• 专利附录
  • 专利说明
  • 权利要求
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    • 专利摘要:
    The present invention relates to a method (50) for transmitting a broadcast signal by an access network (30) to a plurality of terminals (20) of a bidirectional wireless communication system, said method comprising: - forming (51) an information signal SI1 from broadcast information to said terminals (20), - forming (52) a pilot signal SP, - transmitting (53) ) a broadcast signal comprising the information signal SI1 and the pilot signal SP, said information signal SI1 and said pilot signal SP being transmitted on different respective central frequencies having a predetermined frequency deviation ΔF1. The invention also relates to a method (60) adapted for receiving a broadcast signal.
    公开号:FR3036907A1
    申请号:FR1554890
    申请日:2015-05-29
    公开日:2016-12-02
    发明作者:Christophe Fourtet；Lionel Zirphile
    申请人:Sigfox SA；
    IPC主号:
    专利说明:

    [0001] TECHNICAL FIELD The present invention belongs to the field of wireless communication systems, and more particularly relates to a method for transmitting broadcast signals by a group of base stations of an access network intended for terminals, as well as a method of receiving said broadcast signals. STATE OF THE ART The present invention finds a particularly advantageous, though in no way limiting, application in ultra-narrowband wireless communication systems. "Ultra-narrow band" ("Ultra Narrow Band" or UNB in the English literature) means that the instantaneous frequency spectrum of the radio signals emitted by the terminals, to the access network, is of lower frequency width to one kilohertz.
    [0002] Such UNB wireless communication systems are particularly suitable for applications of the type M2M (acronym for machine-to-machine) or the Internet of Things ("Internet of Things" or loT in the literature Anglo-Saxon). In such a UNB wireless communication system, the data exchanges are essentially monodirectional, in this case on a rising link between terminals and an access network of said system. The terminals transmit uplink messages that are collected by base stations of the access network, without having to first associate with one or more base stations of the access network. In other words, the upstream messages sent by a terminal are not intended for a specific base station of the access network, and the terminal transmits its upstream messages assuming that they can be received by at least one forwarding station. based. Such provisions are advantageous in that the terminal does not need to make regular measurements, particularly greedy in terms of power consumption, to determine the most appropriate base station to receive its upstream messages. The complexity lies in the access network, which must be able to receive uplink messages that can be transmitted at arbitrary times and on arbitrary central frequencies.
    [0003] 3036907 2 Each base station of the access network receives upstream messages from the different terminals that are within its reach. Such a mode of operation, in which the data exchanges are essentially monodirectional, is quite satisfactory for many applications, such as, for example, remote reading of gas meters, water meters, electricity meters, telemonitoring of buildings or houses, etc. In some applications, however, it may be advantageous to also be able to perform data exchanges in the other direction, namely on a downlink from the access network to the terminals.
    [0004] In particular, it may be advantageous to transmit broadcast signals, global or group (respectively "broadcast" or "multicast" in the Anglo-Saxon literature), to the terminals. In particular, several frequency bands may be possible for the transmission of the upstream messages, for example respectively associated with different geographical regions which may be subject to different regulatory constraints. The emission of broadcast signals could then enable the terminals to identify the frequency band of the uplink link in the geographic region in which they are located, and before sending up messages in a frequency band not provided for this purpose. For example, it would be possible to transmit the broadcast signals in the frequency band of the uplink or in a frequency band having a predefined frequency deviation from the frequency band of the uplink. Such broadcast signals could also be implemented to transmit any type of information that may be useful for all terminals, or for a large number of them. However, to limit the manufacturing cost of the terminals, the reception of the broadcast signals must be able to be carried out simply and economically. In particular, it is desirable that the reception of the broadcast signals can be carried out by terminals equipped with poorly performing frequency synthesis means. DISCLOSURE OF THE INVENTION The present invention aims to remedy all or part of the limitations of the solutions of the prior art, in particular those set out above, by proposing a solution that makes it possible to limit the complexity of the reception of broadcast signals. For this purpose, and according to a first aspect, the invention relates to a method for transmitting a broadcast signal by an access network to a plurality of terminals of a bidirectional wireless communication system, said transmission method comprising: - forming an information signal S11 from broadcast information to said terminals, - forming a pilot signal SP, - transmitting a signal of broadcast comprising the information signal S11 and the pilot signal SP, said information signal S11 and said pilot signal SP being transmitted on different respective central frequencies having a predetermined frequency deviation AF1.
    [0005] Thus, according to the invention, the broadcast signal comprises an information signal S11 and a pilot signal SP, transmitted with frequency deviation AF1 predetermined with respect to said information signal S11, known a priori by the terminals that wish to extract the data. broadcast information included in said information signal S11. This predetermined frequency difference AF1 forms a characteristic signature of said broadcast signal, which can be detected in a simple manner by these terminals. In particular, a non-linear filtering of the broadcast signal will form several replicas of the information signal S11 and of the pilot signal SP, on frequencies which depend on the central frequencies on which said information signal S11 and said pilot signal SP have been issued. In particular, a non-linear filtering comprising a quadratic effect will form a replica of the information signal S11 on the frequency AF1. The accuracy of the center frequency AF1 of the information signal S11 depends mainly on the accuracy of synthesis of the central transmission frequencies at the access network. In addition, because the central frequency AF1 can be chosen much lower than the central transmission frequencies, said central frequency AF1 can also be synthesized with good accuracy by the terminals, including with poorly performing frequency synthesis means 3036907 4 . In particular modes of implementation, the transmission method may further comprise one or more of the following characteristics, taken separately or in any technically possible combination.
    [0006] In particular embodiments, the broadcast signal transmission method comprises the formation of another information signal S12, said information signal S12 being transmitted on a central frequency having a predetermined frequency difference AF2. relative to the center frequency of the pilot signal SP, the frequency difference AF2 being different from the frequency difference AF1. In particular modes of implementation, the information signal S12 is formed from the same broadcast information as that of the information signal S11. In particular modes of implementation, the information signal S12 is formed from information of diffusion distinct from that of the information signal S11. In particular embodiments, the information signal S11 and the information signal S12 are formed according to different respective physical layer protocols.
    [0007] In particular embodiments, the information signal S11 and the information signal S12 are formed according to different modulations. In particular embodiments, the respective central frequencies of the pilot signal SP and of each information signal 25 vary over time, the frequency difference, between the central frequency of the pilot signal SP and the central frequency of each information signal, being constant over time. In particular modes of implementation, the pilot signal SP is a sinusoidal signal.
    [0008] In particular embodiments, the frequency difference AF1 is less than 10 kilohertz, preferably less than 1 kilohertz. In particular modes of implementation, the information signal S11 is ultra-narrow band.
    [0009] In particular modes of implementation, the information signal SI1 has a spectral width less than twice the frequency difference AF1. According to a second aspect, the present invention relates to a base station comprising means configured to implement a broadcast signal transmission method according to any of the embodiments of the invention. According to a third aspect, the present invention relates to an access network comprising means configured to implement a broadcast signal transmission method according to any one of the embodiments of the invention. According to a fourth aspect, the present invention relates to a method of reception, by a terminal, of a broadcast signal transmitted according to a transmission method according to any of the embodiments of the invention, said method receiver comprising: - the non-linear filtering of a signal received by the terminal, - the search for a broadcast signal from a signal obtained, after non-linear filtering of the received signal, on the frequency AF1, a diffusion signal being detected when said signal obtained on the frequency AF1 satisfies a predefined detection criterion.
    [0010] In particular embodiments, the receiving method may further comprise one or more of the following features, taken alone or in any technically possible combination. In particular embodiments, the reception method comprises extracting the broadcast information of the detected broadcast signal from the signal obtained, after non-linear filtering, on the frequency AF1. In particular embodiments, the non-linear filtering includes amplifying the received signal by means of a saturated amplifier or the envelope detection of the received signal by means of an envelope detector circuit. In particular modes of implementation, the extraction of the broadcast information comprises the open-loop generation of a sinusoidal signal of frequency AF1, and the multiplication of the signal obtained after non-linear filtering by said sinusoidal signal of frequency AF1. . According to a fifth aspect, the present invention relates to a terminal having means configured to implement a broadcast signal receiving method according to any one of the embodiments of the invention. PRESENTATION OF THE FIGURES The invention will be better understood on reading the following description, given by way of non-limiting example, and with reference to FIGS. 10 which represent: FIG. 1: a schematic representation of a communication system FIG. 2 is a diagram illustrating the main steps of a method for transmitting a broadcast signal. FIG. 3 is a schematic representation, in the frequency domain, of an example of a broadcast signal transmitted. according to the transmission method of FIG. 2; FIG. 4: a diagram illustrating the main steps of an implementation variant of the transmission method of FIG. 2; FIG. 5: a diagrammatic representation in FIG. frequency domain, an example of a broadcast signal transmitted according to the transmission method of FIG. 4; FIG. 6: a diagram illustrating the main steps of a method of reception of a broadcast signal.
    [0011] In these figures, identical references from one figure to another designate identical or similar elements. For the sake of clarity, the elements shown are not to scale unless otherwise stated. DETAILED DESCRIPTION OF EMBODIMENTS FIG. 1 schematically represents a wireless communication system 10, for example of the UNB type, comprising several terminals 20 and an access network 30 comprising several base stations 31. The terminals 20 and the stations the base station 31 of the access network 30 36907 7 exchange data in the form of radio signals. By "radio signal" is meant an electromagnetic wave propagating via non-wired means, the frequencies of which are included in the traditional spectrum of radio waves (a few hertz to several hundred gigahertz). The terminals 20 are adapted to transmit uplink messages on a uplink link to the access network 30. Each base station 31 is adapted to receive the uplink messages of the terminals 20 which are within range. Each received message 10 is for example transmitted to a server 32 of the access network 30, possibly accompanied by other information such as an identifier of the base station 31 which received it, the measured power of said received message amount, the received date and / or the measured center frequency of said received amount message, etc. The server 32 processes, for example, all the received messages received from the different base stations 31. In this case, the wireless communication system UNB is bidirectional, and the access network 30 is also adapted to transmit, via the base stations 31, downlink broadcast signals to terminals 20 which are adapted to receive them. The broadcast signals may be broadcast signals in the English literature and / or group broadcast signals ("multicast" in the Anglo-Saxon literature). Such broadcast signals comprise digital information, called "broadcast information", intended for all or some of the terminals 20. The broadcast information may be any type of information that may be useful for all the terminals 20, or for a group of terminals 20. For example, the broadcast information is intended to control the operation of the terminals 20, for example for the transmission of upstream messages on the upstream link. In particular, if several frequency bands are possible for the transmission of the uplink messages, then the broadcast signals may comprise control information enabling the terminals to identify the frequency band in which they must transmit their uplink messages. According to another nonlimiting example, it is also possible to issue a control information enabling the different terminals to be synchronized temporally with each other, for example a control information item corresponding to the time in UTC Coordinated Universal Time Scale. The broadcast signals transmitted by the base stations 31 are, for example, of limited duration, for example between a few hundred milliseconds and a few seconds. If necessary, the emission of the broadcast signal is discontinuous, and a base station 31 for example transmits a broadcast signal recurrently, the broadcast information may vary from one program to another. However, there is nothing to preclude, according to other examples, having a broadcast signal transmitted continuously by a base station 31. The present invention relates in particular to a method 50 for transmitting a broadcast signal by the access network 30, and a method 60 for receiving a broadcast signal by a terminal 20.
    [0012] A) Diffusion signal transmission method FIG. 2 schematically illustrates the main steps of a method for transmitting a broadcast signal by the access network 30. As illustrated by FIG. the transmission method 50 mainly comprises the following steps, which will be described in more detail below: - 51 formation of an information signal SI1 from broadcast information to a plurality of terminals 20 - 52 formation of a pilot signal SP, - 53 transmission of a broadcast signal comprising the information signal SI1 and the pilot signal SP, said information signal SI1 25 and said pilot signal SP being transmitted on frequencies respective different plants having a predetermined frequency difference AF1. Of the various steps illustrated in FIG. 2, only the broadcast signal transmitting step 53 must necessarily be at least partially executed by a base station 31. The other steps illustrated in FIG. 2 can be executed by a base station 31 and / or by the server 32 of the access network 30. For example, the step 51 of forming the information signal SI1 and the step 52 of forming the pilot signal SP can be performed by the server 32, which then transmits the information signal SI1 and the pilot signal SP to a base station 31 which transmits the broadcast signal during the transmission step 53. In the remainder of the description, it is placed in the case where the steps 5 illustrated in FIG. 2 are all executed by the base stations 31 of said access network 30. It should however be noted that the broadcast information, at from which a base station 31 forms the information signal S11, may nevertheless be provided by the server 32. The base stations 31 comprise, for example, respective processing modules (not shown in the figures), each processing module for example comprising one or more processors and storage means (magnetic hard disk, electronic memory, optical disk, etc.) in which is stored a computer program product, in the form of a set of code instructions of program to be performed to implement the various steps of the broadcast signal transmission method 50. In a variant, each processing module comprises one or more programmable logic circuits, of the FPGA, PLD, etc. type, and / or specialized integrated circuits (ASIC) adapted to implement all or part of said steps of the transmission method 50. broadcast signal.
    [0013] Each base station 31 further comprises wireless communication means, known to those skilled in the art, enabling said base station to receive upstream messages and to transmit broadcast signals in the form of radio signals. In other words, the base stations 31 of the access network 30 comprise respective means configured in software (specific computer program product) and / or hardware (FPGA, PLD, ASIC, etc.) to put implement the different steps of the broadcast signal transmission method 50. The information signal SI1 is formed from the broadcast information during the forming step 51 in a conventional manner. For example, the broadcast information may be encoded by error correction code, and control information may be added, such as a time synchronization pattern, error detection data (by example a cyclic redundancy check - "Cyclic Redundancy Check" or CRC in the English literature), an identifier of a group of terminals 20 in the case of a multicast, and so on. The data thus obtained can then be modulated according to any method known to those skilled in the art, for example according to a BPSK modulation ("Binary Phase Shift Keying", GFSK (Gaussian Phase Shift Keying), etc. The signal The pilot SP is intended to be transmitted, in the broadcast signal, with a predetermined non-zero frequency difference AF1 with respect to the information signal S11.This frequency difference AF1, which is known a priori from the terminals 20, forms a characteristic signature. of said broadcast signal, and the main function of the pilot signal SP is to realize the frequency deviation AF1 in the broadcast signal, therefore, the pilot signal SP can be particularly simple and takes the form, in preferred modes of setting. of a sinusoidal signal ("Continuous Wave" or CW in the Anglo-Saxon literature), but there is nothing to exclude, according to other examples, having a more complex SP pilot signal. According to other examples, the pilot signal SP may be formed solely from known prior data of the terminals 20, or it may be formed from a part of the broadcast information intended for the terminals 20. In the following the description is placed in a nonlimiting manner in the case where the pilot signal SP is a sinusoidal signal CW. As indicated above, the information signal SI1 and the pilot signal SP are emitted, during the step 53, on respective different central frequencies having a predetermined non-zero frequency offset AF1, known a priori from the terminals 20. It should be noted that the frequency difference AF1 can be constant over time, or vary over time, since it is known a priori terminals 20. For example, the frequency difference AF1 can take successively, from one program to another, several predefined values, all known a priori terminals 20. In the following description, we place in a non-limiting manner in the case where the frequency difference AF1 is constant during time.
    [0014] FIG. 3 schematically represents, in the frequency domain, a non-limiting example of a broadcast signal in accordance with the invention. In the example illustrated in FIG. 3, the central frequency FI1 on which the information signal SI1 and the central frequency FP on which the pilot signal SP is sent (that is to say the frequency of the signal) is transmitted. sinusoidal CW) are related by the following expression: FI1 = FP + AF1 It should be noted that the center frequencies FI1 and FP are high, typically greater than several megahertz, or even greater than several hundreds of megahertz. For example, the center frequencies FI1 and FP are included in the ISM band ("Industrial, Scientific and Medical"). On the other hand, the frequency deviation AF1 is preferably much lower than the central frequencies FI1 and FP. In preferred modes of setting, the frequency deviation AF1 is less than 10 kilohertz, or even less than 1 kilohertz. Such arrangements are advantageous in that they make it possible on the one hand to limit the spectral width of the broadcast signal (and therefore the width of the frequency band in which a terminal 20 must search for the broadcast signal) and, on the other hand, to on the other hand, to allow the reception of the broadcast signal with poorly performing frequency synthesis means, as described below.
    [0015] In the example illustrated in FIG. 3, the information signal SI1 has a spectral width less than twice the frequency difference AF1. For example, the spectral width of the information signal is of the order of 100 Hertz, and the frequency difference AF1 is equal to 200 Hertz. Such arrangements facilitate the reception of the broadcast signal. Nothing, however, excludes, according to other examples, having an information signal SI1 of spectral width greater than twice the frequency deviation AF1. The central frequency FI1 of the information signal SI1 and the central frequency FP of the pilot signal SP are for example constant over time. However, in such a case, the scattering signal is not robust in the presence of interference. To improve the interference robustness, the center frequencies FP and F1 of the pilot signal SP and of the information signal SI1 vary over time in a predefined frequency band. On the other hand, the frequency deviation AF1 between the center frequency FP of the pilot signal SP and the central frequency F1 of the information signal S11 preferably remains constant over time. In other words: FI1 (t) = FP (t) + AF1 The temporal variation of the central frequencies FP and FI1 is for example continuous. According to a first example, the variation of the central frequencies FP and FI1 is sinusoidal, for example according to the following expressions: FP (t) = Fo + Ao.sin (wo.t) 10 FI1 (t) = FP (t) + AF1 expressions in which: - Fo corresponds to a predefined reference frequency, - Ao corresponds to a predefined amplitude of variation, - wo corresponds to a predefined variation pulse.
    [0016] Therefore, the center frequency FP of the pilot signal SP varies in a predefined BP frequency band having a lower bound FP1 and an upper bound FP2. In the example above, the frequency FP1 is equal to (Fo - Ao) and the frequency FP2 is equal to (Fo + Ao). It should be noted that, unlike the frequency deviation AF1, the reference frequency Fo, the amplitude of variation Ao and the variation pulse w0 are not known from the terminals 20. However, it may be advantageous to , to limit the complexity of said terminals 20, that the frequency band BP is known terminals or can be determined by them. According to a second nonlimiting example, the variation of the central frequencies FP and FI1 is linear, for example according to the following expressions: FP (t) = Fo + Ef.t FI1 (t) = FP (t) + AF1 expressions in which EF corresponds to a predefined variation slope. In the foregoing expressions, the center frequency FP of the pilot signal SP is preferably maintained within the frequency band BP. For example, if the variation slope EF is positive, then the center frequency FP gradually increases from the frequency FP1 to the frequency FP2. When the central frequency FP reaches the frequency FP2, it begins again to grow from the frequency FPI, and so on. In other examples, the temporal variation of the center frequencies FP and F11 may be discontinuous. Where appropriate, the center frequency FP and F11 follow, for example, predefined frequency hopping patterns. It should be noted that, unlike the frequency deviation AF1, the frequency hopping patterns are not known to the terminals 20. However, it may be advantageous if the frequency band BP is known to the terminals or can be determined by these. FIG. 4 diagrammatically shows a particular embodiment of a method 50 for transmitting a broadcast signal. In addition to the steps already described with reference to FIG. 3, the transmission method 50 illustrated in FIG. 4 comprises a step 54 for forming another information signal SI2. The broadcast signal transmitted comprises the pilot signal SP and the information signals S11 and SI2, and said information signal SI2 is transmitted on a central frequency FI2 having a frequency difference AF2 predetermined with respect to the central frequency FP of the signal SP driver, the frequency difference AF2 is different from the frequency difference AF1. As the frequency deviation AF1, the frequency difference AF2 can be constant over time, or vary over time, since it is known a priori terminals 20. In the following 20 of the description, we is placed in a nonlimiting manner in the case where the frequency difference AF2 is constant over time. FIG. 5 schematically shows, in the frequency domain, a nonlimiting example of a broadcast signal comprising the pilot signal SP, the information signal S11 and the information signal SI2, in which the central frequency FP of the pilot signal SP and the central frequency F1 of the information signal SI2 are connected by the following expression: FI2 = FP + AF2 In the nonlimiting example illustrated in FIG. 5, the frequency differences AF1 and AF2 are both positive, and the frequency difference AF2 is greater than the frequency difference AF1. For example, the frequency difference, 8, F1 is equal to 200 Hertz and the frequency difference AF2 is equal to 700 Hertz. In addition, the information signal S11 and the information signal SI2 do not overlap with each other in the frequency domain.
    [0017] More generally, what has been previously described for the frequency difference AF1 is also applicable for the frequency difference AF2. In particular, in the case where the central frequencies FP and F11 of the pilot signal SP and of the information signal S11 vary over time, then the central frequency F12 of the information signal S12 also varies over time, preferably so that the frequency difference AF2 remains constant. Several uses are possible for the information signal S12. For example, the information signal S12 may be identical to the information signal S11. In such a case, the information signal S12 is transmitted mainly for redundancy purposes, for example to improve the robustness of the interference diffusion signal, alternatively or in addition to the temporal variation of the center frequencies of the pilot signal SP and information signals S11 and S12. In another example, the information signal S12 may be different from the information signal S11. For example, the information signal S12 may be formed from broadcast information different from that used to form the information signal S11. Alternatively or in addition to the use of different broadcast information, the information signal S12 may be formed according to a physical layer protocol different from that used to form the information signal S11. By "different physical layer protocol" is meant that the broadcast signal S12 is different from the information signal S11 even when the broadcast information is the same. For example, the information signal S11 and the information signal S12 may differ in bit rate, error correction code, control information, and the like. In the nonlimiting example illustrated in FIG. 5, the information signal S12 has a spectral width greater than that of the information signal S11, for example equal to 600 Hertz. In such a case, the information signal S11 is for example intended for a first group of terminals 20 compatible with a first physical layer protocol, and the information signal S12 is intended for a second group of terminals 20 compatible with a second physical layer protocol. In preferred embodiments, the information signal 301 and the information signal S12 differ at least in the modulation used. For example, one of said information signals is modulated according to a BPSK modulation and the other of said information signals is modulated according to a GFSK modulation.
    [0018] It should be noted that while the uplink messages transmitted by the terminals 20 are ultra-narrowband in a UNB wireless communication system, the broadcast signals themselves are not necessarily ultra-narrowband and may have a wide width. instantaneous spectral greater than one kilohertz. In preferred embodiments, the information signal SI1 is ultra-narrowband. Preferably, in the case where the broadcast signal comprises several information signals, each of said information signals is ultra-narrow band. B) Broadcast signal reception method In general, many reception methods may be implemented to receive the broadcast signal, and more particularly to detect the broadcast signal and / or extract the broadcast information from the signal. information SI1 (and, if appropriate, the information signal SI2). However, because of the particular shape of the broadcast signal, in particular the predetermined frequency deviation AF1 between the pilot signal SP and the information signal SI1, the reception of the broadcast signal can be carried out simply and economically. . FIG. 6 schematically represents the main steps of a method 60 for receiving, by a terminal 20, a broadcast signal transmitted by the access network 30 in accordance with what has been described above.
    [0019] For example, each terminal 20 comprises a processing module (not shown in the figures), comprising one or more processors and storage means (magnetic hard disk, electronic memory, optical disk, etc.) in which a product is stored. computer program, in the form of a set of program code instructions to be executed to implement the different steps of the broadcast signal receiving method 60. In one variant, the processing module comprises one or more programmable logic circuits, of the FPGA, PLD, etc. type, and / or specialized integrated circuits (ASIC) adapted to implement all or part of the said steps of the method 60 of FIG. broadcast signal reception. Each terminal 20 furthermore comprises wireless communication means, considered as known to those skilled in the art, enabling said terminal to send up messages and to receive descendant messages in the form of radio signals. In other words, each terminal 20 comprises a set of means configured in software (specific computer program product) and / or hardware (FPGA, PLD, ASIC, etc.) to implement the various steps of the method 60 broadcast signal reception.
    [0020] As shown in FIG. 6, the broadcast signal reception method 60 firstly comprises a step 61 for non-linear filtering of the signal received by the terminal 20. By "non-linear filtering" is meant a filtering comprising a substantially quadratic effect, i.e. the output signal of which has the squared input signal. Indeed, if we consider, for example, the following expressions of the pilot signal SP and of the information signal SI1: SP (t) = sin (wFp.t) S11 (t) = Asii (t) -sin (wni. t) expressions in which: 20 - wFp corresponds to the frequency associated with the central frequency FP, - Asii (t) corresponds to the information signal S11 (t) in the baseband, - wni corresponds to the frequency associated with the frequency Central F11. Then the broadcast signal SD is equal to: SD (t) = sin (wFp.t) + Asii (t). sin (wHi.t) 25 After non-linear filtering, the signal obtained comprises the SD broadcast signal squared: (SD (t)) 2 = (sin (wFp.t) + (t) .sin (wni .t )) 2 = (sin (wFp.t)) 2 + (Asii (t) -sin (wni .t)) 2 + 2 (sin (wFp.t) .Asi1 (t) -sin (wni .t)) = (1 - cos (2.wFp.t)) / 2 + (Asii (t)) 2. (1 - cos (2.wni 1)) / 2 + Asii (t). (Cos (wFp.t - .t) - cos (wFp.t + wni .t)) = (1 + Asii (t) 2) / 2 + Asii (t) -cos (wAn.t) - cos (2.wFp1) / 2 - (Ali (t)) 2.cos (2.wni 1) / 2 - Asii (t) -cos (wFp.t + WFI1.t) expression in which wAF1 corresponds to the pulse associated with the frequency difference AF1. Therefore, the signal obtained after nonlinear filtering comprises, among other components, the following component: Asii (t). cos (WpFi t) 5 which corresponds to the information signal SI1 on the frequency AF1. The other components obtained may possibly, if necessary, be entirely or partially removed by a suitable filtering. Therefore, by the nonlinear filtering and the particular shape of the broadcast signal, the information signal SI1 is brought back to a frequency AF1. The nonlinear filtering may for example be carried out by means of a saturated amplifier or by means of an envelope detector circuit, and can therefore be realized simply and economically. It should be noted that the signal supplied at the input of the non-linear filter corresponds to a signal measured in a frequency band comprising the broadcast signal SD. This measured signal can optionally be translated into frequencies to lower frequencies, without this having an impact on the reception of the broadcast signal since the frequency difference AF1 is not changed by such frequency translation. Then, the reception method 60 comprises a step 62 of seeking a broadcast signal from the signal obtained, after non-linear filtering, on the frequency AF1. The broadcast signal search consists of checking whether the signal obtained on the frequency AF1 satisfies a predefined detection criterion. For example, the detection criterion can be considered as verified if the energy received on the frequency AF1 is greater than a predefined threshold value. According to another nonlimiting example, it is possible to reduce the signal obtained on the frequency AF1 to the baseband and to correlate it with a predefined temporal synchronization pattern included in the information signal S11, the detection criterion being considered as checked whether the result of the correlation exceeds a predefined threshold value.
    [0021] The execution of the search step 62 continues as long as no broadcast signal is detected (reference 620 in FIG. 6). When a broadcast signal is detected (reference 621 in FIG. 6), then the receiving method 60 includes a step 63 of extracting the broadcast information included in the information signal S11. It should be noted that, once a broadcast signal detected from the signal obtained after nonlinear filtering, the extraction can be performed from the information signal SI1 on the central frequency F11, before non-linear filtering. However, it may be necessary, in such a case, to have relatively high frequency synthesis means. In preferred embodiments, the broadcast information of the detected broadcast signal is extracted from the information signal SI1 obtained, after nonlinear filtering, on the frequency AF1. Such arrangements are very advantageous insofar as the extraction of the scattering information can be carried out with poorly performing frequency synthesis means. Indeed, the frequency AF1 is in principle accurate (generated by the base stations 31) and can be chosen low, for example of the order of a few hundred Hertz. Therefore, even with poorly performing frequency synthesis means, the drift of the frequency AF1 generated by the terminal 20 is in principle negligible over a period of seconds to minutes. For example, the extraction of the broadcast information comprises the open-loop generation of a sinusoidal signal of frequency AF1, and the multiplication of the signal obtained after nonlinear filtering by said sinusoidal signal of frequency AF1. Nothing, however, excludes generating said sinusoidal signal of frequency AF1 in a closed loop, for example by means of a PLL, a Costa loop, etc. In the case where the broadcast signal SD further comprises an information signal SI2, and in the case where the reception of the broadcast signal SD comprises a nonlinear filtering step, then the frequency difference AF1 and the difference frequency AF2 are preferably chosen so as to ensure that, after nonlinear filtering, the information signal SI1 and the information signal SI2, respectively brought back to the frequency AF1 and the frequency AF2, are not too much disturbed by other components.
    [0022] For example, by denoting by B1 the spectral width of the information signal SI1 and by B2 the spectral width of the information signal SI2, then it is possible to choose the frequency deviations AF1 and AF2 so that the following expressions are checked (assuming AF2> AF1): 3036907 19 Bi + B2 / 2 <AF2 - B1 / 2 + B2 <AF1 The expressions above make it possible to ensure, in the case of a purely quadratic effect of the nonlinear filtering, that the information signal SI1 and the information signal SI2, obtained on the frequencies AF1 and AF2, do not have a frequency overlap with other components of the signal obtained after non-linear filtering. If the non-linear filtering is not limited to a quadratic effect, then the frequency deviations AF1 and AF2 are preferably chosen so that the frequency difference AF2 is not a harmonic of the frequency difference AF1 (and conversely if the frequency difference AF1 is greater than the frequency difference AF2). More generally, it is possible to choose the frequency differences AF1 and AF2 by simulation of the non-linear filtering on an SD broadcast signal, by varying the respective values of the frequency deviations AF1 and AF2 to ensure that the information signals 5I1 and SI2, brought back to the frequencies respectively AF1 and AF2, are not too disturbed by the other components of the signal obtained after nonlinear filtering. More generally, it should be noted that the embodiments and embodiments considered above have been described by way of nonlimiting examples, and that other variants are therefore possible. In particular, the invention has been described by considering a broadcast signal comprising one or two information signals. According to other examples, nothing excludes the consideration of a broadcast signal comprising a number of information signals greater than two, transmitted, if necessary, on respective central frequencies having predetermined different respective frequency deviations with respect to the central frequency of the pilot signal SP, a priori known terminals.
    权利要求:
    Claims (3)
    [0001]
    CLAIMS1 - Method (50) for transmitting a broadcast signal by an access network (30) to a plurality of terminals (20) of a bidirectional wireless communication system, characterized in that said method (50) comprises: - forming (51) an information signal SI1 from broadcast information to said terminals (20), - forming (52) a pilot signal SP, - transmitting (53) a broadcast signal comprising the information signal SI1 and the pilot signal SP, said information signal SI1 and said pilot signal SP being transmitted on respective different central frequencies having a predetermined frequency difference AF1. Method (50) according to claim 1, comprising the formation of another information signal SI2, said information signal SI2 being transmitted on a center frequency having a frequency difference AF2 predetermined with respect to the center frequency of the pilot signal SP , the frequency difference AF2 being different from the frequency difference AF1. The method (50) of claim 2, wherein the information signal SI2 is formed from the same broadcast information as that of the information signal S11. The method (50) of claim 2, wherein the information signal SI2 is formed from broadcast information distinct from that of the information signal S11. Method (50) according to one of claims 2 to 4, wherein the information signal SI1 and the information signal SI2 are formed according to different respective physical layer protocols. Method (50) according to claim 5, wherein the information signal SI1 and the information signal SI2 are formed according to different modulations. Method (50) according to one of the preceding claims, wherein the respective central frequencies of the pilot signal SP and each information signal vary over time, the frequency difference between the 10
    [0002]
    2 - 15
    [0003]
    3 - 204 - 5 - 25 6 - 30 7 - 3036907 21 center frequency of the pilot signal SP and the central frequency of each information signal being constant over time. 8 - Method (50) according to one of the preceding claims, wherein the pilot signal SP is a sinusoidal signal. 9 - Process (50) according to one of the preceding claims, wherein the frequency difference AF1 is less than 10 kilohertz, preferably less than 1 kilohertz. - Method (50) according to one of the preceding claims, wherein the information signal SI1 is ultra-narrow band. 11 - Base station (31) characterized in that it comprises means configured to implement a method (50) of emission according to one of the preceding claims. 12- access network (30) characterized in that it comprises means configured to implement a method (50) of emission according to one of claims 1 to 10. 13- A method (60) for receiving, by a terminal (20), a broadcast signal emitted according to a transmission method (50) according to one of claims 1 to 10, characterized in that it comprises the non-linear filtering (61) of a signal received by the terminal (20), the search (62) of a broadcast signal from a signal obtained, after non-linear filtering of the received signal, on the frequency AF1, a diffusion signal being detected when said signal obtained on the frequency AF1 satisfies a predefined detection criterion. 14- Method (60) according to claim 13, comprising extracting (63) broadcast information broadcast signal detected from the signal obtained after nonlinear filtering on the frequency AF1. 15- Terminal (20) characterized in that it comprises means configured to implement a method (60) for receiving according to one of claims 13 to 14.
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    同族专利:
    公开号 | 公开日
    BR112017025285A2|2018-08-07|
    EP3286938A1|2018-02-28|
    MX367232B|2019-08-09|
    WO2016193592A1|2016-12-08|
    US10560827B2|2020-02-11|
    MX2017015218A|2018-02-19|
    EP3286938B1|2018-08-22|
    HK1248961A1|2018-10-19|
    US10645555B2|2020-05-05|
    JP2018524857A|2018-08-30|
    CN107667549A|2018-02-06|
    SG11201709690PA|2017-12-28|
    US20200053535A1|2020-02-13|
    CN107667549B|2020-06-19|
    US20180132087A1|2018-05-10|
    FR3036907B1|2017-07-14|
    JP6920215B2|2021-08-18|
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    法律状态:
    2016-05-31| PLFP| Fee payment|Year of fee payment: 2 |
    2016-12-02| PLSC| Publication of the preliminary search report|Effective date: 20161202 |
    2017-05-30| PLFP| Fee payment|Year of fee payment: 3 |
    2018-05-31| PLFP| Fee payment|Year of fee payment: 4 |
    2019-05-31| PLFP| Fee payment|Year of fee payment: 5 |
    2020-05-29| PLFP| Fee payment|Year of fee payment: 6 |
    2022-02-11| ST| Notification of lapse|Effective date: 20220105 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1554890A|FR3036907B1|2015-05-29|2015-05-29|METHODS OF TRANSMITTING AND RECEIVING A BROADCAST SIGNAL COMPRISING A PILOT SIGNAL AND AN INFORMATION SIGNAL|FR1554890A| FR3036907B1|2015-05-29|2015-05-29|METHODS OF TRANSMITTING AND RECEIVING A BROADCAST SIGNAL COMPRISING A PILOT SIGNAL AND AN INFORMATION SIGNAL|
    JP2017561812A| JP6920215B2|2015-05-29|2016-05-27|A method for transmitting and receiving broadcast signals including pilot signals and information signals|
    SG11201709690PA| SG11201709690PA|2015-05-29|2016-05-27|Methods for transmitting and receiving a broadcast signal comprising a pilot signal and an information signal|
    PCT/FR2016/051267| WO2016193592A1|2015-05-29|2016-05-27|Methods for transmitting and receiving a broadcast signal comprising a control signal and an information signal|
    CN201680031062.6A| CN107667549B|2015-05-29|2016-05-27|Method for transmitting and receiving broadcast signal including pilot signal and information signal|
    MX2017015218A| MX367232B|2015-05-29|2016-05-27|Methods for transmitting and receiving a broadcast signal comprising a control signal and an information signal.|
    BR112017025285-6A| BR112017025285A2|2015-05-29|2016-05-27|methods for transmitting and receiving a broadcast signal comprising a pilot signal and an information signal|
    EP16733640.3A| EP3286938B1|2015-05-29|2016-05-27|Methods for transmitting and receiving a broadcast signal comprising a control signal and an information signal|
    US15/577,763| US10560827B2|2015-05-29|2016-05-27|Methods for transmitting and receiving a broadcast signal comprising a pilot signal and an information signal|
    HK18108489.1A| HK1248961A1|2015-05-29|2018-07-03|Methods for transmitting and receiving a broadcast signal comprising a pilot signal and an information signal|
    US16/660,163| US10645555B2|2015-05-29|2019-10-22|Method for receiving a broadcast signal comprising a pilot signal and an information signal|
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