KR100259143B1 - Apparatus for relaying wireless communication signal - Google Patents

Abstract

PURPOSE: An apparatus for relaying RF signals is provided to relay cellular communication signals in a radio wave shadow area of a cellular communication system. CONSTITUTION: An RF signal repeater(22) is comprised of a cellular transceiver unit(30), a modulation/demodulation unit(32), and an M/W(MicroWave) transceiver unit(34). The cellular transceiver unit(30), receiving a cellular signal from a base station, amplifies and outputs the signal. The cellular transceiver unit(30), receiving a cellular signal to be transmitted to the base station from the modulation/demodulation unit(32), amplifies and outputs the signal. The modulation/demodulation unit(32) sets up, controls and monitors the operations of the RF signal repeater(22). The M/W transceiver unit(34) transmits and receives a microwave of 18GHz or 23GHz with the other RF signal repeater(24). Between the cellular transceiver unit(30) and the modulation/demodulation unit(32) a service signal is exchanged. A control signal is exchanged between the M/W transceiver unit(34) and the modulation/demodulation unit(32) together with the service signal.

Description

Wireless signal repeater

The present invention relates to a cellular communication system, and more particularly to a cellular communication signal relay.

Due to the development of wireless communication technology, various kinds of mobile communication systems are currently commercialized, one of which is a cellular communication system. In a cellular communication system, a service target area is divided into a plurality of cells, and one or more wireless base stations are installed in each cell. Each base station is assigned a plurality of sets of frequency channels, which are connected by means of a radio link with a mobile station, i. Each base station is usually connected to a wireless switching center by using a coaxial cable or an optical cable, and the wireless switching center is connected to a general public telecommunication network (PSTN) by an optical cable. In addition, the frequency channel used in each base station is reused by other base stations apart from each other at sufficient distance, thereby maximizing subscriber capacity by making full use of a given frequency band.

In the case of configuring such a cellular communication system, radio wave propagation is interrupted by a mountain, a building, or the like, so that a radio wave shadow area exists where communication between the base station and the terminal is disturbed. If the radio shadow area exists, the communication channel is not formed when the terminal is located in the shadow area, and the call cannot be initiated. You will be disconnected. Accordingly, there is a problem that the quality of communication service is significantly reduced.

Conventional methods for reducing the shadow area generally reduce the size of each cell into microcells. However, this method has a problem of increasing the facility investment burden of the service provider. In order to reduce the burden of facility investment, there is a method of introducing microcells in shaded areas as well as populated areas. However, even in this case, the burden of the facility investment of the telecommunication service provider is very large, which requires not only a separate base station facility for the shaded area, but also a communication line from the switching center to the base station, which must be maintained. Because. In addition, the introduction of separate base station equipment in the shaded area is complicated by the overall adjustment of the frequency reuse pattern with neighboring base stations. In particular, when there is not much call demand in such a shaded area, a channel that can be used for an adjacent channel is reduced in proportion to the number of channels allocated to a corresponding base station, thereby reducing a subscriber capacity of the system as a whole. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides a wireless signal relay device having a simple structure and a small size for relaying cellular communication signals in a radio wave shadow area of a cellular communication system.

1 is a view showing a wireless communication system using a wireless signal relay apparatus according to the present invention.

Figure 2 is a block diagram of a preferred embodiment of a radio signal relay apparatus according to the present invention.

3 is a block diagram illustrating the cellular transceiver of FIG. 2.

4 is a block diagram illustrating the modulation and demodulation unit of FIG. 2.

5 is a block diagram illustrating a microwave transceiver of FIG. 2.

The wireless signal relay device of the present invention for achieving the technical problem is operated in two pairs, and relays the wireless signal transmission between the base station and the mobile station.

The cellular transceiver receives the first cellular signal inputted and amplified and outputs the amplified first cellular signal to the demodulator, and amplifies and copies the second cellular signal outputted from the modulated demodulator through an antenna.

The modulation and demodulation unit generates and modulates a first supervisory control signal for requesting a signal amplification rate change in another pair of radio signal relays, and transmits the modulated first supervisory signal to the microwave transceiver. The modulator demodulates the second cellular signal output from the microwave transceiver and the modulated second supervisory control signal, demodulates the modulated second supervisory control signal, and demodulates the second supervisory control signal according to the demodulated second supervisory control signal. Amplifies a cellular signal and outputs the amplified second cellular signal to the cellular transceiver.

The microwave transceiver transmits the band of the first cellular signal and the modulated first supervisory control signal output from the modulation and demodulation unit to a microwave to copy it to another pair of wireless signal relays. In addition, the microwave transceiver receives and amplifies the modulated second supervisory control signal and the second cellular signal copied from the another radio signal repeater and transitions the band of the amplified signal to the cellular signal band, the frequency shifted And outputs a second cellular signal and a modulated second supervisory control signal to the modulator.

The cellular transceiver, the modulation and demodulation unit, and the microwave transceiver may be manufactured as one module that is functionally connected and structurally integrated.

The first cellular signal may be a downlink cellular signal and the second cellular signal may be an uplink cellular signal, whereas the first cellular signal may be an uplink cellular signal and the second cellular signal may be a downlink cellular signal.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 shows a wireless communication system using a wireless signal relay device according to the present invention. As shown, the service area is divided into a plurality of cells 12 and 14, and one base station 16 is provided in each cell 12 and 14. The base station 16 may be connected by a radio link with a mobile station 18 in a cell. In addition, the base station 16 is physically connected to the wireless switching center 10 by a dedicated line 20 having a coaxial cable or an optical cable type, and the wireless switching center 10 is connected to a general public telecommunication network (PSTN) by an optical cable. .

The wireless switching center 10 controls the communication channel routing from the public telecommunications network to the base station 16 near the mobile station in order to connect a call from the public telecommunications network to the mobile station 18. The radio switching station 10 also controls channel routing from the terminal to the public telecommunications network, and controls channel routing between the base stations to mediate calls between mobile stations.

When there is not much big obstacle between the base station 16 and the mobile station 18, so that direct communication is possible between the base station 16 and the mobile station 18, the communication is started as follows. When the mobile station 18 wants to start a call, a control message is sent to the nearest base station 16. When the base station 16 receives the call request message, the base station 16 transmits the telephone number of the call counterpart to the wireless switching center 10, and in response, the switching center 10 connects the call.

On the other hand, when a call is made to the mobile station 18 from the PSTN or another mobile station, the radio switching station 10 first transmits the call information to all the base stations 16. In response, each base station 16 transmits a paging message in its cell area. If the mobile station 18 receives the paging message, the mobile station 18 transmits a control message to the base station 16. The base station 16 receiving the control message informs the radio switching station 10 that the mobile station is in its own jurisdiction, and the call is started under the control of the radio switching station 10.

On the other hand, in the communication system of FIG. 1, if the communication between the base station and the mobile station is not possible or suitable due to a mountain or other feature or artificial structure, the communication between the base station and the mobile station is performed by the radio signal relay devices 22 of the present invention. , 24).

The repeater 22 accepts the cellular communication signal to be transmitted from the base station 16 to the mobile station 26, transitions the frequency band of the cellular communication signal into microwaves and transmits the microwave signal to the relay device 24. The relay device 24 receives the microwave signal, extracts the cellular communication signal contained therein, and re-copys it again, and the terminal 26 receives the re-radiated cellular signal.

Conversely, looking at the cellular communication signal transmitted from the mobile station 26 to the base station 16, the relay device 24 receives the cellular signal output from the mobile station 26, and shifts the frequency band of the cellular signal into a microwave. The microwave signal is transmitted to the relay device 22. The repeater 22 accepts the microwave signal, extracts the cellular signal contained therein and re-copys it again, and the base station 16 receives the re-radiated cellular signal.

Except that the cellular signal is relayed by the relays 22 and 24, the process of initiating a call between the base station 16 and the mobile station 26 and the process of hand hoping with another base station are performed by the mobile station ( Same as the usual procedure performed for 18).

That is, when the mobile station 26 wants to start a call, a control message is sent to the nearest base station 16 via the relays 22, 24. When the base station 16 receives the call request message, the base station 16 transmits the telephone number of the call counterpart to the wireless switching center 10, and in response, the switching center 10 connects the call.

On the other hand, when a call is made to the mobile station 26 from the PSTN or another mobile station, the radio switching station 10 first transmits the call information to all the base stations 16. In response, each base station 16 transmits a paging message in its cell area. The relay device 22 receives the paging message and sends it to the relay device 24, which repeats the transmitted paging message at the cellular frequency. If the mobile station 26 receives the paging message, the mobile station 26 transmits a control message to the base station 16 via the relay devices 24 and 22. The base station 16 receiving the control message informs the radio switching station 10 that the mobile station is in its own jurisdiction, and the call is started under the control of the radio switching station 10.

As such, the radio signal relays of the present invention are installed in pairs, and each radio signal relay device performs a symmetrical function and has almost the same configuration. In the following description, in describing any one of the two wireless signal relays 22 and 24, the term "power" will be used when referring to the other.

2 is a block diagram of a preferred embodiment of the wireless signal relay of FIG. The radio signal relays 22 and 24 include a cellular transceiver 30, a modulator 32, and a microwave (M / W) transceiver 34.

The cellular transceiver 30 receives, amplifies, and outputs a cellular signal from the base station 16. In addition, the cellular transceiver 30 receives a cellular signal to be transmitted to the base station 16 from the modulator 32, amplifies and outputs it. The modulation and demodulation unit 32 is for setting, controlling and monitoring the operation of the radio signal relay. The microwave (M / W) transceiver 34 transmits and receives a microwave in an 18 GHz or 23 GHz band with a power station. On the other hand, a service signal is exchanged between the cellular transceiver 30 and the modulation and demodulation unit 32, and a control signal is exchanged with the service signal between the modulation and demodulation unit 32 and the M / W transceiver 34.

In a preferred embodiment of the present invention, these radio signal relays 22, 24 are manufactured as one piece. However, when it is necessary to keep the distance between the cellular transmission and reception antenna and the microwave transmission and reception antenna due to geographic requirements, the cellular transmission and reception unit 30, the modulation and demodulation unit 32 and the microwave (M / W) transmission and reception Each of the sections 34 may be manufactured as a separate module, or only one module may be manufactured as a total of two modules, and each module may be connected by a coaxial cable.

3 is a block diagram illustrating the cellular transceiver 30 of FIG. 2.

The cellular signal radiated from the base station is input through the antenna 42. The cellular signal is in the range of 869 to 894 MHz or 1.84 to 1.87 MHz, and the specific range is determined according to the communication service provider using the relay device. The low noise amplifier 44 amplifies the cellular signal and outputs it to the demodulation unit 32 as the cellular input signal CS_IN. The power amplifier 46 receives and amplifies the cellular output signal CD_OUT input from the modulation and demodulation unit 32. The amplified signal is radiated through the antenna 48 to reach the base station. The radiated cellular signal is in the range of 824-849 MHz or 1.75-1.78 MHz, and likewise the specific range is determined by the carrier. On the other hand, the transmitting and receiving antennas 42 and 48 may use antennas for cellular base station levels. Since these antennas are inexpensive, they are used separately for transmission and reception in this embodiment. However, in another embodiment of the present invention, a diplexer may be used and only one antenna may be used.

4 is a block diagram illustrating the modulation and demodulation unit 32 of FIG. 2.

The cellular input signal CS_IN input from the cellular transceiver 30 is mixed with the supervisory control signal by the coupler 50 and then output as a high frequency output signal RF_OUT. The microprocessor 52 generates and outputs a supervisory control signal indicating the degree of attenuation of the transmitted signal. The modulator 54 modulates the supervisory control signal using the frequency output from the oscillator (second). In this embodiment, the modulation technique used in the modulator 54 is binary phase shift keying (BPSK) modulation. In another embodiment of the present invention, another modulation technique such as quadrature phase shift keying (QPSK) modulation is used. It may be.

The oscillator 56 is configured using an OCXO (Oven Controlled Crystal Oscillator), a divider and a PLL, and divides and locks a frequency oscillated by the OCXO to generate a subcarrier for transmitting a supervisory control signal. do. The subcarrier has a frequency that is about 1 to 4 MHz lower than the lower end of the band of the cellular signal CS_IN. However, this value is merely exemplary and may vary depending on the government's frequency allocation policy, the operator's situation and the bandwidth of the supervisory control signal.

On the other hand, the band pass filter 60 receives the high frequency input signal RF_IN input from the M / W transceiver 34 and performs filtering. The filtered signal is amplified by the amplifier 62. The amplified signal is converted into a signal including the baseband signal while passing through the mixer 64, and the gain is adjusted by the variable gain amplifier 66. The bandpass filter 68 excludes the supervisory control signal from the amplified baseband signal and extracts only the cellular signal. The mixer 70 and the bandpass filter 74 raise the frequency band of the cellular signal by the frequency of the signal output from the oscillator 72, restore the frequency band of the same as the normal cellular service signal, and restore the band. Is output to the cellular transceiver 30 as the cellular output signal CS_OUT. As the oscillator 72, an oscillator using OCXO is used.

On the other hand, the signal output from the variable gain amplifier 66 is also supplied to the low pass filter 76. The low pass filter 76 extracts only a supervisory control signal from the baseband signal. The amplifier 78 amplifies the supervisory control signal, and the low pass filter 80 performs low pass filtering again to remove noise introduced from the amplifier. The filtered signal is demodulated by BPSK or QPSK in the demodulator 82, and is accurately reproduced by the supervisory control signal transmitted from the microprocessor of the power station.

In addition, the demodulator 82 may determine the degree of attenuation of the signal by comparing the magnitude of the demodulated monitoring control signal with an experimental value previously obtained in advance and stored in the internal memory. According to this degree of signal attenuation, demodulator 82 adjusts the gain of variable gain amplifier 66. On the other hand, the demodulator 82 separately outputs the degree of attenuation of the signal to the microprocessor 52, so that the microprocessor 52 may request that the gain of the transmission signal be increased or decreased by the microprocessor 52 of the large country.

Meanwhile, in FIG. 4, the low pass filter 84 filters the supervisory control signal demodulated by the demodulator 82 to form a control voltage for the voltage controlled oscillator (VCO) 86. The voltage controlled oscillator 86 outputs a frequency that varies according to the control voltage. The output signal of the voltage controlled oscillator 86 is input to the mixer 64 via the mixer 88 and the bandpass filter 89. Accordingly, the loop including the low pass filter 84 and the voltage controlled oscillator 86 constitutes a PLL circuit. By this PLL circuit, the frequency deviation of the Dielectric Resonance Oscillator (DRO), which will be described later, is eliminated in the two repeaters that transmit and receive microwave signals, and only the frequency deviation of the OCXO is used to demodulate the signals transmitted between the two repeaters. This affects.

On the other hand, in the present embodiment, the microprocessor 52 of the modulation and demodulation unit 32 may be connected to the base station through a LAN or a modem to exchange network management signals. An example of the network management signal may be an equipment status signal of a relay device. Although not shown, in the relay device of the present invention, the cellular transceiver 30 and the M / W transceiver 34 have their own microprocessor and several sensors. The sensors detect whether the door of the device is open, whether the cooling fan is operating, the ambient temperature, whether the amplifier is operating, and report the result to the microprocessor. The report content is notified to the microprocessor 52 of the modulation / demodulation unit 32, and the microprocessor 52 transmits the notice content to the power station or the base station according to the notification content. In FIG. 4, the signal NMS_I / O indicates a network management signal input and output in this manner.

As such, the network management signal transmitted between the microprocessors of the cellular transceiver 30 and the M / W transceiver 34 and the microprocessor 52 of the modulation / demodulation unit 32, and between the relay apparatus and the base station of the present invention. The transmitted network management signal is modulated and exchanged by frequency shift keying (FSK).

FIG. 5 is a block diagram illustrating the M / W transceiver 34 of FIG. 2.

The mixer 92 receives a high frequency input signal RF_IN in which a service signal and a monitoring control signal are mixed from the modulation / demodulation unit 32. As the high frequency oscillators 94 and 108, a dielectric resonance oscillator (DRO) is used. These high frequency oscillators 94, 108 oscillate a frequency near 18 GHz, 23 GHz or 38 GHz, and in this embodiment an oscillation frequency near 23 GHz is used. This oscillation frequency is used for modulation and demodulation between the service band signal and the microwave band signal.

The mixer 92 and the band pass filter 96 use the oscillation frequency of the high frequency oscillator 94 to raise the frequency band of the high frequency input signal RF_IN of the service band to the microwave band. The power amplifier 98 amplifies the high frequency signal output from the band pass filter 96. A waveguide filter (WG filter) 100 filters the amplified high frequency signal from the power amplifier 98 to have a more precise bandwidth of 21.6-22.2 GHz. The signal filtered by the waveguide filter 100 passes through the circulator 110 and is radiated by the antenna 112 to a power station located in a radio wave shadow area.

Meanwhile, in another embodiment of the present invention, a microwave monolithic integrated circuit (MMIC) may be used instead of the waveguide filter 100. In this case, the MMIC requires that the signal loss is not very large.

The circulator 110 adjusts the signal path so that the signal output from the waveguide filter 100 proceeds only to the antenna 112 and the signal received from the antenna 112 proceeds only to the waveguide filter 102. Meanwhile, in another embodiment of the present invention, the circulator 110 and the two waveguide filters 100 and 102 may be replaced by one diplexer.

On the other hand, the signal transmitted from the power station is received through the antenna 112 and filtered by the waveguide filter 102. In this embodiment, the passband of the waveguide filter 102 is 22.8 to 23.4 GHz. The filtered signal is amplified by the low noise amplifier 104. The amplified signal is multiplied by the output frequency of the high frequency oscillator 108 by the mixer 106 and then output to the demodulation unit 32 as a high frequency input signal RF_IN. As described above, the high frequency input signal RF_IN is filtered by the band pass filter 60 of the modulator 32 to have a frequency band near the service band. On the other hand, the band pass filter 60 of FIG. 4 may be located at the rear end of the mixer 106 in the M / W transceiver 34 of FIG.

On the other hand, as described above, the M / W transceiver 34 has a separate microprocessor built-in, to set the system parameters and monitor the operation of the system. The microprocessor also enables remote network management and setup by communicating with the microprocessor 52 of the modulation and demodulation unit 32. The microprocessor may receive a command from the modulation and demodulation unit 32 to set an amplification factor of the low noise amplifier 104.

As described above, the wireless signal relay of the present invention operates in pairs. However, in order to ensure service stability, two or more relay devices may be installed at each location, and only one of them may be operated, and may be automatically switched in the event of a serious defect in the device. At this time, the 1: 1 switching of the device is determined by the microprocessor 52 based on the network management signal.

Meanwhile, in the present specification, where the confusion may occur with respect to the supervisory control signal, the first supervisory control signal and the second supervisory control signal are separately indicated, and the first supervisory control signal is a signal transmitted from each relay to a power station. And the second supervisory control signal refers to a signal received from a large power. In areas where confusion may not occur, both are labeled as supervisory control signals for the sake of brevity.

As described above, the radio signal relay device of the present invention enables the operator to relay cellular communication signals in the radio shadow area of the cellular communication system without having to construct a separate base station. In particular, the apparatus of the present invention has a simple structure and a small size compared to the base station equipment, thereby reducing the installation cost and the service cost of the service provider.

In addition, since the intensity of the signal can be adjusted by the supervisory control signal exchange between the relay devices of the present invention, the relay loss can be kept constant. This adaptive control of signal strength can greatly help to increase call coverage and retention. In particular, in the case of the CDMA cellular telephone network, the frequency of the terminal requiring the base station to increase the output based on the frame error rate can be reduced, thereby reducing the data processing burden of the base station. Reduce system reliability.

In addition, such a radio signal relay device may be utilized in areas where communication demand is low as well as in the radio shadow area, the network construction and maintenance costs of the telecommunication operators can be greatly reduced.

Claims (6)

In a wireless signal relay device which operates in pairs and relays radio signal transmission between a base station and a mobile station, one radio signal relay device A cellular transceiver for receiving and amplifying an input first cellular signal and outputting the amplified first cellular signal to a demodulator, and for amplifying and copying a second cellular signal output from the modulator and an antenna; Generating and modulating a first monitoring control signal for requesting a change in signal amplification ratio of the paired wireless signal relay unit and transmitting the modulated first supervisory signal to a microwave transceiver; and in the microwave transceiver Receiving an outputted second cellular signal and a modulated second supervisory control signal, demodulating the modulated second supervisory control signal, amplifying the second cellular signal according to the demodulated second supervisory control signal, and amplifying the second cellular signal; The modulation and demodulation unit outputting two cellular signals to the cellular transceiver; And The bands of the first cellular signal and the modulated first supervisory control signal output from the modulation and demodulation unit are shifted to a microwave and copied to another pair of radio signal repeaters, and from another radio signal repeater. Accepts and amplifies the modulated second supervisory control signal and the second cellular signal, and shifts the band of the amplified signal to a cellular signal band to transfer the frequency shifted second cellular signal and the modulated second supervisory control signal to the modulator. And a microwave transmitting and receiving unit for outputting. The wireless signal relay of claim 1, wherein the cellular transceiver, the modulator, and the microwave transceiver are integrated modules. According to claim 1, wherein the modulation and demodulation unit A first microprocessor for generating the monitoring control signal; A modulator for modulating the surveillance control signal; Coupling means for combining the supervisory control signal with the amplified first cellular signal; A variable gain amplifier for amplifying the second cellular signal and the modulated second supervisory control signal output from the microwave transceiver according to a variable gain; Demodulation and gain control means for demodulating the modulated second supervisory control signal to increase or decrease the variable gain in accordance with the magnitude of the demodulated second supervisory control signal; And And a frequency shifting means for restoring a band of the amplified second cellular signal to a cellular signal band. The wireless signal relay of claim 3, wherein the first microprocessor exchanges network management signals with a base station. The apparatus of claim 4, wherein the cellular transceiver and the microwave transceiver comprise second and third microprocessors, and each includes one or more sensors for identifying its own operating state. Wireless signal relay device for transmitting to the first microprocessor. The method of claim 1, wherein the microwave transceiver Microwave antennas; First frequency shifting means for shifting a band of a first cellular signal and a modulated first supervisory control signal output from the modulation and demodulation unit into a microwave; An amplifier for amplifying a modulated second supervisory control signal and a second cellular signal received from said another radio signal repeater; Second frequency shifting means for shifting the band of the amplified signal to a cellular signal band; And And diplexing means for coupling the frequency shifted signal by said first frequency shifting means and the signal received from said another radio signal repeater to said microwave antenna.

Images