Spherical decoding methods, apparatus and electronic equipment for visible light channels

Abstract

A spherical decoding method, apparatus, and electronic device for a visible light channel, the spherical decoding method comprising: obtaining a signal gain matrix H characterizing the relationship between a received optical signal vector y and a transmitted optical signal vector x; performing QR decomposition on the channel gain matrix H to obtain an orthogonal matrix Q and a first triangular matrix R; setting the off-diagonal elements of the first triangular matrix R to 0 to obtain a second triangular matrix R′; and decoding the received optical signal y of the i-th target photodiode. i The candidate emitted optical signals are searched sequentially, and the received optical signal y of the i-th target photodiode is analyzed. i Based on the analysis results, the candidate emitted optical signal is replaced according to the Euclidean distance from the candidate emitted optical signal until the Euclidean distance f is reached. i If the received optical signal y is less than the preset search radius r, then the received optical signal y is obtained. i The corresponding transmitted optical signal completes the reception of the optical signal y by the i-th target photodiode. i The decoding.

Description

Technical Field

[0001] This invention relates to the field of signal detection in wireless optical communication, and particularly to a spherical decoding method, apparatus, and electronic device for visible light channels. Background Technology

[0002] Multiple-in-Multiple-Out (MIMO) technology refers to a technique where information to be transmitted is preprocessed and synchronously transmitted through multiple antennas at the transmitting end, and received by multiple antennas at the receiving end, thereby improving the achievable data rate through spatial multiplexing. MIMO technology can effectively improve the achievable data rate, but the signals emitted by different antennas can interfere with each other, making signal detection difficult.

[0003] Signal detection is a crucial technology in communication systems; it involves the receiver processing the signal to recover the original signal. Maximum likelihood (ML) detection is one method that can achieve optimal bit error rate performance. However, in practical systems, ML methods are often difficult to implement in hardware. To approximate the low bit error rate characteristics of ML detection methods while maintaining relatively low computational complexity, spherical decoding has been proposed.

[0004] Spherical decoding reduces computational complexity through tree-based search, but it also presents some challenges. For example, the initial radius and the number of grid points affect the search speed. Even in the worst-case scenario, the computational complexity of spherical decoding remains nondeterministic polynomial (NP). Furthermore, under weak interference channel conditions, many redundant search steps in spherical decoding waste computational resources. Therefore, for weak interference channels, a signal detection method that strikes a good balance between complexity and decoding performance is needed. Summary of the Invention

[0005] In view of this, the main objective of the present invention is to provide a spherical decoding method, apparatus and electronic device for visible light channels, in order to partially solve at least one of the above-mentioned technical problems.

[0006] To achieve the above objectives, as one aspect of the present invention, a spherical decoding method for a visible light channel is provided, wherein the transmitting end of the visible light channel includes an array of m light-emitting diodes (LEDs), and the receiving end of the visible light channel includes an array of l photodiodes (p-LEDs), where l ≥ m. The LEDs are suitable for transmitting optical signals, and the photodiodes are suitable for receiving optical signals. Each LED corresponds to a target photodiode, and each target photodiode is suitable for receiving at least one candidate transmitted optical signal, including the corresponding transmitted optical signal emitted by the corresponding LED. The spherical decoding method includes:

[0007] Obtain a signal gain matrix H to characterize the relationship between the received optical signal vector y and the transmitted optical signal vector x, wherein the received optical signal vector y is obtained based on the received optical signal at the receiving end, and the transmitted optical signal vector x is obtained based on the transmitted optical signal at the transmitting end;

[0008] The channel gain matrix H is decomposed into an orthogonal matrix Q and a first triangular matrix R.

[0009] Set the off-diagonal elements of the first triangular matrix R to 0 to obtain the second triangular matrix R′;

[0010] The received optical signal y for the i-th target photodiode i The candidate emitted optical signals are searched sequentially, and the Euclidean distance between the received optical signal of the i-th target photodiode and the candidate emitted optical signal is analyzed. Based on the analysis results, the candidate emitted optical signal is replaced until the Euclidean distance f is reached. i The received optical signal y is obtained when the radius is less than the preset search radius r. i The corresponding transmitted optical signal is used to complete the reception of the received optical signal y of the i-th target photodiode. i The decoding; wherein, according to the conjugate transpose of the orthogonal matrix Q, the decoding is performed. * The received optical signal y is obtained by combining the second triangular matrix R′ with the second triangular matrix R′. i Distance increment e between the candidate emitted optical signal and the candidate emitted optical signal i Then the Euclidean distance f is obtained. i , where i is 1, 2, 3...m, and m is the number of emitted optical signals.

[0011] According to an embodiment of the present invention, after obtaining the received optical signal y i After receiving the corresponding transmitted optical signal, the spherical decoding method further includes:

[0012] Continue searching for the corresponding emitted light signal of the (i+1)th target photodiode until all emitted light signals are detected, thus completing the decoding.

[0013] According to an embodiment of the present invention, the candidate emitted light signal further includes the emitted light signal emitted by a light-emitting diode adjacent to the light-emitting diode corresponding to the target photodiode.

[0014] According to an embodiment of the present invention, the candidate transmitted optical signal and the received optical signal y i Euclidean distance f i Satisfies the following relationship:

[0015]

[0016] e i =z i -rii x i

[0017] Q * y = z

[0018] Among them, e i For the received optical signal y i The distance increment between the candidate emitted optical signal and the candidate emitted optical signal, z i Let r represent the i-th element of matrix z. ii Let Q represent the element in the i-th row and i-th column of matrix R. * Describe the conjugate transpose of the orthogonal matrix Q. * y represents the received optical signal vector.

[0019] According to an embodiment of the present invention, the gain matrix H is represented as follows:

[0020] y = Hx + n

[0021] Where y is the received optical signal vector, x is the received optical signal vector, and n is the noise signal vector.

[0022] According to an embodiment of the present invention, the diagonal elements of the first triangular matrix R are P times the maximum value of the off-diagonal elements in the same row, where the absolute value of P is greater than 1.

[0023] As a second aspect of the present invention, a spherical decoding device is also provided, comprising:

[0024] The transmitting end includes an array of m light-emitting diodes, which are suitable for emitting signals;

[0025] The receiving end includes an array of l photodiodes, wherein the photodiodes are adapted to receive optical signals, l ≥ m, each of the light-emitting diodes corresponds to a target photodiode, and each target photodiode is adapted to receive at least one candidate emitted optical signal including the corresponding emitted optical signal emitted by the corresponding light-emitting diode;

[0026] The gain matrix acquisition module is suitable for obtaining the signal gain matrix H, which characterizes the relationship between the received optical signal vector y and the transmitted optical signal vector x.

[0027] The decomposition module is used to perform QR decomposition on the channel gain matrix H to obtain an orthogonal matrix Q and a first triangular matrix R; and to set the off-diagonal elements of the triangular matrix R to 0 to obtain a second triangular matrix R′.

[0028] The search and analysis module is suitable for analyzing the received optical signal y of the i-th target photodiode. iThe candidate emitted optical signals are searched sequentially, and the Euclidean distance between the received optical signal of the i-th target photodiode and the candidate emitted optical signal is analyzed. Based on the analysis results, the candidate emitted optical signal is replaced until the Euclidean distance f is reached. i The received optical signal y is obtained when the radius is less than the preset search radius r. i The corresponding transmitted optical signal completes the reception of the optical signal y by the i-th target photodiode. i The decoding; wherein, according to the conjugate transpose of the orthogonal matrix Q, the decoding is performed. * The received optical signal y is obtained by combining the second triangular matrix R′ with the second triangular matrix R′. i Distance increment e between the candidate emitted optical signal and the candidate emitted optical signal i Then the Euclidean distance f is obtained. i , where i is 1, 2, 3...m, and m is the number of emitted optical signals.

[0029] As a third aspect of the invention, an electronic device is also provided, comprising:

[0030] one or more processors;

[0031] Storage device for storing one or more programs.

[0032] When the one or more programs are executed by the one or more processors, the one or more processors perform the method described above.

[0033] As a fourth aspect of the invention, a computer-readable storage medium is also provided, having stored executable instructions thereon that, when executed by a processor, cause the processor to perform the method described above. Attached Figure Description

[0034] Figure 1 The schematic diagram illustrates the principle of a receiver for a visible light channel provided according to an embodiment of the present invention;

[0035] Figure 2 A flowchart illustrating a spherical decoding method provided according to an embodiment of the present invention is shown schematically.

[0036] Figure 3 A flowchart illustrating a spherical decoding method according to another embodiment of the present invention is shown.

[0037] Figure 4 The diagram illustrates a projection of light from a light-emitting diode onto the surface of a photodiode array according to another embodiment of the present invention. Detailed Implementation

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0039] The transmitting end of the visible light channel includes an array of m light-emitting diodes (LEDs), and the receiving end of the visible light channel includes an array of l photodiodes (PDs), where l ≥ m and l and m are both positive integers. The LEDs are used to transmit optical signals, and the photodiodes are used to receive optical signals. Each LED corresponds to a target photodiode, and each target photodiode is used to receive at least one candidate transmitted optical signal, including the corresponding transmitted optical signal emitted by the corresponding LED.

[0040] Figure 1 The schematic diagram illustrates the principle of a receiver for a visible light channel provided according to an embodiment of the present invention.

[0041] like Figure 1 As shown, the visible light channel in this embodiment of the invention is a weak interference visible light channel. Most of the light signal emitted by each LED will fall within the receiving range of the corresponding PD. Due to the light divergence characteristics of LEDs, a small portion of the light signal will fall into the receiving range of adjacent PDs that have already received signals from other LEDs, causing interference. Each LED will only interfere with a few PDs that are adjacent to its corresponding PD, and will not interfere with other PDs that are not adjacent to its corresponding PD.

[0042] Figure 2 A flowchart illustrating a spherical decoding method provided according to an embodiment of the present invention is shown.

[0043] like Figure 2 As shown, the spherical decoding method for visible light channels includes the following steps:

[0044] Step S1: Obtain the signal gain matrix H to characterize the relationship between the received optical signal vector y and the transmitted optical signal vector x, wherein the received optical signal vector y is obtained from the received optical signal at the receiving end, and the transmitted optical signal vector x is obtained from the transmitted optical signal at the transmitting end.

[0045] Step S2: Perform QR decomposition on the channel gain matrix H to obtain the orthogonal matrix Q and the first triangular matrix R.

[0046] Step S3: Set the off-diagonal elements of the first triangular matrix R to 0 to obtain the second triangular matrix R′.

[0047] Step S4: Receive the optical signal y from the i-th target photodiode. iThe candidate emitted optical signals are searched sequentially. The Euclidean distance between the received optical signal of the i-th target photodiode and the candidate emitted optical signal is analyzed. Based on the analysis results, the candidate emitted optical signal is replaced until the Euclidean distance f is reached. i If the received optical signal y is less than the preset search radius r, then the received optical signal y is obtained. i The corresponding transmitted optical signal completes the reception of the optical signal y by the i-th target photodiode. i The decoding.

[0048] Wherein, according to the conjugate transpose of the orthogonal matrix Q * The received optical signal y is obtained from the second triangular matrix R′. i Distance increment e between the candidate emitted optical signal and the candidate emitted optical signal i Then the Euclidean distance f is obtained. i , where i is 1, 2, 3...m, and m is the number of emitted optical signals.

[0049] refer to Figure 3 According to an embodiment of the present invention, when the received optical signal y is obtained... i After receiving the corresponding transmitted optical signal, the spherical decoding method also includes:

[0050] Continue searching for the corresponding emitted light signal of the (i+1)th target photodiode until all emitted light signals are detected, thus completing the decoding.

[0051] According to an embodiment of the present invention, in step S1, the gain matrix H is expressed as: y = Hx + n, where y is the received optical signal vector, x is the transmitted optical signal vector, n is the noise signal vector, and h is the received optical signal vector. uv This represents the element in the u-th row and v-th column of the matrix.

[0052] According to an embodiment of the present invention, in step S2, the diagonal elements of the first triangular matrix R are P times the maximum value of the off-diagonal elements in the same row, and the absolute value of P is greater than 1.

[0053] According to an embodiment of the present invention, in step S4:

[0054] Analyze the received optical signal y of the i-th target photodiode. i Euclidean distance f from the candidate emitted optical signal i In the Euclidean distance f i If the distance is greater than or equal to the preset search radius r, then pruning is performed in advance, and the candidate transmission signal is changed until the Euclidean distance f is reached. i Less than the preset search radius r.

[0055] Candidate transmitted optical signal and received optical signal y i Euclidean distance f i The following relationship must be satisfied:

[0056]

[0057] e i =z i -r ii x i (2)

[0058] Q * y=z (3)

[0059] Among them, e i To receive optical signal y i The distance increment between the candidate emitted optical signal and the candidate emitted optical signal, z i T represents the i-th element of matrix z. ii Let Q represent the element in the i-th row and i-th column of matrix R. * Describe the conjugate transpose of the orthogonal matrix Q. * y represents the received optical signal vector.

[0060] According to an embodiment of the present invention, the derivation process of equations (1)-(3) is as follows:

[0061]

[0062] Where ||·|| represents the second norm of the vector, Q * Let Q denote the conjugate transpose of matrix Q. * Given y = z and the off-diagonal elements of matrix R′ are 0, we can obtain:

[0063]

[0064] Where x j and x i Let z represent the j-th and i-th transmitted signals, respectively. i Let r represent the i-th element of vector z. ij Let r represent the element in the i-th row and j-th column of matrix R. ii Let e ​​represent the element in the i-th row and i-th column of matrix R, and m represent the number of transmitted signals. i =z i -r ii x i Then we can obtain equation (1).

[0065] According to an embodiment of the present invention, a spherical decoding device is also provided, comprising: a transmitter, a receiver, a gain matrix acquisition module, a decomposition module, and a search and analysis module.

[0066] The transmitting end includes an array of m light-emitting diodes (LEDs) for emitting signals. The receiving end includes an array of l photodiodes for receiving optical signals, where l ≥ m. Each LED corresponds to a target photodiode, and each target photodiode is suitable for receiving at least one candidate transmitted optical signal, including the corresponding transmitted optical signal emitted by its corresponding LED. A gain matrix acquisition module is used to obtain a signal gain matrix H characterizing the relationship between the received optical signal vector y and the transmitted optical signal vector x. A decomposition module is used to perform QR decomposition on the channel gain matrix H to obtain an orthogonal matrix Q and a first triangular matrix R; and to set the off-diagonal elements of the triangular matrix R to 0 to obtain a second triangular matrix R′. A search and analysis module is used to analyze the received optical signal y of the i-th target photodiode. i The candidate emitted optical signals are searched sequentially, and the Euclidean distance between the received optical signal of the i-th target photodiode and the candidate emitted optical signal is analyzed. Based on the analysis results, the candidate emitted optical signal is replaced until the Euclidean distance f is reached. i The received optical signal y is obtained when the radius is less than the preset search radius r. i The corresponding transmitted optical signal completes the reception of the optical signal y by the i-th target photodiode. i The decoding; wherein, according to the conjugate transpose of the orthogonal matrix Q, the decoding is performed. * The received optical signal y is obtained by combining the second triangular matrix R′ with the second triangular matrix R′. i Distance increment e between the candidate emitted optical signal and the candidate emitted optical signal i Then the Euclidean distance f is obtained. i Where i is 1, 2, 3...m, and m is the number of emitted optical signals.

[0067] According to an embodiment of the present invention, an electronic device is also provided, comprising: one or more processors; and a storage device for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors perform the method as described above.

[0068] According to an embodiment of the present invention, a computer-readable storage medium is also provided, on which executable instructions are stored, which, when executed by a processor, cause the processor to perform the method described above.

[0069] According to a specific embodiment of the present invention, such as Figure 4 As shown, the transmitter uses 16 LEDs, and the receiver uses 16 PDs. The LED light spots are projected onto the surface of the PD array as follows. Figure 3 As shown, most of the LED light spot's projection falls within the corresponding PD's receiving range, while a small portion falls into the receiving range of adjacent PDs, causing interference.

[0070] We investigated the performance of the low-complexity spherical decoding method (i.e., setting R as a diagonal matrix) for weakly interfered channels under two interference intensities. For comparison, the traditional spherical decoding method (i.e., R′ remains a triangular matrix) was used with the same processing steps. Under the first interference intensity, |P| > 6 was calculated for R′. Then, the LED spot was moved to the right, increasing the interference intensity, resulting in |P| > 5 under the second interference intensity. In the experiment, the data transmitted by each LED was set to 1e7 bits, so the total data transmitted by the system was 16 * 1e7 bits. To investigate the performance of the spherical decoding method provided in this embodiment, we statistically analyzed the running time and decoding error rate, and the results are shown in Table 1.

[0071] As can be seen from Table 1, compared with the common spherical decoding method, the spherical decoding method for weak interference channels provided in this embodiment of the invention has lower complexity and significantly shorter running time; at the same time, the decoding performance of the two is basically the same, which illustrates the reliability and efficiency of the method.

[0072] Table 1

[0073]

[0074] The spherical decoding method proposed in this embodiment of the invention reduces the number of searches in the spherical decoding process and lowers the complexity.

[0075] The spherical decoding method proposed in this invention, compared with the traditional spherical decoding method, can shorten the computation time while maintaining essentially the same decoding accuracy.

[0076] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A spherical decoding method for visible light channels, wherein, The visible light channel is a weak interference channel, and the transmitter of the visible light channel includes... An array of light-emitting diodes, wherein the receiver of the visible light channel includes... An array of photodiodes The light-emitting diode (LED) is suitable for emitting optical signals, and the photodiode is suitable for receiving optical signals. Each LED corresponds to a target photodiode, and each target photodiode is suitable for receiving at least one candidate emitted optical signal, including the corresponding emitted optical signal emitted by the corresponding LED. The spherical decoding method includes: Obtain the vector used to characterize the received optical signal and the emitted light signal vector Channel gain matrix relating the two The received optical signal vector The transmitted optical signal vector is obtained based on the received optical signal at the receiving end. It is obtained based on the emitted optical signal from the transmitting end; The channel gain matrix Perform QR decomposition to obtain an orthogonal matrix. With the first triangular matrix ; The first triangular matrix Set the off-diagonal elements to 0 to obtain the second triangular matrix. ; Received optical signal for the i-th target photodiode The candidate emitted optical signals are searched sequentially, and the received optical signal of the i-th target photodiode is analyzed. Based on the analysis results, the candidate emitted optical signal is replaced according to the Euclidean distance f until the Euclidean distance is reached. i The received optical signal is obtained when the radius is less than the preset search radius r. The corresponding transmitted optical signal completes the reception of the optical signal by the i-th target photodiode. The decoding; wherein, based on the orthogonal matrix The conjugate transpose matrix and the second triangular matrix The received optical signal is obtained Distance increment between candidate emitted optical signals Then the Euclidean distance f is obtained. i , where i is 1, 2, 3...m, and m is the number of emitted optical signals.

2. The spherical decoding method according to claim 1, after obtaining the received optical signal... After receiving the corresponding transmitted optical signal, the spherical decoding method further includes: Continue searching for the corresponding emitted light signal of the (i+1)th target photodiode until all emitted light signals are detected, thus completing the decoding.

3. The spherical decoding method according to claim 1, wherein, The candidate emitted light signal also includes the emitted light signal emitted by the light-emitting diode adjacent to the light-emitting diode corresponding to the target photodiode.

4. The spherical decoding method according to claim 1, wherein, The candidate transmitted optical signal and the received optical signal Euclidean distance f i Satisfies the following relationship: in, For the received optical signal The distance increment between the candidate emitted optical signal and the candidate emitted optical signal. Representation matrix The i-th element, Representation matrix The element in the i-th row and i-th column, Represents an orthogonal matrix The conjugate transpose matrix y represents the received optical signal vector.

5. The spherical decoding method according to claim 1, wherein, The channel gain matrix It is expressed as follows: in, It is the received optical signal vector. It is the emitted light signal vector. It is a noise signal vector.

6. The spherical decoding method according to claim 1, wherein, The diagonal elements of the first triangular matrix R are P times the maximum value of the off-diagonal elements in the same row, where the absolute value of P is greater than 1.

7. A spherical decoding device for implementing a spherical decoding method for a visible light channel, wherein the visible light channel is a weak interference channel, the spherical decoding device comprising: The transmitter, including An array of light-emitting diodes, wherein the light-emitting diodes are suitable for emitting signals; The receiving end, including An array of photodiodes, wherein the photodiodes are adapted to receive optical signals. Each of the light-emitting diodes corresponds to a target photodiode, and each target photodiode is adapted to receive at least one candidate emitted light signal, including the corresponding emitted light signal emitted by the corresponding light-emitting diode; The gain matrix acquisition module is suitable for obtaining a vector characterizing the received optical signal. and the emitted light signal vector Channel gain matrix relating the two ; The decomposition module is used to decompose the channel gain matrix. Perform QR decomposition to obtain an orthogonal matrix. With the first triangular matrix ; and the triangular matrix Set the off-diagonal elements to 0 to obtain the second triangular matrix. ; The search and analysis module is suitable for analyzing the received optical signal of the i-th target photodiode. The candidate emitted optical signals are searched sequentially, and the Euclidean distance between the received optical signal of the i-th target photodiode and the candidate emitted optical signal is analyzed. Based on the analysis results, the candidate emitted optical signal is replaced until the Euclidean distance f is reached. i The received optical signal is obtained when the radius is less than the preset search radius r. The corresponding transmitted optical signal completes the reception of the optical signal by the i-th target photodiode. The decoding; wherein, based on the orthogonal matrix The conjugate transpose matrix and the second triangular matrix The received optical signal is obtained Distance increment between candidate emitted optical signals Then the Euclidean distance f is obtained. i , where i is 1, 2, 3...m, m is the number of emitted light signals, and the i-th emitted light signal is generated by the i-th target photodiode.

8. An electronic device, comprising: One or more processors; Storage device for storing one or more programs. Wherein, when the one or more programs are executed by the one or more processors, the one or more processors perform the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having stored thereon executable instructions that, when executed by a processor, cause the processor to perform the method according to any one of claims 1 to 6.

Images