EP0589895A1 - Process and arrangement for the differential modulation of signals in a multi-channel transmission system - Google Patents

Process and arrangement for the differential modulation of signals in a multi-channel transmission system

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Publication number
EP0589895A1
EP0589895A1 EP92908599A EP92908599A EP0589895A1 EP 0589895 A1 EP0589895 A1 EP 0589895A1 EP 92908599 A EP92908599 A EP 92908599A EP 92908599 A EP92908599 A EP 92908599A EP 0589895 A1 EP0589895 A1 EP 0589895A1
Authority
EP
European Patent Office
Prior art keywords
data
subcarrier
subcarriers
modulation
modulation method
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.)
Ceased
Application number
EP92908599A
Other languages
German (de)
French (fr)
Inventor
Andreas MÜLLER
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.)
Daimler Benz AG
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Daimler Benz AG
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Filing date
Publication date
Application filed by Daimler Benz AG filed Critical Daimler Benz AG
Publication of EP0589895A1 publication Critical patent/EP0589895A1/en
Ceased legal-status Critical Current

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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

Definitions

  • the invention relates to a digital modulation method and an arrangement for a multichannel transmission system, in which the data stream is divided into a number of subcarriers which lie next to one another in the frequency range.
  • the invention finds i.a. Use in the COFDM (Coded Orthogonal Freguency Division Multiplexing) method used in digital broadcasting.
  • COFDM Coded Orthogonal Freguency Division Multiplexing
  • the data stream to be transmitted is divided into a number (for example several 100) subcarriers, which lie next to one another in the frequency range, the spectra of the subcarriers also being able to overlap.
  • This procedure means that an order of magnitude lower than the original data rate is transmitted in each subcarrier, which increases the symbol duration accordingly. This has an advantageous effect if echoes occur on the transmission channel.
  • a multi-channel modulation method can always be designed in such a way that the symbol duration is large compared to the maximum echo delay to be expected.
  • the echo influence can e.g. switch off completely in that the symbols are not sent in direct succession, but rather that a protection time is provided between two successive symbols in which the echoes of the symbol sent first decay.
  • a multi-channel modulation method is e.g. as a digital method, for example as a program on at least one microprocessor with which the transmission signal in the complex baseband is calculated on the transmitter side or on an intermediate frequency. With known analog technology methods, this can then be placed in the carrier frequency position. Accordingly, the signal is first received in an analog manner in the receiver, then reduced to baseband or to an intermediate frequency and then further processed digitally.
  • the multi-channel modulation signal consists of time-frequency slots.
  • the time slots are determined by the discrete symbol clock, the frequency slots by the subcarrier Frequency spacing formed. If measures for combating echoes, for example the protection time mentioned above, are provided, the influence of the radio channel in each time-frequency slot consists in an attenuation and phase shift. Attenuation and phase shift are generally variable in time and frequency.
  • the known phase modulation is preferably used as the modulation method for a subcarrier of the multichannel signal.
  • the different data symbols are mapped onto different phase profiles of the transmission signal.
  • the channel-related phase shift then has an effect as a disturbance variable, which must be compensated for by suitable measures.
  • differential demodulation and differential precoding are differential demodulation and differential precoding.
  • the data are not transmitted in the phase of a symbol but in the phase difference of two successive symbols.
  • the differential demodulation and precoding are carried out separately in each subcarrier.
  • the differential precoding takes place in the transmitter (FIG. 1 a) and the differential demodulation takes place in the receiver (FIG. 1 b).
  • the multiplication of complex numbers corresponds to an addition of their phases, the formation of the conjugate complex number of the inversion of the sign of the phase.
  • the differential demodulation or precoding is based on the assumption that the channel-related phase rotation does not change from one symbol to the next. However, this assumption is often not met in the case of time-varying radio channels, particularly in the case of multi-channel methods with their relatively long symbol duration. Then transmission errors occur even in the noise-free state.
  • the invention is therefore based on the object
  • parts of a transmission-side and a reception-side arrangement are shown with a plurality of subcarriers ... k-1, k, k + 1 ..., each of which contains a multiplier on the transmitter side and the receiver side , which links the data of neighboring subcarriers.
  • the multiplied data of the subcarriers k-1, k are fed to the multiplier of the subcarrier k + 1 and multiplied by the data of the subcarrier k + 1.
  • this signal of subcarrier k + 1 is multiplied by the conjugate complex signal of subcarrier k.
  • This method is referred to as frequency differential modulation.
  • the method implemented with this arrangement is based on the assumption that the channel-related phase rotation does not change from one subcarrier to the next. This assumption is similar to that in the known differential modulation, only that the frequency invariance is substituted for the time invariance. Especially in the case of multichannel modulation methods, however, the latter is often more likely because the long symbol duration corresponds to a small frequency spacing of the subcarriers.
  • an arrangement on the transmitting and receiving side is specified, in which both data symbols of a subcarrier, which are consecutive in time, and data of neighboring subcarriers are linked to one another.
  • data which are transmitted in phase difference between two successive data symbols are given to a multiplier by the multiplied data of the subcarriers k-1, k.
  • This multiplied, complex signal of the subcarrier k + 1 is multiplied in the receiver by the conjugate complex signal of the subcarrier k. Then this multiplied signal with the conjugate complex, time-delayed signal is given to another multiplier.
  • the signals of the subcarriers are precoded differentially first and then frequency differential in the transmitter and then in the Receiver first demodulated differentially and then frequency differentially.
  • the double differential modulation can also be carried out first on the transmitter and receiver side by means of a frequency differential and a subsequent differential modulation.
  • double differential modulation has the decisive advantage that it does not require the assumption of a temporal invariance or a frequency invariance of the channel-related phase rotation, but rather the channel phase curve over time and frequency by a Approximate level. In radio channels, this approximation is significantly better than the approximation due to a phase curve that is constant over time and frequency.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Radio Transmission System (AREA)
  • Transmitters (AREA)

Abstract

La présente invention se rapporte à un procédé de molulation numérique et à un agencement pour un système de transmission à canaux multiples dans lequel le flux de données est répartie sur plusieurs sous-porteuses juxtaposées dans la gamme de fréquences. Des sous-porteuses voisines sont reliées entre elles de telle manière que les données de deux sous-porteuses voisines sont transmises en différence de phase. Si l'on relie une telle modulation différentielle en fréquence à une modulation différentielle usuelle, dans laquelle des symboles de données successifs d'une sous-porteuse sont transmis en différence de phase, on obtient une qualité de transmission nettement meilleure des signaux dans les canaux radio.The present invention relates to a digital modulation method and an arrangement for a multi-channel transmission system in which the data stream is distributed over several juxtaposed sub-carriers in the frequency range. Neighboring sub-carriers are interconnected in such a way that the data of two neighboring sub-carriers are transmitted in phase difference. If such a differential frequency modulation is connected to a usual differential modulation, in which successive data symbols of a subcarrier are transmitted in phase difference, a significantly better quality of transmission of the signals in the channels is obtained. radio.

Description

Beschreibungdescription
Verfahren und Anordnung zur differentiellen Modulation von Signalen in einem Mehrkanal-ÜbertraqunqssystemMethod and arrangement for differential modulation of signals in a multi-channel transmission system
Die Erfindung betrifft ein digitales Modulationsverfahren und eine Anordnung für ein Mehrkanal-Übertragungssyεtem, bei dem der Datenstrom auf mehrere Unterträger aufgeteilt wird, die im Frequenzbereich nebeneinander -liegen.The invention relates to a digital modulation method and an arrangement for a multichannel transmission system, in which the data stream is divided into a number of subcarriers which lie next to one another in the frequency range.
Die Erfindung findet u.a. Verwendung bei dem im digitalen Rundfunk eingesetzten COFDM (Coded Orthogonal Freguency Division Multiplexing) Verfahren.The invention finds i.a. Use in the COFDM (Coded Orthogonal Freguency Division Multiplexing) method used in digital broadcasting.
Bei einem Mehrkanal-Modulationsverfahren zur digitalen Da¬ tenübertragung wird der zu übertragende Datenstrom auf eine Anzahl (z.B. mehrere 100) Unterträger aufgeteilt, die im Frequenzbereich nebeneinander liegen, wobei die Spektren der Unterträger sich auch überlappen können. Durch diese Vorgehensweise wird in jedem Unterträger eine um Größenordnungen niedrigere als die ursprüngliche Daten- rate übertragen, wodurch die Symboldauer sich entsprechend vergrößert. Dies wirkt sich dann vorteilhaft aus, wenn auf dem Übertragungskanal Echos entstehen. Durch geeignete Festlegung der Anzahl der Unterträger läßt sich ein Mehr¬ kanal-Modulationsverfahren stets so auslegen, daß die Sym- boldauer groß gegen die maximal zu erwartende Echolaufzeit ist.In a multi-channel modulation method for digital data transmission, the data stream to be transmitted is divided into a number (for example several 100) subcarriers, which lie next to one another in the frequency range, the spectra of the subcarriers also being able to overlap. This procedure means that an order of magnitude lower than the original data rate is transmitted in each subcarrier, which increases the symbol duration accordingly. This has an advantageous effect if echoes occur on the transmission channel. By appropriately determining the number of subcarriers, a multi-channel modulation method can always be designed in such a way that the symbol duration is large compared to the maximum echo delay to be expected.
Der Echoeinfluß läßt sich z.B. dadurch ganz ausschalten, daß die Symbole nicht unmittelbar aufeinander folgend ge- sendet werden, sondern daß zwischen zwei aufeinanderfol¬ genden Symbolen jeweils eine Schutzzeit vorgesehen ist, in der die Echos des zuerst gesendeten Symbols abklingen.The echo influence can e.g. switch off completely in that the symbols are not sent in direct succession, but rather that a protection time is provided between two successive symbols in which the echoes of the symbol sent first decay.
Die technische Ausgestaltung eines Mehrkanal-Modulations- Verfahrens erfolgt z.B. als digitales Verfahren, etwa als Programm auf mindestens einem Mikroprozessor mit dem sen- derseitig das Sendesignal im komplexen Basisband oder auf einer Zwischenfrequenz berechnet wird. Mit bekannten Ana¬ logtechnik-Methoden kann dieses dann in die Trägerfre- quenzlage gesetzt werden. Entsprechend wird im Empfänger das Signal zunächst auf analoge Weise empfangen, dann ins Basisband oder auf eine Zwischenfrequenz heruntergesetzt und dann digital weiterverarbeitet.The technical design of a multi-channel modulation method is e.g. as a digital method, for example as a program on at least one microprocessor with which the transmission signal in the complex baseband is calculated on the transmitter side or on an intermediate frequency. With known analog technology methods, this can then be placed in the carrier frequency position. Accordingly, the signal is first received in an analog manner in the receiver, then reduced to baseband or to an intermediate frequency and then further processed digitally.
Das Mehrkanal-Modulationssignal besteht aus Zeit-Frequenz- Schlitzen. Die Zeitschlitze werden durch den diskreten Symboltakt, die Frequenzschlitze durch den Unterträger- Frequenzabstand gebildet. Wenn Maßnahmen zur Bekämpfung von Echos, z.B. die oben erwähnte Schutzzeit, vorgesehen sind, besteht der Einfluß des Funkkanals in jedem Zeit- Frequenz-Schlitz in einer Dämpfung und Phasendrehung. Dämpfung und Phasendrehung sind in der Regel zeit- und frequenzveränderlich.The multi-channel modulation signal consists of time-frequency slots. The time slots are determined by the discrete symbol clock, the frequency slots by the subcarrier Frequency spacing formed. If measures for combating echoes, for example the protection time mentioned above, are provided, the influence of the radio channel in each time-frequency slot consists in an attenuation and phase shift. Attenuation and phase shift are generally variable in time and frequency.
Als Modulationsverfahren für einen Unterträger des Mehrka¬ nal-Signals wird bevorzugt die bekannte Phasenmodulation verwendet. Dabei werden die verschiedenen Datensymbole auf unterschiedliche Phasenverläufe des Sendeεignals abgebil¬ det. Für die Demodulation wirkt sich dann die kanalbe¬ dingte Phasendrehung als Störgröße aus, die durch ge¬ eignete Maßnahmen zu kompensieren ist.The known phase modulation is preferably used as the modulation method for a subcarrier of the multichannel signal. The different data symbols are mapped onto different phase profiles of the transmission signal. For the demodulation, the channel-related phase shift then has an effect as a disturbance variable, which must be compensated for by suitable measures.
Bekannte Methoden sind die differentielle Demodulation und die differentielle Vorcodierung. Hierbei werden die Daten nicht in der Phase eines Symbols sondern in der Phasendif¬ ferenz zweier aufeinanderfolgender Symbole übertragen. Bei einem Mehrkanal-Verfahren wird die differentielle Demodu¬ lation und Vorcodierung in jedem Unterträger separat durchgeführt.Known methods are differential demodulation and differential precoding. In this case, the data are not transmitted in the phase of a symbol but in the phase difference of two successive symbols. In the case of a multi-channel method, the differential demodulation and precoding are carried out separately in each subcarrier.
Die differentielle Vorcodierung erfolgt im Sender (Fig. la) und die differentielle Demodulation erfolgt im Empfän¬ ger (Fig.lb) .The differential precoding takes place in the transmitter (FIG. 1 a) and the differential demodulation takes place in the receiver (FIG. 1 b).
Die Multiplikation komplexer Zahlen entspricht einer Addi¬ tion ihrer Phasen, die Bildung der konjugiert komplexen Zahl der Inversion des Vorzeichens der Phase. **D" kenn¬ zeichnet in Fig. la, lb die Verzögerung um ein Symbol, * bezeichnet den konjugiert komplexen Anteil. Der differentiellen Demodulation bzw. Vorcodierung liegt die Annahme zugrunde, daß sich die kanalbedingte Phasen¬ drehung von einem Symbol zum nachfolgenden nicht ändert. Bei zeitveränderlichen Funkkanälen ist diese Annahme häu¬ fig jedoch nicht erfüllt, besonders bei Mehrkanal-Verfah¬ ren mit ihrer relativ langen Symboldauer. Dann treten selbst im rauschfreien Zustand Übertragungεfehler auf.The multiplication of complex numbers corresponds to an addition of their phases, the formation of the conjugate complex number of the inversion of the sign of the phase. ** D "in FIG. 1 a, 1 b denotes the delay by one symbol, * denotes the conjugate complex part. The differential demodulation or precoding is based on the assumption that the channel-related phase rotation does not change from one symbol to the next. However, this assumption is often not met in the case of time-varying radio channels, particularly in the case of multi-channel methods with their relatively long symbol duration. Then transmission errors occur even in the noise-free state.
Der Erfindung liegt deshalb die Aufgabe zugrunde, einThe invention is therefore based on the object
Modulationsverfahren und eine Anordnung für ein Mehrkanal- ÜbertragungsSystem anzugeben, bei dem die Übertragungsqua- lität der Signale von instationären Funkkanälen verbessert wird.Specify modulation method and an arrangement for a multi-channel transmission system, in which the transmission quality of the signals of unsteady radio channels is improved.
Die Aufgabe wird durch die kennzeichnenden Merkmale der Patentansprüche 1 bis 4 gelöst. Eine weitere Ausgestaltung ist in Anspruch 5 enthalten.The object is achieved by the characterizing features of claims 1 to 4. A further embodiment is contained in claim 5.
Die Erfindung wird im folgenden anhand von Ausführungsbei- spielen beschrieben unter Bezugnahme auf schematische Zeichnungen.The invention is described below with reference to exemplary embodiments with reference to schematic drawings.
In einem Ausführungsbeispiel gemäß Fig. 2 sind Teile einer sendeseitigen und einer empfangsseitigen Anordnung darge¬ stellt mit mehreren Unterträgern ...k-1, k, k+1..., die auf der Senderseite und der Empfängerseite je einen Multi¬ plikator enthalten, der jeweils die Daten benachbarter Un¬ terträger verknüpft. Im Sender werden beispielsweise die multiplizierten Daten der Unterträger k-1, k dem Multipli¬ kator des Unterträgers k+1 zugeführt und mit den Daten des Unterträgers k+1 multipliziert. Auf der Empfängerseite wird dieses Signal, des Untertragers k+1 mit dem konju¬ giert komplexen Signal des Unterträgers k multipliziert. Dieses Verfahren wird als frequenzdifferentielle Modula¬ tion bezeichnet.In an exemplary embodiment according to FIG. 2, parts of a transmission-side and a reception-side arrangement are shown with a plurality of subcarriers ... k-1, k, k + 1 ..., each of which contains a multiplier on the transmitter side and the receiver side , which links the data of neighboring subcarriers. In the transmitter, for example, the multiplied data of the subcarriers k-1, k are fed to the multiplier of the subcarrier k + 1 and multiplied by the data of the subcarrier k + 1. On the receiving end this signal of subcarrier k + 1 is multiplied by the conjugate complex signal of subcarrier k. This method is referred to as frequency differential modulation.
Dem mit dieser Anordnung realisierten Verfahren liegt die Annahme zugrunde, daß sich die kanalbedingte Phasendrehung von einem Unterträger zum nächsten nicht ändert. Diese An¬ nahme ist ähnlich derjenigen bei der bekannten differenti- eilen Modulation, nur daß an Stelle der Zeitinvarianz die Frequenzinvarianz getreten ist. Gerade bei Mehrkanal-Mo¬ dulationsverfahren ist letztere jedoch häufig eher gege¬ ben, da der langen Symboldauer ein kleiner Frequenzabstand der Unterträger entspricht.The method implemented with this arrangement is based on the assumption that the channel-related phase rotation does not change from one subcarrier to the next. This assumption is similar to that in the known differential modulation, only that the frequency invariance is substituted for the time invariance. Especially in the case of multichannel modulation methods, however, the latter is often more likely because the long symbol duration corresponds to a small frequency spacing of the subcarriers.
In einem weiteren Ausführungsbeispiel gemäß Fig. 3 wird eine sende- und e pfangsseitige Anordnung angegeben, bei der sowohl zeitlich aufeinanderfolgende Datensymbole eines Unterträgers als auch Daten benachbarter Unterträger mit- einander verknüpft werden. Beispielsweise werden im Unter¬ träger k+1 des Senders Daten, die in Phasendifferenz zweier aufeinanderfolgender Datensymbole übertragen wer¬ den, mit den multiplizierten Daten der Unterträger k-1, k auf einen Multiplikator gegeben. Im Empfänger wird dieses multiplizierte, komplexe Signal des Unterträgers k+1 mit dem konjugiert komplexen Signal des Unterträgers k multi¬ pliziert. Anschließend wird dieses multiplizierte Signal mit dem konjugiert komplexen, zeitlich verzögerten Signal auf einen weiteren Multiplikator gegeben. Mi dieser dop- pelten differentiellen Modulation werden im Sender die Si¬ gnale der Unterträger zuerst differentiell und an¬ schließend frequenzdifferentiell vorcodiert und dann im Empfänger zuerst differentiell und anschließend frequenz- differentiell demoduliert. Die doppelte differentielle Mo¬ dulation kann auch sende- wie empfängerseitig zuerst durch eine frequenzdifferentielle und eine anschließende diffe- rentielle Modulation durchgeführt werden.In a further exemplary embodiment according to FIG. 3, an arrangement on the transmitting and receiving side is specified, in which both data symbols of a subcarrier, which are consecutive in time, and data of neighboring subcarriers are linked to one another. For example, in the subcarrier k + 1 of the transmitter, data which are transmitted in phase difference between two successive data symbols are given to a multiplier by the multiplied data of the subcarriers k-1, k. This multiplied, complex signal of the subcarrier k + 1 is multiplied in the receiver by the conjugate complex signal of the subcarrier k. Then this multiplied signal with the conjugate complex, time-delayed signal is given to another multiplier. With this double differential modulation, the signals of the subcarriers are precoded differentially first and then frequency differential in the transmitter and then in the Receiver first demodulated differentially and then frequency differentially. The double differential modulation can also be carried out first on the transmitter and receiver side by means of a frequency differential and a subsequent differential modulation.
Die doppelt differentielle Modulation bietet gegenüber der konventionellen differentiellen Modulation und auch gegen¬ über der frequenzdifferentiellen Modulation den entschei- denden Vorteil, daß sie weder die Annahme einer zeitlichen Invarianz noch einer Frequenzinvarianz der kanalbedingten Phasendrehung benötigt, sondern den Kanalphasenverlauf über der Zeit und Frequenz durch eine Ebene approximiert. Diese Approximation ist bei Funkkanälen deutlich besser als die Approximation durch einen über der Zeit bzw. der Frequenz konstanten Phasenverlauf. Compared to conventional differential modulation and also compared to frequency differential modulation, double differential modulation has the decisive advantage that it does not require the assumption of a temporal invariance or a frequency invariance of the channel-related phase rotation, but rather the channel phase curve over time and frequency by a Approximate level. In radio channels, this approximation is significantly better than the approximation due to a phase curve that is constant over time and frequency.

Claims

Patentansprüche Claims
1. Mehrkanal-Modulationsverfahren, bei dem der Datenstrom auf mehrere Unterträger aufgeteilt wird, die im Frequenz¬ bereich nebeneinander liegen, dadurch gekennzeichnet, daß die Daten in Phasendifferenz benachbarter Unterträger übertragen werden.1. Multi-channel modulation method in which the data stream is divided into a number of subcarriers which lie next to one another in the frequency range, characterized in that the data are transmitted in phase difference between adjacent subcarriers.
2. Mehrkanal-Modulationsverfahren nach dem Oberbegriff des Anspruchs 1, dadurch gekennzeichnet, daß die Daten in Pha¬ sendifferenz benachbarter Unterträger und in Phasendiffe- renz zeitlich aufeinanderfolgender Datensymbole in dem je¬ weiligen Unterträger übertragen werden.2. Multi-channel modulation method according to the preamble of claim 1, characterized in that the data are transmitted in phase difference of adjacent subcarriers and in phase difference of temporally successive data symbols in the respective subcarrier.
3. Empfänger- und Senderanordnung für ein Mehrkanal-Modu¬ lationsverfahren nach den Ansprüchen 1 und 2, dadurch gekennzeichnet, daß empfangs- und sendeseitig in jedem Unterträger mindestens ein Multiplikator enthalten ist, der die Daten benachbarter Unterträger verknüpft.3. Receiver and transmitter arrangement for a multi-channel modulation method according to claims 1 and 2, characterized in that at the receiving and transmitting end, each subcarrier contains at least one multiplier which links the data of neighboring subcarriers.
4. Empfänger- und Senderanordnung für ein Mehrkanal-Modu¬ lationsverfahren nach Anspruch 2, dadurch gekennzeichnet, - daß empfangs- und sendeseitig in jedem Unterträger ein Multiplikator enthalten ist, der die Daten zweier zeitlich aufeinanderfolgender Datensymbole im jeweiligen Unterträger verknüpft und daran an¬ schließend ein weiterer Multiplikator angeordnet ist, der die Daten benachbarter Unterträger ver¬ knüpft.4. Receiver and transmitter arrangement for a multi-channel modulation method according to claim 2, characterized in that - on the receiving and transmitting side, a multiplier is included in each subcarrier, which links the data of two temporally successive data symbols in the respective subcarrier and then follows them a further multiplier is arranged which links the data of neighboring subcarriers.
5. Empfänger- und Sender nordnung für ein Mehrkanal-Modu¬ lationsverfahren nach Anspruch 2, dadurch gekennzeichnet, daß empfangs- und sendeseitig in jedem Unterträger ein Multiplikator enthalten ist, der die Daten benachbarter Unterträger verknüpft und daran anschließend ein weiterer Multiplikator angeordnet ist, der die Daten zweier zeit¬ lich aufeinanderfolgender Datensymbole im jeweiligen Un¬ terträger verknüpft. 5. Receiver and transmitter arrangement for a multi-channel modulation method according to claim 2, characterized in that on the receiving and transmitting side a multiplier is included in each subcarrier, which links the data of adjacent subcarriers and then a further multiplier is arranged, which the data of two chronologically successive data symbols are linked in the respective subcarrier.
EP92908599A 1991-05-02 1992-04-14 Process and arrangement for the differential modulation of signals in a multi-channel transmission system Ceased EP0589895A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4114274 1991-05-02
DE4114274A DE4114274A1 (en) 1991-05-02 1991-05-02 METHOD AND ARRANGEMENT FOR DIFFERENTIAL MODULATION OF SIGNALS IN A MULTI-CHANNEL TRANSMISSION SYSTEM
PCT/EP1992/000841 WO1992020179A1 (en) 1991-05-02 1992-04-14 Process and arrangement for the differential modulation of signals in a multi-channel transmission system

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JP (1) JPH06507053A (en)
AU (1) AU652052B2 (en)
CA (1) CA2109211A1 (en)
DE (1) DE4114274A1 (en)
FI (1) FI934830A (en)
WO (1) WO1992020179A1 (en)

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WO1992020179A1 (en) 1992-11-12
FI934830A0 (en) 1993-11-01
DE4114274A1 (en) 1992-11-05
AU1643092A (en) 1992-12-21
CA2109211A1 (en) 1992-11-03
FI934830A (en) 1993-11-01
AU652052B2 (en) 1994-08-11

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