JP6691448B2 - Distributed antenna device - Google Patents

Description

  The present invention relates to a distributed antenna device.

  In a mobile communication system, a distributed antenna device is used for the purpose of taking measures against a blind area and expanding the area. Generally, a distributed antenna device is composed of a master unit, a relay unit, and a slave unit. In base station transmission (downlink), the radio frequency signal of the base station device is input to the master unit, the master unit transmits the signal to the slave unit via the relay unit, and the radio frequency signal is transmitted from the antenna connected to the slave unit. Is emitted. In the base station reception (uplink), the reverse route is followed.

A coaxial cable may be used between the parent device, the relay device, and the child device, an optical fiber cable may be used, and a LAN cable may be used. Since the coaxial cable transmits a radio frequency signal, the power is attenuated in proportion to the cable length and is not suitable for long-distance transmission. In the case of an optical fiber cable, if the transmission method is analog transmission (a radio frequency signal is directly modulated by optical intensity transmission), it is possible to transmit about 1 km, but a laser diode with a large dynamic range is required. There is a problem that the signal deteriorates in proportion to the length. When the transmission method is digital transmission (frequency conversion of radio frequency signal to intermediate frequency, conversion to digital signal by analog-digital converter and transmission), error correction is applied to the digital signal and constant bit error rate If the following is allowed, transmission of several tens of km becomes possible. Also, a laser diode that is cheaper than that used for analog transmission can be used. Although a digital signal is used in the case of a LAN cable, it can transmit only about 100 m.

FIG. 11 shows the prior art.
The base station device 101 is connected to the master device 200 via the coaxial cable 102. The master unit 200 is connected to the slave unit 3n0 from the slave unit 310 via an optical fiber cable. Each of the child devices 310 to 3n0 has an antenna.

Patent No. 5411609

  However, in the related art, since the coaxial cable or the optical fiber cable is used as the transmission medium between the devices, the device can be installed only in the place where the transmission medium can be installed. Therefore, for example, when a transmission medium cannot be installed between the devices, or a place where it is difficult to install (for example, when there is a river between the devices or when a downstream device is installed in an adjacent building, there is an obstacle in installing the transmission medium). ) Can not install the device.

Further, when using an optical fiber, the bandwidth is limited by the data rate of the optical module, and when using the coaxial cable 102, power efficiency is lowered due to attenuation of a radio frequency signal.

Generally, commercial power can be obtained relatively easily regardless of whether it is outdoors or indoors (it does not need to be supplied from an upstream device and can be taken near the installation site).

  On the other hand, there are cases where a wireless relay device is used for the purpose of taking measures against the non-sensing area or expanding the area. The wireless relay device converts the radio frequency signal into a digital signal once, performs digital signal processing such as interference cancellation, and converts it again into a radio frequency signal for transmission, and a radio frequency signal is directly amplified by an amplifier. There is a non-reproduction method that transmits the data. Since the former performs digital signal processing, it is possible to suppress signal deterioration and radio signal interference for transmission, and the latter causes signal deterioration due to the characteristics of the amplifier. However, since the former has a digital signal processing unit in addition to the amplifier, the device size becomes large and the cost also becomes high. In addition, delay occurs in the device due to signal processing in the digital signal processing unit.

  A distributed antenna device (100) according to claim 1 of the present invention is a distributed antenna device (100) for a mobile communication system, wherein the antenna distributed device (100) includes an input / output terminal (201A) and a master unit side. A master unit (200) having an antenna (206) and a slave unit (310-3n0) having a plurality of slave unit side antennas (311A-3n2A) are provided, and the master unit side antenna (206A) has two or more beams. The slave unit (310-3n0) has a beam forming unit (205) including a former, and the slave unit (310-3n0) receives a radio frequency signal from the master unit (200) at one slave unit-side antenna (311-3n1A). A signal transmitting unit (311-314) that amplifies and transmits a radio frequency signal from the other handset-side antenna (311A-3n1A) and the other handset-side antenna (312A-3n2A). Characterized by a distributed antenna system (100).

Since the radio frequency signal is transmitted from the parent device to the child device, a transmission medium between the parent device 200 and the child device is unnecessary, and the installation of the child device can be flexibly dealt with.
Further, the device cost and size of the slave unit can be reduced, and further, complicated digital signal processing is not required and signal delay can be suppressed. Therefore, the introduction and operation costs can be reduced.

  The distributed antenna device (100) according to claim 2 of the present invention, wherein the input / output terminal (201A) is an optical terminal, a coaxial terminal, or a LAN terminal. The antenna device (100).

  As the input / output terminal of the master unit, an optical terminal or a coaxial terminal can be used as in the conventional case, and only by replacing the conventionally installed master unit and slave unit with the master unit and slave unit of the present invention, It becomes possible to introduce a configuration.

  The distributed antenna device (100) according to claim 3 of the present invention is characterized in that the master unit (200) has a multi-element antenna in which a frequency is 3 GHz or more and the number of elements is 16 or more. Alternatively, the distributed antenna device (100) according to any one of (2) and (2).

  Since a plurality of beams can be formed by using a multi-element antenna, it is not necessary to adjust the directions of the master unit and the slave unit, and station placement is possible only by connecting the power supply. Further, since the multi-element antenna uses narrow beams, interference between the beams is suppressed.

The distributed antenna device (100) according to claim 4 of the present invention, wherein the slave unit (310-3n0) is a non-regenerative repeater device. The device (100).

Since the non-regenerative repeater transmits the received signal as it is, there is no limitation on the transmission band like digital transmission using an optical fiber. Further, since the non-reproduction repeater transmits the radio frequency signal as it is, the internal delay is smaller than that of the reproduction repeater. Further, since the non-reproduction repeater does not perform digital signal processing, the device size is small and the cost is low.

  In the distributed antenna device (100) according to claim 5 of the present invention, a plurality of parent device side antennas (206A-206Z) of the slave device or a plurality of the other slave device side antennas (312A-3n2A) are provided. The distributed antenna device 100 according to any one of claims 1 to 4, wherein

By providing a plurality of antennas, it is possible to radiate a beam, that is, transmit and receive, over a wider area than when only one antenna is provided.

It is the whole block diagram. It is a block diagram of a main | base station. It is a block diagram of a child machine. 3 is a configuration diagram in Embodiment 1. FIG. 6 is a configuration diagram in Embodiment 2. FIG. FIG. 7 is a configuration diagram of a third embodiment. FIG. 9 is a configuration diagram in a fourth embodiment. It is a block diagram in Example 5. It is a block diagram in Example 6. FIG. 13 is a configuration diagram of a seventh embodiment. It is a block diagram of a prior art.

  FIG. 1 shows an example of the basic configuration of a distributed antenna device 100 according to the present invention.

The base station device 101 and the master device 200 are connected via a coaxial cable 102 (radio frequency signal). The base station device 101 and the master device 200 may be connected via an optical fiber cable or a LAN cable (digital signal).

The master unit 200 has a master unit side antenna 206A capable of generating n beams and a beam forming unit 205, the beam 1 having a frequency 1 is transmitted from the plurality of slave units 310 to the slave units 3n0, and the beam n is transmitted. Part of the beam n is transmitted to the terminal 400. Although the configuration in which only beam n is transmitted to terminal 400 is illustrated here, other beams n-1, beam n-2, etc. may be configured to be transmitted to terminal 400. Needless to say.

  The cordless handset 310 receives the beam 1 of frequency 1 transmitted from the parent unit 200 by the cordless handset antenna 311A, and directs it to the terminal 400 from the cordless handset antenna 312A other than the cordless handset antenna 311A used for the reception. Transmit beam 1'of frequency 1. Similarly, the other slave units 320 to 3n0 also receive the beam 2 to the beam n of frequency 1 transmitted from the master unit 200 by the slave unit side antenna of each slave unit, and the slave unit side used for the reception. Beams 2 ′ to n ′ of frequency 1 are transmitted from terminal unit side antenna 312A other than antenna 311A toward terminal 400.

In this way, the distributed antenna device 100 transmits radio waves (space) between the devices by using the slave device 310 as a non-reproducing repeater and the slave device 3n0, so that the restriction on the installation of the downstream device is relaxed. Needless to say, radio waves may be transmitted outside the line of sight due to reflection or diffraction.

  Further, since the non-reproducing repeater transmits the received signal as it is, there is no limitation on the transmission band like digital transmission using an optical fiber.

  Further, since the non-reproducing repeater transmits the radio frequency signal as it is, the internal delay is smaller than that of the reproducing repeater. Further, since the non-reproduction repeater does not perform digital signal processing, the device size is small and the cost is low.

  In addition, the antenna used in the conventional non-reproducing repeater that uses an existing frequency such as 3.5 GHz has about 20 elements at most due to the antenna size limitation, but the frequency is, for example, 20 GHz. With this, 400 elements can be used with the same size, so that the directivity of the antenna can be made extremely thin as compared with the half-width, and interference can be suppressed.

  Further, in the future, if the frequency assigned to the mobile communication system becomes a very high frequency such as several tens GHz, a propagation loss increases. To compensate for this, for example, a multi-element antenna having 100 elements or more has been proposed. This multi-element antenna compensates for propagation loss by increasing the number of antenna elements and increasing the antenna gain, and takes advantage of the characteristic that the antenna element size decreases as the frequency increases. Note that as an example, 16 elements at 3.5 GHz, 100 elements at 10 GHz, and 400 elements at 20 GHz can be placed in a 200 mm × 200 mm area. Further, by using the multi-element antennas in a matrix of 20 elements × 20 elements by using, for example, 20 elements each, 20 directivities can be created to form a multi-beam. By using this multi-element antenna in the parent device 200, it becomes possible to direct a plurality of directivities to a plurality of child devices. The beam forming unit 205 can generate a multi-beam by using a Butler matrix, a Rotman lens, an analog phased array, digital beam forming with a baseband signal, or the like.

The characteristics of the above multi-element antenna are (1) the propagation loss can be compensated by the antenna gain, (2) a plurality of directivities can be generated when the antenna is divided and used, and (3) more antenna elements can be used when the frequency becomes higher. Can be placed in the same space, (4) the directivity (half-width) can be reduced as the number of antenna elements increases, and (5) the side lobe can be reduced by setting the excitation amplitude and phase of each element appropriately (side Lobes are the cause of interference, so interference is suppressed) and so on.

  Further, the non-reproducing repeater has the following features (1) small delay, (2) simple and small device configuration, and inexpensive (3) normally installed in an environment with poor signal-to-noise ratio, Since it is used for the purpose of expanding the area by amplifying a signal with an amplifier, it is not effective if the signal deteriorates to some extent. On the other hand, in the present invention, it is possible to suppress the signal deterioration because the signal-to-noise ratio is transmitted between the respective devices (required condition).

  FIG. 2 is a block diagram showing a configuration example of the parent device 200.

The input / output unit 201 has a function of exchanging signals with the base station device 101.
Hereinafter, the direction in which data is transmitted from the network or the like to the child device or the terminal through the parent device is referred to as “downstream”, and the direction in which the data is transmitted from the terminal or child device to the network side through the parent device is referred to as “upstream”.

When the input signal is an RF signal, the master side signal processing unit 202 converts the input signal to an intermediate frequency and then performs analog-digital conversion to perform digital signal processing such as level adjustment and phase adjustment, After performing digital-analog conversion, the result is passed to the frequency conversion unit 203. When the input signal is a digital signal, digital-analog conversion, digital signal processing (level adjustment, phase adjustment, etc.) is performed, digital-analog conversion is performed, and the signal is passed to the frequency conversion unit 203. In the case of “upstream”, in the case of an RF signal, the signal from the frequency conversion unit 203 is subjected to analog-digital conversion, digital signal processing such as level adjustment and phase adjustment is performed, digital-analog conversion is performed, and then input / output is performed. Hand it over to section 201. Further, in the case of a digital signal, the signal from the frequency conversion unit 203 is subjected to analog-digital conversion, digital signal processing such as level adjustment and phase adjustment, digital-analog conversion, and then passed to the input / output unit 201. Then, common to "down" and "up", signal level and quality monitoring, transmission / reception timing detection, delay time detection / delay time correction between the master and slave, and transmission / reception timing control in the slave are performed.

The frequency conversion unit 203 converts the signal from the master unit side signal processing unit 202 into a radio frequency to be used in “downlink”. In the “up”, the signal from the transmission / reception amplification unit 204 is converted into a radio frequency input to the master unit side signal processing unit 202.

The master side transmission / reception amplification unit 204 amplifies the received signal to a predetermined signal level, and also performs synthesis, separation, switching, etc. of transmission / reception signals.
The beam forming unit 205 includes a plurality of beam formers (205A, 205B) and forms a multi-beam.

The base unit side antenna unit 206 transmits a radio wave of a radio frequency in “down”. Also, radio waves of radio frequency are received in "up".

  FIG. 3 is a block diagram showing the configuration of the child device.

The slave side antenna unit a (311) has a function of exchanging signals with the master station device.
The slave side transmission / reception amplification unit 313 amplifies the received signal to a predetermined signal level, and also performs synthesis, separation, switching, etc. of the transmission / reception signal.

The slave unit side antenna unit b (312) has a function of exchanging signals with the terminal 400.
The slave unit side signal processing unit 314 performs signal level and quality monitoring, transmission / reception timing detection, and transmission / reception control at the delay time instructed by the master unit.

The above slave unit side antenna unit a (311), slave unit side antenna unit b (312), slave unit side transmission / reception amplification unit 313, and slave unit side signal processing unit 314 constitute a signal transmission unit 315.

Hereinafter, each embodiment will be described. The same frequency is used unless otherwise specified.

  FIG. 4 is a configuration example in Example 1 which is an embodiment of the present invention. This configuration example is used in an indoor environment, in which a parent device 200 is installed on a back screen in a stadium, and child devices 310 to 340 are arranged on a roof above a stand. The parent device 200 emits beams 1 to 4 from the child device 310 to the child device 340, respectively. The child devices 310 to 340 re-emit the beam toward the audience seats.

  When the space is small like in an office, reflection and diffraction increase, so in a non-reproducing repeater, the transmitted signal may sneak into the other antenna, causing the amplifier to oscillate. For this reason, the non-regenerative repeater must have isolation between the antennas equal to or higher than the amplification degree of the amplifier. This problem can be alleviated because the linearity of the radio wave becomes stronger and the reflection and diffraction decrease as the frequency increases.

FIG. 5 is a configuration example in Example 2 which is an embodiment of the present invention. This configuration example is used in an outdoor environment, and emits a beam from the master unit 200 to the slave unit 340 in the park. The slaves 310 to 340 re-radiate the beam received from the master 200 to the surroundings. It is desirable to be able to see from the parent device 200 to the child device (310-340), but if there is a shield between the parent device 200 and the child device (310-340), the parent device 200 will be the child device (310-340). I can't see through, but sometimes I can connect the line by reflection or diffraction.

FIG. 6 is a configuration example in Example 3 which is an embodiment of the present invention. The present configuration example is different from the second embodiment in that it is used for MIMO. The master device 200 transmits the MIMO-modulated signal 1 to the slave device 320 in the beam 2 and the MIMO-modulated signal 2 to the slave device 340 in the beam 4, and the slave device 320 and the slave device 340 are separated from each other. Emit radio waves toward the same place.

FIG. 7 is a configuration example in Example 4 which is an embodiment of the present invention. This configuration example uses a frequency conversion repeater.

The parent device 200 emits beams 1 to n from the child device 310 to the child device 3n0, respectively. Also, a part of the beam n is radiated toward the terminal 400. The slaves 310 to 3n0 respectively emit the beam 1'to the beam n'of the frequency 2 toward the terminal 400. Although the configuration in which the beam n is radiated toward the terminal 400 is illustrated here, other beams n-1, beam n-2, etc. may be radiated toward the terminal 400. Needless to say.

In this configuration example, since the frequency conversion function is added to the slave unit and each slave unit can convert the signal received from the master unit 200 into the frequency corresponding to each antenna, the antenna used for the slave unit is used. More choices.

  Further, by using the frequency conversion repeater, it is not necessary to make antenna isolation in the slave unit a problem. However, the frequency band needs to be doubled.

FIG. 8 is a configuration example in Example 5 which is an embodiment of the present invention. In this configuration example, some or all of the functions of the base station device 101 are incorporated in the master device 200. Specifically, a part of the physical layer of the eNB is incorporated in the master device 200.

In this configuration example, the higher-level device 500 is connected to the master device 200 via the optical fiber 501 and transmits / receives signals. Then, master device 200 emits beam 1 to beam n of frequency 1 from slave device 310 to slave device 3n0 via antenna 206A on the master device side, and a part of beam n is directed to terminal 400. Radiate. Although the configuration in which the beam n is radiated toward the terminal 400 is illustrated here, other beams n-1, beam n-2, etc. may be radiated toward the terminal 400. Needless to say.

Then, each of the slaves 310 to 3n0 receives the beam 1 to the beam n from the master 200, and re-radiates them as the beam 1'to the beam n'of the frequency 1 toward the terminal 400, respectively.

As a result, the number of devices installed on the base device 200 side can be reduced. Further, the transmission capacity between the upstream device (device located upstream of the base station device 101) and the master device 200 can be significantly reduced.

FIG. 9 is a configuration example in Example 6 which is an embodiment of the present invention. This configuration example is used for a backhaul. That is, the child device becomes the base station device 101, and the parent device 200 becomes the backhaul relay device that transmits between the base station device 101 and the upstream device (network device 600).

Specifically, the master device 200 is connected to the network device 600 as an upstream device via the optical fiber 601 and transmits / receives a signal, while the master device 200 transmits the signal of the frequency 1 via the master device side antenna 206A. The parent device 200 functions as a backhaul relay device by radiating the beams 1 to n from the child device 310 toward the child device 3n0, respectively.

Then, each of the slaves 310 to 3n0 receives the beam 1 to the beam n from the master 200, respectively, and radiates the beams 1 ′ to n ′ of the frequency 1 toward the terminal 400, respectively. It functions as the device 101.

FIG. 10 is a configuration example in Example 7 which is an embodiment of the present invention. In this configuration example, each of the slaves 310 to 3n0 includes a plurality of antennas (311A-311Z to 3n1A-3n1Z, and 312A-312Z to 3n2A-3n2Z).

Specifically, base unit 200 has a plurality of base-side antennas (206A-206Z) capable of generating n beams and beam forming section 205, and beam 1 to frequency n of beam 1 to a plurality of slave units. The data is transmitted from 310 to the child device 3n0.

The slave unit 310 receives the beam 1 of frequency 1 transmitted from the master unit 200 by the plurality of slave unit side antennas (311A-311Z), and other than the plurality of slave unit side antennas (311A-311Z) used for the reception. A beam 1 ′ of frequency 1 is transmitted from the plurality of slave unit side antennas (312A-312Z) to the terminal 400. Similarly, the other slaves 320 to 3n0 also transmit the beam 2 to the beam n of frequency 1 transmitted from the master 200 by a plurality of slave side antennas (31A-321Z to 3n1A-3n1Z) of each slave. Beams 2 ′ to n ′ having a frequency of 1 are transmitted from the plurality of slave side antennas (312A-312Z to 3n2A-3n2Z) other than the slave side antenna used for the reception to the terminal 400.

It is needless to say that the present invention is not limited to the above embodiments and includes various embodiments without departing from the spirit of the present invention.

For example, as a communication system, there are a frequency duplex system and a time division duplex system that uses the same frequency for transmission and reception. However, the distributed antenna device of the mobile communication system according to the present invention is a frequency duplex system. Alternatively, the time division duplex method may be used. In particular, at a frequency of 3 GHz or higher, the time division duplex method may be used.

100 distributed antenna device 101 base station device 102 coaxial cable

200 parent device 201 input / output unit 201A input / output terminal 202 parent device side signal processing unit 203 frequency conversion unit 204 parent device side transmission / reception amplification unit 205 beam forming unit 205A beam forming unit 205B beam forming unit 206 parent unit side antenna unit 206A-Z Base unit antenna

310 cordless handset 1
311 Child device side antenna section a
311A-Z Child device side antenna 312 Child device side antenna part b
312A-Z Handset side antenna 313 Handset side transmission / reception amplification section 314 Handset side signal processing section 315 Signal transmission section 320 Handset 2
321A-Z Child device side antenna 322A-Z Child device side antenna 330 Child device 3
340 cordless handset 4
3n0 cordless handset n
3n1A-Z cordless handset antenna 3n2A-Z cordless handset antenna

400 terminals

500 Upper device 501 Optical fiber

600 network device 601 optical fiber

Claims (5)

A distributed antenna device for a mobile communication system, comprising:
The distributed antenna device,
A base unit having an input / output terminal and a base unit side antenna,
Having a child device having a plurality of child device side antennas,
The base unit side antenna has a beam forming unit having two or more beam forming units,
Child machine, a radio frequency signal received by one of the slave unit side antenna, radio frequency signals from another of the other slave unit antenna and the one of the slave unit side antenna and amplifies it from the base unit have a signal transmitting unit that transmits,
The base unit has a multi-element antenna having a frequency of 3 GHz or more and the number of elements is 16 or more,
The slave is a non-regenerative repeater,
A distributed antenna device , wherein the frequency of the radio frequency signal transmitted by the master unit and the frequency of the radio frequency signal transmitted by the slave unit are the same .   The distributed antenna device according to claim 1, wherein the master unit and the slave unit are installed in an indoor environment.   The distributed antenna device according to claim 1, wherein the slave unit includes a frequency conversion repeater and has a frequency conversion function. 4. The distributed antenna apparatus according to claim 1, wherein the input / output terminal is an optical terminal, a coaxial terminal, or a LAN terminal. One of the slave side antennas for receiving a radio frequency signal from the master unit , or a plurality of other slave side antennas different from the one slave side antenna , characterized in that Item 5. The distributed antenna device according to any one of items 1 to 4.

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