KR20020044827A - Signal-Sensed Path-Switching Optical Repeater Systems for Relaying CDMA/TDD Signals - Google Patents

Abstract

PURPOSE: A path switching optical repeater by a signal sensor in a CDMA/TDD(Time Division Duplex) mobile system is provided to catch the service states of a forward link and a reverse link and to interrupt the transfer of a forward signal to a reverse receiver. CONSTITUTION: A slave optical repeater in a CDMA/TDD mobile system adopting path switch by a signal sensor consists of an optical transceiver(301), a slave gain controller(302), a splitter(303), a forward band pass filter(305), a variable switch(308), an antenna(306), a reverse band pass filter(305a), a receiver(309), an SCU(Slave Control Unit)(310), a PSU(Power Supply Unit)(311), and a modulator/demodulator(302a). The optical transceiver(301) converts an optical signal, received from a master optical repeater, into an RF signal or converts an RF signal, generated from a terminal, into an optical signal. The slave gain controller(302) controls the gain of an RF signal. The splitter(303) distributes forward signals to an amplifier(304) and a sensor/switch control unit(307). The forward band pass filter(305) removes noise from a forward signal. The variable switch(308) is to select a forward path or a reverse path. The reverse band pass filter(305a) removes noise from a reverse signal. The receiver(309) transfers a reverse signal, received from the terminal, to the slave gain controller(302). The SCU(310) communicates with the MCU(Master Control Unit) of the master optical repeater and controls each of the modules of the slave optical repeater. The PSU(311) supplies power to each of the modules of the slave optical repeater. The modulator/demodulator(302a) makes the SCU(310) receive control data from the MCU or transmit state data to the MCU.

Description

Signal-Sensed Path-Switching Optical Repeater Systems for Relaying CDMA / TDD Signals}

In the third generation mobile communication system represented by the IMT-2000 system, subscribers are expected to use not only voice service but also data service, and the use rate of wireless internet service is expected to be the highest. In wireless Internet service, since data traffic is biased in the forward direction (terminal to base station) rather than in the reverse direction (terminal to terminal), two different frequency channels spaced apart at regular intervals in the reverse and forward channels are used, respectively. Conventional CDMA / FDD (Frequency Division Duplex) schemes with the same frequency bandwidth have poor frequency utilization efficiency. To improve this, one CDMA / TDD (Time Division Duplex) method, which uses the same frequency channel as the reverse and forward channels, and uses the reverse and forward links in a time division manner, is one of the standard methods of the IMT-2000 system. It became.

Optical repeater is a device that is widely used to expand the service area of one base station, and converts the forward signal transmitted from the base station to the optical signal at the location close to the base station or converts the optical signal transmitted to the base station to the reverse signal. Slave optical that converts the optical signal from the master optical repeater to the forward high frequency signal and transmits it to the terminal or the reverse high frequency signal from the terminal to the master optical repeater at a location far from the base station to convert It consists of a repeater. In a conventional CDMA / FDD system, a high frequency transmission and reception path of a slave optical repeater is generally connected to one antenna using a duplexer or to a transmission and reception antenna without a duplexer, respectively. In the conventional CDMA / FDD system, since the reverse link and the forward link are distinguished by using different frequency bands having constant intervals, the reverse link and the forward link can be used by using a filter suitable for each band in the transmission and reception paths of the slave optical repeater. Interference between link signals could be eliminated.

However, in the CDMA / TDD system, since the occupied bands of the reverse link and the forward link signals are the same, even if a band filter is used, the high frequency signal output of the slave optical repeater flows into the receiver through the receiving antenna, thereby interfering with the forward signal and the reverse signal. This will happen. An object of the present invention is to devise an apparatus for eliminating interference between a forward signal and a reverse signal in a high frequency transmitter and receiver of a slave optical repeater used in a CDMA / TDD system. In particular, the slave optical repeater detects the forward signal and controls the variable path switch to block the path from the receiving antenna to the reverse link receiver to prevent the forward signal from entering the reverse receiving path.

Hereinafter, with reference to the accompanying drawings will be described in detail the technical field to which the present invention belongs.

1 is a diagram illustrating a state in which one frequency channel is used as a forward link and a reverse link by time division in a CDMA / TDD mobile communication system, and a base station performs a forward link or a reverse direction on a specific frequency channel for a time divided by a unit called a timeslot. Use only one of the links. In the example of FIG. 1, a base station designates a specific frequency channel as a reverse link (U) during a first timeslot period, a forward link (D) during a second and a third timeslot period, a reverse link (U) during a fourth timeslot period, and five. During the first timeslot, it is used as a forward link (D). Typically, one timeslot consists of short times of less than a few milliseconds.

2 is a general configuration of an optical relay system used in a CDMA system, the forward signal generated from the base station 10 is converted into an optical signal by the master optical repeater 20, and the slave optical repeater 30 through the optical cable 20a. The slave optical repeater 30 converts the optical signal from the master optical repeater 20 into a high frequency signal and transmits the signal to the terminal 40. The reverse signal generated from the terminal 40 is converted into an optical signal by the slave optical repeater 30 and transferred to the master optical repeater 20, and the master optical repeater 20 is an optical signal from the slave optical repeater 30. The signal is transferred to the base station 10 by converting the signal of the appropriate band. In this case, the appropriate band is determined by which point the master optical repeater 20 transmits the reverse signal to the base station receiver. In general, the appropriate band is often a medium frequency or a low frequency band rather than a high frequency used in a wireless environment. The present invention is applied regardless of the manner in which the base station 10 and the master optical repeater 20 are connected. The configuration of the optical relay system illustrated in FIG. 2 is mainly used for supplying a CDMA signal to a building having a poor radio wave environment, and the optical relay system according to the present invention can also be used in the same configuration as that of FIG.

3 is a general master optical repeater 20 for a CDMA mobile communication system. The master gain controller 101 adjusts the gain of the forward signal input from the base station 10 or the gain of the reverse signal generated from the terminal 40. ) And an optical transceiver 102 for converting a signal input from the master gain controller 101 into an optical signal, a MCU (Master Control Unit) 103 and a MCU (103) for controlling and supplying power to the above modules. ) Is a modulator 101a for transmitting and receiving data for monitoring and controlling the slave optical repeater 30. The master optical repeater 20 illustrated in FIG. 3 is located between the base station 10 and the slave optical repeater 30 and relays signals in respective directions as in the example of the optical repeater system of FIG. It can be used as the master optical repeater 20 of the optical relay system.

4 is a slave optical repeater 30 in a general CDMA / FDD mobile communication system, and converts an optical signal received from the master optical repeater 20 into a high frequency signal or converts a high frequency signal generated from the terminal 40 into a master optical repeater ( 20, an optical transceiver 201 converting an optical signal for transmission to the optical signal, a slave gain controller 202 for controlling the gain of the high frequency signal, an amplifier 203 for amplifying the high frequency signal to be transmitted to the terminal 40, and forward and reverse directions. Slaves the reverse signal received from the duplexer 204 for separating the high frequency signal of the link, the forward band filter 204a constituting the duplexer 204, the reverse band filter 204b, the antenna 205, and the terminal 40. A receiver 206 for transmitting to the gain controller 202, a slave control unit (SCU) 207 in communication with the MCU 103 of the master optical repeater 20 and controlling each module of the slave optical repeater 30. ), PSU (Power Supply Unit) 208 for supplying power to each module of slave optical repeater 30, SCU 207 receives control data from MCU 103, or a modulator for transferring status data ( 202a).

The optical relay system of the conventional CDMA / FDD system employing the slave optical repeater 30 illustrated in FIG. 4 relays a signal between the base station 10 and the terminal 40 in the following manner. The forward signal is transmitted from the base station 10 to the master gain controller 101 of the master optical repeater 20, and the gain is adjusted, and then converted into an optical signal in the optical transceiver 102 of the master optical repeater 20, thereby converting the optical cable 20a. Is transmitted to the optical transceiver 201 of the slave optical repeater 30 and converted into a high frequency signal, and then the gain is adjusted in the slave gain controller 202, amplified in the amplifier 203, and the forward band filter 204a. Passed through to the antenna 205 is radiated. The reverse high frequency signal generated by the terminal 40 is received by the antenna 205 and passed through the reverse band filter 204b, the band is cleared, and then transmitted to the slave gain controller 202 through the receiver 206 to gain. This is adjusted and converted into an optical signal in the optical transceiver 201 of the slave optical repeater 30 and transmitted to the optical transmitter 102 of the master optical repeater 20 through the optical cable 20a, and then into a signal of an appropriate frequency band. Is converted and passed to the master gain controller 101. The gain-adjusted signal in the master gain controller 101 is transmitted to a receiver (not shown) of the reverse link of the base station 10.

The present invention relates to a slave optical repeater (30) in the construction of an optical relay system of a CDMA mobile communication system as illustrated in FIG. 2, in particular, the conventional technique used for the CDMA / FDD system illustrated in FIG. This is a technique for improving the slave optical repeater 30 can be used in the CDMA / TDD system of the future mobile communication system such as IMT-2000.

As described above, in the optical relay system of the CDMA / FDD system, the forward signal from the base station 10 and the reverse signal from the terminal 40 are eventually forward band filters 204a in the duplexer 204 of the slave repeater 30. And reverse band filter 204b. In other words, the CDMA / FDD system uses a frequency band in which the forward signal and the reverse signal are divided at regular intervals, so that the forward signal passing through the forward band filter 204a does not pass through the reverse band filter 204b, so that the forward signal There is no case where the reverse signal enters the receiver 206. However, in the CDMA / TDD system, since the forward signal and the reverse signal use the same frequency band, the forward band filter 204a and the reverse band filter (204) installed in the duplexer 204 of the conventional slave repeater 30 illustrated in FIG. 204b passes a signal of the same band, so that the forward signal is introduced into the receiver 206 of the reverse signal.

In this case, the relatively strong signal amplified by the amplifier 203 is introduced into the receiver 206 of the reverse signal, which causes damage to the system or significantly degrades the quality of the reverse signal. An object of the present invention is to devise a slave optical repeater 30 that normally operates in a CDMA / TDD system. In order to achieve the above object, the present invention provides a method for knowing a forward link and a reverse link usage state used by time division in a slave optical repeater 30 remote from a base station, and thereby a reverse receiver (when a forward signal is transmitted). The slave optical repeater 30 is characterized by a method of blocking the transmission of the signal to the 206.

FIG. 1 shows an example of using reverse and forward links operating in time division in a CDMA / TDD system.

2 is a general configuration of an optical relay system used in a CDMA system

3 is a general master optical repeater for a CDMA mobile communication system.

4 is a slave optical repeater in a general CDMA / FDD mobile communication system

5 is a slave optical repeater for a CDMA / TDD mobile communication system employing path switching by a signal sensor according to the present invention.

6 is a configuration example of a variable path switch used in the configuration of FIG. 5 of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: base station 20: master optical repeater

20a: optical cable

30: slave optical repeater 40: terminal

101: master gain controller 101a, 202a, 302a: modulator demodulator

102, 201, 301: Optical transceiver 103: MCU (Master Control Unit)

202, 302: slave gain controller 203, 304: amplifier

204: duplexer 204a, 305: forward band filter

205 and 306: antennas 204b and 305a: reverse band filter

207, 310: SCU (Slave Control Unit) 208, 311: PSU (Power Supply Unit)

303: distributor 307: sensor and switch control

308: variable path switch 206, 309: receiver

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and operation of the invention.

5 is a slave optical repeater 30 for a CDMA / TDD mobile communication system adopting a path switching by a signal sensor according to the present invention, and converts an optical signal received from the master optical repeater 20 into a high frequency signal or a terminal ( An optical transceiver 301 for converting a high frequency signal generated from 40 into an optical signal for transmission to the master optical repeater 20, a slave gain controller 302 for controlling gain of a high frequency signal, and a forward signal for an amplifier 304. And a divider 303 distributed to the sensor and the switch controller 307, a forward band filter 305 for noise cancellation of the forward signal, a variable switch 308 for forward and reverse path selection, an antenna 306, a reverse signal A reverse band filter 305a for noise cancellation, a receiver 309 for transmitting the reverse signal received from the terminal 40 to the slave gain controller 302, and the MCU 103 of the master optical repeater 20; SCU (Slave Control Unit) 310 for communicating and controlling each module of the slave optical repeater 30, PSU (Power Supply Unit) 311 for supplying power to each module of the slave optical repeater 30, The SCU 310 consists of a modulator 302a for receiving control data from the MCU 103 or for conveying status data. In the above description, the variable path switch 308 is either the forward band filter 305 or the reverse band filter 305a of the antenna 306 and the slave optical repeater 30 under the control of the sensor and the switch controller 307. This switch configures the path to the bay.

FIG. 6 illustrates the variable path switch 308 used in the configuration of FIG. 5 of the present invention and is a switch constituting only one path of A-C or B-C at a time. That is, when the switch is closed to the A path, the path of A-C is formed and the path of B-C is blocked. On the other hand, when the switch is closed to the B path, only the B-C path is formed and the A-C path is blocked.

The slave optical repeater 30 illustrated in FIG. 5 according to the present invention functions as follows. The forward signal, which is converted into an optical signal in the optical transmitter 102 of the master optical repeater 20 and transferred to the optical transmitter 301 of the slave optical repeater 30 through the optical cable 20a, is converted into a high frequency signal and then slave gain. The gain is adjusted in the controller 302, distributed in the divider 303, and delivered to the amplifier 304, the sensor, and the switch controller 307. The signal delivered to the amplifier 304 is amplified and passed through the forward band filter 305. At this time, when the sensor and the sensor of the switch control unit 307 detects a case where the intensity of the signal transmitted through the distributor 303 is above a certain level (for example, the background noise level), the variable path switch 308 is controlled to control the receiver ( The path in the direction of 309 is cut off, and only the path in the direction of the amplifier 304 is configured. Accordingly, the forward signal passing through the forward band filter 305 is radiated through the antenna 306 via the variable path switch 308 without entering the reverse receiver 309. On the other hand, if the sensor of the sensor and the switch control unit 307 does not detect a signal higher than a certain level (for example, the background noise level) by controlling the variable path switch 308 to disconnect the path in the direction of the amplifier 304, the receiver Only the path in the 309 direction is constituted. At this time, the reverse high frequency signal generated by the terminal 40 is received by the antenna 306 and passed through the reverse band filter 305a and the band is cleared, and then to the slave gain controller 302 through the receiver 309. The gain is adjusted to be adjusted and converted into an optical signal in the optical receiver 301 of the slave optical repeater 30 is transmitted to the optical receiver 102 of the master optical repeater 20 through the optical cable 20a.

For reference, the detection of the forward signal for the control of the variable path switch 308 of the slave optical repeater 30 according to the present invention can be performed even without the sensor of the distributor 303 and the sensor and the switch controller 307. For example, the presence or absence of the forward signal may be detected based on the gain value of the forward signal detected by the slave gain controller 302 of the slave optical repeater 30.

As described above, the slave optical repeater for the CDMA / TDD mobile communication system adopting the path switching by the signal sensor according to the present invention uses the slave optical repeater for the CDMA / FDD system as the slave optical repeater for the CDMA / TDD system. When the forward signal generated when the system is damaged or the signal quality is deteriorated due to inflow to the reverse receiver, the forward signal is detected through the sensor and the variable path switch 308 is controlled to the reverse link receiver 309 direction. There is an effect to improve by breaking the path of. In addition, the slave optical repeater for the CDMA / TDD system according to the present invention detects the forward signal by itself to form a transmission and reception link, so that the base station and the slave optical repeater can operate independently without being notified separately of the forward and reverse link states from the base station. There is an effect that can reduce the cost incurred due to signal transmission between the liver.

Claims (5)

And a method of detecting a forward signal to block a path between an antenna (306) and a receiver (309). The method of claim 1, wherein the distributor (303) and a sensor are used. The method of claim 1, wherein the slave signal controller (30) of the slave optical repeater (30) is used as a reference to the gain value of the forward signal sensed. Detecting the presence or absence of the forward signal and variably setting only one of the paths between the antenna 306 and the receiver 309 or between the antenna 306 and the amplifier 304 according to the result. Optical relay system for CDMA / TDD mobile communication system The method of claim 4, wherein the distributor (303), the sensor and the switch control unit (307), and the variable path switch (308) are used.