Jamming detection and alarm emission device for a jammed NB-IoT network

Abstract

The present invention relates to an NB-IoT jamming detection device implementing a specific configuration to ensure the emission and transmission of an alarm signal in the presence of a jammer affecting the NB-IoT network. In particular, the invention offers several possible communication methods in jamming mode, notably by sending the alert signal over the NB-IoT network and according to a network version, whether the new version 16, known as release 16, or the previous version. Advantageously, the invention also proposes to enhance transmission security by implementing a jamming-resistant gateway function that allows the alert signal to be relayed within a local or nearby network. Finally, the invention also relates to the configuration of the jamming detection device for detecting jamming on the NB-IoT network and an alarm system incorporating the device of the invention.

Description

Title of the invention: Device for detecting jamming and transmitting an alarm on a jammed NB-IoT network FIELD OF THE INVENTION

[0001] The present invention relates to the field of radio frequency communication on the 3GPP networks of so-called NB-IoT and LTE-CAT-M operators. In particular, the invention relates to a security alarm device for delivering an alert signal directly or indirectly on a jammed low-speed and low-power NB-IoT and LTE-CAT-M network. TECHNOLOGICAL BACKGROUND

[0002] Many alarm systems are available on the market today to protect homes and, in general, private property and also people. The most sophisticated alarm systems are equipped with infrared or radar sensors to detect an intrusion in an external perimeter or inside a house. Following the detection of an intrusion, the system triggers a deterrent device (i.e. siren, smoke generator, fog generator), and if necessary sends an intrusion alarm to a remote monitoring base.

[0003] In general, burglars, to prevent the alarm system from being triggered and sending this intrusion information to the service operator, use portable jammers to inhibit this transmission.

[0004] Depending on the type of jammer used and the type of signal to be interfered with, the disruption of communication between the transmitter and the receiver will be more or less effective.

[0005] The use of transmission techniques such as the ultra-narrowband (UNB) communication technique or the SS-Spread Spectrum technique have been suggested as technical solutions for transmitting signals in the face of jamming.

[0006] For its part, UNB modulation uses the spectrum efficiently and resists interference since all the energy is concentrated in a very narrow bandwidth. Patent EP 3 477 611 B1 gives an example of an alarm system comprising a radio component configured to send an alert signal on the ISM or GSM band without jamming detection, and to an LPWAN network in unidirectional mode in the event of radio jamming detection.

[0007] Unlike networks with a single-way LPWAN link (Sigfox, LORA), low-power NB-IoT and LTE-CAT-M networks are bidirectional and the equipment “UE” and the base station “eNB” communicate cyclically according to a protocol illustrated in [Fig.l]. In addition, the equipment must receive the narrowband random physical access channel "NPRACH". The NPRACH is dedicated to the transmission of the NB-IoT preamble, which is the first signal transmitted by the UE to the eNB in ​​order to request access to the network. To do this, the UE equipment must also be able to synchronize with the station to be able to transmit frames in the transmission channel very precisely. However, in the case of a jammer at the equipment level, the latter will not be able to receive the NPRACH channel necessary for the transmission of the alert signal. The present invention therefore aims to propose a solution for reconnecting the equipment to the network and transmitting an alert signal in the presence of jamming.

[0008] More particularly, the invention aims to guarantee the transmission of the alert signal in the presence of jamming affecting all networks by proposing a solution for sending an alert signal on the jammed NB-IoT network and programming the device with an auxiliary function of a jamming-resistant alert signal gateway. Statement of the invention

[0009] The present invention proposes a jamming and alert detector comprising a radio communication module compatible with an NB-IoT network.

[0010] A first aim of the invention is to configure said radio communication module to allow reconnection to the network in the presence of interference.

[0011] A second aim of the invention is to configure said radio communication module to generate and transmit an alert signal in the event of jamming detection.

[0012] A third aim of the invention is to propose an auxiliary backup function to guarantee reception of the alert signal by the remote monitoring center.

[0013] Finally, a fourth aim of the invention is to propose a method for detecting interference specific to the NB-IoT network.

[0014] For these purposes, the invention proposes a jamming detection device for an alarm system intended to be installed in a fixed position, characterized in that the device comprises a communication module configured according to a first operating state without jamming to connect to the NB-IoT network, exchange data and synchronize to said network cyclically, as well as to save a connection profile to said NB-IoT network, said connection profile comprising at least: - a reference to a designated base station for said device; and -preferably, a propagation time between said device and the base station.

[0015] In particular, the device is configured according to an initial operating state allowing for an optimal response when jamming is detected, and therefore unable to receive messages from the base station to re-establish the network reconnection context. In fact, the said connection profile includes the first elements necessary for the transmission of the alert signal and is normally transmitted by the base station.

[0016] In its non-interference operating state El, the device may also be configured according to one of the following characteristics or any technically operable combination of these characteristics:

[0017] - the device is configured in normal and / or low coverage mode power consumption such as eDRX or PSM mode;

[0018] - the radio communication module comprises a local oscillator configured in mode pulsed listening to wake up and receive DCI blocks (DCI stands for Downlink Control Information), preferably every minute. This feature helps optimize synchronization to the NB-IoT network;

[0019] -the device is configured with a gateway function of an alert signal frame from a neighboring device to said base station;

[0020] -the device is configured to connect with a second device according to the invention or an NB-IoT gateway, and exchange connection maintenance data according to a predefined frequency.

[0021] The device of the invention is also configured according to a second operating state triggered in the presence of jamming and allowing the emission and transmission of an alert signal to the base station. The second operating state comprises one or all of the following characteristics in any technically operable combination:

[0022] - the device is configured to generate and save an alert signal frame, and order its transmission with multiple repetitions, and preferably until receipt of a confirmation of reception by the base station;

[0023] -, the radio communication module is configured to reconnect to the network on the basis of said connection profile, and preferably in an extreme coverage mode to increase the number of repetitions;

[0024] - the radio communication module comprises a radio component NB-IoT transmitting / receiving device configured to transmit the alert signal frame by changing subcarrier frequency and so as to cover a set of subchannels in the band allocated to said device for transmitting on said NB-IoT network;

[0025] - said allocated band is 180 kHz, the sub-channels are 15 kHz, and a subcarrier frequency is changed over 12 possible subchannels of said allocated band;

[0026] - the alert signal frame is transmitted with multiple repetitions over the time of a slot+delta t ;

[0027] - the device is configured to transmit an alert signal frame with spread spectrum and / or narrowband to a second device according to one of the preceding claims connected to said device.

[0028] The invention also relates to the configuration of the device for detecting a jamming event.

[0029] In particular, the radio transmit / receive component of the radio communication module is also configured to detect the presence of jamming and alternately to receive / transmit data to said NB-IoT network, or the radio communication module comprises a dedicated radio receive component to detect the presence of jamming.

[0030] In order to detect an interference event on the NB-IoT network, the device is configured to divide the 180 kHz band allocated to said device in the NB-IoT network into several sub-bands of a predefined frequency width such as 1 MHz, and to measure a signal indicative of the power in reception of the RSSI noise in said sub-bands, and in which an interference detection event is identified according to a configurable minimum of power measured in at least one or more sub-bands analyzed, or of a single average power in said sub-bands.

[0031] Preferably, the sub-bands have a width of 1 MHz and / or wherein said sub-bands are re-divided into 180 kHz channels, and wherein an interference detection event is identified based on a configurable minimum of power measured in at least one or more of said analyzed channels, or a single average power in said 180 kHz channels.

[0032] Finally, the invention also relates to a security alarm system comprising a jamming detection device according to the invention.

[0033] Other advantages, aims and particular characteristics of the present invention will emerge from the description which follows, given for explanatory and in no way limiting purposes, with reference to the appended drawings.

[0034] PRESENTATION OF FIGURES

[0035] [Fig.l] Schematically illustrates the data exchange of an NB-loT equipment (UE) with the base station (eNB) according to the state of the art.

[0036] [Fig.2] Illustrates a jamming detection device according to the invention in two-way communication with a base station.

[0037] [Fig.3] Illustrates the configuration of the device of the invention according to two operating states.

[0038] [Fig.4] Illustrates the framing system in the NB-IoT network.

[0039] [Fig.5] Illustrates a jamming device and two embodiments of the radio communication module according to the invention.

[0040] [Fig.6] Illustrates an alarm system comprising a device according to the invention.

[0041] [Fig.7] Schematically illustrates the general configuration of the device of the invention according to a preferred embodiment.

[0042] [Fig.8] Schematically illustrates the data exchange of an NB- equipment (UE) loT in “release 16” version with the base station (eNB).

[0043] [Fig.9] Schematically illustrates the reception of DCI blocks for synchronization to the NB-IoT network.

[0044] DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0045] The invention proposes a jamming detector device 10 for an alarm system ( [Fig.2]), said device comprising a radio communication module 100, compatible with an NB-IoT and / or LTE-CAT-M network, and making it possible to transmit an alert signal on said jammed network. In particular, the invention proposes several possibilities and means of possible exchanges in jamming mode, and in particular by sending the alert signal on the NB-IoT network and in accordance with a version of the network, whether the new version 16, called release 16, or the previous version. Advantageously, the invention also proposes to reinforce the sending security by also implementing a jamming-resistant gateway function and making it possible to relay said alert signal in a local or nearby network.

[0046] The first objective of the invention is therefore to optimize the connection to the NB-IoT network of the device during the detection of jamming for the transmission of the alert signal on the NB-IoT network, in version release 16 or in earlier version.

[0047] When connecting to the NB-IoT network in the absence of interference, a device is attached to the network according to predefined procedures in several phases. During a first registration phase, the UE device defines the connection parameters with a base station 30 so as to create a connection profile, to then connect to the network and communicate with the base station according to the parameters defined in said connection profile.

[0048] The present invention proposes to configure the device of the invention according to at least two operating states ([Fig. 3]). According to a first operating state E1 in the absence of jamming, the invention proposes to configure the jamming detector device 10 according to a so-called “normal” coverage mode and a low energy consumption operating mode, such as eDRX (Extended Dis-continuous Reception) or PSM (Power Save Mode). This configuration allows the jamming detector to have a long life. Indeed, it must be considered that the detection of jamming is a very rare event, and that the battery-powered device must remain autonomous for at least four years. The eDRX and PSM operating modes obviously make it possible to meet this need. The normal coverage mode also defines and furthermore the number of repetitions for the transmission of frames from the equipment to the base station, and vice versa. This “normal” coverage mode is not limiting, nor are the eDRX and PSM modes, the main thing being that the device is configured to exchange data and synchronize with the network periodically. Indeed, when the jamming detector device 10 is put into service, it registers, and begins cycles of data exchange with the base station 30 in non-jammed conditions. Thus, once in operation, the device is synchronized to the network at each cycle of connection to the base station.

[0049] Advantageously, the invention proposes to configure the device 10 to register with the network and save its connection profile, said connection profile comprising: - an identifier of the jamming detector device 10;

[0050] - a reference of the base station 30 comprising the best connection with said jamming detection device as well as security elements (encryptions).

[0051] By retaining its registration profile, it is possible to move directly to the connection or attachment phase to the network, and therefore to optimize the generation and transmission of the alert signal. Indeed, the registration phase is normally repeated at each connection in the equipment of the state of the art, which generates a loss of several seconds in each connection to the network. In contrast, in the context of the invention these seconds are precious, and the invention proposes a solution making it possible to move directly to the connection phase thanks to the saving of the connection profile. Moreover, in the presence of jamming, the device is already in possession of the first data necessary for the transmission of the alert signal, and which it cannot receive from the base station, i.e. its identifier, the reference of the base station designated for the device 10 and the propagation time between the device 10 and the base station 30.

[0052] Regardless of the version of the NB-IoT network “release 16” or “previous release”, in one embodiment the device is configured with an eDRX or PSM reception cycle set to a low value to ensure the synchronization (CellD, TimeSlot, frequencies) of the device, and the reception of the first three NPSS frames (from the English “Narrowband Primary synchronization signal”), NSSS frames (from the English “Narrowband secondary synchronization channel”), and NPBCH frames (from the English “Narrowband physical broadcast channel”) (see [Fig.l]).

[0053] Synchronization with the network

[0054] To be able to transmit a data frame (NPUSCH) or a resource allocation request (NPRACH) the equipment must be synchronized. In fact, two parameters are essential (timing and frequency).

[0055] Normally these are received in the NPSS & NSSS frame and the transmission must be done after the reception of the DCI block which is repetitive ([Fig.9]).

[0056] However, in the event of interference, as reception is disturbed, it will not be possible to be correctly timed (to be in the correct slot with 30 / 50 microseconds of precision and also on the correct frequency received by the station.

[0057] Any drifts will cause collisions and the message will not be decoded. This synchronization is done at the physical level of the NB-IoT protocol.

[0058] In order to overcome this difficulty, the invention proposes to configure the radio communication module 100 in pulsed listening mode and therefore to wake up every minute to search for the DCI information blocks and thus to be synchronized at the symbol and frequency level. For obvious reasons of consumption a local oscillator (quartz) will be used and its frequency and temperature automatically corrected according to the information blocks.

[0059] Thus the maximum drift will be low during each minute.

[0060] Indeed, if a jammer is detected, the last block received will be used. The additional consumption cost can be estimated by applying the duty cycle ratio, 1 minute divided by 10ms (which is the maximum duration of a block of 10 frames) but which can be reduced to 1ms.

[0061] Let's take as a radio parameter 40mA in reception so this consumption will be 40000 / 60000 / 10 = 6.6 uA.

[0062] The quartz that will only serve this function will be of the highest possible precision, we can also adjust the duty cycle accordingly. We will preferably choose a watchmaker's quartz (32768Hz) with as parameter a Gm crit or drive level as low as possible ( <luW). De préférence, et afin d’améliorer la tolérance en fréquence, les capacités de l’oscillateur seront intégrées au microcontrôleur du module de communication radio et ajustées par logiciel en modifiant la valeur de charge (Cl), ce qui donnera une grande précision et si on constate un écart entre deux valeurs de mesure des blocs d’informations venant du réseau. L’oscillateur est par exemple le Jauch JTX-310-6-32.768 ou le Abracom ABS06-107-32.768.

[0063] In one embodiment, the device of the invention is configured according to an eDRX operating mode set to a maximum value of 43 minutes or in PSM mode with a 60-minute wake-up window having a very high probability of allowing communication to the network before the jamming occurs. That is to say that the device, and in particular the radio communication module, will indicate to a remote application that the latter is still operational (called keepalive function) by means of a connection made every 43 to 60 minutes, which is a good compromise with energy consumption. Each data transmission cycle allows, in addition to the keepalive function, “keepalive” connection to resynchronize to the network.

[0064] The second objective of the invention is to configure the device according to a second state E2 to transmit an alert signal in the presence of jamming.

[0065] Depending on the network version (Release 16 or not) and as already mentioned, the device 10 connects to the network and transmits by means of the radio communication module the frame "NPRACH message 1" (NPRACH 1 acronym for "Narrowband physical random access channel") requesting the base station to obtain resources allocated for the device to send the context restoration frame and the transmission of data grouped in the same message, i.e. the frame NPUSCH message 3 (NPUSCH is the acronym for "Narrowband physical uplink shared channel"). However, in the presence of interference, the device is not able to fully receive the NDPSCH message 2 frame (NDPSCH is the acronym for "Narrowband physical downlink shared channel").

[0066] Advantageously, due to the saving of the connection profile, the device of the invention already has the first parameters necessary for sending the NPUSCH frame, i.e. its connection identifier, the reference of the allocated base station and a propagation time between said base station 30 and the device 10. The device therefore only lacks the narrowband random physical access channel necessary for transmitting data to said base station.

[0067] This, by means of a mechanism of repetition of the sequence message 1, message 2, increases the probability of receiving the missing elements for message 3 corresponding to that of the alert signal frame.

[0068] Other unreceived items will be simulated as follows.

[0069] The invention proposes to configure a transmitter E, a transmitter / receiver E / R or NB-IoT transceiver of the radio communication module to transmit an alert signal frame by changing the subcarrier frequency on the 12 possible frequency channels allocated to data transmission. Indeed, depending on the geographical position of the device and the operator of the NB-IoT network, a 180 kHz band is reserved for all communications of the equipment, and these 180 kHz are divided into 15 kHz channels for the exchange of information blocks (see [Fig.4]). Consequently, this gives 12 possible frequency channels that the base station could have allocated to the device of the invention for the transmission of the alert signal.

[0070] Advantageously, the invention also proposes to repeat the frame of the alert signal for the time of a slot + delta t (delta t being a multiple of 1 ms) and for several seconds. It is thus possible to overcome a possible collision of the frame of the alert signal with the NPDSCH and NPRACH frames. Similarly, the invention proposes to transmit the alert signal frame at a maximum transmission power or at least at a transmission power > 10 dBm, and which is in one embodiment the maximum power of 23 dBm. This transmission power makes it possible to guarantee reception by the base station, the latter requiring at least 10 dBm to demodulate the signal. PURE PROTOCOL

[0071] In contrast to the technique used previously and illustrated in [Fig.l], the “release 16” version of the NB-IoT proposes the PUR protocol (from the English “Preconfigured uplink resource”) to optimize the exchanges of messages during a data transmission by reducing the number of exchanges necessary with the base station before the transmission of the alert signal frame.

[0072] The configuration of the uplink resource must be carried out in connected mode ([Fig.8]); the size of the message to be sent and the number of exchanges and the delay between these exchanges are then defined. The network then reserves the resource and goes into inactive mode (low power). When a jammer is detected, a connection resumption message called in English "connection summary" is sent with the data (a concept equivalent to message 3, see [Fig.l]). The number of exchanges allows either to have longer data or to make it more reliable by repetitions. However, this possibility of the PUR protocol does not exclude resynchronization with the network as described in this patent.

[0073] Regardless of the embodiment and version of the network, the invention proposes to estimate the power between the jammer and the device according to the following formula PC=log (width of the jammed bandwidth / width of an NB-IoT channel. For example, for a bandwidth of 20 MHz, Pc=101og (20MHz / 15kHz)=log(1333)=-31dBm. If we consider that the maximum power of the device is 23 dBm and that of the portable battery-powered jammer is 30dBm (1W) for its entire 20 MHz band, the power of the jammed signal in a 15kHz channel will be 30-31= -IdBM. With a transmission power of 23 dBm, the signal from the device will then be 24 dBM stronger than that of the jammer on the reception side by the base station (signal / noise = 23+l=24dBm).

[0074] In order to maximize the probabilities of receiving the alert signal, the invention also proposes to transmit the NPRACH / NPUSCH frame or the equivalent in PUR according to an extreme coverage mode. In this way, the base station will allocate more repetitions to the exchanges with the device of the invention, and the transfer of the alert signal will thus be statistically improved. For example, a Sigfox sending frame is transmitted three times to have a success rate >90%. In the present invention, the frame repetition is between 8 and 2048 (PUR and non-PUR).

[0075] Of course, the jamming detector device 10 also comprises a radio receiver R or transceiver E / R configured to monitor the presence of interference on the GSM band in a known manner, for example, as described in patent EP3477611B1 from Telecom Design. As illustrated in incises a) and b) of [Fig.5], said receiver R may be the one dedicated to the transmissions / receptions of the radio communication module 100 ([Fig.5](a)) or be an additional receiver R or transceiver E / R dedicated ([Fig.5](b)) to said jamming detection.

[0076] The device of the invention also comprises electrical power supply means A, such as a battery, an electronic card 3 integrating processing means T, calculation means C and storage means M such as a microcontroller-based calculator provided with analog / digital and digital-analog conversion means, performing processing of the signal provided by the radio communication module 100, and possibly a presence detector 7 optionally integrated into said device 10 or being detached from said device 10 and communicating according to a secure communication protocol adapted to the presence of jamming, and as described in patent EP3716242A1 from Telecom Design.

[0077] The third objective of the invention is to configure the radio communication module to detect the presence of interference affecting the NB-loT communication network. That is to say by working exclusively in the channel width of 180khz.

[0078] Table 1 below illustrates an example of the distribution of bands and frequency ranges allocated for communications of equipment in the NB-loT network.

[0079] [Tables 1] te Stessssg & Z À 18^ - WK 1938 ■ 1$S0 ................$ 3 - * a-;' § O34 ■ ? B 880-515 sssssssssssssssss; 12 ® ' 71B 53 - 787 746--788 .......................................... 17 734-748 18 Sis ■ 8S8 880--878 | is ..................................................................................... -----¾ ai O-SS? 731 • sa a 814- W ”ï 28 703 74S 758 ■ sas ms -1 w 3''0-3208

[0080] The analysis of the band is therefore more or less difficult depending on this bandwidth. For example, band No. 20 with a width of 30 MHz is allocated in France, and with a state-of-the-art jamming detector, the analysis of the signal indicative of the intensity of the received signal RSSI is difficult to achieve or not reliable enough.

[0081] In order to overcome this difficulty, the invention proposes implementing an R receiver or e / R NB-IoT transceiver configured to divide a width of the band allocated to said radio communication module into several sub-bands, and to measure an RSSI signal (indicative of the power in reception of the noise) individually and by iteration in said sub-bands. Advantageously, the invention proposes to rule out the presence of interference when at least a predefined number of sub-bands do not present a strong occupancy signal. For example, the radio communication module is configured to divide the 30 MHz band into 1 MHz sub-bands and analyze the RSSI signal which corresponds to the power level of the jammer in said sub-band. In particular, a PLL ("Phase-locked Loop" or in French, phase-locked loop (BVP) of said module is fixed in the middle of the sub-band and an RSSI signal level is measured.

[0082] In a preferred embodiment, each sub-band is re-divided into 180 kHz channels in which the 15 kHz sub-channels available for communication of the device 1 with the network are housed. Similarly, it can be deduced that if some 180 kHz channels do not have a strong signal among those available, it is not a jammer but a normal occupation by NB-IoT / LTE-Cat-M equipment close to the device of the invention. Advantageously, this technique remains very simple and can be implemented quickly to avoid consuming radio frequency resources, in particular when the transceiver for jamming detection is also dedicated to the transmissions / receptions of the radio communication module 100.

[0083] According to another embodiment, the invention proposes to configure the radio communication module 100 to automatically re-divide said 1 MHz sub-band into 180 kHz channels using the technique of a comb filter called a "combo filter" centered on the intermediate frequency of the transceiver, and which will automatically filter into channels by multiple of power 2°4 so as to optimize the calculation time. We therefore ultimately recover a field structure indicating the power by order of each channel or a single power. The Tx alert signal is therefore triggered according to a configurable minimum of power detected by channels or a single power.

[0084] The fourth objective of the invention is to configure the device of the invention with an auxiliary backup function to guarantee reception of the alert signal by the base station and the remote monitoring center.

[0085] To this end, the device is configured to save a jamming detection event during a failure to transmit the alert signal, or at least in the absence of confirmation of receipt of the alert signal Tx by the base station 30.

[0086] According to one embodiment, the device of the invention is configured to repeat an alert signal of said saved alert event as often as possible to alert the remote monitoring center.

[0087] In another embodiment, which can be combined with the preceding embodiment, the device 10 of the invention is configured to relay an alert signal Tx received by the radio communication module 100 to the base station 30 and the remote monitoring center. The device of the invention can thus also serve as a gateway for another device of the invention located in the vicinity of the device or even closer such as its garden or balcony, in a location far from the jammer facilitating the reception of the elements of the message 2. For example, it is estimated that a device located within a perimeter of two km can potentially relay receive the alert signal frame and relay it to the remote monitoring center. Indeed, a neighboring device would not be affected by the jamming, or at least not to the same extent as the device near the jammer (such as a community network).

[0088] Finally, the invention also relates to the optimization of the operation of the device of the invention for its integration into a security alarm system. More particularly and as illustrated in [Fig.6], the device 10 of the invention will be a piece of equipment detached from the alarm center, and will be configured with two types of radio links. A first radio link (illustrated in long-dash dotted lines), is the one used with the remote application server in NB-IoT / LTE-CAT-M, as already described. A second radio link in ISM band (illustrated in short-dash dotted lines) will be used to communicate with the various elements of the alarm system, such as the alarm center 15, the presence sensors 7, the deterrent device(s) 17.Furthermore, the invention proposes to configure said device to communicate with an intrusion sensor and / or a deterrent device, or an NB-IoT gateway according to a secure radio protocol with jamming proof, and as described in patent EP 3 716 242 A1 (illustrated in bold by short dashed lines).

Claims

Claims

1. Jamming detection device (10) for an alarm system intended to be installed in a fixed position, characterized in that the device comprises a radio communication module (100) configured according to a first operating state (El) without jamming and according to a second operating state in the event of jamming, and the communication module is configured in said first operating state without jamming to connect to the NB-IoT network, exchange data and synchronize to said network cyclically, as well as to save a connection profile to said NB-IoT network, said connection profile comprising at least: - a reference of a base station (30) designated for said device; and - a propagation time between said device and the base station (30).

2. Device according to claim 1, for which in the first operating state (El) the device is configured according to a so-called "normal" coverage mode and further defining a number of repetitions for the transmission of frames from the device to the base station and vice versa, and / or according to a low energy consumption coverage mode such as an eDRX or PSM mode.

3. Device according to one of the preceding claims, in which in order to optimize synchronization to the NB-IoT network, the radio communication module (100) comprises a local oscillator configured in pulsed listening mode to wake up and receive DCI information blocks, preferably every minute.

4. Device according to one of the preceding claims, wherein in the first operating state (El) the device is configured with a gateway function of an alert signal frame (Tx) from a neighboring device to said base station (30).

5. Device according to one of the preceding claims, for which in the first operating state (El) without interference and in order to ensure a gateway function, the device is configured to connect with a second device according to one of the preceding claims or an Nb-IoT gateway, and exchange connection maintenance data according to a predefined frequency.

6. Device according to one of the preceding claims, in which during a jamming detection event, the commu- radio communication is configured to operate according to the second operating state (E2) in the event of jamming, and the device is configured to generate and save an alert signal frame, and control its transmission (Tx) with multiple repetitions, and preferably until receipt of a confirmation of receipt by the base station (30).

7. Device according to one of claims 2 to 6, in combination with the characteristics of claim 3, for which in the second operating state (E2) in the event of interference, the radio communication module is configured to reconnect to the network on the basis of said connection profile, and preferably in an extreme coverage mode making it possible to increase the number of repetitions for the transmission of frames from the device with the base station, and vice versa.

8. Device according to one of claims 6 to 7, wherein the radio communication module (100) comprises an NB-IoT transmit / receive (T / R) radio component configured to transmit the alert signal frame (Tx) by changing subcarrier frequency and so as to cover a set of subchannels in a band allocated to said device for transmitting on said NB-IoT network.

9. The device of claim 8, wherein said allocated band is 180 kHz, the subchannels are 15 kHz, and a frequency of the subcarrier is changed over 12 possible subchannels of said allocated band.

10. Device according to one of claims 6 to 9, in which the frame of the alert signal (Tx) is transmitted with multiple repetitions over the time of a slot+delta t.

11. Device according to one of claims 6 to 10, wherein said frame of the alert signal is transmitted at a minimum power >10dBm, preferably >15dBm, and more preferably >20dBm, and such as 23 dBm.

12. Device according to one of claims 6 to 11, wherein in the second operating state (E2) the device is configured to transmit the alert signal frame with spread spectrum to a second device according to one of the preceding claims.

13. Device according to claim 1, wherein the radio communication module (100) comprises a radio transmit / receive (E / R) component of the radio communication module (100) configured to detect the presence of jamming and alternately receive / transmit data to said NB-IoT network, or wherein the radio communication module- radio communication (100) comprises a dedicated receiving radio component (R) for detecting the presence of jamming.

14. Device according to one of the preceding claims, wherein in order to detect the presence of interference, the device (10) is configured to divide a 30 MHz wide band allocated to said device (10) in the NB-IoT network into several sub-bands of a predefined frequency width such as 1 MHz, and to measure a signal indicative of the power in reception of the RSSI noise in said sub-bands, and in which an interference detection event is identified according to a configurable minimum of power measured in at least one or more sub-bands analyzed, or of a single average power in said sub-bands.

15. Device according to claim 14, wherein the sub-bands have a width of 1 MHz and / or wherein said sub-bands are re-divided into 180 kHz channels, and wherein the presence of interference is identified based on a configurable minimum of power measured in at least one or more of said analyzed channels, or a single average power in said 180 kHz channels.

16. A security alarm system comprising a jamming detection device according to one of the preceding claims.

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