JP2024045924A - Base unit and wireless communication system - Google Patents

Abstract

[Problem] To provide a master unit and a wireless communication system that can reduce the circuit scale without degrading the signal quality of downstream signals in a distributed antenna system. [Solution] The master unit and the wireless communication system have analog circuits 21a-21d that perform analog processing of downstream signals from the base stations of each operator, analog combiners 22a, 22b that combine and combine downstream signals of operators that do not have adjacent frequency bands, A/D converters 24a, 24b that convert the output from the analog combiners 22a, 22b into a digital signal, a plurality of digital signal processing units 24a-24d that separate the digital signals into downstream signals for each operator, and a transceiver circuit 25 that transmits the separated downstream signals as optical signals, and combine the downstream signals of multiple operators without being affected by the signals of other operators. [Selected Figure] Figure 3

Description

The present invention relates to a base unit and a wireless communication system of a distributed antenna system, and particularly to a base unit and a wireless communication system that can reduce the circuit scale without degrading the signal quality of downlink signals output from slave units. Regarding.

Description of the Prior Art
In closed spaces such as inside buildings and tunnels, multi-carrier DAS (Distributed Antenna Systems) are becoming more common. Multi-carrier DAS (infrastructure sharing-compatible DAS) transmits and receives radio waves from multiple carriers.

[Example of infrastructure sharing compatible DAS configuration: Figure 5]
A configuration example of an infrastructure sharing compatible DAS will be described with reference to Fig. 5. Fig. 5 is an explanatory diagram showing a configuration example of an infrastructure sharing compatible DAS.
The infrastructure sharing-compatible DAS includes a parent unit (parent unit #1 in the figure) 110 that transmits and receives data with base stations 100 of multiple operators, a number of aggregation devices 120 (aggregation #1 to aggregation #M in the figure) connected to the parent unit 110 by optical cables, and a number of child units 130 (child units #1 to #M*N in the figure) connected to each aggregation device 120 by optical cables.
In the example of FIG. 5, a base station 100a of an operator A and a base station 100d of an operator D are shown as the base stations 100 of the operators.

The parent device 110 receives radio signals (downstream signals/DL) from multiple base stations 100, converts them into optical signals and outputs them to the aggregation device 120, and converts the optical signals (upstream signals/UL) from the aggregation device 120 into radio signals and outputs them to the corresponding base stations 100.
The master unit 110 and each base station 100 are connected by a coaxial cable, and perform analog communication for uplink and downlink signals. The number of coaxial cable interfaces is set according to the supported frequency arrangement (number of bands of wireless signals) and the number of MIMOs (Multiple-Input and Multiple-Output) of each operator.

The aggregation device 120 connects the parent device 110 and multiple child devices 130 via an optical cable to perform data communication. It receives optical signals from the parent device 110 and distributes them to the multiple child devices 130, and also receives optical signals from the multiple child devices 130 and outputs them to the parent device 110.

The slave unit 130 is connected to the aggregation device 120 via an optical cable, converts an optical signal from the aggregation device 120 into a wireless signal, and outputs the wireless signal from an antenna. The slave unit 130 also converts a wireless signal received by the antenna into an optical signal, and outputs the optical signal to the aggregation device 120.
The slave devices 130 are wireless communication devices equipped with directional antennas, for example, installed in various locations (ceilings, walls, floors, etc.) in a building, and perform wireless communication with wireless terminal devices 140 of multiple carriers. Fig. 5 shows a configuration in which N slave devices 130 are connected to M aggregation devices 120, respectively.

In FIG. 5, as the wireless terminal devices 140, a wireless terminal device 140a of a business operator A and a wireless terminal device 140d of a business operator D are shown. By using a DAS shared by carriers, wireless terminal devices 140 of multiple carriers located in a building or the like can transmit and receive information via the shared handset 130.

[Example of operation of infrastructure sharing compatible DAS]
For example, a DAS supporting infrastructure sharing for 4 carriers and 32 slave units includes the base stations 100 of the 4 carriers, one base unit 110, 4 aggregators 120, and 32 slave units 130. There is a configuration in which eight slave devices 130 are connected to each aggregation device 120.

Furthermore, when constructing an infrastructure sharing compatible DAS in a building, there are cases in which one to several handsets 130 are placed on each floor, and one system is assigned to multiple floors of multiple buildings.
In infrastructure sharing, it is necessary to control the operation of each operator on a building-by-building or floor-by-floor basis, and each slave unit 130 controls the operation (ON)/stopping (OFF) of each operator.

[Example of operation ON/OFF for each business operator: Figure 6]
An example of operation ON/OFF for each provider in infrastructure sharing compatible DAS will be explained using FIG. 6. FIG. 6 is an explanatory diagram showing an example of operation ON/OFF for each company.
FIG. 6 shows the downlink signal in the infrastructure sharing compatible DAS equipped with the above-mentioned 32 handsets 130 (handles #1 to #32), when each handset is set to operate on a per-operator basis. Showing the output.

Of the 32 slave units 130, slave units #1 to #6 are set to be operational for all operators A, B, C, and D; ~As for the downlink signal from handset #6, the frequencies of all carriers are output as shown in FIG. 6(a).

For child devices #7 to #18, operation is set to ON for operators A, B, and D, and operation is set to OFF for operator C. As shown in FIG. 6(b), these child devices output frequencies corresponding to operators A, B, and D, but output of the frequency corresponding to operator C is stopped.

For handset #19 to #24, operation is set to ON for carriers A and C, and OFF is set for carriers B and D, as shown in FIG. 6(c). As such, frequencies corresponding to carriers A and C are output, and frequencies corresponding to carriers B and D are not output.

For handset #25 to #32, operation is set to ON for carriers B and C, and OFF is set for carriers A and D, as shown in FIG. 6(d). , carrier B, and carrier C are output.
In this way, the operator's operations are controlled on a building-by-building or floor-by-floor basis.

[Configuration of a conventional wireless communication system: Fig. 7]
Next, the configuration of a conventional wireless communication system will be described with reference to Fig. 7. Fig. 7 is an explanatory diagram showing the configuration of a conventional wireless communication system.
7 shows the configuration of downstream signal processing units of a parent device and a child device of an infrastructure sharing compatible DAS provided by four operators (operators A to D). Note that the aggregation device 130 is omitted.
As shown on the left side of FIG. 7, the frequency allocation of operators A to D is in ascending order of operator A, operator B, operator C, and operator D.

As shown in FIG. 7, the downstream signal processing unit of the conventional base unit 4 includes analog circuit units 41a to 41d (sometimes referred to as analog circuit unit 41) corresponding to operators A to D, respectively, A/D conversion units 42a to 42d (sometimes referred to as A/D conversion unit 42), digital signal processing units 43a to 43d (sometimes referred to as digital signal processing unit 43), and a transceiver circuit unit 44.

The analog circuit unit 41 receives downlink signals from the base stations of the corresponding carriers and performs analog processing.
The A/D conversion section 42 converts the analog signal output from the analog circuit section 41 into a digital signal.
The digital signal processing unit 43 includes a digital filter, limits the input digital signal to the band of the corresponding carrier, and performs digital signal processing required for transmission.
The transceiver circuit section 44 integrates the electrical signals from each digital signal processing section 43, converts it into an optical signal, and outputs it to the slave device 3 via an optical cable.

The handset 3 also includes a transceiver circuit section 31, ON/OFF processing sections 32a to 32d (sometimes referred to as ON/OFF processing section 32) provided for each operator, digital signal processing sections 33a to 33d (sometimes referred to as digital signal processing section 33), a digital multiplexing section 34, a D/A conversion section 35, and an analog circuit section 36.

The transceiver circuit section 31 converts the optical signal from the optical cable into an electrical signal, separates it for each carrier's band, and outputs it to the ON/OFF processing sections 32a to 32d.
The ON/OFF processing units 32a to 32d switch ON/OFF of the signal output for each operator, as described above. Signals from businesses set to ON are output to the digital signal processing unit 33, and signals from businesses set to OFF are not output.

The digital signal processing unit 33 performs digital signal processing for each operator.
The digital multiplexing unit 34 multiplexes signals for each carrier that have been subjected to digital signal processing.
The D/A converter 35 converts the multiplexed digital signal into an analog signal.
The analog circuit section 36 performs analog processing such as modulation and amplification on the analog signal.

In the conventional wireless communication system, the signals input from the base stations of each carrier to the base unit 4 are respectively subjected to analog processing in the corresponding analog circuits 41, and then the signals inputted to the base unit 4 from the base stations of each carrier are analog-processed in the corresponding analog circuits 41, and then converted into analog signals in the corresponding A/D converters 42. /D conversion, subjected to digital signal processing in the corresponding digital signal processing section 43, converted into an optical signal by the transceiver circuit section 44, and sent to the slave unit 3.

The optical signal received by the handset 3 is converted into an electrical signal by the transceiver circuit unit 31 and input to the ON/OFF processing unit 32 for each operator, and if the ON/OFF processing unit 32 is set to ON. Only the signal is output to the digital signal processing section 33 and subjected to digital signal processing.
The signal is then multiplexed by the digital multiplexer 34, converted into an analog signal by the D/A converter 35, subjected to analog processing by the analog circuit 36, and sent out from the antenna.

Here, in the conventional base unit 4, the analog circuit 41, the A/D conversion unit 42, and the digital signal processing unit 43 are each configured independently for each operator, and therefore are less susceptible to the influence of signals from other operators using adjacent frequency bands.
Therefore, the signal digitally multiplexed by the slave unit 3 is hardly affected by the signals of other operators, and the quality of the signals of each operator output from the slave unit 3 is good.

[Related technology]
In addition, as a conventional technology of a wireless communication system, there is JP 2014-187450A "Optical Transmission Device" (Patent Document 1).
Patent Document 1 describes an optical transmission device that can reduce optical transmission capacity while satisfying signal standards when performing optical transmission using multiple frequencies.

Japanese Patent Application Publication No. 2014-187450

However, conventional base stations required an A/D converter for each operator, which resulted in increased circuit size and equipment costs.

In addition, Patent Document 1 describes that downlink signals of multiple carriers are analog-combined by one analog combining unit, and that downlink signals of carriers with non-adjacent frequency bands are combined and analog-combined by multiple analog combining units. That is not stated.

The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a parent unit and a wireless communication system that can reduce the circuit scale without degrading the signal quality of downstream signals in a system using an infrastructure sharing-compatible DAS.

In order to solve the problems of the conventional example, the present invention is a base unit used in a distributed antenna system, and includes a plurality of analog circuits that perform analog processing on downlink signals from base stations of each operator, and an analog processing Among the downloaded signals, there are multiple analog combiners that combine downlink signals of carriers whose frequency bands are not adjacent, and the same number of analog combiners that convert the outputs from the multiple analog combiners from analog signals to digital signals. It is characterized by having an A/D converter, a plurality of digital signal processing units that separate digital signals into downlink signals for each carrier, and a transmitting unit that transmits the separated downlink signals as optical signals.

The present invention is also characterized in that the parent unit includes a first analog synthesizer and a second analog synthesizer as the multiple analog synthesizers, and includes a first A/D converter connected to the rear stage of the first analog synthesizer and a second A/D converter connected to the rear stage of the second analog synthesizer as the A/D converters.

The present invention also provides a wireless communication system, which includes any of the base units described above, a processing unit that turns on or off a signal received from the base unit for each carrier, and a processing unit that turns on or off a signal received from the base unit for each carrier. The mobile device is characterized by having a processing unit that performs digital signal processing of signals, and a multiplexing unit that digitally multiplexes signals subjected to digital signal processing for each carrier.

The present invention also provides a master unit used in a distributed antenna system, which includes a plurality of analog circuits that perform analog processing on downlink signals from base stations of each operator, and an analog synthesis circuit that combines the analog-processed downlink signals. an A/D converter that converts the output from the analog synthesizer from an analog signal to a digital signal, a plurality of digital signal processing units that separate the digital signal into downstream signals for each carrier, and It is characterized by having a transmitter that transmits an optical signal.

According to the present invention, a base device used in a distributed antenna system includes a plurality of analog circuits that perform analog processing of downlink signals from base stations of each operator, and a frequency band of the analog-processed downlink signals. a plurality of analog combiners that combine downlink signals of non-adjacent carriers, a number of A/D converters equal to the number of analog combiners that convert the outputs from the plurality of analog combiners from analog signals to digital signals, and a digital signal. The base unit has multiple digital signal processing units that separate the downlink signals for each carrier, and a transmission unit that transmits the separated downlink signals as optical signals. By combining and synthesizing the downlink signals of carriers, it is possible to suppress the influence of frequency components of other carriers on the signals of each carrier separated by the digital signal processing unit, and prevent deterioration of the quality of the downstream signals. Furthermore, the number of A/D converters can be reduced to the same number as the analog synthesizer, thereby reducing the circuit scale.

In addition, according to the present invention, a parent unit used in a distributed antenna system has a plurality of analog circuits that perform analog processing of downstream signals from the base stations of each operator, an analog combiner that combines the analog-processed downstream signals, an A/D converter that converts the output from the analog combiner from an analog signal to a digital signal, a plurality of digital signal processing units that separate the digital signal into downstream signals for each operator, and a transmitting unit that transmits the separated downstream signals as optical signals, which has the effect of reducing the number of A/D converters and significantly reducing the circuit scale.

FIG. 1 is an explanatory diagram showing the configuration of a first wireless communication system. 4 is an explanatory diagram showing an output signal from a slave unit in the first wireless communication system; FIG. FIG. 2 is an explanatory diagram showing the configuration of a second wireless communication system. FIG. 7 is an explanatory diagram showing an output signal from a handset in the second wireless communication system. FIG. 2 is an explanatory diagram showing a configuration example of an infrastructure sharing compatible DAS. FIG. 11 is an explanatory diagram showing an example of operation ON/OFF for each business operator. FIG. 1 is an explanatory diagram showing the configuration of a conventional wireless communication system.

Embodiments of the present invention will be described with reference to the drawings.
[Overview of embodiment]
The base unit (first base unit) according to the first embodiment of the present invention is a base unit used in a distributed antenna system, and is a base unit used in a distributed antenna system. An analog circuit, an analog combiner that combines downlink signals from multiple carriers, an A/D converter that converts the output from the analog combiner into a digital signal, and separates the digital signal into downlink signals for each carrier. It has multiple digital signal processing units and a transmitting unit that transmits separated downlink signals as optical signals, and can significantly reduce the number of A/D converters and reduce circuit scale and equipment cost. It is.

The parent unit (second parent unit) according to the second embodiment of the present invention is a parent unit used in a distributed antenna system, and has a plurality of analog circuits that perform analog processing of downstream signals from base stations for each operator, a plurality of analog combiners that combine downstream signals from operators whose frequency bands are not adjacent, the same number of A/D converters as the analog combiners that convert the output from the plurality of analog combiners into a digital signal, a plurality of digital signal processing units that separate the digital signal into downstream signals for each operator, and a transmission unit that transmits the separated downstream signals as an optical signal.By combining the downstream signals of the plurality of operators so as not to be affected by the signals of other operators and performing A/D conversion on the combined signal, the number of A/D converters can be reduced without degrading the quality of the downstream signal, and this can be realized without implementing a filter with steep filter characteristics in the digital signal processing unit, thereby reducing the cost of the device.

Further, the wireless communication system according to the embodiment of the present invention is a wireless communication system including a first base unit or a second base unit.

[Configuration of wireless communication system according to first embodiment: FIG. 1]
The configuration of a wireless communication system (first wireless communication system) according to a first embodiment of the present invention will be described using FIG. 1. FIG. 1 is an explanatory diagram showing the configuration of a first wireless communication system.
As shown in FIG. 1, the first wireless communication system, like the conventional wireless communication system shown in FIG. 7, is a DAS supporting infrastructure sharing by four operators (operators A to D). Note that the aggregation device 130 is omitted.

Further, as shown at the left end of FIG. 1, the frequency allocation of carriers A to D is in ascending order of carrier A, carrier B, carrier C, and carrier D.
Here, the frequency bands of carriers A and B, carriers B and C, and carriers C and D are adjacent to each other.

As shown in FIG. 1, the first wireless communication system includes a first base unit 1 and a slave unit 3. Here, the configuration of the downlink signal processing section is shown for the first base unit 1 and the handset 3, but since the handset 3 has the same configuration and operation as the conventional handset 3 shown in FIG. , the explanation is omitted.

The first base unit 1, which is a characteristic part of the first wireless communication system, will be specifically described.
The downstream signal processing unit of the first base unit 1 includes analog circuit units 11a, 11b, 11c, and 11d, an analog synthesis unit 12, digital signal processing units 14a, 14b, 14c, and 14d, digital signal processing units 14a, 14b, 14c, and 14d, and a transceiver circuit unit 15.

Analog circuit units 11a to 11d are provided corresponding to carriers A to D, respectively, as in the past, and perform analog processing on signals input from the base station 100 of each carrier. The analog circuit sections 11a to 11d are sometimes referred to as an analog circuit section 11.

The analog synthesis section 12 is a characteristic part of the first base unit 1, and inputs and synthesizes analog signals output from the analog circuit sections 11a to 11d. That is, all analog-processed signals from carriers A to D are combined and output to the A/D converter 13.

The A/D converter 13 receives the composite signal output from the analog synthesizer 12, converts it into a digital signal, and outputs the digital signal.
Therefore, in the first base unit 1, the number of analog synthesis sections 12 and A/D conversion sections 13 is only one, and the number can be significantly reduced compared to the conventional one, and the circuit scale can be reduced. It is.

The digital signal processing units 14a to 14d receive the digital signals branched after A/D conversion by the A/D conversion unit 13, and separate and extract data of the corresponding carrier bands using digital filters. The digital signal processing units 14a to 14d may also be referred to as a digital signal processing unit 14.
The transceiver circuit section 44 receives a digital signal, converts it into an optical signal, and transmits it to the slave unit 3 in the same manner as in the conventional case. The transceiver circuit section 44 corresponds to a transmitting section recited in the claims.

The operation of the first base unit 1 will be explained.
Signals output from the base stations 100 of carriers A to D are input to analog circuits 41a to 41d, where analog processing is performed, and synthesized by analog synthesis section 12 to generate an analog composite signal. Ru.
In other words, the analog composite signal in the first base unit 1 is a combination of downlink signals of four carriers, carriers A to D.

The analog composite signal is converted from an analog signal to a digital signal by the A/D converter 13, branched, and input to the digital signal processing sections 14a to 14d.
Then, in the digital signal processing units 14a to 14d, the frequency bands of the corresponding operators are separated by digital filters, and the signals are converted into optical signals by the transceiver circuit unit 15 and transmitted to the slave unit 3 via an optical cable.

In the handset 3, processing is carried out in the same manner as before, and the optical signal received by the transceiver circuit 31 is converted into an electrical signal, multiplexed by the ON/OFF processing unit 32 corresponding to each operator and the digital multiplexing unit 34, converted into an analog signal by the D/A conversion unit 35, analog processing is carried out by the analog circuit unit 36, and the signal is sent out from the antenna.

The digital signal processing unit 14 of the first base unit 1 performs A/D conversion and digital processing on a composite signal that is an analog composite of signals from multiple operators with adjacent frequency bands. This makes it difficult to completely remove the signal components of the adjacent operators, and the digital multiplexing unit 34 of the handset 3 combines the signals while leaving the frequency components of the adjacent operators, resulting in a deterioration of signal quality.

[Output signal from the handset in the first wireless communication system: Figure 2]
The signals output from the handset 3 in the first wireless communication system will be explained using FIG. 2. FIG. 2 is an explanatory diagram showing output signals from slave units in the first wireless communication system.
As shown in FIG. 2, the frequency bands of carriers A and B, carriers B and C, and carriers C and D are adjacent to each other. Here, since the operation of the operator C is OFF, the signal of the operator C is not output from the handset 3.

However, with the frequency separation in the digital processing of the first base unit 1, it is difficult to completely remove adjacent frequency components, so in the slave unit 3, the influence of adjacent frequency components is reduced as shown in FIG. It will be synthesized in the remaining state.
Therefore, in the first wireless communication system, the quality of the downlink signal of each carrier from the handset 3 deteriorates due to the influence of the frequency components of other neighboring carriers.

In order to prevent degradation of signal quality in the configuration of the first base unit 1 and the first wireless communication system, it is necessary to implement a digital filter with steep filter characteristics in the digital signal processing unit 14 so as to completely remove the frequency components of adjacent operators, but this is difficult in terms of circuit size and cost.

[Configuration of wireless communication system according to second embodiment: FIG. 3]
A wireless communication system (second wireless communication system) according to a second embodiment will be described using FIG. 3. FIG. 3 is an explanatory diagram showing the configuration of the second wireless communication system.
As shown in FIG. 3, the second wireless communication system uses a base unit (second base unit) 2 according to the second embodiment instead of the first base unit 1 in the first wireless communication system. This is a DAS that supports infrastructure sharing. Note that the handset 3 is the same as the conventional and first wireless communication system.

The second wireless communication system reduces the circuit scale of the base unit compared to the conventional system and prevents deterioration of the quality of the downlink signal output from the slave unit.
In the first base unit 1 described above, signal quality deteriorates due to adjacent frequency components influencing each other because the signals of carriers with adjacent frequency bands are synthesized in analog form. In 2, signals from carriers whose frequency bands are not adjacent are combined for analog synthesis to prevent quality deterioration.

In the example of FIG. 3, as shown on the left, the frequency bands of carriers A and C, and carriers B and D are not adjacent to each other. The downstream signals of operator C, operator B, and operator D are analog-combined.

As shown in FIG. 3, the downlink signal processing section of the second base unit 2 includes analog circuit sections 21a, 21c, 21b, and 21d, analog synthesis sections 22a and 22b, and A/D conversion sections 23a and 23b. It includes digital signal processing units 24a, 24c, 24b, and 24d and a transceiver circuit 25.

Analog circuit units 21a, 21c, 21b, and 21d have the same configuration and operation as analog circuit units 11a, 11c, 11b, and 11d of first base unit 1, respectively, and perform analog processing by inputting downstream signals from base stations of operators A, C, B, and D, respectively.

The analog synthesis unit 32a synthesizes the output signals from the analog circuit unit 21a and the analog circuit unit 21c. As described above, the frequency band of the operator A and the frequency band of the operator C are not adjacent to each other.
The analog synthesis unit 32b synthesizes the output signals from the analog circuit unit 21b and the analog circuit unit 21d. The frequency band of the operator B and the frequency band of the operator D are not adjacent to each other.

The A/D converter 23a converts the synthesized analog signal output from the analog synthesizer 32a into a digital signal.
The A/D converter 23b converts the synthesized analog signal output from the analog synthesizer 32b into a digital signal.
As a result, in the second base unit 2, the number of analog synthesis sections and A/D conversion sections, which were conventionally required to be the same number as the number of carriers (four in this case), can be significantly reduced to two each.

The digital signal processing unit 24a uses a digital filter to separate data in the frequency band of carrier A from the digital signal outputted from the A/D conversion unit 23a and branched.

Here, since the frequency band of operator A and the frequency band of operator C are not adjacent, when separating and extracting data of the frequency band of operator A from the output signal from the A/D conversion unit 23a, there is little influence from the signal of operator C.
Therefore, even if the digital filter of the digital signal processing unit 24a does not have a particularly steep filter characteristic, it is sufficient to remove signals from other operators (here, operator C), thereby making it possible to reduce circuit size and costs.

Similarly, the digital signal processing unit 24c separates the data of the frequency band of operator C from the digital signal from the A/D conversion unit 23a. The digital signal processing unit 24c can also easily separate the data of operator C without using a digital filter with very steep filter characteristics, since there is no signal of another operator (here, operator A) in the adjacent frequency band.

The same applies to the digital signal processing section 24b and the digital signal processing section 24d, and since the frequency bands of carriers B and D are not adjacent to each other, the digital signal obtained by A/D converting the synthesized analog signal is converted into a digital signal. The signal processing unit 24b is capable of separating data in the frequency band of operator B, and the digital signal processing unit 24d is capable of separating data in the frequency band of operator D, without mixing frequency components of other operators.

In this way, in the second base unit 2, the analog synthesis section 22 synthesizes the downlink signals of carriers in frequency bands that are not adjacent to each other (there are gaps), and the digital signal processing section 24 synthesizes the downlink signals of each carrier. This allows the data of each frequency band to be separated with high accuracy without the signals of carriers influencing each other.

As a result, in the handset 3, the signals multiplexed by the digital multiplexing section 24 are multiplexed with signals that are not influenced by other carriers, so the signals are sent out from the handset 3 compared to the first wireless communication system. The quality of the downlink signal can be improved, and the signal quality can be maintained compared to the conventional method.

[Output signal from slave unit in second wireless communication system: Figure 4]
The signals output from the handset 3 in the second wireless communication system will be explained using FIG. 4. FIG. 4 is an explanatory diagram showing output signals from slave devices in the second wireless communication system.
Figure 4 shows an example where the operation of operator C is suspended, but the signals of operator A, operator B, and operator D are output with good quality without being affected by neighboring operators. ing.

In this way, in the second wireless communication system using the second base unit 2, the number of A/D converters is reduced compared to the conventional system, and the circuit scale of the base unit is reduced, while the downlink signal from the slave unit is It is possible to maintain good quality.

[Effects of the embodiment]
The first base unit and the first wireless communication system have a plurality of analog circuits 11a to 11d that perform analog processing of downstream signals from the base stations of each operator, an analog combiner 12 that combines the downstream signals of the multiple operators, an A/D converter 13 that converts the output from the analog combiner 12 into a digital signal, a plurality of digital signal processing units 14a to 14d that separate the digital signal into downstream signals for each operator, and a transceiver circuit 15 that transmits the separated downstream signals as optical signals, and have the effect of significantly reducing the number of A/D converters 13 and reducing the circuit size and device costs.

The second base unit and the second wireless communication system include analog circuits 21a-21d that perform analog processing of downstream signals from the base stations of each operator, analog combiners 22a, 22b that combine and synthesize downstream signals from operators whose frequency bands are not adjacent, A/D converters 24a, 24b that convert the output from the analog combiners 22a, 22b into a digital signal, multiple digital signal processing units 24a-24d that separate the digital signal into downstream signals for each operator, and a transceiver circuit 25 that transmits the separated downstream signals as optical signals. By synthesizing the downstream signals of multiple operators so as not to be affected by the signals of other operators and performing A/D conversion on the synthesized signal, the number of A/D converters can be reduced without degrading the quality of the downstream signals, and the circuit scale can be reduced. This can also be achieved without implementing a filter with steep filter characteristics in the digital signal processing unit, which has the effect of reducing the cost of the device.

The present invention is suitable for a parent unit of a distributed antenna system and a wireless communication system that can reduce the circuit scale without degrading the signal quality of the downstream signal output from the child unit.

1...First base unit, 2...Second base unit, 3,130...Slave unit, 4...Conventional base unit, 11,21,41,36...Analog circuit unit, 12,22,42...Analog synthesis unit, 13,23,43...A/D conversion unit, 14,24,33,44...Digital signal processing unit, 15,25,31...Transceiver circuit unit, 32...ON/OFF control unit, 34...Digital multiplexing unit, 35...D/A conversion unit, 100...Base station, 110...Base unit, 120...Aggregation device, 140...Wireless terminal device

Claims (4)

A base unit used in a distributed antenna system,
Multiple analog circuits that perform analog processing on downlink signals from base stations of each operator,
a plurality of analog synthesizers that combine downlink signals of carriers whose frequency bands are not adjacent among the analog-processed downlink signals;
the same number of A/D converters as the analog synthesizers that convert outputs from the plurality of analog synthesizers from analog signals to digital signals;
a plurality of digital signal processing units that separate the digital signal into downlink signals for each of the vendors;
A base unit comprising: a transmitter that transmits the separated downlink signal as an optical signal. The plurality of analog synthesizers include a first analog synthesizer and a second analog synthesizer,
As an A/D converter, a first A/D converter connected after the first analog synthesizer, and a second A/D converter connected after the second analog synthesizer. The parent device according to claim 1, further comprising: A base unit according to claim 1 or 2,
a processing unit that turns on or off the signal received from the base unit for each operator; a processing unit that performs digital signal processing on the signal turned on by the processing unit for each operator; and a processing unit that processes the digital signal for each operator. a slave device comprising a multiplexing unit that digitally multiplexes the processed signal;
A wireless communication system comprising: A master unit for use in a distributed antenna system, comprising:
A plurality of analog circuits for analog processing of downstream signals from base stations of each carrier;
an analog combiner for combining the analog-processed downstream signals;
an A/D converter for converting the output from the analog synthesizer from an analog signal to a digital signal;
A plurality of digital signal processing units that separate the digital signal into downstream signals for each of the service providers;
a transmitting section for transmitting the separated downstream signal as an optical signal.

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