EP1391093A1 - Recognition of modulation type by means of a marked phase rotation factor of a training sequence - Google Patents

Recognition of modulation type by means of a marked phase rotation factor of a training sequence

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Publication number
EP1391093A1
EP1391093A1 EP02771624A EP02771624A EP1391093A1 EP 1391093 A1 EP1391093 A1 EP 1391093A1 EP 02771624 A EP02771624 A EP 02771624A EP 02771624 A EP02771624 A EP 02771624A EP 1391093 A1 EP1391093 A1 EP 1391093A1
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EP
European Patent Office
Prior art keywords
training sequence
phase rotation
modulation
output sequence
data
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
EP02771624A
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German (de)
French (fr)
Inventor
Bin Yang
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Infineon Technologies AG
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Infineon Technologies AG
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Publication of EP1391093A1 publication Critical patent/EP1391093A1/en
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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
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H04L27/20—Modulator circuits; Transmitter circuits
    • H04L27/2003—Modulator circuits; Transmitter circuits for continuous phase modulation
    • H04L27/2007—Modulator circuits; Transmitter circuits for continuous phase modulation in which the phase change within each symbol period is constrained
    • H04L27/2017—Modulator circuits; Transmitter circuits for continuous phase modulation in which the phase change within each symbol period is constrained in which the phase changes are non-linear, e.g. generalized and Gaussian minimum shift keying, tamed frequency modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0008—Modulated-carrier systems arrangements for allowing a transmitter or receiver to use more than one type of modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0012—Modulated-carrier systems arrangements for identifying the type of modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H04L27/20—Modulator circuits; Transmitter circuits
    • H04L27/2032—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner
    • H04L27/2053—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases
    • H04L27/206—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases using a pair of orthogonal carriers, e.g. quadrature carriers
    • H04L27/2067—Modulator circuits; Transmitter circuits for discrete phase modulation, e.g. in which the phase of the carrier is modulated in a nominally instantaneous manner using more than one carrier, e.g. carriers with different phases using a pair of orthogonal carriers, e.g. quadrature carriers with more than two phase states

Definitions

  • the present invention relates generally to digital communication systems, particularly to mobile radio systems.
  • the invention relates in particular to a transmission and reception method and a receiver in a digital telecommunications system according to the preamble of the independent claims.
  • the EDGE (Enhanced Data Rates for GSM Evolution) standard and the associated EGPRS (Enhanced GPRS) package service were defined as the transition standard between the GSM / GPRS and UMTS mobile communications standards. Both the GMSK and the 8-PSK modulation are used in the EDGE standard. GMSK modulation uses a signal space with signal points +1 and -1, while 8-PSK modulation uses a signal space with eight signal points. If the type of modulation to be used in the transmission of information between a transmitter and a receiver is not fixed, the receiver must be informed of the type of modulation used.
  • WO 00/10301 which is hereby incorporated into the disclosure content of the present application, describes a method for transmitting and recognizing the type of modulation in digital communication systems which makes use of the training sequence present in a data burst.
  • Each data burst comprises a predetermined training sequence consisting of a sequence of data symbols known to the receiver, which is used in the receiver for purposes of channel estimation.
  • it is proposed to label every conceivable type of modulation with a certain phase rotation factor and to To apply training phase with the phase rotation factor, ie to rotate the data symbols contained in it with the phase rotation factor.
  • the same phase rotation factor that is also used for the modulation of the user data is preferably used here.
  • the GMSK and the 8-PSK modulation are distinguished by a different symbol rotation. While the GMSK modulation rotates each transmission symbol by 90 degrees, the 8-PSK modulation rotates 67.5 degrees per transmission symbol.
  • the data symbols of the transmitted training sequence which are phase-rotated in this way, can be used in the receiver in such a way that, at the beginning of each data burst, the received training sequence is turned back in a number of data paths by a corresponding number of phase rotation factors.
  • the received training sequence is turned back by 90 and 67.5 degrees, respectively.
  • the received and reversed training sequence is then compared with a training sequence that has been subjected to a channel filter function obtained from a channel estimate. The comparison is made by subtracting these training sequences from each other, adding up the squared differences and detecting the minimum.
  • This method has the disadvantage that a channel estimation must be carried out in each of the data paths provided for the derotation with the different phase rotation factors and only after the channel estimation has been carried out and the original training sequence has been loaded with the channel parameters by the aforementioned channel filter function, the comparison with the received and respectively rotated training sequence can be done.
  • This method is very complex and requires a large number of circuit units in the receiver.
  • the invention is based on the essential knowledge that it is not absolutely necessary to carry out a channel estimation in each data path of the receiver in which the received training sequence is reversed or derotated.
  • the invention deliberately dispenses with channel estimation at this early stage of the detection of the type of modulation. Instead, each received and derotated training sequence is compared directly with the original, unfiltered training sequence. The comparison is made by a correlation, i.e. a multiplication of the two training sequences with each other.
  • the type of modulation is determined according to which phase rotation factor in the respective data path achieves a maximum during the back rotation and the subsequent correlation.
  • the invention is not limited to using the training sequence usually present in a data burst in the manner described.
  • any other sequence of information data that is transmitted during the communication anyway can be used in the manner according to the invention in order to transmit information about the type of modulation.
  • the present invention does not require channel estimates for the detection of the type of modulation, since a correlation between the received and derotated training sequence is carried out with the original, unfiltered training sequence.
  • the original training sequence is therefore not subjected to a channel filter function before the correlation step is carried out.
  • the invention Thus, only a number of data paths are provided in the receiver, in which derotations of the received training sequence are carried out by predetermined phase rotation factors, with a correlation being carried out in each data path following the derotation, in which the received and deroted training sequence with the original, unfiltered Training sequence is correlated.
  • a channel estimation is only carried out after the detection of the type of modulation.
  • Another difference to the generic document mentioned above is the type of mathematical comparison of the training sequences. While the training sequences to be compared are subtracted from one another in the cited prior art, a correlation function is formed according to the invention. If the temporal position of the training sequence within the received data burst is only known to a certain accuracy, provision can also be made for the derotation and correlation to be carried out several times in succession in each data path, the training sequences to be multiplied in the correlation step being incrementally shifted with respect to one another and the maximum correlation result is determined from these multiple correlation steps.
  • the invention is explained in more detail below on the basis of an exemplary embodiment.
  • the exemplary embodiment relates to the use of the two modulation types GMSK (Gaussian minimum shift keying) and 8-PSK (8-ary phase shift keying).
  • GMSK Gausian minimum shift keying
  • 8-PSK 8-ary phase shift keying
  • the GMSK modulation can be approximated by an amplitude modulation and therefore interpreted as follows:
  • the GMSK symbols a are rotated with ⁇ / 2 radians per symbol:
  • ⁇ is the modulated baseband signal, which is mixed with the desired carrier frequency and then transmitted to the antenna.
  • the 8-PSK modulation is defined in a similar way. However, it differs from GMSK modulation in the number of bits mapped to a symbol and in the rotation:
  • An 8-PSK data symbol therefore contains three times the information content as a GMSK data symbol. Therefore the 8-PSK-Mo- dulation is used for high data transmission, while GMSK modulation is used for low data transmission.
  • Both types of modulation can be used with the EDGE standard and the type of modulation can be changed from burst to burst.
  • the EDGE receiver initially does not know the type of modulation in which the data transmitted to it by the transmitter are modulated. For each burst, the EDGE receiver only recognizes a block of complex baseband input data x k and has to make a decision about the type of modulation used. This approach is therefore also called blind modulation detection.
  • information about the type of modulation used is impressed on the transmitted signal and the predetermined training sequence known to the receiver, which is contained in each GSM / EDGE burst, is used for this purpose.
  • the data symbols of the training sequence are rotated on the transmitter side with a phase rotation factor which is also used for the modulation of the useful signals, although in principle another phase rotation factor can also be used for this.
  • This exemplary embodiment of the blind modulation detection method according to the invention is shown schematically in the single drawing figure.
  • the figure shows the flow diagram for blind modulation detection in a receiver.
  • Two samples are generated from a received training sequence xk and fed into two data paths according to the two types of modulation.
  • N denotes the length of the training sequence.
  • the received training sequence Xk is first derotated by - ⁇ / 2 per symbol for GMSK and by -3 ⁇ / 8 per symbol for 8-PSK.
  • the received and each derotated training sequence y k with the original training sequence correlates t k. Since the correlation can have a complex value due to the unknown phase of the signal, the quadratic magnitude of the correlation is calculated after the summation over the products at the individual time moments k.
  • the correlation result between GMSK and 8-PSK is compared. If the received and deroted training sequence y k GMSK is more similar to the original training sequence t k than the received and deroted training sequence y k 8PSK , ie C GMSK > C 8PSK ⁇ w j_ rc j detects that the corresponding data burst with the Modulation type GMSK is modulated. Otherwise it is detected that the modulation type is 8-PSK.
  • the demodulator can then begin channel estimation.
  • the correlation in each data path is carried out several times in succession by shifting the training sequences to be correlated with one another in time.
  • a first correlation can therefore first be carried out in each data path on the basis of certain assumptions about the temporal position of the training sequence.
  • the data symbols of the sequences t k and y k to be correlated can then be fed to the correlator again and slightly offset from one another. The maximum is then selected from several correlations carried out in this way.
  • the method according to the invention for automatic detection of the type of modulation used is characterized by a high degree of accuracy with little effort compared to the prior art.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

In order to carry out blind modulation detection, the data symbols of the training sequence are rotated on the transmitter side by a phase rotation factor which is specific for the type of modulation used; the data symbols are back-rotated or de-rotated on the receiver side by varous phase reduction factors and a correlation function is formed between the sequences thus obtained and the original training sequence. The type of modulation used is obtained from the phase rotation factor which provides a maximum correlation function.

Description

Beschreibungdescription
ERKENNUNG DER ODULATIONSART MITTELS EINES DER TRAININGSSEQUENZ AUFGEPRÄGTEN PHASENROTATIONSFAKTORSDETECTION OF THE TYPE OF ODULATION BY MEANS OF A PHASE ROTATION FACTOR IMPRESSED ON THE TRAINING SEQUENCE
Die vorliegende Erfindung bezieht sich im allgemeinen auf digitale Kommunikationssysteme, insbesondere auf Mobilfunksysteme. Dabei bezieht sich die Erfindung im besonderen auf ein Sende- und Empfangsverfahren und einen Empfänger in einem digitalen Telekommunikationssystem nach dem Oberbegriff der unabhängigen Patentansprüche .The present invention relates generally to digital communication systems, particularly to mobile radio systems. The invention relates in particular to a transmission and reception method and a receiver in a digital telecommunications system according to the preamble of the independent claims.
Als ÜbergangsStandard zwischen den Mobilfunkstandards GSM/GPRS und UMTS wurde der Standard EDGE (Enhanced Data Rates for GSM Evolution) sowie der zugehörige Paketdienst EGPRS (Enhanced GPRS) definiert. In dem EDGE-Standard wird sowohl die GMSK- als auch die 8-PSK-Modulation verwendet. Die GMSK- Modulation verwendet einen Signalraum mit den Signalpunkten +1 und -1, während bei der 8-PSK-Modulation ein Signalraum mit acht Signalpunkten verwendet wird. Wenn die bei der Informationsübertragung zwischen einem Sender und einem Empfänger zu verwendende Modulationsart nicht fest vorgegeben ist, so muss der Empfänger über die verwendete Modulationsart in- formiert werden.The EDGE (Enhanced Data Rates for GSM Evolution) standard and the associated EGPRS (Enhanced GPRS) package service were defined as the transition standard between the GSM / GPRS and UMTS mobile communications standards. Both the GMSK and the 8-PSK modulation are used in the EDGE standard. GMSK modulation uses a signal space with signal points +1 and -1, while 8-PSK modulation uses a signal space with eight signal points. If the type of modulation to be used in the transmission of information between a transmitter and a receiver is not fixed, the receiver must be informed of the type of modulation used.
In der WO 00/10301, welche hiermit in den Offenbarungsgehalt der vorliegenden Anmeldung einbezogen wird, wird ein Verfahren zur Übermittlung und Erkennung der Modulationsart in di- gitalen Kommunikationssystemen beschrieben, welches von der in einem Datenburst vorhandenen Trainingssequenz Gebrauch macht. Jeder Datenburst umfasst eine fest vorgegebene Trainingssequenz bestehend aus einer dem Empfänger bekannten Abfolge von Datensymbolen, die im Empfänger für Zwecke der Ka- nalschätzung eingesetzt wird. In der erwähnten Druckschrift wird vorgeschlagen, jede denkbare Modulationsart mit einem bestimmten Phasenrotationsfaktor zu kennzeichnen und die Trainingssequenz mit dem Phasenrotationsfaktor zu beaufschlagen, d.h. die in ihr enthaltenen Datensymbole mit dem Phasenrotationsfaktor zu rotieren. Vorzugsweise wird dabei derselbe Phasenrotationsfaktor verwendet, der auch für die Modulation der Nutzdaten zum Einsatz kommt. Bekanntermaßen zeichnen sich die GMSK- und die 8-PSK-Modulation durch eine unterschiedliche Symbolrotation aus. Während die GMSK-Modulation jedes Sendesymbol um 90 Grad weiterdreht, führt die 8-PSK-Modula- tion eine Drehung von 67,5 Grad pro Sendesymbol aus. Die sol- chermaßen phasenrotierten Datensymbole der übertragenen Trainingssequenz können im Empfänger derart ausgenutzt werden, dass zum Beginn jeden Datenbursts die empfangene Trainingssequenz in einer Anzahl von Datenpfaden um eine entsprechende Anzahl von Phasenrotationsfaktoren zurückgedreht wird. In dem genannten Beispiel der zwei Modulationsarten GMSK- und 8-PSK- Modulation wird also die empfangene TrainingsSequenz um jeweils 90 und 67,5 Grad zurückgedreht. Danach wird die empfangene und zurückgedrehte Trainingssequenz mit einer Trainings- sequenz verglichen, die mit einer aus einer KanalSchätzung gewonnenen Kanalfilterfunktion beaufschlagt wurde. Der Vergleich erfolgt durch Subtraktion dieser Trainingssequenzen voneinander, Aufsummieren der quadrierten Differenzen und De- tektion des Minimums .WO 00/10301, which is hereby incorporated into the disclosure content of the present application, describes a method for transmitting and recognizing the type of modulation in digital communication systems which makes use of the training sequence present in a data burst. Each data burst comprises a predetermined training sequence consisting of a sequence of data symbols known to the receiver, which is used in the receiver for purposes of channel estimation. In the mentioned publication it is proposed to label every conceivable type of modulation with a certain phase rotation factor and to To apply training phase with the phase rotation factor, ie to rotate the data symbols contained in it with the phase rotation factor. The same phase rotation factor that is also used for the modulation of the user data is preferably used here. As is known, the GMSK and the 8-PSK modulation are distinguished by a different symbol rotation. While the GMSK modulation rotates each transmission symbol by 90 degrees, the 8-PSK modulation rotates 67.5 degrees per transmission symbol. The data symbols of the transmitted training sequence, which are phase-rotated in this way, can be used in the receiver in such a way that, at the beginning of each data burst, the received training sequence is turned back in a number of data paths by a corresponding number of phase rotation factors. In the example of the two modulation types GMSK and 8-PSK modulation mentioned, the received training sequence is turned back by 90 and 67.5 degrees, respectively. The received and reversed training sequence is then compared with a training sequence that has been subjected to a channel filter function obtained from a channel estimate. The comparison is made by subtracting these training sequences from each other, adding up the squared differences and detecting the minimum.
Dieses Verfahren hat den Nachteil, dass in jedem der für die Derotation mit den verschiedenen Phasenrotationsfaktoren vorgesehenen Datenpfade eine KanalSchätzung durchgeführt werden muss und erst nach erfolgter KanalSchätzung und Beaufschlagung der ursprünglichen Trainingssequenz mit den Kanalparame- tern durch die genannte Kanalfilterfunktion der Vergleich mit der empfangenen und jeweils zurückrotierten Trainingssequenz erfolgen kann. Dieses Verfahren ist sehr aufwendig und erfordert eine Vielzahl von Schaltungseinheiten in dem Empfänger.This method has the disadvantage that a channel estimation must be carried out in each of the data paths provided for the derotation with the different phase rotation factors and only after the channel estimation has been carried out and the original training sequence has been loaded with the channel parameters by the aforementioned channel filter function, the comparison with the received and respectively rotated training sequence can be done. This method is very complex and requires a large number of circuit units in the receiver.
Es ist daher Aufgabe der vorliegenden Erfindung, den Aufwand für die Detektion der Modulationsart in Empfängern digitaler Kommunikationssysteme zu reduzieren. Diese Aufgabe wird durch die kennzeichnenden Merkmale der unabhängigen Patentansprüche gelöst. Vorteilhafte Ausgestaltungen und Weiterbildungen sind in den Unteransprüchen angege- ben.It is therefore an object of the present invention to reduce the effort for the detection of the type of modulation in receivers of digital communication systems. This object is achieved by the characterizing features of the independent claims. Advantageous refinements and developments are specified in the subclaims.
Die Erfindung geht zunächst von der wesentlichen Erkenntnis aus, dass es nicht zwingend notwendig ist, in jedem Datenpfad des Empfängers, in dem eine Rück- oder Derotation der empfan- genen Trainingssequenz durchgeführt wird, eine KanalSchätzung durchzuführen. Die Erfindung verzichtet bewusst auf die Kanalschätzung in diesem frühen Stadium der Detektion der Modulationsart. Stattdessen wird jede empfangene und derotierte Trainingssequenz direkt mit der ursprünglichen, ungefilterten Trainingssequenz verglichen. Der Vergleich erfolgt durch eine Korrelation, d.h. eine Multiplikation der beiden Trainingssequenzen miteinander. Die Modulationsart bestimmt sich danach, welcher Phasenrotationsfaktor in dem jeweiligen Datenpfad bei der Rückrotation und der anschließenden Korrelation ein Maxi- um erzielt.The invention is based on the essential knowledge that it is not absolutely necessary to carry out a channel estimation in each data path of the receiver in which the received training sequence is reversed or derotated. The invention deliberately dispenses with channel estimation at this early stage of the detection of the type of modulation. Instead, each received and derotated training sequence is compared directly with the original, unfiltered training sequence. The comparison is made by a correlation, i.e. a multiplication of the two training sequences with each other. The type of modulation is determined according to which phase rotation factor in the respective data path achieves a maximum during the back rotation and the subsequent correlation.
Dabei ist die Erfindung nicht darauf beschränkt, die üblicherweise in einem Datenburst vorhandene Trainingssequenz in der beschriebenen Weise zu verwenden. Es kann auch im Prinzip jede andere Sequenz von Informationsdaten, die bei der Kommunikation ohnehin übermittelt wird, in der erfindungsgemäßen Weise ausgenutzt werden, um eine Information über die Modulationsart zu übermitteln.The invention is not limited to using the training sequence usually present in a data burst in the manner described. In principle, any other sequence of information data that is transmitted during the communication anyway can be used in the manner according to the invention in order to transmit information about the type of modulation.
Im Gegensatz zu der eingangs erwähnten Druckschrift WOIn contrast to the publication WO mentioned at the beginning
00/10301 benötigt die vorliegende Erfindung keine Kanalschätzungen für die Detektion der Modulationsart, da eine Korrelation zwischen der empfangenen und derotierten Trainingssequenz mit der ursprünglichen, ungefilterten Trainingssequenz durchgeführt wird. Die ursprüngliche Trainingssequenz wird somit vor der Durchführung des Korrelationsschritts nicht einer Kanalfilterfunktion unterworfen. Erfindungsgemäß müssen somit nur eine Anzahl Datenpfade in dem Empfänger bereitgestellt werden, in denen jeweils Derotationen der empfangenen Trainingssequenz um vorgegebene Phasenrotationsfaktoren durchgeführt werden, wobei in jedem Datenpfad im Anschluss an die Derotation eine Korrelation durchgeführt wird, bei welcher die empfangene und derotierte Trainingssequenz mit der ursprünglichen, ungefilterten Trainingssequenz korreliert wird. Eine KanalSchätzung wird erst im Anschluss an die Detektion der Modulationsart durchgeführt .00/10301, the present invention does not require channel estimates for the detection of the type of modulation, since a correlation between the received and derotated training sequence is carried out with the original, unfiltered training sequence. The original training sequence is therefore not subjected to a channel filter function before the correlation step is carried out. According to the invention Thus, only a number of data paths are provided in the receiver, in which derotations of the received training sequence are carried out by predetermined phase rotation factors, with a correlation being carried out in each data path following the derotation, in which the received and deroted training sequence with the original, unfiltered Training sequence is correlated. A channel estimation is only carried out after the detection of the type of modulation.
Ein weiterer Unterschied zu der bereits genannten gattungsbildenden Druckschrift besteht in der Art des mathematischen Vergleichs der Trainingssequenzen. Während bei dem genannten Stand der Technik die zu vergleichenden Trainingssequenzen voneinander subtrahiert werden, wird erfindungsgemäß eine Korrelationsfunktion gebildet. Falls die zeitliche Position der Trainingssequenz innerhalb des empfangenen Datenbursts nur bis zu einer bestimmten Genauigkeit bekannt ist, kann auch vorgesehen sein, dass in jedem Datenpfad die Derotation und Korrelation mehrfach nacheinander durchgeführt wird, wobei die in dem Korrelationsschritt miteinander zu multiplizierenden Trainingssequenzen zeitlich inkrementell gegeneinander verschoben werden und aus diesen mehrfachen Korrelati- onsschritten das maximale Korrelationsergebnis ermittelt wird.Another difference to the generic document mentioned above is the type of mathematical comparison of the training sequences. While the training sequences to be compared are subtracted from one another in the cited prior art, a correlation function is formed according to the invention. If the temporal position of the training sequence within the received data burst is only known to a certain accuracy, provision can also be made for the derotation and correlation to be carried out several times in succession in each data path, the training sequences to be multiplied in the correlation step being incrementally shifted with respect to one another and the maximum correlation result is determined from these multiple correlation steps.
Im folgenden wird die Erfindung anhand eines Ausführungsbei- spiels näher erläutert. Das Ausführungsbeispiel bezieht sich auf die Verwendung der beiden Modulationsarten GMSK (Gaussian minimum shift keying) und 8-PSK (8-ary phase shift keying) .The invention is explained in more detail below on the basis of an exemplary embodiment. The exemplary embodiment relates to the use of the two modulation types GMSK (Gaussian minimum shift keying) and 8-PSK (8-ary phase shift keying).
Die GMSK-Modulation kann durch eine Amplitudenmodulation approximiert und demzufolge wie folgt interpretiert werden:The GMSK modulation can be approximated by an amplitude modulation and therefore interpreted as follows:
1. Ein zugeführtes Bit bk (= 0,1) wird auf ein Symbol ak (= +1,-1) abgebildet, wobei k ein diskretes Zeitmoment bedeutet . 2. Die GMSK-Sy bole a werden mit π/2 Radianten pro Symbol rotiert :1. A supplied bit b k (= 0.1) is mapped onto a symbol ak (= + 1, -1), where k means a discrete moment in time. 2. The GMSK symbols a are rotated with π / 2 radians per symbol:
sk = ej π 2ak = j kak (1)s k = e j π 2 a k = j k a k (1)
3. Die rotierten GMSK-Symbole Sk werden mit einem Impulsfilter gefiltert:3. The rotated GMSK symbols S k are filtered with a pulse filter:
Xk = ∑ iSk-i (2) i=0X k = ∑ iS k -i (2) i = 0
χ ist das modulierte Basisbandsignal, welches mit der gewünschten Trägerfrequenz gemischt und dann zu der Antenne ü- bertragen wird.χ is the modulated baseband signal, which is mixed with the desired carrier frequency and then transmitted to the antenna.
Die 8-PSK-Modulation wird auf ähnliche Weise definiert. Sie unterscheidet sich jedoch von der GMSK-Modulation in der Anzahl der auf ein Symbol abgebildeten Bits und in der Rotation:The 8-PSK modulation is defined in a similar way. However, it differs from GMSK modulation in the number of bits mapped to a symbol and in the rotation:
1. Eine Gruppe von drei zugeführten Bits {b3k, b3k+ι, b3k+2} wird auf ein 8-PSK-Symbol ak = ejnπ/4 (0 < n < 7) abgebildet.1. A group of three supplied bits {b 3 k, b 3k + ι, b 3 k +2 } is mapped onto an 8-PSK symbol a k = e jnπ / 4 (0 <n <7).
2. Die 8-PSK Symbole ak werden mit 3π/8 Radianten pro Symbol rotiert:2. The 8-PSK symbols a k are rotated with 3π / 8 radians per symbol:
sk = e>k3π 8ak (3 )s k = e> k3π 8 a k (3)
3. Die rotierten 8-PSK-Symbole Sk werden mit einem Impulsfil- ter gefiltert:3. The rotated 8-PSK symbols Sk are filtered with an impulse filter:
Xk = Σ h±Sk--i (4)Xk = Σ h ± Sk - i (4)
Ein 8-PSK-Datensymbol enthält somit den dreifachen Informati- onsgehalt wie ein GMSK-Datensymbol. Daher wird die 8-PSK-Mo- dulation für hohe Datenübertragung verwendet, während die GMSK-Modulation für niedrige Datenübertragung verwendet wird.An 8-PSK data symbol therefore contains three times the information content as a GMSK data symbol. Therefore the 8-PSK-Mo- dulation is used for high data transmission, while GMSK modulation is used for low data transmission.
Bei dem EDGE-Standard können beide Modulationsarten verwendet werden und die Modulationsart kann von Burst zu Burst geändert werden. Der EDGE-Empfänger kennt zunächst die Modulationsart nicht, in der die ihm von dem Sender übermittelten Daten moduliert sind. Für jeden Burst erkennt der EDGE-Empfän- ger lediglich einen Block von komplexwertigen Basisband-Ein- gangsdaten xk und muss selbst eine Entscheidung über die verwendete Modulationsart treffen. Diese Herangehensweise wird daher auch als blinde Modulationsdetektion bezeichnet.Both types of modulation can be used with the EDGE standard and the type of modulation can be changed from burst to burst. The EDGE receiver initially does not know the type of modulation in which the data transmitted to it by the transmitter are modulated. For each burst, the EDGE receiver only recognizes a block of complex baseband input data x k and has to make a decision about the type of modulation used. This approach is therefore also called blind modulation detection.
Erfindungsgemäß wird dem ausgesendeten Signal eine Informa- tion über die verwendete Modulationsart aufgeprägt und hierfür die dem Empfänger bekannte vorgegebene Trainingssequenz verwendet, die in jedem GSM/EDGE-Burst enthalten ist. Die Datensymbole der Trainingssequenz werden senderseitig mit einem Phasenrotationsfaktor rotiert, der auch für die Modulation der Nutzsignale eingesetzt wird, wobei prinzipiell hierfür auch ein anderer Phasenrotationsfaktor eingesetzt werden kann.According to the invention, information about the type of modulation used is impressed on the transmitted signal and the predetermined training sequence known to the receiver, which is contained in each GSM / EDGE burst, is used for this purpose. The data symbols of the training sequence are rotated on the transmitter side with a phase rotation factor which is also used for the modulation of the useful signals, although in principle another phase rotation factor can also be used for this.
In der einzigen Zeichnungsfigur ist dieses Ausführungsbei- spiel für das erfindungsgemäße Verfahren der blinden Modulationsdetektion schematisch dargestellt.This exemplary embodiment of the blind modulation detection method according to the invention is shown schematically in the single drawing figure.
Die Figur zeigt das Ablaufschema für die blinde Modulationsdetektion in einem Empfänger. Aus einer empfangenen Trai- ningssequenz xk werden zwei Proben (Samples) erzeugt und in zwei Datenpfade entsprechend der beiden Modulationsarten eingespeist. In der Figur bezeichnet %k (k = 1, 2, ... , N) die empfangene Trainingssequenz. N bezeichnet die Länge der Trainingssequenz. tk (k = 1, 2, ... , N) bezeichnet die ursprüng- liehe Trainingssequenz, welche in dem Empfänger gespeichert ist. In den Datenpfaden wird zunächst die empfangene Trainingssequenz Xk um -π/2 pro Symbol bei GMSK und um -3π/8 pro Symbol bei 8-PSK derotiert.The figure shows the flow diagram for blind modulation detection in a receiver. Two samples (samples) are generated from a received training sequence xk and fed into two data paths according to the two types of modulation. In the figure,% k (k = 1, 2, ..., N) denotes the received training sequence. N denotes the length of the training sequence. t k (k = 1, 2, ..., N) denotes the original training sequence, which is stored in the receiver. In the data paths, the received training sequence Xk is first derotated by -π / 2 per symbol for GMSK and by -3π / 8 per symbol for 8-PSK.
Nach der Derotation wird die empfangene und jeweils derotierte Trainingssequenz yk mit der ursprünglichen Trainingssequenz tk korreliert. Da die Korrelation aufgrund der unbekannten Phase des Signals komplexwertig sein kann, wird nach der Summation über die Produkte bei den einzelnen Zeitmomen- ten k die quadratische Magnitude der Korrelation berechnet.After derotation, the received and each derotated training sequence y k with the original training sequence correlates t k. Since the correlation can have a complex value due to the unknown phase of the signal, the quadratic magnitude of the correlation is calculated after the summation over the products at the individual time moments k.
Schließlich wird das Korrelationsergebnis zwischen GMSK und 8-PSK verglichen. Falls die empfangene und derotierte Trainingssequenz yk GMSK eine stärkere Ähnlichkeit mit der ur- sprünglichen Trainingssequenz tk als die empfangene und derotierte Trainingssequenz yk 8PSK aufweist, d.h. C GMSK > C 8PSK ^ wj_rcj detektiert, dass der entsprechende Datenburst mit der Modulationsart GMSK moduliert ist. Andernfalls wird detektiert, dass die Modulationsart 8-PSK ist.Finally, the correlation result between GMSK and 8-PSK is compared. If the received and deroted training sequence y k GMSK is more similar to the original training sequence t k than the received and deroted training sequence y k 8PSK , ie C GMSK > C 8PSK ^ w j_ rc j detects that the corresponding data burst with the Modulation type GMSK is modulated. Otherwise it is detected that the modulation type is 8-PSK.
Nach dieser blinden Modulationsdetektion kann der Demodulator dann mit der KanalSchätzung beginnen.After this blind modulation detection, the demodulator can then begin channel estimation.
Aufgrund der Tatsache, dass Unsicherheiten über die zeitliche Lage der empfangenen Trainingssequenz innerhalb des Daten- bursts bestehen können, kann vorgesehen sein, dass die Korrelation in jedem Datenpfad mehrfach nacheinander ausgeführt wird, indem die miteinander zu korrelierenden Trainingssequenzen zeitlich gegeneinander verschoben werden. Es kann al- so zunächst auf der Basis bestimmter Annahmen über die zeitliche Lage der Trainingssequenz eine erste Korrelation in jedem Datenpfad durchgeführt werden. Anschließend können die Datensymbole der zu korrelierenden Sequenzen tk und yk erneut dem Korrelator zugeführt werden und geringfügig gegeneinander versetzt werden. Von mehreren solcherart ausgeführten Korrelationen wird dann das Maximum ausgewählt. Das erfindungsgemäße Verfahren zur automatischen Erkennung der verwendeten Modulationsart zeichnet sich durch eine hohe Treffsicherheit mit einem im Vergleich zum Stand der Technik geringen Aufwand aus . Due to the fact that there may be uncertainties regarding the temporal position of the received training sequence within the data burst, it can be provided that the correlation in each data path is carried out several times in succession by shifting the training sequences to be correlated with one another in time. A first correlation can therefore first be carried out in each data path on the basis of certain assumptions about the temporal position of the training sequence. The data symbols of the sequences t k and y k to be correlated can then be fed to the correlator again and slightly offset from one another. The maximum is then selected from several correlations carried out in this way. The method according to the invention for automatic detection of the type of modulation used is characterized by a high degree of accuracy with little effort compared to the prior art.

Claims

Patentansprüche claims
1. Sende- und Empfangsverfahren in einem digitalen Telekommunikationssystem, bei welchem - senderseitig jedes Datensymbol einer vorgegebenen, dem Empfänger bekannten Ausgangssequenz (tk) , insbesondere der Trainingssequenz eines Datenbursts, um einen für die verwendete Modulationsart spezifischen Phasenrotationsfaktor rotiert wird, und - empfängerseitig die Datensymbole um verschiedene Phasenrotationsfaktoren rück- oder derotiert werden und die dadurch erhaltenen Sequenzen (yk) mit der Ausgangssequenz (tk) verglichen werden, dadurch gekennzeichnet , dass - empfängerseitig der Vergleich in der Weise durchgeführt wird, daß zwischen den erhaltenen Sequenzen (yk) und der Ausgangssequenz (tk) eine Korrelationsfunktion gebildet wird.1.Sending and receiving methods in a digital telecommunication system, in which - each data symbol of a given output sequence (tk) known to the receiver, in particular the training sequence of a data burst, is rotated by a phase rotation factor specific to the type of modulation used, and - the data symbols on the receiver side are reversed or derotated by different phase rotation factors and the sequences (y k ) thus obtained are compared with the starting sequence (t k ), characterized in that - on the receiver side, the comparison is carried out in such a way that between the sequences (y k ) obtained and a correlation function is formed from the output sequence (tk).
2. Sende- und Empfangsverfahren nach Anspruch 1, dadurch gekennzeichnet , dass die Korrelationsfunktion zwischen den erhaltenen Sequenzen und der ursprünglichen, ungefilterten Ausgangssequenz gebildet wird.2. Transmitting and receiving method according to claim 1, characterized in that the correlation function is formed between the sequences obtained and the original, unfiltered output sequence.
3. Sende- und Empfangsverfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet , dass die verwendete Modulationsart auf der Basis des Maximums der Korrelationsfunktion detektiert wird.3. Transmitting and receiving method according to claim 1 or 2, characterized in that the type of modulation used is detected on the basis of the maximum of the correlation function.
4. Sende- und Empfangsverfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet , dass die Korrelationsfunktion mehrmals hintereinander gebildet wird und dabei die erhaltenen Sequenzen und die Ausgangs- sequenz zeitlich gegeneinander verschoben werden. 4. Transmitting and receiving method according to one of the preceding claims, characterized in that the correlation function is formed several times in succession and the sequences obtained and the output sequence are shifted in time with respect to one another.
5. Empfänger eines digitalen Telekommunikationssystems, welcher aufweist:5. Receiver of a digital telecommunication system, which has:
Mittel zum Empfangen eines von einem Sender übersandten Datensignals, welches eine dem Empfänger bekannte Ausgangsse- quenz enthält, in welcher jedes Datensymbol um einen Phasenrotationsfaktor rotiert ist,Means for receiving a data signal transmitted by a transmitter, which contains an output sequence known to the receiver, in which each data symbol is rotated by a phase rotation factor,
Mittel zum Derotieren der Datensymbole der empfangenen Ausgangssequenz um verschiedene Phasenrotationsfaktoren, gekennzeichnet durch - Mittel zum Bilden von Korrelationsfunktionen zwischen den erhaltenen und rückrotierten Sequenzen und der Ausgangs- sequenz, insbesondere der ursprünglichen ungefilterten Ausgangssequenz . Means for derotating the data symbols of the received output sequence by various phase rotation factors, characterized by - means for forming correlation functions between the received and back-rotated sequences and the output sequence, in particular the original unfiltered output sequence.
EP02771624A 2001-05-21 2002-05-06 Recognition of modulation type by means of a marked phase rotation factor of a training sequence Ceased EP1391093A1 (en)

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Families Citing this family (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7406139B2 (en) * 2003-06-16 2008-07-29 Broadcom Corporation System and method to identify a modulation format of a data frame within a cellular wireless network
US7916811B2 (en) * 2004-02-11 2011-03-29 General Instrument Corporation Method and apparatus for improved burst acquisition in a digital receiver
US7830975B2 (en) * 2004-04-12 2010-11-09 Nokia Corporation I/Q MIMO detection for single antenna interference cancellation
US8107560B2 (en) * 2004-05-12 2012-01-31 Telefonaktiebolaget Lm Ericsson (Publ) Method and apparatus for interference cancellation in communication signal processing
JP4256301B2 (en) * 2004-05-28 2009-04-22 株式会社東芝 Wireless communication device
FR2875358B1 (en) 2004-09-15 2006-12-15 Eads Telecom Soc Par Actions S INSERTING A SECONDARY FLOW OF BINARY INFORMATION IN A MAIN FLOW OF SYMBOLS OF DIGITAL MODULATION
US7382846B1 (en) * 2004-09-29 2008-06-03 Rockwell Collins, Inc. Off-symbol correlation technique
KR100611507B1 (en) * 2005-02-07 2006-08-11 삼성전자주식회사 Blind detection method and apparatus, and mobile communication receiver having the same
US7697638B2 (en) * 2005-08-16 2010-04-13 Freescale Semiconductor, Inc. Modulation detection in a SAIC operational environment
US7894551B2 (en) * 2005-08-29 2011-02-22 Mediatek Inc. Modulation scheme detecting apparatus and related method
US7724816B2 (en) * 2005-09-13 2010-05-25 Freescale Semiconductor, Inc. Dynamic switching between maximum likelihood sequence estimation (MLSE) and linear equalizer for single antenna interference cancellation (SAIC) in a global system for mobile communications (GSM) system
US8300721B2 (en) * 2007-03-14 2012-10-30 Agilent Technologies, Inc. Pseudorandom noise code acquisition in direct sequence spread spectrum systems
CN101321315B (en) * 2007-06-08 2011-09-14 华为技术有限公司 Method and device for transmitting and receiving signal
US7881365B2 (en) * 2007-10-31 2011-02-01 Agere Systems Inc. Demodulator with configurable adaptive equalizer
EP2540043B1 (en) * 2010-02-26 2014-01-01 Telefonaktiebolaget LM Ericsson (publ) Method and arrangement to jointly reduce peak to average power ratio and signal modulation type for pre-coded enhanced general packet radio service (egprs)
US9374166B2 (en) * 2012-02-13 2016-06-21 Ciena Corporation High speed optical communication systems and methods with flexible bandwidth adaptation
WO2018172552A1 (en) 2017-03-24 2018-09-27 Telefonaktiebolaget Lm Ericsson (Publ) Detection of inconsistent data in a data transmission

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2021361C (en) 1989-07-17 1994-03-29 Hiroyasu Muto Quadrature demodulation of a data sequence following a particular signal sequence with a local reference carrier signal having a frequency different from a received carrier signal
US5289476A (en) * 1991-05-10 1994-02-22 Echelon Corporation Transmission mode detection in a modulated communication system
US6473506B1 (en) * 1998-10-13 2002-10-29 Telefonaktiebolaget Lm Ericsson (Publ) Signaling using phase rotation techniques in a digital communications system
US6463107B1 (en) * 1999-07-01 2002-10-08 Telefonaktiebolaget Lm Ericsson (Publ) Methods and apparatuses for synchronization and modulation type detection
FI110825B (en) * 1999-08-10 2003-03-31 Nokia Corp A method for selecting a modulation detector at a receiver and a receiver
US6400928B1 (en) * 1999-11-19 2002-06-04 Telefonaktiebolaget L M Ericsson (Publ) Method and system for blind detection of modulation

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO02096051A1 *

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