A distributed antenna system

Abstract

This invention discloses a distributed antenna system, comprising: a base station, and at least one wireless signal coverage device cascaded via a radio frequency cable; the base station is connected to a first-level wireless signal coverage device via a radio frequency cable and transmits the base station radio frequency signal to the first-level wireless signal coverage device; each level of the wireless signal coverage device opens an uplink radio frequency link or a downlink radio frequency link according to the control signal sent by the base station, and amplifies the radio frequency signal.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, and in particular relates to a distributed antenna system. Background Technology

[0002] The rapid development of wireless communication technology has led to increasingly scarce spectrum resources, while the demand for communication bandwidth is growing daily. During the deployment of wireless systems, situations often arise where a single base station cannot cover all areas due to environmental limitations. Examples include signal coverage scenarios such as multiple rooms on the same floor or the need to increase the number of base stations in a railway station due to obstruction between trains. However, increasing the number of base stations can introduce co-channel interference within the system, leading to a decline in communication quality.

[0003] Common passive indoor distribution systems consist of passive components such as combiners, couplers, power distribution units, antennas, and feeders, and have the following drawbacks:

[0004] 1) Passive components have relatively fixed frequencies, which makes it difficult to upgrade from one frequency band to another;

[0005] 2) When expanding from the current 1x1 system to 2x2, 4x4, etc., the cabling scheme is very complex;

[0006] 3) Since passive indoor distribution transmission does not amplify the signal and suffers from significant losses, for high-frequency systems (such as the current 5G system), the terminal's transmit power is generally not very high. As a result, after the passive indoor distribution system passes through the transmission loss, the power consumption of the terminal's transmit power reaching the base station is very low, which affects the system's uplink communication and may even cause communication interruption. Summary of the Invention

[0007] In view of this, the present invention proposes a low-cost and easy-to-deploy distributed antenna system, which is suitable for scenarios where a single base station cannot achieve signal coverage and multiple base stations need to be added. It can expand the coverage of a single base station, while ensuring signal coverage and guaranteeing the system's communication bandwidth. Moreover, it is inexpensive and easy to implement.

[0008] A distributed antenna system, comprising:

[0009] A base station, and at least one wireless signal coverage device cascaded via a radio frequency cable;

[0010] The base station is connected to the first-level wireless signal coverage device via an RF cable and transmits the base station's RF signal to the first-level wireless signal coverage device.

[0011] The base station outputs control signals to various levels of wireless signal coverage devices, and the control signals are used to indicate the uplink and downlink operation periods of the base station signal;

[0012] The wireless signal coverage devices at each level open the uplink or downlink radio frequency link according to the control signal and amplify the radio frequency signal.

[0013] The wireless signal coverage device includes:

[0014] The power distribution unit splits the radio frequency signal input to the local wireless signal coverage device into two paths: one path is input to the local radio frequency signal processing unit, and the other path is transmitted to the next level wireless signal coverage device.

[0015] The control unit receives control signals sent by the base station and sends the control signals to the radio frequency signal processing unit; it also transmits commands and performs data interaction with the base station through interface signals.

[0016] The radio frequency signal processing unit, according to the control signal, turns on the uplink signal amplification radio frequency circuit and turns off the downlink signal amplification circuit, or turns on the downlink signal amplification radio frequency circuit and turns off the uplink signal amplification radio frequency circuit; and amplifies the uplink or downlink radio frequency signal.

[0017] The base station is connected to the control unit of wireless signal coverage devices at all levels;

[0018] The first output of the power distribution unit is connected to the radio frequency signal processing unit of the same level, and the second output is connected to the input of the power distribution unit of the next level wireless signal coverage device through a radio frequency cable. The wireless signal coverage devices at each level are cascaded through radio frequency cables to extend the radio frequency signal of the base station.

[0019] The radio frequency signal processing unit includes:

[0020] A downlink radio frequency signal amplification circuit consisting of a first link control switch, a downlink low-noise amplifier, a downlink automatic gain control unit, a downlink power amplifier, and a second link control switch connected in sequence;

[0021] An uplink RF signal amplification circuit is formed by sequentially connecting a second link control switch, an uplink low-noise amplifier, an uplink automatic gain control unit, an uplink power amplifier, and a first link control switch.

[0022] The first output terminal of the power distribution unit is connected to the first link control switch, and the second output terminal is connected to the input terminal of the power distribution unit of the next-level wireless signal coverage device.

[0023] The output of the radio frequency signal processing unit is connected to an antenna, which transmits downlink radio frequency signals to the terminal or receives uplink radio frequency signals transmitted by the terminal.

[0024] The control unit

[0025] The output power of the local wireless signal coverage device configured by the base station;

[0026] Monitor the output power values ​​of the uplink and downlink and adjust the gain of the uplink and downlink in real time according to the target power; output the gain control signal to the uplink automatic gain control unit or the downlink automatic gain control unit.

[0027] The wireless signal coverage device also includes:

[0028] The detection module is used to automatically detect the standing waves of the antenna system.

[0029] The detection module includes:

[0030] A bidirectional coupler is used to connect the output of the radio frequency signal processing unit to the antenna.

[0031] The two outputs of the bidirectional coupler are connected to the forward detector and the backward detector, respectively.

[0032] The forward and backward detectors are connected to the control unit, and the detected forward and backward voltages are input to the control unit.

[0033] The control unit monitors the voltage standing wave ratio in real time.

[0034] The beneficial technical effects achieved by this invention are as follows:

[0035] 1. The distributed antenna system in this invention can realize both base station radio frequency remote extension and active indoor distribution system:

[0036] 2. The power distribution units of wireless signal coverage devices at all levels extend the base station's radio frequency signal through radio frequency cables, solving the problem of base station signal coverage failure due to obstruction and expanding the base station's coverage area;

[0037] 3. The wireless signal coverage device in this invention has TDD function. It amplifies the uplink and downlink signals separately through the radio frequency signal processing unit, which can eliminate the path loss between the base station and the terminal, ensure that the base station and the terminal can receive the signal correctly, and effectively guarantee the communication quality of the uplink and downlink signals.

[0038] 4. In existing radio remote extension systems, the baseband processing unit (BBU) and the radio remote extension unit (RRU) communicate via the Common Public Radio Interface (CPRI), which requires a complex and costly signal processing component in the RRU. In this invention, the base station and the wireless signal coverage device distinguish uplink and downlink signal cycles through control signals, which reduces costs and is easy to implement.

[0039] 5. The uplink and downlink gains in this invention are adjustable. The uplink and downlink gains are automatically adjusted according to the magnitude of the control signal and the input RF signal, so that the uplink and downlink RF links can operate at the target power.

[0040] 6. The wireless signal coverage device of the present invention can automatically detect the standing wave of the antenna system.

[0041] For the foregoing and related purposes, one or more embodiments include features that will be described in detail below and particularly pointed out in the claims. The following description and accompanying drawings detail certain exemplary aspects and indicate only a few of the various ways in which the principles of the various embodiments can be utilized. Other benefits and novel features will become apparent upon consideration of the following detailed description in conjunction with the accompanying drawings, and the disclosed embodiments are intended to include all such aspects and their equivalents. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of a distributed antenna system application provided by an embodiment of the present invention;

[0043] Figure 2 This is a block diagram of a distributed antenna system provided in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the structure of the wireless signal coverage device provided in an embodiment of the present invention. Detailed Implementation

[0045] The following description and accompanying drawings fully illustrate specific embodiments of the invention to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, procedural, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Some portions and features of some embodiments may be included in or replace portions and features of other embodiments. The scope of embodiments of the invention includes the entire scope of the claims and all available equivalents thereof. In this document, these embodiments of the invention may be referred to individually or collectively with the term "invention," which is merely for convenience and is not intended to automatically limit the scope of the application to any single invention or inventive concept if more than one invention is disclosed.

[0046] Example 1

[0047] This embodiment provides a distributed antenna system, including:

[0048] A device 100 for achieving wireless signal coverage is disposed between a terminal and a base station, through which the terminal communicates with the base station;

[0049] Multiple indoor wireless signal coverage devices 100 extend the base station's radio frequency signal range via radio frequency cables, thereby expanding the coverage area of ​​a single base station; application diagram as shown. Figure 1 As shown, this solves the problem of base station signal coverage failure due to obstruction.

[0050] Specifically, the wireless signal coverage device 100, such as Figure 2 As shown, it includes:

[0051] The control unit 110 receives the control signal 10 sent by the base station and transmits commands and performs data interaction with the base station through the interface signal 20.

[0052] The control unit 110 receives the control signal 10 sent by the base station and sends the control signal 10 to the radio frequency signal processing unit 130;

[0053] The control signal 10 includes uplink and downlink timing information of the base station signal, which is used to instruct the radio frequency signal processing unit 130 to turn on the downlink radio frequency signal amplification circuit 131 or the uplink radio frequency signal amplification circuit 132.

[0054] Specifically, the control signal 10 is used to instruct the radio frequency signal processing unit 130 to: turn on the downlink radio frequency signal amplification circuit and turn off the uplink radio frequency signal amplification circuit during the downlink operation of the base station signal; and turn on the uplink radio frequency signal amplification circuit and turn off the downlink radio frequency signal amplification circuit during the uplink operation of the base station signal.

[0055] The control unit 110 and the base station communicate via an RS485 bus, transmitting control signal 10 and interface signal 20; specifically,

[0056] Interface signal 20 is used for communication between the base station and the control unit MCU in the wireless signal coverage device 100, including sending and receiving two signals:

[0057] The interface signal 20 includes: the base station sending a command to the control unit 110 of all levels of devices 100, the command being used to instruct all wireless signal coverage devices 100 to send their own device ID number to the base station, the control unit 110 of each device sending its own device ID number information, and the base station sending the target operating power value information of each device.

[0058] Specifically, when the distributed antenna system is first started, the base station sends a command to the control unit 110 of all wireless signal coverage devices 100 via the RS485 bus. The command is used to instruct all wireless signal coverage devices to send their own device ID number to the base station.

[0059] Each wireless signal coverage device 100 receives the command through its respective control unit 110 and sends its own device ID number to the base station through the control unit 110;

[0060] The base station receives the device ID number of each device, configures the output power of each device 100 according to the different device ID numbers, i.e. the target operating power value of the device, and sends the target operating power value of each device 100 to the control unit 110 of each device.

[0061] Optionally, the program updates for the control unit MCU within the wireless signal coverage area can also be performed by the base station via the RS485 bus.

[0062] The distributed antenna system in this invention extends the base station signal range via radio frequency cables: the base station is connected to the power distribution unit of the first-level wireless signal coverage device via radio frequency cables, the output of the power distribution unit is connected to the input of the power distribution unit of the next-level wireless signal coverage device via radio frequency cables, and each wireless signal coverage device is cascaded via radio frequency cables to transmit downlink radio frequency signals; the power distribution unit allows the base station to connect to multiple antennas, thus forming a distributed antenna system.

[0063] The power distribution unit (Spl) 120 is a downlink radio frequency signal receiving unit of the wireless signal coverage device 100. It receives the downlink radio frequency signal entering the device and performs distribution processing on the downlink radio frequency signal entering the device, splitting the downlink radio frequency signal entering the device into two paths. One path is input to the radio frequency signal processing unit of the device and the other path is transmitted to the next level wireless signal coverage device.

[0064] Specifically, such as Figure 2 As shown, the power distribution unit 120 in this embodiment is a power divider with two output terminals;

[0065] The power distribution unit 120 of the first-level wireless signal coverage device receives the downlink radio frequency signal 30 sent by the base station through the radio frequency cable. The first output of the power distribution unit 120 of the first-level device 100 is connected to the radio frequency signal processing unit 130 of this level, and the second output is connected to the power distribution unit 120 of the second-level device through the radio frequency cable.

[0066] The power distribution unit 120 of the second-level device receives the downlink radio frequency signal entering this level, that is, the downlink radio frequency signal output by the second output terminal of the first-level power distribution unit 120 through the radio frequency cable, and splits the downlink radio frequency signal into two paths. The first output terminal is connected to the radio frequency signal processing unit 130 of this level, and the second output terminal is connected to the power distribution unit 120 of the third-level device through the radio frequency cable.

[0067] In this way, the power distribution units 120 of the wireless signal coverage devices at all levels are cascaded through radio frequency cables to extend the radio frequency signal of the base station.

[0068] After the base station radio frequency signal is extended through the radio frequency cable, the signal power at the end of the cable is reduced due to cable loss. In current communication systems, the output power of the base station is very high, but the power of the terminal is generally less than 1W due to the influence of equipment size and power consumption. Therefore, due to the cable loss, the signal power entering the terminal is less than the terminal's receiving sensitivity, so the terminal cannot receive the correct signal, resulting in uplink communication interruption.

[0069] In view of this, the wireless signal coverage device 100 of the present invention further includes a radio frequency signal processing unit 130 that amplifies the uplink radio frequency signal or the downlink radio frequency signal respectively, and outputs the amplified radio frequency signal to the terminal to eliminate path loss between the base station and the terminal, ensuring that the base station and the terminal can receive the signal correctly, thereby ensuring reliable communication.

[0070] The radio frequency signal processing unit 130 amplifies the uplink radio frequency signal or the downlink radio frequency signal according to the control signal.

[0071] Specifically, such as Figure 3 As shown, the radio frequency signal processing unit 130 includes:

[0072] Downlink RF signal amplification circuit 131: includes a first link control switch SWT1, a downlink low noise amplifier LNA1, a downlink automatic gain control unit AGC1, a downlink power amplifier PA1, and a second link control switch SWT2;

[0073] Uplink RF signal amplification circuit 132 includes a second link control switch SWT2, an uplink low noise amplifier LNA2, an uplink automatic gain control unit AGC2, an uplink power amplifier PA2, and a first link control switch SWT1.

[0074] The specific circuit connection is as follows: One end of the first link control switch SWT1 is connected to the first output terminal of the power distribution unit Spl, receiving the local RF signal sent by Spl. The other end of SWT1 is connected to the input terminal of LNA1. The output terminal of LNA1 is connected to the input terminal of AGC1. The output terminal of AGC1 is connected to the input terminal of PA1. The output terminal of PA1 is connected to switch SWT2. The local downlink RF signal is amplified by LNA1, AGC1, and PA1. The amplified downlink RF signal is then transmitted to the terminal through the antenna connected to SWT2.

[0075] The second link control switch SWT2 is connected to the input of LNA2. SWT2 sends the uplink RF signal received by the antenna to LNA2, AGC2 and PA2 for amplification in sequence. The output of LNA2 is connected to the input of AGC2, the output of AGC2 is connected to the input of PA2, and the output of PA2 is connected to switch SWT1. The amplified uplink RF signal is sent to the base station through the RF cable connected to Spl.

[0076] According to the control signal 10, the first link control switch SWT1 and the second link control switch SWT2 select the downlink radio frequency signal processing unit 131 or the uplink radio frequency signal processing unit 132 to ensure normal communication between the base station and the terminal.

[0077] Specifically, the control unit 110 outputs the control signal 10 to the first link control switch SWT1, the second link control switch SWT2, the downlink low noise amplifier LNA1, the downlink power amplifier PA1, the uplink low noise amplifier LNA2, and the uplink power amplifier PA2;

[0078] After the SWT1 and SWT2 of each level of the device are extended in actual deployment, the normal communication between the base station and the terminal is ensured.

[0079] SWT1 and SWT2 turn on the downlink RF signal processing unit and turn off the uplink RF signal processing unit according to control signal 10: SWT1 connects to the input of LNA1 and disconnects PA2, SWT2 connects to the output of PA1 and disconnects LNA2, SWT1 transmits the RF signal sent by the first output of Spl to LNA1, and after being amplified by LNA1, AGC1 and PA1, it is sent to the terminal through the second antenna of the SWT2 link;

[0080] When the control signal is high, the power supply of LNA1 and PA1 is turned on; at the same time, the power supply of LNA2 and PA2 is turned off. When the control signal is low, the power supply of LNA2 and PA2 is turned on; at the same time, the power supply of LNA1 and PA1 is turned off. The low-noise amplifiers LNA1 and LNA2 amplify the uplink low-power RF signal or downlink low-power RF signal entering the RF signal processing unit to ensure the information quality of the base station RF signal after amplification.

[0081] Automatic gain control units AGC1 and AGC2 determine the amplification gain of the uplink and downlink radio frequency links based on the uplink and downlink radio frequency link gain control signal 30 output by control unit 110, so as to ensure that the base station radio frequency signal is not distorted.

[0082] Specifically, the control unit MCU is connected to the uplink automatic gain control unit AGC1 and the downlink automatic gain control unit AGC2. According to the target output power, it outputs uplink and downlink RF link gain control signals 30 to AGC1 or AGC2. The control unit MCU automatically adjusts the gain of the uplink and downlink RF links according to the signal magnitude input to the device based on the target output power, so as to ensure that the output RF signal is not distorted and to ensure the communication quality of the base station and the terminal.

[0083] During the operation of the distributed antenna system, the control unit MCU of each level of the wireless signal coverage device 100 monitors the output power of the uplink and downlink in real time, compares it with the target operating power value of the device configured by the base station, and adjusts the uplink and downlink gain in real time so that the device always operates at the target power value.

[0084] Power amplifiers PA1 and PA2 further amplify the uplink or downlink radio frequency signals to eliminate link losses between the base station and the terminal.

[0085] The wireless signal coverage device 100 receives the uplink radio frequency signal through the antenna, and turns on the uplink radio frequency signal amplification circuit and turns off the downlink radio frequency signal amplification circuit according to the control signal: SWT2 is connected to the input terminal of LNA2 and disconnected from PA1, SWT1 is connected to the output terminal of PA2 and disconnected from LAN1, and SWT2 transmits the radio frequency signal received by the antenna from the terminal to LNA2. After amplification by LNA2, AGC2 and PA2, it is sent to the base station through the radio frequency cable connected by the power distribution unit Spl.

[0086] Although there is still loss in the radio frequency cable after the base station radio frequency signal is extended through the radio frequency cable, the wireless signal coverage device in this invention has TDD function, which can amplify the uplink and downlink signals separately, eliminate the loss of the cable path between the base station and the terminal, and ensure that the base station and the terminal can receive the signal correctly, thereby ensuring reliable communication.

[0087] Furthermore, the wireless signal coverage device 100 of the present invention also includes a detection module 140, which is capable of automatically detecting the standing wave of the antenna system, such as... Figure 3 As shown,

[0088] The detection module 140 is disposed between the output terminal of the radio frequency signal processing unit 130 and the antenna, and the antenna is used to communicate with the terminal;

[0089] Furthermore, the detection module 140 includes:

[0090] Forward detector 142, backward detector 143,

[0091] A bidirectional coupler 141 is connected between the output of the RF signal processing unit and the antenna. The two outputs of the bidirectional coupler are connected to a forward detector 142 and a backward detector 143, respectively. The forward detector 142 outputs a forward power detection voltage (VFW), and the backward detector 143 outputs a reverse power detection voltage (VRE). The forward power detection voltage (VFW) and the backward power detection voltage (VRE) are input to the control unit 110, which judges the standing wave and performs corresponding operations.

[0092] When the system detects that the voltage standing wave ratio is higher than a certain value, the following actions are taken:

[0093] (1) When VSWR>3V and VFW-VRE<0.093V, reduce the transmission power by 3dB and send an alarm signal to the system;

[0094] (2) The control unit continues to monitor the voltage standing wave ratio (VSWR). If the VSWR returns to normal (VFW-VRE>0.16V and VSWR<3), the normal transmission power is restored. If the VSWR remains poor for a period of time (e.g., 5 minutes, 10 minutes), proceed according to steps 3 and 4 below.

[0095] (3) When 0V≤VFW-VRE<0.93V (6>VSWR>3), reduce the transmission power by 3dB;

[0096] (4) When VFW-VRE≤0V (VSWR≥6), reduce the transmit power by 10dB;

[0097] (5) Continue to monitor the voltage standing wave ratio. If the voltage standing wave ratio remains poor for a long period of time (e.g., 1-2 days), the device will upload a warning message to the base station, and the base station will send a warning message to the on-duty personnel through the network management system.

[0098] Those skilled in the art will also understand that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments herein can be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate the interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps described above are generally described in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art can implement the described functionality in alternative ways for each specific application; however, such implementation decisions should not be construed as departing from the scope of this disclosure.

[0099] The steps of the methods or algorithms described in conjunction with the embodiments herein can be directly embodied in hardware, software modules executed by a processor, or a combination thereof. The software modules can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. Alternatively, the processor and storage medium can exist as discrete components in the user terminal.

[0100] For software implementation, the techniques described in this application can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described in this application. This software code can be stored in memory units and executed by a processor. The memory units can be implemented within the processor or outside the processor; in the latter case, they are communicatively coupled to the processor via various means, as is well known in the art.

Claims

1. A distributed antenna system, characterized in that, include: A base station, and at least one wireless signal coverage device cascaded via a radio frequency cable; The base station is connected to the first-level wireless signal coverage device via an RF cable and transmits the base station's RF signal to the first-level wireless signal coverage device. The base station outputs control signals to various levels of wireless signal coverage devices, and the control signals are used to indicate the uplink and downlink operation periods of the base station signal; The wireless signal coverage devices at all levels open the uplink or downlink radio frequency link according to the control signal and amplify the radio frequency signal. The wireless signal coverage device includes: The power distribution unit splits the downlink radio frequency signal input to the local wireless signal coverage device into two paths: one path is input to the local radio frequency signal processing unit, and the other path is transmitted to the next level wireless signal coverage device. The control unit receives control signals sent by the base station and sends the control signals to the radio frequency signal processing unit; it also transmits commands and performs data interaction with the base station through interface signals. The radio frequency signal processing unit, according to the control signal, turns on the uplink radio frequency signal amplification circuit and turns off the downlink radio frequency signal amplification circuit, or turns on the downlink radio frequency signal amplification circuit and turns off the uplink radio frequency signal amplification circuit; and amplifies the uplink radio frequency signal or the downlink radio frequency signal. The radio frequency signal processing unit includes: A downlink radio frequency signal amplification circuit consisting of a first link control switch, a downlink low-noise amplifier, a downlink automatic gain control unit, a downlink power amplifier, and a second link control switch connected in sequence; An uplink RF signal amplification circuit is formed by sequentially connecting a second link control switch, an uplink low-noise amplifier, an uplink automatic gain control unit, an uplink power amplifier, and a first link control switch. The control unit receives the output power of the local wireless signal coverage device configured by the base station; monitors the output power values ​​of the uplink and downlink, and adjusts the gain of the uplink and downlink in real time according to the target power; and outputs a gain control signal to the uplink automatic gain control unit or the downlink automatic gain control unit. When the control signal is high, the power supply of the downlink low-noise amplifier and the downlink power amplifier is turned on; at the same time, the power supply of the uplink low-noise amplifier and the uplink power amplifier is turned off. When the control signal is low, the power supply of the uplink low-noise amplifier and the uplink power amplifier is turned on; at the same time, the power supply of the downlink low-noise amplifier and the downlink power amplifier is turned off. The uplink low-noise amplifier and the downlink low-noise amplifier amplify the uplink low-power RF signal or the downlink low-power RF signal entering the RF signal processing unit. The control unit is connected to the uplink automatic gain control unit and the downlink automatic gain control unit. According to the target output power, it outputs uplink and downlink RF link gain control signals to the uplink automatic gain control unit or the downlink automatic gain control unit. The control unit automatically adjusts the gain of the uplink and downlink RF links according to the signal magnitude input to the device based on the target output power. The control units of wireless signal coverage devices at all levels monitor the output power of uplink and downlink in real time, compare it with the target operating power value of the device configured by the base station, and adjust the uplink and downlink gain in real time. The wireless signal coverage device further includes: a detection module for automatically detecting the standing wave ratio (SWR) of the antenna system; the detection module includes: a bidirectional coupler connected between the output of the radio frequency signal processing unit and the antenna; the two outputs of the bidirectional coupler are respectively connected to a forward detector and a backward detector; the outputs of the forward detector and the backward detector are connected to a control unit, and the detected forward voltage and backward voltage are input to the control unit; the control unit judges the SWR and performs corresponding operations; when the detected SWR is higher than a predetermined value, the following processing is performed: (1) When VSWR>3V and VFW-VRE<0.093V, reduce the transmit power by 3dB and send an alarm signal to the system; (2) The control unit continues to monitor the voltage standing wave ratio (VSWR), and restores normal transmission power when VFW-VRE>0.16V and VSWR<3; (3) When 0V≤VFW-VRE<0.93V (6>VSWR>3), reduce the transmit power by 3dB; (4) When VFW-VRE≤0V (VSWR≥6), reduce the transmit power by 10dB; (5) Continue to monitor the voltage standing wave ratio. If the voltage standing wave ratio is abnormal for a long time, the device will upload a warning message to the base station, and the base station will send a warning message to the duty personnel through the network management system.

2. The distributed antenna system as described in claim 1, characterized in that, include: The base station inputs control signals to the control units of wireless signal coverage devices at all levels; The first output of the power distribution unit is connected to the radio frequency signal processing unit of the same level, and the second output is connected to the input of the power distribution unit of the next level wireless signal coverage device through a radio frequency cable. The wireless signal coverage devices at each level are cascaded through radio frequency cables to extend the radio frequency signal of the base station.

3. The distributed antenna system as described in claim 1, characterized in that, The first output terminal of the power distribution unit is connected to the first link control switch, and the second output terminal is connected to the input terminal of the power distribution unit of the next-level wireless signal coverage device. The output of the radio frequency signal processing unit is connected to an antenna, which transmits downlink radio frequency signals to the terminal or receives uplink radio frequency signals transmitted by the terminal.

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