FR2973613A1 - Method for detecting an interference frequency band in a very broadband frequency radio signal, device and receiver therefor - Google Patents

Method for detecting an interference frequency band in a very broadband frequency radio signal, device and receiver therefor Download PDF

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Publication number
FR2973613A1
FR2973613A1 FR1152752A FR1152752A FR2973613A1 FR 2973613 A1 FR2973613 A1 FR 2973613A1 FR 1152752 A FR1152752 A FR 1152752A FR 1152752 A FR1152752 A FR 1152752A FR 2973613 A1 FR2973613 A1 FR 2973613A1
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Prior art keywords
frequency
radio signal
frequency band
band
according
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FR1152752A
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French (fr)
Inventor
Ekome Stephane Mebaley
Jean Schwoerer
Genevieve Baudoin
Martine Villegas
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Orange SA
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Orange SA
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Priority to FR1152752A priority Critical patent/FR2973613A1/en
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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details 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
    • H04B1/69Spread spectrum techniques
    • H04B1/7163Spread spectrum techniques using impulse radio
    • H04B1/719Interference-related aspects
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details 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
    • H04B1/06Receivers
    • H04B1/10Means associated with receiver for limiting or suppressing noise or interference induced by transmission
    • H04B1/1027Means associated with receiver for limiting or suppressing noise or interference induced by transmission assessing signal quality or detecting noise/interference for the received signal
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details 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
    • H04B1/06Receivers
    • H04B1/10Means associated with receiver for limiting or suppressing noise or interference induced by transmission
    • H04B1/1027Means associated with receiver for limiting or suppressing noise or interference induced by transmission assessing signal quality or detecting noise/interference for the received signal
    • H04B1/1036Means associated with receiver for limiting or suppressing noise or interference induced by transmission assessing signal quality or detecting noise/interference for the received signal with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters

Abstract

The invention relates to a method for detecting an interfering frequency band for a radio signal received by a receiver with a very wide frequency band, characterized in that it comprises a step of locating said interfering frequency band comprising the sub-frequencies. next steps: selecting a plurality of filter frequencies in the frequency band of the radio signal, two by two distant by a predetermined pitch; for each selected filtering frequency, control of filtering the radio signal using a band filter of predetermined width, at least equal to said pitch and centered on said filtering frequency; o obtaining an energy level of the filtered radio signal; o comparison of the energy level obtained and a reference energy level; identifying a central frequency of the interfering frequency band among the selected filtering frequencies, according to said comparison, according to a minimum residual energy criterion.

Description

FIELD OF THE INVENTION The field of the invention is that of telecommunications, more precisely telecommunications by radio link. Ultra Wide Band (UWB) and radio receivers with very wide frequency bands. The present invention is applicable to all types of networks using UWB radio technology, in particular sensor networks, personal area networks (PANs) or personal networks ("Body"). Area Networks "or BAN, in English). The frequency band allocated to UWB signals ranges from 3.1 to 10.6 GHz. This very broad spectrum of frequencies is shared with multiple narrowband services. However, a UWB signal natively has a low energy level. Its transmission is therefore very sensitive to the simultaneous transmission of a signal emanating from a narrow-band service in the UWB signal band of interest, since this simultaneous transmission causes interference, called narrow-band interference ("Narrowband"). interference "or NBI), which degrade the quality of the transmitted UWB signal by increasing the Bit Error Rate (BER) for a given transmission power of the UWB signal. Such degradation is particularly sensitive with a receiver comprising a non-coherent energy detector ("non-coherent Energy Detector" or ED, in English) based on a quadratic law. An energy detector achieves worse performance than a coherent receiver, but it has the advantage of offering a simplified architecture to the receiver, low cost and reasonable consumption, well adapted to the constraints of the applications targeted by the personal networks PAN, carried on oneself BAN or more generally the networks of sensors. In relation to FIG. 1, the principle of a UWB radio receiver IR (Impulse Radio) comprising such a DET detector is schematically presented. The radio signal is received by an antenna A, then filtered by a FB (notch filter) band filter centered on a fixed frequency fB. The filtered signal is then transmitted to an amplifier LNA ("Low Noise Amplifier"). In particular, the band filter makes it possible to avoid saturation of the LNA amplifier. The amplified signal is again filtered, this time by a bandpass filter BPF ("Band Pass Filter"). The assembly formed by the antenna, the amplifier and the filtering means constitute a front-end RF ("radio frequency", in English) EFRF. The processed signal is then presented to the non-coherent DET energy detector, which comprises a detection module MD of a quantity of quadratic energy received, an integration module MI of the quadratic energy detected on a symbol time and a DEC decision module is able to make a decision when to the value of the symbol received. It is understood that such a receiver is able to suppress narrowband interference provided that they are located around the center frequency of the band filter. A disadvantage of this method is that it requires prior knowledge of the center frequency of the narrow-band interference band, which is impossible with a non-coherent energy detector. The invention improves the situation. 2. DISCLOSURE OF THE INVENTION The invention relates to a method for detecting an interfering frequency band for a radio signal received by a receiver with a very broad frequency band, characterized in that it comprises a phase of localization of said interfering frequency band comprising the following steps: - 1) selecting a plurality of filter frequencies in the frequency band of the radio signal, two by two distant by a predetermined pitch; - 2) for each selected filtering frequency, - control of filtering the radio signal using a band filter of predetermined width, at least equal to said pitch and centered on said filtering frequency; obtaining an energy level of the filtered radio signal; - comparison of the energy level obtained at a reference energy level; - 3) identifying a central frequency of the interfering frequency band 30 among the selected filter frequencies, according to said comparison, according to a minimum residual energy criterion. According to the invention, a band filter is successively applied to different selected filter frequencies in the frequency band of the signal, so that the entire band is scanned and filtered. For each application of the band filter, the residual energy of the radio signal after filtering is compared with a reference energy level of the received signal. The filtering frequency to best satisfy a minimum residual energy criterion is identified as the center frequency of the interfering frequency band. Its width is estimated to be less than or equal to that of the band filter used to suppress at least a large part of the desired narrow-band interference frequency band. Thus, the invention is based on an entirely new and inventive approach to the detection of an interfering frequency band in an ultra wide band signal, based on the detection of a very large amount of energy provided by this signal. interfering band with respect to the average energy level of the ultra-wideband signal and on a constant energy assumption of the useful radio signal and the white noise present in the signal received over the entire frequency band. With the invention, the interfering band is suppressed at the same time as it is located by the band filter itself. The invention thus makes it possible to solve the technical problem of isolating and suppressing an interfering signal of a radio signal received by a very broadband receiver Whatever the position of the interfering band in the operating frequency band of the receiver . According to one aspect of the invention, the reference energy level used by the comparing step is that of the received radio signal and the selected filtering frequency corresponding to the highest energy variation is identified as the central frequency. of the interfering frequency band. Since the energy of the interfering signal is much greater than that of the wanted signal, the better the band filter is centered on the interfering band, the greater the variation (decrease) in energy between the filtered signal and the original radio signal received. According to one aspect of the invention, the reference energy level used by the comparing step is initialized to the value of the energy level calculated for a selected filtering frequency and in that the selected filtering frequency corresponding to the The lowest energy level obtained is identified as the center frequency of the interfering frequency band.

At initialization, the reference energy level is taken at random. The lowest level of residual energy is sought. An advantage of this solution is that it is simple to implement. According to one aspect of the invention, the locating phase further comprises a step of controlling frequency translation of the received radio signal to center it on the selected filtering frequency. The received radio signal is varied rather than the band filter, allowing only one static band filter to be used for a desired bandwidth. According to another aspect of the invention, the detection method further comprises a location refinement phase, during which steps 1) to 3) are implemented in a subband centered on the identified central frequency, said first center frequency, 20 with a second band filter width at least equal to the first width and using a second pitch less than the first step and lead to the identification of a second central frequency. In the sub-band selected by the first iteration, the second iteration scans the determined frequencies, with a lower pitch. A new center frequency is identified. This makes it possible to refine the first location of the central frequency of the interfering band brought by the first iteration. According to yet another aspect of the invention, the second step is half the width of the band filter. The pitch is chosen equal to half the width of the band filter used. This makes it possible to achieve a good complexity-quality compromise, which ensures locating the center frequency of the band filter with sufficient accuracy.

According to yet another aspect of the invention, the localization and location refinement phases in the subband centered on the identified second central frequency are implemented iteratively, as long as the minimum residual energy criterion is satisfied. , with at each iteration, a band filter of width less than that used in the previous iteration and the method comprises a step of determining a width of the interfering frequency band equal to that of the band filter used in the penultimate iteration.

The additional step is to determine the width of the interfering band by successively applying band filters of smaller and smaller widths to the subband selected in the previous step or steps. As long as the maximum residual energy variation obtained is at least equal to that calculated in the previous iteration, it is considered that the band filter has a width sufficient to remove most of the interfering band. An advantage of this aspect of the invention is to more accurately determine the width of the interfering band. Thus, the band filter will only remove the portion of the received signal corresponding to the interfering signal.

Advantageously, the width of the filter at the current iteration is chosen half width compared to that of the previous iteration. This makes it possible to converge quickly towards the width of the interfering band without multiplying the number of necessary iterations excessively.

The invention also relates to a device for detecting an interfering frequency band in a radio signal received by a very broadband receiver. Such a device is able to implement the detection method according to the invention, in its various embodiments. According to a particular embodiment, the device comprises frequency translation control means of the received radio signal to center it on the selected filtering frequency.

The invention also relates to a non-coherent energy detector capable of detecting a radio signal with a very wide frequency band, characterized in that it comprises a device for detecting an interfering frequency band according to the invention and a band filter adapted to be controlled by said device. According to one aspect of the invention, said detector further comprises a local oscillator adapted to transpose a part of the radio signal on an intermediate frequency calculated by said detection device according to the invention and a mixer able to mix the radio signal with the part transposed from said signal, the mixed signal being presented to the band filter. One advantage is that a fixed central frequency band filter can be used to scan the entire frequency band of the received radio signal. The invention also relates to a receiver of a radio signal with a very broad frequency band, comprising a non-coherent energy detector according to the invention. The invention finally relates to a computer program comprising instructions for implementing the detection method as described above, when this program is executed by a processor. Such a program can use any programming language. It can be downloaded from a communication network and / or saved on a computer-readable medium.

3. List of Fibers Other advantages and features of the invention will appear more clearly on reading the following description of a particular embodiment of the invention, given as a simple illustrative and non-limiting example, and attached drawings, among which: Figure 1 shows schematically the principle of a receiver comprising a non-coherent energy detector according to the prior art; FIG. 2 shows an exemplary power spectrum of an ultra wideband signal received by a receiver; FIG. 3 shows the steps of the method for detecting an interfering frequency band for an ultra wide band radio signal according to a first embodiment of the invention; Figure 4 schematically shows the principle of transposition of frequencies according to one aspect of the invention; FIG. 5 shows the steps of the method for detecting an interfering frequency band for an ultra wideband radio signal according to a second embodiment of the invention; Fig. 6 schematically illustrates the loss of useful energy on the received radio signal caused by the application of a bandwidth filter too wide; FIG. 7 shows the steps of the method for detecting an interfering frequency band for an ultra wideband radio signal according to a third embodiment of the invention; Figure 8 shows schematically an exemplary structure of a radio receiver comprising a non-coherent energy detector according to one embodiment of the invention.

4. DESCRIPTION OF A PARTICULAR EMBODIMENT OF THE INVENTION The general principle of the invention rests on the scanning of the frequency band of an ultra wideband signal received by a receiver, for the purpose of application, a band filter centered on certain frequencies of the scanned band and by the selection of the frequency corresponding to the radio signal satisfying at best a minimum residual energy criterion. The invention is based on the fact that, in a radio signal, the useful part of this signal, such as white noise, has a mean level of constant energy over the entire frequency band, whereas the interfering signal is contrary a peak of high energy on a subband of frequencies, called interfering band. In the remainder of the description, a radio signal is considered capable of comprising at least the following three components: white noise; a useful radio signal transmitted, for example by means of the UWB technology, according to which a symbol time is divided into Nf frames of length Tf, with Nf integer greater than or equal to 1, Tf being a duration expressed in units of time, a frame being divided into Nc "chips" of length Tc, with Nc integer greater than or equal to 1, Tc being a duration expressed in units of time, such that TS = Nf * Tf = Nc * Tc. The UWB radio signal is modulated using one of the modulation techniques usually implemented for UWB technology, such as PPM ("Pulse Position Modulation"), O0K ("On-Off Keying", in English), BPSK ("Binary Phase shift keying", in English), PPM-BPSK etc. It is then processed by a receiver as shown in connection with Figure 1; an interfering signal due to the simultaneous transmission of a narrow-band signal in the frequency band of the wanted radio signal expected by the receiver. The invention is therefore not limited to the reception of a UWB signal, but it potentially applies to any radio signal whose bandwidth is significantly greater than the band of the interfering signal, said narrow-band interfering signal. that is, with at least a ratio of 4 between the width of the signal bandwidth and that of the interfering band, whether or not this radio signal includes a useful radio signal or is limited to white noise. Indeed, the interfering signal is always present whether or not the wanted signal is transmitted to the broadband receiver.

In connection with FIG. 2, an exemplary power spectrum of an ultra wideband radio signal received by a UWB receiver is considered. There is a very sharp power peak around the 3.5 GHz frequency. This peak corresponds to an interfering signal that has mixed with the ultra wideband radio signal. It is understood that its energy level, much higher than that of the ultra wideband radio signal, makes it localizable in the power spectrum of the received radio signal.

The steps of the method for detecting an interfering frequency band FBI according to a first embodiment of the invention are now presented in relation to FIG.

In El, a plurality of filter frequencies fi to fN, N are selected in the frequency band of the received signal, two successive frequencies being spaced apart by a predetermined pitch. The selected frequencies are then successively processed in the following manner: For n ranging from 1 to N: In E3, a band FB filter of width B centered on the determined frequency fn is applied. In E4, the residual energy level ERn of the filtered radio signal is calculated and compared at E5 to the levels calculated for the above frequencies fi to fn-1. If the current residual energy level is lower than the previous ones, it is stored in memory, as well as its associated central frequency fn. According to one variant, it is also possible to compare the energy level of the filtered signal with that of the original signal, to compare the variation obtained with that resulting from the processing of the preceding frequencies, and to store this new variation if it is stronger than that stored. in memory. The index n is incremented. Steps E2 and E3 are repeated for the following frequencies. The process stops when all the frequencies determined in El have been processed. In a step E6, the central frequency stored in memory is selected, as the best estimate fci of the center frequency of a frequency sub-band SBi of width B comprising at least a large part of the interfering frequency band FBI. By way of example, if we consider a bandwidth UWB of width W = 500 MHz, the bandwidth B of the filter is advantageously chosen equal to 50 MHz. The number of filtering frequencies selected is therefore N = W / B = 10. It corresponds to the number of iterations of the filtering step using the FB band filter. This makes it possible to achieve a good complexity-quality compromise, the cost of the filtering process remaining reasonable. As mentioned above, a symbol is formed of at least one pulse. It usually includes several, between two and several thousand depending on the type of signal considered.

A symbol time corresponds to the time required for an energy detector to detect a symbol. The duration of an iteration of the detection method according to the invention is limited by the time required to measure the energy of the filtered signal during the first time. 'étapeE4. Two cases are possible. In a first case, the detection and the integration of the energy are made for a pulse of the filtered signal. This requires that the signal pulses provide enough energy. According to a second case, the energy detection is done for each pulse, but it is integrated on all the pulses composing the symbol. The energy level detected for each pulse is therefore integrated over the duration of the symbol. This second case is more suited to pulses with a low energy level. In the example considered of a band of 500 MHz and a filter FB of bandwidth B = 50 MHz, two symbol times will be sufficient to execute the scanning process of the band of frequencies according to the first case, whereas the second case will require at least 20 symbols to scan the entire band, regardless of the number of pulses per symbol.

According to one aspect of the invention, the detection method comprises a step E2 of transposition of the received radio signal of the selected frequency fn on an intermediate frequency fi so that the part of the radio signal centered on the frequency fn is superimposed to the FB band filter centered on the frequency fB. This additional step makes it possible to use a fixed band filter, thus inexpensive, for all the determined frequencies of the frequency band of the radio signal received. In relation to FIG. 4, the principle of the transposition of the radio signal and the filtering of the signal transposed by an FB band filter is schematically presented. We consider a fixed band filter, centered on its frequency fB, while the current fn filtering frequency of the radio signal is transposed on an intermediate frequency fi calculated as follows: We consider the current iteration n, with n integer understood between 1 and N and df the difference between the determined frequency fn of the received signal and the center frequency fB of the band filter. The intermediate frequency est is calculated as follows; fi = fB + (N / 2-n) B = fn-df + (N / 2-n) B Note that the transposition process is necessarily limited by a lower bound defined by the following relation: wi = fi -W / 2 with wi> O. In other words, the calculated intermediate frequency est is necessarily greater than W / 2. The implementation of the detection method according to the invention which has just been described makes it possible to obtain a coarse localization of the FBI interfering frequency band.

In relation to FIG. 5, an example embodiment of the detection method according to a second embodiment of the invention is now presented. In this example, the steps E1 to E6 that have just been described are implemented, as in the previous example, in a first phase Phi, leading to the location of a sub-band of frequencies SBi of width Bi and centered on the selected frequency fci. According to this second embodiment of the invention, the detection method according to the invention comprises a second phase Ph2, called localization refinement, which applies to the sub-band SB1 centered on the selected frequency fci and of width Bi [fo.- Bi / 2, fci + Bi / 2]. This second phase Ph2 again implements the steps E1 to E6, say E'1 to E'6, this time as follows:

Consider a second pitch P2, lower than the first pitch Pi. For example, P2 is equal to half of Pi.

According to a step E'1, M is selected filtering frequencies f'm, M integer greater than or equal to 1, in the sub-band SBi, two successive frequencies being distant from the second pitch P2 so that M = Bi / P2 . The selected filter frequencies are then successively processed, as follows: For n ranging from 1 to M: In E'2, a part of the signal of the current frequency f'm is transposed to the intermediate frequency f'i, calculated as in the previous phase P1. In E'3, the band FBi filter of width Bi centered on the filtering frequency f'i is applied. In E'4, the residual energy level of the filtered radio signal is calculated and is compared in E'5 with the levels calculated for the preceding frequencies f'i to f'm-i. In E'5, if the current residual energy level is lower than the previous ones, it is stored in memory, for example in a database BDD, and its associated frequency f'm. The index m is incremented. Steps E'2 and E'6 are repeated for the following determined frequencies f'm.

The process stops when all the frequencies determined in E'1 have been processed. In a final step E'6, the filtering frequency stored in memory is selected, as a second estimate of the center frequency fc2 of a sub-band SB2 of frequencies of width Bi comprising at least a large part of the interfering frequency band FBI.

Using a finer pitch and the same band filter, the first estimate fci of the center frequency of the interfering frequency band was refined.

In connection with FIGS. 6a and 6b, two examples of power spectra of a radio signal filtered with two band filters of different widths are presented.

In the example of FIG. 6a, the applied band filter has a width Bi much greater than that of the desired interfering frequency band, which leads to a loss of a non-negligible portion of the useful radio signal. In the example of FIG. 6b, on the contrary, the applied band filter is narrower and better adapted to the width of the interfering frequency band, which makes it possible to limit the loss of useful radio signal due to band filtering. It is understood from these two examples that it is important to choose a bandwidth filter as close as possible to the interfering frequency band FBI.

In relation to FIG. 7, an example embodiment of the detection method according to a third embodiment of the invention is presented. In this example, the phase Phi of coarse localization of a central frequency of the interference frequency band, is not only followed by a phase Ph2 of refinement of location according to the steps E'1 to E'5, but also of a Determination phase Phi of the width of the interfering frequency band. This last phase will now be described in more detail: It applies to the sub-band SB2 centered on the second central frequency fc2 determined at the end of the second phase Ph2, and of width Bi equal to that of the band filter used during phases Phi and Ph2. During this third phase, the steps E1 to E6 and E'1 to E'6 are successively implemented, iteratively, with each iteration a band filter of width less than that of the previous iteration. We consider, at the initialization of this third phase, an index i initialized to 1, a broadband filter B3, i equal to Bi / 2 and a pitch P3 equal to B3, for the steps E1 to E6, then equal at half B3, i / 2 for steps E'1 to E'6.

The process is iterated as long as the minimum residual energy criterion is satisfied, which ensures that the band filter has a width sufficient to remove the bulk of the interfering signal. The reference energy level is initialized with the residual energy level ER calculated in the previous phase Ph2. According to the method used to evaluate the satisfaction of this criterion, it will be a question respectively of ensuring that the residual energy level calculated at the current iteration is lower than that stored for the previous iteration or of verifying that the variation of energy between the original radio signal and the filtered radio signal is maximum. For example, at the end of steps E'1 to E'6, the residual energy level ER corresponding to the best estimate of the center frequency fc2, i of the interfering frequency band is compared with that stored at from the refinement phase of the localization for the estimated frequency fc2, ii. If the current residual energy level is less than or equal to the level stored in the database BDD, the process is iterated again with a bandwidth filter half B3, i + i = B3, i / 2, otherwise the process stops. In the latter case, it is the width B3, i-i of the filter of the previous iteration i-1 which is considered, in a step E'7, as the best estimate of the width of the interfering frequency band BBFI. Indeed, a rising level of residual energy means that the band filter no longer has a width sufficient to cover the entire interfering frequency band. This additional phase makes it possible to choose the bandwidth filter most adapted to the interfering frequency band present in the received radio signal. It should be noted that in fact, the use of a narrower band filter, by reducing the uncertainty on the central frequency of the interfering band, makes it possible at the same time to refine the estimate of the position of this frequency.

The method for detecting an interfering frequency band that has just been described in its various embodiments may advantageously be implemented by a detection device 100 according to the invention. According to one embodiment of the invention, presented in connection with FIG. 8, such a device is integrated with a receiver 1 comprising a non-coherent energy detector 10 associated with an antenna A.

The receiver 1 comprises, in a conventional manner, in addition to the antenna A, amplification means 11, such as an LNA amplifier and band-pass filtering means 12, implementing a filter of the BPF type. These various means constitute what is generally called the RF front-end stage of the receiver and make it possible in particular to provide an SRT-processed radio signal in a manner adapted to the detector 10.

The noncoherent energy detector 10 according to the invention comprises band filtering means 15, means 16 for detecting a quadratic energy level of a pulse or a symbol of the received radio signal, means integration 17 of the energy level detected on the frequency band and symbol decision means 18 able to decide whether the detected radio signal portion SD comprises the zero or one symbol. The detector 10 according to the invention further comprises a local oscillator 13 adapted to transpose a portion of the detected radio signal SD on a predetermined intermediate frequency fi and a mixer 14 able to mix the processed radio signal with the transposed part of the radio signal in order to its filtering by the band filtering means 15.

It should be noted that, according to the invention, the band filter 15 occupies a much more downward position in the ultra wideband radio signal processing chain and forms an integral part of the noncoherent energy detector 10.

The detector 10 further comprises the detection device 100 according to the invention. In the embodiment described here, the hardware architecture of the detection device 100 includes the elements found in a conventional computer. The device 100 comprises in particular a processor 110, a random access memory RAM 120 and a ROM ROM 130 comprising a number of applications that can be executed by the process 11 in cooperation with the random access memory 120. Read-only memory ROM type 130 is a recording medium according to the invention. This recording medium comprises a computer program PG comprising instructions for allowing the processor 110 to execute the steps of the method for detecting an interfering frequency band according to the invention which has just been described with reference to the preceding figures. It also allows the storage of residual energy levels and intermediate central frequencies calculated by the detection method according to the invention, for example in a database BDD. Thus, the processor 110, by implementing the computer program PG, is able to: a) select a plurality of filter frequencies in the frequency band of the radio signal, two by two distant by a predetermined pitch; b) for each selected frequency, - controlling the filtering of a radio signal using a band filter of predetermined width, at least equal to said pitch and centered on the selected filtering frequency; - obtain a level of energy of the filtered signal; - comparing the energy level obtained with a reference energy level; c) detecting the center frequency of the interfering frequency band among the selected filtering frequencies, according to said comparison, according to a minimum residual energy criterion. The device according to the invention, by suppressing the interfering signal, thus allows the energy detector to effectively detect the symbols carried by the useful radio signal. Of course, other embodiments of the invention may be envisaged. It will be noted in particular that the detection method which has just been described may be implemented both during a synchronization phase and during a phase of transmission of useful data. It can also be executed when no useful data pulse is transmitted. Indeed, the interfering frequency band is always present, even when the radio signal is reduced to white noise. Since the white noise has the same constant energy property over the entire frequency band as the wanted signal, the detection method according to the invention applies in the same way. Once the receiver knows the frequency spectrum occupied by the pulses already transmitted, it can scan the entire spectrum, although the expected signal has not yet been sent. This case can be very practical to achieve energy savings and to detect interfering frequency bands of low power, not exceeding that of the useful signal and which are therefore difficult to detect.

Claims (14)

  1. REVENDICATIONS1. A method for detecting an interfering frequency band for a radio signal received by a receiver (1) with a very wide frequency band, characterized in that it comprises a phase of localization (Phi) of said interfering frequency band comprising the next steps: - 1) Selection (El) of a plurality of filter frequencies in the frequency band of the radio signal, two by two distant by a predetermined pitch;
  2. 2) for each selected filtering frequency, filtering control (E3) of the radio signal using a band filter of predetermined width, at least equal to said pitch and centered on said filtering frequency; obtaining (E4) an energy level of the filtered radio signal; comparing (E5) the energy level obtained at a reference energy level;
  3. 3) identifying (E6) a central frequency (fco) of the interfering frequency band among the selected filtering frequencies, according to said comparison, according to a minimum residual energy criterion. 2. A method of detecting an interfering frequency band according to claim 1, characterized in that the reference energy level used by the comparison step (E5) is that of the received radio signal and that the frequency The selected filtering frequency corresponding to the highest energy variation is identified as the center frequency of the interfering frequency band. 3. A method for detecting an interfering frequency band according to claim 1, characterized in that the reference energy level used by the comparison step (E5) is initialized to the value of the energy level calculated for a selected filtering frequency and that the selected filtering frequency corresponding to the lowest energy level obtained is identified as the center frequency of the interfering frequency band.
  4. 4. A method of detecting an interfering frequency band according to claim 1, characterized in that the locating phase further comprises a control step (E2) of frequency transposition of the received radio signal to center it on the frequency. selected filter.
  5. 5. A method for detecting an interfering frequency band according to claim 1, characterized in that it further comprises a phase (Phz) of refinement of location, during which steps 1) to 3) are set in a sub-band (SBI) centered on the identified central frequency (fci), said first central frequency, with a second band filter width (B2) at least equal to the first width and using a second step (P2) less than the first step (Pi) and lead to the identification of a second central frequency (fc2).
  6. 6. A method of detecting an interfering frequency band according to claim 5, characterized in that the second pitch (P2) is half the width of the band filter.
  7. 7. A method for detecting an interfering frequency band according to claim 5, characterized in that the localization (Phi) and localization refinement (Ph2) phases are implemented iteratively in the centered subband. on the identified second center frequency (fc2), as long as the minimum residual energy criterion is satisfied, with at each iteration a band filter of a width smaller than that used in the previous iteration and and that the method comprises a step of determining (E'7) a width (B3) of the interfering frequency band equal to that of the band filter used in the penultimate iteration (i-1).
  8. 8. A method of detecting an interfering frequency band according to claim 7, characterized in that the width of the filter at the current iteration is chosen half width relative to that of the previous iteration.
  9. 9. Device for detecting (100) an interfering frequency band for a radio signal received by a receiver (1) with a very wide frequency band, characterized in that it comprises means for locating said frequency band interfering means comprising: 1) sub-means for selecting a plurality of filter frequencies in the frequency band of the radio signal, two by two distant by a predetermined pitch; 2) sub-means, adapted to be implemented for each selected filtering frequency, for controlling the filtering of the radio signal using a band filter of predetermined width, at least equal to said pitch and centered on said filtering frequency; obtaining an energy level of the filtered radio signal; comparing the energy level obtained with a reference energy level; 3) sub-means for identifying a central frequency of the interfering frequency band among the selected filtering frequencies, according to said comparison, according to a minimum residual energy criterion.
  10. 10. A device (100) for detecting an interfering frequency band for a radio signal received by a very broadband receiver according to claim 9, characterized in that it further comprises transposition control means. in frequencies of the received radio signal to center it on the selected filtering frequency.
  11. 11. Non-coherent energy detector (10) capable of detecting a radio signal with a very wide frequency band, characterized in that it comprises a device (100) for detecting an interfering frequency band according to FIG. claim 9 and a band filter (FB) adapted to be controlled by said device.
  12. 12. non-coherent energy detector (10) according to claim 11, characterized in that it further comprises a local oscillator (14) adapted to transpose a portion of the radio signal on an intermediate frequency (fi) calculated by said device detection device (100) and a mixer (13) adapted to mix the radio signal with the transposed part of said signal, the mixed signal being presented to the band filter (FB).
  13. 13. Receiver (1) of a very broadband radio signal, characterized in that it comprises a non-coherent energy detector (10) according to claim 11 or 12.
  14. 14. Computer program (PG) characterized in that it comprises instructions for the implementation of a detection method according to claim 1, when the program is executed by a processor. 20
FR1152752A 2011-03-31 2011-03-31 Method for detecting an interference frequency band in a very broadband frequency radio signal, device and receiver therefor Pending FR2973613A1 (en)

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FR1152752A FR2973613A1 (en) 2011-03-31 2011-03-31 Method for detecting an interference frequency band in a very broadband frequency radio signal, device and receiver therefor
PCT/FR2012/050638 WO2012131248A1 (en) 2011-03-31 2012-03-27 Method for detecting a band of interfering frequencies in a radio signal having a very wide frequency band, and related device and receiver

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Citations (2)

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WO2001078242A2 (en) * 1999-04-28 2001-10-18 Isco International, Inc. Interference detection, identification, extraction and reporting
EP2056486A2 (en) * 2007-10-30 2009-05-06 Broadcom Corporation Method and system for detecting bluetooth signals utilizing a wideband receiver

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001078242A2 (en) * 1999-04-28 2001-10-18 Isco International, Inc. Interference detection, identification, extraction and reporting
EP2056486A2 (en) * 2007-10-30 2009-05-06 Broadcom Corporation Method and system for detecting bluetooth signals utilizing a wideband receiver

Non-Patent Citations (1)

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Title
ABDAOUI R ET AL: "Performances analysis dedicated to 60 GHz multiband impulse transceiver for Gbits data rate short range communication systems", WIRELESS TECHNOLOGY CONFERENCE (EUWIT), 2010 EUROPEAN, IEEE, PISCATAWAY, NJ, USA, 27 septembre 2010 (2010-09-27), pages 41-44, XP031784748, ISBN: 978-1-4244-7233-8 *

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