WO2007015494A1 - Appareil de communication ofdm - Google Patents

Appareil de communication ofdm Download PDF

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Publication number
WO2007015494A1
WO2007015494A1 PCT/JP2006/315235 JP2006315235W WO2007015494A1 WO 2007015494 A1 WO2007015494 A1 WO 2007015494A1 JP 2006315235 W JP2006315235 W JP 2006315235W WO 2007015494 A1 WO2007015494 A1 WO 2007015494A1
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WO
WIPO (PCT)
Prior art keywords
ofdm
length
cyclic prefix
ofdm symbol
channel
Prior art date
Application number
PCT/JP2006/315235
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English (en)
Japanese (ja)
Inventor
Haitao Li
Jifeng Li
Original Assignee
Matsushita Electric Industrial Co., Ltd.
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
Application filed by Matsushita Electric Industrial Co., Ltd. filed Critical Matsushita Electric Industrial Co., Ltd.
Publication of WO2007015494A1 publication Critical patent/WO2007015494A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2602—Signal structure
    • H04L27/2605—Symbol extensions, e.g. Zero Tail, Unique Word [UW]
    • H04L27/2607—Cyclic extensions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2626—Arrangements specific to the transmitter only
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/16—Code allocation
    • H04J13/18—Allocation of orthogonal codes

Definitions

  • the present invention relates to an OFDM communication apparatus, and more particularly to a transmission system such as a wireless local area network, mobile communication, and terrestrial digital broadcasting! It relates to OFDM communication equipment that is used.
  • next generation wireless communication system new technology will be adopted for its physical structure and media access control power to the network.
  • OFDM orthogonal frequency division multiplexing
  • OFDM In OFDM, a channel is divided into a plurality of mutually orthogonal subchannels in the frequency domain. Thus, the broadband selective channel becomes a relatively flat subchannel. Also, in OFDM, inter symbol interference (ISI) can be significantly reduced by inserting a CP (Cyclic Prefix) as a guard interval (GI) between each OFDM symbol. it can. For this reason, OFDM has already been successfully applied to systems such as ADSL, VDSL, DVB, and WLAN, which are already highly multi-pathable, and OFDM is the core technology for next-generation wireless transmission systems.
  • ISI inter symbol interference
  • GI guard interval
  • the ISI that occurs when a multipath channel is delayed and spread can be reduced using CP.
  • the CP length (CP duration) is usually set to a fixed length that is larger than the maximum delay spread time of the channel and is 2 to 4 times the RMS (Root Mean Square) value of the delay spread.
  • the RMS value of delay spread is about 35 ns in an indoor environment such as an office, whereas the RMS value of delay spread is 300 ns in a factory environment. . Therefore, if the CP length is designed in advance assuming an indoor environment such as an office, when the user equipment (User Equipment: UE) enters a place such as a factory, the CP length becomes insufficient and severe ISI occurs. On the other hand, if the CP length is designed in advance in an environment such as a factory, when the user terminal enters a place such as an office, a surplus in the CP length occurs, and extra power is consumed.
  • UE User Equipment
  • Patent Document 1 discloses adjusting the CP length based on a signal sample.
  • Patent Document 2 discloses changing the CP length and the carrier period in an OFDM system that transmits a television signal.
  • Patent Document 3 discloses that the CP length is determined based on the correlation value between the N samples at the CP end and the N samples at the end of the effective symbol.
  • Patent Document 4 discloses that the minimum CP length for canceling ISI is calculated based on the channel quality situation.
  • FIG. 5 shows an example of the operation flow of the conventional OFDM system.
  • the receiving side estimates the channel quality from the received signal.
  • the minimum CP length for canceling ISI is calculated according to the channel quality.
  • the CP length is adjusted to the length calculated in step S502.
  • Patent Document 1 US Pat. No. 6,535,550 Specification
  • Patent Document 2 European Patent No. 1439679 Specification
  • Patent Document 3 Japanese Patent Laid-Open No. 2003-152670
  • Patent Document 4 European Patent No. 1014639
  • An object of the present invention is to improve spectral efficiency and data transmission efficiency.
  • the OFDM communication apparatus of the present invention includes a generating means for generating an OFDM symbol, an OFDM symbol, It adopts a configuration comprising an inserting means for inserting a cyclic prefix between the symbols and a control means for controlling the cyclic prefix length and the OFDM symbol length according to the channel quality.
  • FIG. 2 is a block diagram showing an OFDM system according to an embodiment of the present invention.
  • FIG. 3 is a diagram showing a configuration of an OFDM symbol used in an OFDM system according to an embodiment of the present invention.
  • FIG. 4 is an operation flow diagram of an OFDM system according to an embodiment of the present invention.
  • the first channel environment there are two channel environments, the first channel environment and the second channel environment.
  • the maximum RMS value of the delay spread in the first channel environment is ⁇
  • the maximum delay spread in the second channel environment is Assume that the RMS value is ⁇ (where ⁇ ⁇ ).
  • the CP length is 1, as shown in Fig. 1A. Meanwhile, ⁇
  • the CP length is 1 as shown in Figure 1B. That is, 1
  • the CP length is adaptively adjusted according to changes in the channel environment, and the first
  • Data is transmitted when the CP length is changed to 1 in the second channel environment.
  • Subcarriers can be increased by 1 minute. Therefore, in the present invention, resources are wasted.
  • the OFDM symbol length is increased by the CP length reduction to improve the data transmission rate.
  • FIG. 2 is a block diagram of an OFDM system according to an embodiment of the present invention.
  • an IDFT (Inverse Discrete Fourier Transform) unit 201 inputs the input baseband data stream to a plurality of subcarriers and performs IDFT to generate an OFDM symbol. .
  • CP insertion section 202 inserts a CP as a GI between all OFDM symbols.
  • Transmission RF section 203 modulates the OFDM symbol after CP insertion into a radio frequency band and transmits it from antenna 204.
  • the reception RF unit 207 down-converts the signal received via the antenna 206 into a baseband signal.
  • CP removing section 208 removes baseband signal power CP.
  • a DFT (Discrete Fourier Transform) unit 209 performs DFT on the OFDM symbol after CP removal, and demodulates the data stream of each subcarrier.
  • Channel quality estimation section 210 estimates the channel delay spread RMS value, user terminal transmission rate, and Doppler frequency shift as channel quality using the pilot signal of the received signal, The estimated information is output to the control unit 211 as control information.
  • Control unit 211 outputs this control information to CP removal unit 208 and also transmits it to control unit 205 on the base station side via a feedback channel. Further, the control unit 211 controls processing of the CP removal unit 208 and the DFT unit 209.
  • control unit 205 adjusts the CP length according to the control information.
  • the number of data subcarriers, that is, the OFDM symbol length is adjusted.
  • the base station transmitting side
  • an IFFT Inverse Fast Fourier Transfer m
  • the user terminal receiving side
  • an FFT Fast t Fourier Transform
  • the CP length is set using the RMS value of the delay spread estimated in the stationary multipath channel environment.
  • Channel bandwidth is B
  • number of system subcarriers is N
  • number of modulation subcarriers number of data subcarriers of IFFT is N (mod
  • N Number of carriers (number of CP subcarriers) is N, modulation constellation stage is C, subcarrier
  • the period is T. Therefore, the OFDM symbol period (CP length + OFDM symbol length) is T
  • Equation (1) shows the spectral efficiency of the OFDM system. Equation (1) shows the transmission rate of one OFDM symbol block (CP + OFDM symbol).
  • equation (2) becomes equation (3).
  • ⁇ 1 ⁇ 4 is set to reduce the overhead of CP.
  • the CP length is 800 ns and the OFDM symbol period is 4 / z s, 1Z5, that is, 1/5.
  • FIGS. 3A and 3B are diagrams showing configurations of OFDM symbols in the OFDM system shown in FIG.
  • the OFDM symbol period that is, the total number of subcarriers
  • the CP length that is, the number of CP subcarriers
  • the OFDM symbol length that is, the data subcarriers. The number varies with the line quality.
  • FIG. 4 is a flowchart showing the operation of the OFDM system according to one embodiment of the present invention.
  • the channel quality estimation unit 210 of the user terminal uses a pilot sequence transmitted from the base station (transmitting side) based on the prior art, for example, Osvaldo Simeone , Yeheskel Bar-Ness, Umberto Spagnolini, Pilot-based chan nel estimation for OFDM systems by tracking the delay- subspace ", IEEE Trans activations on Wireless Communications, vol.3, no.l, Jan 2004 pp.315—325, Also proposed in i3 ⁇ 4 Pilot ton e selection for channel estimation in a mobile OFDM system “Negi, R .; shi loffi, J. Consumer Electronics, IEEE Transactions on Volume 44, Issue 3, Aug 1998 Page (s): 1122 -1128 In this way, the RMS value of the maximum delay spread of the multipath channel is estimated.
  • a pilot sequence transmitted from the base station transmitting side
  • step S 402 user terminal control section 211 and base station control section 205 set the CP length within a range of 2 to 4 times the RMS value of the maximum delay spread.
  • step S403 the lower limit (equation (4)) of the OFDM symbol period is determined based on the ratio between the control unit 205 force CP length of the base station and the OFDM symbol period.
  • step S404 the channel quality estimation unit 210 of the user terminal (receiving side) Estimate the maximum Doppler frequency shift of the channel using a no- til sequence where the ground station (transmitter) force is also transmitted.
  • step S405 the control unit 213 of the base station determines the upper limit of the OFDM symbol period (Equation (7)) based on the ratio of the maximum carrier frequency shift according to the system and the maximum Doppler frequency shift of the channel. ) Is confirmed.
  • step S406 the control unit 213 of the base station determines the OFDM symbol period based on the upper and lower limits of the OFDM symbol period.
  • step S407 the total number of subcarriers, the number of CP subcarriers, and the number of data subcarriers are calculated based on the control unit 213 power channel bandwidth, OFDM symbol period, and bandwidth efficiency coefficient of the base station.
  • step S408 user terminal control section 211 and base station control section 20
  • the RMS value of the maximum delay spread and the maximum Doppler frequency shift that are estimated as the channel quality.
  • the number of CP subcarriers and the number of data subcarriers are adjusted based on the channel quality indicated by these parameters.
  • the CP length that is, the number of CP subcarriers
  • the OFDM symbol length that is, the number of data subcarriers
  • the OFDM symbol length is also adjusted based on the channel quality.
  • the OFDM communication apparatus of the present invention is suitable for a communication system that requires high transmission efficiency in an environment in which channel quality changes, particularly a mobile communication system.

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

Abstract

L’invention concerne un appareil de communication OFDM capable d’améliorer l’efficacité de spectre et l’efficacité de transmission de données du système OFDM. Dans cet appareil, une pièce IDFT (201) génère des symboles OFDM. Une pièce d’insertion de CP (202) insère un préfixe cyclique parmi les symboles OFDM. Une pièce RF de transport (203) module les symboles OFDM, parmi lesquels le préfixe cyclique a été introduit, en une bande de fréquence radio. Une antenne (204) transmet le signal modulé. Une pièce de commande (205) contrôle la longueur du préfixe cyclique et la longueur des symboles OFDM selon la qualité du réseau. Une antenne (206) reçoit le signal, qui est ensuite converti vers le bas par une pièce RF reçue (207) en signal de bande de base. Une pièce d’enlèvement de CP (208) retire le CP du signal de bande de base. Une pièce DFT (209) réalise un DFT pour démoduler les chaînes de données des sous-porteuses respectives. Une pièce d’évaluation de qualité du réseau (210) utilise un signal pilote reçu pour évaluer, comme qualités de réseau, le décalage de fréquence Doppler et la valeur RMS d’étalement de temporisation d’un canal. Une pièce de commande (211) contrôle les traitements de la pièce d’enlèvement de CP (208) et de la pièce DFT (209).
PCT/JP2006/315235 2005-08-02 2006-08-01 Appareil de communication ofdm WO2007015494A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN200510088291.5 2005-08-02
CNA2005100882915A CN1909534A (zh) 2005-08-02 2005-08-02 可重构ofdm系统及其发送和接收操作方法

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008517533A (ja) * 2004-10-14 2008-05-22 クゥアルコム・フラリオン・テクノロジーズ、インコーポレイテッド 無線通信システムにおいて帯域幅割当を調節する方法及び装置
FR2932933A1 (fr) * 2008-06-18 2009-12-25 Canon Kk Procedes et dispositifs de transmission et de reception de donnees
US7969858B2 (en) 2004-10-14 2011-06-28 Qualcomm Incorporated Wireless terminal methods and apparatus for use in wireless communications systems supporting different size frequency bands
JP2011188247A (ja) * 2010-03-09 2011-09-22 Kddi Corp 直交周波数分割多重通信装置及び方法
WO2016068072A1 (fr) * 2014-10-31 2016-05-06 三菱電機株式会社 Système de communications
WO2017219215A1 (fr) * 2016-06-20 2017-12-28 华为技术有限公司 Procédé et appareil de transmission de symbole ofdm

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CN101282320B (zh) * 2007-04-03 2013-02-27 中兴通讯股份有限公司 一种基于ofdm技术的宽带无线通信系统带宽扩展方法
CN101383799B (zh) * 2007-09-04 2014-07-16 南开大学 一种实现ofdm系统同步、信道估计和降低峰均比的方法
CN101616113B (zh) * 2008-06-24 2012-06-06 展讯通信（上海）有限公司 基于子带的发射方法及其设备
CN101651647B (zh) * 2008-08-12 2011-12-28 清华大学 时域同步正交频分复用系统中的cp-ofdm信号重构方法及装置
WO2017219320A1 (fr) * 2016-06-23 2017-12-28 华为技术有限公司 Procédé et dispositif pour une configuration de forme d'onde et une indication de forme d'onde
US10715392B2 (en) 2016-09-29 2020-07-14 Qualcomm Incorporated Adaptive scalable numerology for high speed train scenarios
CN113660068B (zh) * 2021-07-08 2022-11-01 南京邮电大学 一种otfs系统中多用户上行动态导频分配方法及系统
CN115913863A (zh) * 2022-12-02 2023-04-04 深圳市汇川技术股份有限公司 Ofdm波形参数集的获取方法、装置、终端以及介质

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002345035A (ja) * 2001-05-16 2002-11-29 Matsushita Electric Ind Co Ltd 無線基地局装置及び通信端末装置
WO2005004428A1 (fr) * 2003-06-27 2005-01-13 Intel Corporation Intervalle de garde adaptative dans des systemes de multipexage frequentiel optique
JP2005150850A (ja) * 2003-11-11 2005-06-09 Ntt Docomo Inc Ｏｆｄｍ送信機及びｏｆｄｍ受信機

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002345035A (ja) * 2001-05-16 2002-11-29 Matsushita Electric Ind Co Ltd 無線基地局装置及び通信端末装置
WO2005004428A1 (fr) * 2003-06-27 2005-01-13 Intel Corporation Intervalle de garde adaptative dans des systemes de multipexage frequentiel optique
JP2005150850A (ja) * 2003-11-11 2005-06-09 Ntt Docomo Inc Ｏｆｄｍ送信機及びｏｆｄｍ受信機

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008517533A (ja) * 2004-10-14 2008-05-22 クゥアルコム・フラリオン・テクノロジーズ、インコーポレイテッド 無線通信システムにおいて帯域幅割当を調節する方法及び装置
US7969858B2 (en) 2004-10-14 2011-06-28 Qualcomm Incorporated Wireless terminal methods and apparatus for use in wireless communications systems supporting different size frequency bands
FR2932933A1 (fr) * 2008-06-18 2009-12-25 Canon Kk Procedes et dispositifs de transmission et de reception de donnees
JP2011188247A (ja) * 2010-03-09 2011-09-22 Kddi Corp 直交周波数分割多重通信装置及び方法
WO2016068072A1 (fr) * 2014-10-31 2016-05-06 三菱電機株式会社 Système de communications
JP2020043609A (ja) * 2014-10-31 2020-03-19 三菱電機株式会社 通信システム
US10674514B2 (en) 2014-10-31 2020-06-02 Mitsubishi Electric Corporation Communication system
US11006427B2 (en) 2014-10-31 2021-05-11 Mitsubishi Electric Corporation Communication system, base station, and communication terminal for controlling interference from neighboring cells
WO2017219215A1 (fr) * 2016-06-20 2017-12-28 华为技术有限公司 Procédé et appareil de transmission de symbole ofdm
CN109156019A (zh) * 2016-06-20 2019-01-04 华为技术有限公司 一种ofdm符号传输方法及装置
CN109156019B (zh) * 2016-06-20 2020-09-29 华为技术有限公司 一种ofdm符号传输方法及装置

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