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1. (WO2018224488) DISPOSITIF DE COMMUNICATION ET DE BROUILLAGE RADIOFRÉQUENCE ET PROCÉDÉ DE COMMUNICATION RADIOFRÉQUENCE RESPECTUEUX DE L'ENVIRONNEMENT SÉCURISÉ PHYSIQUEMENT ET DE BROUILLAGE DE COMMUNICATION RADIOFRÉQUENCE HOSTILE
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Radio Frequency Communication and Jamming Device and Method for

Physically Secured Friendly Radio Frequency Communication and for

Jamming Hostile Radio Frequency Communication

Description

The invention relates to physically secured friendly radio frequency communication in combination with jamming of hostile radio frequency communication.

For medical applications a so called "shield" device, which operates as a barrier between an implanted medical device and an outside eavesdropper, is presented in reference [1]. The system still uses cryptographic algorithms, which do not fully rely on physical secrecy communication methods.

The authors of reference [2] have studied the physical security of unidirectional link from a source node to a destination node in presence of a passive eavesdropper. The authors do not address the operation or the scheme of the jamming system neither in presence of multiple hostiles (limited to a pas-sive eavesdropper in the paper) nor maintaining a bidirectional physically-secured link between two friendly peers.

The presented work in [3] has considered a single centralized jamming source node, the base station according to paper's authors. The base station as the source of jamming signal relies on its multi- antenna configuration to introduce physical secrecy to two unidirectional links, an uplink and a downlink. The links are not geographically co-located, they are directed for two different friendly terminals. The uplink and the downlink share the same frequency band as the jamming signal, however, the jamming signal is beam formed. The jamming coverage, therefore, is limited to a sub-space of the surrounding environment. The physical secrecy of such approach is affected by the relative location of an eavesdropper to the terminals locations.

Concerning the physical-layer security in relaying scenarios, authors in [4] have studied two cases in the one-way relay scenarios: The two-hop full-duplex operation which is spectral resource saving oriented, and the time- division two-hop associated with jamming in which the physical secrecy is the primary concern. The latter case describes a time consecutive two-hop protocol, wherein in the first hop the relay node protects itself by sending a jamming signal that denies the eavesdropper from decoding the source concur-rently transmitted signal. In the second hop, the relay forwards the source signal to its destination node, whereas, the source node is acting as friendly jammer. The mechanism suffers from a discontinuation in the transmission as it relies on dividing the transmission into two consecutive time slots.

It's an object of the invention to provide an improved concept for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication.

In a first aspect the invention provides a radio frequency communication and jamming device configured for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication, the radio frequency communication and jamming device comprising:

an antenna arrangement having a transmission section for transmitting out-going signals and a receiving section for receiving incoming signals;

a receiver device configured for extracting an incoming information signal from the incoming signals received via the receiving section of the antenna arrangement in a receiving frequency band;

a jamming generator configured for generating at least one jamming signal for jamming at least one jamming frequency band, wherein the jamming signal is transmitted as one of the outgoing signals via the transmission section, wherein the at least one jamming frequency band includes the receiving fre-quency band; and

a self-interference cancellation device configured for cancelling portions of the at least one jamming signal in the incoming signals received via the receiving section at least in the receiving frequency band.

The term "radio frequency communication" refers to all kinds of communication, such as voice communication or data communication, via air waves. The term "information signal" refers to any meaningful signal. The term "physically secured" refers to that type of communication, which is secured by means at a physical layer of the respective radio frequency communication system. In particular, it refers to radio frequency communication systems in which meaningful transmissions are prevented from being received and decoded by a potential eavesdropper by jamming. Such communication systems provide secure communication without encryption, steganography or other known techniques for securing meaningful transmissions. The term "jamming" refers to actively transmitting radio waves which override the meaningful transmissions at a receiver of the potential eavesdropper.

Self-interference cancellation is a technology that cancels the "unwanted" energy that leaks into a receiver device of the communication device while the communication device is transmitting. As a result of the cancellation, the receiver receives significantly less or no noise from its transmitter, freeing it to cleanly receive external signals. A communication device using self-interference cancellation technology can transmit and receive at the same time on the same frequency. According to the invention, self-interference cancellation is used to enable the receiver device to extract the information signal in presence of the jamming signal, which will be explained in more details below.

Basically, the main idea behind the invention is to provide a distributed, multi-frequency-band jamming mechanism that disrupts (jams) the hostile communications over the jammed frequency bands, while enabling only the friendly devices to communicate over a physically secured (jammed) wireless medium among each other. Furthermore, the smart jamming mechanism also po-tentially allows eavesdropping on the attempted-to-establish hostile wireless communication links over the jammed bands. Each friendly radio frequency communication and jamming device, which is a part of the smart jamming mesh communication network, jams its surrounding space by transmitting whatever jamming signals over the jamming-targeted frequency bands. It could be multiple scattered bands, one continuous ultra-wide band or even a combination of both. By that, the communication among the hostile commu-

nication devices in the jamming coverage area is disrupted as their receivers shall be jammed by means of the transmitted jamming signals. The geographic jammed area is determined in accordance with the transmit power, the number and the location of the radio frequency communication and jam-ming devices distributed in the jamming network. The invented solution improves these ordinary jamming regimes by offering a method to secure the wireless links among the friendly radio frequency communication and jamming device while keeping the hostile communication devices jammed. This is done by taking advantage of the self-interference cancellation device which allows the friendly radio frequency communication and jamming devices to receive over at least one of the jammed frequency bands. In other words, the radio frequency communication and jamming devices in the mesh network may cooperate together to jam their surrounding space for the hostile communication devices and secure the communication among the friendly radio frequency communication and jamming devices.

The proposed mechanism of the system achieves three major goals:

1. Physically securing the wireless communication links among the

friendly radio frequency communication and jamming devices.

2. Jamming the wireless space at one or more frequency bands and, by that, disrupting the communication links among the hostile communication devices.

3. Potentially intercepting and eavesdropping on the attempted-to- transmit signals from the hostile communication devices.

The invention provides a highly secure wireless link among the friendly mesh network devices, while keeping the hostile devices jammed and hence unable to communicate among each other. The jamming as desired functionality is exploited to be as well a physical secrecy providing mechanism for the friendly communication links. In other words, the jamming signal is used as a covering signal to bury the communication links among the friendly radio fre-quency communication and jamming devices instead of being a disabler

(jammer) of friendly communication, while keeping its main purpose as hos-tile's communication disruption mechanism maintained in operation.

According to preferred embodiment of the invention the self-interference can-celiation device comprises an inserting device for inserting a self-interference cancelation signal into the incoming signals downstream of the receiving section and a self-interference cancelation signal calculating device for calculating the self-interference cancelation signal from the jamming signal. Such a self-interference cancellation approach is also known as self-interference cancellation by signal injection in the radio frequency domain. However, the self-interference cancellation device may be designed according to other se!f-cancellation approaches or a combination of these approaches, such as attenuating of the self-interference signal in the radio frequency domain, cancellation of the self-interference signal in the analog domain of the receiver device or cancellation of the self-interference signal in the digital domain of the receiver device.

The self-interference cancelation signal may be, for example, inserted into the incoming signals between of the receiving section and the receiver de-vice. In other embodiments, The self-interference cancelation signal may also be inserted into the incoming signals at the receiver device.

The self-interference cancellation device may be designed according to references [5] to [9], although the self-interference cancellation approaches of references [5] to [9] initially were intended for different applications.

According to preferred embodiment of the invention the radio frequency communication and jamming device further comprises:

a transmitter device configured for generating at least one outgoing information signal in a transmission frequency band, wherein the outgoing information signal is transmitted as one of the outgoing signals via the transmission section, wherein the transmission frequency band and the receiving frequency band do not overlap;

wherein the at least one jamming frequency band excludes the transmission frequency band.

These features allow the radio frequency communication and jamming device not only to receive physically secured incoming information signals but also to transmit outgoing information signals. These outgoing information signals then may be physically secured by the jamming generator of a further radio frequency communication a jamming device according to the invention. By these means a bidirectional physically secured communication may be creat-ed.

According to a preferred embodiment of the invention the transmission section comprises a first radiation pattern control unit configured for adapting a radiation pattern for transmitting the outgoing information signal. These fea-tures allow directing the outgoing information signal towards the friendly radio frequency communication and jamming device for which it is intended. One advantage of these features is that the physical security may be increased as the information signal covers limited transmission range - due to the fact that only potential eavesdroppers within the transmission range are able to re-ceive the outgoing information signal. The transmission range may be adapted in an azimuthal and/or elevational direction. Another advantage of these features is that the possible distance between the sending radio frequency communication and jamming device and the receiving radio frequency communication and jamming device may be increased without increasing the power of the outgoing information signal. Similarly, the power of the outgoing information signal may be decreased without decreasing the possible distance between the sending radio frequency communication and jamming device and the receiving radio frequency communication and jamming device.

According to a preferred embodiment of the invention the transmission section comprises a second radiation pattern control unit configured for adapting a radiation patterns for transmitting the respective jamming signal.

According to a preferred embodiment of the invention the transmission section comprises a power control unit configured for adapting a power of the jamming signal.

These features allow adapting the coverage of the jamming signal to positions of potential eavesdroppers so that the physical security may be increased.

According to a preferred embodiment of the invention the receiving section comprises a direction estimation unit configured for estimating a direction from which the incoming information signal is arriving.

According to a preferred embodiment of the invention the direction estimation unit is configured for adapting a receiving pattern for receiving the incoming information signal based on the estimated direction.

An advantage of these features is that the possible distance between the sending radio frequency communication and jamming device and the receiving radio frequency communication and jamming device may be increased without increasing the power of the incoming information signal. Similarly, the power of the incoming information signal may be decreased without decreasing the possible distance between the sending radio frequency communication and jamming device and the receiving radio frequency communication and jamming device. The radiation pattern may be adapted in an azimuthal and/or elevational direction.

According to a preferred embodiment of the invention the jamming generator is configured for generating a plurality of jamming signals of the jamming signals for jamming the at least one jamming frequency band, wherein the jam-ming signals of the plurality of jamming signals have different characteristics,

wherein the transmission section comprises a plurality of transmission channels, wherein each jamming signal of the plurality of jamming signals is transmitted over one transmission channel of the plurality of transmission channels, wherein the transmission channels of the plurality of transmission channels have different radiation patterns for transmitting the respective jamming signal.

These features improve the physical security of the friendly communication links in presence of smart hostile communication devices which are equipped with multi-antenna systems. Such smart hostiles are assumed to be capable of listening to the propagated signals from different directions discriminately.

These features of dividing the space into multiple sectors and jam each of the sectors using different jamming signal. In an exemplary implementation of the multi-sector enhanced smart jammers, the friendly radio frequency communication and jamming device divides the two-dimensional azimuthal space into four symmetric sectors and jams them with different signals. These features allow deceiving smart hostile communication devices that might have an ad-vanced technique to extract jamming signals and to cancel them. The reason for this is that the hostile communication device will most likely receive the jamming signal, which is intended for the sector in which the hostile communication device is located, and another jamming signal of the jamming signals, which is intended for other sector but reflected at natural or man-made obstacles so that it reaches the hostile communication device. Receiving two different jamming signals at the same time from different directions makes it almost impossible to cancel the respective jamming signals and hence extract the information signal.

According to a preferred embodiment of the invention the receiver device is configured for extracting the incoming information signal and a further incoming information signal from the incoming signals received via the receiving section, wherein the incoming signal is in the receiving frequency band, wherein the further incoming signal is in a further receiving frequency band, wherein the at least one jamming frequency band includes the further receiving frequency band;

wherein the transmitter device is configured for generating the outgoing information signal and a further outgoing information signal, wherein the further outgoing information signal is transmitted via the transmission section in a further transmission frequency band, which is not overlapping the frequency band of the outgoing information signal; and

wherein the further transmission frequency band and the further receiving frequency band do not overlap.

These features allow the radio frequency communication and jamming device to establish two independent physically secured bidirectional communication links with two further radio frequency communication and jamming devices.

According to preferred embodiment of the invention the receiving section is configured for receiving the incoming information signal and a further incoming information signal of the incoming signals, which are in the same receiving frequency band;

wherein the receiving section comprises a direction estimation unit configured for estimating a direction of origin for both of the incoming information signal and the further information signal;

wherein the receiver device is configured for extracting the incoming infor-mation signal and a further incoming information signal from the incoming signals received via the receiving section using the estimated directions of origin; and

wherein the transmitter device is configured for generating the outgoing in-formation signal and a further outgoing information signal, wherein the further outgoing information signal is transmitted via the transmission section in the transmission frequency band.

These features allow the radio frequency communication and jamming device to establish two independent physically secured bidirectional communication links with two further radio frequency communication and jamming devices within the same receiving frequency band.

In a further aspect the invention provides a system for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication, the system comprising:

a first radio frequency communication and jamming device according to one of the claims 3 to 9; and

a second radio frequency communication and jamming device according to one of the claims 3 to 9;

wherein the receiving frequency band of the first radio frequency communication and jamming device includes the transmission frequency band of the second radio frequency communication and jamming device;

wherein the receiving frequency band of the second radio frequency communication and jamming device includes the transmission frequency band of the first radio frequency communication and jamming device wherein the out-going information signal of the first radio frequency communication and jamming device is the incoming information signal of the second radio frequency communication and jamming device;

wherein the outgoing information signal of the first radio frequency communi-cation and jamming device is the incoming information signal of the second radio frequency communication and jamming device; and

wherein the outgoing information signal of the second radio frequency communication and jamming device is the incoming information signal of the first radio frequency communication and jamming device.

According to a preferred embodiment of the invention the system further comprises:

a third radio frequency communication and jamming device according to one of the claims 3 to 9;

wherein the second radio frequency communication and jamming device is configured according to claim 11

wherein the receiving frequency band of the third radio frequency communi- cation and jamming device includes the further transmission frequency band of the second radio frequency communication and jamming device;

wherein the further receiving frequency band of the second radio frequency communication and jamming device includes the transmission frequency band of the third radio frequency communication and jamming device;

wherein the first radio frequency communication and jamming device and the third radio frequency communication and jamming device are located in reach of the second radio frequency communication and jamming device;

wherein the first radio frequency communication and jamming device and the third radio frequency communication and jamming device are located mutually out of reach;

wherein the further outgoing information signal of the second radio frequency communication and jamming device is the incoming information signal of the third radio frequency communication and jamming device; and

wherein the outgoing information signal of the third radio frequency communication and jamming device is the further incoming information signal of the second radio frequency communication and jamming device.

According to a preferred embodiment of the invention the system further comprises:

a third radio frequency communication and jamming device according to one of the claims 3 to 9;

wherein the receiving frequency band of the third radio frequency communication and jamming device includes the transmission frequency band of the second radio frequency communication and jamming device;

wherein the receiving frequency band of the second radio frequency commu-nication and jamming device includes the transmission frequency band of the third radio frequency communication and jamming device;

wherein the first radio frequency communication and jamming device and the third radio frequency communication and jamming device are located in reach of the jamming device of the second radio frequency communication and jamming device;

wherein the first radio frequency communication and jamming device and the third radio frequency communication and jamming device are located mutually out of reach;

wherein the transmission frequency band of the first frequency communication and jamming device is equal to the transmission frequency band of the first frequency communication and jamming device;

wherein the second radio frequency communication and jamming device is configured according to claim 1 ;

wherein the further outgoing information signal of the second radio frequency communication and jamming device is the incoming information signal of the third radio frequency communication and jamming device; and

wherein the outgoing information signai of the third radio frequency communication and jamming device is the further incoming information signal of the second radio frequency communication and jamming device.

In a further aspect the invention provides a method for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication, the method comprising the steps:

transmitting outgoing signals by using a transmission section of an antenna arrangement and receiving incoming signals by using a receiving section of the antenna arrangement;

extracting an incoming information signal from the incoming signals received via the receiving section in a receiving frequency band by using a receiver device;

generating at least one jamming signal for jamming at least one jamming frequency band by using a jamming generator, wherein the jamming signal is transmitted as one of the outgoing signals via the transmission section, wherein the at least one jamming frequency band includes the receiving frequency band; and

cancelling portions of the at least one jamming signal in the incoming signals received via the receiving section at least in the receiving frequency band by using a self-interference cancellation device.

In a further aspect the invention provides a method for operating a system for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication, the system comprising:

a first radio frequency communication and jamming device according to one of the claims 3 to 11 ; and

a second radio frequency communication and jamming device (1.2) accord-ing to one of the claims 3 to 1 1 ;

wherein the method comprises the steps of:

setting the receiving frequency band of the first radio frequency communica-tion and jamming device and the transmission frequency band of the second radio frequency communication and jamming device in such way that the receiving frequency band of the first radio frequency communication and jamming device includes the transmission frequency band of the second radio frequency communication and jamming device; and

setting the receiving frequency band of the second radio frequency communication and jamming device and the transmission frequency band of the first radio frequency communication and jamming device in such way that the receiving frequency band of the second radio frequency communication and jamming device includes the transmission frequency band of the first radio frequency communication and jamming device;

using the outgoing information signal of the first radio frequency communication and jamming device as the incoming information signal of the second radio frequency communication and jamming device; and

using the outgoing information signal of the second radio frequency communication and jamming device as the incoming information signal of the first radio frequency communication and jamming device.

In a further aspect the invention provides a computer program for, when running on a processor, executing the method according to the invention.

Preferred embodiments of the invention are subsequently discussed with respect to the accompanying drawings, in which:

Fig. 1 illustrates a first embodiment of a radio frequency communication and jamming device according to the invention in a schematic view;

Fig. 2 illustrates functionalities of some embodiments of a radio frequency communication and jamming device according to the invention in an exemplary environment in a schematic view;

Fig. 3 illustrates a second embodiment of a radio frequency communication and jamming device according to the invention in a schematic view;

Fig. 4 illustrates functionalities of some embodiments of a radio frequency communication and jamming devices an exemplary system comprising two radio frequency communication and jamming devices according to the invention in an exemplary environment in a schematic view;

Fig. 5 illustrates a third embodiment of radio frequency communication and jamming device according to the invention in a schematic view;

illustrates functionalities of some embodiments of a radio frequency communication and jamming device according to the invention in an exemplary environment in a schematic view;

illustrates functionalities of some embodiments of a radio frequency communication and jamming device according to the invention in an exemplary environment in a schematic view;

illustrates functionalities of some embodiments of a radio frequency communication and jamming devices and an exemplary system comprising three radio frequency communication and jamming devices according to the invention in an exemplary environment in a schematic view; and

illustrates functionalities of some embodiments of a radio frequency communication and jamming devices and a further exemplary system comprising three radio frequency communication and jamming devices according to the invention in an exemplary environment in a schematic view.

Equal or equivalent elements or elements with equal or equivalent functionality are denoted in the following description by equal or equivalent reference numerals.

In the following description, a plurality of details is set forth to provide a more thorough explanation of embodiments of the present disclosure. However, it will be apparent to those skilled in the art that embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form rather than in detail in order to avoid obscuring embodiments of the present disclosure. In addition, features of the different embodiments described hereinafter may be combined with each other, unless specifically noted otherwise.

Fig. 1 illustrates a first embodiment of a radio frequency communication and jamming device 1 according to the invention in a schematic view. The radio

frequency communication and jamming device 1 is configured for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication. The radio frequency communication and jamming device 1 comprises:

an antenna arrangement 2, 3 having a transmission section 2 for transmitting outgoing signals OS and a receiving section 3 for receiving incoming signals IS;

a receiver device 4 configured for extracting an incoming information signal IIS from the incoming signals IS received via the receiving section 3 in a receiving frequency band R;

a jamming generator 5 configured for generating at least one jamming signal JS for jamming at least one jamming frequency band J, wherein the jamming signal JS is transmitted as one of the outgoing signals OS via the transmission section 2, wherein the at least one jamming frequency band J includes the receiving frequency band R; and

a self-interference cancellation device 6 configured for cancelling portions of the at least one jamming signal JS in the incoming signals IS received via the receiving section 3 at least in the receiving frequency band R.

The transmission section 2 comprises a transmission antenna set 7 which comprises one or more transmission antennas. The receiving section 3 comprises receiving antenna set 8 which comprises one or more receiving antennas.

According to a preferred embodiment of the invention the self-interference cancellation device 1 comprises an inserting device 9 for inserting a self-interference cancelation signal SICS into the incoming signals IS downstream of the receiving section 3 and a self-interference cancelation signal calculating device 10 for calculating the self-interference cancelation signal SICS from the jamming signal JS.

In another aspect the invention provides a method for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication, the method comprising the steps:

transmitting outgoing signals OS by using a transmission section 2 of an antenna arrangement 2, 3 and receiving incoming signals IS by using a receiving section 3 of the antenna arrangement 2, 3;

extracting an incoming information signal IIS from the incoming signals IS received via the receiving section 3 in a receiving frequency band by using a receiver device 4;

generating at least one jamming signal JS for jamming at least one jamming frequency band by using a jamming generator 5, wherein the jamming signal JS is transmitted as one of the outgoing signals OS via the transmission section 2, wherein the at least one jamming frequency band includes the receiving frequency band; and

cancelling portions of the at least one jamming signal JS in the incoming sig-nals IS received via the receiving section3 at least in the receiving frequency band by using a self-interference cancellation device 6.

In another aspect the invention provides a computer program for, when running on a processor, executing the method described above.

Fig. 2 illustrates functionalities of some embodiments of radio frequency communication and jamming devices 1.1 and 1.2 according to the invention in an exemplary environment in a schematic view.

Fig. 2 provides an illustration of the invented jamming mechanism which is shown in a homogenous and obstacle-free environment, wherein a unidirectional physically secured link between the friendly radio frequency communication and jamming device 1.1 and the friendly radio frequency communication and jamming device 1.2 is illustrated. The disruptions or even the poten-tial interceptions of the hostile data signals HDS between the hostile communication devices HCD1 , HCD2 and HCD3 are also shown. The radiation pat-

tern RPJ for the jamming signal is omni-directional in the embodiment of Fig.2.

Fig. 2 shows two friendly radio frequency communication and jamming de-vices 1.1 and 1.2, which belong to the same friendly mesh network, having established a unidirectional physically-secured wireless link, whereas the hostile communication devices HCD1 , HCD2 and HCD3 in their surrounding are jammed at jamming frequency band JB. The unidirectional link between two radio frequency communication and jamming devices 1.1 and 1.2 is physically secured by the jamming signal JS transmitted by the radio frequency communication and jamming device 1.2, which is also that the dedicated destination for the outgoing information signal OIS1 sent by the radio frequency communication and jamming device 1.1.

The radio frequency communication and jamming device 1.2 jams its surrounding environment by sending multi-band jamming signals JS covering the jamming frequency band JB, while its neighboring radio frequency communication and jamming device 1.1 transmits an outgoing information signal OIS1 in the transmission band FA, which lies within the jamming frequency band JB. Then the outgoing information signal OIS1 is received by the radio frequency communication and jamming device 1.2 as the incoming information signal IIS2. In fact, the jamming signal JS at the radio frequency communication and jamming device 1.2 can be treated as a self-interference signal. Therefore, it can be completely or partially cancelled by taking ad-vantage of a self-interference cancellation mechanism such as described in documents [5] to [9]. The receiving radio frequency communication and jamming device 1.2 cancels the jamming signal JS in the receiving band RA in order to be able to receive and to extract the incoming information signal IIS2 in the jammed environment. In this way, the receiving radio frequency com-munication and jamming device 1.2 is the only device capable of decoding the outgoing information signal OIS1 as it is the only device in the network which has a perfect knowledge of the jamming signal JS. This knowledge combined with the self-interference cancellation device 6 allows the receiving radio frequency communication and jamming device 1.2 to cancel the jam-ming signal JS within the receiving frequency band RA, and accordingly enables its receiver device 4 to receive the outgoing information signal OIS1 as the incoming information signal IIS 2 within jamming frequency band JB. For the hostile communication devices HCD1 , HCD2 and HCD3 the transmission frequency band FA along with the rest of jammed frequency band JB are disrupted frequencies, so that establishing or maintaining a communication over of jammed frequency band JB is not possible.

Finally, to summarize the results of the entire mechanism, the friendly transmitting node 1.1 sustains a unidirectional physically-secured wireless link to the friendly receiving node 1.2. The jammer node 1.2 operates as multi-frequency band jammer that prevents the hostile nodes HCD1 , HCD2 and HCD3 in its surrounding geographic area to exchange information over the jammed frequency wireless links and, furthermore, physically secures the friendly communication destined to it.

The explained example introduces the friendly jamming node 1.2 and the friendly source of communication 1.1 as two separate entities. However, in actual regimes they are combined in one joint entity. Thus, each of the friendly nodes 1.1 and 1.2 may be a multi-band jamming source, a source of meaningful transmission data links, and a destination for a meaningful trans-mission from its neigh boring node(s). By that, physically-secured bidirectional links between two adjacent nodes may be sustained over two different transmission frequency bands.

Fig. 3 illustrates a second embodiment of a radio frequency communication and jamming device 1 according to the invention in a schematic view. The second embodiment is based on the first embodiment so that the differences with respect to the first embodiment are explained.

According to a preferred embodiment of the invention the radio frequency communication and jamming device 1 further comprises:

a transmitter device 11 configured for generating at least one outgoing information signal OIS in a transmission frequency band F, wherein the outgoing information signal OIS is transmitted as one of the outgoing signals OS via the transmission section 2, wherein the transmission frequency band F and the receiving frequency band R do not overlap;

wherein the at least one jamming frequency band J excludes the transmission frequency band F.

Fig. 4 illustrates functionalities of some embodiments of a radio frequency communication and jamming devices 1.1 and 1.2 and an exemplary system comprising two radio frequency communication and jamming devices 1.1 and 1.2 according to the invention in an exemplary environment in a schematic view.

The system for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication comprises:

a first radio frequency communication and jamming device 1.1 being config-ured for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication, wherein the first radio frequency communication and jamming device 1.1 comprises: an antenna arrangement 2, 3 having a transmission section 2 for transmitting outgoing signals OS and a receiving section 3 for receiving incoming signals IS, a receiv-er device 4 configured for extracting an incoming information signal IIS1.1 from the incoming signals IS received via the receiving section 3 in a receiving frequency band RB, a jamming generator 5 configured for generating at least one jamming signal JS1 for jamming at least one jamming frequency band JA, wherein the jamming signal JS1 is transmitted as one of the out-going signals OS via the transmission section 2, wherein the at least one jamming frequency band JA includes the receiving frequency band RB, a self-interference cancellation device 6 configured for cancelling portions of the at least one jamming signal JS1 in the incoming signals IS received via the receiving section 3 at least in the receiving frequency band RB, and a transmitter device 11 configured for generating at least one outgoing information signal OIS1.1 in a transmission frequency band FA, wherein the outgoing information signal OIS1.1 is transmitted as one of the outgoing signals OS via the transmission section 2, wherein the transmission frequency band FA and the receiving frequency band RB do not overlap, wherein the at least one jamming frequency band JA excludes the transmission frequency band FA;

and

a second radio frequency communication and jamming device 1.2 being con-figured for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication, wherein the second radio frequency communication and jamming device 1.2 comprises: an antenna arrangement 2, 3 having a transmission section 2 for transmitting outgoing signals OS and a receiving section 3 for receiving incoming signals IS, a re-ceiver device 4 configured for extracting an incoming information signal IIS2.1 from the incoming signals IS received via the receiving section 3 in a receiving frequency band RA, a jamming generator 5 configured for generating at least one jamming signal JS2 for jamming at least one jamming frequency band JB, wherein the jamming signal JS2 is transmitted as one of the outgoing signals OS via the transmission section 2, wherein the at least one jamming frequency band JB includes the receiving frequency band RA, a self-interference cancellation device 6 configured for cancelling portions of the at least one jamming signal JS2 in the incoming signals IS received via the receiving section 3 at least in the receiving frequency band RA, and a transmitter device 11 configured for generating at least one outgoing information signal OIS2.1 in a transmission frequency band FB, wherein the outgoing information signal OIS2.1 is transmitted as one of the outgoing signals OS via the transmission section 2, wherein the transmission frequency band FB and the receiving frequency band RA do not overlap, wherein the at least one jamming frequency band JB excludes the transmission frequency band FB;

wherein the receiving frequency band RB of the first radio frequency communication and jamming device 1.1 includes the transmission frequency band FB of the second radio frequency communication and jamming device 1.2; and

wherein the receiving frequency band RA of the second radio frequency communication and jamming device 1.2 includes the transmission frequency band FA of the first radio frequency communication and jamming device 1.1 ; wherein the outgoing information signal OIS1.1 of the first radio frequency communication and jamming device 1.1 is the incoming information signal IIS2.1 of the second radio frequency communication and jamming device 1.2; and

wherein the outgoing information signal OIS2.1 of the second radio frequency communication and jamming device 1.2 is the incoming information signal I IS 1.1 of the first radio frequency communication and jamming device 1.1.

Fig. 4 illustrates the mechanism considering a scenario comprising two friendly nodes 1.1 and 1.2 being capable of jamming. Recall from the formerly elaborated example, each node 1.1 and 1.2 may act as a multiband jammer except for the transmitting band FA (for node 1.1 ) or FB (for node 1.2) in order to avoid jamming the destination node 1.1 or 1.2. The transmitting bands FA of node 1.1 is kept jammed by the jamming signal JS2 as the transmitting band FA of node 1.1 is included in the jamming band JB of note 1.2 and the transmitting band FB off node 1.2 is kept jammed (physically-secured) by the jamming signal JS1 as the transmitting band FB off node 1.2 is included in the jamming band J A of node 1.1. A bidirectional secure wire-less link is maintained between the friendly node 1.1 and the friendly node 1.2 over the transmission frequency bands FA and FB, respectively. The node 1.1 jams a subset JA whereas the node 1.2 jams a complement subset JB so that the overall jammed frequency band is JA u JB, wherein FA £ JA, FB e JA and wherein FB e JB, FB £ JB.

Another functionally of the invention is the possibility of intercepting the hostile attempt-to-establish links. This can be done in a similar manner as it is accomplished for the physical secrecy of the friendly links. In other words, the friendly jamming nodes 1.1 and 1.2 suppress their jamming (self-interference) signals over the hostile communication frequency bands Thereby they would be able to eavesdrop on the hostile communications.

In a further aspect the invention provides a method for operating a system for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication, the system comprising:

a first radio frequency communication and jamming device 1.1 according to one of the claims 3 to 11 ; and

a second radio frequency communication and jamming device 1.2 according to one of the claims 3 to 1 ;

wherein the method comprises the steps of:

setting the receiving frequency band RB of the first radio frequency commu-nication and jamming device 1.1 and the transmission frequency band FB of the second radio frequency communication and jamming device 1.2 in such way that the receiving frequency band RB of the first radio frequency communication and jamming device 1.1 includes the transmission frequency band FB of the second radio frequency communication and jamming device 1.2; and

setting the receiving frequency band RA of the second radio frequency communication and jamming device 1.2 and the transmission frequency band FA of the first radio frequency communication and jamming device 1.1 in such way that the receiving frequency band RA of the second radio frequency communication and jamming device 1.2 includes the transmission frequency band FA of the first radio frequency communication and jamming device 1.1 ;

using the outgoing information signal OIS1.1 of the first radio frequency communication and jamming device 1.1 as the incoming information signal IIS2.1 of the second radio frequency communication and jamming device 1.2; and

using the outgoing information signal OIS2.1 of the second radio frequency communication and jamming device 1.2 as the incoming information signal US 1.1 of the first radio frequency communication and jamming device 1.1.

Fig. 5 illustrates a third embodiment of radio frequency communication and jamming device 1 according to the invention in a schematic view.

According to a preferred embodiment of the invention the transmission section 2 comprises a first radiation pattern control unit 13 configured for adapting a radiation pattern RPO for transmitting the outgoing information signal OIS.

According to a preferred embodiment of the invention the transmission section 2 comprises a second radiation pattern control unit 14 configured for adapting a radiation pattern RPJ for transmitting the jamming signal JS.

According to a preferred embodiment of the invention the transmission section 2 comprises a power control unit (not shown) configured for adapting a power of the jamming signal JS.

According to a preferred embodiment of the invention the receiving section 3 comprises a direction estimation unit 15 configured for estimating a direction from which the incoming information signal IIS is arriving.

According to preferred embodiment of the invention the direction estimation unit 15 is configured for adapting a receiving pattern for receiving the incoming information signal IIS based on the estimated direction.

Fig. 6 illustrates functionalities of some embodiments of radio frequency communication and jamming devices 1.1 and 1.2 according to the invention in an exemplary environment in a schematic view. The radiation pattern RPO1 for transmitting the outgoing information signal OIS1 of friendly node 1.1 is adapted in such way that the transmission beam RPO1 is fully overlapped by the jamming radiation pattern RPJ2 of friendly node 1.2. As a result, hostile communication device H CD4 is not capable of receiving the outgoing information signal OIS1 although it is located outside of the jamming radiation pattern RPJ2. Hence, with the aid of pattern-forming techniques (beam-forming techniques) the physically-security of the wireless communication links can be augmented in order to meet higher risk scenarios that might be encounter in real-world implementations. Some sort of combination of both techniques, i.e., the increment of the jamming power and beamform-ing, could be also used based on the required security standards.

The transmission beam RP01 can be adaptively steered to maintain its up-to-date directivity toward its desirable destination. This would be especially useful in the moving node scenarios, such as moving convoys. Basically, the entire smart jamming system must keep the information signal transmission coverage RP01 as much as possible overlapped with the jamming covered area RPJ2 by the other friendly nodes. Therefore, the invented jamming system would benefit from being always aware of its surrounding environment and the status of the active friendly nodes in the jammed or physically-secured network.

Fig. 7 illustrates functionalities of some embodiments of radio frequency communication and jamming devices 1.1 and 1.2 according to the invention in an exemplary environment in a schematic view.

According to preferred embodiment of the invention the jamming generator 5 is configured for generating a plurality of jamming signals JS2.1 , JS2.2, JS2.3, JS2.4 of the jamming signals JS for jamming the at least one jamming frequency band J, wherein of jamming signals JS2.1 , JS2.2, JS2.3, JS2.4 of the plurality of jamming signalsJS2.1 , JS2.2, JS2.3, JS2.4 have different characteristics,

wherein the transmission section 2 comprises a plurality of transmission channels, wherein each jamming signal JS2.1 , JS2.2, JS2.3, JS2.4 of the plurality of jamming signals JS2.1 , JS2.2, JS2.3, JS2.4 is transmitted over one transmission channel of the plurality of transmission channels, wherein the transmission channels of the plurality of transmission channels have different radiation patterns RPJ2.1 , RPJ2.2, RPJ2.3, RPJ2.4 for transmitting the respective jamming signal JS2.1 , JS2.2, JS2.3, JS2.4.

In a scenario, where a hostile node which is equipped with a multi-antenna system, is trying to eavesdrop on the friendly physically-secured links, the hostile node might employ its multiple antenna system to capture only the jamming signal by sectorizing the space and by listening to a signal from an angularly narrowed direction. Fig. 7 shows an example of a hostile node HCD1 equipped with an antenna system that is capable of separating (sectorizing) the space angularly to four sectors. The hostile node HCD1 may isolate an estimation of the jamming signal JS2.1 by capturing only the direct incident wave from the friendly radio frequency communication and jamming device 1.2 without capturing the meaningful transmission signal OIS1 from the friendly radio frequency communication and jamming device 1.1. This knowledge of the jamming signal JS2.1 could then be utilized at the hostile communication device HCD1 to cancel out the jamming signal JS2.1 from a combination of the jamming signal JSP2.1 and the meaningful transmission signal OIS1 being estimated by means of different antenna(s) in order to obtain the meaningful transmission signal OIS1.

However, the use of a plurality of jamming signals JS2.1 , JS2.2, JS2.3, JS2.4 of the jamming signals JS prevents such a derivation of the outgoing information signal OIS1. The multi-sector friendly jammer 1.2, as shown in Fig. 6, transmits four different jamming signals JS2.1 , JS2.2, JS2.3, JS2.4 oriented into four different directions. The entire surrounding space is accordingly jammed and virtually divided into four jammed sectors. Four jamming sectors are considered for giving an example, however, any number of sectors can be considered for the jamming system without any upper boundary limitations.

The hostile listener HCD1 may try to obtain a separated estimation of the jamming signal JS2.1. Another simultaneous reception is assumed to be made by the hostile listener HCD1 to capture a signal that contains the jamming signal JS2.1 and the friendly outgoing information signal OIS1 in com-bination. Then, the hostile listener HCD1 may try to utilize the knowledge of the jamming signal JS2.1 to filter out the jamming signal JS2.1 from the combined signal. This method would be effective considering an omni-directional friendly jammer in which the jamming signal JS2.1 is the same for each captured signai by the hostile eavesdropper.

However, having the friendly jammer 1.2 sending multiple jamming signals JS2.1 , JS2.2, JS2.3, JS2.4 to different spatial location may deny the hostile eavesdropper from extracting the meaningful information signal OIS1 as the assumed signals captured by hostile listener HCD1 would be containing two different jamming signals JS2.1 and JS2.4, wherein the jamming signal JS2.1 is a jamming signal JS2.1 , which is designated for the sector in which the hostile listener HCD1 is located, and wherein the jamming signal JS2.4 is a jamming signal JS2.4, which is designated for a sector in which the hostile listener HCD1 is not located and which is received by the hostile listener HCDI after a reflection at an obstacle OBS. The hostile iistener HCD1 cannot use the knowledge of the jamming signal JS2.1 from the first estimation to subtract (cancel) it from the combined captured estimation. The friendly jammers 1.2 could also rotate or interchange these beam-formed patterns in order to make it even harder for the smart hostile Iistener HCD1 to determine (isolate) the source of the jamming signal or to cancel the jamming signals.

The case where a friendly omni-directional jammer 1.2 is used, the signal SFS received in a first sector of the sectors of the hostile Iistener HCD1 can be expressed b


and the signal SSS received in a second sector of the sectors of the hostile Iistener HCD1 can be given by

yi¾( = ¾( » V) + sd( - + "( , (2) where n(t) is the additive white Gaussian noise term caused by the thermal noise of the receiving node HCD1 , wherein. sj(t) is the jamming signal JS2.1 and wherein sd(t) is the meaningful signal OIS1 transmitted by the friendly node 1.1.

Equations 1 and 2 show the case where the system uses an omnidirectional jamming approach. The hostile node can invoke a cross-correlation function between these equations in order to cancel the jamming signal.

However, in the case of multi-sector jamming approach which is shown in Fig. 7, the signal SFS received in a first sector of the sectors of the hostile Iistener HCD1 can be expressed by

.VH!(') = S|, ( « 0 "(0- (3) and the signal SSS received in a second sector of the sectors of the hostile Iistener HCD1 can be given by

wherein sj1 (t) is the jamming signal JS2.1 and wherein si2(t) is the jamming signal JS2.2 which is different from the jamming signal JS2.1.

Equations 3 and 4 indicate the improvement in security measures as the hostile node HCD1 is not able to invoke the cross-correlation function between these two Equations as Equation 4 has a new additive term, sj2(t) - hj4(t), which is not correlated to any term at Equation 3.

Fig. 8 illustrates functionalities of some embodiments of radio frequency communication and jamming devices 1 .1 , 1 .2 and 1 .3 and an exemplary system comprising three radio frequency communication and jamming devices 1.1 , 1.2 and 1.3 according to the invention in an exemplary environment in a schematic view.

In the following a scenario of three radio frequency communication and jamming devices 1.1 , 1.2 and 1.3 is assumed. The radio frequency communication and jamming devices 1 .1 , 1.2 and 1.3 may for instance be carried by vehicles, which are either stationary or on the move distanced apart from each other. These vehicles want to exchange information over a secured wireless medium, whereas, denying any hostile device HCD1 , HCD2 and HCD3 in their surrounding geographic area to establish or exchange data over the wireless medium. The wireless medium will be jammed by means of a multi-source (distributed) jamming points, i.e., each of the vehicles transmits a jamming signal to jam its surrounding space. Having many distributed jamming devices 1 .1 , 1 .2 and 1 .3 increases the covered jammed area. All the hostile communication links HDS within the jammed space will be disrupted, therefore, the hostile devices HCD1 , HCD2 and HCD3 won't be able to communicate over the jammed frequency bands J. However, this system would be different from the ordinary (currently-used) jamming mechanism in which the friendly devices 1.1 , 1.2 and 1.3 cannot exchange between them as the wireless medium was jammed by themselves. The invented techniques allow the vehicles to maintain physically-secured wireless links over the jammed medium. The technique basically relies on the self-interference cancellation capability where each of the jamming nodes 1.1 , 1.2 and 1.3 suppresses its own jamming signal JS1 , JS2 and JS3 locally - based on the perfect knowledge of the respective jamming signal JS1 , JS2 and JS3 at the jammer itself - at one of jammed frequency bands. This unlocks this frequency band to a neighbor friendly node 1.1 , 1.2 and 1.3 to transmit over this band. In this way, the communication can be secured by means of the jamming signal JS1 , JS2 and JS3 from the destination devicel .1 , 1.2 and 1.3, which is the only node 1.1 , .2 and 1.3 that may decode the incoming meaningful signal IIS1 , IIS2, IIS3 as it is the only device 1.1 , 1.2 and 1.3 that can cancel its jamming signal JS1 , JS2 and JS3. All hostile devices HCD1 , HCD2 and HCD3 would not be able to decode the meaningful transmission signals IIS1 , IIS2, IIS3 as they are not able to recover the jamming signals JS1 , JS2 and JS3. It has to be noted that the transmitter in multi-band jamming operation does not jam its own meaningful transmission frequency band FA, FB, FC and relies for its own is transmission frequency band FA, FB, FC on the jamming capability of the receiver node 1.1 , 1.2 and 1.3 (destination node) and perhaps the other friendly jammers .1 , 1.2 and 1.3, while it continues in jamming the rest of the jamming-targeted bands. The given example was explained considering a scenario of three vehicles, however, the implementation is not restricted to vehicles or the count of three, it could be any kind of wireless devices to whatever count of them is required to be part of the friendly physically-secured network.

The radio frequency communication and jamming device 1.2 is configured according to a preferred embodiment of the invention. The receiver device 4 of the radiofrequency communication and jamming device 1.2 is configured for extracting the incoming information signal IIS2.1 and a further incoming information signal IIS2.2 from the incoming signals IS received via the receiving section 3, wherein the incoming signal IIS2.1 is in the receiving frequency band RA, wherein the further incoming signal IIS2.2 is in a further receiving frequency band RC, wherein the at least one jamming frequency band JB includes the further receiving frequency band RC;

wherein the transmitter device 11 is configured for generating the outgoing information signal OIS2.1 and a further outgoing information signal OIS2.2, wherein the further outgoing information signal OIS2.2 is transmitted via the transmission section 2 in a further transmission frequency band FD, which is

not overlapping the frequency band FB of the outgoing information signal OIS2.1 ; and

wherein the further transmission frequency band FD and the further receiving frequency RC band do not overlap.

According to a preferred embodiment of the invention the system further comprises:

a third radio frequency communication and jamming device 1.3 being configured for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication, wherein the third radio frequency communication and jamming device 1.3 comprises: an antenna arrangement 2, 3 having a transmission section 2 for transmitting outgoing sig-nals OS and a receiving section 3 for receiving incoming signals IS, a receiver device 4 configured for extracting an incoming information signal IIS3.1 from the incoming signals IS received via the receiving section 3 in a receiving frequency band RD, a jamming generator 5 configured for generating at least one jamming signal JS3 for jamming at least one jamming frequency band JC, wherein the jamming signal JS3 is transmitted as one of the outgoing signals OS via the transmission section 2, wherein the at least one jamming frequency band JC includes the receiving frequency band RD, a self-interference cancellation device 6 configured for cancelling portions of the at least one jamming signal JS3 in the incoming signals IS received via the receiving section 3 at least in the receiving frequency band RD, and a transmitter device 11 configured for generating at least one outgoing information signal OIS3.1 in a transmission frequency band FC, wherein the outgoing information signal OIS3.1 is transmitted as one of the outgoing signals OS via the transmission section 2, wherein the transmission frequency band FC and the receiving frequency band RD do not overlap, wherein the at least one jamming frequency band JC excludes the transmission frequency band FC;

wherein the second radio frequency communication and jamming device 1.2 comprises the features that the receiver device 4 is configured for extracting the incoming information signal IIS2.1 and a further incoming information sig- nal I1S2.2 from the incoming signals IS received via the receiving section 3, wherein the incoming signal IIS2.1 is in the receiving frequency band RA, wherein the further incoming signal IIS2.2 is in a further receiving frequency band RC, wherein the at least one jamming frequency band JB includes the further receiving frequency band RC, wherein the transmitter device 1 1 is configured for generating the outgoing information signal OIS2.1 and a further outgoing information signal OIS2.2, wherein the further outgoing information signal OIS2.2 is transmitted via the transmission section 2 in a further transmission frequency band FD, which is not overlapping the frequency band FB of the outgoing information signal OIS2.1 , wherein the further transmission frequency band FD and the further receiving frequency RC band do not overlap;

wherein the receiving frequency band RD of the third radio frequency com-munication and jamming device 1.3 includes the further transmission frequency band FD of the second radio frequency communication and jamming device 1 .2;

wherein the further receiving frequency band RC of the second radio fre-quency communication and jamming device 1.2 includes the transmission frequency band FC of the third radio frequency communication and jamming device .3;

wherein the first radio frequency communication and jamming device 1.1 and the third radio frequency communication and jamming device .3 are located in reach of the second radio frequency communication and jamming device 1 .2;

wherein the first radio frequency communication and jamming device 1.1 and the third radio frequency communication and jamming device 1 .3 are located mutually out of reach;

wherein the further outgoing information signal OIS2.2 of the second radio frequency communication and jamming device 1 .2 is the incoming infor-mation signal IIS3.1 of the third radio frequency communication and jamming device 1.3; and

wherein the outgoing information signal OIS3.1 of the third radio frequency communication and jamming device 1.3 is the further incoming information signal IIS2.2 of the second radio frequency communication and jamming de-vice 1.2.

Each middle node 1.2 (not the edge nodes 1.1 and 1.3) requires three frequency bands in order to connect bidirectionally to its neighboring friendly nodesl .1 , 1.2, 1.3. The middle node 1.2 in this case does not require any directional of arrival (DOA) functionality to split the neighbor's connection links.

Fig. 9 illustrates functionalities of some embodiments of radio frequency communication and jamming devices 1.1 , 1.2 and 1.3 and a further exempla-ry system comprising three radio frequency communication and jamming devices 1.1 , 1.2 and 1.3 according to the invention in an exemplary environment in a schematic view.

The radio frequency communication and jamming device 1.2 of the radiofre-quency communication and jamming device 1.2 is configured according to a preferred embodiment of the invention. The receiving section 3 is configured for receiving the incoming information signal IIS2.1 and a further incoming information signal IIS2.2 of the incoming information signals IS, which are in the same receiving frequency band RA;

wherein the receiving section 3 comprises a direction estimation unit 15 configured for estimating a direction of origin for both of the incoming information signal IIS2.1 and the further information signal;

wherein the receiver device 4 is configured for extracting the incoming information signal IIS2.1 and a further incoming information signal IIS2.2 from the incoming signals IS received via the receiving section 3 using the estimated directions of origin; and

wherein the transmitter device 11 is configured for generating the outgoing information signal OIS2.1 and a further outgoing information signal OIS2.2, wherein the further outgoing information signal OIS2.2 is transmitted via the transmission section 2 in the transmission frequency band FB.

According to a preferred embodiment of the invention the system further comprises:

a third radio frequency communication and jamming device 1.3 being configured for physically secured friendly radio frequency communication and for jamming hostile radio frequency communication, wherein the third radio fre-quency communication and jamming device 1.3 comprises: an antenna arrangement 2, 3 having a transmission section 2 for transmitting outgoing signals OS and a receiving section 3 for receiving incoming signals IS, a receiver device 4 configured for extracting an incoming information signal IIS3.1 from the incoming signals IS received via the receiving section 3 in a receiv-ing frequency band RB, a jamming generator 5 configured for generating at least one jamming signal JS3 for jamming at least one jamming frequency band JA, wherein the jamming signal JS3 is transmitted as one of the outgoing signals OS via the transmission section 2, wherein the at least one jamming frequency band JA includes the receiving frequency band RB, a self-interference cancellation device 6 configured for cancelling portions of the at least one jamming signal JS3 in the incoming signals IS received via the receiving section 3 at least in the receiving frequency band RB, and a transmitter device 11 configured for generating at least one outgoing information signal OIS3.1 in a transmission frequency band FA, wherein the out-going information signal OIS3.1 is transmitted as one of the outgoing signals OS via the transmission section 2, wherein the transmission frequency band FA and the receiving frequency band RB do not overlap, wherein the at least one jamming frequency band JA excludes the transmission frequency band FB;

wherein the receiving frequency band RB of the third radio frequency communication and jamming device 1.3 includes the transmission frequency band FB of the second radio frequency communication and jamming device 1.2;

wherein the receiving frequency band RA of the second radio frequency

communication and jamming device 1.2 includes the transmission frequency band FA of the third radio frequency communication and jamming device 1.3;

wherein the first radio frequency communication and jamming device 1.1 and the third radio frequency communication and jamming device 1.3 are located in reach of the second radio frequency communication and jamming device 1.2;

wherein the first radio frequency communication and jamming device 1.1 and the third radio frequency communication and jamming device 1.3 are located mutually out of reach;

wherein the transmission frequency band FA of the first frequency communication and jamming device 1.1 is equal to the transmission frequency band FA of the first frequency communication and jamming device 1.1 ;

wherein the second radio frequency communication and jamming device 1.2 comprises the features that the receiving section 3 is configured for receiving the incoming information signal IIS2.1 and a further incoming information sig-nal IIS2.2 of the incoming information signals IS, which are in the same receiving frequency band RA, wherein the receiving section 3 comprises a direction estimation unit 15 configured for estimating a direction of origin for both of the incoming information signal IIS2.1 and the further information signal, wherein the receiver device 4 is configured for extracting the incoming information signal IIS2.1 and a further incoming information signal IIS2.2 from the incoming signals IS received via the receiving section 3 using the estimated directions of origin, and wherein the transmitter device 1 is configured for generating the outgoing information signal OIS2.1 and a further outgoing information signal OIS2.2, wherein the further outgoing information signal OIS2.2 is transmitted via the transmission section 2 in the transmission frequency band FB;

wherein the further outgoing information signal OIS2.2 of the second radio frequency communication and jamming device 1.2 is the incoming infor-mation signal IIS3.1 of the third radio frequency communication and jamming device 1.3; and

wherein the outgoing information signal OIS3.1 of the third radio frequency communication and jamming device 1.3 is the further incoming information signal IIS2.2 of the second radio frequency communication and jamming de-vice 1 .2.

In the example of Fig. 9 the middle node 1.2 can distinguish the direction of arrival (DOA) of multiple simultaneous signals. Hence, both neighboring nodes .1 and 1.3 can use the same transmission frequency bands FA.

Thus, the number of the required frequency bands FA, FB could be reduced to two instead of three. One benefit of such band reusing feature in terms of security is that the less number of bands is required for meaningful information signals transmission, the more bands can be jointly jammed by devices themselves. Accordingly, this means an overall enhancement on the secu-rity standards of the system.

Although some aspects have been described in the context of an apparatus, it is clear that these aspects also represent a description of the corresponding method, where a block or device corresponds to a method step or a fea-ture of a method step. Analogously, aspects described in the context of a method step also represent a description of a corresponding block or item or feature of a corresponding apparatus.

Reference signs:

1 radio frequency communication and jamming device

2 transmission section of the antenna arrangement

3 receiving section of the antenna arrangement

4 receiver device

5 jamming generator

6 self-interference cancellation device

7 transmitting antenna set

8 receiving antenna set

9 inserting device

10 self-interference cancelation signal calculating device

1 1 transmitter device

12 meaningful data source

13 first radiation pattern control unit

14 second radiation pattern control unit

15 direction estimation unit

OS outgoing signals

IS incoming signals

IIS incoming information signal

R receiving frequency band

JS jamming signal

J jamming frequency band

SICS self-interference cancellation signal

OIS outgoing information signal

F transmission frequency band

MDS meaningful data signal

ACS antenna control signal

HCD hostile communication device

HDS hostile data signal

RPJ radiation pattern for the jamming signal

RPO radiation pattern for transmitting the outgoing information signal

SFS signal received in a first sector

SSS signal received in a second sector

OBS obstacle

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WO 2017/008851 A1