JP2015220524A - Distributed wireless communication base station system and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of wireless signals satisfying the request signal quality, while allowing the frequency and the number of IF bands to be changed.SOLUTION: In a distributed wireless communication base station system where the function of a wireless terminal and a base station transmitting/receiving a wireless signal are divided to a signal processor (BBU) and a wireless device 20(RRH) mounting a plurality of antennas, and the wireless signal is transmitted between a BBU and a RRH by analog RoF transmission system by connecting the BBU and RRH by means of an optical fiber, an A/D conversion unit is provided at the pre-stage of a frequency conversion unit of IF band and BB band in the BBU and a signal extraction unit of IF band, A/D conversion units 41, 43 are provided at the pre-stage of frequency conversion units 23, 28 of IF band and BB band in the RRH and a signal extraction unit 22 of IF band, frequency conversion and signal extraction are performed digitally, and then the digital signal is returned back to an analog signal and converted into an optical signal or a RF signal.

Description

  In the present invention, the function of a base station for transmitting and receiving radio signals to and from a radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and BBU and RRH. Are connected by an optical fiber, and a wireless signal is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method, a BBU or RRH communication method, and a BBU or RRH communication method. It relates to a communication program.

  In the cellular system, in order to improve the degree of freedom of the cell configuration, the base station function is divided physically into a signal processing unit (BBU: Base Band Unit) and an RF unit (RRH: Remote Radio Unit), and physically separated It is considered to do. The BBU and RRH are connected by a coaxial cable, an optical fiber, or the like. In particular, the transmission distance can be increased by connecting by an optical fiber. At this time, the radio signal is transmitted between the BBU and RRH by the RoF technology. RoF technology can be broadly classified into analog RoF technology and digital RoF technology according to the optical transmission method. The digital RoF technology can transmit a radio signal with almost no distortion, but requires a very wide band in the optical fiber section. On the other hand, in the analog RoF technology, the radio signal is distorted as compared with the digital RoF transmission, but the required bandwidth in the optical fiber section is almost equal to the used frequency bandwidth of the radio signal. Therefore, the analog RoF technology can save the required bandwidth between BBU and RRH.

  Each RRH may be equipped with a plurality of antennas for MIMO (multiple-input and multiple-output) transmission. In spatial multiplexing transmission in MIMO, a radio signal having different information is transmitted from each antenna on the transmission side, and a signal processing is performed on the reception signal of each antenna on the reception side to separate and receive a plurality of pieces of information. improves. For example, LTE (Long Term Evolution) supports a maximum of 4 multiplexing in the downlink, and LTE-Advanced supports a maximum of 8 multiplexing in the downlink. Although each of these radio signals can be transmitted by being divided into different wavelengths as in Patent Document 1, if these radio signals are frequency-converted to different IF bands, a plurality of radio signals can be transmitted with one wavelength and one fiber. Simultaneous transmission is possible, and this is considered more economical.

  FIG. 1 shows a device configuration example of a related art BBU. Since the BBU 10 is downlink communication, the modulation / demodulation unit 11 that outputs a digital bit sequence of a radio modulation signal for each antenna #i, and the D / A conversion unit 12 that converts each digital signal output from the modulation / demodulation unit 11 into an analog signal. And a frequency converter (BB → IF # i) 13 for up-converting each analog signal from the baseband to the IF band, an adder 19 for adding them, and an analog electric signal converted into an optical signal for RRH side E / O converter 14 for transmitting to Further, the BBU 10 is for uplink communication, and an O / E conversion unit 15 that converts an optical signal into an electrical signal, a signal extraction unit (IF # i) 16 that extracts a signal of each IF band from an analog electrical signal, A frequency conversion unit (IF # i → BB) 17 that down-converts an IF band signal into a baseband band, and an A / D conversion unit 18 that converts each down-converted analog signal into a digital signal. It is also possible to multiplex downlink signals and uplink signals with different wavelengths. In this case, a filter that separates the upstream signal and the downstream signal is required. The signal extraction unit is configured by a BPF (Band Pass Filter).

  FIG. 2 shows an example of the configuration of a related RRH apparatus. Since the RRH 20 is downlink communication, the O / E conversion unit 21 that converts the optical signal received from the BBU into an electrical signal, and the signal extraction unit (IF # i) 22 that extracts a signal of each IF band from the analog electrical signal. A frequency conversion unit (IF # i → RF) 23 for up-converting signals in each IF band to an RF band, an amplifier 24 for amplifying the power to a set transmission power, a transmission / reception switching unit 25, and an antenna 26. . Further, the RRH 20 is an uplink communication, and therefore, for an uplink communication, an antenna 26 that transmits / receives a radio signal, a transmission / reception switching unit 25 that switches transmission / reception, and an amplifier 27 that amplifies the signal power of the received radio signal to a level at which signal processing is possible. A frequency converter (RF → IF # i) 28 for down-converting the RF signal of each antenna 26 to a different IF band, an adder 30 for adding each signal down-converted to a different IF band, It has an E / O converter 29 that converts an analog signal to be output into an optical signal and transmits it. The transmission / reception switching unit is compatible with both FDD (Frequency Division Duplex) and TDD (Time Division Duplex).

JP 2011-199369 A

  FIG. 3 shows an example of operation during downlink communication according to the related art. In related-art analog RoF transmission, the O / E converter, the D / A converter, and the like have frequency characteristics, and the higher the frequency, the lower the output power. At this time, the signal quality of the radio signal transmitted at the high IF frequency is deteriorated as compared with the signal transmitted at the low IF frequency. For this reason, there is a possibility that a part of the radio signal transmitted by analog RoF does not satisfy the required signal quality.

  Each IF frequency can be lowered by narrowing the interval of the frequency arrangement of each radio signal. However, when the interval between radio signals is narrowed on the IF band, a filtering process with a narrower transition band width is required in the signal extraction unit on the receiving side. The reduction of the transition bandwidth leads to an increase in the cost of the analog device, and the transition bandwidth that can be reduced is also limited by the performance of the analog device.

  In addition, when the frequency conversion is realized by an analog device as in the related art, it is difficult to change the frequency and number of IF bands to be used. For this reason, it is difficult to flexibly change the IF frequency according to the actual value of the transition bandwidth of the signal extraction unit, or to temporarily increase the number of IF frequencies and send a monitoring signal or a control signal. .

  In order to solve the above-described problems, an object of the present invention is to increase the number of radio signals that satisfy the required signal quality and to change the frequency and number of IF bands to be used.

  The present invention digitally performs frequency conversion between IF band and BB band in BBU, frequency conversion between IF band and RF band in RRH, and IF band signal extraction in BBU and RRH.

Specifically, the distributed radio communication base station system according to the present invention is:
The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are A distributed radio communication base station system that connects the BBU and the RRH by connecting with an optical fiber and transmitting the radio signal in an analog RoF (Radio over Fiber) transmission system,
The BBU is
An IF converter that converts the frequency of the digital electric signal to be transmitted to the RRH into a different IF (Intermediate Frequency) band for each radio signal;
An analog converter that converts each signal from the IF converter into an analog value;
An optical conversion unit that converts an electrical signal from the analog conversion unit into an optical signal and transmits the optical signal to the RRH, and
The RRH is
An electrical converter for converting an optical signal from the BBU into an electrical signal;
A digital converter that converts a signal from the electrical converter into a digital value;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band;
An RF converter that converts the frequency of each IF band separated by the signal extraction unit into an RF (Radio Frequency) band corresponding to the plurality of antennas;
An analog conversion unit that converts a signal from the RF conversion unit into an analog value and outputs the analog value to the antenna.

Specifically, the distributed radio communication base station system according to the present invention is:
The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are A distributed radio communication base station system that connects the BBU and the RRH by connecting with an optical fiber and transmitting the radio signal in an analog RoF (Radio over Fiber) transmission system,
The BBU is
An IF converter that converts the frequency of the digital electrical signal to be transmitted to the RRH into a different IF band for each radio signal;
An analog converter that converts each signal from the IF converter into an analog value;
An optical conversion unit that converts an electrical signal from the analog conversion unit into an optical signal and transmits the optical signal to the RRH, and
The RRH is
An electrical converter for converting an optical signal from the BBU into an electrical signal;
A digital converter that converts a signal from the electrical converter into a digital value;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band;
A specific frequency converter that converts the frequency of each IF band separated by the signal extraction unit into a predetermined IF band;
An analog conversion unit that converts an output signal of the specific frequency conversion unit into an analog value;
And an RF converter that changes the frequency of an output signal from the analog converter to an RF band corresponding to the plurality of antennas.

  In the distributed radio communication base station system according to the present invention, the BBU is configured to set the signal power to be transmitted to the RRH to a high or low frequency in each IF band for frequency conversion of the IF converter before the IF converter. You may further provide the electric power adjustment part adjusted according to it.

In the distributed radio communication base station system according to the present invention,
The RRH is
A control signal for generating a control signal for adjusting the signal power of each IF band in the power adjustment unit based on the power value or EVM (Error Vector Magnitude) value of each IF band signal separated by the signal extraction unit The creation department;
A control IF converter that converts the control signal generated by the control signal generator into an IF band for control signal transmission;
An analog converter that converts the output signal of the control IF converter from a digital value to an analog value;
An optical converter that converts an electrical signal from the analog converter into an optical signal and transmits the optical signal to the BBU;
Further comprising
The BBU is
An electrical converter that converts an optical signal from the RRH into an electrical signal;
A digital converter that converts a signal from the electrical converter into a digital value;
A control signal extractor for separating the IF band for transmitting the control signal from the output signal of the digital converter;
A control BB converter that converts the IF band for transmission of the control signal separated by the control signal extractor to a BB (baseband) band;
With
The power adjustment unit in the BBU adjusts the signal power of each IF band according to a control signal from the control BB conversion unit.

Specifically, the distributed radio communication base station system according to the present invention is:
The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A distributed radio communication base station system that connects the BBU and the RRH by connecting with an optical fiber and transmitting the radio signal in an analog RoF (Radio over Fiber) transmission system,
The RRH is
A digital converter that converts each of the radio signals received by the antenna into a digital value;
An IF converter that converts the frequency of the signal from the digital converter to a different IF band for each wireless signal;
An analog converter that converts each signal from the IF converter into an analog value;
An optical conversion unit that converts an electrical signal from the analog conversion unit into an optical signal and transmits the optical signal to the BBU, and
The BBU is
An electrical converter that converts an optical signal from the RRH into an electrical signal;
A digital converter that converts a signal from the electrical converter into a digital value;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band;
A BB conversion unit that converts each IF band separated by the signal extraction unit into a BB (baseband) band;
And a demodulator that demodulates each radio signal received by the antenna using a digital signal from the BB converter.

Specifically, the distributed radio communication base station system according to the present invention is:
The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A distributed radio communication base station system that connects the BBU and the RRH by connecting with an optical fiber and transmitting the radio signal in an analog RoF (Radio over Fiber) transmission system,
The RRH is
A specific frequency converter that converts the frequency of a radio signal received by the antenna to a predetermined IF band;
A digital converter that converts an output signal from the specific frequency converter into a digital value;
An IF converter that converts the frequency of the signal from the digital converter to a different IF band for each wireless signal;
An analog converter that converts each signal from the IF converter into an analog value;
An optical conversion unit that converts an electrical signal from the analog conversion unit into an optical signal and transmits the optical signal to the BBU, and
The BBU is
An electrical converter that converts an optical signal from the RRH into an electrical signal;
A digital converter that converts a signal from the electrical converter into a digital value;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band;
A BB converter that converts the frequency of each IF band separated by the signal extractor into a BB band;
And a demodulator that demodulates each radio signal received by the antenna using a digital signal from the BB converter.

  In the distributed radio communication base station system according to the present invention, the RRH is configured so that each IF band for converting the signal power to be transmitted to the BBU between the digital conversion unit and the IF conversion unit is frequency-converted by the IF conversion unit. An electric power adjustment unit that adjusts the frequency according to the frequency level may be further provided.

In the distributed radio communication base station system according to the present invention,
The BBU is
A control signal generating unit that generates a control signal for adjusting the signal power of each IF band in the power adjustment unit based on the power value or EVM value of each IF band signal separated by the signal extraction unit;
A control IF converter that converts the control signal generated by the control signal generator into an IF band for control signal transmission;
An analog converter that converts the output signal of the control IF converter from a digital value to an analog value;
An optical conversion unit that converts an electrical signal from the analog conversion unit into an optical signal and transmits the optical signal to the RRH;
Further comprising
The RRH is
An electrical converter for converting an optical signal from the BBU into an electrical signal;
A digital converter that converts a signal from the electrical converter into a digital value;
A control signal extractor for separating the IF band for transmitting the control signal from the output signal of the digital converter;
A control BB converter that converts the frequency of the IF band for transmission of the control signal separated by the control signal extractor into a BB band;
With
The power adjustment unit in the RRH adjusts the signal power of each IF band according to a control signal from the control BB conversion unit.

Specifically, the communication method of BBU in the distributed radio communication base station system according to the present invention is:
The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are A communication method of the BBU in a distributed wireless communication base station system in which the wireless signal is connected by an optical fiber and is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method,
An IF conversion procedure in which the IF conversion unit converts the frequency of the digital electric signal transmitted to the RRH into a different IF (Intermediate Frequency) band for each radio signal;
An analog conversion unit converts each signal from the IF conversion unit into an analog value, and an analog conversion procedure;
In order,
The electrical signal from the analog converter is converted into an optical signal and transmitted to the RRH.

Specifically, the communication method of RRH in the distributed radio communication base station system according to the present invention is:
The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are A communication method of the RRH in a distributed radio communication base station system in which the radio signal is connected by an optical fiber and is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method,
A digital conversion procedure in which a digital conversion unit converts an analog signal obtained by converting an optical signal from the BBU into an electrical signal into a digital value;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band; and
An RF conversion procedure in which an RF conversion unit frequency-converts each IF band separated by the signal extraction unit into an RF band according to the plurality of antennas;
An analog conversion unit that converts a signal from the RF conversion unit into an analog value and outputs the analog value to the antenna;
Have

Specifically, the communication method of RRH in the distributed radio communication base station system according to the present invention is:
The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A communication method of the RRH in a distributed radio communication base station system in which the radio signal is connected by an optical fiber and is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method,
A digital conversion procedure in which a digital conversion unit converts an analog signal obtained by converting an optical signal from the BBU into an electrical signal into a digital value;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band; and
A specific frequency conversion unit, a down-conversion procedure for frequency-converting each IF band separated by the signal extraction unit to a predetermined IF band;
An analog conversion unit converts an output signal of the specific frequency conversion unit into an analog value; and
An RF conversion procedure in which the RF conversion unit changes the frequency of the output signal from the analog conversion unit to an RF band corresponding to the plurality of antennas;
Have

Specifically, the communication method of BBU in the distributed radio communication base station system according to the present invention is:
The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A communication method of the BBU in a distributed wireless communication base station system in which the wireless signal is connected by an optical fiber and is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method,
A digital conversion procedure in which a digital conversion unit converts a signal obtained by converting an optical signal from the RRH into an electric signal;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band; and
A BB conversion procedure in which a BB conversion unit converts each IF band separated by the signal extraction unit into a BB (baseband) band;
In order,
A demodulator demodulates each radio signal received by the antenna using the digital signal from the BB converter.

Specifically, the communication method of RRH in the distributed radio communication base station system according to the present invention is:
The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are A communication method of the RRH in a distributed radio communication base station system in which the radio signal is connected by an optical fiber and is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method,
A digital conversion procedure for converting each of the radio signals received by the antenna into a digital value;
IF conversion unit, frequency conversion of the signal from the digital conversion unit to different IF band for each wireless signal,
An analog conversion unit converts each signal from the IF conversion unit into an analog value, and an analog conversion procedure;
In order,
The electrical signal from the analog conversion unit is converted into an optical signal and transmitted to the BBU.

Specifically, the communication method of RRH in the distributed radio communication base station system according to the present invention is:
The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A communication method of the RRH in a distributed radio communication base station system in which the radio signal is connected by an optical fiber and is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method,
A down-conversion procedure in which the specific frequency conversion unit converts the frequency of the radio signal received by the antenna into a predetermined IF band;
A digital conversion procedure in which the digital conversion unit converts the output signal from the specific frequency conversion unit into a digital value;
IF conversion unit, frequency conversion of the signal from the digital conversion unit to different IF band for each wireless signal,
An analog conversion unit converts each signal from the IF conversion unit into an analog value, and an analog conversion procedure;
In order,
The electrical signal from the analog conversion unit is converted into an optical signal and transmitted to the BBU.

  Specifically, the BBU communication program in the distributed radio communication base station system according to the present invention is a program for causing a computer to execute each procedure in the BBU communication method according to the present invention.

  Specifically, the RRH communication program in the distributed radio communication base station system according to the present invention is a program for causing a computer to execute each procedure in the RRH communication method according to the present invention.

  The above inventions can be combined as much as possible.

  According to the present invention, the number of radio signals that satisfy the required signal quality can be increased. At that time, the frequency and number of IF bands to be used can be changed.

The apparatus structural example of BBU of related technology is shown. The apparatus structural example of RRH of related technology is shown. It is an example of the signal in the downlink of related technology, (a) shows the signal power of each IF band at the time of transmission from BBU, (b) shows the signal power of each IF band at the time of reception by RRH, (C) shows EVM after A / D conversion by RRH. An operation example during downlink communication is shown. The apparatus structural example of BBU which concerns on Embodiment 1-1 is shown. The apparatus structural example of RRH which concerns on Embodiment 1-1 is shown. 1 shows an example of a downlink distributed wireless communication base station communication method according to Embodiment 1-1. 1 shows an example of an uplink distributed wireless communication base station communication method according to Embodiment 1-1. The apparatus structural example of RRH which concerns on Embodiment 1-2 is shown. An example of the downlink distributed radio | wireless communication base station communication method which concerns on Embodiment 1-2 is shown. 7 shows an example of an uplink distributed wireless communication base station communication method according to Embodiment 1-2. The apparatus structural example of BBU10 which concerns on Embodiment 2-1 is shown. 7 shows an example of a downlink distributed radio communication base station communication method according to Embodiment 2-1. The apparatus structural example of the electric power adjustment part 31 according to radio | wireless signal is shown. 7 is an example of a downlink signal according to Embodiment 2-1, in which (a) illustrates signal power of each IF band input to the D / A conversion unit 12 of the BBU 10, and (b) illustrates A / D conversion of the RRH 20; The signal power of each IF band output from the unit 41 is shown, and (c) shows the EVM of the signal of each IF band output from the A / D conversion unit 41 of the RRH 20. The apparatus structural example of RRH20 which concerns on Embodiment 2-2 is shown. An example of the uplink distributed radio | wireless communication base station communication method which concerns on Embodiment 2-2 is shown. The apparatus structural example of BBU10 which concerns on Embodiment 2-3 is shown. The apparatus structural example of RRH20 which concerns on Embodiment 2-3 is shown. An example of the downlink distributed radio | wireless communication base station communication method which concerns on Embodiment 2-3 is shown. An example of the uplink distributed radio | wireless communication base station communication method which concerns on Embodiment 2-3 is shown.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to embodiment shown below. These embodiments are merely examples, and the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art. In the present specification and drawings, the same reference numerals denote the same components.

  In the distributed radio communication base station system according to the present embodiment, the function of a base station for transmitting and receiving radio signals to and from a radio terminal is a radio apparatus (RRH: Remote Radio) equipped with a signal processing device (BBU: Base Band Unit) and a plurality of antennas. Head) and BBU and RRH are connected by an optical fiber, and a radio signal is transmitted between BBU and RRH by an analog RoF (Radio over Fiber) transmission method. In the present invention, the problems of the related art are solved by the following two points using DSP (Digital Signal Processing) in this system.

(I) In BBU or RRH, frequency conversion and signal extraction are performed digitally (see Embodiment 1-1 and Embodiment 1-2). The IF frequency can be easily changed by digitally converting the frequency to the IF band. Also, by performing signal extraction digitally, a narrow transition bandwidth can be realized without being restricted by analog devices. As a result, the interval between the radio signals can be narrowed, a low IF frequency can be used, and a decrease in signal power of each radio signal is suppressed, and the number of radio signals satisfying the required signal quality increases.

(Ii) On the transmission side, power adjustment is performed for each radio signal (see Embodiments 2-1 to 2-3). The radio signal power in the IF band that is estimated to have low signal quality is increased, and the radio signal power in the IF band that is estimated to have high signal quality is reduced within a range that satisfies the required signal quality. This increases the number of radio signals that satisfy the required signal quality. Since the power adjustment can be realized by multiplying each wireless signal by a real value, it is sufficient if there is a 1-tap multiplier corresponding to the number of wireless signals.

(Embodiment 1-1)
In this embodiment, frequency conversion and signal extraction are performed digitally in downlink / uplink communication. FIG. 4 shows a device configuration example of the BBU according to this embodiment, and FIG. 5 shows a device configuration example of the RRH according to this embodiment.

  The BBU 10 according to the present embodiment, for downlink communication, improves the modulation / demodulation unit 11 that outputs a digital bit sequence of a radio modulation signal for each antenna #i, and upgrades each signal output by the modulation / demodulation unit from the baseband to the IF band. Frequency converter (BB → IF # i) 13 for conversion, adder 19 for adding them, D / A converter 12 for converting the added signal into an analog signal, and converting an analog electric signal into an optical signal And an E / O converter 14 for transmitting to the RRH side. In this embodiment, although the example provided with the separate frequency conversion part 13 for every antenna 26 was shown, this invention is not limited to this. For example, the frequency conversion unit 13 may be configured to separately perform frequency conversion on a plurality of input wireless signals, and output the signals separately or add and output them. Thereby, the number of the frequency conversion parts 13 can be reduced.

  Further, the BBU 10 of the present embodiment includes an O / E conversion unit 15 that converts an optical signal into an electrical signal for uplink communication, an A / D conversion unit 18 that digitizes an analog signal converted into an electrical signal, It has a signal extraction unit (IF # i) 16 that extracts each IF band signal from the digital bit sequence, and a frequency conversion unit (IF # i → BB) 17 that downconverts each IF band signal to a baseband band. In this embodiment, although the example provided with the separate signal extraction part 16 and the frequency conversion part 17 for every antenna 26 was shown, this invention is not limited to this. For example, the signal extraction unit 16 and the frequency conversion unit 17 may be configured to separately perform signal extraction and frequency conversion on a plurality of input wireless signals and output them separately. As a result, the number of signal extraction units 16 and frequency conversion units 17 can be reduced.

  The RRH 20 of the present embodiment includes an O / E conversion unit 21 that converts an optical signal received from the BBU 10 into an electrical signal, an A / D conversion unit 41 that converts an analog signal into a digital signal, and digital communication for downlink communication. A signal extraction unit (IF # i) 22 that extracts signals of each IF band from the signal, a frequency conversion unit (IF # i → RF) 23 that upconverts the signals of each IF band to an RF band, and the up-conversion It includes a D / A converter 42 that converts each signal into an analog signal, an amplifier 24 that amplifies the power to a set transmission power, a transmission / reception switching unit 25, and an antenna 26. In this embodiment, although the example provided with the separate signal extraction part 22, the frequency conversion part 23, the D / A conversion part 42, the amplifier 24, and the transmission / reception switching part 25 for every antenna 26 was shown, this invention is not limited to this. . For example, the signal extraction unit 22, the frequency conversion unit 23, the D / A conversion unit 42, the amplifier 24, and the transmission / reception switching unit 25 separately perform signal extraction / frequency conversion / D / A conversion on a plurality of input radio signals. -Amplification / transmission / reception switching may be performed and output separately. Thereby, the number of the signal extraction part 22, the frequency conversion part 23, the D / A conversion part 42, the amplifier 24, and the transmission / reception switching part 25 can be reduced.

  Further, the RRH 20 of the present embodiment is a level at which signal processing can be performed on the signal power of the received radio signal, the antenna 26 that transmits / receives the radio signal, the transmission / reception switching unit 25 that switches between transmission / reception, for uplink communication. An amplifier 27 for amplifying the signal, an A / D converter 43 for converting the amplified analog signal into a digital signal, and a frequency converter (RF → IF # i) 28 for downconverting the RF signal of each antenna to a different IF band. An adder 30 that adds the signals down-converted to different IF bands, a D / A converter 44 that converts a digital signal output from the adder 30 into an analog signal, and an output of the D / A converter 44 An E / O converter 29 for converting the analog signal to be converted into an optical signal and transmitting the optical signal. In this embodiment, although the example provided with the separate transmission / reception switching part 25, the amplifier 27, the A / D conversion part 43, and the frequency conversion part 28 for every antenna 26 was shown, this invention is not limited to this. For example, the transmission / reception switching unit 25, the amplifier 27, the A / D conversion unit 43, and the frequency conversion unit 28 perform transmission / reception switching / amplification / A / D conversion / frequency conversion separately on a plurality of input radio signals, It may be configured to output separately. As a result, the number of transmission / reception switching units 25, amplifiers 27, A / D conversion units 43, and frequency conversion units 28 can be reduced.

  FIG. 6 shows an example of a downlink distributed wireless communication base station communication method according to this embodiment. The downlink distributed wireless communication base station communication method according to the present embodiment includes an IF conversion procedure (S101), an analog conversion procedure (S103), an optical conversion procedure (S104), an electrical conversion procedure (S105), A digital conversion procedure (S106), a signal extraction procedure (S107), an RF conversion procedure (S108), and an analog conversion procedure (S109) are sequentially provided.

During downlink communication, the BBU 10 executes an IF conversion procedure (S101) to an optical conversion procedure (S104).
In the IF conversion procedure (S101), the frequency converter (BB → IF # i) 13 upconverts each signal modulated by the modem 11 from the baseband to the IF band. The adder 19 adds the signals output from the frequency converters 13 (S102).
In the analog conversion procedure (S103), the D / A converter 12 converts the signal added by the adder 19 into an analog signal.
In the optical conversion procedure (S104), the E / O conversion unit 14 converts the analog electrical signal from the D / A conversion unit 12 into an optical signal and transmits it to the RRH 20 side.

During downlink communication, the RRH 20 executes an electrical conversion procedure (S105) to an analog conversion procedure (S109).
In the electrical conversion procedure (S105), the O / E converter 21 converts the optical signal received from the BBU 10 into an electrical signal.
In the digital conversion procedure (S106), the A / D conversion unit 41 converts an analog signal into a digital signal.
In the signal extraction procedure (S107), the signal extraction unit 22 extracts each IF band signal from the digital signal.
In the RF conversion procedure (S108), the frequency conversion unit 23 up-converts each IF band signal to the RF band.
In the analog conversion procedure (S109), the D / A converter 42 converts each signal up-converted by the frequency converter 23 into an analog signal. As a result, an RF signal is transmitted from the antenna 26.

  FIG. 7 shows an example of an uplink distributed wireless communication base station communication method according to the present embodiment. The uplink distributed wireless communication base station communication method according to the present embodiment includes a digital conversion procedure (S201), an IF conversion procedure (S202), an analog conversion procedure (S204), an optical conversion procedure (S205), An electric conversion procedure (S206), a digital conversion procedure (S207), a signal extraction procedure (S208), and a BB conversion procedure (S209) are sequentially provided.

During uplink communication, the RRH 20 executes a digital conversion procedure (S201) to an optical conversion procedure (S205).
In the digital conversion procedure (S201), the A / D conversion unit 43 converts the analog signal amplified by the amplifier 27 into a digital signal.
In the IF conversion procedure (S202), the frequency conversion unit 28 down-converts the RF signal of each antenna 26 to a different IF band. The adder 30 adds the signals down-converted by the frequency converters 28.
In the analog conversion procedure (S204), the D / A converter 44 converts the digital signal output from the adder 30 into an analog signal.
In the optical conversion procedure (S205), the E / O conversion unit 29 converts the analog signal output from the D / A conversion unit 44 into an optical signal and transmits it to the BBU 10.

During uplink communication, the BBU 10 executes an electrical conversion procedure (S206) to a BB conversion procedure (S209).
In the electrical conversion procedure (S206), the O / E conversion unit 15 converts the optical signal from the RRH 20 into an electrical signal.
In the digital conversion procedure (S207), the A / D conversion unit 18 digitizes the analog signal converted into the electrical signal.
In the signal extraction procedure (S208), the signal extraction unit 16 extracts each IF band signal from the digital bit sequence.
In the BB conversion procedure (S209), the frequency conversion unit 17 down-converts each IF band signal from the signal extraction unit 16 to the base band. Thereafter, the modem unit 11 demodulates the signal received by each antenna 26.

  As described above, the RRH 20 according to the present embodiment includes the signal extraction unit in the previous stage of the signal extraction unit 22, the D / A conversion unit 42 in the subsequent stage of the frequency conversion unit 23, and the previous stage of the frequency conversion unit 28. An A / D converter 43 is provided, and a D / A converter 44 is provided downstream of the frequency converter 28. In the related art, up / down conversion and signal extraction are realized on analog, but in Embodiment 1-1, they are realized on digital. For this reason, in the system according to the present embodiment, it is easy to change the IF frequency in the frequency conversion units 23 and 28 as compared with the related art. Moreover, the transition bandwidth of the filtering process in the signal extraction unit 22 can also be reduced without being restricted by the analog device. Therefore, the system according to the present embodiment can use a low IF band with relatively small signal power attenuation, and can increase the number of radio signals that satisfy the required signal quality.

  The BBU 10 may be realized by causing a computer to function as the modem unit 11, the frequency conversion units 13 and 17, the adder 19, the signal extraction unit 16, the D / A conversion unit 12, and the A / D conversion unit 18. Good. In this case, each configuration is realized by a CPU (Central Processing Unit) in the BBU 10 executing a computer program stored in a storage unit (not shown). The RRH 20 may be realized by causing a computer to function as the signal extraction unit 22, the frequency conversion units 23 and 28, the adder 30, the A / D conversion units 41 and 43, and the D / A conversion units 42 and 44. In this case, each configuration is realized by the CPU in the RRH 20 executing a computer program stored in a storage unit (not shown).

(Embodiment 1-2)
In the embodiment 1-1, frequency conversion from IF to RF and frequency conversion from RF to IF are performed digitally in downlink / uplink communication. In the embodiment 1-2, frequency conversion from IF to RF and frequency conversion from RF to IF are performed on analog. Thereby, the sampling frequency calculated | required by the A / D conversion part is reduced.

  An example of the apparatus configuration of the BBU 10 when the embodiment 1-2 is applied is the same as that when the embodiment 1-1 is applied. FIG. 8 shows a device configuration example of the RRH 20 according to the present embodiment.

  The RRH 20 of the present embodiment replaces the frequency converter 23 of the embodiment 1-1 with a frequency converter (IF # i → IF # a) (i = 1, 2, 3,... N) 51 in downlink communication. And a frequency converter (IF # a → RF) 52.

  Further, the RRH 20 of the present embodiment replaces the frequency converter 28 in the uplink communication with a frequency converter (RF → IF # a) 53 and a frequency converter (IF # a → IF # i) (i = 1). , 2, 3... N) 54.

  FIG. 9 shows an example of a downlink distributed wireless communication base station communication method according to this embodiment. The downlink distributed wireless communication base station communication method according to the present embodiment includes an IF conversion procedure (S101), an analog conversion procedure (S103), an optical conversion procedure (S104), an electrical conversion procedure (S105), A digital conversion procedure (S106), a signal extraction procedure (S107), a down-conversion procedure (S111), an analog conversion procedure (S109), and an RF conversion procedure (S108) are sequentially provided.

  During downlink communication, the BBU 10 executes an IF conversion procedure (S101) to an optical conversion procedure (S104). The IF conversion procedure (S101) to the optical conversion procedure (S104) are as described in the embodiment 1-1.

  During downlink communication, the RRH 20 executes an electrical conversion procedure (S105) to an RF conversion procedure (S108). In this embodiment, a down-conversion procedure (S111) is further provided after the signal extraction procedure (S107), and an RF conversion procedure (S108) is performed after the analog conversion procedure (S109).

  In the down-conversion procedure (S111), the frequency converting unit 51 converts the IF frequencies (IF # 1 to N) of the signal extracted by the signal extracting unit 22 into a common IF frequency (IF # a).

In the analog conversion procedure (S109), the D / A converter 42 converts each signal down-converted by the frequency converter 51 into an analog signal.
In the RF conversion procedure (S108), the frequency converter 52 up-converts each analog signal frequency-converted to the IF frequency (IF # a) to the RF band.
As a result, an RF signal is transmitted from the antenna 26.

  FIG. 10 shows an example of the uplink distributed wireless communication base station communication method according to the present embodiment. The downlink distributed wireless communication base station communication method according to the present embodiment includes a down-conversion procedure (S211), a digital conversion procedure (S201), an IF conversion procedure (S202), an analog conversion procedure (S204), An optical conversion procedure (S205), an electrical conversion procedure (S206), a digital conversion procedure (S207), a signal extraction procedure (S208), and a BB conversion procedure (S209) are sequentially provided.

  During uplink communication, the RRH 20 performs a down-conversion procedure (S211) to an optical conversion procedure (S205). In the present embodiment, a down-conversion procedure (S211) is further included before the digital conversion procedure (S201).

In the down-conversion procedure (S211), the frequency converter 53 converts the RF band analog signal received by each antenna 26 to a common IF frequency (IF # a).
In the digital conversion procedure (S201), the A / D conversion unit 43 converts the analog signal down-converted by the frequency conversion unit 53 into a digital signal.
In the IF conversion procedure (S202), the frequency converter 54 converts the IF frequency (IF # a) of the signal digitized by the A / D converter 43 into different IF frequencies (IF # 1 to N). The adder 30 adds the signals down-converted by the frequency converters 28.
The analog conversion procedure (S204) to BB conversion procedure (S209) are as described in the embodiment 1-1.

  Here, the frequency IF # a converted by the frequency converters 51 and 53 in the down-conversion procedures S111 and S211 is a frequency lower than RF. For this reason, in Embodiment 1-2, the frequency lower than RF is handled digitally, and the sampling frequency calculated | required by the A / D conversion parts 42 and 43 is reduced compared with Embodiment 1-1.

  The BBU 10 may be realized by causing a computer to function as the modem unit 11, the frequency conversion units 13 and 17, the adder 19, the signal extraction unit 16, the D / A conversion unit 12, and the A / D conversion unit 18. Good. In this case, each configuration is realized by a CPU (Central Processing Unit) in the BBU 10 executing a computer program stored in a storage unit (not shown). The RRH 20 is realized by causing the computer to function as the signal extraction unit 22, the frequency conversion units 51, 52, 53, 54, the adder 30, the A / D conversion units 41, 43, and the D / A conversion units 42, 44. May be. In this case, each configuration is realized by the CPU in the RRH 20 executing a computer program stored in a storage unit (not shown).

(Embodiment 2-1)
In Embodiment 2-1, power adjustment is performed on the BBU 10 side during downlink communication. The apparatus configuration of the RRH 20 when the embodiment 2-1 is applied is the same as that of the embodiment 1-1.

  FIG. 11 shows a device configuration example of the BBU 10 according to the embodiment 2-1. Unlike the embodiment 1-1, the BBU 10 of the present embodiment includes a power adjustment unit 31 for each radio signal.

  FIG. 12 shows an example of a downlink distributed wireless communication base station communication method according to this embodiment. The downlink distributed wireless communication base station communication method according to the present embodiment further includes a power adjustment procedure (S113) before the IF conversion procedure (S101) described in the embodiment 1-1.

  In the power adjustment procedure (S113), the radio signal-specific power adjustment unit 31 performs power adjustment on the signal for each antenna #i output from the modem unit 11. The power value to be adjusted is determined according to the frequency characteristics of devices such as the D / A converter 12 and the O / E converter 41.

  A device configuration example of the radio signal-specific power adjustment unit 31 is shown in FIG. 13. The radio signal power adjustment unit 31 includes an adjustment power determination unit 311 and a 1-tap multiplier 312 that multiplies each radio signal by a coefficient. The frequency characteristics of devices such as the D / A conversion unit 12 and the O / E conversion unit 41 are measured in advance, and are input to the adjustment power determination unit 311. The adjusted power determination unit 311 calculates and outputs a coefficient so that the power of each radio signal after A / D conversion in the A / D conversion unit 41 on the reception side is aligned. The input to the adjusted power determination unit 311 is performed before the operation is started.

  FIG. 14 shows an example of signals in the BBU 10 and the RRH 20. As shown in FIG. 14A, the signal whose power is adjusted by the radio signal-specific power adjustment unit 311 is output from the radio signal-specific power adjustment unit 31. At this time, the power is adjusted according to the frequency. For example, high frequency signals increase power, and low frequency signals decrease power. Thus, the power-adjusted signal is analog RoF transmitted from the BBU 10 to the RRH 20. When these radio signals are observed at the time when they are output by the A / D converter 41 of the RRH 20, as shown in FIG. Even if the signal quality of some radio signals does not satisfy the required value as shown in FIG. 3, all the radio signals in FIG. 14 satisfy the required signal quality.

  The embodiment 2-1 is applicable not only to the embodiment 1-1 but also to the embodiment 1-2.

  The BBU 10 includes a computer as a modulation / demodulation unit 11, a radio signal power adjustment unit 31, frequency conversion units 13 and 17, an adder 19, a signal extraction unit 16, a D / A conversion unit 12, and an A / D conversion unit 18. It may be realized by making it function. In this case, each configuration is realized by a CPU (Central Processing Unit) in the BBU 10 executing a computer program stored in a storage unit (not shown). The RRH 20 may be realized by causing a computer to function as the signal extraction unit 22, the frequency conversion units 23 and 28, the adder 30, the A / D conversion units 41 and 43, and the D / A conversion units 42 and 44. In this case, each configuration is realized by the CPU in the RRH 20 executing a computer program stored in a storage unit (not shown).

(Embodiment 2-2)
In Embodiment 2-2, power adjustment is performed on the RRH 20 side during uplink communication. The apparatus configuration of the BBU 10 when the embodiment 2-2 is applied is the same as that of the embodiment 1-1.

  FIG. 15 shows a device configuration example of the RRH 20 according to the embodiment 2-2. Unlike the embodiment 1-1, the RRH 20 of the present embodiment includes a radio signal-specific power adjustment unit 61.

  FIG. 16 shows an example of the uplink distributed wireless communication base station communication method according to this embodiment. The uplink distributed wireless communication base station communication method according to this embodiment includes a power adjustment procedure (S213) between the digital conversion procedure (S201) and the IF conversion procedure (S202) described in the embodiment 1-1. Also have.

  In the power adjustment procedure (S213), the power adjustment unit 61 for each radio signal performs power adjustment on the signal of each antenna 26 from the A / D conversion unit 43. The power value to be adjusted is determined according to the frequency characteristics of devices such as the D / A converter 44 and the O / E converter 15. A device configuration example of the radio signal-specific power adjustment unit 61 is the same as the radio signal-specific power adjustment unit 31 illustrated in FIG. 13.

  The embodiment 2-2 is applicable not only to the embodiment 1-1 but also to the embodiment 1-2.

  The BBU 10 may be realized by causing a computer to function as the modem unit 11, the frequency conversion units 13 and 17, the adder 19, the signal extraction unit 16, the D / A conversion unit 12, and the A / D conversion unit 18. Good. In this case, each configuration is realized by the CPU in the BBU 10 executing a computer program stored in a storage unit (not shown). The RRH 20 causes the computer to function as a signal extraction unit 22, frequency conversion units 23 and 28, an adder 30, A / D conversion units 41 and 43, D / A conversion units 42 and 44, and a radio signal-specific power adjustment unit 61. It may be realized. In this case, each configuration is realized by the CPU in the RRH 20 executing a computer program stored in a storage unit (not shown).

(Embodiment 2-3)
In Embodiment 2-3, during uplink or downlink communication, the power value or EVM (Error Vector Magnitude) value of each radio band of the received signal is frequency-converted to an IF band different from that of the radio signal and transmitted to the transmitting side. To transmit. The transmission side performs power adjustment based on these pieces of information.

  FIG. 17 shows a device configuration example of the BBU 10 according to the present embodiment. Unlike the first embodiment, the BBU 10 according to the present embodiment differs from the first embodiment in that the control signal extraction unit 32 extracts an IF band signal with an uplink signal and adjusts the IF band control signal to a baseband band for power adjustment of downlink communication. Has a frequency conversion unit (IF band # N + 1 → BB) 33 for down-conversion. The control signal is input to the adjustment power determination unit 311 of the radio signal-specific power adjustment unit 31 to determine the power value for each radio signal. In addition, for power adjustment of uplink communication, a control signal creation unit 34 that calculates and modulates the power value or EVM value of each radio signal received in the uplink, and the created control signal is separated from each radio signal. Frequency converter (BB → IF # N + 1) 35 for up-conversion to the IF band.

  FIG. 18 shows a device configuration example of the RRH 20 according to the present embodiment. Unlike the first embodiment, the RRH 20 according to the present embodiment calculates and modulates the power value or EVM value of each radio signal received in the downlink for power adjustment of the downlink communication, A frequency converter (BB → IF # N + 1) 55 is provided for up-converting the generated control signal to an IF band different from each radio signal. Further, for power adjustment of uplink communication, a control signal extraction unit 63 that extracts an IF band signal with a downlink signal, and a frequency conversion unit (IF band # N + 1 →) that down-converts the IF band control signal into a baseband band. BB) 56. The control signal is input to the adjustment power determination unit 311 of the radio signal-specific power adjustment unit 61, and the power value for each radio signal is determined.

  FIG. 19 shows an example of a downlink distributed radio communication base station communication method according to this embodiment. The downlink distributed wireless communication base station communication method according to the present embodiment further includes a power adjustment procedure (S113) before the IF conversion procedure (S101) described in the embodiment 1-1.

  In the power adjustment procedure (S113), the radio signal-specific power adjustment unit 31 performs power adjustment on the signal for each antenna #i output from the modem unit 11. At this time, the adjustment power determination unit 311 of the radio signal power adjustment unit 31 determines the power value based on the control signal from the frequency conversion unit 33. The control signal from the frequency conversion unit 33 is a control signal created by the control signal creation unit 62. For this reason, the system according to the present embodiment can make the power value and / or EVM value of each radio band of the received signal during downlink communication appropriate.

  FIG. 20 shows an example of an uplink distributed wireless communication base station communication method according to this embodiment. The downlink distributed wireless communication base station communication method according to this embodiment includes a power adjustment procedure (S213) between the digital conversion procedure (S201) and the IF conversion procedure (S202) described in the embodiment 1-1. Also have.

  In the power adjustment procedure (S213), the power adjustment unit 61 for each radio signal performs power adjustment on the signal of each antenna 26 from the A / D conversion unit 43. At this time, the adjustment power determination unit 311 of the radio signal power adjustment unit 61 determines the power value based on the control signal from the frequency conversion unit 56. The control signal from the frequency conversion unit 56 is a control signal created by the control signal creation unit 34. For this reason, the system according to the present embodiment can make the power value and / or EVM value of each radio band of the received signal during uplink communication appropriate.

  Embodiment 2-3 is applicable not only to Embodiment 1-1 but also Embodiment 1-2.

  In the system according to the present embodiment, since the BBU 10 includes the control signal creation unit 34 and the frequency conversion unit 35, and the RRH 20 includes the control signal extraction unit 63, the frequency conversion unit 56, and the power adjustment unit 61 for each radio signal, downlink communication is performed. The power value and / or EVM value of each radio band of the received signal at the time can be made appropriate. Thus, by performing power adjustment for each radio signal, the number of radio signals that satisfy the required signal quality increases.

  In the system according to the present embodiment, the RRH 20 includes the control signal creation unit 62 and the frequency conversion unit 55, and the BBU 10 includes the control signal extraction unit 32, the frequency conversion unit 33, and the radio signal-specific power adjustment unit 31, and therefore, uplink communication. The power value and / or EVM value of each radio band of the received signal at the time can be made appropriate. Thus, by performing power adjustment for each radio signal, the number of radio signals that satisfy the required signal quality increases.

  In the present embodiment, it is easy to change the IF frequency and the number of IF frequencies by frequency conversion utilizing a DSP during communication of control signals of the BBU 10 and the RRH 20. By signal extraction using DSP, filtering processing with a narrow transition bandwidth can be realized without being limited to analog devices, and the frequency interval of radio signals can be narrowed.

  The BBU 10 includes a modem, a modulation / demodulation unit 11, frequency conversion units 13, 17, 33, 35, an adder 19, a signal extraction unit 16, a D / A conversion unit 12, an A / D conversion unit 18, and a control signal extraction unit. 32, may be realized by functioning as the control signal creation unit 34. In this case, each configuration is realized by the CPU in the BBU 10 executing a computer program stored in a storage unit (not shown). The RRH 20 includes a signal extraction unit 22, frequency conversion units 23, 28, 55, and 56, an adder 30, A / D conversion units 41 and 43, D / A conversion units 42 and 44, a control signal extraction unit 63, You may implement | achieve by functioning as the control signal preparation part 62. FIG. In this case, each configuration is realized by the CPU in the RRH 20 executing a computer program stored in a storage unit (not shown).

  The present invention can be applied to the information communication industry.

10: BBU
11: Modulator / Demodulator 12: D / A Converter 13: Frequency Converter 14: E / O Converter 15: O / E Converter 16: Signal Extractor 17: Frequency Converter 18: A / D Converter 19: Addition Device 20: RRH
21: O / E conversion unit 22: signal extraction unit 23: frequency conversion unit 24: amplifier 25: transmission / reception switching unit 26: antenna 27: amplifier 28: frequency conversion unit 29: E / O conversion unit 30: adder 31: wireless Signal-specific power adjustment unit 32: control signal extraction unit 33: frequency conversion unit (IF band # N + 1 → BB)
34: Control signal generator 35: Frequency converter (BB → IF # N + 1)
41: A / D converter 42: D / A converter 43: A / D converter 44: D / A converter 51: Frequency converter (IF # i → IF # a) (i = 1, 2, 3 ... N)
52: Frequency converter (IF # a → RF)
53: Frequency converter (RF → IF # a)
54: Frequency converter (IF # a → IF # i) (i = 1, 2, 3,... N)
55: Frequency converter (BB → IF # N + 1)
56: Frequency converter (IF band # N + 1 → BB)
61: Power adjustment unit for each radio signal 62: Control signal creation unit 63: Control signal extraction unit

Claims (16)

The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A distributed radio communication base station system that connects the BBU and the RRH by connecting with an optical fiber and transmitting the radio signal in an analog RoF (Radio over Fiber) transmission system,
The BBU is
An IF converter that converts the frequency of the digital electric signal to be transmitted to the RRH into a different IF (Intermediate Frequency) band for each radio signal;
An analog converter that converts each signal from the IF converter into an analog value;
An optical conversion unit that converts an electrical signal from the analog conversion unit into an optical signal and transmits the optical signal to the RRH, and
The RRH is
An electrical converter for converting an optical signal from the BBU into an electrical signal;
A digital converter that converts a signal from the electrical converter into a digital value;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band;
An RF converter that converts the frequency of each IF band separated by the signal extraction unit into an RF (Radio Frequency) band corresponding to the plurality of antennas;
An analog conversion unit that converts a signal from the RF conversion unit into an analog value and outputs the analog value, and
Distributed wireless communication base station system. The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A distributed radio communication base station system that connects the BBU and the RRH by connecting with an optical fiber and transmitting the radio signal in an analog RoF (Radio over Fiber) transmission system,
The BBU is
An IF converter that converts the frequency of the digital electrical signal to be transmitted to the RRH into a different IF band for each radio signal;
An analog converter that converts each signal from the IF converter into an analog value;
An optical conversion unit that converts an electrical signal from the analog conversion unit into an optical signal and transmits the optical signal to the RRH, and
The RRH is
An electrical converter for converting an optical signal from the BBU into an electrical signal;
A digital converter that converts a signal from the electrical converter into a digital value;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band;
A specific frequency converter that converts the frequency of each IF band separated by the signal extraction unit into a predetermined IF band;
An analog conversion unit that converts an output signal of the specific frequency conversion unit into an analog value;
An RF conversion unit that changes the frequency of the output signal from the analog conversion unit to an RF band corresponding to the plurality of antennas,
Distributed wireless communication base station system. The BBU is
The power adjustment part which adjusts the signal power transmitted to the RRH according to the level of the frequency of each IF band in which the frequency conversion of the IF conversion part is performed in the previous stage of the IF conversion part. 3. A distributed radio communication base station system according to 1 or 2. The RRH is
A control signal for generating a control signal for adjusting the signal power of each IF band in the power adjustment unit based on the power value or EVM (Error Vector Magnitude) value of each IF band signal separated by the signal extraction unit The creation department;
A control IF converter that converts the control signal generated by the control signal generator into an IF band for control signal transmission;
An analog converter that converts the output signal of the control IF converter from a digital value to an analog value;
An optical converter that converts an electrical signal from the analog converter into an optical signal and transmits the optical signal to the BBU;
Further comprising
The BBU is
An electrical converter that converts an optical signal from the RRH into an electrical signal;
A digital converter that converts a signal from the electrical converter into a digital value;
A control signal extractor for separating the IF band for transmitting the control signal from the output signal of the digital converter;
A control BB converter that converts the IF band for transmission of the control signal separated by the control signal extractor to a BB (baseband) band;
With
The power adjustment unit in the BBU adjusts the signal power of each IF band according to a control signal from the control BB conversion unit,
The distributed radio communication base station system according to claim 3. The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A distributed radio communication base station system that connects the BBU and the RRH by connecting with an optical fiber and transmitting the radio signal in an analog RoF (Radio over Fiber) transmission system,
The RRH is
A digital converter that converts each of the radio signals received by the antenna into a digital value;
An IF converter that converts the frequency of the signal from the digital converter to a different IF band for each wireless signal;
An analog converter that converts each signal from the IF converter into an analog value;
An optical conversion unit that converts an electrical signal from the analog conversion unit into an optical signal and transmits the optical signal to the BBU, and
The BBU is
An electrical converter that converts an optical signal from the RRH into an electrical signal;
A digital converter that converts a signal from the electrical converter into a digital value;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band;
A BB conversion unit that converts each IF band separated by the signal extraction unit into a BB (baseband) band;
A demodulator that demodulates each radio signal received by the antenna using a digital signal from the BB converter;
Distributed wireless communication base station system. The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A distributed radio communication base station system that connects the BBU and the RRH by connecting with an optical fiber and transmitting the radio signal in an analog RoF (Radio over Fiber) transmission system,
The RRH is
A specific frequency converter that converts the frequency of a radio signal received by the antenna to a predetermined IF band;
A digital converter that converts an output signal from the specific frequency converter into a digital value;
An IF converter that converts the frequency of the signal from the digital converter to a different IF band for each wireless signal;
An analog converter that converts each signal from the IF converter into an analog value;
An optical conversion unit that converts an electrical signal from the analog conversion unit into an optical signal and transmits the optical signal to the BBU, and
The BBU is
An electrical converter that converts an optical signal from the RRH into an electrical signal;
A digital converter that converts a signal from the electrical converter into a digital value;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band;
A BB converter that converts the frequency of each IF band separated by the signal extractor into a BB band;
A demodulator that demodulates each radio signal received by the antenna using a digital signal from the BB converter;
Distributed wireless communication base station system. The RRH is
A power adjustment unit is further provided between the digital conversion unit and the IF conversion unit to adjust the signal power to be transmitted to the BBU according to the frequency of each IF band for frequency conversion of the IF conversion unit. 7. The distributed radio communication base station system according to claim 5 or 6, characterized in that: The BBU is
A control signal generating unit that generates a control signal for adjusting the signal power of each IF band in the power adjustment unit based on the power value or EVM value of each IF band signal separated by the signal extraction unit;
A control IF converter that converts the control signal generated by the control signal generator into an IF band for control signal transmission;
An analog converter that converts the output signal of the control IF converter from a digital value to an analog value;
An optical conversion unit that converts an electrical signal from the analog conversion unit into an optical signal and transmits the optical signal to the RRH;
Further comprising
The RRH is
An electrical converter for converting an optical signal from the BBU into an electrical signal;
A digital converter that converts a signal from the electrical converter into a digital value;
A control signal extractor for separating the IF band for transmitting the control signal from the output signal of the digital converter;
A control BB converter that converts the frequency of the IF band for transmission of the control signal separated by the control signal extractor into a BB band;
With
The power adjustment unit in the RRH adjusts the signal power of each IF band according to a control signal from the control BB conversion unit,
The distributed wireless communication base station system according to claim 7. The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A communication method of the BBU in a distributed wireless communication base station system in which the wireless signal is connected by an optical fiber and is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method,
An IF conversion procedure in which the IF conversion unit converts the frequency of the digital electric signal transmitted to the RRH into a different IF (Intermediate Frequency) band for each radio signal;
An analog conversion unit converts each signal from the IF conversion unit into an analog value, and an analog conversion procedure;
In order,
An electrical signal from the analog conversion unit is converted into an optical signal and transmitted to the RRH.
The BBU communication method in the distributed wireless communication base station system. The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A communication method of the RRH in a distributed radio communication base station system in which the radio signal is connected by an optical fiber and is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method,
A digital conversion procedure in which a digital conversion unit converts an analog signal obtained by converting an optical signal from the BBU into an electrical signal into a digital value;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band; and
An RF conversion procedure in which an RF conversion unit frequency-converts each IF band separated by the signal extraction unit into an RF band according to the plurality of antennas;
An analog conversion unit that converts a signal from the RF conversion unit into an analog value and outputs the analog value to the antenna;
The RRH communication method in the distributed radio communication base station system comprising: The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A communication method of the RRH in a distributed radio communication base station system in which the radio signal is connected by an optical fiber and is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method,
A digital conversion procedure in which a digital conversion unit converts an analog signal obtained by converting an optical signal from the BBU into an electrical signal into a digital value;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band; and
A specific frequency conversion unit, a down-conversion procedure for frequency-converting each IF band separated by the signal extraction unit to a predetermined IF band;
An analog conversion unit converts an output signal of the specific frequency conversion unit into an analog value; and
An RF conversion procedure in which the RF conversion unit changes the frequency of the output signal from the analog conversion unit to an RF band corresponding to the plurality of antennas;
The RRH communication method in the distributed radio communication base station system comprising: The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are divided. A communication method of the BBU in a distributed wireless communication base station system in which the wireless signal is connected by an optical fiber and is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method,
A digital conversion procedure in which a digital conversion unit converts a signal obtained by converting an optical signal from the RRH into an electric signal;
A signal extraction unit for separating the output signal of the digital conversion unit for each IF band; and
A BB conversion procedure in which a BB conversion unit converts each IF band separated by the signal extraction unit into a BB (baseband) band;
In order,
A demodulator demodulates each radio signal received by the antenna using a digital signal from the BB converter,
The BBU communication method in the distributed wireless communication base station system. The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are A communication method of the RRH in a distributed radio communication base station system in which the radio signal is connected by an optical fiber and is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method,
A digital conversion procedure for converting each of the radio signals received by the antenna into a digital value;
IF conversion unit, frequency conversion of the signal from the digital conversion unit to different IF band for each wireless signal,
An analog conversion unit converts each signal from the IF conversion unit into an analog value, and an analog conversion procedure;
In order,
An electrical signal from the analog conversion unit is converted into an optical signal and transmitted to the BBU.
The RRH communication method in the distributed radio communication base station system. The function of the base station that transmits and receives radio signals to and from the radio terminal is divided into a signal processing device (BBU: Base Band Unit) and a radio device (RRH: Remote Radio Head) equipped with a plurality of antennas, and the BBU and the RRH are A communication method of the RRH in a distributed radio communication base station system in which the radio signal is connected by an optical fiber and is transmitted between the BBU and the RRH by an analog RoF (Radio over Fiber) transmission method,
A down-conversion procedure in which the specific frequency conversion unit converts the frequency of the radio signal received by the antenna into a predetermined IF band;
A digital conversion procedure in which the digital conversion unit converts the output signal from the specific frequency conversion unit into a digital value;
IF conversion unit, frequency conversion of the signal from the digital conversion unit to different IF band for each wireless signal,
An analog conversion unit converts each signal from the IF conversion unit into an analog value, and an analog conversion procedure;
In order,
An electrical signal from the analog conversion unit is converted into an optical signal and transmitted to the BBU.
The RRH communication method in the distributed radio communication base station system.   The BBU communication program for making a computer perform each procedure in the communication method of Claim 9 or 12.   15. An RRH communication program for causing a computer to execute each procedure in the communication method according to claim 10, 11, 13, or 14.

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