KR100780017B1 - Performance enhancement method of communication system by using PN code detecting and canceling and signal processing apparatus thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal processing apparatus of a wireless communication system. The present invention relates to a signal processing apparatus of a wireless communication system, and converts an RF signal received from a base station into a digital signal. The present invention relates to a method for improving communication quality by identifying and eliminating pseudonoise codes capable of transmitting a good signal by improving the signal quality, and a signal processing apparatus using the same.

As a signal processing apparatus of a wireless communication system according to the prior art, a repeater which receives an RF signal from a base station and retransmits it to a shaded area typically transmits by simply amplifying the received RF signal and converting a frequency of the received RF signal. A transmission method and a method of transmitting an RF signal received through a transmission medium such as an optical fiber are used.

However, these relays have a large number of unintended signals from other base stations or terminals, or signals transmitted to the transmitting antennas are fed back as well as signals of base stations to be retransmitted through the receiving antennas. There is a problem that becomes very poor.

The present invention is to solve the problems of the prior art as described above, the repeater converts the RF signal received from the base station to digital and then identifies the pseudo-noise code of the base station signal to be retransmitted by the digital signal processor and other The present invention provides a method for improving communication quality by removing signals and a signal processing device using the same.

Repeater, Pseudo Noise Code, Detection, Elimination, Digital, Signal Processing

Description

Performance enhancement method of communication system by using PN code detecting and canceling and signal processing apparatus

1 is a schematic diagram showing a base station environment in which a relay device is installed.

2 is a view showing a signal transmission and reception state of a general relay device.

3 is a block diagram of an interference cancellation system according to the prior art.

4 is a block diagram illustrating the use of a signal processing apparatus for improving communication quality by identifying and removing pseudonoise codes in accordance with the present invention.

5 is a block diagram illustrating the pseudonoise code identification and removal algorithm of FIG.

6 is a block diagram illustrating another embodiment of the pseudonoise code identification and removal algorithm of FIG.

7 is a diagram illustrating removal of a pseudo noise code of a relay device according to the prior art and the present invention;
8 and 9 are block diagrams of a relay apparatus using a signal processing apparatus for improving communication quality by identifying and removing pseudo-noise codes according to the present invention.

* Explanation of symbols for the main parts of the drawings

100. Repeater 101, 401. Receive Antenna                 

102, 415. Transmit antenna 103. Amplifier

104. Signal distribution means 105. Phase shifter

106. Attenuator 107. Delay line

108. Signal synthesizing means 301, 501. A / D converter

302. Digital signal processor 303, 503. D / A converter

402. Receive Band Filter 403. Low Noise Amplifier

404. First Mixer 405. SAW Filter

406. First Amplifier 407. First Attenuator

408. Oscillator 409. Second Amplifier

410. Low Pass Filter 411. Second Attenuator

412. Second Mixer 413. Power Amplifier

414. Transmission band filter 502, 502-1. First and second digital filter

504. PN detector 505. PN generator

506. Baseband Filter 507. PN Tracker

508. Subtractor 509, 509-1. First and second digital mixer

510, 510-1. Third and Fourth Digital Mixers 601. First Duplexer

602. First low noise amplifier 603. First power amplifier

604. Second duplexer 605. Second low noise amplifier

606. Second power amplifier 607. Transmission line

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal processing apparatus of a wireless communication system. The present invention relates to a signal processing apparatus of a wireless communication system, and converts an RF signal received from a base station into a digital signal. The present invention relates to a method for improving communication quality by identifying and eliminating pseudonoise codes capable of transmitting a good signal by improving the signal quality, and a signal processing apparatus using the same.

As a signal processing apparatus of a wireless communication system according to the prior art, a repeater which receives an RF signal from a base station and retransmits it to a shaded area typically transmits by simply amplifying the received RF signal and converting a frequency of the received RF signal. A transmission method and a method of transmitting an RF signal received through a transmission medium such as an optical fiber are used.

1 is a schematic diagram illustrating a base station environment in which a relay device is installed, and illustrates a case where a shadow area is generated in an existing service area (shown by a dotted line) of the base station 1 (BTS1) and retransmits a signal by the relay device (R). . In general, a cell-type mobile communication system is operated by a method in which a plurality of base stations covering a predetermined area are installed adjacent to each other to reuse an assigned channel frequency. That is, as shown in FIG. 1, base station 2 (BTS2) and base station 3 (BTS3) having respective service areas are adjacent to each other, and although not shown, a plurality of base stations are arranged to establish a communication network. .

FIG. 2 is a diagram illustrating a signal transmission and reception state of a general relay device. In FIG. 1, when a signal of base station 1 is retransmitted to a shadow area by using a relay device, FIG. 1 shows signals received at the receiving antenna 101 of the relay device. . As shown, the reception antenna 101 basically receives a signal f _B1 of the base station 1 to be retransmitted and _outputs a signal f _B1R retransmitted by the transmission antenna 102. In the reception antenna 101, the signals f _B1R retransmitted to the transmission antenna 102 together with the signals f _B2 , f _B3 ,... Of the other base stations are fed back and received.

Accordingly, as described above, in the relay apparatus according to the related art, in addition to the signal of the base station to be retransmitted through the receiving antenna, a plurality of unintended signals from other base stations or terminals are mixed or signals transmitted to the transmitting antenna are fed back. There is a problem that the communication quality is very poor due to the interference signal. That is, in addition to the signal (represented by a solid line) to be retransmitted as shown in FIG. 2, a number of unnecessary signals (indicated by a dotted line) are mixed.

In order to solve this problem, the interference cancellation system of FIG. 3 is disclosed. In the conventional interference cancellation system according to the related art, the RF signal received by the reception antenna 101 is amplified by the amplifier 103 and sent out through the transmission antenna 102, and the output signal of the amplifier 103 is signaled. After branching by the distribution means 104 to detect the amplitude and phase of the RF signal, a phase amplitude 105, an attenuator 106 and a delay line 107 generate signals of equal amplitude and antiphase and feed them back. By combining with the signal synthesizing means 108 to remove the interference signal.

However, the above-described method is difficult to obtain accurate dynamic amplitude and anti-phase signal due to the complicated system configuration. As a result, the interference efficiency of the interference signal is not reduced. There is another problem.

The present invention is to solve the problems of the prior art as described above, the repeater converts the RF signal received from the base station to digital and then identifies the pseudo-noise code of the base station signal to be retransmitted by the PN detector in the digital signal processor The purpose of the present invention is to provide a method for improving communication quality by removing other pseudonoise signals by a PN tracker and a signal processing device using the same.

In order to achieve the above object, the present invention provides an apparatus for processing and retransmitting a signal received from a base station or a communication system by a wired or wireless connection, comprising: first processing means for converting a received RF signal into an intermediate frequency; Converts the intermediate frequency, which is an analog signal, into a digital signal, downconverts the digital signal into a baseband digital signal, and then identifies a pseudo noise code of a base station signal to be retransmitted by a PN detector in a digital signal processor, Second processing means for generating the same PN as other pseudonoise signals, subtracting it, and removing the same to process DSP; Third processing means for up-converting the DSP-processed baseband digital signal and converting it back to an analog signal; And fourth processing means for converting the intermediate frequency converted into analog into an RF signal.

The first processing means includes: an apparatus for low noise amplifying an RF signal received from a base station; and an apparatus for bandpass filtering to remove signals other than a required band; and an apparatus for downconverting the RF signal to an intermediate frequency by a mixer. SAW filtering to remove noise components included in the intermediate frequency; and amplifying or attenuating the intermediate frequency signal to obtain a required gain.

The second processing means includes: an apparatus for converting the intermediate frequency signal into a digital signal by an A / D converter; and an apparatus for downconverting the digital signal into a baseband digital signal, and a PN detector from the baseband digital signal. And a DSP processing unit for identifying a pseudo noise code of a base station signal to be retransmitted, and generating a PN identical to other pseudo noise signals by a PN generator, subtracting it, and removing the same.

The third processing means includes an apparatus for up-converting the DSP-processed baseband digital signal into a digital signal, and an apparatus for converting the digital signal into an intermediate frequency which is an analog signal by a D / A converter.

The fourth processing means includes: an apparatus for amplifying or attenuating the intermediate frequency signal to obtain a required gain; and an apparatus for low pass filtering to remove unwanted signals included in the intermediate frequency signal; and the intermediate apparatus by a mixer. An apparatus for upconverting a frequency signal to an RF frequency; and an apparatus for amplifying the RF signal to obtain a required gain; and an apparatus for bandpass filtering to remove a signal other than the required band.                     

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a block diagram showing the use of a signal processing apparatus for improving communication quality by identifying and removing pseudonoise codes according to the present invention. As shown, the RF signal input through the reception antenna 401 is filtered by only the reception band filter 402 to be amplified with the noise suppressed as much as possible by the low noise amplifier 403, and the oscillator 408. The local oscillation signal is received from the N-B and down-converted to the intermediate frequency through the first mixer 404. In addition, the intermediate frequency signal is filtered by the SAW filter 405 and the strength of the signal is properly adjusted by the first amplifier 406 and the first attenuator 407.

The intermediate frequency signal is converted into a digital signal by the A / D converter 301, and the A / D converted signal identifies a pseudo noise code of a base station signal to be retransmitted by a PN detector in the digital signal processor 302. The PN generator generates the same PN as other pseudonoise signals, subtracts it, removes it, and then converts the analog signal back to an analog signal by the D / A converter 303.

The signal converted to analog through the digital signal processing is amplified by the second amplifier 409 and passed through the low pass filter 410, and then the level is adjusted by the second attenuator 411, and then the second The mixer 412 is upconverted to the RF signal. The upconverted RF signal is amplified by the power amplifier 413, band-pass filtered by the transmit band filter 414, and then transmitted via the transmit antenna 415.

FIG. 5 is a block diagram illustrating the pseudonoise code identification and elimination algorithm of FIG. 4. Signals conforming to CDMA (IS-95, CDMA2000, WCDMA, etc.) signals and other standards converted from analog signals to digital signals from the A / D converter 501 are intended to be retransmitted when viewed at the output of the A / D converter 501. Signals received from a plurality of base stations or terminals, together with signals from the base stations are received through different paths, respectively.

Here, the output signal of the A / D converter 501 is frequency-converted into a baseband signal by the first digital mixer 509, and the basebanded I and Q signals are respectively transmitted to the first digital filter 502. As a result, only the frequency according to the carrier or the bandwidth conforming to the predetermined communication standard is output. Also, the basebanded I and Q signals are branched to pass only signals of individual channels (individual FA in case of CDMA) by the second digital filter 502-1, respectively, and the individual FA signals are PN detectors (Searcher). 504 and a PN tracker 507.

The PN detector 504 detects a pilot or a preamble signal of each signal from multipath signals of multiple base stations or base stations to be retransmitted, thereby determining time delay information (t _d ) and phase of each pilot signal. Information? And amplitude information A are extracted. The time delay, phase, and amplitude information is passed to the PN tracker 507 to track t _d , φ, A of each pilot that changes over time. The t _d , φ, and A of each pilot that changes according to the time tracked by the PN tracker 507 are transferred to the PN generator 505, and the PN generator 505 changes each time according to the time. Using the pilot's t _d , φ, A to generate the same PN as the pseudonoise signals to be removed, the generated signal is filtered by the baseband filter 506 only after the individual FA bands and then the fourth digital mixer 510. The baseband signal is up-converted through -1) and input to the subtractor 508 to remove the unwanted noise signal.

That is, when the time delay, phase and amplitude information of the multipath signal of the base station to be retransmitted by the PN detector 504 and the signals received from the plurality of base stations or the terminals are detected, the PN tracker 507 determines the information. The same kind of information (t _d , φ, A) is continuously tracked from the pilots of the signals that change over time based on the reference, and the t _d , of each pilot that changes over time tracked by the PN tracker. By using φ and A, the PN generator 505 generates a pseudo noise signal to be removed and passes it through the subtractor 508 so that unnecessary signals are removed and only the signal of the intended base station is relayed.

5, the PN tracker 507, the PN generator 505, and the baseband filter 506 constitute the PN removal circuit unit 500 as an aggregate and the PN removal circuit unit 500. ) Is provided for each FA to eliminate unnecessary signals for each FA, and the relay device according to the present invention is not limited to retransmitting only a single FA.

In addition, the first digital filter 502 of the signal processing apparatus according to the present invention has a bandwidth (CDMA) for each communication scheme regardless of the forward link signal and the reverse link signal received through the receiving antenna independently of the unnecessary signal cancellation scheme. (1.23MHz for WCDMA, 5MHz for WCDMA, etc.) to improve out-of-band signal suppression and improve signal purity and efficiency of high-power amplifiers.FIR (Finite Impulse Response) or IIR Scheme and the like can be used.                     

FIG. 6 is a block diagram illustrating another embodiment of the pseudonoise code identification and removal algorithm of FIG. 6 illustrates a method of branching from the output of the first digital filter 502 without branching the branch signal for digital signal processing from the first digital mixer 509 in FIG. This is only a difference in the implementation of the signal processing apparatus according to the present invention, and the configuration and operation of the PN detector 504 and the PN elimination circuit unit 500 at the rear end of the first digital filter 502 are the same as in FIG. 5. .

7 is a view showing the removal of the pseudo noise code of the relay apparatus according to the prior art and the present invention, Figure 7 (a) shows a relay device according to the prior art and Figure 7 (b) is a relay device according to the present invention Indicates. As shown in the related art, in the conventional relay apparatus, not only the pseudonoise codes PN A of the target base station but also the pseudonoise codes PN B and PN C of neighboring base stations are not removed at the output terminal, The relay device can be seen that the pseudonoise codes (PN B, PN C) of neighboring base stations are removed or very weak at the output terminal, and only the pseudonoise codes (PN A) of the target base station are normally relayed.
8 and 9 are block diagrams of a relay apparatus using a signal processing apparatus for improving communication quality by identifying and removing pseudo noise codes according to the present invention, and FIG. 7 shows a method of receiving and retransmitting an RF signal from a base station. 8 is a diagram illustrating a method of retransmitting an RF signal by being wired to a base station by a transmission line or the like.

7 and 8, the relay device according to the present invention includes a first duplexer 601 and a first low noise amplifier 602 and a first power amplifier 603 of a forward link, and a second duplexer 604 of a reverse link. Since only the second low noise amplifier 605 and the second power amplifier 606 need to be applied to the digital signal processing apparatus 600, the system configuration becomes very simple.

In addition, when connected to the base station by a transmission line or the like as shown in Figure 8, a variety of lines such as high-frequency coaxial (opaxial) cable, optical line, UTP cable can be used, in particular a large number of remote modules ( In the case of a relay device retransmitted in a distributed manner using a remote module, a wired telephone line or a CATV public hearing network using VDSL communication may be used.                     

Therefore, the relay device according to the present invention can be easily operated by the operator considering the radio wave environment of the shadow area, and can be widely applied to various relay systems only by changing the software by digital signal processing, and using digital signal processing technology. By eliminating unnecessary signals at baseband, wideband is possible, which overcomes the limitation of narrowband of conventional analog interference cancellation system. That is, the present invention is a technology that analyzes the signal for each channel by digital signal processing of the entire bandwidth, and is not limited to a specific system, and can be widely applied to various mobile communication methods (IS95, GSM, CDMA2000, WCDMA, etc.) through software upgrade. Can be.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

As described above, the present invention converts the RF signal received from the base station into a digital signal, and then identifies a pseudo noise code of the base station signal to be retransmitted among the RF signals by the digital signal processor, and removes other pseudo noise signals. This not only improves the communication quality, but also makes it easier for operators to operate the network considering the radio wave environment of the shadow area, and can be widely applied to various relay systems only by changing the software by digital signal processing. Since the unnecessary signal is removed from the baseband by using a wideband can be effective.

Claims (10)

A method of processing and retransmitting a signal received from a base station or a communication system by a wired or wireless connection, By first processing means for converting the received RF signal into an intermediate frequency; and Converts the intermediate frequency, which is an analog signal, into a digital signal, downconverts the digital signal into a baseband digital signal, and then identifies a pseudo-noise code of a base station signal to be retransmitted by a PN detector in a digital signal processor, and By second processing means for generating a PN equal to the other pseudonoise signals, subtracting the same, and removing the same; By third processing means for up-converting the DSP-processed baseband digital signal and converting it back into an analog signal; And And a fourth processing means for converting the intermediate frequency converted into analog into an RF signal. The signal processing method for improving communication quality by identifying and removing pseudo-noise codes. The method of claim 1, wherein the step by the second processing means comprises: The output signal of the A / D converter is frequency-converted by the first digital mixer into a baseband signal, the baseband signal is branched and input to the PN detector and the PN tracker, After detecting a pilot or a known signal of each signal by the PN detector, the time delay information, phase information, amplitude information is extracted and transferred to the PN tracker, The PN tracker tracks time delay information, phase information, and amplitude information of each pilot or previously known signal that changes with time, and generates and subtracts the same PN from the results as pseudo noise signals to be removed by the PN generator. And eliminating unnecessary pseudo-noise signals, thereby improving communication quality by identifying and removing pseudo-noise codes. An apparatus for processing and retransmitting a signal received from a base station or a communication system by a wired or wireless connection, First processing means for converting the received RF signal into an intermediate frequency; Converts the intermediate frequency, which is an analog signal, into a digital signal, downconverts the digital signal into a baseband digital signal, and then identifies a pseudo-noise code of a base station signal to be retransmitted by a PN detector in a digital signal processor, and Second processing means for generating the same PN as other pseudonoise signals, subtracting it, and removing the same to process DSP; Third processing means for up-converting the DSP-processed baseband digital signal and converting it back to an analog signal; And And fourth processing means for converting the intermediate frequency converted into analog into an RF signal. The signal processing apparatus for improving communication quality by identifying and removing pseudo-noise codes. The method of claim 3, wherein the first processing means, An apparatus for low noise amplifying the RF signal received from the base station; and An apparatus for bandpass filtering to remove signals other than required bands; and An apparatus for down converting the RF signal into an intermediate frequency by a mixer; and Apparatus for filtering SAW to remove noise components included in the intermediate frequency; and And a device for amplifying or attenuating the intermediate frequency signal to obtain a required gain. The method of claim 3, wherein the second processing means, An apparatus for converting the intermediate frequency signal into digital by an A / D converter; An apparatus for downconverting the digital signal into a baseband digital signal; An apparatus for identifying a pseudonoise code of a base station signal to be retransmitted by a PN detector from the baseband digital signal and generating a same PN as other pseudonoise signals by subtracting the PN generator, subtracting it, and removing the same; Signal processing device for improving the communication quality by identifying and removing pseudo-noise code, characterized in that. The DSP processing apparatus according to any one of claims 3 and 5, wherein An apparatus for converting the intermediate frequency signal into digital by an A / D converter; An apparatus for downconverting the digital signal to a baseband signal; An apparatus for filtering the baseband signal through a digital filter; An apparatus for branching the baseband signal to detect a pilot or a previously known signal of each signal, and extracting time delay information, phase information, and amplitude information and transmitting the extracted time delay information to a PN tracker; An apparatus for tracking time delay information, phase information, and amplitude information of each pilot or previously known signal that changes over time and conveys the result to a PN generator; An apparatus for generating the same PN as pseudo noise signals to be removed by using time delay information, phase information, and amplitude information of each pilot or a known signal that changes with time; An apparatus for subtracting the generated pseudonoise signal from the baseband signal; An apparatus for upconverting the baseband signal to a digital signal; And a device for converting the digital signal into an intermediate frequency by means of a D / A converter. The DSP processing apparatus according to any one of claims 3 and 5, wherein A PN detector which receives the baseband signal, detects a pilot or a known signal of each signal, and extracts time delay information, phase information, amplitude information, and transmits the extracted information to a PN tracker; Based on the time delay information, phase information, and amplitude information detected by the PN detector, time delay information, phase information, and amplitude information of each pilot or known signal that changes with time are tracked, and the result is transmitted to the PN generator. Delivering at least one PN tracker; and At least one PN generator for generating a PN identical to a pseudo-noise signal to be removed by using time delay information, phase information, and amplitude information of each pilot or previously known signal that changes according to the time received from the PN tracker; and At least one baseband filter for filtering for each FA the same PN as the pseudonoise signal to be removed generated by the PN generator; and And a subtractor for subtracting the output signal of the baseband filter from the output signal of the first digital filter to remove the unnecessary signal. And a PN removal circuit unit comprising the PN tracker, the PN generator, and the baseband filter as one aggregate. Each signal processing device improves communication quality by identifying and removing pseudo-noise codes. The method of claim 3, wherein the third processing means, An apparatus for up-converting the DSP processed baseband digital signal to a digital signal; and And a device for converting the digital signal to an intermediate frequency, which is an analog signal, by a D / A converter. The method of claim 3, wherein the fourth processing means, An apparatus for amplifying or attenuating the intermediate frequency signal to obtain a required gain; A low pass filtering device to remove unwanted signals included in the intermediate frequency signal; An apparatus for up-converting the intermediate frequency signal to an RF frequency by a mixer; An apparatus for amplifying the RF signal to obtain a required gain; And a bandpass filtering device to remove signals other than the required bands. The method of claim 3, wherein And the connection between the base station or the communication system and the relay device is any one of a group of wired transmission lines consisting of a high frequency coaxial cable, an optical line, a UTP cable, a wired telephone line, and a CATV public hearing network.

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