KR20130111064A - Repeater for mobile comunication - Google Patents

Repeater for mobile comunication Download PDF

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Publication number
KR20130111064A
KR20130111064A KR1020120033561A KR20120033561A KR20130111064A KR 20130111064 A KR20130111064 A KR 20130111064A KR 1020120033561 A KR1020120033561 A KR 1020120033561A KR 20120033561 A KR20120033561 A KR 20120033561A KR 20130111064 A KR20130111064 A KR 20130111064A
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KR
South Korea
Prior art keywords
signal
frequency
master unit
unit
digital
Prior art date
Application number
KR1020120033561A
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Korean (ko)
Inventor
이태훈
정성훈
박종상
Original Assignee
삼지전자 주식회사
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Application filed by 삼지전자 주식회사 filed Critical 삼지전자 주식회사
Priority to KR1020120033561A priority Critical patent/KR20130111064A/en
Publication of KR20130111064A publication Critical patent/KR20130111064A/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/25—Arrangements specific to fibre transmission
    • H04B10/2575—Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
    • H04B10/25752—Optical arrangements for wireless networks
    • H04B10/25758—Optical arrangements for wireless networks between a central unit and a single remote unit by means of an optical fibre
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/155—Ground-based stations
    • H04B7/15528—Control of operation parameters of a relay station to exploit the physical medium
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L7/00—Arrangements for synchronising receiver with transmitter
    • H04L7/0008—Synchronisation information channels, e.g. clock distribution lines

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Radio Relay Systems (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

PURPOSE: A relay device for mobile communication is provided to output a frequency not used for mobile communication while reducing production costs. CONSTITUTION: A remote radio head (110) receives a signal of a first frequency from a digital unit. The remote radio head converts the frequency of the signal into a second frequency. A master unit (120) receives a signal of the second frequency from the remote radio head. The master unit converts the second frequency into an intermediate frequency. A slave unit (130) receives a signal of the intermediate frequency from the master unit. The slave unit converts the signal into the first frequency.

Description

Relay device for mobile communication {Repeater For Mobile Comunication}

The present invention relates to a relay device for mobile communication.

The current generation 4th generation network (LTE) uses a frequency band of 850 [MHz]. Mobile operators are trying to increase the frequency bands used in 4G networks, and thus, the use of frequency bands such as 2.1 [GHz] and 1.8 [GHz] is mentioned. However, mobile communication relay devices currently used do not provide for an additional frequency band, and thus development is required. However, in the development of the relay device, a lot of costs are expected for the development of the hardware, and the issue of the accurate frequency synchronization occurs in the frequency conversion process occurs.

The present invention provides a reliable mobile communication relay device that outputs frequencies other than those used for mobile communication while reducing production costs.

According to an aspect of the present invention, there is provided a mobile communication relay device comprising: a remote radio head for receiving a signal of a first frequency from a digital unit and converting a frequency of the signal into a second frequency; A master unit receiving the signal of a second frequency from the remote radio head and converting it to an intermediate frequency; And a slave unit receiving the signal of an intermediate frequency from the master unit and converting the signal to the first frequency.

Here, the remote radio head may extract a reference clock from the GPS signal of the digital unit and transmit the reference clock to the master unit.

The remote lid head may perform optical communication with the digital unit.

The digital unit may further include a clock recovery module provided separately from the master unit and extracting a reference clock from the GPS signal of the digital unit and transferring the reference clock to the master unit.

In addition, the master unit may perform radio frequency communication with the remote radio head.

In addition, the master unit may convert the signal of the first frequency into a signal of the intermediate frequency by combining with the received reference clock.

In addition, the master unit may convert the signal of the first frequency through an attenuator and an amplifier and then synthesize the signal with the reference clock.

In addition, the master unit may convert the signal of the intermediate frequency into the form of a digital signal through an analog-to-digital converter, and remove the noise through a digital filter.

In addition, the master unit may transmit a signal in the form of the digital signal to the slave unit using optical communication.

In addition, the slave unit may receive the signal of the intermediate frequency, combine with a reference clock and convert the signal of the second frequency.

In the relay device according to the present invention, the production unit can be reduced by using the master unit of the existing frequency band in using the master unit.

In addition, the relay device according to the present invention can secure the reliability by reducing the frequency error by extracting and using the reference clock applied to the master unit and the slave unit from the GPS signal of the digital unit.

1 is a schematic diagram of a relay device for mobile communication according to an embodiment of the present invention;
2 is a block diagram of a relay device for mobile communication according to an embodiment of the present invention.
3 is a block diagram illustrating a process of generating a reference clock in the RRH of the relay device for mobile communication according to an embodiment of the present invention.
4 is a block diagram of a master unit of a relay device for mobile communication according to an embodiment of the present invention.
5 is a block diagram illustrating a frequency conversion process in a master unit and a slave unit of a relay device for mobile communication according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

1 is a schematic diagram of a relay device for mobile communication according to an embodiment of the present invention; 2 is a block diagram of a relay device for mobile communication according to an embodiment of the present invention. 3 is a block diagram illustrating a process of generating a reference clock in the RRH of the relay device for mobile communication according to an embodiment of the present invention. 4 is a block diagram of a master unit of a relay device for mobile communication according to an embodiment of the present invention.

First, referring to FIGS. 1 and 2, the repeater 100 for a mobile communication according to an embodiment of the present invention may include a remote radio head 110, a master unit 120, and a slave unit 130. .

The remote radio head (RRH) 110 is connected to a digital unit 10 to receive a signal. At this time, the remote radio head 110 and the digital unit 10 is connected through an optical cable, the signal may be transmitted and received in the form of an optical signal. In addition, the remote radio head 110 may receive the optical signal through optical communication through an optical coupler (110a). The remote radio head 110 has the first frequency at which the input signal is used in a mobile communication network. The first frequency may be, for example, a frequency of 2.1 [GHz] used in a fourth generation communication network.

The remote radio head 110 converts the input signal into an analog signal through the digital analog converter 111. In addition, if necessary, the remote radio head 110 may perform an operation of amplifying by converting to a lower frequency, for example, an intermediate frequency (IF) of several tens of [MHz] through a frequency converter. In this case, the intermediate frequency may be used because the frequency is lower than the frequency of the input signal, so that processing such as amplification or selection is easy.

In addition, the remote radio head 110 converts the frequency of the input signal to have a second frequency again through a frequency converter 112 and transmits the frequency to the master unit 120. In this case, the second frequency may be different from the first frequency, for example, 850 [MHz].

In addition, the remote radio head 110 obtains a reference clock of the digital unit 110 and transmits the reference clock to the master unit 120. In more detail, referring to FIG. 3, the digital unit 10 generates a reference clock 12 from the GPS signal 11 and converts it to a standard in the form of an optical signal through a framer 13. Meanwhile, the remote radio head 110 receiving the same detects an input signal in the form of the optical signal through a reframer 110c and detects a reference clock 110d therefrom, and detects the reference clock. The signal is transferred to the master unit 120 and the slave unit 130 so that the frequency of the input signal can be converted and output.

Alternatively, the remote radio head 110 may not provide a reference clock in some cases, and in this case, a separate clock recovery module 110b is connected to the optical coupler 110a to detect the reference clock. Can be performed. Accordingly, the reference clock may be transmitted to the master unit 120 and the slave unit 130.

At this time, the reference clock is based on the GPS signal, and is an excellent signal having a frequency error characteristic of 0.001 [ppm] or less. Therefore, as will be described later, when the master unit 120 and the slave unit 130 using the same frequency conversion, the frequency error is reduced to meet the 3GPP standard, to ensure the reliability of the relay device 100 can do.

The master unit 120 is connected to the remote radio head 110 to receive an input signal having the second frequency. The master unit 120 may communicate with the remote radio head 110 at a radio frequency. The master unit 120 converts an input signal received from the remote radio head 110 into an intermediate frequency IF through a frequency converter 121, and converts it into a digital signal through an analog-to-digital converter 122. This is transmitted to the slave unit 130 through the optical cable 123.

In more detail, referring to FIG. 4, the master unit 120 receives an output signal of a second frequency from the remote radio head 110, and includes an attenuator, an att, 121a, an amplifier, an amplifier, 121b) is converted into a signal of a desired size. In addition, the master unit 120 generates a frequency having a phase fixed to the reference clock received from the remote radio head 110 through a frequency synthesizer 121c and applies it to a mixer 121d. To mix with the input signal. The intermediate frequency IF is generated as a result of the mixer 121d. At this time, since the remote radio head which receives the second frequency (for example, 850 [Mhz]) and converts it into an intermediate frequency is already used in the existing fourth generation communication network (for example, LTE), the present invention The mobile communication relay device 100 according to the embodiment does not need to separately design and manufacture the remote radio head 120. Therefore, in manufacturing the relay device 100, the manufacturing cost can be reduced.

In addition, the master unit 120 passes the intermediate frequency IF through a low pass filter LPF 124 to remove noise in a high frequency region, and the digital signal through the analog-to-digital converter 122. Can be converted to In addition, the converted digital signal is again subjected to secondary noise removal through the digital filter 125, and finally converted to the optical signal standard through the framer 126, and this is converted to the slave through the optical cable 123 It will be delivered to the unit 130.

The slave unit 130 converts the input signal received from the master unit 120 into a final output. The slave unit 130 may receive a signal through the optical cable 131, change the signal into an analog signal through the digital analog converter 132, and convert the signal into a desired first frequency through the frequency converter 133. have. Accordingly, the slave unit 130 generates an output signal having the same first frequency as that of the input signal received from the digital unit 10, whereby communication using the same, for example, 4 generation communication using 2.1 [GHz], is performed. Make it possible.

Hereinafter, an effect of reducing a frequency error occurring when frequency conversion is performed in the master unit 120 and the slave unit 130 in the mobile communication relay device 100 according to an embodiment of the present invention.

5 is a block diagram illustrating a frequency conversion process in a master unit and a slave unit of a relay device for mobile communication according to an embodiment of the present invention.

Referring to FIG. 5, a reference clock (eg, 10 [MHz]) applied to the frequency synthesizer 121d of the master unit 120 has a frequency error ΔF ref . Accordingly, the output of the frequency synthesizer 121c is represented by the sum (F L + ΔF) of the phase locked frequency F L and the error ΔF.

However, the input signal input to the master unit 120 is a second frequency (for example, 850 [MHz]), while the output signal of the slave unit 130 is a first frequency (for example, 2.1 [GHz]. ]), So that differences F L1 and F L2 occur in the phase-locked frequencies F L applied to each. As a result, the signal applied to the master unit 120 becomes (F L1 + ΔF 1 ), and the signal applied to the slave unit 130 is in the form of (F L2 + ΔF 2 ).

Based on this, the output of the mixer 121d of the master unit 120 to which the input signal F 1 is input becomes (IF-ΔF 1 ), resulting in a first error F 1 . Then, the output passing through the mixer 133a of the slave unit 130 becomes (F 2 + (ΔF 2 -ΔF 1 )), and the error (ΔF 2 -ΔF 1 ) does not cancel in the output. Done.

It is known that there is a frequency error of about 0.1 [ppm] for a reference clock through a thermostat controlled crystal oscillator that is typically used inside a relay device. Therefore, the error ΔF 2 -ΔF 1 that is not finally eliminated becomes a problem as compared with 0.01 [ppm] prescribed by the 3GPP frequency stabilization protocol.

On the other hand, the relay device 100 according to the embodiment of the present invention uses a reference clock extracted from the GPS signal 11 of the digital unit 10 as described above, and the reference clock has a frequency of about 0.001 [ppm]. Has an error. Therefore, even if the error (ΔF 2 -ΔF 1 ) that is not finally eliminated is taken into account, this corresponds to 0.01 [ppm] or less of the 3GPP frequency stabilization protocol and may satisfy the protocol. Therefore, the relay device 100 according to the embodiment of the present invention can secure reliability by performing an accurate frequency conversion compared to the conventional.

What has been described above is just one embodiment for implementing the relay device for mobile communication according to the present invention, and the present invention is not limited to the above embodiment, and as claimed in the following claims, the gist of the present invention Without departing from the scope of the present invention, any person having ordinary skill in the art will have the technical spirit of the present invention to the extent that various modifications can be made.

100; Relay device 110 for mobile communication; Remote radio head
120; Master unit 130; Slave unit
10; Digital unit

Claims (10)

In the relay device for mobile communication,
A remote radio head receiving a signal of a first frequency from a digital unit and converting the frequency of the signal into a second frequency;
A master unit receiving the signal of a second frequency from the remote radio head and converting it to an intermediate frequency; And
And a slave unit receiving the signal of an intermediate frequency from the master unit and converting the signal to the first frequency. The method of claim 1,
And the remote radio head extracts a reference clock from the GPS signal of the digital unit and transmits the reference clock to the master unit. The method of claim 1,
And the remote lido head performs optical communication with the digital unit. The method of claim 1,
And a clock recovery module provided separately from the master unit in the digital unit and extracting a reference clock from the GPS signal of the digital unit and transferring the reference clock to the master unit. The method of claim 1,
And the master unit performs radio frequency communication with the remote radio head. The method of claim 1,
And the master unit converts the signal of the first frequency into a signal of the intermediate frequency by combining with the received reference clock. The method according to claim 6,
And the master unit converts the signal of the first frequency through an attenuator and an amplifier and then combines the signal with the reference clock. The method according to claim 6,
The master unit converts the signal of the intermediate frequency into the form of a digital signal through an analog-to-digital converter, and passes through a digital filter to remove noise. The method of claim 8,
And the master unit transmits the signal in the form of the digital signal to the slave unit using optical communication. The method of claim 1,
And the slave unit receives the signal of the intermediate frequency, combines with a reference clock, and converts the signal into the signal of the second frequency.
KR1020120033561A 2012-03-30 2012-03-30 Repeater for mobile comunication KR20130111064A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10020890B2 (en) 2016-11-29 2018-07-10 Electronics And Telecommunications Research Institute Host unit and remote radio head for distributed antenna system supporting large data traffic

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10020890B2 (en) 2016-11-29 2018-07-10 Electronics And Telecommunications Research Institute Host unit and remote radio head for distributed antenna system supporting large data traffic

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