light intensity unchanged. After a more in-depth study of the CSK modulation method, people proposed a joint modulation method based on color keying and pulse amplitude modulation (i.e., color intensity keying, Color-and-Intensity Shift Keying, CISK), which can greatly improve the data transmission efficiency in visible light communication systems. However, since the CISK modulation method introduces pulse amplitude modulation (PAM), the CISK constellation diagram is expanded from the two-dimensional CSK to the three-dimensional, and the minimum Euclidean distance of different constellations is different, so the error performance of the system is average. Summary of the invention

[0004] Based on this, the object of the present invention is to provide a visible light emission method, a transmitting end, a communication method and a communication system based on light intensity plane matching and interleaving.

[0005] A visible light emission method based on light intensity plane matching and interleaving, characterized in that it comprises the following steps:

[0006] S10, encoding the information to be sent into coded data in the original low-density parity-check code format;

[0007] S20, performing an interleaving operation on the coded data so that the coded data is evenly mapped on different CSK intensity planes to obtain interleaved data;

[0008] S30, performing color-and-intensity shift keying (CISK) modulation on the interleaved data to obtain CISK modulation symbols;

[0009] S40: Convert the CISK modulation symbols into optical signals and transmit them.

[0010] The visible light emission method described in the present invention is based on the CISK modulation method, and adds an interleaving operation in the modulation process to evenly map the encoded data on different CSK intensity planes, thereby avoiding the concentration of the encoded data on certain CSK intensity planes due to random mapping, and effectively improving the error performance of communication.

[0011] Furthermore, the step S20 includes the following sub-steps:

[0012] S21, continuously and evenly divide the coded data into P parts, each part is continuously divided into t groups, each group includes m coded bits;

[0013] S22. Swap the positions of several coded bits in each group of coded data in the kth (k=1, 2, ..., P) part or several coded bits between different groups of coded data so that the first p coded bits of each group of coded data are equal to the UPAM bits corresponding to the modulation of the kth CSK intensity plane.

[0014] Furthermore, the step S30 includes the following sub-steps:

[0015] S31, dividing the interleaved data into several groups of data to be modulated, each group of data to be modulated includes m coded bits, each group of data to be modulated is further divided into two parts, namely UPAM bits and CSK modulation bits, the UPAM bits include p coded bits, the CSK modulation bits include u (u=mp) coded bits;

[0016] S32A, modulate the UPAM bit into UPAM symbol Li (i=1,2,…,P=log2p);

[0017] S32B, modulate the CSK modulation bit into CSK symbol X j =[x r ,x g ,x b ] j (j=1,2,…,log2u);

[0018] S33, multiply the UPAM symbol and the CSK symbol to obtain the CISK modulation symbol S k =[L i x jr ,L i x jg ,L i x jb ] k (k=1,2,…,log2m).

[0019] Furthermore, the CISK modulation symbol is used to adjust the emitting light source, and the average light intensity of the emitting light source is

[0020] Furthermore, the present invention also provides a visible light communication method based on light intensity plane matching interleaving, comprising a transmitting method and a receiving method, wherein the transmitting method comprises any of the above-mentioned visible light transmitting methods, and the receiving method comprises the following steps:

[0021] S50, receiving the optical signal and converting it into an electrical signal;

[0022] S60, performing CISK demodulation on the electrical signal to obtain likelihood data;

[0023] S70, performing a deinterleaving operation on the likelihood data to obtain deinterleaved data;

[0024] S80, performing original image decoding on the deinterleaved data to obtain transmission information.

[0025] Furthermore, the present invention also provides a visible light transmitting end based on light intensity plane matching interleaving, the transmitting end comprising an original pattern encoder for encoding information to be transmitted into an original pattern low-density parity check code format to obtain encoded data;

[0026] An interleaver, used for performing an interleaving operation on the coded data to obtain interleaved data;

[0027] A CISK modulator, used for performing color-and-intensity shift keying (CISK) modulation on the interleaved data to obtain CISK modulation symbols;

[0028] The transmitter is used to convert CISK modulation symbols into optical signals and transmit the optical signals.

[0029] Furthermore, the interleaver comprises

[0030] A grouping module, used for continuously and evenly dividing the coded data into P parts, each part is continuously divided into t groups, each group includes m coded bits;

[0031] The replacement module is used to swap the positions of several coded bits in each group of coded data in the kth (k=1, 2, ..., P) part or several coded bits between different groups of coded data, so that the first p coded bits of each group of coded data are equal to the UPAM bits corresponding to the kth CSK intensity plane of modulation.

[0032] Furthermore, the CISK modulator comprises

[0033] A shunting module is used to divide the interleaved data into a plurality of groups of data to be modulated, each group of data to be modulated includes m coded bits, each group of data to be modulated is further divided into two parts, namely UPAM bits and CSK modulation bits, the UPAM bits include p coded bits, and the CSK modulation bits include u (u=mp) coded bits;

[0034] UPAM module, used to modulate UPAM bits into UPAM symbols L i (i=1,2,…,P=log2p);

[0035] CSK modulation module, used to modulate CSK modulation bits into CSK symbols X j =[x r ,x g ,x b ] j (j=1,2,…,log2u);

[0036] Fusion module, used to multiply UPAM symbol and CSK symbol to obtain CISK modulation symbol S k =[L i x jr ,L i x jg ,L i x jb ] k (k=1,2,…,log2m).

[0037] Furthermore, the emitter includes a red LED, a green LED and a blue LED, and the total average light intensity of the three LED light sources satisfies the relationship:

[0038] At the same time, the present invention also provides a visible light communication system based on light intensity plane matching interleaving, including a transmitting end and a receiving end, wherein the transmitting end is any of the transmitting ends described above; the receiving end includes

[0039] A receiver, used to receive the optical signal and convert it into an electrical signal;

[0040] A CISK demodulator, used for performing CISK demodulation on the electrical signal to obtain likelihood data;

[0041] A deinterleaver, used for performing a deinterleaving operation on the likelihood data to obtain deinterleaved data;

[0042] The original image decoder is used to perform original image decoding on the deinterleaved data to obtain the transmission information.

[0043] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Schematic diagram of a visible light communication system based on light intensity plane matching and interleaving;

[0045] Figure 2 The present invention is a flow chart of a visible light communication method based on light intensity plane matching and interleaving;

[0046] Figure 3 This is a comparison chart of the bit error performance simulation experiment results. DETAILED DESCRIPTION

[0047] Since the CISK modulation method introduces pulse amplitude modulation, the CISK constellation diagram is expanded from the two-dimensional CSK to the three-dimensional. There are several CSK intensity planes in the three-dimensional CISK constellation diagram, and several constellation points are distributed on each intensity plane. However, the minimum Euclidean distances of different CSK intensity planes are different, which means that the information bit error rate mapped on different CSK intensity planes is different. In the prior art, the specific CSK intensity plane to which the information is mapped depends on the information itself and the set mapping rules. Therefore, the information is easily mapped to the CSK intensity plane with a smaller minimum Euclidean distance. There may even be an extreme situation where all the information is mapped to the CSK intensity plane with a smaller minimum Euclidean distance, resulting in a higher bit error rate of the system.

[0048] Based on this, the present invention adds a specific interleaving operation in the CISK modulation process to evenly map the coded bits on different CSK intensity planes, effectively avoiding excessive concentration of information on a certain CSK intensity plane and improving the error performance of the system.

[0049] See also Figure 1The present invention provides a visible light communication system based on light intensity plane matching interleaving, including a transmitting end and a receiving end. By setting an interleaver with a specific interleaving rule at the transmitting end, the coded bits are mapped as evenly as possible to CSK intensity planes with different minimum Euclidean distances, thereby improving the error correction performance of the visible light communication system.

[0050] See also Figure 2 Based on the above system, the present invention also provides a CISK visible light communication method based on CSK intensity plane matching bit interleaving. By adding an interleaving operation in the CISK modulation process, the coded bits are mapped as evenly as possible to CSK intensity planes with different minimum Euclidean distances, thereby improving the error performance of the overall system.

[0051] In a specific implementation, the transmitting end includes a proto-image encoder, an interleaver, a CISK modulator and a transmitter.

[0052] The original image encoder is used to execute step S10: encoding the information to be sent into coded data in the original image low-density parity-check code format.

[0053] The interleaver is used to execute step S20: perform an interleaving operation on the coded data so that the coded data is evenly mapped on different CSK intensity planes to obtain interleaved data.

[0054] Specifically, the interleaver includes a grouping module and a permutation module.

[0055] The grouping module is used to execute step S21: continuously and evenly divide the coded data into P parts, and each part is continuously divided into t groups, each group includes m coded bits.

[0056] The replacement module is used to execute step S22: swap the positions of several coded bits in each group of coded data in the kth (k=1, 2, ..., P) part or several coded bits between different groups of coded data, so that the first p coded bits of each group of coded data are equal to the UPAM bits corresponding to the modulation of the kth CSK intensity plane.

[0057] The UPAM bits are modulated into corresponding UPAM symbols in a subsequent modulation process according to a preset modulation rule. Different UPAM symbols correspond to different CSK intensity planes, which means that the UPAM bits can determine which CSK intensity plane the group of coded data will be mapped to.

[0058] The CISK modulator is used to execute step S30: performing color keying and pulse amplitude (ie, color intensity keying, Color-and-Intensity Shift Keying, CISK) modulation on the interleaved data to obtain CISK modulation symbols.

[0059] Specifically, the CISK modulator includes a shunting module, a UPAM module, a CSK modulation module and a fusion module.

[0060] The diversion module is used to execute step S31: divide the interleaved data into several groups of data to be modulated, each group of data to be modulated includes m coding bits, and each group of data to be modulated is divided into two parts, namely UPAM bits and CSK modulation bits, the UPAM bits include p coding bits, and the CSK modulation bits include u (u=mp) coding bits.

[0061] The UPAM module is used to perform step S32A: modulate the UPAM bit into a UPAM symbol L i (i=1,2,…,P=log2p).

[0062] The CSK modulation module is used to perform step S32B: modulate the CSK modulation bit into a CSK symbol X j =[x r ,x g ,x b ] j (j=1,2,…,log2u).

[0063] Specifically, the UPAM symbol represents the CSK intensity plane, which is used to determine the instantaneous light intensity of the emitting light source; the CSK symbol represents the constellation point on the CSK intensity plane, which is used to determine the RGB three-color light intensity of the emitting light source, that is, x r Determines the intensity of red light, x g Determines the intensity of green light, x b Determines the intensity of blue light, and the sum of the intensities of the three colors of light is equal to the instantaneous intensity of the emitting light source.

[0064] The fusion module is used to execute step S33: multiply the UPAM symbol and the CSK symbol to obtain a CISK modulation symbol S k =[L i x jr ,L i x jg ,L i x jb ] k (k=1,2,…,log2m).

[0065] Furthermore, in order to avoid the problem of light flicker caused by excessive changes in light intensity, the average light intensity of the CISK modulation symbol is specified as

[0066] The transmitter is used to execute step S40: convert CISK modulation symbols into optical signals and transmit the optical signals.

[0067] Specifically, the transmitter includes a red LED, a green LED and a blue LED, and is modulated by the CISK symbol S k The red LED is controlled by L in the CISK modulation symbol. i x jr regulation, the green LED is subject to L i x jg regulation, the blue LED is subject to L i x jb Adjust so that the light emitted by the three LEDs is mixed to form mixed light and emitted to the outside.

[0068] The receiving end includes a receiver, a CISK demodulator, a deinterleaver and a proto-image decoder.

[0069] The receiver is used to perform step S50: receiving the optical signal and converting it into an electrical signal.

[0070] Specifically, the receiver includes three transmissive filters, red, green and blue, which respectively separate the mixed light emitted by the transmitter into red light, green light and blue light, and convert them into electrical signals via a photoelectric detector.

[0071] The CISK demodulator is used to execute step S60: perform CISK demodulation on the electrical signal to obtain likelihood data.

[0072] The deinterleaver is used to execute step S70: perform a deinterleaving operation on the likelihood data to obtain deinterleaved data.

[0073] The proto-image decoder is used to execute step S80: proto-image decoding is performed on the deinterleaved data to obtain transmission information.

[0074] In order to facilitate understanding of the above method, the (2,4)-CISK framework will be taken as an example for further explanation. It should be noted that this example is for the purpose of facilitating understanding, and is not intended to limit the method of the present invention. The method of the present invention is applicable to any (P,U)-CISK framework.

[0075] The (2,4)-CISK framework includes two CSK intensity planes, namely L1 and L2, and each CSK intensity plane has four constellation points. Correspondingly, in this example, step S21 is to divide the coded data into two parts in a continuous and even manner, and each part of the coded data is continuously divided into t groups (the value of t depends on the amount of actual coded data, and the more coded data, the larger t) and each group includes 3 coded bits. Among them, the first bit of each group of coded bits is used for subsequent modulation of UPAM symbols. If the bit is 1, it means that the modulation is CSK intensity plane L1, and if the bit is 0, it means that the modulation is CSK intensity plane L2; and the last two bits of each group of coded bits are used to modulate CSK symbols.

[0076] For the coded data of part 1, its main purpose is to map all the coded data to the CSK intensity plane L1. Correspondingly, step S22 in this example is to swap two coded bit positions in each group of coded data so that the first coded bit value is 1. Specifically, each coded bit is retrieved in turn. If the first coded bit is 1, no operation is performed on the group of coded data; if the first coded bit is not 1, the second coded bit is retrieved. If the second coded bit is 1, the first and second coded bits are swapped; if the second coded bit is not 1, the third coded bit is continued to be retrieved. If the third coded bit is 1, the first and third coded bits are swapped; if the third coded bit is not 1, the first bit of the next group of coded data is continued to be retrieved... and so on, until the first coded bit of the group of coded data is finally set to 1. The above swap operation is performed on each group of coded data in part 1, so that the first coded bit of each group of coded data is 1, that is, each group of coded data in part 1 is mapped to the CSK intensity plane L1.

[0077] Similarly, for the coded data of the second part, its main purpose is to map all the coded data to the CSK intensity plane L2. Correspondingly, the step S22 is to swap two coded bit positions in each group of coded data so that the first coded bit value is 0. Specifically, each coded bit is retrieved in turn. If the first coded bit is 0, no operation is performed on the group of coded data; if the first coded bit is not 0, the second coded bit is retrieved. If the second coded bit is 0, the first and second coded bits are swapped; if the second coded bit is not 0, the third coded bit is continued to be retrieved. If the third coded bit is 0, the first and third coded bits are swapped; if the third coded bit is not 0, the first bit of the next group of coded data is continued to be retrieved... and so on, until the first coded bit of the group of coded data is finally set to 0. The above swap operation is performed on each group of coded data in the second part, so that the first coded bit of each group of coded data is 0, that is, each group of coded data in the second part is mapped to the CSK intensity plane L2.

[0078] Through the above operation, the coded data is evenly mapped on different CSK intensity planes, which can avoid the coded data being concentrated on the CSK intensity plane with a smaller minimum Euclidean distance due to random mapping, and effectively improve the error performance of the system.

[0079] In order to more fully illustrate the beneficial effects of the present invention over the prior art, the following will be further elaborated in combination with simulation analysis and results. The systems used in the simulation are a non-interleaving system, a variable point matching interleaving system, and a CSK intensity plane matching interleaving system of the present invention, and the rule-(3, 6) original pattern code is selected as the error correction code. The basic matrix B of the rule-(3, 6) original pattern code (3,6) The code rate is 1 / 2 and satisfies the following relationship:

[0080] B (3,6) =[3,3]

[0081] For the (2, 4)-CISK framework, the PEXIT algorithm is used to evaluate the performance of the above systems. The decoding threshold values ​​obtained by the test are as follows:

[0082] Interleaving Scheme CSK intensity plane matching Variable point matching No interweaving Decoding threshold 2.724 3.145 2.952

[0083] The decoding threshold value of the regular-(3,6) original pattern code in the CSK intensity plane matching interleaving system is the smallest, indicating that the regular-(3,6) original pattern code has better waterfall performance in the CSK intensity plane matching interleaving system than in the variable degree matching interleaving system. At the same time, the CSK intensity plane matching interleaving system also has better waterfall performance than the case without interleaving.

[0084] Furthermore, a simulation experiment was conducted on the bit error performance of the above system to obtain Figure 3 The simulation results are shown in Figure 1. The vertical axis is the bit error rate, and the horizontal axis is the optical signal-to-noise ratio. The smaller the value, the better the bit error performance of the system. It can be found that the bit error performance of the CSK intensity plane matching interleaving system is better than that of the variable point matching interleaving system, and is also better than that of the non-interleaving system.

[0085] Compared with the prior art, the present invention considers the minimum Euclidean distance of constellation points on different CSK strength planes, and effectively improves the performance of the system by evenly mapping the encoded data to different CSK strength planes. In addition, the present invention does not need to consider the size of the variable point degree, nor does it need to calculate the mutual information of the variable points in advance, which effectively reduces the difficulty of design.

[0086] The above-mentioned embodiments only express the preferred implementation of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and the present invention is also intended to include these modifications and modifications.

Claims

1. A visible light emission method based on light intensity plane matching and interleaving, characterized in that: The following steps are involved: S10, encoding the information to be sent into coded data in the original low-density parity-check code format; S20, performing an interleaving operation on the coded data so that the coded data is evenly mapped on different CSK intensity planes to obtain interleaved data, comprising the following sub-steps: S21, continuously and evenly divide the coded data into P parts, each part is continuously divided into t groups, each group includes m coded bits; S22, swapping the positions of a number of coded bits in each group of coded data of the kth part or a number of coded bits between different groups of coded data, so that the first p coded bits of each group of coded data are equal to the UPAM bits corresponding to the kth CSK intensity plane of modulation, where k = 1, 2, ..., P; S30, performing color keying and pulse amplitude modulation on the interleaved data to obtain CISK modulation symbols, including the following sub-steps: S31, dividing the interleaved data into several groups of data to be modulated, each group of data to be modulated includes m coded bits, each group of data to be modulated is further divided into two parts, namely UPAM bits and CSK modulation bits, the UPAM bits include p coded bits, the CSK modulation bits include u coded bits, where u=mp; S32A, modulate the UPAM bit into UPAM symbol L i , where i = 1, 2, ..., P, and P = log2p; S32B, modulate the CSK modulation bit into CSK symbol X j =[x r ,x g ,x b ] j , where j = 1, 2, ..., U, and U = log2u; S33, multiply the UPAM symbol and the CSK symbol to obtain the CISK modulation symbol S k＝ [L i x jr ,L i x jg ,L i x jb ] k , where k = 1, 2, ..., M, and M = log2m; S40, converting the CISK modulation symbol into an optical signal and transmitting the optical signal; The CISK modulation symbol is used to adjust the emission light source, and the average light intensity of the emission light source 2. A visible light communication method based on light intensity plane matching interleaving, characterized in that: The invention comprises a transmitting method and a receiving method, wherein the transmitting method is the visible light transmitting method according to claim 1, and the receiving method comprises the following steps: S50, receiving the optical signal and converting it into an electrical signal; S60, performing CISK demodulation on the electrical signal to obtain likelihood data; S70, performing a deinterleaving operation on the likelihood data to obtain deinterleaved data; S80, performing original image decoding on the deinterleaved data to obtain transmission information.

3. A visible light transmitting end based on light intensity plane matching interleaving, characterized in that: The transmitting end includes The original image encoder is used to encode the information to be sent into coded data in the original image low-density parity check code format; An interleaver is used to perform an interleaving operation on the coded data so that the coded data is evenly mapped on different CSK intensity planes to obtain interleaved data; the interleaver includes A grouping module, used for continuously and evenly dividing the coded data into P parts, each part is continuously divided into t groups, each group includes m coded bits; A replacement module, used for replacing the positions of a number of coded bits in each group of coded data of the kth part or a number of coded bits between different groups of coded data, so that the first p coded bits of each group of coded data are equal to the UPAM bits corresponding to the kth CSK intensity plane of modulation, where k = 1, 2, ..., P; A CISK modulator is used to perform color keying and pulse amplitude modulation on the interleaved data to obtain CISK modulation symbols; the CISK modulator includes A shunting module is used to divide the interleaved data into a plurality of groups of data to be modulated, each group of data to be modulated includes m coded bits, each group of data to be modulated is further divided into two parts, namely UPAM bits and CSK modulation bits, the UPAM bits include p coded bits, the CSK modulation bits include u coded bits, where u=mp; UPAM module, used to modulate UPAM bits into UPAM symbols L i , where i = 1, 2, ..., P, and P = log2p; CSK modulation module, used to modulate CSK modulation bits into CSK symbols X j =[x r ,x g ,x b ] j , where j = 1, 2, ..., U, and U = log2u; Fusion module, used to multiply UPAM symbol and CSK symbol to obtain CISK modulation symbol S k＝ [L i x jr ,L i x jg ,L i x jb ] k , where k = 1, 2, ..., M, and M = log2m; A transmitter is used to convert CISK modulation symbols into optical signals and transmit the optical signals. The transmitter includes a red LED, a green LED and a blue LED. The total average light intensity of the three LED light sources satisfies the relationship:

4. A visible light communication system based on light intensity plane matching interleaving, characterized in that: It includes a transmitting end and a receiving end, wherein the transmitting end is the transmitting end as claimed in claim 3; the receiving end includes A receiver, used to receive the optical signal and convert it into an electrical signal; A CISK demodulator, used for performing CISK demodulation on the electrical signal to obtain likelihood data; A deinterleaver, used for performing a deinterleaving operation on the likelihood data to obtain deinterleaved data; The original image decoder is used to perform original image decoding on the deinterleaved data to obtain the transmission information.

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