WO2007043776A1 - Appareil et procede de pre-egalisation permettant de reduire le temps de propagation dans un repeteur sur canal - Google Patents

Appareil et procede de pre-egalisation permettant de reduire le temps de propagation dans un repeteur sur canal Download PDF

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Publication number
WO2007043776A1
WO2007043776A1 PCT/KR2006/004001 KR2006004001W WO2007043776A1 WO 2007043776 A1 WO2007043776 A1 WO 2007043776A1 KR 2006004001 W KR2006004001 W KR 2006004001W WO 2007043776 A1 WO2007043776 A1 WO 2007043776A1
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WO
WIPO (PCT)
Prior art keywords
filter coefficient
equalization
signal
taps
modified
Prior art date
Application number
PCT/KR2006/004001
Other languages
English (en)
Inventor
Heung-Mook Kim
Sung-Ik Park
Jae-Hyun Seo
Ho-Min Eum
Yong-Tae Lee
Seung-Won Kim
Soo-In Lee
Original Assignee
Electronics And Telecommunications Research Institute
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR1020060034598A external-priority patent/KR100778336B1/ko
Application filed by Electronics And Telecommunications Research Institute filed Critical Electronics And Telecommunications Research Institute
Priority to US12/089,468 priority Critical patent/US20080267266A1/en
Publication of WO2007043776A1 publication Critical patent/WO2007043776A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/02—Arrangements for relaying broadcast information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03343—Arrangements at the transmitter end
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/03433—Arrangements for removing intersymbol interference characterised by equaliser structure
    • H04L2025/03439—Fixed structures
    • H04L2025/03445—Time domain
    • H04L2025/03471—Tapped delay lines
    • H04L2025/03477—Tapped delay lines not time-recursive

Definitions

  • the present invention relates to an on-channel repeater; and, more particularly, to a pre-equalization apparatus that can reduce time delay caused by a filter used in a pre- equalization process in an on-channel repeater, and a method thereof.
  • main transmitters and repeaters are disposed to provide a broadcasting service according to natural features, geographical objects, and broadcasting coverage of a broadcasting station.
  • the repeaters are set up in areas where broadcasting signals from a main transmitter are received weakly to resolve the problem of weak signal reception in the areas and broaden the coverage of the main transmitter.
  • FIG. 1 is a diagram showing a broadcasting service using conventional repeaters, each of which uses a different frequency from main transmitter frequency.
  • a main transmitter 101 transmits signals in a transmission frequency A
  • the repeaters 102 to 105 transmits the signals in transmission frequencies B, C, D and E, respectively, which are different from the transmission frequency A.
  • the conventional repeaters resolve the problem of weak signal reception from the main transmitter 101 and broaden the broadcasting coverage by using a different frequency. Since the repeaters use a plurality of frequency bands, the conventional broadcasting system requires much frequency resources and this is quite inefficient in the respect of using frequency.
  • FIG. 2 is a diagram illustrating a service using on-channel repeaters.
  • the on- channel repeaters repeat signals in the same frequency.
  • a main transmitter 201 sends out signals in a transmission frequency A, and on-channel repeaters 202 to 205 repeat the signals in the same frequency A.
  • FIG. 3 is a block view showing an on-channel repeater. The operation of the on- channel repeater will be described with reference to Fig. 3.
  • the on-channel repeater includes a reception antenna 301, a Radio Frequency (RF) receiver 302, an Intermediate Frequency (IF) down-converter 303, a demodulator 304, an equalizer 305, a modulator 306, an RF up-converter 307, a high-power amplifier 308, a mask filter 309, and a transmission antenna 310.
  • RF Radio Frequency
  • IF Intermediate Frequency
  • the RF receiver 302 receives RF signals transmitted from a main transmitter or another repeater through the reception antenna 301.
  • the IF down-converter 303 down- converts the received RF signals into IF signals.
  • the demodulator 304 demodulates the IF signals obtained from the frequency down-conversion into baseband signals.
  • the equalizer 305 equalizes the baseband signals to compensate for signal distortion caused in a transmission channel and remove feedback signals generated due to low isolation of the transmission and reception antennas of the on-channel repeater.
  • the modulator 306 modulates channel distortion-compensated baseband signals into IF signals.
  • the RF up-converter 307 up-converts the IF signals into RF signals.
  • the high-power amplifier 308 amplifies the RF signals obtained from the frequency up-conversion.
  • the mask filter 309 eliminates out of channel emission and spurious signals and transmits the filtered RF signals through the transmission antenna 310.
  • receivers include an equalizer to remove multi-path signals.
  • the equalizer can remove signals temporally delayed and inputted in the same frequency band, other than desired signals.
  • the broadcasting system of Fig. 3 can be realized based on an assumption that the temporal difference between an output signal of the on-channel repeaters received in the receiver and an output signal of the main transmitter received in the receiver should be small. In short, the time delay of the on-channel repeaters should be shortened as much as possible.
  • the on-channel repeater shown in Fig. 3 includes a mask filter 309 in a transmitting part.
  • the mask filter 309 causes much linear distortion in consideration of preventing out-of-band radiation. The linear distortion degrades the quality of transmission signals and brings about reduced broadcasting coverage of the on-channel repeater.
  • the on-channel repeater should improve the quality of broadcasting signals by using a pre-equalization method and compensating for the linear distortion caused in the RF up-converter, the high-power amplifier, and the mask filter, which are constituent elements following the modulator 306.
  • the pre-equalization is realized to be included in the modulator 306 of the on-channel repeater shown in Fig. 3.
  • the modulator 306 of the on-channel repeater is disclosed by Seong-Ik Park et al. in Korean Patent Publication No. 10-2005-0040636 entitled "Modulating apparatus for reducing time delay of on-channel repeater in terrestrial digital TV broadcasting system, particularly regarding to expanding relay area and increasing use efficiency of limited frequency resources" published on May 3, 2005.
  • Fig. 4 is a block view describing the modulator 306 of the on-channel repeater.
  • the modulator 306 includes a baseband signal generating unit 401, a pilot adding unit 402, a pre-equalization filter coefficient generating unit 403, a pre-equalization filtering unit 404, an up-sampling unit 405, a filtering unit 406, an IF up-converting unit 407, an I-Q adding unit 408, and a digital-to-analog (DA) converting unit (DAC) 409.
  • the baseband signal generating unit 401 forms baseband signals by combining fields and segment sync signals.
  • the pilot adding unit 402 adds a pilot signal to a baseband signal generated in the baseband signal generating unit 401.
  • the pre-equalization filtering unit 404 filters the baseband signal including pilot signal with a pre-equalization filter generated in the pre-equalization filter coefficient generating unit 403 to thereby produce a pre-equalization-filtered baseband signal.
  • the up-sampling unit 405 up- samples the pre-equalization-filtered baseband signal.
  • the filtering unit 406 filters the up-sampled baseband signal into an In-phase (I) signal and a Quadrature (Q) signal through a pulse shaping filter.
  • the IF up-converting unit 407 up-converts the filtered I and Q baseband signals into IF I and Q signals.
  • the I-Q adding unit 408 summates the IF I and Q signals obtained from the IF up-conversion and thereby produces an IF signal.
  • the DA converting unit 409 converts the digital IF signal into an analog IF signal.
  • the pre-equalization filter generated in the pre-equalization filter coefficient generating unit 403 is operated based on a symbol rate, and the total number of taps included in the pre-equalization filter is Cl +D 1+1.
  • a main tap is disposed at a position of Cl+1 in the front.
  • the time delay caused by the pre-equalization filtering unit 404 is Cl symbol time.
  • the filtering unit 406 includes an I filter and a Q filter.
  • the number of taps in each of the I filter and the Q filter is C2+D2+1.
  • a main tap is disposed at a position of C2+1 in the front.
  • the modulator 306 adopting the conventional pre-equalization method comes to have time delay of Cl + C2/K symbol time.
  • the adoption of the pre-equalization method increases time delay of the on-channel repeater by Cl symbol time.
  • a pre- equalization apparatus for an on-channel repeater repeating signals in a same frequency, which includes: a baseband signal generating unit for forming a baseband signal by combining an inputted signal, field sync signal and segment sync signal; a pilot adding unit for adding a pilot signal to the baseband signal; an up-sampling unit for up-sampling the baseband signal having the pilot signal added thereto; a pre- equalization filter coefficient generating unit for generating a pre-equalization filter coefficient; a modified filter coefficient generating unit for generating a modified filter coefficient by using the pre-equalization filter coefficient and a given filter coefficient; and a filtering unit for filtering the up-sampled signal by using the modified filter coefficient.
  • a pre- equalization method for an on-channel repeater repeating signals in a same frequency which includes the steps of: a) forming a baseband signal by combining an inputted signal, field sync signal and segment sync signal; b) adding a pilot signal to the generated baseband signal; c) up-sampling the baseband signal having the pilot signal added thereto; d) generating a pre-equalization filter coefficient; e) generating a modified filter coefficient by using the pre-equalization filter coefficient and a given filter coefficient; and f) filtering the up-sampled signal by using the modified filter coefficient.
  • the present invention can minimize time delay in an on-channel repeater and increase an efficiency of using frequency resources, whose quantity is limited, with an improved on-channel repeating performance.
  • FIG. 1 is a view showing a broadcasting service using conventional repeaters
  • FIG. 2 is a view illustrating a broadcasting service using conventional on-channel repeaters
  • FIG. 3 is a block view describing a structure of an on-channel repeater
  • FIG. 4 is a block view showing a modulator of the on-channel repeater
  • FIG. 5 is a block view describing a pre-equalization apparatus for an on-channel repeater in accordance with an embodiment of the present invention
  • Fig. 6 shows a modified filter coefficient generation process in a modified filter coefficient generating unit
  • Fig. 7 is a flowchart describing a pre-equalization method of the on-channel repeater in accordance with an embodiment of the present invention. Mode for the Invention
  • a pre-equalization apparatus and method of an on-channel repeater suggested in the present invention is appropriate for digital television broadcasting based on the Advanced Television Systems Committee (ATSC) Protocols and Digital Video Broadcasting (DVB).
  • ATSC Advanced Television Systems Committee
  • DVD Digital Video Broadcasting
  • the present invention is not limited to them, and it can be applied to any environment where repeaters are needed to form a general single frequency network.
  • FIG. 5 is a block view describing a pre-equalization apparatus for an on-channel repeater in accordance with an embodiment of the present invention.
  • the pre-equalization apparatus for an on-channel repeater suggested in the present invention includes a baseband signal generating unit 501, a pilot adding unit 502, an up-sampling unit 503, a pre-equalization filer coefficient generating unit 504, a modified filter coefficient generating unit 505, a filtering unit 506, an intermediate frequency (IF) up-converting unit 507, an I-Q adding unit 508, and a digital-to-analog converting unit (DAC) 509.
  • a baseband signal generating unit 501 includes a baseband signal generating unit 501, a pilot adding unit 502, an up-sampling unit 503, a pre-equalization filer coefficient generating unit 504, a modified filter coefficient generating unit 505, a filtering unit 506, an intermediate frequency (IF) up-converting unit 507, an I-Q adding unit 508, and a digital-to-analog converting unit (DAC) 509.
  • IF intermediate frequency
  • I-Q adding unit 508 includes a digital-to-analog
  • the baseband signal generating unit 501 forms a baseband signal by combining an output signal of the equalizer used in the on-channel repeater, a field sync signal, and a segment sync signal, and the pilot adding unit 502 adds a pilot signal to the baseband signal formed in the baseband signal generating unit 501.
  • the up-sampling unit 503 performs up-sampling onto the baseband signal having the pilot signal added thereto, and the filtering unit 506 converts the up- sampled baseband signal into an In-phase (I) signal and a Quadrature (Q) signal and performs filtering onto the I and Q signals.
  • the filtering unit 506 may perform the filtering by using an Equi-Ripple (ER) filter and a window technique, or it may perform the filtering by using a Square Root Raised Cosine (SRRC) filter and the window technique, or it may perform the filtering by using only the ER filter.
  • ER Equi-Ripple
  • SRRC Square Root Raised Cosine
  • the pre-equalization filter coefficient generating unit 504 generates a pre- equalization filter coefficient based on a reference signal, which may be varied by a system operator.
  • the modified filter coefficient generating unit 505 performs convolution onto the pre-equalization filter coefficient and an existing filter coefficient of the filtering unit 506 to thereby produce a new filter coefficient and transmits the newly generated filter coefficient to the filtering unit 506. Filtering in the filtering unit 506 is performed based on the new filter coefficient.
  • the IF up-converting unit 507 up-converts the filtered I and Q signals into IF I and Q signals, and the I-Q adding unit 508 summates the IF I and Q signals into an IF signal.
  • the DA converting unit 509 converts the IF signal into an analog signal.
  • the filter coefficient of the filtering unit 506 is provided by the pre-equalization filter coefficient generating unit 504 and the modified filter coefficient generating unit 505.
  • the pre-equalization filter coefficient generating unit 504 generates a pre- equalization filter coefficient, in which the total number of taps is Nl+Ml+1 and a main tap is disposed at a position of Nl+1, based on a predetermined pre-equalization algorithm operating at an up-sampling rate L, and transmits the pre-equalization coefficient to the modified filter coefficient generating unit 505.
  • the modified filter coefficient generating unit 505 performs convolution onto the pre-equalization filter coefficient transmitted from the pre-equalization filter coefficient generating unit 504 and a given filter coefficient of the filtering unit 506.
  • the given filter coefficient of the filtering unit 506 the number of the entire taps is N2+M2+1 and a main tap is disposed at a position of N2+1.
  • a new filter coefficient obtained from the convolution has N1+N2+M1+M2+1 taps in total and a main tap disposed at a position of N1+N2+1.
  • the modified filter coefficient generating unit 505 may remove some taps of the filter coefficient obtained from the convolution, if it is necessary to remove the filter coefficient to reduce time delay. In other words, the modified filter coefficient generating unit 505 adjusts the number of pre-taps N3 (N3 ⁇ N1+N2) among the total number of the taps, which is N1+N2+M1+M2+1, and, if necessary, it may also adjust the number of post-taps M3 (M3 ⁇ M1+M2) to make the total number of taps to be N3+M3+1 and make the main tap disposed at a positioned of N3+1 so that the filtering unit 506 can perform filtering with a short time delay.
  • FIG. 6 shows a modified filter coefficient generation process in the modified filter coefficient generating unit 505.
  • the pre-equalization filter coefficient generating unit 504 generates a pre-equalization filter coefficient in which the total number of taps is Nl+Ml+1, and the number of pre-taps is Nl and the number of post-taps is Ml based on a predetermined pre-equalization algorithm operating at an up-sampling rate L.
  • the filtering unit 506 has a given filter coefficient in which the total number of taps is N2+M2+1, and the number of pre-taps is N2, while the number of post-taps is M2.
  • the modified filter coefficient generating unit 505 performs convolution onto the pre-equalization filter coefficient generated in the pre-equalization filter coefficient generating unit 504 and the given filter coefficient of the filtering unit 506.
  • a filter coefficient obtained from the convolution which will be simply referred to as a convolution filter coefficient, has N1+N2+M1+M2+1 taps in total, N1+N2 pre- taps, and M1+M2 post-taps.
  • the modified filter coefficient generating unit 505 may remove the convolution filter coefficient to reduce time delay, if necessary.
  • the number of the pre-taps is adjusted into N3 (N3 ⁇ N1+N2)
  • the number of the post- taps may be adjusted into M3 (M3 ⁇ M1+M2), if necessary.
  • the number of pre-taps of the filtering unit 506 becomes N3 (N3 ⁇ N1+N2) by the pre-equalization filter coefficient generating unit 504 and modified filter coefficient generating unit 505. Therefore, time delay of the filtering unit 506 is expressed as shown in Equation 1.
  • Equation 2 the time delay of the Equation 1 can be induced as shown in Equation 2.
  • the filtering unit 506 of Fig. 5 can have the same number of filter coefficient as the filtering unit 406 of Fig. 4, which has a time delay of C1+C2/K, but reduced time delay as shown in Equation 2.
  • Fig. 7 is a flowchart describing a pre-equalization method of the on-channel repeater in accordance with an embodiment of the present invention.
  • a baseband signal is formed by combining an output signal of an equalizer used in the on-channel repeater, a field sync signal, and segment sync signal.
  • step S702 a pilot signal is added to the baseband signal and, at step S703, the baseband signal with the pilot signal added thereto is up-sampled.
  • a pre-equalization filter coefficient is generated based on a predetermined pre-equalization algorithm operating at the up-sampling rate.
  • convolution is performed onto the generated pre-equalization filter coefficient and the predetermined filter coefficient to thereby generate a new filter coefficient, which will be referred to as a convolution filter coefficient.
  • a pre-equalization filter coefficient in which the total number of taps is Nl+Ml+1 and a main tap is positioned at Nl+ 1 is generated.
  • the generated pre- equalization filter coefficient is convoluted with a given filter coefficient in which the total number of taps is N2+M2+1 and a main tap is disposed at a position of N2+1.
  • the convolution filter coefficient has N1+N2+M1+M2+1 taps in total and a main tap disposed at a position of N1+N2+1.
  • step S706 some of the convolution filter coefficient is removed to reduce time delay.
  • the number of the pre-taps N3 among the total number of taps i.e., N1+N2+M1+M2+1, is adjusted to perform filtering with a short time delay. If necessary, the number of post-taps M3 may be adjusted, too (M3 ⁇ M1+M2).
  • the up-sampled baseband signal is filtered using a modified convolution filter coefficients.
  • the filtered I and Q signals are up-converted into IF signals and, at step S709, the IF I and Q signals are summated into a signal.
  • the obtained IF signal is converted into an analog signal.
  • the method of the present invention which is described above can be realized as a program and stored in a computer-readable recording medium such as CD-ROM, RAM, ROM, a floppy disk, a hard disk, and a magneto-optical disk. Since the process can be easily realized by those skilled in the art to which the present invention pertains, the process will not be described in detail herein.
  • the present invention can improve the efficiency of frequency resources, whose quantity is limited, with an improved performance of an on-channel repeater as well as minimizing time delay of an on-channel repeater.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radio Relay Systems (AREA)

Abstract

L'invention concerne un appareil et un procédé de pré-égalisation pouvant réduire le temps de propagation d'un répéteur sur canal. L'appareil de pré-égalisation réduit le temps de propagation dans un répéteur sur canal par génération d'un coefficient de filtrage modifié à partir d'un coefficient de filtrage donné et d'un coefficient de filtrage de pré-égalisation après un processus de suréchantillonnage et par filtrage de signaux suréchantillonnés. L'appareil de pré-égalisation comprend : une unité de génération de signal de bande de base permettant de former un signal de bande de base par combinaison d'un signal entré, d'un signal de synchronisation de champs et d'un signal de synchronisation de segments ; une unité d'addition de signaux pilotes permettant d'ajouter un signal pilote au signal de bande de base ; une unité de suréchantillonnage permettant de suréchantillonner le signal de bande de base présentant le signal pilote ; une unité de génération de coefficient de filtrage de pré-égalisation permettant de générer un coefficient de filtrage de pré-égalisation ; une unité de génération de coefficient de filtrage modifié permettant de générer un coefficient de filtrage modifié au moyen du coefficient de filtrage de pré-égalisation et d'un coefficient de filtrage donné ; ainsi qu'une unité de filtrage permettant de filtrer le signal suréchantillonné au moyen du coefficient de filtrage modifié.
PCT/KR2006/004001 2005-10-07 2006-10-04 Appareil et procede de pre-egalisation permettant de reduire le temps de propagation dans un repeteur sur canal WO2007043776A1 (fr)

Priority Applications (1)

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US12/089,468 US20080267266A1 (en) 2005-10-07 2006-10-04 Pre-Equalization Apparatus and Method for Reducing Time Delay in On-Channel Repeater

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR20050094419 2005-10-07
KR10-2005-0094419 2005-10-07
KR1020060034598A KR100778336B1 (ko) 2005-10-07 2006-04-17 동일채널 중계기의 시간 지연을 줄이기 위한 전치등화 장치및 그 방법
KR10-2006-0034598 2006-04-17

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20020088304A (ko) * 2001-05-21 2002-11-27 엘지전자 주식회사 디지탈 티브이 중계기
US20040237117A1 (en) * 2003-05-20 2004-11-25 Sung-Ik Park On-channel repeating apparatus and method for terrestrial digital television broadcasting service
US20050094717A1 (en) * 2003-10-29 2005-05-05 Sung-Ik Park Modulation apparatus for reducing time delay of on-channel repeater in terrestrial digital TV broadcasting system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20020088304A (ko) * 2001-05-21 2002-11-27 엘지전자 주식회사 디지탈 티브이 중계기
US20040237117A1 (en) * 2003-05-20 2004-11-25 Sung-Ik Park On-channel repeating apparatus and method for terrestrial digital television broadcasting service
US20050094717A1 (en) * 2003-10-29 2005-05-05 Sung-Ik Park Modulation apparatus for reducing time delay of on-channel repeater in terrestrial digital TV broadcasting system

Non-Patent Citations (1)

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Title
WANG X. ET AL.: "Transmitter identification uisng embedded spread spectrum sequences", COMMUNICATION TECHNOLOGY PROCEEDINGS, vol. 2,9-11, April 2003 (2003-04-01), pages 1517 - 1523, XP010644255 *

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