Time-division duplex (TDD) timing signal broadcasting method and system

Abstract

A time-division duplex (TDD) timing signal broadcasting method includes the following steps of: a first device receiving a radio frequency signal sent by a base station; the first device capturing a TDD timing signal and a downlink signal from the radio frequency signal, wherein the downlink signal has a downlink frequency range; the first device modulating the TDD timing signal on a chosen carrier signal to form a controlling carrier signal, wherein the controlling carrier signal has a carrier signal frequency range, and the downlink frequency range and the carrier signal frequency range are staggered from each other; and the first device sending the controlling carrier signal and the downlink signal to at least one second device through at least one coaxial cable or optical fiber.

Description

Technical Field

[0001] This invention relates to the field of communications, and more particularly to a time-division duplex timing signal broadcasting method and system. Prior Technology

[0002] In recent years, various communication devices have been widely used in daily life. Taking smartphones as an example, when a smartphone transmits data or signals, it communicates with the base station via uplink and downlink signals, all through a wireless channel. However, the user's location and environmental factors can affect the transmission quality of the wireless channel, especially when the user is indoors or in the basement of a building (such as an office building, residence, hotel, or hospital). In such cases, the base station's signal transmission is severely obstructed, leading to poor communication quality or even signal loss. Therefore, existing technology has developed distributed antenna systems deployed within buildings, using passive antenna elements to emit signals for the user's smartphone to communicate and transmit, thereby solving the problem of indoor communication signal coverage.

[0003] Generally, existing distributed antenna systems determine the uplink or downlink transmission mode based on the Time Division Duplex (TDD) timing signal in the radio frequency signal transmitted by the base station to transmit uplink and downlink signals. Furthermore, existing distributed antenna systems can extract the TDD timing signal from the radio frequency signal transmitted by the base station or directly obtain the TDD timing signal through the communication module. However, in existing technologies, when the distributed antenna system obtains the TDD timing signal and transmits it to the passive antenna element, the passive antenna element needs to determine the transmission mode of the current TDD timing signal again. In other words, the time when the system obtains the TDD timing signal and the time when the passive antenna element switches to the uplink / downlink transmission mode will cause errors and delays, leading to incomplete signal reception or transmission. Furthermore, when the distributed antenna system contains multiple passive antenna elements, each passive antenna element may also experience asynchronous mode switching due to different timing of transmission mode determination, resulting in interference between passive antenna elements and thus reducing signal transmission efficiency. Summary of the Invention

[0004] In view of this, one aspect of the present invention provides a time-division duplex (TDD) timing signal broadcasting method to solve the problems of the prior art. In a specific embodiment, the time-division duplex (TDD) timing signal broadcasting method includes the following steps: a first device receives a radio frequency signal emitted by a base station; the first device extracts a TDD timing signal and a downlink signal from the radio frequency signal, wherein the downlink signal has a downlink signal frequency range; the first device modulates the TDD timing signal to a specific carrier to form a control carrier, wherein the control carrier has a carrier frequency range, and the carrier frequency range is offset from the downlink signal frequency range; and the first device transmits the control carrier and the downlink signal to at least one second device through at least one coaxial cable or optical fiber.

[0005] The step of transmitting a control carrier and downlink signal from the first device to at least one second device via at least one coaxial cable or optical fiber further includes the following steps: the first device transmits the control carrier and downlink signal to a relay device via optoelectronic transmission; and the relay device transmits the control carrier and downlink signal to at least one second device via at least one coaxial cable or optical fiber.

[0006] The time-division duplex (TDD) timing signal broadcasting method further includes the following steps: at least one second device analyzes the control carrier to generate a TDD timing signal; and at least one second device restores the downlink signal to a radio frequency signal and transmits the radio frequency signal according to the TDD timing signal.

[0007] The method further includes the following steps after the step of analyzing and controlling the carrier to generate a TDD timing signal by at least one second device: at least one second device receives a device signal from at least one third device and generates an uplink signal based on the device signal, wherein the uplink signal has an uplink signal frequency range and the uplink signal frequency range is offset from the carrier frequency range; and at least one second device transmits the uplink signal to the first device based on the TDD timing signal and through at least one coaxial cable.

[0008] The carrier frequency range does not overlap with the downlink signal frequency range or the uplink signal frequency range.

[0009] The modulation method is one of amplitude shift modulation (ASK), frequency shift modulation (FSK), and phase shift modulation (PSK).

[0010] Another aspect of the present invention provides a time-division duplex (TDD) timing signal broadcasting system to address the problems of the prior art.

[0011] In one embodiment, a time-division duplex (TDD) timing signal broadcasting system includes a first device and at least one second device. The first device is communicatively connected to a base station, and the at least one second device is coupled to the first device via at least one coaxial cable or optical fiber. The first device includes a communication interface, a signal determination unit, a signal modulation unit, and a transmission unit. The communication interface is used to receive radio frequency signals emitted by the base station. The signal determination unit is used to extract a TDD timing signal and a downlink signal from the radio frequency signals, wherein the downlink signal has a downlink signal frequency range. The signal modulation unit is used to modulate the TDD timing signal to a specific carrier to form a control carrier, wherein the control carrier has a carrier frequency range, and the carrier frequency range is offset from the downlink signal frequency range. The transmission unit is used to transmit the control carrier and the downlink signal. The at least one second device is used to receive the control carrier and the downlink signal.

[0012] The time-division duplex (TDD) timing signal broadcasting system further includes a relay device that communicates with a first device and at least one second device. The first device transmits a control carrier and downlink signals to the relay device via an optical fiber, and the relay device transmits a control carrier and downlink signals to at least one second device via at least one coaxial cable.

[0013] In this embodiment, at least one second device is used to analyze the control carrier to generate a TDD timing signal and restore the downlink signal to an RF signal, and at least one second device transmits the RF signal according to the TDD timing signal.

[0014] In this configuration, at least one second device is used to receive device signals from at least one third device and generate an uplink signal based on the device signals, and transmit the uplink signal to the first device via at least one coaxial cable according to a TDD timing signal. The uplink signal has an uplink signal frequency range, and the uplink signal frequency range is offset from the carrier frequency range.

[0015] The signal modulation unit modulates the TDD timing signal using one of the following: amplitude offset modulation (ASK), frequency offset modulation (FSK), and phase offset modulation (PSK).

[0016] In summary, the Time Division Duplex (TDD) timing signal broadcasting method and system of the present invention can use a first device to single-detect and determine the TDD timing signal of the base station and broadcast the modulated control carrier to all second devices. This eliminates the need for each second device to extract the TDD timing signal and determine the communication mode from the radio frequency signal, thus avoiding accumulated errors and delays caused by multiple detections. Furthermore, since the carrier frequency range of the control carrier differs from the downlink signal frequency range and the radio frequency signal frequency, and the control carrier is not affected by the downlink signal, the second devices can switch communication modes more accurately and synchronously according to the control carrier, thereby avoiding interference between the second devices. Simple Explanation of the Diagram

[0017]

[0018] Figure 1 is a flowchart illustrating the steps of a time-division duplex (TDD) timing signal broadcasting method according to a specific embodiment of the present invention.

[0019] Figure 2 is a functional block diagram illustrating a time-division duplex (TDD) timing signal broadcasting system according to a specific embodiment of the present invention.

[0020] Figures 3A to 3D illustrate waveforms of the control carrier according to various specific embodiments of the present invention.

[0021] Figure 4 is a schematic diagram illustrating the architecture of a time-division duplex (TDD) timing signal broadcasting system according to a specific embodiment of the present invention.

[0022] Figure 5 is a flowchart illustrating the steps of a time-division duplex (TDD) timing signal broadcasting method according to a specific embodiment of the present invention.

[0023] Figure 6 is a flowchart illustrating the steps of a time-division duplex (TDD) timing signal broadcasting method according to a specific embodiment of the present invention.

[0024] Figure 7 is a schematic diagram illustrating the architecture of a time-division duplex (TDD) timing signal broadcasting system according to a specific embodiment of the present invention. Implementation

[0025] To make the advantages, spirit, and features of the present invention easier and clearer to understand, detailed descriptions and discussions will follow with reference to specific embodiments and the accompanying drawings. It is important to note that these specific embodiments are merely representative examples of the present invention, and the specific methods, apparatus, conditions, materials, etc., exemplified are not intended to limit the present invention or the corresponding specific embodiments.

[0026] The indefinite articles “a,” “an,” and “an” preceding the apparatus or element of this invention do not impose a limit on the quantity (i.e., the number of times) of the apparatus or element. Therefore, “a” should be interpreted as including one or at least one, and the singular form of apparatus or element also includes the plural form, unless the quantity clearly refers to the singular form.

[0027] Please refer to Figure 1. Figure 1 is a flowchart illustrating the steps of a time-division duplex (TDD) timing signal broadcasting method according to a specific embodiment of the present invention. As shown in Figure 1, in this specific embodiment, the time-division duplex (TDD) timing signal broadcasting method includes the following steps: Step S1: A first device receives a radio frequency signal emitted by a base station; Step S2: The first device extracts a TDD timing signal and a downlink signal from the radio frequency signal, wherein the downlink signal has a downlink signal frequency range; Step S3: The first device modulates the TDD timing signal to a specific carrier to form a control carrier, wherein the control carrier has a carrier frequency range, and the carrier frequency range is offset from the downlink signal frequency range; and Step S4: The first device transmits the control carrier and the downlink signal to at least one second device through at least one coaxial cable.

[0028] In step S1, the base station can be a fixed, high-power, bidirectional transmitter capable of emitting radio frequency (RF) signals. In practice, the RF signal can be a 4G / 5G Time Division Duplex (TDD) signal, but is not limited to this; the RF signal can also be a higher frequency signal. The RF signal can have a specific RF signal frequency. The first device can be a main signal processing device and has a wired communication connection to the base station to receive the RF signals emitted by the base station.

[0029] In step S2, the first device can extract the TDD timing signal and the downlink signal from the radio frequency signal. The TDD timing signal determines the time slot for uplink and downlink communication. The uplink communication mode signal represents the time sequence signal for the base station to receive data, and the downlink communication mode signal represents the time sequence signal for the base station to transmit data. In practice, the radio frequency of the radio frequency signal may include, but is not limited to, the downlink signal frequency range. The first device may also down-frequency and / or shift the radio frequency signal to generate the downlink signal, so that the downlink signal frequency range is different from the radio frequency signal frequency, and that the downlink signal can be transmitted within a predetermined or specific signal frequency range.

[0030] In step S3, after the first device extracts the TDD timing signal, it can perform signal modulation on the TDD timing signal to form a control carrier signal. The modulation method can be amplitude offset modulation (ASK), frequency offset modulation (FSK), phase offset modulation (PSK), or digital signal conversion, but is not limited to these. In practical applications, the first device modulates the TDD timing signal to a specific carrier to form a control carrier. The carrier frequency range of the control carrier differs from the radio frequency signal frequency.

[0031] In step S4, the second device may be an active antenna unit (AAU) or a communication module formed by a remote radio unit (RRU) and an antenna. In practice, the first device may be communicatively connected to one or more second devices. After the first device generates a control carrier, it can simultaneously and synchronously transmit the control carrier to one or more second devices. Furthermore, when the first device determines that the current TDD timing signal (or control carrier) is a downlink communication mode signal, it can transmit both the control carrier and the downlink signal to one or more second devices.

[0032] Please refer to Figures 1 and 2 together. Figure 2 is a functional block diagram illustrating a time-division duplex (TDD) timing signal broadcasting system 1 according to a specific embodiment of the present invention. The steps of Figure 1 can be performed through the time-division duplex (TDD) timing signal broadcasting system 1 of Figure 2. As shown in Figure 2, the time-division duplex (TDD) timing signal broadcasting system 1 includes a first device 11 and a plurality of second devices 12. The first device 11 is communicatively connected to a base station BS and communicatively coupled to the plurality of second devices 12. The first device 11 includes a communication interface 111, a signal determination unit 112, a signal modulation unit 113, and a transmission unit 114. In practice, the signal determination unit 112 and the signal modulation unit 113 can be integrated into a single processing chip (e.g., CPU), or they can be integrated into different chips on a circuit board.

[0033] In this specific embodiment, the communication interface 111 is used to receive radio frequency signals emitted by the base station (BS). In practice, the base station (BS) can communicate with the communication interface 111 of the first device 11 via a cable. The signal determination unit 112 is used to extract TDD timing signals from the radio frequency signals. The signal modulation unit 113 is used to modulate the TDD timing signals to form a control carrier. The transmission unit 114 is used to send the control carrier and downlink signals to the second device 12. A plurality of second devices 12 can be communicatively connected to the transmission unit 114 of the first device 11 via at least one coaxial cable 14 to receive the control carrier and downlink signals.

[0034] Furthermore, in this specific embodiment, the timing control carrier frequency range and the downlink signal frequency range are staggered. The signal modulation unit 113 can modulate the TDD timing signal captured by the signal judgment unit 112 so that the resulting control carrier frequency range differs from the downlink signal frequency range, thereby avoiding mutual interference between the control carrier and the downlink signal. In a preferred embodiment, the carrier frequency range is smaller than the downlink signal frequency range, and the carrier frequency range can be a low-frequency range to reduce signal attenuation.

[0035] Please refer to Figures 2, 3A to 3D. Figures 3A to 3D illustrate the waveforms of the control carrier according to various embodiments of the present invention. Specifically, Figure 3A shows the waveform of the control carrier after amplitude offset modulation (ASK), Figure 3B shows the waveform of the control carrier after frequency offset modulation (FSK), Figure 3C shows the waveform of the control carrier after phase offset modulation (PSK), and Figure 3D shows the waveform of the control carrier after digital signal conversion. In practice, the signal modulation unit 113 can generate the control carrier according to various modulation methods and the uplink and downlink communication mode signals in the TDD timing signal. Taking Figure 3A as an example, the downlink communication mode signal is represented by a band with a larger waveform amplitude, and the uplink communication mode signal is represented by a band with a smaller waveform amplitude. Taking Figure 3B as an example, the downlink communication mode signal is represented by a band with a higher waveform frequency, and the uplink communication mode signal is represented by a band with a lower waveform frequency. Taking Figure 3C as an example, the downlink communication mode signal is represented by a waveform with a first phase, and the uplink communication mode signal is represented by a waveform with a second phase. Taking Figure 3D as an example, the downlink communication mode signal is represented by a band with a digital signal of "1", and the uplink communication mode signal is a band with a digital signal of "0". It is worth noting that in practical applications, the waveforms corresponding to the uplink and downlink communication mode signals can be determined according to the user's design or requirements.

[0036] Please refer to Figures 2, 4, and 5 together. Figure 4 is a schematic diagram illustrating the architecture of a time-division duplex (TDD) timing signal broadcasting system 1 according to a specific embodiment of the present invention. Figure 5 is a flowchart illustrating the steps of a time-division duplex (TDD) timing signal broadcasting method according to a specific embodiment of the present invention. Figure 4 shows one implementation of the time-division duplex (TDD) timing signal broadcasting system 1 of Figure 2. Figure 5 shows further steps of Figure 1, and steps S1 to S4 in Figure 5 are substantially the same as those in Figure 1, and will not be described again here. The steps in Figure 5 can be achieved by the time-division duplex (TDD) timing signal broadcasting system 1 of Figures 2 and 4. The time-division duplex (TDD) timing signal broadcasting system 1 of the present invention can be applied to a passive distributed antenna system architecture (Passive DAS). As shown in Figure 4, in this specific embodiment, the Time Division Duplex (TDD) timing signal broadcasting system 1 includes one first device 11 and four second devices (12A to 12D), and the coaxial cable 14 between the first device 11 and the second devices (12A to 12D) is the line of a passive distributed antenna system. The coaxial cable 14 may contain multiple nodes, and the second devices (12A to 12D) are respectively disposed on the nodes. After the first device 11 generates a control carrier according to the radio frequency signal transmitted by the base station BS, the first device 11 can simultaneously and synchronously transmit the control carrier to the second devices (12A to 12D) at each node through the coaxial cable 14. It is worth noting that in practice, the number of second devices is not limited to the number shown in Figure 4, and can be determined according to requirements or design.

[0037] Therefore, the Time Division Duplex (TDD) timing signal broadcasting system of the present invention can determine the TDD timing signal of the base station by a single detection by the first device and broadcast the modulated control carrier to all second devices. This eliminates the need for each second device to extract the TDD timing signal and determine the communication mode from the radio frequency signal, thus avoiding accumulated errors and delays caused by multiple detections. Furthermore, since the carrier frequency range of the control carrier differs from the downlink signal frequency range and the radio frequency signal frequency, and the control carrier is not affected by the downlink signal, the second devices can switch communication modes more accurately and synchronously according to the control carrier, thereby avoiding interference between the second devices.

[0038] As shown in Figure 5, the Time Division Duplex (TDD) timing signal broadcasting method further includes the following steps: Step S5: At least one second device analyzes the control carrier to generate a TDD timing signal; Step S6: At least one second device restores the downlink signal to an RF signal and transmits the RF signal according to the TDD timing signal. Furthermore, after step S5, the method further includes the following steps: Step S7: At least one second device receives a device signal from at least one third device and generates an uplink signal according to the device signal, wherein the uplink signal has an uplink signal frequency range, and the uplink signal frequency range is offset from the carrier frequency range; and Step S8: At least one second device transmits the uplink signal to the first device according to the TDD timing signal and through at least one coaxial cable.

[0039] As shown in Figures 4 and 5, in step S5, the second device (12A to 12D) may include an analysis and processing chip. When the second device (12A to 12D) receives a control carrier, the analysis and processing chip can modulate the control carrier back into a TDD timing signal to obtain the timing of the uplink communication mode signal and the downlink communication mode signal.

[0040] In step S6, when the analysis and processing chip of the second device (12A to 12D) determines that the current TDD timing signal is a downlink communication mode signal, the second device (12A to 12D) can restore the downlink signal transmitted by the first device 11 to the same radio frequency signal emitted by the base station, and then emit the radio frequency signal through the antenna in a signal range R.

[0041] In step S7, taking the second device 12D as an example, when the analysis and processing chip of the second device 12D determines that the current TDD timing signal is an uplink communication mode signal, the antenna of the second device 12D can receive the device signal of the third device 13 located in the signal range R. The third device 13 can be a user device with data communication transmission function, such as a mobile phone, laptop, or tablet, and can communicate with the second device 12D wirelessly. The device signal can contain data to be transmitted to the base station BS, and the device signal can have a device signal frequency. Further, the second device 12D performs down-frequency and / or frequency-shifting processing on the device signal to generate an uplink signal with an uplink signal frequency, so that the uplink signal frequency range is different from the device signal frequency, and so that the uplink signal can be transmitted within a predetermined or specific signal frequency range.

[0042] In step S8, after the second device 12D generates the uplink signal of the third device 13, the second device 12D can transmit the uplink signal to the first device 11 through the coaxial cable 14, and then the first device 11 can transmit the uplink signal to the base station BS.

[0043] It is worth noting that in this specific embodiment, the uplink signal frequency range, carrier frequency range, and downlink signal frequency range are staggered and do not overlap, and the carrier frequency range is smaller than both the downlink and uplink signal frequency ranges, but this is not the only practical limitation. Therefore, the first device and the second device will not interfere with each other when transmitting downlink signals, uplink signals, and control carriers. Furthermore, in one specific embodiment, the analysis and processing chip of the second device can also directly determine and obtain the timing of the uplink communication mode signal and the downlink communication mode signal based on the control carrier transmitted by the first device, and send downlink signals to the third device and receive device signals from the third device according to the control carrier.

[0044] The time-division duplex (TDD) timing signal broadcasting system of the present invention can be in other forms besides the aforementioned specific embodiments. Please refer to Figures 6 and 7 together. Figure 6 is a flowchart illustrating the steps of a time-division duplex (TDD) timing signal broadcasting method according to a specific embodiment of the present invention. Figure 7 is a schematic diagram illustrating the architecture of a time-division duplex (TDD) timing signal broadcasting system 2 according to a specific embodiment of the present invention. Figure 6 shows further steps of Figure 1, and steps S1 to S3 in Figure 6 are substantially the same as those in Figure 1, and will not be described again here. The steps in Figure 6 can be achieved by the time-division duplex (TDD) timing signal broadcasting system 2 in Figure 7. As shown in Figures 6 and 7, the difference between this specific embodiment and the aforementioned specific embodiments is that the time-division duplex (TDD) timing signal broadcasting system 2 of this specific embodiment further includes a relay device 25, located between the first device 21 and the second devices (22A to 22D) and communicatively connected to the first device 21 and the second devices (22A to 22D). Furthermore, step S4 of the time-division duplex (TDD) timing signal broadcasting method in Figure 1 further includes the following steps: step S41: the first device 21 transmits the control carrier and downlink signal to the relay device 25 by photoelectric transmission; and step S42: the relay device 25 transmits the control carrier and downlink signal to the second device (22A to 22D) through the coaxial cable 24.

[0045] In step S41, the time-division duplex (TDD) timing signal broadcasting system 2 may include an optical fiber 26 connecting the first device 21 and the relay device 25. In practice, the optical fiber 26 may include a first optical fiber 261 and a second optical fiber 262. The first device 21 may transmit control carrier and downlink signals to the relay device 25 through the first optical fiber 261. In step S42, the relay device 25 may then transmit the control carrier and downlink signals to the second devices (22A to 22D) through the coaxial cable 24.

[0046] Similarly, relay device 25 can receive the uplink signal generated by third device 23 via coaxial cable 24, and can then transmit the uplink signal to first device 21 via second optical fiber 262. In practical applications, the first device can connect to two or more relay devices, and each relay device can connect to a passive distributed antenna system architecture.

[0047] In summary, the Time Division Duplex (TDD) timing signal broadcasting method and system of the present invention can use a first device to single-detect and determine the TDD timing signal of the base station and broadcast the modulated control carrier to all second devices. This eliminates the need for each second device to extract the TDD timing signal and determine the communication mode from the radio frequency signal, thus avoiding accumulated errors and delays caused by multiple detections. Furthermore, since the carrier frequency range of the control carrier differs from the downlink signal frequency range and the radio frequency signal frequency, and the control carrier is not affected by the downlink signal, the second devices can switch communication modes more accurately and synchronously according to the control carrier, thereby avoiding interference between the second devices.

[0048] The detailed description of the preferred embodiments above is intended to more clearly illustrate the features and spirit of the present invention, and is not intended to limit the scope of the invention to the preferred embodiments disclosed above. Rather, the aim is to cover various modifications and equivalent arrangements within the scope of the patent claims made by this invention. Therefore, the scope of the patent claims made by this invention should be interpreted in the broadest possible sense based on the foregoing description, so as to cover all possible modifications and equivalent arrangements.

[0049] 1, 2: Time-Division Duplex (TDD) Sequential Signal Broadcasting System

[0050] 11, 21: First device

[0051] 111: Communication Interface

[0052] 112: Signal Judgment Unit

[0053] 113: Signal Modulation Unit

[0054] 114: Transmission Unit

[0055] 13, 23: Third device

[0056] 14, 24: Coaxial cable

[0057] 12, 12A to 12D, 22A to 22D: Second device

[0058] 25: Relay device

[0059] 26: Fiber optic

[0060] 261: First optical fiber

[0061] 262: Second optical fiber

[0062] BS: Base Station

[0063] R: Pre-defined signal range

[0064] S1~S8, S41~S42: Steps

Claims

1. A time-division duplex (TDD) timing signal broadcasting method, comprising the following steps: a first device receiving a radio frequency signal emitted by a base station; the first device extracting a TDD timing signal and a downlink signal from the radio frequency signal, wherein the downlink signal has a downlink signal frequency range; the first device modulating the TDD timing signal to form a control carrier, wherein the control carrier has a carrier frequency range, and the carrier frequency range is offset from and does not overlap with the downlink signal frequency range; the first device transmitting the control carrier and the downlink signal to at least one second device via at least one coaxial cable; the at least one second device analyzing the control carrier to generate the TDD timing signal; and the at least one second device restoring the downlink signal to the radio frequency signal, and transmitting the radio frequency signal according to the TDD timing signal.

2. The time-division duplex (TDD) timing signal broadcasting method as described in claim 1, wherein the step of the first device transmitting the control carrier and the downlink signal to at least one second device via at least one coaxial cable further includes the following steps: the first device transmitting the control carrier and the downlink signal to a relay device by photoelectric transmission; and the relay device transmitting the control carrier and the downlink signal to the at least one second device via the at least one coaxial cable.

3. The time-division duplex (TDD) timing signal broadcasting method as described in claim 1, further comprising the steps of: the at least one second device receiving a device signal from at least one third device and generating an uplink signal based on the device signal, wherein the uplink signal has an uplink signal frequency range and the uplink signal frequency range is offset from the carrier frequency range; and the at least one second device transmitting the uplink signal to the first device based on the TDD timing signal and through the at least one coaxial cable.

4. The time-division duplex (TDD) timing signal broadcasting method as described in claim 1, wherein the modulation method is one of amplitude offset modulation (ASK), frequency offset modulation (FSK), and phase offset modulation (PSK).

5. A time-division duplex (TDD) timing signal broadcasting system includes: a first device communicatively connected to a base station, the first device comprising: a communication interface for receiving a radio frequency signal emitted by the base station; a signal determination unit for extracting a TDD timing signal and a downlink signal from the radio frequency signal, wherein the downlink signal has a downlink signal frequency range; a signal modulation unit for modulating the TDD timing signal to form a control carrier, wherein the control carrier has a carrier frequency range, and the carrier frequency range is offset from and does not overlap with the downlink signal frequency range; a transmission unit for transmitting the control carrier and the downlink signal; and at least one second device communicatively coupled to the first device via at least one coaxial cable and for receiving the control carrier and the downlink signal, the at least one second device for analyzing the control carrier to generate the TDD timing signal and restoring the downlink signal to the radio frequency signal, and the at least one second device for transmitting the radio frequency signal according to the TDD timing signal.

6. The time-division duplex (TDD) timing signal broadcasting system as described in claim 5 further includes a relay device communicatively connecting the first device and the at least one second device, wherein the first device transmits the control carrier and the downlink signal to the relay device via an optical fiber, and the relay device transmits the control carrier and the downlink signal to the at least one second device via the at least one coaxial cable.

7. A time-division duplex (TDD) timing signal broadcasting system as described in claim 5, wherein the at least one second device is configured to receive a device signal from at least one third device and generate an uplink signal based on the device signal, and transmit the uplink signal to the first device via the at least one coaxial cable based on the TDD timing signal, wherein the uplink signal has an uplink signal frequency range, and the uplink signal frequency range is offset from the carrier frequency range.

8. A time-division duplex (TDD) timing signal broadcasting system as described in claim 5, wherein the signal modulation unit modulates the TDD timing signal using one of amplitude offset modulation (ASK), frequency offset modulation (FSK), and phase offset modulation (PSK).

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