KR101065456B1 - On-Channel repeater and repeating METHOD thereof - Google Patents

Abstract

The present invention relates to a relay apparatus and a relay method thereof, by using a reference signal in the relay apparatus to remove a feedback signal received from a reception antenna, thereby increasing the output of a signal retransmitted through the transmission antenna. It can extend the area of delivery and reduce the cost of network construction.

In addition, the present invention can improve the quality of the received signal by estimating the distortion of the signal by estimating the channel of the received signal from which the feedback signal has been removed.

Relay, Feedback Signal, Symbol, Channel, Estimation, Echo Cancellation

Description

Relay device and relay method thereof {On-Channel repeater and repeating METHOD about}

The present invention relates to a relay apparatus and a relay method thereof, and a relay apparatus and a relay method for removing the feedback signal and compensating for the distortion of the signal.

The present invention is derived from the research conducted as part of the IT growth engine technology development project of the Ministry of Information and Communication and the Ministry of Information and Telecommunications Research and Development. [Task Management No .: 2007-S-006-01] RF relay technology development].

In general, the main transmitter and repeater are arranged in accordance with the surrounding terrain, features and service area. The repeater is installed in the area where the signal of the main transmitter is weakly received, thereby eliminating anxiety and widening the transmission range of the main transmitter signal.

1 is a diagram illustrating a service using an existing co-channel repeater.

As shown in Fig. 1, each repeater relays the same frequency signal. That is, the main transmitter 10 transmits a signal through the transmission frequency A, and each of the repeaters 21 to 24 (hereinafter, referred to as a “co-channel repeater”) transmits the signal at the same frequency as the transmission frequency A. Relay. In order to enable such a service, signals transmitted from the main transmitter 10 and the co-channel repeaters 21 to 24 should be identical to each other and have a small time delay.

2 is a diagram illustrating a conceptual diagram of an existing co-channel repeater.

As shown in FIG. 2, the conventional co-channel repeaters 21 to 24 may remove the feedback signal to prevent the retransmitted signal from being received and amplified again by the receiving antennas of the co-channel repeaters 21 to 24. Can be used an echo canceller.

However, since the signal received from the main transmitter is received in a multi-path, when distortion occurs in the received signal, the co-channel repeaters 21 to 24 amplify and retransmit the distorted feedback signal so that the quality of the signal does not improve. have.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a relay apparatus and a relay method capable of improving signal quality of a transmission and reception signal by compensating for signal distortion of a reception signal input from a main transmitter and removing feedback signals.

According to an aspect of the present invention, a receiver for receiving a first received signal from the outside and down-converting the second received signal, receiving a first reference signal from the inside, and down-converting it to a second reference signal, the second reference signal And an echo converter which down-converts the second received signal into a third reference signal and a third received signal, respectively, and outputs a fourth received signal by removing a feedback signal from the third received signal using the third reference signal. A demodulator for demodulating at least one frame from the fourth received signal and extracting a symbol from the demodulated frame, estimating a channel using the symbol, and using the information of the estimated channel to determine the fourth received signal. Provided is a repeater comprising an equalizer for outputting a fifth received signal by compensating for channel distortion, and a transmitter for transmitting the fifth received signal.

According to another feature of the present invention, there is provided a signal relay method of a relay device. The relaying method may include receiving a first received signal from an external source and down converting the second received signal into a second received signal, receiving a first reference signal coupled to an output terminal of the relay device, and converting the second reference signal into a second reference signal; Down-converting the second reference signal and the second received signal into a third reference signal and a third received signal, respectively, and removing a feedback signal from the third received signal by using the third reference signal to receive a fourth signal Outputting a signal; demodulating at least one frame from the fourth received signal; extracting a symbol from a demodulated frame; estimating a channel using the symbol; and using the estimated channel information Compensating for the channel distortion of the received signal to output the fifth received signal, and transmitting the fifth received signal.

According to an exemplary embodiment of the present invention, by removing a feedback signal from a received signal received through a receive antenna using a reference signal, the output of a signal retransmitted through the transmit antenna can be increased, thereby widening a signal transmission area. You can save money.

In addition, by estimating the channel of the received signal from which the feedback signal is removed, the distortion of the signal may be compensated, thereby improving the quality of the received signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “module”, etc. described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software. have.

Now, a relay device and a relay method thereof according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the embodiment of the present invention, a co-channel relay apparatus for receiving a signal of frequency A from a main transmitter and retransmitting a signal of frequency A will be described. At this time, in the embodiment of the present invention, the transmission signal of the main transmitter received by the reception antenna of the same channel relay apparatus is called a "receive signal", and the signal transmitted from the same channel relay apparatus to the transmission antenna is called "transmission signal". At this time, a signal received by the receiving antenna again among the transmission signals transmitted through the transmitting antenna of the same channel relay apparatus is referred to as a "feedback signal".

In the embodiment of the present invention, terrestrial digital multimedia broadcasting (T-DMB) is described as an example, but the relay apparatus and the relay method thereof according to the present invention can be applied to other broadcasting systems or communication systems.

3 is a block diagram of a relay apparatus according to an embodiment of the present invention.

As shown in FIG. 3, the receiver 100 includes an echo canceller 200, a demodulator 300, an equalizer 400, and a transmitter 500.

The receiving antenna receives the reception signal and the feedback signal and outputs the reception signal and the feedback signal as one RF (Radio Frequency) reception signal.

The receiver 100 down-converts an RF received signal into an intermediate frequency (IF) signal. In addition, the receiver 100 down-converts the reference signal coupled to the output terminal of the transmitter 500 into a reference IF signal. The reference signal is a signal coupled to the output terminal of the transmitter 500 and is used to remove the feedback signal from the signal input through the receiving antenna.

The echo canceller 200 removes the feedback signal from the IF received signal by using the reference IF signal.

The demodulator 300 demodulates a T-DMB frame from the IF signal from which the feedback signal is removed, and extracts a phase reference symbol (PRS), which is the first Orthogonal Frequency Division Multiplexing (OFDM) symbol among the T-DMB frames. And output to the equalizer 400.

The equalizer 400 estimates a channel by using the PRS and updates a coefficient of a filter capable of compensating for the distortion of the channel to compensate for the distortion of the IF signal from which the feedback signal is removed.

The transmitter 500 converts the received signal of the equalizer 400 into an analog signal, up-converts the frequency, and transmits the received signal as an RF signal.

4 is a block diagram of the receiver 100 of the relay apparatus according to the embodiment of the present invention.

As shown in FIG. 4, the receiver 100 includes a first receiver 110 and a second receiver 120.

The first receiver 110 adjusts the local oscillator (OSC) to convert the RF reference signal into an IF reference signal.

The second receiver 120 adjusts the local oscillator (OSC) to convert the RF received signal into an IF received signal.

Each of the receivers 110 and 120 downgrades the band pass filter 111 and 121 for filtering one VHF channel, the low noise amplifiers 112 and 122 for amplifying the weak signal, and the RF frequency down to the IF frequency. RF down converters 113 and 123 for converting, band pass filters 114 and 124 for filtering one T-DMB signal, and automatic gain controllers 115 and 125 for maintaining the intensity of the received signal at a constant level. Include.

At this time, the method of adjusting the local oscillator of the RF down converters 113 and 123 to make the RF frequency 71.68Mhz as the IF frequency includes the method of maintaining the frequency spectrum normally (Normal) and the method of inverting the frequency spectrum up and down (inverted). have.

In the present invention, in order to avoid the phenomenon in which the harmonic component of the local oscillator (OSC) remains in the RF frequency band, an inverted frequency spectrum is used.

5A is a diagram illustrating a frequency spectrum of an RF signal input to a receiver according to an exemplary embodiment of the present invention, and FIG. 5B is a diagram illustrating a frequency spectrum of an IF signal output from a receiver according to an exemplary embodiment of the present invention.

When the range of the RF frequency is the band III (174 ~ 240Mhz) band, the spectrum of the RF received signal input to the receiver 100 is as shown in Figure 5a. At this time, the A signal is a signal input to the RF down converter (113, 123), the signal indicated by the dotted line is an image of the A signal.

When the signal having the spectrum as shown in FIG. 5A is input to the RF down converters 113 and 123, the oscillator is oscillated by the local oscillators 245.68 to 311.68Mhz and outputs the signal in the spectrum as shown in FIG. 5B. The signal B and the image inputted as output signals of the RF down converters 113 and 123 are inversely converted. In other words, the frequency spectrum of the A signal is inverted.

6 is a block diagram of the echo canceller 200 of the relay apparatus according to the embodiment of the present invention. 7A is a diagram illustrating a frequency spectrum of a signal output from an analog / digital converter of the echo canceller 200 according to an exemplary embodiment of the present invention, and FIG. 7B is a diagram of the echo canceller 200 according to an exemplary embodiment of the present invention. It is a figure which shows the frequency spectrum of the signal after mixing.

As shown in FIG. 6, the echo canceller 200 includes first and second analog / digital converters 210 and 220, and first and second numerically controlled oscillators NCO (NCO). 230 and 240, first and second low pass filters (LPFs) 250 and 260, feedback channel estimators 270, and second adaptive filters 280. ) And an Auto Level Controller (290).

The first A / D converter 210 converts an analog IF input signal into a digital reference signal using a sampling frequency (81.92Mhz).

The second A / D converter 220 converts an analog IF input signal into a digital received signal using a sampling frequency (81.92Mhz).

In this case, the digital signals output from the first and second A / D converters 210 and 220 are the C signals of FIG. 7A.

The first numerically controlled oscillator 230 mixes the digital reference signal into a baseband reference signal such that the center frequency Fc becomes zero.

The second numerically controlled oscillator 240 mixes the digital received signal into a baseband received signal such that the center frequency Fc becomes zero.

Then, as shown in Fig. 7B, the C signal becomes a D signal with the center frequency shifted by -10.24 MHz.

The first LPF 250 downsamples the baseband reference signal to 1/40 to output a baseband reference signal having a center frequency of 0 and a sampling frequency of 2.048Mhz.

The second LPF 260 downsamples the baseband received signal to 1/40 and outputs a baseband received signal having a center frequency of 0 and a sampling frequency of 2.048Mhz.

The feedback channel estimator 270 generates a filter coefficient value for removing the feedback signal included in the baseband received signal using the baseband reference signal and the baseband received signal. The feedback channel estimator 270 transmits the filter coefficient value to the second adaptive filter 280.

The second adaptive filter 280 generates a signal for removing the feedback signal from the baseband received signal using the filter coefficient value input from the feedback channel estimator 270, and removes the feedback signal from the baseband received signal.

The automatic level controller 290 constantly amplifies the level of the baseband received signal from which the feedback signal is removed from the second adaptive filter.

8 is a block diagram of the T-DMB demodulator 300 of the relay apparatus according to the embodiment of the present invention.

As shown in FIG. 6, the T-DMB demodulator 300 includes a low pass filter (LPF) 310, a numerically controlled oscillator 320, and a T-DMB demodulator 330.

The low pass filter 310 up-samples the baseband received signal from which the feedback signal is removed to output a baseband received signal having a center frequency of 0 and a sampling frequency of 8.192Mhz.

The numerically controlled oscillator 320 mixes the baseband received signal such that the center frequency Fc is 2.048 Mhz. Then, a baseband received signal having a center frequency of 2.048 MHz and a sampling frequency of 8.192 MHz is input to the T-DMB demodulator 330.

The T-DMB demodulator 330 demodulates the T-DMB frame from the baseband received signal and extracts a phase reference symbol (PRS) from the T-DMB frame. The PRS is the first symbol of the OFDM symbols, and the PRS is transmitted to the equalizer 400.

9 is a block diagram of the equalizer 400 of the relay apparatus according to the embodiment of the present invention.

As shown in FIG. 9, the equalizer 400 includes a channel estimator 410, an inverse converter 420, and a first adaptive filter 430.

The channel estimator 410 estimates a channel by signal processing the PRS received from the T-DMB demodulator 300.

The inverse transformer 420 inversely transforms the channel information estimated by the channel estimator 410 to generate coefficients of the first adaptive filter 430.

The first adaptive filter 430 compensates for channel distortion of the baseband received signal from which the feedback signal output from the echo canceller 200 is removed according to the coefficient input from the inverse converter 420. In this case, the signal output from the first adaptive filter 430 is output to the transmitter 500.

10 is a block diagram of a transmitter 500 of a relay device according to an embodiment of the present invention. 11A is a diagram illustrating a frequency spectrum of a signal output from a low pass filter 510 of a transmitter according to an exemplary embodiment of the present invention, and FIG. 11B is an output of the numerically controlled oscillator 520 of a transmitter according to an exemplary embodiment of the present invention. 11C is a diagram illustrating a frequency spectrum of a signal to be output, and FIG. 11C is a diagram illustrating a frequency spectrum of a signal output from the digital-to-analog converter 530 of a transmitter according to an exemplary embodiment of the present invention. 2 is a diagram illustrating a frequency spectrum of a signal output from the RF up converter 540 of the transmitter.

As shown in FIG. 10, the transmitter 500 includes a low pass filter (LPF) 510, a numerically controlled oscillator 520, a digital-to-analog (D / A) converter 530, and an RF up converter. 540, a power amplifier 550, and a channel filter 560.

The low pass filter 510 up-samples the baseband received signal from which the feedback signal is removed and the channel distortion is compensated by 40 times to output a baseband received signal having a center frequency of 0 and a sampling frequency of 81.92Mhz. At this time, the output signal of the low pass filter 510 is the same as the D 'signal of Figure 11a.

The numerically controlled oscillator 520 mixes the baseband received signal such that the center frequency is 10.24 MHz to shift the baseband frequency as shown in C ′ of FIG. 11B.

The D / A converter 530 converts the baseband received signal into an analog IF received signal using a sampling frequency (81.92Mhz), and inverts the frequency spectrum like the B 'signal as shown in FIG. 11C. This is because the RF up converter 540 uses an inverted method to invert the frequency in advance.

The RF up-converter 540 is oscillated by a local oscillator (245.68 ~ 311.68Mhz) and outputs an analog IF received signal as an RF signal, and uses an inverted method to generate an RF original signal as shown in the A 'signal of FIG. 11D. Output

The power amplifier 550 amplifies the output power of the RF original signal.

The channel filter 560 performs channel filtering on the amplified RF original signal and outputs the result to the transmitting antenna. In this case, the reference signal is a signal coupled to the output terminal of the channel filter 560.

As described above, in the embodiment of the present invention, by removing the feedback signal from the received signal received through the receiving antenna by using the reference signal, the output of the signal retransmitted through the transmitting antenna can be increased, thereby widening the signal transmission area. As a result, the cost of network configuration can be reduced. In addition, by estimating the channel of the received signal from which the feedback signal is removed, the distortion of the signal may be compensated, thereby improving the quality of the received signal.

The present invention may be implemented in hardware, software, or a combination thereof. In hardware implementation, an application specific integrated circuit (ASIC), a digital signal processing (DSP), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, and a microprocessor are designed to perform the above-described functions. May be implemented in other electronic units or combinations thereof.

In the software implementation, the module may be implemented as a module that performs the above-described function. The software may be stored in a memory unit and executed by a processor. The memory unit or processor may employ various means known to those skilled in the art.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a diagram illustrating a service using an existing co-channel repeater.

2 is a diagram illustrating a conceptual diagram of an existing co-channel repeater.

3 is a block diagram of a relay apparatus according to an embodiment of the present invention.

4 is a block diagram of a receiver of a relay apparatus according to an exemplary embodiment of the present invention.

5A is a diagram illustrating a frequency spectrum of an RF signal input to a receiver according to an exemplary embodiment of the present invention.

5B is a diagram illustrating a frequency spectrum of an IF signal output from a receiver according to an exemplary embodiment of the present invention.

6 is a block diagram of an echo canceller of a relay device according to an exemplary embodiment of the present invention.

7A is a diagram illustrating a frequency spectrum of a signal output from an analog / digital converter of an echo canceller according to an exemplary embodiment of the present invention.

7B is a diagram illustrating a frequency spectrum of a signal after mixing of an echo canceling unit according to an exemplary embodiment of the present invention.

8 is a block diagram of a T-DMB demodulator of a relay device according to an embodiment of the present invention.

9 is a block diagram of an equalizer of the relay apparatus according to the embodiment of the present invention.

10 is a block diagram of a transmitter of a relay apparatus according to an exemplary embodiment of the present invention.

11A illustrates a frequency spectrum of a signal output from a low pass filter of a transmitter according to an exemplary embodiment of the present invention.

11B is a diagram illustrating a frequency spectrum of a signal output from a numerically controlled oscillator of a transmitter according to an exemplary embodiment of the present invention.

11C is a diagram illustrating a frequency spectrum of a signal output from a digital / analog converter of a transmitter according to an exemplary embodiment of the present invention.

11D is a diagram illustrating a frequency spectrum of a signal output from an RF up converter of a transmitter according to an exemplary embodiment of the present invention.

Claims (11)

A receiver which receives the first received signal from the outside and down-converts the second received signal, and receives the first reference signal from the inside and down-converts the second received signal to the second reference signal; Down-converting the second reference signal and the second received signal into a baseband reference signal and a baseband received signal, respectively, and removing a feedback signal from the baseband received signal using the baseband reference signal to remove the fourth received signal; Echo canceller for outputting A demodulator for demodulating at least one frame from the fourth received signal and extracting a symbol from the demodulated frame; An equalizer for estimating a channel using the symbols and compensating for channel distortion of the fourth received signal using the estimated channel information to output a fifth received signal; and Transmitter for transmitting the fifth received signal Including; The first reference signal is a signal coupled to the output terminal of the transmitter Relay device. The method of claim 1, The receiving unit, A first down converter which down-converts the first received signal to generate the second received signal such that the frequency spectrum of the first received signal is inverted; and And a second down converter which down-converts the first reference signal to generate the second reference signal such that the frequency spectrum of the first reference signal is inverted. The method of claim 2, The echo removal unit, A feedback channel estimator for generating a filter coefficient value for removing a feedback signal included in the baseband received signal using the baseband reference signal and the baseband received signal, and And an adaptive filter for removing the feedback signal from the baseband received signal using the estimated filter coefficient value. The method of claim 1, The demodulation unit, A filter for low pass filtering the fourth received signal; A numerically controlled oscillator for shifting a center frequency of the low pass filtered fourth received signal; and And a demodulator for extracting the symbol from the fourth received signal shifted from the center frequency. The method of claim 1, The equalizing unit, A channel estimator for signal processing the symbol to estimate a channel, An inverse transformer for inversely transforming the estimated channel information to generate filter coefficients, and And an adaptive filter for compensating for channel distortion of the fourth received signal according to the filter coefficients. delete The method of claim 1, And the symbol is a phase reference symbol (PRS). In the signal relay method of the relay device, Receiving the first received signal from the outside and down converting the received second signal into a second received signal, Receiving a first reference signal coupled to an output terminal of the relay device and down converting the second reference signal to a second reference signal; Down converting the second reference signal and the second received signal into a baseband reference signal and a baseband received signal, respectively, Removing the feedback signal from the baseband received signal using the baseband reference signal and outputting the feedback signal as a fourth received signal; Demodulating at least one frame from the fourth received signal and extracting a symbol from the demodulated frame, Estimating a channel using the symbol, compensating for channel distortion of the fourth received signal using the estimated channel information, and outputting the channel distortion as a fifth received signal; and And transmitting the fifth received signal. The method of claim 8, The outputting of the fourth received signal may include: Estimating a filter coefficient value for removing the feedback signal from the baseband received signal using the baseband reference signal and the baseband received signal; and And removing the feedback signal from the baseband received signal using the estimated filter coefficient value. The method of claim 8, Extracting the symbol, Low pass filtering the fourth received signal; Shifting a center frequency of the low pass filtered fourth received signal; And extracting the symbol from the fourth received signal shifted from the center frequency. The method of claim 8, The outputting of the fifth received signal may include: Estimating a channel by signal processing the symbol; Generating filter coefficients by inversely transforming the estimated channel information; and Compensating for channel distortion of the fourth received signal according to the filter coefficients.

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