Base unit and wireless communication system

Abstract

To provide a master unit and a wireless communication system that can reduce a circuit size in a distributed antenna system without degrading signal quality of a downlink signal.SOLUTION: A master unit includes: analog circuits 21a to 21d for analog processing of downlink signals from base stations of respective business operators; analog synthesizers 22a and 22b for synthesizing by combining downlink signals of business operators whose frequency bands are not adjacent; A / D converters 24a and 24b for converting output from the analog synthesizers 22a and 22b into digital signals; a plurality of digital signal processing units 24a to 24d for separating the digital signals into downlink signals for the business operators; and a transceiver circuit 25 for transmitting the separated downlink signals using optical signals. The master unit and a wireless communication system are designed to combine the downlink signals of the plurality of business operators so as to avoid the influence of signals of other business operators.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a master unit and a wireless communication system of a distributed antenna system, and more particularly to a master unit and a wireless communication system that can reduce the circuit scale without degrading the signal quality of a downstream signal output from a slave unit. [Background technology]

[0002] Description of the Prior Art In closed spaces such as inside buildings and tunnels, multi-operator DAS (Distributed Antenna Systems) are becoming more common. Multi-operator DAS (infrastructure sharing compatible DAS) transmits and receives radio waves from multiple operators.

[0003] [Example of infrastructure sharing compatible DAS configuration: Figure 5] An example of the configuration of an infrastructure sharing compatible DAS will be described with reference to Fig. 5. Fig. 5 is an explanatory diagram showing an example of the configuration of an infrastructure sharing compatible DAS. The infrastructure sharing compatible DAS comprises a parent device (parent device #1 in the figure) 110 that transmits and receives data with base stations 100 of multiple operators, a plurality of aggregation devices 120 (aggregation #1 to aggregation #M in the figure) connected to the parent device 110 by optical cables, and a plurality of slave devices 130 (slave devices #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 base stations 100 of operators.

[0004] 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 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 determined according to the frequency allocation (number of wireless signal bands) supported by each operator and the number of MIMO (Multiple-Input and Multiple-Output) devices.

[0005] The aggregation device 120 connects the parent device 110 and multiple child devices 130 via an optical cable to perform data communication. The aggregation device 120 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.

[0006] The slave device 130 is connected to the aggregation device 120 via an optical cable, converts the optical signal from the aggregation device 120 into a wireless signal, and outputs it from an antenna. The slave device 130 also converts the wireless signal received by the antenna into an optical signal and outputs it 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.) within a building, and perform wireless communication with wireless terminal devices 140 of multiple operators. Fig. 5 shows a configuration in which N slave devices 130 are connected to M aggregation devices 120, respectively.

[0007] 5 shows wireless terminal device 140a of operator A and wireless terminal device 140d of operator D. By using a DAS shared by multiple operators, wireless terminal devices 140 of multiple operators located in a building or the like can transmit and receive data via a shared slave device 130.

[0008] [Example of infrastructure sharing compatible DAS operation] For example, an infrastructure sharing compatible DAS with four operators and 32 terminals may be configured with four operators' base stations 100, one base station 110, four aggregation devices 120, and 32 terminals 130, with eight terminals 130 connected to each aggregation device 120.

[0009] Furthermore, when an infrastructure sharing compatible DAS is constructed in a building, one to several slave units 130 are placed on each floor, and there are cases where one system is assigned to multiple floors of multiple buildings. In infrastructure sharing, it is necessary to control the operation of each business operator on a building or floor basis, and each slave unit 130 controls the operation (ON) / stop (OFF) of each business operator.

[0010] [Example of operator-specific operation ON / OFF: Figure 6] An example of operation ON / OFF for each business operator in an infrastructure sharing compatible DAS will be described with reference to Fig. 6. Fig. 6 is an explanatory diagram showing an example of operation ON / OFF for each business operator. FIG. 6 shows downstream signal output when an infrastructure sharing compatible DAS equipped with the above-mentioned 32 slave devices 130 (slave devices #1 to #32) is set up so that each slave device is operated on a per-service provider basis.

[0011] Of the 32 sub-units 130, sub-units #1 to #6 are set to operate ON for all of operators A, B, C, and D, and the downstream signals from sub-units #1 to #6 output the frequencies of all operators as shown in Figure 6(a).

[0012] For handset #7 to handset #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 handset devices output frequencies corresponding to operators A, B, and D, but output of the frequency corresponding to operator C is stopped.

[0013] Handset #19 to handset #24 are set to operation ON for operators A and C, and to operation OFF for operators B and D, and as shown in Figure 6(c), frequencies corresponding to operators A and C are output, but frequencies corresponding to operators B and D are not output.

[0014] Handset #25 to handset #32 are set to operate ON for operators B and C, and are set to operate OFF for operators A and D, and only frequencies corresponding to operators B and C are output, as shown in Figure 6(d). In this way, the operations of the business operators are controlled on a building-by-building or floor-by-floor basis.

[0015] [Configuration of a conventional wireless communication system: Figure 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 the downstream signal processing units of the master and slave units of the 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.

[0016] 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 units 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.

[0017] The analog circuit unit 41 receives downstream signals from the base stations of the corresponding carriers and performs analog processing. The A / D conversion unit 42 converts the analog signal output from the analog circuit unit 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 unit 44 integrates the electrical signals from the digital signal processors 43, converts them into optical signals, and outputs them to the slave unit 3 via an optical cable.

[0018] The slave unit 3 also includes a transceiver circuit unit 31, ON / OFF processing units 32a to 32d (sometimes referred to as ON / OFF processing units 32) provided for each operator, digital signal processing units 33a to 33d (sometimes referred to as digital signal processing units 33), a digital multiplexing unit 34, a D / A conversion unit 35, and an analog circuit unit 36.

[0019] The transceiver circuit unit 31 converts the optical signal from the optical cable into an electric signal, separates it for each band of the operator, and outputs it to the ON / OFF processing units 32a to 32d. As described above, the ON / OFF processing units 32a to 32d switch ON / OFF of the signal output for each operator. Signals of operators that are set to ON are output to the digital signal processing unit 33, and signals of operators that are set to OFF are not output.

[0020] The digital signal processing unit 33 performs digital signal processing for each operator. The digital multiplexing unit 34 multiplexes the signals for each operator 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.

[0021] In a conventional wireless communication system, signals input to the base station 4 from each operator's base station are each subjected to analog processing by a corresponding analog circuit 41, A / D conversion by a corresponding A / D conversion unit 42, digital signal processing by a corresponding digital signal processing unit 43, conversion into an optical signal by a transceiver circuit unit 44, and sent to the handset 3.

[0022] The optical signal received by the slave unit 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 only when ON is set in the ON / OFF processing unit 32 is the signal output to the digital signal processing unit 33 where digital signal processing is performed. The signals are then multiplexed by a digital multiplexing unit 34, converted into analog signals by a D / A conversion unit 35, subjected to analog processing by an analog circuit unit 36, and transmitted from an antenna.

[0023] Here, in the conventional base unit 4, the analog circuit 41, A / D conversion unit 42, and 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 signals digitally multiplexed by the slave device 3 are hardly affected by signals from other operators, and the quality of the signals from each operator output from the slave device 3 is good.

[0024] [Related Technology] Incidentally, a conventional technology for a wireless communication system is disclosed in Japanese Patent Laid-Open Publication No. 2014-187450 entitled "Optical Transmission Device" (Patent Document 1). Patent Document 1 describes an optical transmission device that can reduce the optical transmission capacity while satisfying the signal standards when optically transmitting using multiple shared frequencies. [Prior art documents] [Patent documents]

[0025] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-187450 Summary of the Invention [Problem to be solved by the invention]

[0026] However, in conventional base units, an A / D converter is provided for each operator, which increases the circuit size and device costs.

[0027] Incidentally, Patent Document 1 does not describe analog synthesis of downstream signals from multiple operators using a single analog synthesis unit, or combining downstream signals from operators whose frequency bands are not adjacent and analog synthesis using multiple analog synthesis units.

[0028] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a base unit and a wireless communication system that can reduce the circuit scale without degrading the signal quality of the downstream signal in a system using an infrastructure sharing compatible DAS. [Means for solving the problem]

[0029] The present invention, which solves the problems of the above-mentioned conventional example, is a master unit used in a distributed antenna system, and comprises a plurality of analog circuits that perform analog processing of downstream signals from base stations of each operator, a plurality of analog combiners that combine the analog-processed downstream signals of operators whose frequency bands are not adjacent, and a circuit that converts the outputs from the plurality of analog combiners from analog signals to digital signals. Analog Synthesizer It is characterized by having the same number of A / D converters as the number of operators, multiple digital signal processing units that separate the digital signals into downstream signals for each operator, and a transmission unit that transmits the separated downstream signals as optical signals.

[0030] The present invention is also characterized in that the parent unit includes a first analog combiner and a second analog combiner as the multiple analog combiners, and a first A / D converter connected to a stage subsequent to the first analog combiner and a second A / D converter connected to a stage subsequent to the second analog combiner as the A / D converters.

[0031] The present invention is also characterized by a wireless communication system having any of the above-mentioned base units, and a sub-unit including a processing unit that turns on or off signals received from the base unit for each operator, a processing unit that performs digital signal processing of signals turned on by the processing unit for each operator, and a multiplexing unit that digitally multiplexes the signals that have been digitally signal processed for each operator. [Effects of the Invention]

[0033] According to the present invention, a master unit used in a distributed antenna system includes a plurality of analog circuits that perform analog processing of downstream signals from base stations of respective operators, a plurality of analog combiners that combine the analog-processed downstream signals of operators whose frequency bands are not adjacent, and a circuit that converts the outputs from the plurality of analog combiners from analog signals to digital signals. Analog Synthesizer The base unit has the same number of A / D converters as the operators, multiple digital signal processing units that separate the digital signals into downstream signals for each operator, and a transmission unit that transmits the separated downstream signals as optical signals.Therefore, by using an analog combiner to combine downstream signals from operators that do not have adjacent frequency bands, it is possible to suppress the influence of frequency components from other operators on the signals for each operator separated by the digital signal processing unit, thereby preventing deterioration in the quality of the downstream signals, and further has the effect of reducing the number of A / D converters to the same number as the analog combiners, thereby reducing the circuit size. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 is an explanatory diagram showing the configuration of a first wireless communication system. [Figure 2] FIG. 2 is an explanatory diagram showing an output signal from a slave device in the first wireless communication system. [Figure 3] FIG. 10 is an explanatory diagram showing the configuration of a second wireless communication system. [Figure 4] FIG. 10 is an explanatory diagram showing an output signal from a slave device in the second wireless communication system. [Figure 5] FIG. 1 is an explanatory diagram showing an example of the configuration of an infrastructure sharing compatible DAS. [Figure 6] FIG. 10 is an explanatory diagram showing an example of operation ON / OFF for each business operator. [Figure 7] FIG. 1 is an explanatory diagram showing the configuration of a conventional wireless communication system. DETAILED DESCRIPTION OF THE INVENTION

[0036] An embodiment of the present invention will be described with reference to the drawings. [Outline of the embodiment] The base station (first base station) according to the first embodiment of the present invention is a base station 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, an analog combiner that combines the downstream signals of the multiple operators, an A / D converter that converts the output from the analog combiner into 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 an optical signal, thereby enabling a significant reduction in the number of A / D converters and reducing the circuit size and device costs.

[0037] In addition, a base station (second base station) according to a second embodiment of the present invention is a base station used in a distributed antenna system, and has a plurality of analog circuits that perform analog processing of downlink signals from base stations for each operator, a plurality of analog combiners that combine downlink 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 digital signals, a plurality of digital signal processing units that separate the digital signals into downlink signals for each operator, and a transmitting unit that transmits the separated downlink signals as optical signals.By combining the downlink signals of multiple operators so as not to be affected by signals from 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 downlink signals, and this can be realized without implementing a filter with steep filter characteristics in the digital signal processing unit, thereby reducing equipment costs.

[0038] Moreover, the wireless communication system according to the embodiment of the present invention is a wireless communication system including a first master unit or a second master unit.

[0039] [Configuration of a wireless communication system according to a 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 with reference to Fig. 1. Fig. 1 is an explanatory diagram showing the configuration of the first wireless communication system. As shown in Fig. 1, the first wireless communication system is an infrastructure sharing compatible DAS provided by four operators (operators A to D), similar to the conventional wireless communication system shown in Fig. 7. Note that the aggregation device 130 is omitted.

[0040] As shown on the left side of FIG. 1, the frequency allocation of operators A to D is in ascending order of operator A, operator B, operator C, and operator D. Here, the frequency bands of operators A and B, operators B and C, and operators C and D are adjacent to each other.

[0041] As shown in Fig. 1, the first wireless communication system includes a first base station 1 and a handset 3. Here, the configuration of the downlink signal processing section of the first base station 1 and the handset 3 is shown, but the handset 3 has the same configuration and operation as the conventional handset 3 shown in Fig. 7, so a description thereof will be omitted.

[0042] 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.

[0043] Analog circuit units 11a to 11d are provided corresponding to operators A to D, respectively, as in the conventional case, and perform analog processing on signals input from the base station 100 of each operator. Analog circuit units 11a to 11d may also be referred to as analog circuit unit 11.

[0044] The analog synthesis unit 12 is a characteristic part of the first base unit 1, and receives and synthesizes the analog signals output from the analog circuit units 11a to 11d. That is, the analog synthesis unit 12 synthesizes all of the analog-processed signals of the operators A to D and outputs the result to the A / D conversion unit 13.

[0045] The A / D converter 13 receives the composite signal output from the analog composite unit 12, converts it into a digital signal, and outputs it. Therefore, in the first base unit 1, only one analog synthesis unit 12 and one A / D conversion unit 13 are required, which is a significant reduction in number compared to the conventional art, and allows for a reduction in circuit scale.

[0046] 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 in the bands of the corresponding operators using digital filters. The digital signal processing units 14a to 14d may also be referred to as digital signal processing unit 14. The transceiver circuit unit 44 receives a digital signal, converts it into an optical signal, and sends it to the slave unit 3, in the same manner as in the past. The transceiver circuit unit 44 corresponds to a transmitting unit as claimed.

[0047] The operation of the first base unit 1 will now be described. The signals output from the base stations 100 of the operators A to D are input to the analog circuits 41a to 41d, respectively, where they are subjected to analog processing, and then combined in the analog combiner 12 to generate an analog combined signal. That is, the analog composite signal in first base unit 1 is a composite of downstream signals from four operators, operators A to D.

[0048] The analog composite signal is converted from an analog signal to a digital signal by A / D converter 13, branched, and input to 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.

[0049] In the slave unit 3, processing is carried out in the same manner as in the past, and the optical signal received by the transceiver circuit 31 is converted into an electrical signal, which is then 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, subjected to analog processing by the analog circuit unit 36, and sent out from the antenna.

[0050] Here, 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, so it is difficult to completely remove the signal components of adjacent operators, and the digital multiplexing unit 34 of the handset 3 ends up combining the signals while leaving the frequency components of adjacent operators, resulting in a deterioration in signal quality.

[0051] [Output signal from the slave device in the first wireless communication system: Figure 2] The signal output from the slave device 3 in the first wireless communication system will be described with reference to Fig. 2. Fig. 2 is an explanatory diagram showing the signal output from the slave device in the first wireless communication system. 2, the frequency bands of operators A and B are adjacent, operators B and C are adjacent, and operators C and D are adjacent. Here, since the operation of operator C is OFF, the signal of operator C is not output from handset 3.

[0052] However, since it is difficult to completely remove adjacent frequency components in the frequency separation performed by the digital processing of the first base unit 1, the adjacent frequency components are combined in the slave unit 3 while retaining their influence, as shown in Figure 2. Therefore, in the first wireless communication system, the quality of the downlink signal of each operator from the slave device 3 is degraded due to the influence of the frequency components of other adjacent operators.

[0053] 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 remove all frequency components of adjacent operators, but this is difficult in terms of circuit size and cost.

[0054] [Configuration of a wireless communication system according to the second embodiment: FIG. 3] A wireless communication system according to a second embodiment (second wireless communication system) will be described with reference to Fig. 3. Fig. 3 is an explanatory diagram showing the configuration of the second wireless communication system. 3, the second wireless communication system is an infrastructure sharing compatible DAS in which a base station (second base station) 2 according to the second embodiment is provided instead of the first base station 1 in the first wireless communication system. Note that the slave station 3 is the same as in the conventional and first wireless communication systems.

[0055] The second wireless communication system reduces the circuit scale of the master unit compared to the conventional system, and prevents degradation in the quality of downstream signals output from the slave units. In the first base unit 1 described above, signals from operators with adjacent frequency bands are combined in an analog manner, which causes adjacent frequency components to affect each other and degrade signal quality. However, in the second base unit 2, signals from operators with non-adjacent frequency bands are combined in an analog manner, thereby preventing quality degradation.

[0056] In the example of Figure 3, as shown on the left side, the frequency bands of operators A and C, and operators B and D are not adjacent, so the second base unit 2 analog-combines the downstream signals of operators A and C, and operators B and D.

[0057] As shown in Figure 3, the downstream signal processing unit of the second base unit 2 includes analog circuit units 21a, 21c, 21b, and 21d, analog synthesis units 22a and 22b, A / D conversion units 23a and 23b, digital signal processing units 24a, 24c, 24b, and 24d, and a transceiver circuit 25.

[0058] 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 input downstream signals from base stations of operators A, C, B, and D, respectively, and perform analog processing.

[0059] 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.

[0060] The A / D converter 23a converts the combined analog signal output from the analog combiner 32a into a digital signal. The A / D converter 23b converts the combined analog signal output from the analog combiner 32b into a digital signal. As a result, in the second base unit 2, the number of analog synthesis units and A / D conversion units that were previously required to be the same as the number of operators (four in this case) can be significantly reduced to two each.

[0061] The digital signal processing unit 24a separates data in the frequency band of the operator A from the branched digital signal output from the A / D conversion unit 23a using a digital filter.

[0062] 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, the digital filter of the digital signal processing unit 24a does not need to have a particularly steep filter characteristic to sufficiently remove signals from other operators (here, operator C), thereby reducing the circuit size and costs.

[0063] Similarly, the digital signal processing unit 24c separates data in the frequency band of the 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 the operator C without using a digital filter with a particularly steep filter characteristic, since there is no signal of another operator (in this case, operator A) in the adjacent frequency band.

[0064] The same is true for digital signal processing units 24b and 24d. Since the frequency bands of operators B and D are not adjacent, digital signal processing unit 24b can separate data in the frequency band of operator B from the digital signal obtained by A / D converting the synthesized analog signal, and digital signal processing unit 24d can separate data in the frequency band of operator D from the digital signal without mixing with frequency components of other operators.

[0065] In this way, in the second base unit 2, the analog synthesis unit 22 synthesizes downstream signals from operators in frequency bands that are not adjacent to each other (leaving gaps), so that the digital signal processing unit 24 can accurately separate the data in each frequency band without the signals from each operator affecting each other.

[0066] As a result, in the handset 3, the signals multiplexed by the digital multiplexing unit 24 are signals that are not affected by other operators, so the quality of the downstream signals sent from the handset 3 can be improved compared to the first wireless communication system, and signal quality can be maintained compared to the conventional system.

[0067] [Output signal from the slave device in the second wireless communication system: Figure 4] The signal output from the slave device 3 in the second wireless communication system will be described with reference to Fig. 4. Fig. 4 is an explanatory diagram showing the signal output from the slave device in the second wireless communication system. Figure 4 shows an example in which the operation of operator C is stopped, but the signals of operators A, B, and D are output with good quality without being affected by neighboring operators.

[0068] In this way, in the second wireless communication system using the second base unit 2, it is possible to reduce the A / D conversion unit compared to conventional systems, thereby reducing the circuit size of the base unit, while maintaining good quality of the downstream signal from the handset.

[0069] [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 the respective operators, an analog combiner 12 that combines the downstream signals of the plurality of 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 the respective operators, 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.

[0070] Furthermore, the second base unit and the second wireless communication system include analog circuits 21a to 21d that perform analog processing of downlink signals from the base stations of each operator, analog combiners 22a, 22b that combine and synthesize downlink signals from 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 to 24d that separate the digital signals into downlink signals for each operator, and a transceiver circuit 25 that transmits the separated downlink signals as an optical signal, and by synthesizing the downlink signals of multiple operators so as not to be affected by signals from other operators and performing A / D conversion on the synthesized signal, it is possible to reduce the number of A / D converters and thereby reduce the circuit size without degrading the quality of the downlink signals, and it is also possible to achieve this 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. [Industrial Applicability]

[0071] The present invention is suitable for a master unit of a distributed antenna system and a wireless communication system, which can reduce the circuit scale without degrading the signal quality of a downstream signal output from a slave unit. [Explanation of symbols]

[0072] REFERENCE SIGNS LIST 1...first base unit, 2...second base unit, 3,130...child 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

1. A master unit used in a distributed antenna system, comprising: a plurality of analog circuits for analog processing of downstream signals from base stations of respective carriers; a plurality of analog combiners for combining downstream signals of operators whose frequency bands are not adjacent to each other among the downstream signals that have been subjected to the analog processing; A / D converters, the number of which is equal to the number of the analog combiners, for converting outputs from the plurality of analog combiners from analog signals to digital signals; a plurality of digital signal processing units that separate the digital signal into downstream signals for each of the operators; a transmitter that transmits the separated downstream signal as an optical signal.

2. the plurality of analog combiners include a first analog combiner and a second analog combiner; 2. The base unit according to claim 1, further comprising: a first A / D converter connected to a stage subsequent to the first analog combiner; and a second A / D converter connected to a stage subsequent to the second analog combiner.

3. a base unit according to claim 1 or 2; a slave unit including a processing unit that turns on or off signals received from the master unit for each operator, a processing unit that performs digital signal processing of the signals that have been turned on by the processing unit for each operator, and a multiplexing unit that digitally multiplexes the signals that have been digitally processed for each operator; A wireless communication system comprising:

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