EP2067260A1 - Procede pour deriver des signaux parasites a partir de signaux numeriques modules - Google Patents

Procede pour deriver des signaux parasites a partir de signaux numeriques modules

Info

Publication number
EP2067260A1
EP2067260A1 EP06806864A EP06806864A EP2067260A1 EP 2067260 A1 EP2067260 A1 EP 2067260A1 EP 06806864 A EP06806864 A EP 06806864A EP 06806864 A EP06806864 A EP 06806864A EP 2067260 A1 EP2067260 A1 EP 2067260A1
Authority
EP
European Patent Office
Prior art keywords
signals
modulated digital
digital signals
transmitted
modulated
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
EP06806864A
Other languages
German (de)
English (en)
Inventor
Lukas Pauk
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.)
Atos Convergence Creators GmbH
Original Assignee
Siemens AG Oesterreich
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG Oesterreich filed Critical Siemens AG Oesterreich
Publication of EP2067260A1 publication Critical patent/EP2067260A1/fr
Ceased legal-status Critical Current

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Classifications

    • 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
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
    • H04B1/1027—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal

Definitions

  • the invention relates to a method for deriving interference signals from modulated digital signals, wherein each signal from digital data to be transmitted is determined on the basis of a modulation scheme and the modulated digital signals received at a receiver side comprise interfering signals in addition to the transmitted, modulated digital signals.
  • a signal in the sense of communications technology is a physical variable whose parameters are suitably changed so that the signal can become the carrier of information, it being possible to distinguish between so-called analog signals and so-called digital signals.
  • the information of the signal is stored in the amplitude.
  • this may be e.g. only two values such as "on and off", "0 and 1", etc., the signal is also referred to as a digital signal.
  • digitization for example, information such as text, image, sound, etc. in a digital, so countable, form - that is, in general, the information is converted by means of a binary code into digital data.
  • digitization is also the conversion of an analog physical quantity (eg electrical voltage, brightness, pressure, etc.) into discrete, digitally represented numerical values.
  • Digital signals digital data
  • transmission channel eg lines, air interface, etc.
  • square waves of which digital signal sequences of eg zeros and ones can be ideally represented, or be forwarded similar ideal pulse shape.
  • the digital signal is due to Storein bathe (eg, steaming, Storsignale, etc.) on the transmission channel, which is understood to be an established point-to-point connection, which is suitable for the transmission of signals or data over spatial or temporal distance is so distorted that the data may arrive at a receiver in a distorted manner and can no longer be correctly decoded.
  • Storein bathe eg, steaming, Storsignale, etc.
  • analog signals can be transmitted over long distances depending on the respective frequency. Therefore, digital signals are mapped by a so-called digital modulation on analog signals, which are also referred to as Tragerfrequenz or as a carrier. Usually, e.g. Sinus oscillations used as Tragerfrequenzen.
  • amplitude modulation In the case of amplitude modulation (ASK), the amplitude of a usually high-frequency carrier frequency is changed depending on the (low) frequency signals to be transmitted, which are to be modulated.
  • digital amplitude modulation for example, the carrier frequency is transmitted through the digital signals on the transmission channel on and off.
  • ASK was used at the beginning of broadcast technology because such modulated signals are very easy to generate and demodulate.
  • quadrature amplitude modulation can be used.
  • FSK frequency modulation
  • Phase modulation less prone to interference.
  • frequency modulation in the simplest case - the so-called binary FSK, the digital zero is encoded by an analog oscillation of a frequency and the digital one by an analog oscillation of a second frequency, the value of each frequency being a certain discrete value (eg zero or zero). One) corresponds.
  • the frequencies are arranged symmetrically about a carrier frequency. The distance between carrier frequency and signal frequency is called frequency sweep.
  • the FSK is technically usually e.g. realized by means of two oscillators, which are alternately turned on and off, but the changing phase position in the output signal is a disadvantage.
  • FSK is e.g. used in telecommunications in the transmission of data via lines, but also in the radio.
  • phase modulation digital signals - e.g. binary zeros and ones - coded by analogue oscillations of constant amplitudes and frequency, but different phase, so that the phase of the carrier frequencies for
  • QPSK Phase Shift Keying
  • QPSK can simultaneously transmit 2 bits per symbol, doubling the use of available bandwidth.
  • QPSK is used for signal transmission in digital satellite channels, in terrestrial broadcasting of digital signals and also in wired transmission methods.
  • Quadrature Amplitude Modulation combines Amplitude Modulation (ASK) and Phase Modulation (PSK), i. the carrier frequency is modulated in amplitude and phase.
  • QAM is particularly suitable for transmitting high data rates and is robust against so-called phase errors.
  • PSK Phase Modulation
  • QAM is also paid to the so-called linear digital modulation method.
  • amplitude modulation e.g., amplitude modulation (ASK)
  • Frequency Modulation (FSK), Phase Modulation (PSK), Quadrature Phase Modulation (QAM), etc.) it is then possible, over a certain transmission channel, which characterized by a transmission medium used (eg copper cable, coaxial cable, air, etc.) and a so-called bandwidth is going to transmit a certain data rate.
  • a transmission medium used eg copper cable, coaxial cable, air, etc.
  • the signals generated by means of the respective digital modulation which are derived from the digital signals or digital data, can also be referred to as modulated digital signals.
  • these modulated digital signals can be negatively influenced by so-called interference signals.
  • Such disturbing signals which affect the transmission of the (digital) information or data imaged in the modulated digital signals are, for example, noise or interference.
  • Noise is understood to mean several unwanted and long-lasting disturbances caused by different causes, which are superimposed on the (useful) signal to be transmitted.
  • radio transmissions such as atmospheric, galactic or cosmic noise, which is generated by ionization processes and inhomogeneities of the atmosphere and by radiation sources in or in space. This noise is frequency, weather and year-dependent.
  • interferences Under interferences usually a superposition of waves - in telecommunications, e.g. of electromagnetic waves as a function of a distribution of the frequencies or wavelengths in the signals understood.
  • waves In the case of interference, it is possible to distinguish between a so-called constructive interference, in which the superimposing waves reinforce each other, and a so-called destructive interference, in which the superimposed waves mutually evaporate or even extinguish.
  • interferences in the transmission of (useful) signals such as e.g. modulated digital signals and significantly affect the quality of the transmitted digital data.
  • Interference which may also include noise, is a common problem in radio technology in particular, if these interferences are also present within a so-called frequency band of the carrier frequency, for example.
  • Tragerfrequenzen occur, being referred to as the frequency band that area of the electromagnetic spectrum used for technical communication, which is associated with an electromagnetic wave (eg Tragerfrequenz) according to their frequency and wavelength.
  • bandwidth The difference between two frequencies, of which a certain, continuously related frequency range - ie a frequency band - is formed, is referred to as bandwidth.
  • satellite communications interference may occur, for example, from adjacent satellite transmissions, locally received terrestrial signals, or unauthorized transmission.
  • the carrier frequencies of these other transmissions eg, adjacent satellite transmissions, etc.
  • generate interference signals such as interference in a frequency band, which is associated with a different carrier frequency and thus interferes with the transmission of modulated digital signals in that frequency band.
  • Carrier frequencies used for the transmission of signals in a frequency band assigned to them are also referred to as regular carrier frequencies with respect to this frequency band.
  • Carrier frequencies, from which, for example, disturbance signals are triggered in non-assigned frequency bands, can also be referred to as unauthorized or unauthorized carrier frequencies with respect to these frequency bands. But even between carrier frequencies of a frequency band (such as the PSK), it can lead to interference signals such as interference.
  • EVM Error Vector Magnitude
  • Error Vector can be used to assess the quality of a modulation type or a so-called demodulator, but also to filter out interferences on the receiver side.
  • the error vector is usually calculated by means of a so-called demodulator by subtracting a so-called reference signal from an input signal measured on the receiver side.
  • the reference signal is thereby obtained on the receiver side from the demodulated, digital data, wherein these demodulated, digital data pass through a filter by which is usually simulated the transmission link. That is, the reference signal is thus an output of a filter which corresponds to, for example, a combination of a modulation filter used on a transmitter side in the modulation and a demodulation filter which corresponds to the filter used in the demodulation of the modulated digital signal on the receiver side.
  • the measured input signal, which is subtracted from the reference signal is also evaluated in the demodulator by a measurement filter. For example, this measuring filter also corresponds to the demodulation filter. This means that in the calculation of the error vector for both the determination of the reference signal and when measuring the input signal, a filtering of the respective signal is performed.
  • matched or signal matched filters are usually used, which has such a (adapted) transmission function that an additively disturbed (useful) signal can be detected as reliably as possible.
  • a matched filter is concentrated on the bandwidth of the regular carrier frequency or regular carrier frequencies and operates only in the range of the signal rate.
  • bandpass filters from which interference signals outside the frequency band of the modulated, digital signals are suppressed.
  • a filter in which, for example, the transfer function of the demodulation filter is included, is traversed, the error vector is influenced by this filtering.
  • interference signals whose bandwidths are not completely within the frequency band of the regular carrier frequency or carrier frequencies are also affected by the filtering and therefore can only be determined to a limited extent or not at all with the help of the Error Vector calculation.
  • significant portions of a spectrum of the interfering signal may be truncated by the filtering, thereby providing, for example, demodulation or identification of the signal
  • Interfering signal or e.g. an estimation of the central frequency, bandwidth and power of the interfering signal is made impossible.
  • a problem of the error-vector calculation is also that the Error-Vector only in so-called linear digital modulation methods such. PSK, Q-PSK, QAM, etc. can be used for deriving interference signals.
  • the document US 2003/0165205 A1 describes a method and a device for measuring and demodulating interferences that are contained in a digital carrier.
  • the interferences are determined with the aid of an error vector, which is generated by a so-called blind equalizer demodulator.
  • the received signals on the basis of which the error vector is calculated and thus the interferences are determined, likewise pass through a filter in the so-called receiver.
  • digital signals generated from the received signals are filtered again in order to limit them to the bandwidth of the signals in the baseband.
  • the method described in document US 2003/0165205 has similar disadvantages as an estimation of interference signals by means of error vector calculation. By filtering, e.g. cut off significant portions of the spectrum of an interfering signal, whereby only those interfering signals which are within the frequency band of the regular carrier frequency or the regular carrier frequencies can be identified.
  • the present invention is therefore based on the object to provide a method which is a derivative of all a transmission of modulated interference signals influencing digital signals - even those which are not completely located in the frequency band of one or more regular carrier frequencies of the modulated digital signals, and which is not only applicable to linear digital modulation methods.
  • the main aspect of the proposed solution according to the invention is that the estimation of the interference signals - in particular those interference signals whose bandwidths are not completely within the frequency band of the regular carrier frequency or carrier frequencies, without influencing filtering - such. through a matched filter, e.g. the demodulation filter, since on the receiver side neither of the received, modulated digital signals nor of the reconstruction of the transmitted, modulated digital signals is a filter in which e.g. the transmission function of the demodulation filter is included, is passed through. Therefore, it is advantageously possible to identify sources of the disturbing signals on the receiver side on the basis of the estimated disturbing signals or to estimate the central frequency, bandwidth and power of a disturbing signal.
  • a matched filter e.g. the demodulation filter
  • inventive method advantageously not only in linear digital modulation such as PSK, Q-PSK, QAM, etc., but generally in digital Modulation can be used for a derivation of Storsignalen.
  • the transmitted, modulated digital signals are reconstructed on the receiver side on the basis of the values of the digital data to be transmitted on the receiver side, because in a simple manner a modulation of the digital data on a transmitter side - i. a transmitter-side conversion of the digital data into modulated digital signals - can be simulated on the receiver side and thus from the reconstruction of the transmitted, modulated digital signal, a good estimate of the modulated digital signals sent by the transmitter is delivered.
  • Time delay are taken into account by the transmission channel, because even the received modulated digital signals by parameters of the transmission channel such. Damping, time shift, etc. are influenced.
  • the received signals s r as s r As mi (c, t - t d ) + s ai (t), where A is the attenuation of the Transmission channel, c the digital data to be transmitted, t d the time delay of the transmission channel and s a i (t) denote the interfering signals, and on the receiver side the reconstruction of the transmitted, modulated digital signals 'iX as * " * "" ' , where A the estimate of
  • Attenuation c represent the values of the digital data to be transmitted at the receiver side and ' ⁇ ' the estimation of the time shift.
  • the corresponding digital data and influencing parameters of the transmission channel such as attenuation and time shift, are thus taken into account in an advantageous manner.
  • modulated digital signals s r and the interference signals are also taken into account.
  • the interference signals can be demodulated and / or identified.
  • FIG. 1 shows the sequence of the method for deriving interference signals from modulated digital signals in an exemplary manner.
  • a modulated digital signal s m is generated by a digital modulation (eg PSK, Q-PSK, QAM, etc.) on the basis of a modulation scheme of digital data to be transmitted.
  • Each of the modulated digital signals s mi corresponds to certain data c, wherein the modulated digital signals s mi can also be represented as functions s mi (c, t) with the parameters c and t for a time course and it is assumed that the Signals s mi (c, t) are, for example, interference-free or ideal.
  • the modulated digital signals s mi (c, t) are converted to a transmission frequency before transmission. That is, the signals s mi (c, t) are of a carrier frequency, which is usually in the so-called baseband - ie in the frequency range of their
  • Original position - is, to another carrier frequency (for example, in radio technology to the so-called radio frequency) implemented.
  • another carrier frequency for example, in radio technology to the so-called radio frequency
  • the modulated digital signals s mi (c, t) are then transmitted via a transmission channel (eg lines, air interface, etc.) to a receiver.
  • the signals s mi (c, t) are influenced depending on the transmission medium used (eg copper cable, coaxial cable, air, etc.). It can come through the transmission channel at a time delay t d and a damping A, under which an undesirable loss of energy of a signal in a transmission of a Sender is understood to a receiver.
  • disturbances such as noise, interference, etc. of the signals s m i (c, t) may occur.
  • a received, modulated digital signal s r is first downconverted from the transmission frequency, for example, to the baseband of the carrier frequency on a receiver side.
  • the received, modulated digital signal s r comprise, in addition to the transmitted, modulated digital signal s m i (c, t) with the index i, this signal s m ⁇ has been influenced by damping A and time shift t d of the transmission channel, also interference signals s' a i (t).
  • the received, modulated digital signal s r On the receiver side, the received, modulated digital
  • a sixth method step 6 the received, modulated, digital signal s r is demodulated.
  • the demodulator block in a seventh method step 7 from the i-th transmitted modulated digital signal s m ⁇ , which is contained in time-shifted and subdued form in the signal s r , estimates c for the digital data c, ⁇ for the damping A of
  • a reconstruction s m ⁇ of the transmitted, modulated digital signal s m ⁇ is derived from these estimates c, ⁇ and ⁇ d .
  • the reconstruction s m ⁇ can for example be given by the formula .v ,. ( ⁇ to be discribed.
  • Method step 9 then becomes the reconstruction s m ⁇ of the transmitted, modulated digital signal s m ⁇ from the in
  • Subtracts signal s r By this subtraction is in a tenth step 10 according to a formula an estimate s a ⁇ the interference signals with the index i determined.
  • no filter transfer function is included, since on the receiver side neither from the received, modulated digital signal s r nor from the reconstruction s m ⁇ of the transmitted, modulated digital signal s m ⁇ a filter in which, for example, the transfer function of a demodulation or is passed through a so-called matched filter.
  • the value of the difference So (t) is approximated to zero with increasing estimation accuracy.
  • This procedure of method steps 5 to 10 can be repeated for all modulated, digital signals s m ⁇ accordingly and the corresponding reconstruction s m i can be found.
  • the demodulator block must be set so that the respective modulated, digital signal s m ⁇ demodulated always, so that the associated estimates c, ⁇ and ' f ⁇ * are found.
  • the constants c, A and t d as well as their estimates for each signal s m ⁇ can differ with different index i. Therefore, the constants c, A and t d as well as their estimates should be distinguished by the index i.
  • an estimate s a of the Storsignale be determined, being approximated with increasing estimation quality So (t) zero.
  • this formula for estimating s a of the Storsignale no filter-transfer function of a demodulation filter is included, because neither the received, modulated digital signal s r nor the reconstruction s mi of the transmitted, modulated digital signal s mi a filter in which, for example, the Transmission function of a demodulation filter or, a so-called matched filter is included, are traversed.
  • the estimation s a of the interference signals is therefore also without interference from filtering and therefore suitable for identifying, for example, interference from unauthorized carrier frequencies.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Noise Elimination (AREA)

Abstract

L'invention concerne un procédé pour dériver des signaux parasites à partir de signaux numériques modulés. Les signaux numériques modulés émis par un émetteur sont alors reconstruits du côté du récepteur. Ces signaux numériques modulés reconstruits sont alors soustraits des signaux numériques modulés reçus et les signaux parasites sont estimés du côté du récepteur à partir du résultat de la soustraction sans influence par le filtrage précédent. Les signaux parasites estimés du côté du récepteur permettent de déterminer, par exemple par démodulation, les éventuelles fréquences porteuses non autorisées qui viennent perturber les fréquences porteuses normales, même lorsque les signaux parasites ne se trouvent pas entièrement dans la bande passante de la ou des fréquences porteuses normales.
EP06806864A 2006-09-28 2006-09-28 Procede pour deriver des signaux parasites a partir de signaux numeriques modules Ceased EP2067260A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2006/066837 WO2008037297A1 (fr) 2006-09-28 2006-09-28 Procédé pour dériver des signaux parasites à partir de signaux numériques modulés

Publications (1)

Publication Number Publication Date
EP2067260A1 true EP2067260A1 (fr) 2009-06-10

Family

ID=38050211

Family Applications (1)

Application Number Title Priority Date Filing Date
EP06806864A Ceased EP2067260A1 (fr) 2006-09-28 2006-09-28 Procede pour deriver des signaux parasites a partir de signaux numeriques modules

Country Status (6)

Country Link
US (1) US8223907B2 (fr)
EP (1) EP2067260A1 (fr)
BR (1) BRPI0622028A2 (fr)
CA (1) CA2660808C (fr)
IL (1) IL196953A (fr)
WO (1) WO2008037297A1 (fr)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3586348B2 (ja) 1997-03-05 2004-11-10 富士通株式会社 信号対干渉電力比測定装置及び信号対干渉電力比測定方法並びにｃｄｍａ通信方式下での送信電力制御方法
JP3872953B2 (ja) * 1999-12-27 2007-01-24 株式会社東芝 アダプティブアンテナを用いた無線通信装置
AU2003213579B2 (en) 2002-03-04 2008-11-13 Glowlink Communications Technology Detecting and measuring interference contained within a digital carrier

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2008037297A1 *

Also Published As

Publication number Publication date
WO2008037297A1 (fr) 2008-04-03
CA2660808A1 (fr) 2008-04-03
IL196953A0 (en) 2009-11-18
US8223907B2 (en) 2012-07-17
US20100119021A1 (en) 2010-05-13
IL196953A (en) 2013-07-31
BRPI0622028A2 (pt) 2014-04-22
CA2660808C (fr) 2016-01-19

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