TWI641242B - Decentralized antenna system capable of automatically compensating signal strength - Google Patents

Abstract

The present invention is a decentralized antenna system capable of automatically compensating for signal strength, comprising a head end unit for outputting a first control command; and at least one remote antenna unit, the remote antenna unit receiving the first control command The actual downlink signal strength is measured, and the line compensation information is generated according to the actual downlink signal strength and the preset downlink signal strength information in the first control command. When the remote antenna unit receives the next optical signal, it converts the optical signal back to the downlink RF signal, and compensates the signal strength of the downlink RF signal according to the downlink compensation information. When the remote antenna unit transmits the downlink RF signal, the signal strength of the transmitted RF signal can be the same as the preset signal strength to provide sufficient coverage and stable communication quality.

Description

Decentralized antenna system capable of automatically compensating signal strength

The invention relates to a decentralized antenna system, in particular to a decentralized antenna system capable of automatically compensating for signal strength.

With the advancement of wireless communication technology, wireless Internet access of mobile devices has become the main development trend of mobile devices. The mobile device accesses the Internet through radio frequency (RF) signals to communicate with the base station set by the telecommunications operator to provide the wireless Internet access function of the mobile device. Generally, the RF signal is affected by the terrain and the building during the transmission process. For example, when the mobile device is in the enclosed space of the building, such as an elevator or a basement, the RF signal sent by the base station will be transmitted by the building. Floor and wall barriers prevent the mobile device from communicating with the base station, making the mobile device unable to communicate or access the Internet.

Please refer to the conventional decentralized antenna system 40 shown in FIG. 5, which has a head end unit (HEU) 41 and a plurality of remote antenna units (RAU) 42. The head end unit 41 is provided at The location where the RF signal sent by the base station 50 is clearly received, such as the roof of a building, connected to the base station 50 through a wireless connection, or installed in a computer room and connected to the base station 50 through a wired connection to receive After the RF signal sent by the base station 50 is converted into a transmission signal, the transmission signal is transmitted by a wired method. The remote antenna units 42 are connected to the head-end unit 41 in a wired manner, so as to receive the transmission signals transmitted by the head-end unit 41, and the remote antenna units 42 convert the received transmission signals back to the After the RF signal, the RF signal is transmitted through an antenna unit, so that the remote antenna units 42 can be set in the building The RF signal sent by the base station is not received or the location where the RF signal is poor, such as an elevator or a basement, is used to provide the mobile device 60 located in the elevator or the basement to talk or access the Internet.

For example, when the remote antenna units 42 are installed in the basement, the remote antenna units 42 are evenly distributed in appropriate positions in the basement because the area of the basement is relatively large, so that all positions in the basement can be received. RF signals sent by the remote antenna units 42. In this way, when the mobile device 60 is in the basement and cannot directly communicate with the base station 50, the mobile device 60 receives the RF signals sent by the remote antenna units 42 and passes the remote antenna units 42 and The head-end unit 41 is connected to the base station 50 so that the mobile device 60 can maintain a call or access the Internet.

However, in the process of transmitting the transmission signal to the remote antenna units 42 by the head-end unit 41, since the signal strength of the transmission signal will decrease with the transmission distance, the signals received by the remote antenna units 42 Is the attenuated transmission signal. In addition, since the transmission distance of the RF signals sent by the remote antenna units 42 is directly proportional to the signal strength of the transmission signals received by the remote antenna units 42, the remote antenna units 42 convert the transmission signals back to When the RF signal is sent for reception by the mobile device 60, the transmission distance of the RF signal sent by the remote antenna units 42 will be reduced due to the attenuation of the transmission signal during the transmission process, which in turn makes the remote antenna units 42 The coverage of the transmitted RF signal is reduced, resulting in that the mobile device 60 outside the coverage cannot communicate or access the Internet, or the quality of the communication and access is poor. Therefore, the prior art decentralized antenna system 40 is bound to be further improved.

In view of the fact that the distributed antenna system of the prior art transmits the transmission signal, the transmission signal strength will decrease with the transmission distance, resulting in a reduction in the transmission distance of the RF signal sent by the remote antenna unit, so that the mobile device's wireless network calls Or the disadvantage of degraded Internet access, the present invention provides A distributed antenna system capable of automatically compensating for signal strength to compensate for the signal strength. The distributed antenna system capable of automatically compensating for signal strength includes: a head-end unit for outputting a first control command, and the head-end unit for receiving A downlink radio frequency (RF) signal and converting the downlink RF signal into a lower line optical signal, and outputting the downlink optical signal; wherein the first control command includes a preset downlink signal strength information; at least one remote end An antenna unit connected to the head-end unit to receive the first control command and the downlink optical signal; wherein when the at least one remote antenna unit receives the first control command, the at least one remote antenna unit measures An actual downlink signal strength of the output signal of the head-end unit, and the following line compensation information is generated according to the actual downlink signal strength and the preset downlink signal strength information in the first control command; wherein when the at least one remote antenna unit When the downlink optical signal is received, the at least one remote antenna unit converts the downlink optical signal back to the downlink RF signal, According to the compensation information to compensate for the downlink downlink signal strength of the RF signals, and the at least one remote antenna unit via an antenna transmitting the downlink RF signal.

The distributed antenna system capable of automatically compensating for the signal strength of the present invention sends a first control command with the preset downlink signal strength information through the head-end unit for the remote antenna unit to receive. When the remote antenna unit receives the first control command, it can calculate the first control command according to the actual downlink signal strength of the output signal of the head-end unit and the preset downlink signal strength information in the first control command. The amount of attenuation during transmission, and the downlink compensation information is generated accordingly. When the remote antenna unit receives the downlink optical signal, since the remote antenna unit already knows the attenuation degree of the signal during transmission according to the first control command, the remote antenna unit can then The compensation information compensates the converted downlink RF signal so that the compensated downlink RF signal has the same strength as the preset signal. Since the remote antenna unit sends the downlink RF signal after compensation, the signal strength of the compensated downlink RF signal sent by the remote antenna unit can be compared with the head end. The signal strength (default strength) of the downlink RF signal of the unit is the same to provide sufficient coverage and allow the mobile device to have stable communication quality.

10‧‧‧Multi-band Distributed Antenna System

11‧‧‧ head-end unit

111‧‧‧Port

112‧‧‧Duplexer

113‧‧‧ downlink transmission unit

1131‧‧‧ Downlink RF Gainer

1132‧‧‧ Downward Electro-optical Converter

1133‧‧‧ Downlink Optical Signal Splitter

114‧‧‧ uplink receiving unit

1141‧‧‧Uplink RF Gainer

1142‧‧‧uplink RF signal combiner

1143‧‧‧Uplink photoelectric converter

115‧‧‧ fiber optic port

12‧‧‧Remote antenna unit

121‧‧‧ fiber port

122‧‧‧ downlink receiving unit

1221‧‧‧ Downlink Optical Signal Splitter

1222‧‧‧ Downlink Photoelectric Converter

1223‧‧‧ Downlink RF Digital Step Attenuator

123‧‧‧ uplink transmission unit

1231‧‧‧Uplink Optical Signal Combiner

1232‧‧‧ Uplink electro-optical converter

1233‧‧‧ Uplink RF Digital Step Attenuator

124‧‧‧RF Gainer

125‧‧‧ Antenna

20‧‧‧Base Station

30‧‧‧ mobile device

40‧‧‧ decentralized antenna system

41‧‧‧ head-end unit

42‧‧‧Remote antenna unit

50‧‧‧ base station

60‧‧‧ mobile device

FIG. 1 is a system block diagram of a distributed antenna system capable of automatically compensating for signal strength according to the present invention.

FIG. 2 and FIG. 3 are schematic flowcharts of a distributed antenna system capable of automatically compensating for signal strength according to the present invention.

FIG. 4 is a schematic circuit diagram of a distributed antenna system capable of automatically compensating for signal strength according to the present invention.

FIG. 5 is a system block diagram of a conventional distributed antenna system.

In the following, the technical means adopted by the present invention to achieve the intended purpose will be further explained in conjunction with the drawings and the preferred embodiments of the present invention.

Please refer to FIG. 1. The present invention is a distributed antenna system 10 (Distributed Antenna Systems; DAS) capable of automatically compensating for signal strength, including a head end unit (HEU) 11 and at least one remote antenna unit. 12 (Remote Antenna Unit; RAU).

The head-end unit 11 outputs a first control command, and the first control command includes a preset downlink signal strength information, wherein the preset downlink signal strength information corresponds to the output signal of the head-end unit 11. For example, when the output power of the output signal of the head-end unit 11 is higher, the preset downlink signal strength information reflects a larger value. Generally speaking, the output power of the output signal of each head-end unit 11 is related to its own component characteristics, so the output power of the output signal of each head-end unit 11 does not change after leaving the factory, but the output signal of each head-end unit 11 The output power is not necessarily the same. Therefore, each head end unit 11 will be measured before leaving the factory. The output power of the output signal is generated, and the preset downlink signal strength information is generated and stored in each head-end unit 11.

In addition, the head-end unit 11 is for connecting to a base station 20 to receive a lower radio frequency (RF) signal transmitted by the base station 20 and convert the downlink RF signal into a lower optical signal. Output the downlink optical signal. Therefore, the head-end unit 11 can output the first control command and the downlink optical signal to the outside. The head-end unit 11 may be connected to the base station 20 in a wired manner through a coaxial cable, or wirelessly connected to the base station 20 through an antenna to receive the RF signal sent by the base station 20. In this preferred embodiment, the connection between the head-end unit 11 and the base station 20 is described by taking a wired connection as an example.

The remote antenna unit 12 is connected to the head-end unit 11 to receive the first control command and the downlink optical signal, respectively. When the remote antenna unit 12 receives the first control command, the remote antenna unit 12 measures an actual downlink signal strength of the output signal of the head-end unit 11, and according to the actual downlink signal strength and the first The default downlink signal strength information in the control command generates the following line compensation information. When the remote antenna unit 12 receives the downlink optical signal, the remote antenna unit 12 converts the downlink optical signal back into the downlink RF signal, and compensates the signal strength of the downlink RF signal according to the downlink compensation information. In addition, the remote antenna unit 12 has an antenna for transmitting the downlink RF signal through the antenna. In this preferred embodiment, the head-end unit 11 is connected to the remote antenna unit 12 through an optical fiber cable. In this preferred example, the output signal of the head-end unit 11 may be the first control command or the downlink optical signal.

The decentralized antenna system 10 capable of automatically compensating for the signal strength sends a first control command with the preset downlink signal strength information through the head-end unit 11 for the remote antenna unit 12 to receive. Because the first control command has the preset downlink signal strength information, and the preset downlink signal strength information indicates the signal strength when the output signal of the head-end unit 11 is transmitted, when the remote antenna unit 12 receives When the first control command is executed, the actual output signal of the head-end unit 11 can be measured. The strength of the downlink signal, and determine the attenuation amount of the output signal of the headend unit 11 during transmission according to the actual signal strength of the first control command and the preset downlink signal strength information in the first control command, and based on the attenuation The decrement generates the downward compensation information. Thereafter, when the remote antenna unit 12 receives the downlink optical signal, since the remote antenna unit 12 has determined the attenuation degree of the output signal of the head-end unit 11 during transmission, that is, the downlink compensation information, Therefore, the remote antenna unit 12 can compensate the converted downlink RF signal according to the downlink compensation information, so that the remote antenna unit 12 sends the compensated downlink RF signal, so that the remote antenna unit 12 The signal strength of the compensated downlink RF signal sent can be the same as the signal strength of the downlink RF signal of the head-end unit 11 to provide sufficient coverage and allow the mobile device to have stable communication quality.

Please refer to FIG. 2. For example, when the head-end unit 11 is turned on, the head-end unit 11 first outputs the first control command (S201). When the remote antenna unit 12 receives the first control command, the remote antenna unit 12 measures the actual downlink signal strength of the output signal of the head-end unit (S202), and the remote antenna unit 12 is based on the The actual downlink signal strength (RAU PD Rx power) and the preset downlink signal strength information (HEU LD Tx power) in the first control command generate the downlink compensation information (S203).

In addition, after the remote antenna unit 12 generates the downlink compensation information (S203), the remote antenna unit 12 further outputs a completed reception signal to the head-end unit 11 (S204). When the head-end unit 11 receives the complete reception signal, the head-end unit 11 measures the actual uplink signal strength of the output signal of the remote antenna unit 12 to generate a second control command (S205) And the head-end unit 11 outputs the second control command to the remote antenna unit 12 (S206), wherein the second control command includes the actual line signal strength. Generally speaking, the output power of the output signal of each remote antenna unit 12 is related to its own component characteristics, so the output power of the output signal of each remote antenna unit 12 does not change after leaving the factory, but each remote antenna The output power of the output signal of the unit 12 is not necessarily the same. Therefore, each remote antenna unit 12 will measure its own output signal before leaving the factory. The output power of the signal is generated, and a preset uplink signal strength information is generated and stored in each remote antenna unit 12. Therefore, when the remote antenna unit 12 receives the second control command, the remote antenna unit 12 can receive the actual line signal strength (HEU PD Rx power) of the received signal and the preset Set the uplink signal strength information (RAU LD Tx power) to generate an uplink compensation information (S207). Then, after the remote antenna unit 12 generates the uplink compensation information, the remote antenna unit 12 further outputs a completion compensation signal to the head-end unit 11 (S208). Finally, the head-end unit 11 receives the completion compensation signal (S209). In this preferred example, the output signal of the remote antenna unit 12 may be the second control command or an uplink optical signal.

Please refer to FIG. 1 and FIG. 3 again. For example, when the head-end unit 11 receives the downlink RF signal from the base station 20 (S301), the head-end unit 11 converts the downlink RF signal into the A downlink optical signal, and output the downlink optical signal to the remote antenna unit 12 (S302). When the remote antenna unit 12 receives the downlink optical signal, the remote antenna unit 12 converts the downlink optical signal back to the downlink RF signal (S303), and the remote antenna unit 12 compensates according to the downlink compensation information. After the downlink RF signal, the downlink RF signal is sent through the antenna (S304) to the mobile device 30.

In addition, when the remote antenna unit 12 receives the uplink RF signal sent by the mobile device 30 (S305), the remote antenna unit 12 first compensates the uplink RF signal according to the uplink compensation information (S306), and after compensation, After the uplink RF signal is converted into the uplink optical signal, the uplink optical signal is output to the head-end unit 11 (S307). When the head-end unit 11 receives the uplink optical signal, the head-end unit 11 converts the uplink optical signal back to the uplink RF signal (S308), and outputs the uplink RF signal to the base station 20 (S309).

In this way, the distributed antenna system 10 of the present invention that can automatically compensate for signal strength can generate the downlink compensation information and the uplink compensation information. When the RF signal from the base station is received by the head-end unit 11, the head-end unit 11 converts the RF signal into an optical signal and transmits it to the remote antenna unit 12, and the remote antenna unit 12 converts the optical signal When sending back the RF signal, that is, the The antenna unit 12 can compensate the RF signal according to the downlink compensation information, so that the mobile device 30 can stably receive the data provided by the base station 20, so as to provide sufficient coverage and allow the mobile device 30 to have stable communication quality.

In addition, when the RF signal sent by the mobile device is received by the remote antenna unit 12, the remote antenna unit 12 converts the RF signal into an optical signal and returns it to the head-end unit 11, that is, when the uplink, the remote The end antenna unit 12 can first compensate the uplink RF signal according to the uplink compensation information, so that the uplink RF signal is converted into an optical signal and transmitted to the head end unit 11. The signal strength of the optical signal can be the same as the preset, so that The end unit 11 converts the optical signal back to the RF signal and uploads it to the base station 20, so that the base station 20 can receive the data uploaded by the stable mobile device 30 to provide sufficient coverage and allow the mobile device 30 to communicate stably quality.

Further, as shown in FIG. 4, the head-end unit 11 includes a plurality of connection ports 111, a plurality of duplexers 112 (Duplexer), a lower transmission unit 113, an uplink receiving unit 114, and a plurality of optical fiber connection ports 115. .

The ports 111 are for connecting to the base station 20 to receive the RF signal sent by the base station 20, and the ports 111 are connected to the downlink transmitting unit 113 and the uplink receiving through a duplexer 112, respectively. Unit 114.

The downlink transmission unit 113 includes a downlink RF gain 1113, a down-row electrical-optical converter 1132, and a down-row optical signal splitter 1133. The downlink RF gain 1131 is connected to the duplexers 112, and the downlink RF gain 1131 is connected to the downlink optical signal distributor 1133 through the downlink electrical-optical converter 1132. The downlink optical signal distributor 1133 is connected to the optical fiber ports 115.

The uplink receiving unit 114 includes an uplink RF gain unit 1141, an uplink RF signal combiner 1142, and an uplink photoelectric converter 1143. The uplink RF gain amplifier 1141 is connected to these The duplexer 112 is connected to the optical fiber ports 115 through the uplink RF signal combiner 1142 and the uplink photoelectric converter 1143.

The remote antenna unit 12 includes an optical fiber port 121, a lower receiving unit 122, an uplink transmitting unit 123, a complex RF gain unit 124, and a complex antenna 125.

The optical fiber port 121 of the remote antenna unit 12 is connected to one of the optical fiber ports 115 of the head-end unit 11 through an optical fiber cable, and the optical fiber port 121 of the remote antenna unit 12 is connected to the downstream receiving unit 122. And the uplink transmission unit 123.

The downlink receiving unit 122 includes a downlink optical signal splitter 1221, a down-link photoelectric converter 1222, and a complex downlink RF digital step attenuator (DSA) 1223. The downstream optical signal distributor 1221 is connected to the optical fiber port 121 of the remote antenna unit 12, and the downstream optical signal distributor 1221 is connected to the downstream optical digital converter 1222 and one of the downstream RF digital step attenuators 1223. RFgainer 124. Each of the RF gain amplifiers 124 is connected to one of the antennas 125.

The uplink transmission unit 123 includes an uplink optical signal combiner 1231, an uplink electro-optical converter 1232, and a plurality of uplink RF digital step attenuators 1233. The uplink optical signal combiner 1231 is connected to the optical fiber port 121 of the remote antenna unit 12, and the uplink optical signal combiner 1231 is connected to the RF through the uplink electric-optical converter 1232 and one of the uplink RF digital step attenuators 1233. Gainer 124.

In the preferred embodiment, the remote antenna unit 12 further has a microcontroller unit (MCU) (not shown), and the microcontroller unit measures the actual signal strength of the first control command, and Generating the downlink compensation information according to the actual downlink signal strength and preset downlink signal strength information in the first control command, and the microcontroller unit further adjusts the downlink RF digital step attenuator 1223 according to the downlink compensation information, To compensate the downlink RF signal. In addition, the microcontroller unit is further based on the actual signal strength in the second control command and the preset of the remote antenna unit 12. The uplink signal strength information generates the uplink compensation information, and the microcontroller unit further adjusts the uplink RF digital step attenuator 1233 according to the uplink compensation information to compensate the uplink RF signal.

In this way, the head-end unit 11 can be connected to the base station 20 through the connection port 111 to receive the downlink RF signal, and the duplexer 112, the downlink transmission unit 113, and the optical fiber connection ports 115 will The RF signal sent by the base station 20 is converted into the downlink optical signal and output to the remote antenna unit 12. The remote antenna unit 12 can be connected to the head-end unit 11 through the optical fiber port 121 of the remote antenna unit 12 to receive the downlink optical signal, and through the downlink receiving unit 122, the RF gain unit 124, and the The antenna 125 converts the optical signal transmitted by the head-end unit 11 back to an RF signal and sends it out for the mobile device 30 to receive.

In addition, the remote antenna unit 12 can receive the uplink RF signal sent by the mobile device 30 through the antenna 125, and through the RF gain units 124, the uplink transmission units 123, and the optical fiber ports of the remote antenna unit 12 121 converts the uplink RF signal sent by the mobile device 30 into the uplink optical signal and outputs it to the head-end unit 11. The head-end unit 11 can be connected to the remote antenna unit 12 through the optical fiber port 115 of the head-end unit 11 to receive the uplink optical signal, and through the uplink receiving unit 114, the duplexers 112, and the The port 111 converts the uplink optical signal transmitted by the remote antenna unit 12 back to the uplink RF signal and outputs it to the base station 20.

In the preferred embodiment, the downstream electro-optical converter 1132 and the upstream electro-optical converter 1232 are at least one laser diode, and the upstream photoelectric converter 1143 and the downstream photoelectric converter 1222 are respectively At least one photodiode.

The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Although the present invention has been disclosed as above with the preferred embodiments, they are not intended to limit the present invention, and any technology familiar with the profession Personnel, without departing from the scope of the technical solution of the present invention, can use the disclosed technical content to make some changes or modifications to equivalent embodiments of equivalent changes. Without departing from the content of the technical solution of the present invention, any simple modifications, equivalent changes, and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims (7)

A decentralized antenna system capable of automatically compensating for signal strength includes a head-end unit that outputs a first control command, and the head-end unit receives a lower radio frequency (RF) signal and transmits the downlink RF After the signal is converted into the following optical signal, the downlink optical signal is output; wherein the first control command has a preset downlink signal strength information; at least one remote antenna unit is connected to the head-end unit to receive the first control Command and the downlink optical signal; wherein when the at least one remote antenna unit receives the first control command, the at least one remote antenna unit measures an actual downlink signal strength of the output signal of the head-end unit, and The actual downlink signal strength and the preset downlink signal strength information in the first control command generate the following line compensation information; wherein when the at least one remote antenna unit receives the downlink optical signal, the at least one remote antenna unit will The downlink optical signal is converted back to the downlink RF signal, and the signal strength of the downlink RF signal is compensated according to the downlink compensation information, and the at least A remote antenna unit sends the downlink RF signal through an antenna; wherein when the at least one remote antenna unit generates the downlink compensation information, the at least one remote antenna unit further outputs a completed reception signal to the head-end unit; when When the head-end unit receives the complete reception signal, the head-end unit measures the actual signal strength of the output signal of the remote antenna unit to generate a second control command, and the head-end unit outputs the second control. Command to the at least one remote antenna unit; wherein the second control command includes the actual signal strength; when the at least one remote antenna unit receives the second control command, the at least one remote antenna unit The actual line signal strength of the completed received signal in the two control commands and a preset uplink signal strength information of the remote antenna unit generate an uplink compensation information. The decentralized antenna system capable of automatically compensating for signal strength according to claim 1, wherein the output signal of the head-end unit is the first control command or the downlink optical signal. The distributed antenna system capable of automatically compensating for signal strength according to claim 1, wherein the output signal of the remote antenna unit is the second control command or an uplink optical signal; when the at least one remote antenna unit receives a When the uplink RF signal is received, the at least one remote antenna unit compensates the uplink RF signal according to the uplink compensation information, and converts the compensated uplink RF signal into the uplink optical signal, and outputs the uplink optical signal to the headend unit. ; When the head-end unit receives the uplink optical signal, the head-end unit converts the uplink optical signal back to the uplink RF signal and outputs the uplink RF signal. The decentralized antenna system capable of automatically compensating for signal strength according to any one of claims 1 to 3, wherein the head-end unit includes: a plurality of ports for connecting to a base station to receive the base station RF signals sent; multiple duplexers, each connected to one of the ports; the lower transmission unit includes: the lower electrical-optical converter; the lower optical signal splitter; and the lower RF gain device connected to the Duplexers, and the downlink RF gain device is connected to the downlink optical signal splitter through the downlink electro-optical converter; an uplink receiving unit includes: an uplink RF signal combiner; an uplink photoelectric converter; and an uplink An RF gain device is connected to the duplexers, and the uplink RF gain device is connected to the uplink photoelectric converter through the uplink RF signal combiner; and a plurality of optical fiber ports are respectively connected to the downlink light of the downlink transmission unit. The signal distributor is respectively connected to the uplink photoelectric converter of the uplink receiving unit. The decentralized antenna system capable of automatically compensating for signal strength according to claim 4, wherein the at least one remote antenna unit includes: an optical fiber port, which is connected to one of the optical fibers of the head-end unit through an optical fiber cable Port; the lower receiving unit includes: a lower photoelectric converter; a complex downstream RF digital step attenuator (DSA) connected to the downstream photoelectric converter; and a lower optical signal distributor, Connected to the optical fiber port of the at least one remote antenna unit, and the downstream optical signal distributor is connected to one of the downstream RF digital step attenuators through the downstream photoelectric converter; an upstream transmission unit includes: an upstream electrical optical Converter; a complex uplink RF digital step attenuator connected to the uplink electro-optical converter; an uplink optical signal combiner connected to the optical fiber port of the at least one remote antenna unit, and the uplink optical signal combiner passed The uplink electro-optical converter is connected to one of the uplink RF digital step attenuators; the complex RF gain amplifier is connected to the downlink receiving unit respectively. Wherein a downstream RF digital step attenuator stage, and connected to the uplink transmission unit wherein a RF uplink digital step attenuator stage; and a plurality of antennas respectively connected to the RF gain of one. The decentralized antenna system capable of automatically compensating for signal strength according to claim 4, wherein: the downlink electro-optical converter of the downlink transmission unit of the head-end unit is at least one laser diode; and the uplink reception of the head-end unit The upstream photoelectric converter of the unit is at least one photoelectric diode. The decentralized antenna system capable of automatically compensating for signal strength according to claim 5, wherein: the downstream photoelectric converter of the downstream receiving unit of the at least one remote antenna unit is at least one photoelectric diode; the at least one remote end The uplink electro-optical converter of the uplink transmission unit of the antenna unit is at least one laser diode.