阅读说明：本技术 一种基于光码分多址的多用户共振光通信系统及方法 (Multi-user resonance optical communication system and method based on optical code division multiple access ) 是由 黄川� 崔曙光 田源明 李东旭 于 2021-10-22 设计创作，主要内容包括：本发明公开了一种基于光码分多址的多用户共振光通信系统及方法,包括基站和移动端,所述移动端包括位于不同用户处的收发信机；所述基站与每一个收发信机之间形成共振腔；所述基站包括第一回复反射器、第一增益介质、第一电光调制器、第一分束器、第一光电探测器、第一信号处理板、第二光电探测器、第一同步装置和第二信号处理板；所述收发信机包括第二回复反射器、第二增益介质、第二分束器、第三光电探测器、耦合器、第三信号处理板、第二同步装置和第二电光调制器。本发明通过编码解码结构设计,实现了多个用户在同一时间与发射机无干扰地进行通信,为共振光通信在多用户场景中的应用提供了便利。(The invention discloses a multi-user resonance optical communication system and a method based on optical code division multiple access, comprising a base station and a mobile terminal, wherein the mobile terminal comprises transceivers positioned at different users; a resonant cavity is formed between the base station and each transceiver; the base station comprises a first return reflector, a first gain medium, a first electro-optic modulator, a first beam splitter, a first photoelectric detector, a first signal processing board, a second photoelectric detector, a first synchronization device and a second signal processing board; the transceiver comprises a second retro-reflector, a second gain medium, a second beam splitter, a third photodetector, a coupler, a third signal processing board, a second synchronization device and a second electro-optical modulator. The invention realizes that a plurality of users can communicate with the transmitter at the same time without interference through the design of the coding and decoding structure, and provides convenience for the application of the resonant optical communication in a multi-user scene.)

1. A multi-user resonance optical communication system based on optical code division multiple access is characterized in that: the system comprises a base station (1) and a mobile terminal (2), wherein the mobile terminal comprises transceivers positioned at different users; a resonant cavity is formed between the base station and each transceiver;

the base station (1) comprises a first recovery reflector (11), a first gain medium (12), a first electro-optic modulator (13), a first beam splitter (14), a first photoelectric detector (15), a first signal processing board (16), a second photoelectric detector (17), a first synchronization device (18) and a second signal processing board (19);

resonant light from any transceiver is transmitted to a first return reflector (11) after passing through a first electro-optic modulator (13) and a first gain medium (12), is reflected by the first return reflector (11) according to an original path, and is transmitted to the transceiver after passing through the first gain medium (12) and the first electro-optic modulator (13);

the resonance light transmitted by the first recovery reflector (11) is transmitted to a first beam splitter (14) and is divided into a beam of transmission light and a beam of reflection light, the transmission light is sent into a first photoelectric detector (15), and the reflection light is sent into a second photoelectric detector (17); the first photoelectric detector (15) performs photoelectric conversion on input light and inputs an electric signal into the first signal processing board (16), the first signal processing board (16) determines code words of all users according to a code table recorded in a register of the first signal processing board in advance, and decodes received signals by using the code words to restore information of all users; the second photoelectric detector (17) carries out photoelectric conversion on input light and inputs an electric signal into the first synchronization device (18), the first synchronization device (18) carries out real-time detection on a synchronization head in the electric signal, when the fact that the synchronization head is just finished is detected, a notice is sent to the second signal processing board (19), the second signal processing board (19) generates sending information for each user after receiving the notice, code words of each user are determined according to a code table recorded in a register of the second signal processing board, the code results of each user are summed after the sending information is coded by the code words of each user, then the coding results are input into the first electro-optical modulator (13), and the first electro-optical modulator (13) loads the input information on resonance light and then sends the input information to a transceiver of each user.

2. The optical communication system according to claim 1, wherein the optical communication system comprises: the transceiver comprises a second retro-reflector (21), a second gain medium (22), a second beam splitter (23), a third photodetector (24), a coupler (25), a third signal processing board (26), a second synchronization device (27) and a second electro-optical modulator (28);

the resonance light from the base station (1) is transmitted to a second beam splitter (23) through a second electro-optical modulator (28), a beam of transmission light and a beam of reflection light are obtained through beam splitting of the second beam splitter (23), the transmission light obtained through beam splitting is transmitted to a second retro-reflector (21) through a second gain medium (22) and then transmitted to the base station through the second gain medium (22), the second beam splitter (23) and the second electro-optical modulator (28) after being reflected;

after the third photoelectric detector (24) performs photoelectric conversion on the signal, the output electric signal is input into a coupler (25), and the coupler divides the input electric signal into two paths of signals with equal or unequal power: one signal is input into a third signal processing board (26) for demodulation, and the other signal is input into a second synchronization device (27); the third signal processing board (26) demodulates the received information according to the pre-recorded code words to recover the information; the second synchronizer (27) detects the input signal in real time, when the synchronization head of the electric signal is detected to be just finished, the information to be sent is generated and encoded by using a pre-recorded code word, and then the encoded information is input into the second electro-optical modulator (28), and the second electro-optical modulator (28) loads the received electric signal on resonance light and sends the electric signal to the base station (1).

3. The optical communication system according to claim 2, wherein the optical communication system comprises: the first retro-reflector (11) adopts a retro-reflector with the reflectivity of 90% and the transmissivity of 10%; the second retro-reflector (21) adopts a retro-reflector with the reflectivity of 100% and the transmissivity of 0%; registers are integrated in the first signal processing board (16), the second signal processing board (19), the third signal processing board (26) and the second synchronization device (27).

4. A multi-user resonant optical communication method based on optical code division multiple access, which adopts the system of any one of claims 1 to 3, characterized in that: the method comprises the following steps:

s1, a base station (1) generates different and mutually orthogonal code words for each user, and stores the code words of each user to form a code table; the code word is an optical orthogonal code; saving code tables in registers of a first signal processing board (16) and a second signal processing board (19); for each subscriber, storing the codeword corresponding to the subscriber in a register of a third signal processing board (26) in the subscriber's transceiver;

s2, the base station (1) encodes the information sent to each user, sums the encoded data, inputs the summed data into a first electro-optical modulator (13) for modulation and sending, and receives and decodes the signals from the transceiver;

and S3, after the transceiver of each user uses a second electro-optical modulator (28) to complete photoelectric conversion, decoding the received signals by using the pre-recorded code words to recover own signals, and coding and transmitting the signals to be transmitted.

5. The optical communication method of claim 4, wherein the method comprises: each frame data between the base station (1) and the mobile terminal is composed of a synchronous head and information data.

6. The optical communication method of claim 5, wherein the method comprises: the step S2 includes:

s201, transmitting resonance light transmitted by the first recovery reflector (11) to the first beam splitter (14) to be split into a beam of transmission light and a beam of reflection light, transmitting the transmission light to the first photoelectric detector (15), and transmitting the reflection light to the second photoelectric detector (17);

s202, a first photoelectric detector (15) performs photoelectric conversion on input light and inputs an electric signal into a first signal processing board (16), the first signal processing board (16) determines code words of all users according to a code table recorded in a register in advance, and decodes received signals by using the code words to restore information of all users;

s203, the second photoelectric detector (17) performs photoelectric conversion on input light and inputs an electric signal into the first synchronization device (18), the first synchronization device (18) detects a synchronization head in the electric signal in real time, and when the synchronization head is detected to be just finished, a notice is sent to the second signal processing board (19);

and S204, after receiving the notification, the second signal processing board (19) generates sending information for each user, determines code words of each user according to a code table recorded in a register in advance, codes the sending information by using the code words of each user, sums the coding results of each user, inputs the sum into the first electro-optical modulator (13), and after loading the input information on resonant light, the first electro-optical modulator (13) sends the input information to the transceiver of each user.

7. The optical communication method of claim 5, wherein the method comprises: the step S3 includes:

s301, after photoelectric conversion is carried out on the signal by the third photoelectric detector (24), the output electric signal is input into a coupler (25), and the coupler divides the input electric signal into two paths of signals with equal or unequal power: one signal is input into a third signal processing board (26) for demodulation, and the other signal is input into a second synchronization device (27);

s302, demodulating the received information by a third signal processing board (26) according to the pre-recorded code word to restore the information;

s303, the second synchronization device (27) detects the input signal in real time, when the synchronization head of the electric signal is detected to be just finished, information to be sent is generated and is coded by using a pre-recorded code word, then the coded information is input into the second electro-optical modulator (28), and the second electro-optical modulator (28) loads the received electric signal onto resonance light and sends the resonance light to the base station (1).

Technical Field

The present invention relates to resonant optical communication, and more particularly, to a multi-user resonant optical communication system and method based on optical code division multiple access.

Background

In order to meet the demand of future communication development and realize high-speed broadband wireless communication, new spectrum resources must be developed to a high frequency band. Since the wavelength of light is short and has a frequency of several hundred THz, using light as a carrier of wireless communication will certainly become an important technical means for future wireless communication. The technology is an emerging wireless optical communication technology, wherein the technology forms stable light beams by using resonant cavities and uses the stable light beams as carriers to realize wireless communication, has high transmission rate and good mobility, and can break through the bottleneck of development of the wireless optical communication technology.

However, when a plurality of users are involved in simultaneous communication with the base station, how each user receives/transmits information required by itself becomes a difficulty in the resonant optical communication.

The multiple access technique is a key technique for realizing multi-user communication, which can expand the capacity of a communication system and enable signals of different users to be received and demodulated respectively without interference. In the current multi-user resonant optical communication system, research on multiple access technology is lacked, which restricts the development of resonant optical communication. Therefore, it is a problem to be solved by the development of the multi-user resonant optical communication technology to provide an appropriate multiple access technology to allow each user to receive/transmit information without interference.

The optical code division multiple access is a common multiple access mode in optical communication, and has the advantages of large system capacity, high frequency band utilization rate, strong anti-interference performance, good confidentiality and the like. How to combine the optical code division multiple access technology with the characteristics of resonant light to apply the technology to multi-user resonant optical communication is a feasible direction for developing the multi-user resonant optical communication technology.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a multi-user resonance optical communication system and a method based on optical code division multiple access. The method provides convenience for application of resonant optical communication in a multi-user scene.

The purpose of the invention is realized by the following technical scheme: a multi-user resonance optical communication system based on optical code division multiple access comprises a base station and a mobile terminal, wherein the mobile terminal comprises transceivers positioned at different users; a resonant cavity is formed between the base station and each transceiver;

the base station comprises a first return reflector, a first gain medium, a first electro-optic modulator, a first beam splitter, a first photoelectric detector, a first signal processing board, a second photoelectric detector, a first synchronization device and a second signal processing board;

the resonant light from any transceiver is transmitted to the first return reflector after passing through the first electro-optic modulator and the first gain medium, is reflected by the first return reflector according to the original path, and is transmitted to the transceiver after passing through the first gain medium and the first electro-optic modulator;

the resonant light transmitted by the first return reflector is transmitted to the first beam splitter and is divided into a beam of transmitted light and a beam of reflected light, the transmitted light is sent to the first photoelectric detector, and the reflected light is sent to the second photoelectric detector; the first photoelectric detector performs photoelectric conversion on input light, inputs an electric signal into a first signal processing board, the first signal processing board determines code words of all users according to a code table recorded in a register of the first signal processing board, and decodes a received signal by using the code words to restore information of all users; the second photoelectric detector carries out photoelectric conversion on input light and inputs an electric signal into the first synchronization device, the first synchronization device carries out real-time detection on a synchronization head in the electric signal, when the fact that the synchronization head is just finished is detected, a notice is sent to the second signal processing board, the second signal processing board generates sending information for each user after receiving the notice, code words of each user are determined according to a code table recorded in a register of the second signal processing board, the code words of each user are used for coding the sending information, coding results of each user are summed and then input into the first electro-optical modulator, and the first electro-optical modulator loads the input information onto resonance light and then sends the input information to a transceiver of each user.

Further, the transceiver comprises a second retro-reflector, a second gain medium, a second beam splitter, a third photodetector, a coupler, a third signal processing board, a second synchronization device and a second electro-optical modulator;

the resonance light from the base station is transmitted to the second beam splitter through the second electro-optic modulator, the second beam splitter splits the beam to obtain a beam of transmission light and a beam of reflection light, and the transmission light obtained through beam splitting is transmitted to the second retro-reflector through the second gain medium, then transmitted to the base station through the second gain medium, the second beam splitter and the second electro-optic modulator after being reflected;

after the third photoelectric detector performs photoelectric conversion on the signal, the output electric signal is input into the coupler, and the coupler divides the input electric signal into two paths of signals with equal or unequal power: one path of signal is input into a third signal processing board for demodulation, and the other path of signal is input into a second synchronous device; the third signal processing board demodulates the received information according to the pre-recorded code words to recover the information; the second synchronizer detects the input signal in real time, when the synchronization head of the electric signal is detected to be just finished, the information to be sent is generated and is coded by utilizing a pre-recorded code word, then the coded information is input into the second electro-optical modulator, and the second electro-optical modulator loads the received electric signal on resonance light and sends the resonance light to the base station.

Further, the first retro-reflector adopts a retro-reflector with the reflectivity of 90% and the transmissivity of 10%; the second retro-reflector adopts a retro-reflector with the reflectivity of 100% and the transmissivity of 0%.

Registers are integrated in the first signal processing board, the second signal processing board, the third signal processing board and the second synchronization device.

A multi-user resonance optical communication method based on optical code division multiple access comprises the following steps:

s1, a base station generates different and mutually orthogonal code words for each user, and stores the code words of each user to form a code table; the code word is an optical orthogonal code; saving code tables in registers of the first signal processing board and the second signal processing board; for each user, storing a code word corresponding to the user in a register of a third signal processing board in a transceiver of the user;

s2, the base station encodes the information sent to each user, sums the encoded data, inputs the summed data into a first electro-optical modulator for modulation and sending, and receives and decodes the signals from the transceiver;

and S3, after the transceiver of each user completes photoelectric conversion by using the second electro-optical modulator, decoding the received signals by using the pre-recorded code words to recover own signals, and coding and transmitting the signals to be transmitted.

Each frame data between the base station and the mobile terminal is composed of a synchronization header and information data.

The step S2 includes:

s201, transmitting resonance light transmitted by a first recovery reflector to a first beam splitter to be divided into a beam of transmission light and a beam of reflection light, transmitting the transmission light to a first photoelectric detector, and transmitting the reflection light to a second photoelectric detector;

s202, a first photoelectric detector performs photoelectric conversion on input light and inputs an electric signal into a first signal processing board, the first signal processing board determines code words of all users according to a code table recorded in a register in advance, and the code words are used for decoding received signals to restore information of all users;

s203, the second photoelectric detector performs photoelectric conversion on input light and inputs an electric signal into the first synchronization device, the first synchronization device performs real-time detection on a synchronization head in the electric signal, and when the fact that the synchronization head is just finished is detected, a notification is sent to the second signal processing board;

and S204, after receiving the notification, the second signal processing board generates sending information for each user, determines code words of each user according to a code table recorded in a register in advance, codes the sending information by using the code words of each user, sums the coding results of each user, inputs the sum into the first electro-optical modulator, and sends the input information to the transceiver of each user after the first electro-optical modulator loads the input information on the resonance light.

The step S3 includes:

s301, after photoelectric conversion is carried out on the signal by the third photoelectric detector, the output electric signal is input into a coupler, and the coupler divides the input electric signal into two paths of signals with equal or unequal power: one path of signal is input into a third signal processing board for demodulation, and the other path of signal is input into a second synchronous device;

s302, demodulating the received information by a third signal processing board according to the pre-recorded code words to restore the information;

and S303, the second synchronization device detects the input signal in real time, when the synchronization head of the electric signal is detected to be just finished, the information to be sent is generated and is coded by using a pre-recorded code word, and then the coded information is input into the second electro-optical modulator, and the second electro-optical modulator loads the received electric signal on resonance light and sends the resonance light to the base station.

The invention has the beneficial effects that: the invention realizes that a plurality of users can communicate with the transmitter at the same time without interference through the design of the coding and decoding structure. The method provides convenience for application of resonant optical communication in a multi-user scene.

Drawings

FIG. 1 is a schematic block diagram of the system of the present invention;

fig. 2 is a schematic diagram of a transceiver;

in the figure, 1-base station, 11-first retro-reflector, 12-first gain medium, 13-first electro-optical modulator, 14-first beam splitter, 15-first photodetector, 16-first signal processing board, 17-second photodetector, 18-first synchronization device, 19-second signal processing board, 2-moving terminal, 21-second retro-reflector, 22-second gain medium, 23-second beam splitter, 24-third photodetector, 25-coupler, 26-third signal processing board, 27-second synchronization device, 28-second electro-optical modulator.

Detailed Description

The technical solutions of the present invention are further described in detail below with reference to the accompanying drawings, but the scope of the present invention is not limited to the following.

As shown in fig. 1, a multi-user resonant optical communication system based on optical code division multiple access includes a base station 1 and a mobile terminal 2, where the mobile terminal includes transceivers located at different users; a resonant cavity is formed between the base station and each transceiver; in multi-user resonant optical communication based on optical code division multiple access, photons in free space can move back and forth between a retro-reflector of a base station and a retro-reflector of each mobile terminal until stable resonant light is formed in each resonant cavity.

The base station 1 comprises a first return reflector 11, a first gain medium 12, a first electro-optical modulator 13, a first beam splitter 14, a first photodetector 15, a first signal processing board 16, a second photodetector 17, a first synchronization device 18 and a second signal processing board 19;

the resonant light from any transceiver is transmitted to the first return reflector 11 after passing through the electro-optic modulator 13 and the first gain medium 12, is reflected by the first return reflector 11 according to the original path, and the reflected resonant light is transmitted to the transceiver after passing through the first gain medium 12 and the electro-optic modulator 13;

the resonance light transmitted by the first retro-reflector 11 is transmitted to the first beam splitter 14 to be split into a beam of transmission light and a beam of reflection light, the transmission light is sent to the first photoelectric detector 15, and the reflection light is sent to the second photoelectric detector 17; the first photodetector 15 performs photoelectric conversion on the input light and inputs an electric signal into the first signal processing board 16, the first signal processing board 16 determines a code word of each user according to a code table recorded in a register of the first signal processing board 16 in advance, and decodes a received signal by using the code word to restore information of each user; the second photoelectric detector 17 performs photoelectric conversion on the input light and inputs the electric signal into the first synchronization device 18, the first synchronization device 18 detects a synchronization head in the electric signal in real time, when the synchronization head is detected to be just finished, a notification is sent to the second signal processing board 19, the second signal processing board 19 generates sending information for each user after receiving the notification, code words of each user are determined according to a code table recorded in a register of the second signal processing board, the code words of each user are used for coding the sending information, coding results of each user are summed and then input into the first electro-optical modulator 13, and the first electro-optical modulator 13 loads the input information onto resonance light and then sends the input information to a transceiver of each user.

As shown in fig. 2, the transceiver comprises a second retro-reflector 21, a second gain medium 22, a second beam splitter 23, a third photodetector 24, a coupler 25, a third signal processing board 26, a second synchronization device 27 and a second electro-optical modulator 28;

the resonance light from the base station 1 is transmitted to the second beam splitter 23 through the second electro-optical modulator 28, the second beam splitter 23 splits the resonance light to obtain a beam of transmission light and a beam of reflection light, the transmission light obtained through beam splitting is transmitted to the second retro-reflector 21 through the second gain medium 22, and then is transmitted to the base station through the second gain medium 22, the second beam splitter 23 and the second electro-optical modulator 28 after being reflected;

after performing photoelectric conversion on the signal, the third photodetector 24 inputs the output electrical signal into a coupler 25, and the coupler divides the input electrical signal into two paths of signals with equal or unequal power: one signal is input to the third signal processing board 26 for demodulation, and the other signal is input to the second synchronization device 27; the third signal processing board 26 demodulates the received information according to the pre-recorded code to restore the information; the second synchronizer 27 detects the input signal in real time, when the synchronization head of the electrical signal is detected to be just finished, generates the information to be transmitted, encodes the information by using the pre-recorded code word, and inputs the encoded information into the second electro-optical modulator 28, and the second electro-optical modulator 28 loads the received electrical signal on the resonance light and transmits the electrical signal to the base station 1.

Further, the first retro-reflector 11 is a retro-reflector having a reflectivity of 90% and a transmittance of 10%; the second retro-reflector 21 is a retro-reflector having a reflectance of 100% and a transmittance of 0%. Registers are integrated in the first signal processing board 16, the second signal processing board 19, the third signal processing board 26 and the second synchronization means 27.

In the embodiment of the present application, when light passes through the first electro-optical modulator 13, if a signal is input to the first electro-optical modulator by the first synchronization device 19, electro-optical modulation is performed; if no signal is input, the light is directly output through the first electro-optical modulator without any processing; similarly, when light passes through the second electro-optical modulator 28, if a signal is input to the second electro-optical modulator by the second synchronization device 27, electro-optical modulation is performed, and if no signal is input, the light is directly output through the second electro-optical modulator without any processing.

In the embodiment of the present application, it should be noted that, for the first beam splitter 14 and the second beam splitter 23, the film on the front surface of the beam splitter is different from the film on the back surface of the beam splitter, and when light impinges on the film of the beam splitter from the front surface, the light is divided into two parts, namely, reflected light and transmitted light. And when light strikes the film of the beam splitter from the back, the light is completely transmitted. In fig. 1 to 2, the smooth side of the beam splitter represents the front side, and the slanted side represents the reverse side.

In order to solve the problem of multi-user communication in resonant optical communication, the invention designs a bidirectional multi-user resonant optical communication mode based on Optical Code Division Multiple Access (OCDMA). In this communication scheme, one round trip of resonant light between transceivers is taken as one frame of data, and by allocating mutually orthogonal code words to each user and encoding information transmitted to each user, it is ensured that a plurality of users communicate with the transmitter without interference at the same time. In a resonant optical communication system, the used code words are all unipolar code words consisting of 0 and 1;

because the product of two different optical orthogonal codes is 0, the user can obtain the signal only belonging to the user after multiplying the code word of the user by the code words of other users.

Based on the above encoding and decoding schematic diagram, a multi-user resonance optical communication method based on optical code division multiple access in the present application includes the following steps:

s1, a base station 1 generates different and mutually orthogonal code words (optical orthogonal codes) for each user, and stores the code words of each user to form a code table; saving the code tables in the registers of the first signal processing board 16 and the second signal processing board 19; for each user, storing the code word corresponding to the user in the register of the third signal processing board 26 in the transceiver of the user;

s2, the base station 1 encodes the information sent to each user, sums the encoded data, inputs the summed data into the first electro-optical modulator 13 for modulation and sending, and receives and decodes the signals from the transceiver;

and S3, after the transceiver of each user uses the second electro-optical modulator 28 to complete the photoelectric conversion, decoding the received signals by using the pre-recorded code words to recover own signals, and coding and transmitting the signals to be transmitted.

Each frame data between the base station 1 and the mobile terminal is composed of a synchronization header and information data.

The step S2 includes:

s201, transmitting the resonance light transmitted by the first recovery reflector 11 to the first beam splitter 14 to split the resonance light into a beam of transmission light and a beam of reflection light, sending the transmission light into the first photoelectric detector 15, and sending the transmission light into the second photoelectric detector 17 in a reflection mode;

s202, the first photoelectric detector 15 performs photoelectric conversion on input light and inputs an electric signal into the first signal processing board 16, the first signal processing board 16 determines code words of all users according to a code table recorded in a register in advance, and the code words are used for decoding received signals to restore information of all users;

s203, the second photoelectric detector 17 performs photoelectric conversion on the input light and inputs an electric signal into the first synchronization device 18, the first synchronization device 18 performs real-time detection on a synchronization head in the electric signal, and when the synchronization head is detected to be just finished, a notification is sent to the second signal processing board 19;

and S204, after receiving the notification, the second signal processing board 19 generates sending information for each user, determines code words of each user according to a code table recorded in a register in advance, codes the sending information by using the code words of each user, sums the coding results of each user, inputs the sum into the first electro-optical modulator 13, and sends the input information to the transceiver of each user after the first electro-optical modulator 13 loads the input information on resonant light.

The step S3 includes:

s301, after performing photoelectric conversion on the signal, the third photodetector 24 inputs an output electrical signal into the coupler 25, and the coupler divides the input electrical signal into two paths of signals with equal or unequal power: one signal is input to the third signal processing board 26 for demodulation, and the other signal is input to the second synchronization device 27;

s302, the third signal processing board 26 demodulates the received information according to the pre-recorded code words to restore the information;

and S303, the second synchronization device 27 detects the input signal in real time, when the synchronization head of the electric signal is detected to be just finished, the information to be sent is generated and is coded by using a pre-recorded code word, then the coded information is input into the second electro-optical modulator 28, and the second electro-optical modulator 28 loads the received electric signal on resonance light and sends the resonance light to the base station 1.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.