Tunable multi-carrier wireless communication system based on optical comb signal

Abstract

The utility model provides a tunable multi-carrier wireless communication system based on an optical comb signal, comprising a transmitting terminal unit used for generating an optical comb signal which comprises a plurality of optical signals with different frequencies; the wireless communication system further comprises more than two radio frequency remote units, each radio frequency remote unit communicates with the transmitting terminal unit through a pair of optical fibers, and the pair of optical fibers comprises an uplink optical fiber and a downlink optical fiber. Each radio frequency remote unit is provided with an optical splitter, the optical splitter receives an optical comb signal output by the transmitting terminal unit through a downlink optical fiber and outputs the optical comb signal to a photoelectric detector, and the photoelectric detector demodulates the optical comb signal and then outputs the demodulated optical comb signal to a plurality of rectangular filters; the filtering frequency of each rectangular filter is different from the filtering frequency of another rectangular filter, and signals output by the plurality of rectangular filters are output to the radio frequency combiner and are sent to the air by the radio frequency combiner through the antenna. And the production cost is low.

Description

Technical Field

[0001] This utility model relates to the field of wireless communication technology, specifically, to a tunable multicarrier wireless communication system based on optical comb signals. Background Technology

[0002] An optical comb signal is a signal generated by an optical frequency comb. The optical spectrum of an optical comb signal exhibits a frequency comb tooth-like distribution with equal spacing. Optical comb signals have high stability and accuracy in the frequency domain and have been increasingly applied to wireless communication systems.

[0003] Chinese invention patent application CN107222263A discloses a microwave photonic transceiver based on a coherent optical frequency comb. This transceiver generates a pair of coherent signal optical frequency combs and a local oscillator optical frequency comb through a seed light source module. These are then split into two paths by two beam splitters. For the transmitting module, one of the signal optical frequency combs is demultiplexed by a demultiplexing module, and the intermediate frequency signal to be transmitted is loaded through electro-optic modulation. The modulated signal optical frequency comb and one of the local oscillator optical frequency combs are combined, and a high-frequency transmission signal is obtained through photoelectric detection. For the receiving module, the other signal optical frequency comb is directly loaded with the received signal through an electro-optic modulator and sent to the signal input of an optical mixer. The other local oscillator optical frequency comb is input to the local oscillator input of the same optical mixer. The two orthogonal output optical signals of the optical mixer are then subjected to channel cutting and coherent detection, respectively.

[0004] However, existing microwave photonic transceivers have a one-to-one correspondence between the transmitting and receiving modules, with the optical comb signal generated by the transmitting module being directly transmitted into the air. Because both the transmitting and receiving modules require numerous complex components, especially the receiving module which needs to include an optical mixer, optical processing module, and coherence processing module, the overall structure of the microwave photonic transceiver is complex and production costs are high. Furthermore, the monolithic design of the transmitting module makes it difficult to meet the requirements for long-distance signal transmission. Summary of the Invention

[0005] The purpose of this invention is to provide a low-cost, tunable multicarrier wireless communication system based on optical comb signals.

[0006] To achieve the above objectives, the present invention provides a tunable multicarrier wireless communication system based on optical comb signals, comprising a transmitting terminal unit for generating optical comb signals, the optical comb signals containing multiple optical signals of different frequencies; the wireless communication system further comprises two or more radio frequency remote units, each of which communicates with the transmitting terminal unit via a pair of optical fibers, the pair of optical fibers including an uplink fiber and a downlink fiber; each radio frequency remote unit has a beam splitter, which receives the optical comb signal output from the transmitting terminal unit via the downlink fiber and outputs the optical comb signal to a photodetector, the photodetector demodulates the optical comb signal and outputs it to multiple rectangular filters, each rectangular filter having a different filtering frequency than the other rectangular filter, the signals output by the multiple rectangular filters are output to a radio frequency combiner, and the radio frequency combiner transmits the signal into the air via an antenna.

[0007] As can be seen from the above scheme, the tunable multicarrier wireless communication system based on optical comb signals is equipped with a transmitting terminal unit and multiple radio frequency remote units. The transmitting terminal unit can transmit multiple vector microwave signals modulated at different frequencies on a single optical carrier signal to multiple radio frequency remote units. The photodetectors of each radio frequency remote unit demodulate these microwave signals and obtain multiple microwave signals of different frequencies. Finally, the radio frequency combiner transmits these microwave signals into the air through the antenna.

[0008] Since the optical comb signal generated by the transmitting terminal unit can be transmitted over a long distance through the downlink optical fiber to the radio frequency remote unit, and then demodulated by the photodetector of the radio frequency remote unit, multiple vector microwave signals of different frequencies do not need strict frequency phase synchronization. This design can reduce the production cost of multi-carrier wireless communication systems and improve frequency efficiency.

[0009] In a preferred embodiment, the wireless communication system further includes a wavelength division multiplexer that receives the signal output from the optical splitter and outputs at least one optical signal to a backup light source.

[0010] Therefore, it can be seen that the backup of the light source is achieved by outputting one optical signal from the output end of the wavelength division multiplexer to the backup light source.

[0011] A further approach is to include a power regulator in the wireless communication system. The power regulator receives the digital baseband signal, adjusts its power, and then transmits it to the transmitting terminal unit via the uplink optical fiber.

[0012] As can be seen, the power regulator can adjust the power of the digital baseband signal so that the power of the digital baseband signal uploaded to the transmitting terminal unit meets the requirements for transmission and reception.

[0013] A further approach is to have the power regulator also receive one optical signal output from the wavelength division multiplexer. In this way, the power regulator can adjust the power of the digital baseband signal based on the optical signal output from the wavelength division multiplexer, thereby ensuring that the power of the output signal meets the reception requirements of the transmitting terminal unit.

[0014] A further approach is to connect a power amplifier to the output of the rectangular filter, and then use multiple power amplifiers to amplify the signal output from the rectangular filter before outputting it to the RF combiner.

[0015] Therefore, it can be seen that using a power amplifier to amplify the power of the microwave signal obtained by the rectangular filter increases the power of the transmitted microwave signal and improves the signal strength received by the mobile terminal.

[0016] A further approach is to have the same number of power amplifiers as the number of rectangular filters, with each power amplifier and rectangular filter configured in a one-to-one correspondence.

[0017] In this way, each power amplifier can amplify the power of the microwave signal output from a rectangular filter.

[0018] A further approach is to use a bandpass rectangular filter.

[0019] A further proposed solution is to use standard single-mode fiber for both the uplink and downlink optical fibers. Furthermore, the lengths of both the uplink and downlink optical fibers are over 10 kilometers.

[0020] Therefore, it can be seen that optical signals can be transmitted between the transmitting terminal unit and the radio frequency remote unit through long-distance single-mode optical fiber, allowing multiple radio frequency remote units to be arranged at a distance from the transmitting terminal unit, and multiple radio frequency remote units can transmit microwave signals independently of each other, thus meeting the requirements for long-distance transmission of microwave signals. Attached Figure Description

[0021] Figure 1 This is a structural diagram of an embodiment of the tunable multicarrier wireless communication system based on optical comb signals of this utility model.

[0022] Figure 2 This is a structural diagram of the radio frequency remote unit in an embodiment of the tunable multicarrier wireless communication system based on optical comb signals of this utility model.

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0024] This invention relates to a tunable multi-carrier wireless communication system based on optical comb signals. The system modulates multiple vector microwave signals of different frequencies onto a single optical carrier, transmits these signals over a long distance via a standard single-mode optical fiber, demodulates them in a radio frequency remote unit using a direct photodetector, and then transmits the demodulated microwave signals into the air via an antenna. This approach eliminates the need for strict frequency and phase synchronization of the multiple microwave signals, reducing equipment costs and improving frequency efficiency.

[0025] See Figure 1 This embodiment includes a transmitting terminal unit 10 and multiple radio frequency remote units 11, 21, and 31. The transmitting terminal unit 10 is connected to each of the radio frequency remote units 11, 21, and 31 by a pair of optical fibers. For example, the transmitting terminal unit 10 and the radio frequency remote unit 11 transmit optical signals via downlink fiber 12 and uplink fiber 13. Similarly, the transmitting terminal unit 10 and the radio frequency remote unit 21 transmit optical signals via downlink fiber 22 and uplink fiber 23, and the transmitting terminal unit 10 and the radio frequency remote unit 31 transmit optical signals via downlink fiber 32 and uplink fiber 33. Preferably, the downlink fibers 12, 22, and 32 and the uplink fibers 13, 23, and 33 are all standard single-mode fibers, and the length of each downlink fiber 12, 22, and 32 and the uplink fiber 13, 23, and 33 is at least 10 kilometers, and more preferably at least 30 kilometers. In this way, the transmitting terminal unit 10 and each radio frequency remote unit 11, 21, and 31 can be distributed at relatively far locations. Furthermore, since the optical comb signals received by each radio frequency remote unit 11, 21, and 31 are the same, the microwave signals obtained after demodulation by their respective photodetectors are also the same. This allows microwave signals of the same frequency to be transmitted from multiple different and far-away locations, meeting the communication needs in special scenarios.

[0026] The following description uses the radio frequency remote unit 11 as an example. The optical comb signal generated by the transmitting terminal unit 10 is transmitted to the radio frequency remote unit 11 through the downlink optical fiber 12. The optical comb signal contains multiple microwave signals of different frequencies. Preferably, the frequency interval between two adjacent microwave signals is the same.

[0027] See Figure 2The radio frequency remote unit 11 is equipped with a beam splitter 51. The beam splitter 51 receives the optical comb signal output from the receiving and transmitting terminal unit 10 through the downlink optical fiber 12 and outputs the optical comb signal to the photodetector 52. The photodetector 52 demodulates the received optical comb signal, and the demodulated signal contains multiple microwave signals of different frequencies. The demodulated signal is output to multiple rectangular filters. In this embodiment, there are seven rectangular filters, namely rectangular filters 61, 62, 63, 64, 65, 66, and 67. Each rectangular filter 61, 62, 63, 64, 65, 66, and 67 is a bandpass rectangular filter. Therefore, each rectangular filter can only output a signal that meets the specific frequency requirements. Preferably, the center frequencies of each rectangular filter 61, 62, 63, 64, 65, 66, and 67 are not the same. Specifically, since the optical comb signal output by the transmitting terminal unit 10 contains multiple microwave signals with different frequencies, each rectangular filter 61, 62, 63, 64, 65, 66, and 67 corresponds to a microwave signal of a specific frequency. That is, the filtering frequency of each rectangular filter is different from the filtering frequency of another rectangular filter. In this way, each rectangular filter 61, 62, 63, 64, 65, 66, and 67 can filter a microwave signal of a specific frequency, thereby outputting a microwave signal of a specific wavelength.

[0028] The radio frequency remote unit 11 also contains multiple power amplifiers 71, 72, 73, 74, 75, 76, and 77, from... Figure 2 As can be seen, the number of power amplifiers is equal to the number of rectangular filters. Since there are seven rectangular filters, there are also seven power amplifiers. Furthermore, the number of power amplifiers corresponds one-to-one with the number of rectangular filters; that is, each rectangular filter's output is connected to a power amplifier. For example, power amplifier 71 is connected to the output of rectangular filter 61, power amplifier 72 is connected to the output of rectangular filter 62, and so on.

[0029] Each power amplifier receives the microwave signal output from its corresponding rectangular filter, amplifies the power of the microwave signal, and outputs the amplified microwave signal to the RF combiner 80. The RF combiner 80 receives multiple microwave signals and then transmits them into the air via an antenna. (See previous section) Figure 1 Multiple radio frequency remote units 11, 21, and 31 can transmit their demodulated microwave signals into the air, and multiple mobile terminals 41, 42, 43, 44, 45, 46, and 47 can receive the microwave signals transmitted by radio frequency remote units 11, 21, and 31 in the air, thereby realizing microwave communication.

[0030] See Figure 2Within the radio frequency remote unit 11, there is also a wavelength division multiplexer 53. The wavelength division multiplexer 53 receives the signal output from the optical splitter 51. One signal output from the wavelength division multiplexer 53 is sent to the power conditioner 55. The power conditioner 55 also receives a digital baseband signal 56, adjusts the power of the digital baseband signal 56, and transmits the adjusted digital baseband signal 56 to the transmitting terminal unit 10 via the uplink optical fiber 13. Since the power conditioner 55 receives one signal output from the wavelength division multiplexer 53, it adjusts the power of the digital baseband signal 56 according to the received optical signal to ensure that the digital baseband signal transmitted to the uplink optical fiber 13 meets the receiving power requirements of the transmitting terminal unit 10.

[0031] In addition, one or more signals output by wavelength division multiplexer 53 are output to backup light source 54. Backup light source 54 can receive multiple optical signals of different frequencies from wavelength division multiplexer 53, and can provide backup light source for radio frequency remote unit 11.

[0032] Since the optical comb signal generated by the transmitting terminal unit 10 can be transmitted over a long distance through multiple downlink optical fibers to multiple radio frequency remote units 11, 21, and 31, and then demodulated by the photodetectors of the multiple radio frequency remote units 11, 21, and 31, multiple vector microwave signals of different frequencies do not need strict frequency phase synchronization. Therefore, this invention can reduce the production cost of multi-carrier wireless communication systems and improve frequency efficiency.

[0033] In addition, since multiple radio frequency remote units 11, 21, and 31 can be distributed in multiple different locations at a considerable distance, the usage requirements of scenarios that require distributed wireless signal transmission can be met.

[0034] Finally, it should be emphasized that the above are only preferred embodiments of the present utility model and are not intended to limit the present utility model. For those skilled in the art, the present utility model can have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A tunable multicarrier wireless communication system based on optical comb signals, comprising: A transmitting terminal unit is used to generate an optical comb signal, wherein the optical comb signal contains multiple optical signals of different frequencies; Its features are: The wireless communication system also includes two or more radio frequency remote units, each of which communicates with the transmitting terminal unit through a pair of optical fibers, including an uplink optical fiber and a downlink optical fiber. Each of the radio frequency remote units has a beam splitter, which receives the optical comb signal output by the transmitting terminal unit through the downlink optical fiber and outputs the optical comb signal to a photodetector. The photodetector demodulates the optical comb signal and outputs it to multiple rectangular filters. The filtering frequency of each rectangular filter is different from that of another rectangular filter. The signals output by the multiple rectangular filters are output to a radio frequency combiner, which transmits them into the air through an antenna.

2. The tunable multi-carrier wireless communication system based on optical comb signals according to claim 1, characterized in that: The wireless communication system also includes a wavelength division multiplexer that receives the signal output from the optical splitter and outputs at least one optical signal to a backup light source.

3. The tunable multi-carrier wireless communication system based on optical comb signals according to claim 2, characterized in that: The wireless communication system also includes a power conditioner, which receives a digital baseband signal, adjusts the power of the digital baseband signal, and then transmits it to the transmitting terminal unit through the uplink optical fiber.

4. The tunable multi-carrier wireless communication system based on optical comb signals according to claim 3, characterized in that: The power regulator also receives one optical signal output from the wavelength division multiplexer.

5. The tunable multi-carrier wireless communication system based on optical comb signals according to any one of claims 1 to 4, characterized in that: The output of the rectangular filter is connected to a power amplifier, and multiple power amplifiers amplify the signal output from the rectangular filter before outputting it to the radio frequency combiner.

6. The tunable multi-carrier wireless communication system based on optical comb signals according to claim 5, characterized in that: The number of power amplifiers is equal to the number of rectangular filters, and the power amplifiers and rectangular filters are configured in a one-to-one correspondence.

7. The tunable multi-carrier wireless communication system based on optical comb signals according to any one of claims 1 to 4, characterized in that: The rectangular filter is a bandpass rectangular filter.

8. The tunable multi-carrier wireless communication system based on optical comb signals according to any one of claims 1 to 4, characterized in that: Both the uplink fiber and the downlink fiber are standard single-mode fibers.

9. The tunable multi-carrier wireless communication system based on optical comb signals according to claim 8, characterized in that: Both the uplink fiber and the downlink fiber are over 10 kilometers in length.

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