KR100588325B1 - Method and device for attaining synchronization from base station signals in time division duplex system - Google Patents

Abstract

A method and apparatus for obtaining transmission and reception switching synchronization from a base station signal in a time division duplex system are disclosed. A feature of the method and apparatus of the present invention is to use a signal transmitted from a base station to obtain synchronization between the base station and a remote device, including a repeater, without using a GPS signal. In addition, according to the method and apparatus of the present invention, the duty and period of the base station transmission signal and the duty of the terminal signal are detected to check whether synchronization is correct.

In the present invention, the process of acquiring synchronization includes reception of a base station signal, level detection, correlation, acquisition of synchronization, and generation of a switching signal.

Time Division Duplication, TDD, Synchronous, Switching, Repeater, Base Station, Remote Equipment

Description

Method and device for acquiring transmission and reception switching synchronization from base station signal in time division duplex system {Method and device for attaining synchronization from base station signals in time division duplex system}

1 is a block diagram of a repeater for transmitting and receiving synchronization using a conventional GPS.

2 is a block diagram of a repeater including a transmission and reception synchronization acquisition and synchronization check apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of power detection, switching signal detection, switching control, and an inspection block of FIG. 2.

4 illustrates level detection and an analog signal to digital signal converter.

5 is a diagram illustrating a process of extracting a base station output time from a repeater input signal.

6 is a diagram illustrating a wireless network of a TDD system.

7 is a conceptual diagram of RF transmission and reception in a repeater of a TDD system.

8 is a diagram illustrating a forward / reverse output when a repeater performs normal RF transmission / reception switching.

9 is a diagram illustrating a forward / reverse output when abnormal RF transmission / reception switching is performed in a repeater.

The present invention relates to a method and apparatus for obtaining transmission and reception switching synchronization from a base station signal in a time division duplex (TDD) system. Particularly, the present invention relates to a base station and a relay period RF transmission / reception using a signal input from a forward input port of a repeater. A method and apparatus for obtaining and checking a switching synchronization.

One of the conventional RF and transceiver switching synchronization schemes discussed in the related art is using a GPS receiver. Since all base stations use GPS to synchronize the RF transmission / reception switching between the base stations, the base station and the relay period can be used to perform the RF transmission / reception switching synchronization with the base station.

1 is a block diagram showing a structure of a repeater for performing switching synchronization using a conventional GPS. This is a reflection of the concept of the RF transmission and reception switching synchronization between the base station, it can be seen that the switching synchronization between the base station and the remote equipment (including the repeater) is also performed accurately. In FIG. 1, the directional antenna 1 positioned in the direction of the base station and the antenna 14 in the terminal direction are connected to the repeater through coaxial cables 2 and 13. The GPS receiver 27 receives the GPS signal transmitted from the satellite using the GPS antenna 25 and generates a switching synchronization signal used by the base station. This switching synchronization controls the RF switches 3 and 12 for synchronization of transmission and reception.

The forward signal transmitted from the base station is received by the antenna 1 and connected to the repeater via the coaxial cable 2. In general, in the RF repeater, the antenna 1 is installed outdoors and is oriented toward the base station. When the forward signal of the base station is input, the RF switch 3 is in the forward input state according to the RF transmission and reception synchronization signal. The forward input signal passes through the filter 4 via the RF switch 3. The forward signal passing through the filter (4) is a low noise amplifier (5), an attenuator (6) for forward automatic gain control (AGC), a frequency converter (7), an IF SAW filter (8), a frequency converter (9), an RF amplifier. 10, the filter 11, the RF switch 12, the coaxial cable 13, and the antenna 14 are transmitted to the terminal. Here, in the conventional FDD scheme, since downlink and uplink frequencies are separated and operate simultaneously in time, when the forward AGC is to be performed using the attenuator 6, after measuring downlink output from the repeater The attenuator is controlled to output a constant downlink, and the same control is applied to the attenuator in the uplink as the downlink attenuator control.

The reverse signal transmitted from the terminal is received by the antenna 14 and connected to the repeater through the coaxial cable 13. In general, the antenna 14 in the RF repeater is installed indoors. When the reverse signal is input to the repeater, the RF switch 12 is in the reverse input state according to the RF transmit / receive synchronization signal. The reverse input signal passes through filter 23 via RF switch 12. The reverse signal past filter 23 is a low noise amplifier 22, frequency converter 21, IF SAW filter 20, attenuator 19 for reverse Automatic Level Control (ALC), frequency converter 18, RF amplifier. (17), filter 16, RF switch 3, coaxial cable 2, and antenna 1 are transmitted to the base station.

The repeater performing transmission and reception synchronization using the conventional GPS signal cannot be installed indoors because the GPS antenna 25 receives a signal from the satellite, and installation cost and maintenance cost are added because it must be installed outdoors. In addition, additional equipment of the antenna 25, the cable 26, and the GPS receiver 27 is required to perform the RF transmission / reception switching synchronization, thereby increasing the repeater price. In addition, although the RF transmission and reception switching synchronization is performed in the same manner as the base station, there is a problem that an error due to propagation delay may occur.

In order to solve the above problems, the present invention obtains an RF transmission and reception switching synchronization signal from an RF signal transmitted from a base station without using GPS, and a method and apparatus for checking an RF transmission and reception switching synchronization signal using a forward / reverse signal. To provide.

The method of the present invention for solving the above technical problem, the step of receiving a signal transmitted from a base station through an antenna, a level detection step of detecting only a voltage signal within a predetermined voltage range of the received signal, the level detected analog Converting the signal into a digital signal, correlating the digitally converted signal with a self-generated clock signal, and generating a switching signal by obtaining synchronization from a value obtained through the correlation. Meanwhile, the method may further include checking the synchronization signal by checking the duty and periodicity of the signal transmitted from the base station, and may check the duty of the terminal output signal in the synchronization check.

An apparatus of the present invention for solving the above technical problems is a level detection device for level detection of signals received at a base station and a terminal, an analog-to-digital converter for converting the level detected analog signal into a digital signal, of the transmission at the base station A clock generator for generating its own clock based on duty and periodicity, a correlator for correlating the digitally converted signal with the clock signal itself, and a transmit / receive switching signal generator for generating synchronization transmission / reception switching signals from values obtained by the correlator. It is composed. Meanwhile, the apparatus may further include a transmission / reception switching checker for inspecting a transmission / reception switching signal, and a control signal to an attenuator used to adjust a level of a signal transmitted from a base station, that is, a downlink signal, when the level detection device detects a level. Gain control can be applied.

Hereinafter, a method and apparatus for transmitting and receiving switching synchronization between a repeater and a base station in a time division duplex system according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a repeater using a transmission and reception switching synchronization device according to an embodiment of the present invention. Referring to FIG. 2, the forward signal transmitted from the base station is received by the antenna 1 and connected to the repeater through the coaxial cable 2. In general, in the RF repeater, the antenna 1 is installed outdoors and is oriented toward the base station. When the forward signal of the base station is input, the RF switch 3 is in the forward input state according to the RF transmission and reception synchronization signal. The forward input signal passes through the filter 4 via the RF switch 3. The forward signal passing through the filter (4) is a low noise amplifier (5), attenuator (6) for receiving manual control or external control signals for forward AGC (automatic gain control) and changing its resistance value, frequency converter (7). Terminal via IF SAW filter (8), frequency converter (9), RF amplifier (10), filter (11), RF coupler (12), RF switch (13), coaxial cable (14), antenna (15) Is sent.

The reverse signal transmitted from the terminal is received by the antenna 15 and connected to the repeater through the coaxial cable 14. In general, the antenna 15 in the RF repeater is installed indoors. When the reverse signal is input to the repeater, the RF switch 12 is in the reverse input state according to the RF transmit / receive synchronization signal. The reverse input signal passes through filter 26 via RF switch 13. The reverse signal past the filter 26 is a low noise amplifier 25, a frequency converter 24, an IF SAW filter 23, an attenuator 22 for reverse automatic level control (ALC), a frequency converter 21, an RF amplifier. 20, the filter 19, the RF coupler 18, the RF switch 3, the coaxial cable 2, and the antenna 1 is transmitted to the base station.

The power detection, switching signal detection, switching control and inspection block 17 detects power using the RF coupler 12 from a signal input to the forward input port of the repeater, and then extracts a switching signal to control the RF transmission / reception switch. do. In addition, the RF coupler (12, 18) detects the forward signal and the reverse signal to check whether the normal switching. 3 is a block diagram showing the configuration of the power detection, switching signal detection, switching control and inspection block 17 in more detail. In FIG. 3, the forward output / reverse output is the RF signal received at the RF coupler 12, 18 of FIG. 2. In FIG. 3, the RF transmission / reception switching clock is a switching clock signal for controlling the RF switches 3 and 13 of FIG. 2. In FIG. 3, the level detection and analog signal-to-digital signal converters 101 and 102 convert an RF signal into an analog voltage using a detector in a forward / reverse signal, and a voltage of a predetermined voltage range (configurable) &Quot; 1 " and other voltages are determined to be " 0 " and input to the correlator 103 or the RF transceiver switching checker 105. In addition, although not separately illustrated in FIG. 3, the power detection, switching signal detection, switching control and inspection block 17 of FIG. 2 may set its own clock based on the duty and periodicity of the signal transmitted from the base station as described above. A clock generator for generating is further provided. In addition, in the TDD scheme according to the present invention, since the frequency is the same and is divided into a downlink frame and an uplink frame only in time, when the output of the first frame of the downlink (frame 0) is measured, the next uplink Since the first frame is continued, the control point of the downlink output is applied from the second frame of the downlink (called frame 1) following the first frame of the uplink. Similarly, in uplink, uplink frame 1 following downlink frame 1 is controlled.

4 is a circuit diagram illustrating level detection and an analog signal-to-digital signal converter. In FIG. 4, 201 detects an RF signal and outputs it to analog DC, and voltage sources 202 and 206 are used to control digital ranges of "1" and "0". The comparator 203 and 207, the diodes 204 and 208, the inverter 205 and the like are also constituted. In FIG. 4, when the voltages of the voltage sources 202 and 206 are adjusted, the RF signal of the desired input range is determined as " 1 " and the remaining signals are output as " 0 ". The digital stream signal thus output is input to the correlator or the RF transceiving switching tester. In the correlator, synchronization is obtained from a correlation value obtained by correlating a digital stream signal converted from an RF signal into a digital signal and a clock signal generated in a certain period. Here, the clock signal generated by itself is generated based on the duty, period, and guard time of the forward / reverse signal set in the base station.

5 shows a process of extracting the base station output time from the repeater input signal. 5 (1) shows the RF signal input to the repeater forward input port. 5 (2) shows a digital waveform obtained by detecting an RF signal input to a forward input port and detecting the level. Since most base station transmission signals are constantly received, when the level range is detected, most of them are determined to be "1". However, since the output signal of the adjacent terminals is always changed, most of them are determined to be "0" and sometimes "1". May be determined. 5 (3) is a digital clock signal generated inside the repeater, so the duty, cycle, and guard time of the base station RF transmission signal are known, so that it is possible to generate a digital waveform as shown in FIG. 5 (3). Do. In the correlator, the digital signal of FIG. 5 (3) is correlated with the signal of FIG. 5 (2) for a predetermined time, while the signal of FIG. 5 (3) is shifted. Then, a waveform as shown in FIG. 5 (4) can be obtained. 5 (4) shows a correlation value, the base station output time can be known on the basis of when the correlation value is the highest value, thereby obtaining the RF transmission and reception switching synchronization.

In FIG. 3, the RF transmission / reception switching signal generator 104 generates a switching signal required for the RF switch with a timing point obtained by synchronizing with the correlator 103. The RF transmission / reception switching signal generator 104 performs three-step state control that does not amplify both forward signal amplification, reverse signal amplification, and forward / reverse direction. In FIG. 3, the RF transmission / reception switching checker 105 checks whether the repeater is performing normal switching during operation. The RF transmit / receive switching check is performed using only the forward output or both forward and reverse outputs. The RF transmit / receive switching check consists of the duty of the forward signal, i.e. the ratio of the ON time and OFF time of the digital signal, and the period, i.e. the time from the start of one pulse to the start of the next pulse and the duty of the reverse signal ( Duty). In the reverse case, however, it is performed when necessary.

6 is a diagram illustrating a wireless network of a TDD system. The signal transmitted from the base station is supplied to the terminal, and the signal received from the base station is amplified by the RF repeater for the shadow area such as the underground area and retransmitted to the terminal of the shadow area. The signal transmitted from the terminal in the shaded area reaches the base station receiver through the repeater. Since it is a TDD system, the signal received by the forward antenna at the repeater input is input with a time difference between the signal transmitted from the base station and the signal transmitted from the proximity terminal. The repeater antennas facing the base station are generally highly directional and are directed towards the base station and thus have a high signal level. In addition, almost constant level is always input since fading interference due to multipath is not greatly increased over time. The proximity terminal signal transmitted in the vicinity of the repeater has the characteristics of a random period and a random level. When a signal obtained by combining the base station transmission signal and the neighboring terminal output signal is input to the repeater, the base station transmission signal timing is extracted using a constant level of radio propagation characteristics received from the base station, and the timing is used to synchronize the repeater RF transmission and reception switching. Will be obtained.

7 illustrates the concept of the RF transmission and reception switching synchronization in the repeater. 7) shows a waveform transmitted from the base station. Guard time represents the time interval between the forward and reverse signals. Here, the arrows indicate the transmit-receive switching and the receive-transmit switching time, and perform switching in succession alternately. Fig. 7 2) shows the relay output in time when the RF switch 3 in Fig. 2 is in the forward receiving state. When the RF switch 3 of FIG. 2 is in the forward receiving state, the signal received by the repeater antenna 1 of FIG. 2 is a base station transmission signal and neighboring terminal output signals. The base station transmission signal shown in 2) of FIG. 7 is a signal from which the signal transmitted from the base station is propagated and delayed. Here, the time difference between the base station transmission signal and the adjacent terminal output signal is almost equal to the guard time. 7 is a clock signal reproduced by extracting the timing of the base station output signal from the signal from which the base station output signal and the neighboring terminal output signal are input and correlated with the internal signal of the repeater. This correlation concept takes advantage of the fact that when a base station transmit signal is input to a repeater at a certain level range, the nature of the duty and period of the base station transmit signal. 7) of FIG. 7 is an RF transmission / reception switching signal using a clock detected from the forward signal of FIG. 7). The dead time is set when RF transmission / reception switching is performed so that the repeater does not amplify the RF transmission / reception, because it prevents the oscillator from oscillating due to the response of the RF switch when performing the RF transmission / reception switching in the relay, It is to remove RF signals that are not in timing. 5 of FIG. 7 illustrates an output signal transmitted by the terminal receiving the forward output signal from the repeater in accordance with the transmission and reception timing. 7 shows a signal in which the output signal of the terminal reaches the base station by radio wave propagation through the repeater, and the terminal output arrives at the base station due to the repeater time delay and the propagation time delay in the radio. When the RF transmission and reception switching synchronization is obtained, the repeater performs normal RF transmission and reception switching switching, and the RF transmission and reception switching checker 105 of FIG. 3 checks whether the RF transmission and reception switching of the repeater is normally performed.

8 shows the forward / reverse output when the repeater normally performs RF transmission / reception switching. 8 shows a base station transmission output, and FIG. 8 shows a signal for controlling the RF switch in the switching generator during RF transmission after acquiring the RF transmission / reception switching synchronization. 3) of FIG. 8 shows the repeater forward output when the repeater switching is normally performed. 8, 4) shows the output signal of the terminal in the repeater coverage (Cover), 5) of FIG. 8 shows the repeater reverse output.

9 shows a signal when abnormal RF transmission / reception switching is performed in a repeater. In FIG. 9, due to the abnormal switching control, the duty of the forward and reverse signals is changed. The RF transmit / receive switching checker 105 of FIG. 3 may detect an abnormal state from the changing duty.

Acquisition of synchronization is very important in a time division duplex (TDD) system. According to the present invention, RF transmission / reception switching synchronization can be performed inexpensively using simple hardware and algorithms in a remote device including a repeater requiring synchronization with a base station. You can get it. Accordingly, the service using the repeater is activated in the time division redundancy system, and the system construction cost and the quality of the service can be greatly improved in the service of the shadow area such as the underground shopping store and the subway.

Claims (7)

delete delete delete In the method for obtaining the switching synchronization using a signal input to the repeater, Receiving a signal transmitted from a base station via an antenna; A level detection step of detecting an envelope by a detector and converting the received signal into an analog signal; Detecting only the voltage signal within a predetermined voltage range and converting the level-detected analog signal into a digital signal; Generating a self-clock based on the duty and periodicity of the signal transmitted from the base station and correlating the digitally converted signal with the self-generated clock signal; Generating a switching signal by acquiring synchronization from the value obtained through the correlation, but having a dead time between the forward and reverse signals of the generated switching signal and not amplifying transmission and reception; And Checking the synchronization signal by checking the duty and period of the signal transmitted from the base station and the duty and period of the switching synchronization signal generated by synchronizing with the repeater; and transmitting and receiving switching synchronization from the base station signal in a time division duplex system. How to obtain. delete delete Level detection of the signals received from the base station and the terminal, and control the attenuator to output a constant downlink after measuring the output of the downlink at the repeater during the level detection, and also to the attenuator in the uplink by the control of the downlink attenuator A level detection device for controlling a downlink gain of the repeater by transmitting a control signal to an attenuator used for processing a signal transmitted from a base station to perform the same control; An analog-digital converter for converting the level detected analog signal into a digital signal; A clock generator that generates its own clock based on the duty and periodicity of the signal transmitted from the base station; A correlator for correlating the digitally converted signal with a self-generated clock signal; A transmission / reception switching signal generator which acquires synchronization from the value obtained by the correlator and generates a transmission / reception switching signal; And Transmission and reception switching checker for checking the synchronization signal by checking the duty and period of the switching synchronization signal generated by synchronizing the base station signal and the duty and period of the base station signal; Apparatus for acquiring transmission and reception switching synchronization from the base station signal in a time division duplex system .

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