WO2008069556A1 - Amplitude-differential phase shift keying modulation apparatus and method - Google Patents

Amplitude-differential phase shift keying modulation apparatus and method Download PDF

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Publication number
WO2008069556A1
WO2008069556A1 PCT/KR2007/006259 KR2007006259W WO2008069556A1 WO 2008069556 A1 WO2008069556 A1 WO 2008069556A1 KR 2007006259 W KR2007006259 W KR 2007006259W WO 2008069556 A1 WO2008069556 A1 WO 2008069556A1
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WIPO (PCT)
Prior art keywords
dpsk
pilot signals
ask
amplitude
shift keying
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PCT/KR2007/006259
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French (fr)
Inventor
Hyoungsoo Lim
Young-Su Kim
Seomee Choi
Jong-Soo Lim
Dae-Ken Kwon
Hyoung-Nam Kim
Original Assignee
Electronics And Telecommunications Research Institute
Institute For Research Industry Cooperation, Pnu
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Application filed by Electronics And Telecommunications Research Institute, Institute For Research Industry Cooperation, Pnu filed Critical Electronics And Telecommunications Research Institute
Priority to EP07851250A priority Critical patent/EP2090049A4/en
Publication of WO2008069556A1 publication Critical patent/WO2008069556A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/38—Demodulator circuits; Receiver circuits
    • H04L27/389—Demodulator circuits; Receiver circuits with separate demodulation for the phase and amplitude components
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/02—Details
    • H04L12/16—Arrangements for providing special services to substations
    • 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
    • H04L25/0202—Channel estimation
    • H04L25/0224—Channel estimation using sounding signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/02—Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H04L27/20—Modulator circuits; Transmitter circuits
    • H04L27/2032—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner
    • H04L27/2053—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases
    • H04L27/206—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases using a pair of orthogonal carriers, e.g. quadrature carriers
    • H04L27/2067—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases using a pair of orthogonal carriers, e.g. quadrature carriers with more than two phase states
    • H04L27/2071—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases using a pair of orthogonal carriers, e.g. quadrature carriers with more than two phase states in which the data are represented by the carrier phase, e.g. systems with differential coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H04L27/20—Modulator circuits; Transmitter circuits
    • H04L27/2032—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner
    • H04L27/2053—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases
    • H04L27/206—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases using a pair of orthogonal carriers, e.g. quadrature carriers
    • H04L27/2067—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases using a pair of orthogonal carriers, e.g. quadrature carriers with more than two phase states
    • H04L27/2075—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases using a pair of orthogonal carriers, e.g. quadrature carriers with more than two phase states in which the data are represented by the change in carrier phase
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/345—Modifications of the signal space to allow the transmission of additional information
    • H04L27/3461—Modifications of the signal space to allow the transmission of additional information in order to transmit a subchannel
    • H04L27/3483—Modifications of the signal space to allow the transmission of additional information in order to transmit a subchannel using a modulation of the constellation points
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/36—Modulator circuits; Transmitter circuits
    • H04L27/361—Modulation using a single or unspecified number of carriers, e.g. with separate stages of phase and amplitude modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0003—Two-dimensional division
    • H04L5/0005—Time-frequency
    • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT

Definitions

  • the present invention relates to digital communication, and more particularly, to an amplitude-differential phase shift keying (A-DPSK) modulation apparatus capable of improving a transmission speed while guaranteeing compatibility with a conventional system.
  • A-DPSK amplitude-differential phase shift keying
  • a typical method of increasing a data transmission speed is to increase the number of constellation points.
  • a multilevel modulation technique such as quadrature amplitude modulation (16-QAM) that is one of a plurality of widely used methods in a broadcasting system, such as a digital video broadcasting- terrestrial (DVB-T) system. Since the 16-QAM is an in-phase modulation technique, pilot signals have to be transmitted so as to estimate a channel for in-phase demodulation in a receiver. Since the pilot signals, except a phase reference symbol (PRS), are not provided in the terrestrial DMB system, the 16-QAM technique compatible with a conventional system is not suitable for a modulation method of increasing the data transmission speed of the terrestrial DMB system.
  • PRS phase reference symbol
  • Another method for increasing a data transmission speed is a 16-differential amplitude phase shift keying (16-D APSK) modulation method which does not need pilot signals, channel estimation, or equalization.
  • This method operates well in a slow fading channel environment with comparatively constant channel coefficients over two or more continuous OFDM symbol periods. However, since the channel coefficients changes largely between neighboring OFDM symbol periods in a fast fading channel environment in which a terminal moves fast, this method may not operate well.
  • the present invention provides an amplitude-differential phase shift keying
  • amplitude-differential phase shift keying modulation apparatus including: a first modulation unit for DPSK (differential phase shift keying) -modulating a first data sequence; a second modulation unit for ASK (amplitude shift keying)-modulating a second data sequence and inserting pilot signals into the ASK-modulated signal; and a multiplier for multiplying outputs of the first and second modulation units and outputting the multiplication result.
  • DPSK differential phase shift keying
  • ASK amplitude shift keying
  • amplitude-differential phase shift keying demodulation apparatus including: a first demodulation unit for receiving an A-DPSK-modulated signal and DPSK-de- modulating the received signal; a second demodulation unit for extracting pilot signals from the received signal, removing the extracted pilot signals from the received signal, and ASK-demodulating the pilot signals removed A-DPSK-modulated signal.
  • DPSK amplitude-differential phase shift keying modulation method including: DPSK (differential phase shift keying)-modulating a first data sequence; ASK (amplitude shift keying)-modulating a second data sequence; inserting pilot signals into the ASK- modulated signal; and multiplying the DPSK-modulated signal sequence by the pilot signals inserted ASK-modulated signal sequence.
  • a modulation method including: generating a plurality of constellation points with multi- phases having a first amplitude in a constellation diagram by DPSK-modulating a first data sequence; and modulating a second data sequence so as to further generate a plurality of constellation points whose amplitudes are separated from the first amplitude at constant intervals.
  • a demodulation method including: DPSK (differential phase shift keying) -demodulating a received signal which is A-DPSK modulated; extracting pilot signals from the received signal; estimating a channel through which the received signal is transmitted using the extracted pilot signals and outputting amplitudes of the pilot signals from the estimated channel value; removing the pilot signals with the amplitudes from the received signal; and ASK-demodulating the received signals with the pilot signals removed.
  • DPSK differential phase shift keying
  • FIG. 1 is a block diagram illustrating an amplitude-differential phase shift keying
  • FIG. 2 illustrates a constellation diagram of amplitude-differential quadrature phase shift keying (A-DQPSK) modulation data
  • FIG. 3 is a block diagram illustrating an A-DPSK demodulation apparatus according to an embodiment of the present invention.
  • FIG. 4 illustrates simulation results showing receiving performance of a conventional differential quadrature phase shift keying (DQPSK) receiver with respect to an A- DQPSK signal according to the present invention, a conventional DQPSK signal, and a differential amplitude phase shift keying (DAPSK) signal; and
  • DQPSK differential quadrature phase shift keying
  • DAPSK differential amplitude phase shift keying
  • FIG. 5 illustrates simulation results showing receiving performance with respect to an A-DPSK signal and a DAPSK signal under the same condition as shown in FIG. 4.
  • FIG. 1 is a block diagram illustrating an amplitude-differential phase shift keying
  • the A-DPSK modulation apparatus shown in FIG.1 can be employed in a terrestrial digital multimedia broadcasting (DMB) system in which a differential phase shift keying (DPSK) or a differential quadrature phase shift keying (DQPSK) technique is applied to an orthogonal frequency division multiplexing (OFDM) technique.
  • DMB digital multimedia broadcasting
  • DPSK differential phase shift keying
  • DQPSK differential quadrature phase shift keying
  • OFDM orthogonal frequency division multiplexing
  • the A-DPSK modulation apparatus operates based on a modulation method of transmitting main transmission data together with additional transmission data.
  • the main transmission data is modulated according to the conventional DPSK modulation method.
  • the additional transmission data is modulated according to another method different from the DPSK method so as to provide an additional service besides the main transmission data.
  • the A-DPSK modulation apparatus includes a DPSK unit 10 which DPSK-modulates the main transmission data, an amplitude shift keying (ASK) unit 11 which ASK-modulates the additional transmission data, a pilot insertion unit 12 which inserts a pilot into the modulated additional transmission signal, and a multiplier 13.
  • a reference numeral 14 denotes a unit for converting the output A-DPSK signal into an orthogonal frequency division multiplexing (OFDM) symbol.
  • the DPSK unit 10 outputs a transmission symbol generated from the input main transmission data and to be transmitted next, the phase of which is determined relatively to the one of the immediately previously transmitted symbol.
  • the ASK unit 11 allocates an amplitude of a subcarrier differently according to the input additional transmission data. For example, when the additional transmission data is 1, the amplitude of the subcarrier signal is set to ⁇ . When the additional transmission data is 0, the amplitude of the subcarrier signal is set to ⁇ + ⁇ .
  • the pilot insertion unit 12 periodically or non-periodically inserts pilot signals into a modulated signal output from the ASK unit 11. For example, a pilot signal may be inserted into a location of every tenth subcarrier of the modulated signal output from th e ASK unit 11. Alternatively, pilot signals may be inserted into a location after the modulated signals output from the ASK unit 11. Both the transmitting and receiving sides know which subcarrier positions the pilot signals are located at.
  • the multiplier 13 multiplies the output data of the DPSK unit 10 by the output signal of the pilot insertion unit 12 and outputs the multiplication result.
  • FIG. 2 is a constellation diagram of A-DQPSK data in which DPSK and ASK modulation orders are 2.
  • constellation points for the additional transmission data are generated additionally at a constant interval ⁇ in the constellation points of DPSK data for the main transmission data.
  • parameters ⁇ and ⁇ are used to determine a bit error rate of the additional transmission data, except the main transmission data, transmitted through the conventional system and compatibility with the conventional system.
  • the conventional terrestrial DMB data has to be DQPSK-modulated modulation, while the additional transmission data has to ASK-modulated.
  • the conventional terrestrial DMB receiver can successfully demodulate data corresponding to a conventional terrestrial DMB service by considering the A-DQPSK modulated signals and the DAQPSK modulated signals as the DQPSK modulated signals.
  • FIG. 3 is a block diagram illustrating an A-DPSK demodulation apparatus according to an embodiment of the present invention.
  • the shown A-DPSK demodulation apparatus illustrated in FIG. 3 includes a main transmission signal demodulation unit 31 and an additional transmission signal demodulation unit 32.
  • the main transmission signal demodulation unit 31 outputs the main transmission signal by DPSK-demodulating signals received through a channel and then OFDM- demodulated.
  • the DPSK demodulation is performed by using the conventional demodulation method which uses, for example, a one-symbol delay and a complex conjugate multiplier.
  • the additional transmission signal demodulation unit 32 includes a pilot extraction unit 321, a channel amplitude estimation unit 322, a pilot removing unit 323, and an ASK demodulation unit 324.
  • the pilot extraction unit 321 Since the pilot extraction unit 321 knows the locations of the pilot signals, the pilot extraction unit 321 extracts a pilot from a signal which is received through a channel and OFDM-demodulated.
  • the channel amplitude estimation unit 322 performs channel estimation by using the extracted pilot and extracts only amplitude from the estimated channel value.
  • One of conventional channel estimation methods comprising least square estimation and maximum likelihood estimation may be employed as the channel estimation method.
  • the pilot removing unit 323 removes the pilot signals from the transmission signal into which the pilot signals are inserted.
  • the ASK demodulation unit 324 outputs the additional transmission data by demodulating the signal from which the pilot signals are removed by using the estimated amplitude.
  • FIG. 4 illustrates simulation results showing receiving performance of a conventional
  • DQPSK receiver with respect to an A-DQPSK signal according to the present invention, conventional DQPSK and differential amplitude phase shift keying (DAPSK) signals.
  • the simulation is performed with respect to DAB transmission mode 1.
  • a carrier frequency is 200 MHz, a bandwidth is 1.536 MHz, and a frame length is 96 ms.
  • a frame is constructed with 76 OFDM symbols. Each OFDM symbol is constructed with 1,536 subcarriers with an interval of 1 kHz.
  • FIG. 5 illustrates the receiving performance of the A-DPSK modulation technique and the DAPSK modulation technique under the same conditions as the case shown in FIG. 4.
  • the receiving performances of the DAPSK and A-DPSK modulation techniques become largely deteriorated due to interference between subcarriers.
  • the receiving performance of the DAPSK modulation technique becomes deteriorated more than that of the A-DPSK modulation technique.
  • the A-DPSK signal method can improve receiving performance of the terrestrial DMB system in a mobile receiving environment compared with the DAPSK signal method.
  • FIGS. 4 and 5 are cases applied for increasing a data transmission speed of the terrestrial DMB system.
  • the A-DPSK signal method suggested in the present invention can be applied to various digital communication or broadcasting systems besides the terrestrial DMB system.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Power Engineering (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)

Abstract

An amplitude differential shift keying (A-DPSK) modulation apparatus and method, and an A-DPSK demodulation apparatus and method are provided. The A-DPSK modulation apparatus includes: a first modulation unit for DPSK (differential phase shift keying) -modulating a first data sequence; a second modulation unit for ASK (amplitude shift keying)-modulating a second data sequence and inserting pilot signals into the ASK-modulated signal; and a multiplier for multiplying outputs of the first and second modulation units and outputting the multiplication result.

Description

Description
AMPLITUDE- DIFFERENTIAL PHASE SHIFT KEYING MODULATION APPARATUS AND METHOD
[1] This application claims the benefit of Korean Patent Application No.
10-2006-0124121, filed on December 7, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
[2] This work is supported by the IT R&D program of MIC/IITA. [2006-S-017-01, Development of advanced transmission technology for the terrestrial DMB system] Technical Field
[3] The present invention relates to digital communication, and more particularly, to an amplitude-differential phase shift keying (A-DPSK) modulation apparatus capable of improving a transmission speed while guaranteeing compatibility with a conventional system. Background Art
[4] A typical method of increasing a data transmission speed is to increase the number of constellation points. For example, in order to increase a data transmission speed of a terrestrial digital multimedia broadcasting (DMB) system, a multilevel modulation technique such as quadrature amplitude modulation (16-QAM) that is one of a plurality of widely used methods in a broadcasting system, such as a digital video broadcasting- terrestrial (DVB-T) system, is used. Since the 16-QAM is an in-phase modulation technique, pilot signals have to be transmitted so as to estimate a channel for in-phase demodulation in a receiver. Since the pilot signals, except a phase reference symbol (PRS), are not provided in the terrestrial DMB system, the 16-QAM technique compatible with a conventional system is not suitable for a modulation method of increasing the data transmission speed of the terrestrial DMB system.
[5] Another method for increasing a data transmission speed is a 16-differential amplitude phase shift keying (16-D APSK) modulation method which does not need pilot signals, channel estimation, or equalization. This method operates well in a slow fading channel environment with comparatively constant channel coefficients over two or more continuous OFDM symbol periods. However, since the channel coefficients changes largely between neighboring OFDM symbol periods in a fast fading channel environment in which a terminal moves fast, this method may not operate well.
[6] Accordingly, there is needed a modulation method for increasing a transmission speed while maintaining compatibility with a conventional system. Disclosure of Invention Technical Problem [7] The present invention provides an amplitude-differential phase shift keying
(A-DPSK) modulation apparatus and method for increasing a transmission speed while maintaining compatibility with a conventional DPSK modulation method by modulating main transmission data through the DPSK modulation method and modulating additional transmission data through another modulation method. Technical Solution
[8] According to an aspect of the present invention, there is provided an A-DPSK
(amplitude-differential phase shift keying) modulation apparatus including: a first modulation unit for DPSK (differential phase shift keying) -modulating a first data sequence; a second modulation unit for ASK (amplitude shift keying)-modulating a second data sequence and inserting pilot signals into the ASK-modulated signal; and a multiplier for multiplying outputs of the first and second modulation units and outputting the multiplication result.
[9] According to another aspect of the present invention, there is provided an A-DPSK
(amplitude-differential phase shift keying) demodulation apparatus including: a first demodulation unit for receiving an A-DPSK-modulated signal and DPSK-de- modulating the received signal; a second demodulation unit for extracting pilot signals from the received signal, removing the extracted pilot signals from the received signal, and ASK-demodulating the pilot signals removed A-DPSK-modulated signal.
[10] According to still another aspect of the present invention, there is provided an A-
DPSK (amplitude-differential phase shift keying) modulation method including: DPSK (differential phase shift keying)-modulating a first data sequence; ASK (amplitude shift keying)-modulating a second data sequence; inserting pilot signals into the ASK- modulated signal; and multiplying the DPSK-modulated signal sequence by the pilot signals inserted ASK-modulated signal sequence.
[11] According to still another aspect of the present invention, there is provided a modulation method including: generating a plurality of constellation points with multi- phases having a first amplitude in a constellation diagram by DPSK-modulating a first data sequence; and modulating a second data sequence so as to further generate a plurality of constellation points whose amplitudes are separated from the first amplitude at constant intervals.
[12] According to still another aspect of the present invention, there is provided a demodulation method including: DPSK (differential phase shift keying) -demodulating a received signal which is A-DPSK modulated; extracting pilot signals from the received signal; estimating a channel through which the received signal is transmitted using the extracted pilot signals and outputting amplitudes of the pilot signals from the estimated channel value; removing the pilot signals with the amplitudes from the received signal; and ASK-demodulating the received signals with the pilot signals removed. Advantageous Effects
[13] Accordingly, when main transmission data modulated through the conventional modulation method is combined with additional transmission data modulated through another modulation method and the combined data is transmitted through the conventional digital communication or broadcasting system, it is possible to increase a data transmission speed while maintaining compatibility with the conventional system. Specifically, it is also possible to achieve high performance in a fading channel environment in which the terminal moves in a high speed. Description of Drawings
[14] The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
[15] FIG. 1 is a block diagram illustrating an amplitude-differential phase shift keying
(A-DPSK) modulation apparatus according to an embodiment of the present invention;
[16] FIG. 2 illustrates a constellation diagram of amplitude-differential quadrature phase shift keying (A-DQPSK) modulation data;
[17] FIG. 3 is a block diagram illustrating an A-DPSK demodulation apparatus according to an embodiment of the present invention;
[18] FIG. 4 illustrates simulation results showing receiving performance of a conventional differential quadrature phase shift keying (DQPSK) receiver with respect to an A- DQPSK signal according to the present invention, a conventional DQPSK signal, and a differential amplitude phase shift keying (DAPSK) signal; and
[19] FIG. 5 illustrates simulation results showing receiving performance with respect to an A-DPSK signal and a DAPSK signal under the same condition as shown in FIG. 4. Mode for Invention
[20] Hereinafter, the present invention will be described in detail with reference to the attached drawings.
[21] FIG. 1 is a block diagram illustrating an amplitude-differential phase shift keying
(A-DPSK) modulation apparatus according to an embodiment of the present invention.
[22] The A-DPSK modulation apparatus shown in FIG.1 can be employed in a terrestrial digital multimedia broadcasting (DMB) system in which a differential phase shift keying (DPSK) or a differential quadrature phase shift keying (DQPSK) technique is applied to an orthogonal frequency division multiplexing (OFDM) technique.
[23] The A-DPSK modulation apparatus operates based on a modulation method of transmitting main transmission data together with additional transmission data. The main transmission data is modulated according to the conventional DPSK modulation method. The additional transmission data is modulated according to another method different from the DPSK method so as to provide an additional service besides the main transmission data.
[24] As shown in FIG. 1, the A-DPSK modulation apparatus includes a DPSK unit 10 which DPSK-modulates the main transmission data, an amplitude shift keying (ASK) unit 11 which ASK-modulates the additional transmission data, a pilot insertion unit 12 which inserts a pilot into the modulated additional transmission signal, and a multiplier 13. A reference numeral 14 denotes a unit for converting the output A-DPSK signal into an orthogonal frequency division multiplexing (OFDM) symbol.
[25] The DPSK unit 10 outputs a transmission symbol generated from the input main transmission data and to be transmitted next, the phase of which is determined relatively to the one of the immediately previously transmitted symbol.
[26] The ASK unit 11 allocates an amplitude of a subcarrier differently according to the input additional transmission data. For example, when the additional transmission data is 1, the amplitude of the subcarrier signal is set to α. When the additional transmission data is 0, the amplitude of the subcarrier signal is set to α + β.
[27] The pilot insertion unit 12 periodically or non-periodically inserts pilot signals into a modulated signal output from the ASK unit 11. For example, a pilot signal may be inserted into a location of every tenth subcarrier of the modulated signal output from th e ASK unit 11. Alternatively, pilot signals may be inserted into a location after the modulated signals output from the ASK unit 11. Both the transmitting and receiving sides know which subcarrier positions the pilot signals are located at.
[28] The multiplier 13 multiplies the output data of the DPSK unit 10 by the output signal of the pilot insertion unit 12 and outputs the multiplication result.
[29] FIG. 2 is a constellation diagram of A-DQPSK data in which DPSK and ASK modulation orders are 2.
[30] As shown in FIG. 2, constellation points for the additional transmission data are generated additionally at a constant interval β in the constellation points of DPSK data for the main transmission data.
[31] In FIG. 2, parameters α and β are used to determine a bit error rate of the additional transmission data, except the main transmission data, transmitted through the conventional system and compatibility with the conventional system. According to the simulation results, optimal parameters are preferably α=1.5 and β=l in the terrestrial DMB system. In a case of another digital communication or broadcasting system, it is necessary to set parameters to optimal parameters so as to obtain optimal performance while maintaining compatibility with the conventional system.
[32] In the A-DQPSK system, a pilot for estimating amplitude information has to be periodically or non-periodically transmitted as in a general pilot signal transmission method. In addition, in order to maintain the compatibility with the conventional system, the conventional terrestrial DMB data has to be DQPSK-modulated modulation, while the additional transmission data has to ASK-modulated. At this time, the conventional terrestrial DMB receiver can successfully demodulate data corresponding to a conventional terrestrial DMB service by considering the A-DQPSK modulated signals and the DAQPSK modulated signals as the DQPSK modulated signals.
[33] FIG. 3 is a block diagram illustrating an A-DPSK demodulation apparatus according to an embodiment of the present invention. The shown A-DPSK demodulation apparatus illustrated in FIG. 3 includes a main transmission signal demodulation unit 31 and an additional transmission signal demodulation unit 32.
[34] The main transmission signal demodulation unit 31 outputs the main transmission signal by DPSK-demodulating signals received through a channel and then OFDM- demodulated. The DPSK demodulation is performed by using the conventional demodulation method which uses, for example, a one-symbol delay and a complex conjugate multiplier.
[35] The additional transmission signal demodulation unit 32 includes a pilot extraction unit 321, a channel amplitude estimation unit 322, a pilot removing unit 323, and an ASK demodulation unit 324.
[36] Since the pilot extraction unit 321 knows the locations of the pilot signals, the pilot extraction unit 321 extracts a pilot from a signal which is received through a channel and OFDM-demodulated. The channel amplitude estimation unit 322 performs channel estimation by using the extracted pilot and extracts only amplitude from the estimated channel value. One of conventional channel estimation methods comprising least square estimation and maximum likelihood estimation may be employed as the channel estimation method.
[37] The pilot removing unit 323 removes the pilot signals from the transmission signal into which the pilot signals are inserted. The ASK demodulation unit 324 outputs the additional transmission data by demodulating the signal from which the pilot signals are removed by using the estimated amplitude.
[38] FIG. 4 illustrates simulation results showing receiving performance of a conventional
DQPSK receiver with respect to an A-DQPSK signal according to the present invention, conventional DQPSK and differential amplitude phase shift keying (DAPSK) signals. The simulation is performed with respect to DAB transmission mode 1. A carrier frequency is 200 MHz, a bandwidth is 1.536 MHz, and a frame length is 96 ms. A frame is constructed with 76 OFDM symbols. Each OFDM symbol is constructed with 1,536 subcarriers with an interval of 1 kHz.
[39] As shown in FIG. 4, when the A-DQPSK and DAQPSK techniques are applied, receiving performance of the conventional terrestrial DMB receiver deteriorates by about 3 dB in case that a terminal is moving at 10 km/h speed. When the terminal is moving at 200 km/h, the terrestrial DMB receiver has similar performance to the conventional receiver.
[40] FIG. 5 illustrates the receiving performance of the A-DPSK modulation technique and the DAPSK modulation technique under the same conditions as the case shown in FIG. 4. As shown in FIG. 5, in a mobile receiving environment in which the moving speed of the terminal reaches 200 km/h, the receiving performances of the DAPSK and A-DPSK modulation techniques become largely deteriorated due to interference between subcarriers. In addition, the receiving performance of the DAPSK modulation technique becomes deteriorated more than that of the A-DPSK modulation technique. When the moving speed of the terminal is very high, since a channel change between neighboring OFDM symbols occurs largely, differential demodulation performance become lowered.
[41] As shown in FIGS. 4 and 5, the A-DPSK signal method can improve receiving performance of the terrestrial DMB system in a mobile receiving environment compared with the DAPSK signal method.
[42] The examples shown in FIGS. 4 and 5 are cases applied for increasing a data transmission speed of the terrestrial DMB system. The A-DPSK signal method suggested in the present invention can be applied to various digital communication or broadcasting systems besides the terrestrial DMB system.
[43] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

Claims
[1] An A-DPSK (amplitude-differential phase shift keying) modulation apparatus comprising: a first modulation unit for DPSK (differential phase shift keying) -modulating a first data sequence; a second modulation unit for ASK (amplitude shift keying)-modulating a second data sequence and inserting pilot signals into the ASK-modulated signal; and a multiplier for multiplying outputs of the first and second modulation units and outputting the multiplication result.
[2] The A-DPSK modulation apparatus of claim 1, wherein the pilot signals are periodically or non-periodically inserted into known locations of subcarriers of the ASK-modulated signal.
[3] An A-DPSK (amplitude-differential phase shift keying) demodulation apparatus comprising: a first demodulation unit for receiving an A-DPSK-modulated signal and DPSK- demodulating the received signal; a second demodulation unit for extracting pilot signals from the received signal, removing the extracted pilot signals from the received signal, and ASK- demodulating the pilot signals removed A-DPSK-modulated signal.
[4] The A-DPSK demodulation apparatus of claim 3, wherein the pilot signals are periodically or non-periodically inserted into known locations of subcarriers of the received signal.
[5] The A-DPSK demodulation apparatus of claim 3 or 4, wherein the second demodulation unit includes: a pilot extraction unit for extracting the pilot signals from the received signal; a channel amplitude estimation unit for estimating a channel through which the received signal is transmitted using the extracted pilot signals and outputting amplitudes of the pilot signals from the estimated channel value; a pilot removing unit for removing the pilot signals from the received signal; and an amplitude shift demodulation unit for ASK-demodulating the pilot signals removed received signal using the pilot amplitude estimation result.
[6] An A-DPSK (amplitude-differential phase shift keying) modulation method comprising:
DPSK (differential phase shift keying)-modulating a first data sequence; ASK (amplitude shift keying)-modulating a second data sequence; inserting pilot signals into the ASK-modulated signal; and multiplying the DPSK-modulated signal sequence by the pilot signals inserted ASK-modulated signal sequence.
[7] The A-DPSK modulation method of claim 6, wherein the pilot signals are periodically or non-periodically inserted into known locations of subcarriers of the ASK-modulated signal.
[8] A modulation method comprising: generating a plurality of constellation points with multi-phases having a first amplitude in a constellation diagram by DPSK-modulating a first data sequence; and modulating a second data sequence so as to further generate a plurality of constellation points whose amplitudes are separated from the first amplitude at constant intervals.
[9] The modulation method of claim 8, wherein the second data sequence is ASK-modulated, and wherein pilot signals are periodically or non-periodically inserted into known locations of subcarriers of the ASK-modulated signal.
[10] A demodulation method comprising:
DPSK (differential phase shift keying) -demodulating a received signal which is
A-DPSK modulated; extracting pilot signals from the received signal; estimating a channel through which the received signal is transmitted using the extracted pilot signals and outputting amplitudes of the pilot signals from the estimated channel value; removing the pilot signals with the amplitudes from the received signal; and
ASK-demodulating the received signals with the pilot signals removed.
PCT/KR2007/006259 2006-12-07 2007-12-04 Amplitude-differential phase shift keying modulation apparatus and method WO2008069556A1 (en)

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CN102739591A (en) * 2012-06-29 2012-10-17 东南大学 Multivariate position 3 value MCP-EBPSK (Modified Continue Phase-Extended Binary Phase Shift Keying) modulation and demodulation method
CN103647737A (en) * 2013-12-20 2014-03-19 东南大学 Time-hopping multi-access achieving method for m-ary position phase shift keying (MPPSK) modulation
CN103795665A (en) * 2013-11-15 2014-05-14 上海交通大学 Substrate integrated waveguide interconnection-based quadrature phase shift keying (QPSK) high-speed data transmission system
CN110611633A (en) * 2018-06-14 2019-12-24 大唐移动通信设备有限公司 Method and device for processing 16-amplitude phase keying signal
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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102739591A (en) * 2012-06-29 2012-10-17 东南大学 Multivariate position 3 value MCP-EBPSK (Modified Continue Phase-Extended Binary Phase Shift Keying) modulation and demodulation method
CN102739591B (en) * 2012-06-29 2014-12-17 东南大学 Multivariate position 3 value MCP-EBPSK (Modified Continue Phase-Extended Binary Phase Shift Keying) modulation and demodulation method
CN103795665A (en) * 2013-11-15 2014-05-14 上海交通大学 Substrate integrated waveguide interconnection-based quadrature phase shift keying (QPSK) high-speed data transmission system
CN103647737A (en) * 2013-12-20 2014-03-19 东南大学 Time-hopping multi-access achieving method for m-ary position phase shift keying (MPPSK) modulation
CN103647737B (en) * 2013-12-20 2016-09-21 东南大学 The time hopping modulation implementation method of MPPSK modulation
CN110611633A (en) * 2018-06-14 2019-12-24 大唐移动通信设备有限公司 Method and device for processing 16-amplitude phase keying signal
CN110611633B (en) * 2018-06-14 2021-01-29 大唐移动通信设备有限公司 Method and device for processing 16-amplitude phase keying signal
EP4005169A4 (en) * 2019-07-29 2022-08-03 Telefonaktiebolaget LM Ericsson (publ) Method and apparatus for phase-aided adaptive modulation

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