A visible light communication method and system based on CDMA

Abstract

The present invention discloses a visible light communication method and system based on CDMA, and relates to the technical field of visible light communication. The method is applied to a visible light communication system based on CDMA, and the visible light communication system includes a transmitting end and a user end, and the transmitting end includes a plurality of LEDs. The transmitting end generates a position sensing spread spectrum code of each LED and a dedicated spread spectrum code of the user end, and generates an optical signal of the LED according to original user information. The transmitting end sends the optical signal to the user end through the LED, and the user end receives the optical signal to obtain a received signal, and separates the DC component of the received signal through an AC / DC separation circuit, collects energy from the DC component, despreads the received signal according to the dedicated spread spectrum code, obtains the original user information, despreads the received signal according to the position sensing spread spectrum code of the LED, and determines the position information of the user end, thereby performing energy collection and position sensing during visible light communication.

Description

Technical Field

[0001] The present invention relates to the technical field of visible light communication, and in particular to a visible light communication method and system based on CDMA. Background Art

[0002] With the rapid development of mobile Internet and Internet of Things technology, traditional radio frequency communication can no longer meet the growing demand for communication capacity. The next generation of mobile communication faces huge challenges such as shortage of spectrum resources, high energy consumption and severe interference. As a new type of wireless communication technology, visible light communication technology relies on the existing indoor lighting equipment light emitting diodes (LEDs) to replace radio frequency base stations to send signals, and uses photodetectors to collect optical signals, thereby realizing wireless information transmission. Since LED light sources can simultaneously load user communication data and light intensity information for location perception, an integrated system of visible light communication and location perception has emerged. It has many advantages such as no need for spectrum authorization, high location perception accuracy, low carbon and environmental protection. In particular, due to its unique advantage of strong electromagnetic compatibility, it can be used in electromagnetically sensitive and highly confidential fields such as nuclear power plants, hospitals, and military manufacturing industries, thereby avoiding electromagnetic interference and electromagnetic leakage problems that may be caused by traditional wireless radio frequency signals.

[0003] At present, some studies have applied orthogonal frequency division multiple access (OFDMA) technology, code division multiple access (CDMA) technology, and time division multiple access (TDMA) access technology to the integrated system of visible light communication and position perception, but have not considered energy collection while performing communication and position perception. Summary of the invention

[0004] In order to solve the technical problem that the prior art fails to realize position perception and energy collection during visible light communication, an embodiment of the present invention provides a CDMA-based visible light communication method and system. The technical solution is as follows:

[0005] On the one hand, a CDMA-based visible light communication method is provided, the method is applied to a CDMA-based visible light communication system, the visible light communication system includes a transmitting end and a user end, the transmitting end includes a plurality of LEDs, and the method includes:

[0006] The transmitting end generates a position sensing spreading code for each LED and a unique spreading code for the user end according to a preset spreading code set, and sends the position sensing spreading code for each LED and the unique spreading code for the user end to the user end;

[0007] The transmitter generates optical signals of multiple LEDs according to the original user information. For each LED, the optical signal S of the LED is generated by the following formula: n (t):

[0008]

[0009] Among them, u m (i) is the i-th original user information in a set of original user information to be sent to the m-th user terminal, m and i are positive integers, M is the number of user terminals, u m (i)∈{0,1},1≤i≤N bit , N bit is the number of bits of a set of original user information to be sent, P t is the transmit power of the LED, 0<ρ<1 is the power allocation factor for location sensing, 1-ρ is the power allocation factor for communication, T=LT c is the symbol period, T c is the clock time interval, L is the code length of the location-aware spreading code and the exclusive spreading code;

[0010] C p (t) is the waveform corresponding to the position-aware spread spectrum code of the LED. The corresponding waveform is determined by the following formula based on the position-aware spread spectrum code:

[0011]

[0012] Among them, c p (l) = c p (l+L), and is a duration T c The unit rectangular pulse, c p (l) is the location-aware spreading code, and L is the code length of the location-aware spreading code;

[0013] C m (t) is the waveform corresponding to the exclusive spread spectrum code of the mth user terminal. The corresponding waveform is determined by the following formula according to the exclusive spread spectrum code:

[0014]

[0015] Among them, c m (l) = c m (l+L), and is a duration T c The unit rectangular pulse, c p (l) is a dedicated spreading code, and L is the code length of the dedicated spreading code;

[0016] The transmitting end sends the optical signals of the multiple LEDs to the user end through the multiple LEDs;

[0017] The user end receives the optical signals sent by the multiple LEDs through the photoelectric detector to obtain the received signals;

[0018] The user end separates the DC component and the AC component in the received signal through an AC / DC separation circuit; the user end collects energy from the separated DC component and determines the collected energy value;

[0019] The user end despreads the received signal using a dedicated spreading code to obtain a first despread signal, and determines original user information corresponding to the user end based on the first despread signal;

[0020] The user end uses the position-aware spread spectrum codes of the multiple LEDs to despread the received signal, generates the light intensity information of the multiple LEDs, and determines the position information of the user end according to the light intensity information of the multiple LEDs.

[0021] Optionally, the determining of the collected energy value is achieved by:

[0022] Determine the collected energy value as EH = fI DC V oc , where I DC is the separated DC component, f is the filling factor, V oc is the open-loop circuit voltage, Among them, V t is the thermal voltage and I0 is the dark saturation current.

[0023] Optionally, the preset spread spectrum code set is a unipolar code set The number of codes in the unipolar code set is K, the length of the code is L, the weight of the code is w, and the length of the zero correlation zone is Z cz .

[0024] Optionally, generating the position-aware spread spectrum code of each LED and the exclusive spread spectrum code of the user terminal according to a preset spread spectrum code set includes:

[0025] Group multiple LEDs into groups of at least three LEDs, and assign a position-aware spread spectrum code set to each group of LEDs Among them C po ∈C,P≥3, P is the number of LEDs in each LED group, the position-aware spread spectrum code set of each LED group is the same, the number of LEDs in each group is the same, the position-aware spread spectrum code of each LED in each LED group is different, and the position-aware spread spectrum code of each LED belongs to the position-aware spread spectrum code set;

[0026] The spreading codes in the unipolar code set C that are not in the position-aware spreading code set are allocated to each user terminal as exclusive spreading codes of each user terminal.

[0027] Optionally, the user terminal uses a dedicated spreading code to despread the received signal to obtain a first despread signal, which is performed by the following formula:

[0028] (i-1)T≤t≤iT, where c d (t) is the waveform corresponding to the user-side dedicated spreading code, r d (t) is the received signal, and L is the code length of the dedicated spreading code.

[0029] Optionally, the determining the original user information corresponding to the user terminal based on the first despread signal is performed by using the following formula:

[0030] Among them, D d (i) is the first despread signal, N bit is the number of bits of the original user information, T = LT c is the symbol period, T c is the clock time interval, and L is the code length of the exclusive spreading code.

[0031] Optionally, the user end uses the position-aware spread spectrum codes of the multiple LEDs to despread the received signal and generate the light intensity information of the multiple LEDs, which is performed by the following formula:

[0032] Among them, r d (t) is the received signal, c p (t) is the waveform corresponding to the position sensing spread spectrum code of the pth LED, p is a positive integer, N bit is the number of bits of the original user information.

[0033] On the other hand, a CDMA-based visible light communication system is provided, the visible light communication system is used to implement the CDMA-based visible light communication method provided in an embodiment of the present invention, the system includes a transmitting end and a user end, the transmitting end includes a plurality of LEDs;

[0034] The transmitting end is configured to generate a position sensing spreading code for each LED and a unique spreading code for the user end according to a preset spreading code set, and send the position sensing spreading code for each LED and the unique spreading code for the user end to the user end;

[0035] The optical signals of multiple LEDs are generated according to the original user information. For each LED, the optical signal S of the LED is generated by the following formula: n (t):

[0036]

[0037] Among them, u m (i) is the i-th original user information in a set of original user information to be sent to the m-th user terminal, m and i are positive integers, M is the number of user terminals, u m (i)∈{0,1},1≤i≤N bit , Nbit is the number of bits of a set of original user information to be sent, P t is the transmit power of the LED, 0<ρ<1 is the power allocation factor for location sensing, 1-ρ is the power allocation factor for communication, T=LT c is the symbol period, T c is the clock time interval, L is the code length of the location-aware spreading code and the exclusive spreading code;

[0038] C p (t) is the waveform corresponding to the position-aware spread spectrum code of the LED. The corresponding waveform is determined by the following formula based on the position-aware spread spectrum code:

[0039]

[0040] Among them, c p (l) = c p (l+L), and is a duration T c The unit rectangular pulse, c p (l) is the location-aware spreading code, and L is the code length of the location-aware spreading code;

[0041] C m (t) is the waveform corresponding to the exclusive spread spectrum code of the mth user terminal. The corresponding waveform is determined by the following formula according to the exclusive spread spectrum code:

[0042]

[0043] Among them, c m (l) = c m (l+L), and is a duration T c The unit rectangular pulse, c p (l) is a dedicated spreading code, and L is the code length of the dedicated spreading code;

[0044] Sending optical signals of the plurality of LEDs to a user end through the plurality of LEDs;

[0045] The user end is configured to receive the optical signals sent by the plurality of LEDs through a photodetector to obtain a received signal;

[0046] Separating the DC component and AC component in the received signal by an AC / DC separation circuit;

[0047] The user end collects energy from the separated DC component and determines the collected energy value;

[0048] Despreading the received signal using a dedicated spreading code to obtain a first despread signal, and determining original user information corresponding to the user terminal based on the first despread signal;

[0049] The received signal is despread using the position-aware spread spectrum codes of the multiple LEDs to generate light intensity information of the multiple LEDs, and the position information of the user end is determined based on the light intensity information of the multiple LEDs.

[0050] On the other hand, a CDMA-based visible light communication device is provided, the visible light communication device comprising:

[0051] processor;

[0052] The memory stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the method provided by the embodiment of the present invention is implemented.

[0053] On the other hand, a computer-readable storage medium is provided, in which a program code is stored. The program code can be called by a processor to execute the method provided by an embodiment of the present invention.

[0054] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0055] The embodiment of the present invention provides a visible light communication method based on CDMA, in which a transmitting end generates a position sensing spread spectrum code for each LED and an exclusive spread spectrum code for a user end, and generates an optical signal of the LED according to original user information. The transmitting end sends the optical signal to the user end through the LED, the user end receives the optical signal, obtains a received signal, separates the DC component of the received signal through an AC / DC separation circuit, collects energy from the DC component, despreads the received signal according to the exclusive spread spectrum code, obtains the original user information, despreads the received signal according to the position sensing spread spectrum code of the LED, and determines the position information of the user end, thereby performing energy collection and position sensing during visible light communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0057] Figure 1 It is a schematic diagram of the structure of a CDMA-based visible light communication system provided by an embodiment of the present invention;

[0058] Figure 2 is a communication bit error rate distribution diagram provided by an embodiment of the present invention;

[0059] Figure 3 is a position perception error distribution diagram provided by an embodiment of the present invention;

[0060] Figure 4 is an energy collection capability distribution diagram provided by an embodiment of the present invention;

[0061] Figure 5 It is a structural schematic diagram of a CDMA-based visible light communication device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0062] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0063] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0064] In the embodiments of the present invention, "image" and "picture" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they intend to express are the same. "of", "corresponding, relevant" and "corresponding" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they intend to express are the same.

[0065] In the embodiments of the present invention, sometimes a subscript such as W1 may be mistakenly written as a non-subscript such as W1. When the difference is not emphasized, the meanings to be expressed are consistent.

[0066] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0067] The present invention provides a visible light communication method based on CDMA, which is applied to Figure 1 The CDMA-based visible light communication system shown includes a transmitter and a user end, the transmitter includes a plurality of LEDs, and the method includes:

[0068] The transmitting end generates the position-aware spread spectrum code of each LED and the exclusive spread spectrum code of the user end according to the preset spread spectrum code set, and sends the position-aware spread spectrum code of each LED and the exclusive spread spectrum code of the user end to the user end. In some embodiments, the transmitting end can send the position-aware spread spectrum code of each LED and the exclusive spread spectrum code of the user end to the user end through a cloud server.

[0069] Optionally, the preset spread spectrum code set is a unipolar code set The number of codes in the unipolar code set is K, the length of the code is L, the weight of the code is w, and the length of the zero correlation zone is Z cz .

[0070] Optionally, generating a position-aware spread spectrum code for each LED and a dedicated spread spectrum code for the user terminal according to a preset spread spectrum code set includes:

[0071] Group multiple LEDs into groups of at least three LEDs, and assign a position-aware spread spectrum code set to each group of LEDs Among them C po ∈C,P≥3, P is the number of LEDs in each LED group, the position-aware spread spectrum code sets of the LED groups are the same, the number of LEDs in each group is the same, the position-aware spread spectrum codes of the LEDs in each LED group are different, and the position-aware spread spectrum codes of the LEDs belong to the position-aware spread spectrum code set.

[0072] The spreading codes in the unipolar code set C that are not in the position-aware spreading code set are allocated to each user terminal as exclusive spreading codes of each user terminal.

[0073] In some embodiments, the present invention evenly distributes N LEDs on the roof to support M users to communicate, sense location and collect energy simultaneously (N≥M-3), and uses a multi-light source visible light position sensing algorithm based on received signal strength to obtain the location information of any user. N and M are positive integers.

[0074] Uses unipolar code sets that require no additional bias As a spread spectrum code set, the number of codes in the code set is K, the code length is L, the code weight is w, and the zero correlation zone length is Zcz. The code set construction and code set parameters can be flexibly selected according to the actual needs of the system. The above code set is used to spread and despread the signal to ensure that the signals between user terminals do not interfere with each other, and at the same time realize the multiplexing and separation of communication, location perception information and energy signals.

[0075] Since the multi-light source visible light position sensing algorithm based on the received signal strength needs to obtain the intensity information of at least 3 LEDs, at least 3 LEDs are divided into a group and the same position sensing spread spectrum code set is assigned to each group of LEDs. Among them C po ∈C,P≥3, at this time, different LEDs in each group are loaded with different ID information. The remaining codes in the spread spectrum code set C except the location-aware spread spectrum code set will be allocated to different user terminals as exclusive spread spectrum codes of the user terminals to support M=KP user terminals to communicate.

[0076] For example, four LEDs are evenly distributed on the roof to support one user terminal to simultaneously communicate, sense location, and collect energy. The visible light three-sided position sensing algorithm is used to obtain the location information of the user terminal. The system uses a unipolar OZCZ code set that does not require additional bias. As a spreading code set, the number of codes in the code set is 5, the code length is 5, the code weight is 1, and the zero correlation zone length is 0. The above code set is used to spread and despread the signal to ensure that the signals between users do not interfere with each other, and at the same time realize the multiplexing and separation of communication, location perception information and energy signals.

[0077] The four LEDs are divided into a group and the same position-aware spread spectrum code set is assigned to each group of LEDs. in At this time, different LEDs in each group are loaded with different ID information. c5 in the spread spectrum code set C is allocated to the first user end as the exclusive spread spectrum code of the first user end to support the user end to communicate.

[0078] The transmitter generates optical signals of multiple LEDs according to the original user information. For each LED, the optical signal S of the LED is generated by the following formula: n (t):

[0079]

[0080] Among them, u m (i) is the i-th original user information in a set of original user information to be sent to the m-th user terminal, m and i are positive integers, M is the number of user terminals, u m (i)∈{0,1},1≤i≤N bit , N bit is the number of bits of a set of original user information to be sent, P t is the transmit power of the LED, 0<ρ<1 is the power allocation factor for location sensing, 1-ρ is the power allocation factor for communication, T=LT c is the symbol period, T c is the clock time interval, and L is the code length of the location-aware spreading code and the exclusive spreading code.

[0081] C p (t) is the waveform corresponding to the position-aware spread spectrum code of the LED. The corresponding waveform is determined by the following formula based on the position-aware spread spectrum code:

[0082]

[0083] Among them, c p (l) = c p (l+L), and is a duration T cThe unit rectangular pulse, c p (l) is the location-aware spreading code, and L is the code length of the location-aware spreading code.

[0084] C m (t) is the waveform corresponding to the exclusive spread spectrum code of the mth user terminal. The corresponding waveform is determined by the following formula according to the exclusive spread spectrum code:

[0085]

[0086] Among them, c m (l) = c m (l+L), and is a duration T c The unit rectangular pulse, c p (l) is the exclusive spreading code, and L is the code length of the exclusive spreading code.

[0087] For example, assuming that the i-th original user information of the user is u m (i)∈{0,1},1≤i≤10000. After spread spectrum and OOK modulation, the signal sent by the nth LED can be expressed as

[0088] s n (t) = P t [ρc p (t)+(1-ρ)u1(i)c1(t)], (i-1)T≤t≤iT,

[0089] Among them, P t =5W is the LED transmission power, C p (t) is the waveform corresponding to the position sensing spread spectrum code of the LED. ρ = 0.5 is the power allocation factor for position sensing, and the power allocation factor for communication is 0.5. T = LT c is the symbol period, T c is the clock time interval, and L is the code length of the location-aware spreading code and the exclusive spreading code.

[0090] The transmitting end sends the optical signals of the multiple LEDs to the user end through the multiple LEDs.

[0091] The user end receives the light signals sent by multiple LEDs through a photodetector to obtain a received signal. In some embodiments, the user uses a silicon photocell as a photodetector to ensure a better energy collection capability of the system. The received signal is an AC / DC mixed signal, which contains information required for communication and location sensing as well as an energy signal.

[0092] The user end separates the DC component and the AC component in the received signal through an AC / DC separation circuit, collects energy from the separated DC component, and determines the collected energy value.

[0093] The user end despreads the received signal using a dedicated spreading code to obtain a first despread signal, and determines original user information corresponding to the user end based on the first despread signal.

[0094] The user end uses the position-aware spread spectrum codes of the multiple LEDs to despread the received signal, generates the light intensity information of the multiple LEDs, and determines the position information of the user end according to the light intensity information of the multiple LEDs.

[0095] Optionally, determining the collected energy value is achieved by:

[0096] Determine the collected energy value as EH = fI DC V oc , where I DC is the separated DC component, f is the filling factor, V oc is the open-loop circuit voltage, Among them, V t is the thermal voltage, I o is the dark saturation current.

[0097] Optionally, the user end uses a dedicated spreading code to despread the received signal to obtain a first despread signal, which is performed by the following formula:

[0098] Among them, c d (t) is the waveform corresponding to the user-side dedicated spreading code, r d (t) is the received signal, and L is the code length of the dedicated spreading code.

[0099] Optionally, original user information corresponding to the user terminal is determined based on the first despread signal, and the original user information is determined by the following formula:

[0100] Among them, D d (i) is the first despread signal, N bit is the number of bits of the original user information, T = LT c is the symbol period, T c is the clock time interval, and L is the code length of the exclusive spreading code.

[0101] Optionally, the user end uses the position-aware spread spectrum codes of multiple LEDs to despread the received signal and generate the light intensity information of multiple LEDs, which is performed by the following formula:

[0102] Among them, r d (t) is the received signal, c p (t) is the position-aware spread spectrum code of the pth LED, p is a positive integer, N bit is the number of bits of the original user information.

[0103] On the other hand, a CDMA-based visible light communication system is provided. The visible light communication system is used to implement the CDMA-based visible light communication method provided in an embodiment of the present invention. The system includes a transmitting end and a user end. The transmitting end includes multiple LEDs.

[0104] The transmitting end is configured to generate a position-aware spreading code for each LED and a user-specific spreading code according to a preset spreading code set, and send the position-aware spreading code for each LED and the user-specific spreading code to the user end.

[0105] The optical signals of multiple LEDs are generated according to the original user information. For each LED, the optical signal S of the LED is generated by the following formula: n (t):

[0106]

[0107] Among them, u m (i) is the i-th original user information in a set of original user information to be sent to the m-th user terminal, m and i are positive integers, M is the number of user terminals, u m (i)∈{0,1},1≤i≤N bit , N bit is the number of bits of a set of original user information to be sent, P t is the transmit power of the LED, 0<ρ<1 is the power allocation factor for location sensing, 1-ρ is the power allocation factor for communication, T=LT c is the symbol period, T c is the clock time interval, and L is the code length of the location-aware spreading code and the exclusive spreading code.

[0108] C p (t) is the waveform corresponding to the position-aware spread spectrum code of the LED. The corresponding waveform is determined by the following formula based on the position-aware spread spectrum code:

[0109] Among them, c p (l) = c p (l+L), and is a duration T c The unit rectangular pulse, c p (l) is the location-aware spreading code, and L is the code length of the location-aware spreading code.

[0110] C m (t) is the waveform corresponding to the exclusive spread spectrum code of the mth user terminal. The corresponding waveform is determined by the following formula according to the exclusive spread spectrum code:

[0111] Among them, cm (l) = c m (l+L), and is a duration T c The unit rectangular pulse, c p (l) is the exclusive spreading code, and L is the code length of the exclusive spreading code.

[0112] The optical signals of the multiple LEDs are sent to the user end through the multiple LEDs.

[0113] The user end is configured to receive optical signals sent by multiple LEDs through a photodetector to obtain a received signal.

[0114] The DC component and AC component in the received signal are separated by an AC / DC separation circuit.

[0115] The user end collects energy from the separated DC component and determines the collected energy value.

[0116] The received signal is despread using a dedicated spreading code to obtain a first despread signal, and original user information corresponding to the user terminal is determined based on the first despread signal.

[0117] The received signal is despread using the position-aware spread spectrum codes of the multiple LEDs to generate light intensity information of the multiple LEDs, and the position information of the user end is determined based on the light intensity information of the multiple LEDs.

[0118] In some embodiments, a multi-light source visible light position sensing algorithm based on received signal strength can be combined to determine the position information of the user terminal based on the light intensity information of multiple LEDs. For example, a multi-light source visible light position sensing algorithm based on received signal strength can be used to determine the distance between the LED and the user terminal based on the light intensity information of the LED, and the position of the user terminal can be determined by combining the distances between the three LEDs and the user terminal.

[0119] The CDMA-based visible light communication method and system provided by the embodiment of the present invention has a communication bit error rate of mostly 3.8×10 -3 Below the bit error rate threshold, the distribution results are as follows Figure 2 As shown, except for the four corners, the bit error rate is 3.8×10 -3 The error rate is below the bit error rate threshold. The position perception error is below 0.08m. The position perception error distribution results are as follows: Figure 3 As shown. The energy harvesting capability is 2.7×10 -7 J above, such as Figure 4 As shown, 2.7×10 -7 In summary, the CDMA-based visible light communication method and system provided by the present invention exhibit good communication, location perception and energy collection performance.

[0120] On the other hand, a computer-readable storage medium is provided, in which a program code is stored. The program code can be called by a processor to execute the method provided by an embodiment of the present invention.

[0121] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0122] The embodiment of the present invention provides a visible light communication method based on CDMA, in which a transmitting end generates a position sensing spread spectrum code for each LED and an exclusive spread spectrum code for a user end, and generates an optical signal of the LED according to original user information. The transmitting end sends the optical signal to the user end through the LED, the user end receives the optical signal, obtains a received signal, separates the DC component of the received signal through an AC / DC separation circuit, collects energy from the DC component, despreads the received signal according to the exclusive spread spectrum code, obtains the original user information, despreads the received signal according to the position sensing spread spectrum code of the LED, and determines the position information of the user end, thereby performing energy collection and position sensing during visible light communication.

[0123] Figure 5 is a schematic diagram of a structure of a CDMA-based visible light communication device provided by an embodiment of the present invention, such as Figure 5 As shown, optionally, the CDMA-based visible light communication device 410 may include a first processor 2001 .

[0124] Optionally, the CDMA-based visible light communication device 410 may further include a memory 2002 and a transceiver 2003 .

[0125] The first processor 2001, the memory 2002 and the transceiver 2003 may be connected via a communication bus.

[0126] Combine the following Figure 4 The components of the CDMA-based visible light communication device 410 are specifically introduced as follows:

[0127] The first processor 2001 is the control center of the CDMA-based visible light communication device 410, which can be a processor or a general term for multiple processing elements. For example, the first processor 2001 is one or more central processing units (CPUs), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present invention, such as one or more microprocessors (digital signal processors, DSPs), or one or more field programmable gate arrays (FPGAs).

[0128] Optionally, the first processor 2001 may perform various functions of the SSS device 410 by running or executing a software program stored in the memory 2002 , and calling data stored in the memory 2002 .

[0129] In a specific implementation, as an embodiment, the first processor 2001 may include one or more CPUs, such as Figure 5 CPU0 and CPU1 are shown in FIG.

[0130] In a specific implementation, as an embodiment, the CDMA-based visible light communication device 410 may also include multiple processors, such as Figure 5 The first processor 2001 and the second processor 2004 are shown in FIG. Each of these processors can be a single-core processor (single-CPU) or a multi-core processor (multi-CPU). The processor here can refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0131] The memory 2002 is used to store the software program for executing the solution of the present invention, and is controlled to be executed by the first processor 2001. The specific implementation method can refer to the above method embodiment, which will not be repeated here.

[0132] Optionally, the memory 2002 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 2002 may be integrated with the first processor 2001, or may exist independently, and may be connected to the first processor 2001 through the interface circuit ( Figure 5 (not shown) is coupled to the first processor 2001, which is not specifically limited in this embodiment of the present invention.

[0133] The transceiver 2003 is used to communicate with a network device or a terminal device.

[0134] Optionally, the transceiver 2003 may include a receiver and a transmitter ( Figure 5 The receiver is used to implement a receiving function, and the transmitter is used to implement a sending function.

[0135] Optionally, the transceiver 2003 may be integrated with the first processor 2001, or may exist independently, and communicate with the first processor 2001 through the interface circuit ( Figure 5 (not shown) is coupled to the first processor 2001, which is not specifically limited in this embodiment of the present invention.

[0136] It should be noted that Figure 5 The structure of the CDMA-based visible light communication device 410 shown in the figure does not constitute a limitation on the router, and the actual knowledge structure recognition device may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0137] In addition, the technical effects of the CDMA-based visible light communication device 410 can refer to the technical effects of the CDMA-based visible light communication device method described in the above method embodiment, which will not be repeated here.

[0138] It should be understood that the first processor 2001 in the embodiment of the present invention may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0139] It should also be understood that the memory in the embodiments of the present invention may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0140] The above embodiments can be implemented in whole or in part by software, hardware (such as circuits), firmware or any other combination. When implemented by software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that contains one or more available media sets. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a tape), an optical medium (for example, a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state hard disk.

[0141] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship, but it may also indicate an "and / or" relationship. Please refer to the context for specific understanding.

[0142] In the present invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can be represented by: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0143] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0144] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0145] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described equipment, devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0146] In the several embodiments provided by the present invention, it should be understood that the disclosed devices, apparatuses and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0147] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0148] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0149] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0150] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A visible light communication method based on CDMA, characterized in that: The method is applied to a CDMA-based visible light communication system, the visible light communication system includes a transmitting end and a user end, the transmitting end includes a plurality of LEDs, and the method includes: The transmitting end generates a position sensing spread spectrum code for each LED and a dedicated spread spectrum code for the user end according to a preset spread spectrum code set, and sends the position sensing spread spectrum code for each LED and the dedicated spread spectrum code for the user end to the user end; The transmitting end generates the optical signals of the plurality of LEDs respectively according to the original user information, and generates the optical signal S of the LED by the following formula for each LED: n (t): Among them, u m (i) is the i-th original user information in a set of original user information to be sent to the m-th user terminal, m and i are positive integers, M is the number of user terminals, u m (i)∈{0,1},1≤i≤N bit , N bit is the number of bits of a set of original user information to be sent, P t is the transmit power of the LED, 0<ρ<1 is the power allocation factor for location sensing, 1-ρ is the power allocation factor for communication, T=LT c is the symbol period, T c is a clock time interval, and L is the code length of the location-aware spreading code and the dedicated spreading code; c p (t) is the waveform corresponding to the position-aware spread spectrum code of the p-th LED. The corresponding waveform is determined by the following formula based on the position-aware spread spectrum code: Among them, c p (l) = c p (l+L), and is a duration T c The unit rectangular pulse, c p (l) is the location awareness spread spectrum code, and L is the code length of the location awareness spread spectrum code; c m (t) is the waveform corresponding to the exclusive spread spectrum code of the mth user terminal, and the corresponding waveform is determined by the following formula according to the exclusive spread spectrum code: Among them, c m (l) = c m (l+L), and is a duration T c The unit rectangular pulse, c m (l) is the dedicated spreading code, and L is the code length of the dedicated spreading code; The transmitting end transmits the optical signals of the plurality of LEDs to the user end through the plurality of LEDs; The user end receives the optical signals sent by the plurality of LEDs through a photoelectric detector to obtain a received signal; The user end separates the DC component and the AC component in the received signal through an AC / DC separation circuit; the user end collects energy from the separated DC component and determines the collected energy value; The user end despreads the received signal using the dedicated spreading code to obtain a first despread signal, and determines original user information corresponding to the user end based on the first despread signal; The user end uses the position-aware spread spectrum codes of the multiple LEDs to despread the received signal, generates light intensity information of the multiple LEDs, and determines the position information of the user end according to the light intensity information of the multiple LEDs.

2. The CDMA-based visible light communication method according to claim 1, characterized in that: The determination of the collected energy value is achieved by: Determine the collected energy value as EH = fI DC V oc , where I DC is the separated DC component, f is the filling factor, V oc is the open-loop circuit voltage, Among them, V t is the thermal voltage, I o is the dark saturation current.

3. The CDMA-based visible light communication method according to claim 1, characterized in that: The preset spread spectrum code set is a unipolar code set The number of codes in the unipolar code set is K, the length of the code is L, the weight of the code is w, and the length of the zero correlation zone is Z. cz .

4. The CDMA-based visible light communication method according to claim 3, characterized in that: The generating of the position sensing spread spectrum code of each LED and the exclusive spread spectrum code of the user terminal according to the preset spread spectrum code set includes: The plurality of LEDs are grouped into groups, wherein at least three LEDs are grouped into a group, and a position-aware spread spectrum code set is assigned to each group of LEDs. Among them C po ∈C,P≥3, P is the number of LEDs in each LED group, the position-aware spread spectrum code set of each LED group is the same, the number of LEDs in each group is the same, the position-aware spread spectrum code of each LED in each LED group is different, and the position-aware spread spectrum code of each LED belongs to the position-aware spread spectrum code set; The spreading codes in the unipolar code set C that are not in the position-aware spreading code set are allocated to each user terminal as exclusive spreading codes of each user terminal.

5. The CDMA-based visible light communication method according to claim 1, characterized in that: The user end uses the dedicated spreading code to despread the received signal to obtain a first despread signal, which is performed by the following formula: Among them, c d (t) is the waveform corresponding to the user-side dedicated spreading code, r d (t) is the received signal, and L is the code length of the dedicated spread spectrum code.

6. The CDMA-based visible light communication method according to claim 1, characterized in that: The original user information corresponding to the user terminal is determined based on the first despread signal, and the original user information is determined by the following formula: Among them, D d (i) is the first despread signal, N bit is the number of bits of the original user information, T = LT c is the symbol period, T c is the clock time interval, and L is the code length of the exclusive spreading code.

7. The CDMA-based visible light communication method according to claim 1, characterized in that: The user end uses the position-aware spread spectrum codes of the multiple LEDs to despread the received signal and generate the light intensity information of the multiple LEDs, which is performed by the following formula: Among them, r d (t) is the received signal, c p (t) is the waveform corresponding to the position sensing spread spectrum code of the pth LED, p is a positive integer, N bit is the number of bits of the original user information.

8. A visible light communication system based on CDMA, characterized in that: The visible light communication system is used to implement the CDMA-based visible light communication method as claimed in any one of claims 1 to 7, wherein the system comprises a transmitting end and a user end, and the transmitting end comprises a plurality of LEDs; The transmitting end is configured to generate a position-aware spreading code for each LED and a dedicated spreading code for the user end according to a preset spreading code set, and send the position-aware spreading code for each LED and the dedicated spreading code for the user end to the user end; The optical signals of the plurality of LEDs are respectively generated according to the original user information. For each LED, the optical signal S of the LED is generated by the following formula: n (t): Among them, u m (i) is the i-th original user information in a set of original user information to be sent to the m-th user terminal, m and i are positive integers, M is the number of user terminals, u m (i)∈{0,1},1≤i≤N bit , N bit is the number of bits of a set of original user information to be sent, P t is the transmit power of the LED, 0<ρ<1 is the power allocation factor for location sensing, 1-ρ is the power allocation factor for communication, T=LT c is the symbol period, T c is a clock time interval, and L is the code length of the location-aware spreading code and the dedicated spreading code; c p (t) is the waveform corresponding to the position-aware spread spectrum code of the p-th LED. The corresponding waveform is determined by the following formula based on the position-aware spread spectrum code: Among them, c p (l) = c p (l+L), and is a duration T c The unit rectangular pulse, c p (l) is the location awareness spread spectrum code, and L is the code length of the location awareness spread spectrum code; c m (t) is the waveform corresponding to the exclusive spread spectrum code of the mth user terminal, and the corresponding waveform is determined by the following formula according to the exclusive spread spectrum code: Among them, c m (l) = c m (l+L), and is a duration T c The unit rectangular pulse, c m (l) is the dedicated spreading code, and L is the code length of the dedicated spreading code; Sending the optical signals of the plurality of LEDs to a user end through the plurality of LEDs; The user end is configured to receive the optical signals sent by the plurality of LEDs through a photoelectric detector to obtain a received signal; Separating the DC component and the AC component in the received signal by an AC / DC separation circuit; The user end collects energy from the separated DC component and determines the collected energy value; Despreading the received signal using the dedicated spreading code to obtain a first despread signal, and determining original user information corresponding to the user terminal based on the first despread signal; The received signal is despread using the location-aware spread spectrum codes of the multiple LEDs to generate light intensity information of the multiple LEDs, and the location information of the user terminal is determined based on the light intensity information of the multiple LEDs.

9. A CDMA-based visible light communication device, characterized in that: The visible light communication device comprises: processor; A memory having computer-readable instructions stored thereon, wherein when the computer-readable instructions are executed by the processor, the method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores program code, and the program code can be called by a processor to execute the method as claimed in any one of claims 1 to 7.

Images