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EP1066707A1 - Synchronisation de trame dans des systemes de transmission a porteuses multiples - Google Patents

Synchronisation de trame dans des systemes de transmission a porteuses multiples

Info

Publication number
EP1066707A1
EP1066707A1 EP99922038A EP99922038A EP1066707A1 EP 1066707 A1 EP1066707 A1 EP 1066707A1 EP 99922038 A EP99922038 A EP 99922038A EP 99922038 A EP99922038 A EP 99922038A EP 1066707 A1 EP1066707 A1 EP 1066707A1
Authority
EP
European Patent Office
Prior art keywords
signal
synchronization signal
frame synchronization
sub
frame
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Withdrawn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
EP99922038A
Other languages
German (de)
English (en)
Inventor
Markus Radimirsch
Karsten Brueninghaus
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP1066707A1 publication Critical patent/EP1066707A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. Transmission Power Control [TPC] or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0212—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is leader and terminal is follower
    • H04W52/0216—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is leader and terminal is follower using a pre-established activity schedule, e.g. traffic indication frame
    • 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
    • H04L27/261—Details of reference signals
    • H04L27/2613—Structure of the reference signals
    • 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
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2656—Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation
    • 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
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2675—Pilot or known symbols
    • 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
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • 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
    • H04L5/14—Two-way operation using the same type of signal, i.e. duplex
    • H04L5/1469—Two-way operation using the same type of signal, i.e. duplex using time-sharing
    • H04L5/1484—Two-way operation using the same type of signal, i.e. duplex using time-sharing operating bytewise
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/16—Circuits
    • H04B1/1607—Supply circuits
    • H04B1/1615—Switching on; Switching off, e.g. remotely
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • the invention relates to a method for the digital transmission of data in a wireless communication network in which controlling communication from a master station to all subscribers ("downlink") takes place within a defined bandwidth of a channel with the aid of a defined signal frame and the beginning of the signal frame is identified by a special frame synchronization signal that can be detected by the participants.
  • the invention further relates to a receiving device for receiving data transmitted according to the aforementioned method.
  • the zero symbol is used, ie there is no or only one 2 very low power sent out. In such pure distribution services, the zero symbol is unique and therefore the detection in the receiver is simple and unambiguous.
  • the zero symbol suitable for the pure distribution services for the frame synchronization is not clear, because before the start of the transmission - transmission from the base station into the transmission channel
  • Downlink Downlink
  • Uplink Uplink
  • TDD time division duplex multi-carrier transmission system
  • the invention is based on the problem of enabling simple recognition of the beginning of the frame, that is to say in particular the beginning of a downlink phase.
  • the method of the type mentioned at the outset is characterized in that an occupancy of at least a portion of the bandwidth with transmit signals and non-occupancy of at least a complementary portion of the bandwidth with transmit signals are used as the frame synchronization signal.
  • the method according to the invention thus provides for a frame transmission in which a special frequency pattern is transmitted at the beginning of each transmitter frame and is detected in the receiving device.
  • the frequency pattern consists of a defined occupancy of at least a partial area of the bandwidth with transmit signals and non-occupancy of at least one complementary partial area of the bandwidth with transmit signals.
  • one half of the bandwidth is occupied by transmission signals and the other half of the bandwidth is free of transmitter signals.
  • Such a pattern can be generated very easily in an OFDM system if the upper or lower N / 2 subcarrier amplitudes of the N available subcarriers are set to zero.
  • the frame synchronization signal according to the invention can be detected according to the invention in a receiving device with a detection device which has a filter arrangement for dividing the intermediate frequency band into partial areas and a comparison device for comparing the received transmission energy in the partial areas.
  • a receiving device with a detection device which has a filter arrangement for dividing the intermediate frequency band into partial areas and a comparison device for comparing the received transmission energy in the partial areas.
  • Such training of the reception 4 devices is possible with little hardware and can be easily optimized with regard to the required electrical power.
  • the receiving device does not have to carry out complex multiplication functions continuously, as in correlation technology, in order to be able to recognize a frame synchronization signal.
  • the receiving device Rather, it is possible in the receiving device according to the invention to operate a power supply of the receiving device in a power-saving mode and to switch to a full operating state depending on the detection of the frame synchronization signal by the detection device if the full electrical energy for the evaluation of the downlink signal is within of the signal frame is required.
  • the phase and amplitude of the N / 2 subcarriers used for the transmission signals are selected so that, on the one hand, the energy is distributed as evenly as possible over all occupied subcarriers, in order to increase sensitivity to frequency-selective interference in radio - to minimize channel, and on the other hand the resulting
  • Time signal has an envelope that is as constant as possible in order to avoid problems with non-linear transmission amplifiers.
  • the frame synchronization signal designed in accordance with the invention is unambiguous for the systems to be considered, since all other symbols have a uniform power distribution over the subcarriers used. This also applies to the zero symbol. Accordingly, by evaluating the power difference in the
  • Frame synchronization signal can be detected.
  • the performance difference can be evaluated analog or digital.
  • the master station emitting the frame synchronization signal according to the invention can regularly be a base station of a mobile radio network. However, it is also possible to permanently or temporarily assign a master function to a user in a network in which the users communicate directly with one another, ie not via a base station, so that this user then represents the master station in the sense of the invention.
  • Figure 1 an example of a data structure in a method according to the invention
  • Figure 2 an example of a signal structure of a downlink signal
  • Figure 3 - a schematic representation of a frame synchronization signal according to the invention for an OFDM transmission
  • Figure 4 - a schematic diagram for the construction of a receiver for OFDM signals
  • FIG. 5 shows a block diagram of a detection circuit for recognizing the frame synchronization signal according to the invention
  • Figure 6 - a variation of the detection circuit according to Figure 5 for the additional detection of a zero signal
  • Figure 7 - a schematic representation of a first embodiment of an evaluation circuit for the frame synchronization signal
  • Figure 8 - a second embodiment of an evaluation circuit for the frame synchronization signal
  • Figure 9 - a third embodiment of an evaluation circuit for the frame synchronization signal 7
  • FIG. 10 another embodiment of a frame synchronization signal according to the invention
  • Figure 1 shows that for communication between a base station and a large number of communication participants, for example in a mobile radio network, a signal frame 1 from a downlink phase 2, in the downlink signals DS and DC from the base station via the wireless transmission channel to the participants are sent, and there is an uplink phase 3 in which uplink signals UC and US are transmitted from subscribers to the base station via the transmission channel.
  • Figure 1 shows before the start of the downlink phase 2 and the uplink phase 3 short transmission-free intervals 4, which result from the switching of the devices between transmission and reception mode (transceiver turn-around interval). These intervals, which have no transmission energy, result in an ambiguity of zero signals which are otherwise used as a frame synchronization signal.
  • the organization of the communication on the transmission channel is carried out by the base station
  • FIG. 2 shows details of the downlink signals in the downlink phase 2, which follows the switchover interval 4.
  • the downlink signal in the downlink period 2 begins with a frame synchronization signal 5 that 8 can be designed according to the invention in accordance with the exemplary embodiments explained in more detail below.
  • a preamble 6 and two OFDM symbols 7 for fine synchronization then follow. This is followed by data packets 8 in the number required in each case, which results in the variable length of the downlink phase 2.
  • FIG. 3 An embodiment of a frame synchronization signal 5 is shown in Figure 3.
  • the abscissa shows N frequencies for subcarriers of an OFDM signal in discrete equal intervals, of which there are N / 2 subcarriers on the positive and on the negative side of a main carrier frequency.
  • the N / 2 subcarriers on the negative side are switched off, i.e. without signal energy.
  • the N / 2 subcarriers on the positive (p) side are transmitted with an amplitude that is equal to one another to form the frame synchronization signal.
  • FIG. 4 shows a basic structure of a receiving device for an OFDM received signal.
  • Received signal is amplified in an amplifier 10 and pre-filtered with a bandpass filter 11.
  • a mixer stage 12 to which a first reference frequency f ref 1 is supplied, the received signal is mixed down to an intermediate frequency, then filtered again with a bandpass filter 13 and then divided into a branch stage 14.
  • An output branch of branch stage 14 is connected to the input of a further mixer stage 15, to which a second reference signal f ref2 is fed.
  • the signal mixed into the baseband in this way reaches an OFDM demodulator 17 on the one hand via an analog-digital converter 16 and on the other hand 9 to a synchronization unit 18.
  • the synchronization unit 18 is responsible for the block, clock and frequency synchronization.
  • the functional sequences of the OFDM demodulator 17 and the synchronization unit 18 are controlled by a control unit 19.
  • the other output of the branching stage 14 reaches a detection device 20 for recognizing the frame synchronization signal.
  • the detection device 20 generates an output signal with which the control unit 19 is informed of the fact and the time of the occurrence of a frame symbol.
  • the control unit 19 then issues a command to the synchronization unit 18 to carry out the exact synchronization. When this is done, pass the
  • Synchronization unit 18 sends the determined data about frequency offset and block start to the OFDM demodulator 17, which then demodulates the signal and provides a received data sequence on the output side.
  • the analog implementation of the detection of the frame detection signal shown here has the advantage that it can be carried out completely independently of the remaining digital signal processing.
  • the start of the frame is not recognized by active observation of the channel (as in the correlation). Rather, an event is triggered when the frame symbol occurs, i.e. the receiving device is passive and is notified by the frame synchronization signal.
  • the method according to the invention can also be used to wake up the receiving device from a power saving mode, as a result of which energy-efficient mobile subscriber terminals can be implemented.
  • FIG. 5 illustrates the structure of a detection device 20, the branched intermediate frequency signal 10 is fed to the output of branch stage 14.
  • This input signal is divided into two branches, each of which has a bandpass 21, 22, a downstream squarer 23, 24 and a downstream low pass 25, 26.
  • the bandpass filter 21 filters out the upper frequency band (p) and the bandpass filter 22 filters out the lower frequency band (n). Both filtered signal components are mixed linearly into the baseband by the squarers 23, 24 and filtered by a low-pass filter 25, 26.
  • the detection device 20 'shown in FIG. 6 has the identical components 21 to 26 for generating the signals s p (t) and s n (t) and an identical comparison device 27 for the frame synchronization signal according to FIG. 3.
  • an addition stage 28 is also provided, in which the two signals s p (t) and s n (t) are added and are detected in an evaluation device 29 for recognizing a zero signal. If the sum at the output of the addition stage 28 is less than a threshold value slightly above the noise intensity, a conclusion can be drawn about a zero signal.
  • the comparison stage 27 outputs a positive output signal
  • the evaluation device 29 outputs a positive output signal.
  • an AND stage 30 can emit a frame detection signal d (t) to the control device 19. 11
  • the probability of incorrect detections is significantly reduced.
  • the prerequisite is, of course, that the corresponding transmitter transmits a zero signal at the start of the signal frame 1 immediately before or after the frame detection signal according to FIG. 3.
  • the comparison device 27 compares the signals s P (t) and s n (t) and generates a corresponding output signal d (t).
  • the inverted signal s n (t) is fed to an addition stage 30 and the difference formed in this way is compared in a threshold value detector 31 with a set threshold value.
  • This arrangement has the least complexity, but has the disadvantage that the optimal threshold depends on the attenuation of the transmission signal.
  • the hardware is implemented in that the input signals s p (t) and s n (t) are each fed to a logarithmizer 32, 33 and then the difference between the logarithmic signals is formed in the addition stage 30. Mathematically, this corresponds to the formation of the logarithm of the quotient of the signals s p (t) and s n (t).
  • FIG. 9 shows a comparison stage 27 that matches the condition
  • the logarithmers 32, 33 are each preceded by an addition stage 34, 35, the addition stage 34 receiving the input signal s p (t) and the inverted input signal s n (t) and the addition stage 35 the input signals s p (t) us s n (t) are supplied without inversion.
  • This realization of the comparison device 27 allows the variance of the detection time to be reduced compared to the method according to FIG. 8.
  • FIG. 10 shows a variant of FIG. 3 for the formation of the frame synchronization signal according to the invention.
  • the amplitudes of the subcarriers of the negative side (s) are zero.
  • On the positive (p) side however, only every second subcarrier is occupied with transmission energy, while the subcarriers in between likewise have an amplitude of zero.
  • This periodicity can be evaluated by a correlation and used for fine synchronization in the synchronization unit 18.
  • the frame synchronization signal according to FIG. 10 is also useful for performing a digital frame detection.
  • the received signal is sampled and processed by a Fourier transform (FFT), with an FFT window of half the symbol length
  • a frame synchronization signal is detected precisely at block k, in which the variable H
  • the frame synchronization method according to the invention is particularly suitable for OFDM transmission, which is also shown in the example, since the generation of the signal is much easier in OFDM than in single-carrier methods. In principle, however, it is also possible to use the method according to the invention with single-carrier transmission methods. In this case it is a good idea 14 to store samples of the time signal and read them out if necessary.
  • the intermediate frequency used in the receiving device should be as small as possible. This ensures that low-complexity band passes can be realized.
  • the frame synchronization signal Even if the frame synchronization signal only contains power components in a subband, it can still be used as a reference signal for setting an amplitude gain in the receiver.
  • the frame synchronization signal should be selected so that the envelope has a course that is as constant as possible in the time domain. On the one hand, this is important in order to use the frame synchronization signal for setting the gain control, on the other hand, this prevents the transmitter amplifier from being overdriven.
  • the assignment of the individual subcarriers for the frame synchronization signal is independent of the type of modulation, since the frame synchronization signal is not demodulated. Any points in the signal space (complex plane) can therefore be selected.
  • a combination of frame synchronization signal 1 - frame synchronization signal 2 - can be used as a variation on the arrangement in FIG. 6 instead of detecting a zero signal and a frame synchronization signal, in order to reduce the probability of incorrect detection.
  • all positive subcarrier frequencies can be occupied for the first frame detection signal and all negative subcarrier frequencies for the second frame detection signal.
  • TDD time division duplex
  • FDD frequency division duplex

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Time-Division Multiplex Systems (AREA)

Abstract

L'invention concerne un procédé pour la transmission numérique de données dans un réseau de communication sans fil. Dans le procédé selon l'invention, une communication directrice a lieu d'une station maître à tous les abonnés (liaison descendante) à l'intérieur d'une largeur de bande déterminée d'un canal, à l'aide d'une trame de signalisation déterminée (1). Le début de la trame de signalisation (1) est caractérisé par un signal de synchronisation de trame spécial (5), détectable par les abonnés. On utilise, comme signal de synchronisation de trame, une occupation par des signaux d'émission d'au moins un sous-domaine de la largeur de bande et une non-occupation par des signaux d'émission d'au moins un sous-domaine complémentaire de la largeur de bande.
EP99922038A 1998-04-01 1999-03-18 Synchronisation de trame dans des systemes de transmission a porteuses multiples Withdrawn EP1066707A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19814530A DE19814530A1 (de) 1998-04-01 1998-04-01 Verfahren zur digitalen Übertragung von Daten in einem drahtlosen Kommunikationsnetz und Empfangsgerät zum Empfang von nach dem Verfahren übertragenen Daten
DE19814530 1998-04-01
PCT/DE1999/000758 WO1999052252A1 (fr) 1998-04-01 1999-03-18 Synchronisation de trame dans des systemes de transmission a porteuses multiples

Publications (1)

Publication Number Publication Date
EP1066707A1 true EP1066707A1 (fr) 2001-01-10

Family

ID=7863195

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99922038A Withdrawn EP1066707A1 (fr) 1998-04-01 1999-03-18 Synchronisation de trame dans des systemes de transmission a porteuses multiples

Country Status (5)

Country Link
US (1) US6879649B1 (fr)
EP (1) EP1066707A1 (fr)
JP (1) JP4298918B2 (fr)
DE (1) DE19814530A1 (fr)
WO (1) WO1999052252A1 (fr)

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US6985433B1 (en) * 2000-09-15 2006-01-10 Flarion Technologies, Inc. Methods and apparatus for determining minimum cyclicprefix durations
DE10136698A1 (de) 2001-07-27 2003-02-13 Infineon Technologies Ag Vorrichtung zum Entzerren eines Empfangssignals
ATE445263T1 (de) * 2005-11-11 2009-10-15 Ericsson Telefon Ab L M Filter und verfahren zur unterdrückung von effekten von nachbarkanalstörungen
CN102106106B (zh) * 2008-07-10 2014-06-04 新加坡科技研究局 用于判断在所接收的信号中是否存在传输信号的方法、装置和计算机可读介质
US8509343B2 (en) * 2009-06-03 2013-08-13 Qualcomm Incorporated Methods and apparatus for amplifying and transmitting signals
EP3481020B1 (fr) 2017-11-07 2021-09-01 Siemens Aktiengesellschaft Procédé de synchronisation d'unités d'émission et de réception dans une transmission de signaux multiporteuse

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Also Published As

Publication number Publication date
DE19814530A1 (de) 1999-10-07
JP4298918B2 (ja) 2009-07-22
US6879649B1 (en) 2005-04-12
JP2002510939A (ja) 2002-04-09
WO1999052252A1 (fr) 1999-10-14

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