EP1108305A1 - Procede et dispositif pour adapter un debit binaire de transmission ou une puissance d'emission a la qualite de transmission d'un canal de transmission - Google Patents

Procede et dispositif pour adapter un debit binaire de transmission ou une puissance d'emission a la qualite de transmission d'un canal de transmission

Info

Publication number
EP1108305A1
EP1108305A1 EP99968275A EP99968275A EP1108305A1 EP 1108305 A1 EP1108305 A1 EP 1108305A1 EP 99968275 A EP99968275 A EP 99968275A EP 99968275 A EP99968275 A EP 99968275A EP 1108305 A1 EP1108305 A1 EP 1108305A1
Authority
EP
European Patent Office
Prior art keywords
transmission
channel
data rate
quality
determined
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP99968275A
Other languages
German (de)
English (en)
Inventor
Josef Eichinger
Rüdiger Halfmann
Werner Liegl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
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 Siemens AG filed Critical Siemens AG
Publication of EP1108305A1 publication Critical patent/EP1108305A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/18—TPC being performed according to specific parameters
    • H04W52/26—TPC being performed according to specific parameters using transmission rate or quality of service QoS [Quality of Service]
    • H04W52/265—TPC being performed according to specific parameters using transmission rate or quality of service QoS [Quality of Service] taking into account the quality of service QoS
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
    • H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0009—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the channel coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0015—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the adaptation strategy
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0023—Systems modifying transmission characteristics according to link quality, e.g. power backoff characterised by the signalling
    • H04L1/0025—Transmission of mode-switching indication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/18—TPC being performed according to specific parameters
    • H04W52/26—TPC being performed according to specific parameters using transmission rate or quality of service QoS [Quality of Service]
    • H04W52/267—TPC being performed according to specific parameters using transmission rate or quality of service QoS [Quality of Service] taking into account the information rate

Definitions

  • the invention relates to a method for adapting a transmission data rate or transmission power to the transmission quality of a transmission channel.
  • a message source 1 generates information which is transmitted from a transmitter to a receiver via a transmission channel 4.
  • the properties of the information to be transmitted depend on the message source.
  • Messages to be transmitted can be, for example, an audio signal or a video signal.
  • Analog transmission systems transmit analog signals that were generated by analog message sources directly via the transmission channel using conventional analog modulation methods. Such modulation methods are e.g. the amplitude modulation, the frequency modulation or the
  • Phase modulation In digital transmission systems, the information to be transmitted is converted into a sequence of binary digits. In order to make the best possible use of the capacity of the channel, the message to be transmitted should be represented with as few binary digits as necessary.
  • a source encoder is used, which has the task of converting and encoding the messages to be transmitted in a sequence of signal values so that the channel can transmit them. The source encoder tries to transmit the messages to be transmitted in binary as efficiently as possible Convert digits.
  • the sequence of binary digits generated by the source encoder is transmitted from the channel to the receiver.
  • Such an actual channel can, for example, consist of a
  • Such channels cannot directly transmit the sequence of binary digits from the transmitter. To do this, the sequence of digital information must be converted into m signal values that correspond to the properties of the channel.
  • a digital modulator is part of the channel encoder 3, which additionally comprises a discrete channel encoder in order to provide the information to be transmitted with an error protection adapted to the channel.
  • the transmission channel 4 is not presupposed to work without errors, but it is assumed that a disturbance source 5 changes the transmitted signals with a certain probability during the transmission.
  • Such interference can be, for example, a crosstalk of signals that are transmitted on adjacent channels.
  • the disturbances can also be caused by thermal
  • Noise is generated which is generated in the electronic circuits, such as amplifiers and filters, which are used in the transmitter and the receiver.
  • interference can also be caused by switching and in the case of radio or satellite connections by weather influences such as thunderstorms, hail or snow. Such influences change the transmitted signal and cause errors in the received digital signal sequence.
  • the channel encoder increases the redundancy of the (binary) sequence to be transmitted. With the help of this redundancy added by the transmitter, the receiver is supported in decoding the information-carrying signal sequence. For this purpose, for example, the channel encoder combines a certain number of signals into blocks and adds a number of control signals (in the simplest case a parity bit).
  • increased reliability against channel interference can also be achieved, for example, by increasing the transmission power.
  • the reliability by increasing the erforder ⁇ union channel bandwidth is m usually in verfugbarer bandwidth achieved.
  • the modulator When transmitting always one bit with the data rate R bit / s, the modulator assigns the binary number 0 a signal curve or a signal value (hereinafter referred to only as a signal value) s ⁇ (t) and the binary number 1 a signal value s 2 (t). This transmission of every single bit by the channel encoder is called binary modulation.
  • the digital demodulator processes the (ev. Changed ⁇ changed) in the channel transmitted signal value and assigns to each signal value is a single number to which represents an estimate of the transmitted data symbol (eg binar).
  • the demodulator After receiving a signal in the receiver, the demodulator must decide which of the M possible signal values has been sent. This decision is made in a decision maker (slicer), the decision should be made with minimal probability of error. This decision maker assigns a (usually prepared) reception value to one of the M possible symbol values.
  • the demodulator must decide when processing each received signal whether the bit being transmitted is a zero or a one. In this case the demodulator makes a binary decision. Alternatively, the demodulator can also make a ternary decision, the demodulator deciding for "zero", “one” or “no decision” depending on the quality of the received signal.
  • the decision process of a demodulator can be viewed as quantization, in which binary and ternary decisions are special cases of demodulation that quantizes Q levels, where Q> 2.
  • the demodulator If the transmitted information contains no redundancy, the demodulator must decide in each predetermined time interval which of the M signal values has been transmitted. Contains the transmitted information, however the redundancy, the demodulator reconstructs the original information ⁇ sequence due to the channel coder used by the code and the redundancy of the received data. Depending on the requirements determined by the applications, the channel encoder generates signal blocks that allow the channel decoder to either only determine whether certain faults have occurred (error-recognition coding) or even to correct errors caused by faults (up to a certain maximum number per signal block) (error correcting coding).
  • the error rate represents a measure of the reliability with which messages are transmitted from the sender to the receiver.
  • the error rate indicates the average probability with which a bit error occurs
  • the bit error rate indicates the number of error bits occurring at the receiver divided by the total number of bits received per unit of time.
  • the bit error rate (or symbol error rate when assessing the error frequency of symbols) is the most important quality criterion of a digital transmission system. In general, the probability of error depends on the code properties, the type of signal values used to transmit the information about the channel, the transmission power, the properties of the channel, ie the strength of the noise, the type of interference, etc., and the demodulation and decoding processes.
  • the significance of the bit error rate for digital transmission systems corresponds to that of the signal-to-noise ratio (SNR) of analog transmission systems.
  • SNR signal-to-noise ratio
  • the error rates with which symbols appear at the output of the demodulator or bits at the output of the decoder are dependent on the properties of the transmission medium, ie of the transmission medium. channel, depending on the chosen modulation and coding scheme and on the average power of the transmission signal.
  • the transmission properties of the transmission channel are conventionally determined by transmitting a bit or symbol sequence known to the receiver.
  • the error rate of the channel can be determined in the receiver by means of a target / actual comparison. In this way, the goodness of the current data transmission can be determined.
  • a disadvantage of this method is that only the measurement can be measured extraction process of a possible combination of transmission power, coding and Modula ⁇ . Thus need not be performed for each possible data rate or transmit power of its own measurement of finding an optimum Ubertragungschalrate or transmit power are typically itera m ⁇ used tive method.
  • the object of the invention is to provide an improved method or an improved device for adapting the transmission data rate and / or the transmission power to the transmission channel.
  • This task is for a device with the technical
  • Transmission power m is set as a function of the measured signal-stor distance of the transmission channel.
  • the maximum possible data throughput can be determined by measuring the transmission quality, in particular the signal-stor distance, of the transmission channel and accordingly a transmission / Diffraction data rate specified or the transmitted power are m Depending ⁇ ness minimized by the use Ubertragungschalrate.
  • the Ubertragungssequenz from modulator Ubertragungs- channel demodulator "Online" (ie, during the micro appreciatedtra ⁇ supply) can be independent of a chosen coding ⁇ be measured process and the transmission power and / or the coding method m depending on the required data transmission rate be set so that a predetermined bit or symbol error rate is guaranteed.
  • the measurement of the signal-Stor-distance is a prerequisite to an encoding method defined so that the maximum possible data throughput can be found for a maximum tole ⁇ rierbare error rate and to determine for a fixed transmission rate, the minimum transmission power so that a maximum tolerable error rate is not exceeded.
  • the power of the transmitter can be adapted to the required transmission quality by increasing or reducing the transmission power as a function of a difference between the measured signal-stor distance and the required signal-stor distance.
  • the transmission power can be optimally based on a measurement of the signal-stor distance, that is to say the lowest possible transmission power while at the same time guaranteeing the quality requirements and Compliance with the required transmission rate can be adapted to the selected transmission method and the existing transmission channel, ie minimized.
  • the Stor emissions are minimized and at the same réelleska ⁇ is capacity of neighboring systems that operate on the same frequency ⁇ band, increases.
  • Fig. 2 shows the structure of an inventive shaped Ubertragungs- system for adapting the data rate and the Modulationsver ⁇ driving to the transmission medium by receiver-end signal-Stor-distance measurement,
  • FIG 3 shows the structure of a transmission system according to the invention for adapting the transmission data rate, the modulation method and the transmission power to the transmission medium by means of the receiver-side signal-Stor distance measurement and
  • FIG. 4 shows a diagram to illustrate the “power control” for setting a transmission power as a function of a measured and a used transmission quality.
  • information is between a news source (sender) and one
  • Such a device located between the transmitter and the receiver, is generally referred to as a channel.
  • the data to be transferred m Converted code words, which are adapted to the transmission properties of the message channel, in order to secure the data to be transmitted, inter alia, against transmission errors.
  • a character which is generally referred to as a symbol in the signal space or channel symbol, is assigned in the transmitter by means of a reversibly unique functional assignment of a bit sequence.
  • This symbol is then mapped to a signal curve assigned to this symbol (hereinafter referred to as signal value).
  • signal value The functional assignment of one or more symbols to a bit sequence in the transmitter is called coding or mapping, the mapping of one or more such symbols to a signal value is called modulation.
  • This picture sequence is reversed in the receiver.
  • the allocation that is a received signal to a symbol due to Distortion ⁇ gene or superimposed interference of the channel is not m the control can be performed without error, prepares the decoded more tion, that is, the transfer of a detected symbol, the corresponding bit sequence m with ease .
  • FIG. 2 the construction of a transmission system is ones shown, provides that Nals sets a desired data rate to determine the quality of Ubertragungska ⁇ .
  • Digital information in particular a bit sequence 13 is transmitted from a transmitter 10 via a transmission channel 11 to a receiver 12, which outputs the received digital information, in particular the bit sequence 25.
  • the channel encoder 14 of the transmitter 10 contains a digital channel encoder 50, a bit / symbol converter 15 and a modulator 17.
  • the digital channel encoder 50 adds redundancy to the incoming bit stream 13.
  • the coded bit stream 51 thus formed is converted into a symbol sequence 16 in the bit / symbol converter 15 m, which in turn is reversibly and uniquely mapped onto a signal curve or signal values 18 by a modulator 17.
  • the signal values 18 are transmitted to the receiver 12 via the transmission channel 11.
  • the received signal values 19 are first processed by an analog and optional digital signal processing unit, which could include, for example, a reception amplifier, an A / D conversion and an equalizer.
  • the so processed signal value 21 is then a slicer or decision leads 22 supplied ⁇ , of each received signal value? 21 assigns a symbol 23.
  • the / bit converter 24 symbol of the channel decoder 20 arranged each detected symbol or each detected Symbolse acid sequence 23 according to the selected method Mappmg an encoded digital information and an encoded bit sequence to 53 from which by means of the digital channel Decoder 52 the digital information or the bit stream 25 is derived according to the selected coding method.
  • the decision maker (slicer) 22 is a fundamental component of every demodulator. Such a decision maker assigns the symbol or symbols that was most likely to be transmitted to a received value prepared in the rule. Since the set of input values of the decision maker does not generally correspond to the "valid" signal values of the transmitter due to interference or distortion of the transmission channel m, ie the signal values that are assigned to the symbols to be transmitted, the input signal 21 and the output 23 of the decision of the decider ⁇ applied signal-Stor-distance passage 28 regardless of the encoding and Mappmg algorithm are determined.
  • a receiver according to the invention has a device 27 for measuring the signal-to-noise ratio (signal-to-noise ratio SNR) of the information transmitted via the transmission channel 11.
  • a signal value 60 is assigned to each detected symbol in the demodulator on the receiver side, which the decision-maker input in the demodulator had received if the signal curve or signal value corresponding to the detected symbol was undistorted would have been transferred.
  • a hypothetical input signal is generated which corresponds to the detected symbol values and does not contain any signal values with channel distortions and interference.
  • This reference signal corresponds - as long as the decision maker does not detect any wrong symbols - to the original signal on the transmitter side.
  • the interference signal can be obtained by subtracting this reference signal from the processed receiver signal 21.
  • the average power of this reference signal formed in this way corresponds to the average power of the received, undisturbed signal component.
  • the average power of the signal at the decision input corresponds to the total power of the received interference and signal component.
  • the interference power is calculated with the aid of the previously calculated undisturbed signal component.
  • the signal-to-interference distance (SNR) results as a measure of the transmission quality of the transmission channel.
  • the signal-to-memory distance 28 also referred to as signal-to-noise ratio
  • the signal-stor distance thus qualifies the transmission properties of the channel and the currently selected modulation or demodulation method, regardless of the coding or mapping method selected.
  • Over a Measuring of the signal-Stor-distance 28 of a Ubertragungs ⁇ channel 11 can thus be the coding or the Mappmg method of the current modulation / demodulation method so Festge ⁇ specifies that a desired data throughput can be set for a still tolerable error rate .
  • the device 29 determines a dependency on the preferably m decibel (dB) determined signal-to-storage distance 28 according to a known connection, a coding and mapping method or a maximum transmission data rate 30 for the current modulation and demodulation method, which at the existing signal-stor distance 28 enables a maximum data throughput.
  • dB decibel
  • a coding scheme (code 1, code 2 ... Code 6) and Mappmg-Sche a (Map. 1 ... Map. 6) are selected, which, given the actual situation, enables a maximum data throughput for the current modulation / demodulation method with a predetermined reliability.
  • the device 29 can be arranged both in the receiver 12 and in the transmitter 10. In any case, either the determined signal-to-storage distance 28 or the determined maximum transmission data rate or the selected coding and mapping method 30 must be transmitted to the transmitter via a data connection 31.
  • the information about the coding and mapping method, with which a maximum transmission data rate 30 can be achieved for the current modulation / demodulation method, is fed to a control device 33 in the transmitter.
  • These control emcardi selected on the basis of the maximum possible data ⁇ transmission rate and the digital to transmission information 13 are each required data transmission rate 32, a data transmission rate 34 tatsumble Lich used ⁇ from that to be fixed on en encoding, Mappmg- and modulation scheme is to be implemented.
  • This information data rate on the one hand and / or coding, Mappmg- and modulation method other ⁇ hand - is both the corresponding components of the channel encoder 14 of the transmitter 10, such as encoder 50, bit / symbol converter 15 and modulator 17, as well as a Data link 35 is fed to the corresponding components of the channel decoder 20 of the receiver 12, such as demodulator 55, symbol / bit converter 24 and decoder 52.
  • the operation of the inventive Vorrich ⁇ processing at startup of the transmission system will be described.
  • the measurement of a transmission system is conveniently carried out with the lowest possible transmission data rate (based on the respective modulation method) and with the maximum possible transmission power. In this way, a low symbol error rate is guaranteed, the prerequisite for a high quality of a receiver
  • Signal-Stor distance measurement is.
  • the generally used adaptive methods for signal processing have the shortest settling times and the largest possible system range is achieved in relation to a maximum permissible error rate.
  • Coding and mapping method which allows a maximum possible transmission data rate for the transmission channel (and the modulation method currently used), then only a single measurement is required. Should be made possible if the desired data rate over different Modula ⁇ tion process, it must be a measuring performed for each mög ⁇ Liche modulation scheme.
  • Fig. 2 an embodiment is described in which determination of the signal-stor distance on the receiver side determines the maximum possible transmission data rate and transmits it to the transmitting side, which in turn determines an actually used transmission data rate based on the desired and the maximum possible transmission data rate and forwards it to the corresponding components in the transmitter and receiver .
  • FIG. 3 which additionally controls the output power of the transmitter.
  • Fig. 3 has the same devices as m Fig. 2 on ⁇ , these are provided with the same reference numerals.
  • the transmitter has a device 41 which, like the device 29 in FIG. 2, determines a coding scheme or a maximum transmission data rate of the transmission channel 11.
  • the device 41 is also supplied with the data rate 32 required for the transmission of the digital information 13.
  • a coding or mapping and modulation method with an actual transmission data rate 34 is selected. This selected transmission data rate 34 is, as in the embodiment described with reference to FIG. 2, forwarded to the channel encoder 14 and the channel decoder 20.
  • the signal values 44 generated by the modulator 14 are additionally sent in the transmitter 10 to a device 43 for regulating the Transmission power forwarded.
  • the signal generated by the device 43 45 is then transmitted via the Ubertragungska ⁇ nal. 11
  • the minimum transmission power required for transmission is also determined by the device 41.
  • the transmission power is determined is eistungssignal 42 Ubertragungssignalverstarker the leads 43 applied ⁇ a Sendel ⁇ .
  • a measured transmission quality of the transmission channel 46 and 11 of a transmission quality 47 (tenrate with a Ubertragungsda ⁇ 34 and having a certain maximum allowable error rate) to the selected coding and modulation method Mappmg- and corresponds to a Adaptation of the transmission power of the transmission signal amplifier 43 causes. This means that if the determined transmission signal quality of the transmission channel 46 is above the required transmission quality 47, the transmission power is reduced accordingly. If the required transmission quality 47 is above the transmission quality of the transmitter, the transmission power must be increased.
  • the difference between the measured signal-to-storage distance 46 and that required to implement a specific transmission data rate provides
  • Such a system according to the invention for adapting a transmission system to the transmission channel used is particularly suitable for use with the "asymmetric digital subscriber lme" technology.
  • This so-called ADSL technology makes as well as other XDSL technologies zubrmger tauglicn for data-intensive applications ago ⁇ tional copper telephone lines than Hochgeschwmdtechniks-. Gleichzei ⁇ tig remains the availability of the usual telephone voice ⁇ services on the same line received.
  • Such technologies provide data rates that exceed ISDN, for example, many times over. This removes the restrictions of the existing public information network, which was previously only suitable for the transmission of speech, text and graphics with a low resolution. With such technologies, the conventional copper cable telephone network becomes a powerful system that is suitable for the transmission of multimedia content to all households.
  • the noise component increases not only with increasing length but also due to crosstalk from neighboring lines.
  • the transmission system can automatically measure and adapt to the quality of the existing transmission line.

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  • Engineering & Computer Science (AREA)
  • Quality & Reliability (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Detection And Prevention Of Errors In Transmission (AREA)

Abstract

Le but de l'invention est d'adapter un débit binaire de transmission à un canal de transmission existant. Dans ce but, la puissance d'émission et/ou le procédé de codage sont choisis de manière qu'un débit binaire maximal possible de transmission ou une puissance d'émission minimale puissent être utilisés, en fonction de la qualité de transmission du canal de transmission.
EP99968275A 1998-08-28 1999-08-27 Procede et dispositif pour adapter un debit binaire de transmission ou une puissance d'emission a la qualite de transmission d'un canal de transmission Withdrawn EP1108305A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19839306 1998-08-28
DE19839306 1998-08-28
PCT/EP1999/006309 WO2000013362A1 (fr) 1998-08-28 1999-08-27 Procede et dispositif pour adapter un debit binaire de transmission ou une puissance d'emission a la qualite de transmission d'un canal de transmission

Publications (1)

Publication Number Publication Date
EP1108305A1 true EP1108305A1 (fr) 2001-06-20

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP99968275A Withdrawn EP1108305A1 (fr) 1998-08-28 1999-08-27 Procede et dispositif pour adapter un debit binaire de transmission ou une puissance d'emission a la qualite de transmission d'un canal de transmission

Country Status (3)

Country Link
EP (1) EP1108305A1 (fr)
CN (1) CN1325573A (fr)
WO (1) WO2000013362A1 (fr)

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KR100605973B1 (ko) * 2000-06-27 2006-07-28 삼성전자주식회사 이동통신 시스템의 링크적응 방법 및 장치
EP2293452B1 (fr) * 2000-07-05 2012-06-06 LG ELectronics INC. Procédé de poinçonnage d'un bloc de données turbo codées
WO2002013447A2 (fr) * 2000-07-21 2002-02-14 Aperto Networks, Inc. Systeme de telecommunication integre (ii) point a multipoint auto-optimisant a parametres multiples/a variables multiples
US6636488B1 (en) 2000-10-11 2003-10-21 Aperto Networks, Inc. Automatic retransmission and error recovery for packet oriented point-to-multipoint communication
US8634481B1 (en) * 2000-11-16 2014-01-21 Alcatel Lucent Feedback technique for wireless systems with multiple transmit and receive antennas
EP1160996A1 (fr) * 2001-02-02 2001-12-05 Siemens Aktiengesellschaft Procédé, dispositif et système de radio mobile pour le contrôle des charactéristiques de transmission d'un premier transmetteur
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Publication number Publication date
CN1325573A (zh) 2001-12-05
WO2000013362A1 (fr) 2000-03-09

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