Communication device and method for secure communication

Abstract

A first communication device for communicating with a second communication device in a wireless communication system includes a circuit configured to send a detection signal to multiple directions, receive an echo signal in response to the sent detection signal, and determine the location of a potential eavesdropping communication device based on the received echo signal.

Description

Technical Field

[0001] The present disclosure relates to a first communication device and method for communicating with a second communication device in a secure manner in a wireless communication system. Background Art

[0002] Secure information transmission between the sender and the intended recipient is one of the fundamental challenges in communication systems. In order to prevent information from being passed to unintended recipients (adversaries or eavesdropping devices), care must be taken to control the environment and / or protect the information with cryptography so that only the intended recipient can understand the transmitted information. Cryptographic methods usually operate at the upper layer of the transmission protocol. Once the signal is intercepted at a lower layer, such as the PHY layer (through a medium such as RF waves), brute force decryption is possible, especially when the packet length and encryption key are relatively short. This is especially true for Internet of Things (IoT) applications, where typically only a few bits or bytes are transmitted. Therefore, PHY layer security is considered an additional means to protect signals already at the PHY layer.

[0003] In a wireless communication system, all participants (hereinafter also referred to as communication devices) share the same communication medium and are able to listen to (or eavesdrop on) any communication within the reception range. According to traditional methods, information that should not be shared with all potential recipients may be encrypted using keys unique to the sender and the recipient. One way to establish these keys is to derive them from a pre-shared secret (also referred to as a network password) and grant them to legitimate participants associated with the network. Unless further measures are taken, all participants will thereafter be able to decrypt information from any other participant that is part of the network. In order to mitigate the potential "eavesdropping" problem of sensitive information, there is a concept of point-to-point encryption for such networks. However, in order to establish a secure communication link, encryption keys need to be exchanged. A general solution is implemented in the Extensible Authentication Protocol (EAP), which is used for key exchange in IEEE802.11 standard wireless LANs. The handshake process that occurs during the establishment phase of such a secure connection is still sensitive, and if it is eavesdropped, all subsequent communications may be decrypted and captured by potential eavesdropping devices.

[0004] The "background" description provided here is to generally present the context of the present disclosure. The work of the presently named inventors, to the extent described in the background section, and other aspects of the description that may not qualify as prior art at the time of filing, is neither explicitly nor implicitly admitted to be prior art against the present invention. Summary of the invention

[0005] The object is to provide a communication device capable of detecting the presence of a potential eavesdropping device. A further object of one embodiment is to use this information to prevent or at least make it more difficult for a potential eavesdropping device to actually eavesdrop on the communication between the first communication device and the second communication device. A further object is to provide a corresponding communication method and a corresponding computer program for implementing the communication method and a non-transitory computer-readable recording medium.

[0006] According to one aspect, a first communication device for communicating with a second communication device in a wireless communication system is provided, the first communication device comprising a circuit, the circuit being configured to:

[0007] Send out detection signals in multiple directions.

[0008] receiving an echo signal in response to the transmitted detection signal, and

[0009] The location of a potential eavesdropping communication device is determined from the received echo signals.

[0010] According to another aspect, a first communication method of a first communication device for communicating with a second communication device in a wireless communication system is provided, the first communication method comprising:

[0011] Send out detection signals in multiple directions.

[0012] receiving an echo signal in response to the transmitted detection signal,

[0013] The location of a potential eavesdropping communication device is determined from the received echo signals.

[0014] According to a further aspect, there is provided a computer program comprising program means for causing a computer to perform the steps of the method disclosed herein when the computer program is executed on a computer, and a non-transitory computer-readable recording medium in which a computer program product is stored, which program product, when executed by a processor, causes the method of the present disclosure to be performed.

[0015] Embodiments are defined in the dependent claims. It is to be understood that the disclosed communication method, the disclosed computer program and the disclosed computer readable recording medium have further embodiments similar and / or identical to the claimed communication device and as defined in the dependent claims and / or disclosed herein.

[0016] Compared to wired networks, in which all network participants are (quasi) statically connected to the medium, wireless communication systems broadcast their information to all objects within a certain range, depending on the propagation characteristics of the underlying radio frequency. In order to alleviate this situation, wireless communication networks provide the option of exploiting spatial properties, such as directivity, especially for higher frequencies. In addition, the wireless medium and its characteristics depend on multiple parameters, such as the location and orientation of the devices, time, etc. According to an embodiment of the present disclosure, one or more of these properties are used to improve the security of the information exchange between the first and second communication devices, thereby reducing the probability of eavesdropping by a third communication device (i.e., a potential eavesdropping device) in wireless communication systems (such as wireless local area networks), especially in the 60 GHz (or millimeter wave) spectrum, or in similar spectrums, such as 28 GHz for 5G cellular communications.

[0017] For this purpose, the position of the potential eavesdropping device is determined by evaluating the echo received in response to the transmission of the detection signal. In addition, in some embodiments, the corresponding evaluation can be performed by the second communication device (communication partner). This is not strictly required, because the communication partner usually cooperates with the first communication device in the beam training phase, so the direction of the second communication device relative to the first communication device is known. In one embodiment, based on the position information of the potential eavesdropping device, the transmission of the required message can be controlled, with the purpose of enabling the second communication device rather than the potential eavesdropping device to receive the desired message. In one embodiment, additionally or alternatively, artificial noise (also referred to as interference signal) can be sent to locally interfere with the potential eavesdropping device, that is, the transmission of artificial noise can be controlled so that the potential eavesdropping device receives the message and the artificial noise, thereby being unable to decode the message, while the second communication device can still successfully receive and decode the message. In this way, the probability that the third communication device (potential eavesdropping device) can eavesdrop on the communication between the first communication device and the second communication device is greatly reduced or even minimized.

[0018] It should be noted that determining the position of a device in the context of the present disclosure should be understood as at least determining the orientation of a device (e.g., a second communication device or a potential eavesdropping device) relative to another device (e.g., a first communication device). It is not required to determine the (precise) two-dimensional or three-dimensional (absolute or relative) position of the device.

[0019] The above paragraphs are provided by way of general introduction and are not intended to limit the scope of the following claims.The described embodiments, together with further advantages, may best be understood by reference to the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] A more complete understanding of the present disclosure, together with its many attendant advantages, will be readily obtained by referring to the following detailed description when considered in conjunction with the accompanying drawings, wherein:

[0021] Figure 1 A graph illustrating the confidentiality ratio as a function of the SNR of the receiving device and the SNR of the eavesdropping device is shown.

[0022] Figure 2 A graph illustrating the coded modulation secrecy ratio for 4-QAM modulation for different values ​​of the receiving device SNR and the eavesdropping device is shown.

[0023] Figure 3 A graph illustrating the coded modulation secrecy ratio of coupled systems with different attenuation factors and different modulation schemes is shown.

[0024] Figure 4A and Figure 4B A diagram illustrating an implementation for increasing messaging security according to the present disclosure is shown.

[0025] Figure 5 A schematic diagram of a communication system according to the present disclosure is shown.

[0026] Figure 6 A schematic diagram showing the configuration of first and second communication devices according to an embodiment of the present disclosure.

[0027] Figure 7 A schematic diagram of a communication method according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0028] In traditional communication systems, a single link between a transmitter and a receiver and its characteristics are the engineering targets. The typical metric that characterizes the upper limit of communication throughput for these systems is Shannon capacity, measured in bits per second per Hertz or bits per channel usage (bpcu). Shannon capacity (assuming an additive white Gaussian noise channel model (AWGN) below) can be determined based on the received signal-to-noise ratio (SNR) according to the following:

[0029]

[0030] The signal power is S and the noise power is N. The signal-to-noise ratio (S / N) is usually (in a linear system) related to the transmitted power P TX Typically, communication systems are designed in such a way that C is maximized, assuming that a single information source A and a single information receiver B are involved.

[0031] Assuming there is another information receiver E (also called "eavesdropper" or "Eve" for eavesdropping device) that can eavesdrop on the signal transmitted by A, this can be considered a confidential system. To quantify the confidentiality of a system, a common metric is the so-called confidentiality ratio (SR) C S, which is defined as the difference between the achievable rate for "A to B" and the achievable rate for "A to E":

[0032] C S = C(SNR A )-C(SNR E )

[0033] A simple visualization of this relationship is shown in Figure 1 Obviously, if the SNR A >>SNR E The best confidentiality rate can be achieved. Obviously, in SNR E >SNR A In the case of C S It may even become negative. Figure 1 This is also true for some areas.

[0034] In practical communication systems, the full Shannon capacity can never be achieved (limited A / D resolution, limited complexity, ...). Therefore, Figure 1 The secrecy rate shown can be viewed as an upper bound. A more realistic measure is the coded modulation (CM) capacity, which assumes an AWGN channel, discrete-valued input, continuous-valued output, and a modulation scheme for mapping binary information into symbols. For a uniform input distribution and a signal constellation letter χ with m bits per symbol (M-ary constellation, M = 2 m ), the CM capacity between the channel input X and output Y can be expressed as:

[0035]

[0036] Where E[.] is the expectation operator and P(.) is the conditional probability. Based on the CM capacity, a more realistic CM confidentiality rate can be defined and Figure 2 A more realistic measure of the data rate achievable over a single link is visualized in for a 4-QAM constellation. The difference between the two links gives a measure of confidentiality as shown below:

[0037] C S,cm =C cm (SNR A )-C cm (SNR E )

[0038] Another metric that can be used to define the confidentiality rate is the bit-interleaved coded modulation (BICM) capacity, which takes into account the additional practical constraints of the communication system. However, it is clear that when the SNR A High SNR E When the CM confidentiality rate is low, the highest CM confidentiality rate can be achieved. Figure 1The secrecy rates shown are opposite, and it can be seen that the secrecy rates of CM are asymptotic for both SNR parameters, thus limiting the curve to [-m, +m].

[0039] In a typical scenario, the SNRs of A and E are not independent but are proportional to the transmit power used by A. Therefore, the coupled CM confidentiality rate can be defined by introducing an attenuation factor α that defines the SNR offset between A and E:

[0040] SNR A | dB =P TX | dBm -P L | dB -P N,A | dBm

[0041] SNR E | dB =SNR A | dB +a| dB

[0042] Where P TX is the transmit power, A / EP N,A / E The path loss P under L Noise power, attenuation factor α. It should be noted that P RX | dBm =P TX | dBm -P L | dB Definition Considering path loss P L | dB The received signal power, path loss P L | dB can be considered as a constant offset and is therefore not considered further in the context of this disclosure. It is therefore defined as: P L | dB =0dB. Using this definition, we can prove that for every combination of α and χ there exists an optimal P TX , so that C S,cm Max. Figure 3 This relationship is visualized for the explanatory sets of χ and α in .

[0043] Therefore, for a secure communication system, an optimization goal can be defined to provide the highest possible CM confidentiality rate:

[0044] max{C S,cm (P TX ,χ,a)}

[0045] In addition, it can be considered that at a certain minimum communication rate / capacity Ctarget Maximizing the above metric under the additional constraint of yields the following constrained optimization problem:

[0046] max{C S,cm (P TX ,χ,a)}, where C cm (P TX ,χ,a)≥C target

[0047] Another formulation might aim to minimize the rate / capacity of the eavesdropping device:

[0048] min{C cm,E (P TX ,χ,a)}, where C cm,A (P TX ,χ,a)≥C target

[0049] In addition to the theoretical security issues mentioned above, in the implementation of communication systems, in order to make the transmission more robust and prevent the influence of noise or interference, forward error correction codes (FEC) are usually used to protect the data. These codes are usually designed to minimize the bit error probability (bit error rate (BER)) in the received message for a given SNR or SNR range (or general channel conditions). Designing these codes to maximize the above metrics is another way to enhance physical layer security.

[0050] To achieve this goal, this paper presents a method designed to influence P specifically for mmWave communication systems. TX , χ and α.

[0051] The metrics for confidentiality introduced above provide one possible view on the problem of providing confidentiality in a communication system. Other possible metrics include:

[0052] Bit Error Rate (BER): The bit error rate observed by a potential eavesdropping device should be maximized (i.e., should be close to 1 / 2, meaning that half of the received bits are erroneous)

[0053] Packet Error Rate (PER): The PER observed by a potential eavesdropping device should be as high as possible (ie, close to 1, meaning that no received packet can be successfully decoded).

[0054] Signal-to-Noise Ratio Difference (μ): The SNR of the signal sent by A, observed at the dedicated receiving device B, compared to the SNR observed at the potential eavesdropping device E, should be as high as possible, μ = SNR AB | dB -SNR AE | dB .

[0055] The amount of information sent from A to B should be maximized or at least reach a certain threshold, while the confusion of B should be maximized.

[0056] Based on the privacy metric used, there are generally a number of methods by which a station (STA) and an access point (AP) can exploit spatial diversity to prevent other stations (such as stations sharing the same encryption secret in the same network) from eavesdropping on the communication between the station and the access point. The same method can also be used for direct communication between two stations or in other communication systems besides WLAN.

[0057] High frequency wireless communications, such as 60 GHz WLAN, use directional wave radiation (beams) between a transmitter (TX) and a receiver (RX) to cover uniform medium distances, since omnidirectional radiation patterns, as used in lower frequencies, suffer from strong attenuation. Therefore, the two communication partners, such as a STA and an AP, use a beamforming antenna configuration that is initially learned and continuously updated to adapt to changing conditions such as displacement or obstruction. Intuitively, the best communication path between the two parties is one where the transmit and receive beams are perpendicular to each other in a straight line (line of sight, LoS). However, in a typical case, there are reflections that form an indirect path between the sender and the receiver, and the direct path may not be the best path due to obstacles / materials to be penetrated. But in any case, if communication is possible at all, there may be a set of beam configurations (or sub-streams) that, if some or all of them are used together, offer the potential for a spatial diversity communication approach. It can be shown that, if a sufficient number of reflected path components is used, the probability that the eavesdropping device is in a position where it can receive the same complete superposition of substreams as the legitimate receiver is almost zero, simply because it cannot be in the same position where all substreams can be decoded into a complete information set.

[0058] In order to enhance the confidentiality of the communication system, the following embodiments of the present disclosure can be applied individually or in combination. As an overall goal, it can be stated that the embodiments are directed to detecting the presence and location of potential eavesdropping devices. This information is then optionally used to reduce (or even minimize) the probability of eavesdropping, and preferably optimize (or even maximize) the confidentiality rate SR.

[0059] For example, the confidentiality rate may be considered as a metric, in which case the security criterion should be maximized (which may be expressed as the maximum of {confidentiality rate / CM SR / BICM SR} or the minimum of {bit error rate at the eavesdropping device}) to minimize the probability of eavesdropping by a third device. Other forms of security metrics / criteria may be used, such as minimizing the bit error rate (BER) at the eavesdropping device.

[0060] like Figure 3 As shown, basically three parameters PTX , χ and α affect the CMSR of the communication system. In millimeter wave communication systems that use phased array antennas (PAA) to focus the transmitted signal power and receive sensitivity in space (called beamforming), the beam to be used is selected during the beamforming process. Depending on the selected beam and the scenario (spatial and location of the device), the attenuation factor α can be considered as the result of the procedure.

[0061] In millimeter wave communications, usually both communication devices are equipped with PAAs, resonating in the corresponding frequency bands. Electromagnetic waves embedded in the antenna surface interact with the antenna structure based on two scattering phenomena: The first scattering is the so-called structural mode scattering caused by the metal conductor of the antenna. The rest of the power is actually fed into the antenna connector, where the impedance mismatch reflects part of the energy back to the radiating part of the antenna, where the signal is then radiated again. This phenomenon is called antenna mode scattering.

[0062] In radio detection and ranging (RADAR) applications, a radar antenna transmits a signal in different directions and receives echoes of this signal reflected by a "target". The reflected signal power P is usually modeled by the so-called radar cross section (RCS) σ RX Therefore, the amount of received signal power can be modeled as follows:

[0063]

[0064] ,in

[0065] —The power of the transmitted signal P TX ,

[0066] —The gain of the transmitting antenna in the direction of the target, G TX (In the case of a steerable antenna, this may depend on the direction in which the antenna is steered (or the selected antenna beam)

[0067] — distance to the target, r,

[0068] —Receiving antenna to echo direction Gain G RX ,

[0069] —Received noise power Pn.

[0070] The higher σ is, the lower the distance to the reflector is and the higher the echo signal power that can be detected at the receiving antenna.

[0071] In antenna terms, the amount of electric field reflected (scattered or reradiated) from the receiving antenna structure can be divided into two different components:

[0072] i) Antenna pattern scattering, which depends on the antenna gain G, the matched or unmatched load Z attached to the antenna network L , and other antenna parameters such as polarization or angle of arrival.

[0073] ii) Residual mode scattering (or structural component of RCS), which describes any other contribution that cannot be classified into the first category in order to fully describe the total radar cross section of the antenna structure. These components generally depend on all parameters such as the structure of the antenna, the materials used, etc., but by definition do not depend on the load impedance Z attached to the antenna output port. L .

[0074] Antenna mode scattering and residual mode scattering can lead to an increase in the radar cross section of a 60 GHz capable WLAN device that is able to dynamically "listen" to the direction of a transmitting device. These effects can be combined with the radio cross section of the antenna and modeled.

[0075] Furthermore, the RCS of any "target" depends on the signal frequency used by the sender to generate the echo. The actual frequency dependence, as well as the estimate of the RCS, can be used to classify the target as an antenna device / potential eavesdropping device or a passive scatterer / obstacle. This can be achieved by matching the frequency-dependent echo signal (spectrum) of the detected target with a set of known spectra (e.g., by correlation or other distance or similarity measures).

[0076] Furthermore, the first communication device may use one or more of these properties to differentiate between different devices. Specifically, the communication device may use the estimated RCS and its frequency-dependent characteristics as a signal that may detect whether a potential eavesdropping device is pretending to be a legitimate receiver.

[0077] In a preferred embodiment of WLAN in the 60 GHz band, the simulated beam tested during the simulated beam training can be used as a probe signal. This is part of the sector level scanning (SLS) phase, or subsequent beam refinement. Such a directional beam can then be used as a probe signal to detect the presence of a potential eavesdropping device E. In order to detect a potential eavesdropping device, it is not necessary to cover 360 degrees around the transmitting device, because subsequent communications between the transmitting device and the intended receiving devices (A and B) will only occur on one of the previously tested beams (i.e., the eavesdropping device may be located on a blind spot and not detected, but no signal is sent to that point / area).

[0078] It can be assumed that the transmitting device A knows the location of the intended receiving device B. This can be achieved, for example, as a byproduct of the SLS and beam refinement phases, in which both A and B participate. For each tested beam direction (probing signal), the angle of departure (AoA) from A to B is known at A (either hardwired or estimated from the phase settings at the phased antenna array (PAA)). Other known positioning techniques, such as precise time measurement (estimate and send the time of flight information of the signal from A to B and the angle of arrival (AoA) at the receiving device B), can further improve the positioning of B. At least after the potential eavesdropping device is detected, the direction (without knowing the distance) of B is sufficient for most countermeasures.

[0079] After establishing a communication link between A and B, where B's location (or at least B's direction) is known, a probe signal from A will scan for the location of potential eavesdropping devices. Once the reflection of the probe signal comes back to A, A can mark that direction as the direction of a potential eavesdropping device. It could also be a reflection from an object or a non-malicious device (without intention to eavesdrop), but for security reasons, the origin of that reflection may be marked as the direction of a potential eavesdropping device. As a next step, A may not transmit in this direction, but instead initiate countermeasures to interfere with potential eavesdropping (even if E is not in the area where A is transmitting, it can still capture some energy from the electromagnetic waves; PAA can focus the transmitted energy in one direction, but leakage is always possible, for example through the side lobes of the beam).

[0080] One countermeasure for A is to send a jamming signal or artificial noise in the direction of the potential eavesdropping device. This can be pseudo-noise (e.g., following a Gaussian distribution to obtain maximum entropy, i.e., maximum uncertainty) or another jamming signal. This can be done simultaneously, when multiple PAAs are deployed at the transmitting device A (hybrid MIMO architecture), while the desired signal is sent to B. If B and E are on the same line originating from A (i.e., B and E are in the same direction), secure communication may not be guaranteed. However, if the distance is also known (e.g., observing the flight time from reflections (from B and E) to A), then a parabolic phase shifter setting can be used at A's PAA to focus the transmit power of the desired signal at B's location and send an interfering signal focused at E's location. Another countermeasure would be to initiate spatial hopping, i.e., to cut the desired signal into small blocks, each block using a different beam to transmit in a different direction (ideally excluding the direction towards E). Only those beams that end at B's location will be used, possibly through reflection (non-line of sight (NLOS) link). These beams are not necessarily the best beams for data transmission from A to B, but may be good enough to allow secure communication. It is highly unlikely that an eavesdropping device E would intercept a small fraction of the energy from all of these beams, since E is located at a different location than B (even though E may be located in the same direction).

[0081] This allows the first communication device ( Figure 4A and 4B A in FIG. 1 illustrates an embodiment of improving the security of information transmission according to the present disclosure) by systematically transmitting detection signals 1 to 5 (see Figure 4A ) is sent in different directions and potential echoes 6 (from the second communication device) and 7 (from the potential eavesdropping device) are detected to detect the direction of the potential eavesdropping device E. Subsequently, now that A knows the position of E relative to A (at least the direction of the position), A can, for example, systematically interfere with E by sending a noise signal 8 in its direction, preferably in parallel sending a message 9 in the direction of B. Thus, the noise signal 8 is sent so that it does not interfere with B, and the message 9 is sent so that it is not received by E. However, in this context, it should be noted that B is still able to decode the message (but E is not). Typically, separate antenna circuits (e.g., antenna arrays) are used to send the detection signal and receive the echo signal, which enables the detection signal to be sent and the echo signal to be received simultaneously (e.g., using multiple antenna beams of the antenna circuit used to receive the echo signal). In other embodiments, the same antenna circuit is used to transmit the detection signal and receive the echo signal.

[0082] In one embodiment, A is equipped with two different phased array antennas A1 and A2, such as Figure 4A and 4B In this embodiment, the first PAA A1 transmits a detection signal using different beams 1 to 5 in the angular domain, taking advantage of the inevitable radar cross section of the antenna array of the eavesdropping device to detect the eavesdropping device. Therefore, part of the energy is directly transmitted back from E to A to enable detection of E. A can also use a different beam of the second PAA A2 in the angular domain and receive the echo of its transmitted signal, which (according to equation (1)) is increased by G RX To increase the received signal power. In addition, through the angular resolution, the second PAA A2 can directly interfere with E, thereby enhancing the security of message exchange and communication between A and B. Generally, B and E can be detected from the received echo signal by evaluating one or more properties of the received echo signal (such as power and / or delay and / or direction and / or estimated effective cross section).

[0083] Preferably, if Figure 4A As shown, A transmits probing signals 1 to 5 into multiple spatial directions using one RF chain in an H-MIMO (H-MIMO) configuration, and receives potential echoes 6 and 7 reflected by B and E. After locating B and E, in one embodiment, A can transmit a secret message 9 to B using different beam directions (and optionally different beam widths) while specifically interfering with E using a noise signal 8.

[0084] Figure 5A schematic diagram of a communication system in which the present disclosure can be applied is shown. The communication system is configured with a first communication device 10 (e.g., representing device A) and one or more second communication devices 20 (e.g., representing one or more devices B). Each of the first communication device 10 and the second communication device 20 has a wireless communication function. Specifically, the first communication device 10 has a communication function of sending a frame to one or more second communication devices 20. In addition, in an embodiment, the first communication device 10 operates as an access point (AP) and the second communication device 20 operates as a station (STA); in other embodiments, both devices 10 and 20 can operate as stations. Communication from AP 10 to STA 20 is called a downlink (DL), and communication from STA 20 to AP 10 is called an uplink (UL).

[0085] For example, Figure 5 As shown, the communication system may be configured with an AP 10 and one or more STAs 20a to 20d. In addition, there may be a potential eavesdropping device E, for example, seeking to eavesdrop on the communication between the AP 10 and one or more of the STAs. The AP 10 and the STAs 20a to 20d are connected to each other through wireless communication, and directly perform transmission and reception of frames with each other. For example, the AP 10 is a communication device compliant with the IEEE 802.11 standard, and transmits a MUDL PPDU (Multi-User Downlink PHY Protocol Data Unit) having each of the STAs 20a to 20d as a destination.

[0086] Figure 6 FIG. 1 is a schematic diagram showing a configuration of a communication device 30 according to an embodiment of the present disclosure. In general, each of the AP 10 and the STAs 20a to 20d may be configured as follows: Figure 6 As shown, the system may include a data processing unit 31 , a wireless communication unit 32 , a control unit 33 and a storage unit 34 .

[0087] As a part of the communication device 30, the data processing unit 31 performs processing on data for transmission and reception. Specifically, the data processing unit 31 generates a frame based on data from a higher layer of the communication device 30, and transmits the generated frame to the wireless communication unit 32. For example, the data processing unit 31 generates a frame (specifically, a MAC frame) from the data by performing processes such as fragmentation, segmentation, aggregation, adding a MAC header for media access control (MAC), adding an error detection code, and the like. In addition, the data processing unit 31 extracts data from the received frame and provides the extracted data to a higher layer of the communication device 30. For example, the data processing unit 31 obtains data by analyzing the MAC header, detecting and correcting code errors, and performing reordering processing on the received frame.

[0088] The wireless communication unit 32 has signal processing functions, wireless interface functions, etc. as part of the communication unit. In addition, beamforming functions are provided. The unit generates and sends PHY layer data packets (or, in particular for WLAN standards, PHY layer protocol data units (PPDUs)).

[0089] The signal processing function is a function of performing signal processing such as modulation on a frame. Specifically, the wireless communication unit 32 performs encoding, interleaving, and modulation on the frame provided from the data processing unit 31 according to the encoding and modulation scheme set by the control unit 33, adds a preamble and a PHY header, and generates a PHY layer data packet. In addition, the wireless communication unit 32 restores the frame by performing demodulation, decoding, etc. on the PHY layer data packet obtained by the processing of the wireless interface function, and provides the obtained frame to the data processing unit 31 or the control unit 33.

[0090] The wireless interface function is a function of sending / receiving signals via one or more antennas. Specifically, the wireless communication unit 32 converts the signal related to the symbol stream obtained by the processing performed by the signal processing function into an analog signal, amplifies the signal, filters the signal, and converts the frequency up. Next, the wireless communication unit 32 transmits the processed signal via the antenna. In addition, for the signal obtained via the antenna, the wireless communication unit 32 performs processing opposite to the processing when the signal is transmitted, such as frequency down conversion or digital signal conversion.

[0091] The beamforming function performs analog beamforming and / or digital beamforming, including beamforming training, as is generally known in the art.

[0092] As a part of the communication unit, the control unit 33 (e.g., a station management entity (SME)) controls the overall operation of the communication device 30. Specifically, the control unit 33 performs processing such as information exchange between functions, setting of communication parameters, or scheduling of frames (or data packets) in the data processing unit 31.

[0093] The storage unit 34 stores information for processing by the data processing unit 31 or the control unit 33. Specifically, the storage unit 34 stores information stored in a transmission frame, information acquired from a reception frame, information on communication parameters, and the like.

[0094] In an alternative embodiment, each of the first and second communication devices, specifically the AP 10 and the STA 20, can be implemented by using Figure 6 The units shown and the circuits to be performed are configured. The circuits may be implemented, for example, by a programmed processor. Typically, the functions of the first and second communication devices and Figure 6 The units of the communication device 30 shown in FIG. 3 may be implemented in software, hardware, or a mixture of software and hardware.

[0095] Figure 7 An embodiment of a communication method of a first communication device for communicating with a second communication device in a wireless communication system according to the present disclosure is shown. In a first step S10, the first communication device sends a detection signal to multiple directions. The first communication device immediately or thereafter receives an echo signal in response to the sent detection signal (step S12). Based on the received echo signal, the first communication device determines at least the location of the potential eavesdropping communication device in step S14. Optionally, in an embodiment, the location of the second communication device is also determined (step S16).

[0096] In one embodiment, the knowledge of the position of the second communication device is used by the first communication device in step S18 to send a message in a first direction suitable for exchanging information with the second communication device. The first direction can thus be determined based on the position of the second communication device and / or the received echo signal. In one embodiment, step S18 and step S20 can be performed simultaneously.

[0097] In another embodiment, the first communication device sends noise to a second direction suitable for reaching the potential eavesdropping communication device (step S20). Thus, the second direction can be determined according to the position of the potential eavesdropping communication device and / or the received echo signal.

[0098] The transmission of noise can be performed simultaneously with the transmission of the message.

[0099] Another embodiment may be configured to differentiate between potential eavesdropping communication devices and non-critical communication devices (including the second communication device, but also other communication devices that are not potential eavesdropping devices) based on the metric.

[0100] Another embodiment may be configured to distinguish between potential eavesdropping communication devices and non-critical communication devices based on a metric using one or more properties of the reflected signal, including the amount of reflected signal energy, frequency selectivity, signal amplitude, and signal phase.

[0101] The disclosed solution is well suited for future product adoption according to the IEEE 802.11ay standard or its amendments, since i) it exploits millimeter waves, in particular the hybrid MIMO concept required for those products, and ii) may find application in Internet of Things (IoT) use cases where physical layer security is required because constraints such as computational complexity or power consumption indicate the application of traditional cryptographic methods. Furthermore, the disclosed technique is advantageous when pre-processing of the signal rather than the payload information is required, which is the case with traditional encryption.

[0102] An example is the transmission of the location of a tracking device. When device A sends its location information to base station B, it can encrypt the location information, but when sending the encrypted message, A discloses its location (from the transmitted waveform itself). Therefore, a potential eavesdropping device that receives the encrypted signal in multiple locations can triangulate A's location.

[0103] Therefore, the foregoing discussion discloses and describes only exemplary embodiments of the present disclosure. As will be appreciated by those skilled in the art, the present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. Therefore, the disclosure of the present disclosure is intended to illustrate rather than limit the scope of the present disclosure and other claims. The present disclosure, including any readily recognizable variants taught herein, partially defines the scope of the preceding claim terms, thereby not dedicating the subject matter of the present invention to the public.

[0104] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0105] Whenever the embodiments of the present disclosure are described as being implemented at least in part by a data processing device controlled by software, it will be understood that non-transitory machine-readable media carrying such software, such as optical disks, magnetic disks, semiconductor memories, etc., are also considered to represent embodiments of the present disclosure. In addition, such software may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.

[0106] The components of the disclosed devices, apparatuses and systems may be implemented by corresponding hardware and / or software components, such as application specific circuits or circuits. A circuit is a structural combination of electronic components including common circuit elements, integrated circuits including application specific integrated circuits, standard integrated circuits, application specific standard products and field programmable gate arrays. In addition, the circuit includes a central processing unit, a graphics processing unit and a microprocessor programmed or configured according to software code. The circuit does not include pure software, although the circuit includes the above-mentioned hardware executing software. One or more circuits may be implemented by a single device or unit or multiple devices or units, chipsets or processors.

[0107] It follows a list of further embodiments of the disclosed subject matter:

[0108] 1. A first communication device, used for communicating with a second communication device in a wireless communication system, wherein the first communication device comprises a circuit, wherein the circuit is configured to

[0109] Send out detection signals in multiple directions.

[0110] receiving an echo signal in response to the transmitted detection signal, and

[0111] The location of a potential eavesdropping communication device is determined based on the received echo signal.

[0112] 2. The first communication device according to embodiment 1,

[0113] The circuit is configured to send a message in a first direction suitable for exchanging information with the second communication device.

[0114] 3. The first communication device according to embodiment 2,

[0115] The circuit is configured to determine the location of the second communication device based on the received echo signal and determine the first direction to which the message is subsequently sent.

[0116] 4. The first communication device of any preceding embodiment, wherein the circuit is configured to emit noise into a second direction suitable for reaching a potential eavesdropping communication device.

[0117] 5. The first communication device according to embodiments 2 and 4,

[0118] Wherein, the circuit is configured to send the message and the noise simultaneously or at least partially simultaneously.

[0119] 6. The first communication device according to embodiments 2 and 4,

[0120] The circuit includes a first antenna circuit configured to send the message and a second antenna circuit configured to send the noise.

[0121] 7. The first communication device according to embodiment 6,

[0122] Wherein, the first antenna circuit and the second antenna circuit each include a phased antenna array.

[0123] 8. The first communication device according to any one of embodiments 3 to 7,

[0124] Wherein the circuit is configured to send the message using a message antenna beam covering the location of the second communication device.

[0125] 9. The first communication device according to any one of embodiments 2 to 8,

[0126] Wherein the circuit is configured to send the message using the message antenna beam that does not cover the location of a potential eavesdropping communication device.

[0127] 10. The first communication device according to any one of the preceding embodiments,

[0128] The circuit is configured to transmit noise using a noise antenna beam, wherein the noise antenna

[0129] The beam does not cover the location of the second communication device and covers the location of the potential eavesdropping communication device.

[0130] 11. The first communication device according to any one of the preceding embodiments,

[0131] Wherein, the circuit is configured to send a probing signal using multiple probing antenna beams.

[0132] 12. The first communication device according to any one of the preceding embodiments,

[0133] The circuit is configured to identify the second communication device and the potential eavesdropping communication device from the received echo signal by evaluating one or more properties of the received echo signal, wherein the properties include power, delay, direction and estimated effective cross section.

[0134] 13. The first communication device according to any one of the preceding embodiments,

[0135] The circuit includes a first antenna circuit configured to send the detection signal and a second antenna circuit configured to receive the echo signal.

[0136] 14. The first communication device according to any one of the preceding embodiments,

[0137] Wherein the circuit is configured to distinguish between potential eavesdropping communication devices and non-critical communication devices based on the metric.

[0138] 15. The first communication device according to embodiment 14,

[0139] The circuit is configured to distinguish between potential eavesdropping communication devices and non-critical communication devices based on a metric using one or more characteristics of the echo signal, including the amount of echo signal energy, frequency selectivity, signal amplitude, and signal phase.

[0140] 16. The first communication device according to any one of the preceding embodiments,

[0141] The circuit is configured to distinguish between a potential eavesdropping communication device and a non-critical communication device based on whether the communication device participates in a beamforming process with the first communication device.

[0142] 17. The first communication device according to any one of the preceding embodiments,

[0143] The circuit is configured to use a simulated beam tested during simulated beamforming training as a sounding signal.

[0144] 18. The first communication device according to any one of the preceding embodiments,

[0145] The circuit is configured to obtain the location of the second communication device and / or the potential eavesdropping device through one or more of beamforming training, beam refinement, or fine time measurement between the first communication device and the second communication device.

[0146] 19. The first communication device according to any one of the preceding embodiments,

[0147] The circuit is configured to focus the transmission power of the message at the location of the second communication device and to focus the noise at the location of the potential eavesdropping communication device.

[0148] 20. The first communication device according to any one of the preceding embodiments,

[0149] The circuit is configured to initiate space hopping by splitting a message into message parts and sending them in different directions.

[0150] 21. A first communication method of a first communication device, used for communicating with a second communication device in a wireless communication system, the first communication method comprising:

[0151] Send out detection signals in multiple directions.

[0152] receiving an echo signal in response to the transmitted detection signal, and

[0153] The location of a potential eavesdropping communication device is determined based on the received echo signal.

[0154] 22. A non-transitory computer-readable recording medium storing a computer program product, which, when executed by a processor, causes the method according to embodiment 21 to be performed.

[0155] 23. A computer program comprising program code means for causing a computer to perform the steps of the method according to embodiment 21 when the computer program is executed on the computer.

Claims

1. A first communication device for communicating with a second communication device in a wireless communication system, the first communication device comprising a circuit, wherein the circuit is configured to: Send out detection signals in multiple directions. receiving an echo signal in response to the transmitted detection signal, and determining the location of a potential eavesdropping communication device based on the received echo signal, in, The circuit is configured to identify the second communication device and the potential eavesdropping communication device based on the received echo signal by evaluating one or more properties of the received echo signal, the properties including power, delay, direction, and estimated effective cross section, The circuit is configured to distinguish the second communication device from the potential eavesdropping communication device based on whether the communication device participates in a beamforming process with the first communication device.

2. The first communication device according to claim 1, in, The circuit is configured to transmit a message to a first direction suitable for exchanging information with the second communication device.

3. The first communication device according to claim 2, in, The circuit is configured to determine a location of the second communication device based on the received echo signal and determine the first direction to which the message is subsequently transmitted.

4. The first communication device according to claim 2, in, The circuit is configured to emit noise in a second direction suitable for reaching the potential eavesdropping communication device.

5. The first communication device according to claim 4, in, The circuit is configured to transmit the message and the noise simultaneously or at least partially simultaneously.

6. The first communication device according to claim 4, in, The circuit includes a first antenna circuit configured to transmit the message and a second antenna circuit configured to transmit the noise.

7. The first communication device according to claim 6, in, The first antenna circuit and the second antenna circuit each include a phased antenna array.

8. The first communication device according to claim 3, in, The circuit is configured to transmit the message using a message antenna beam, the message antenna beam covering the location of the second communication device.

9. The first communication device according to claim 2, in, The circuitry is configured to transmit the message using a message antenna beam that does not cover a location of the potential eavesdropping communication device.

10. The first communication device according to claim 1, in, The circuit is configured to transmit the noise using a noise antenna beam, the noise antenna beam not covering a location of the second communication device and the noise antenna beam covering a location of the potential eavesdropping communication device.

11. The first communication device according to claim 1, in, The circuit is configured to transmit the probing signal using a plurality of probing antenna beams.

12. The first communication device according to claim 1, in, The circuit includes a first antenna circuit configured to transmit the detection signal and a second antenna circuit configured to receive the return signal.

13. The first communication device according to claim 1, in, The circuit is configured to distinguish between the potential eavesdropping communication devices and non-critical communication devices based on a metric.

14. The first communication device according to claim 13, in, The circuit is configured to distinguish between the potential eavesdropping communication device and the non-critical communication device based on a metric using one or more properties of the reflected signal, including an amount of reflected signal energy, frequency selectivity, signal amplitude, and signal phase.

15. The first communication device according to claim 1, in, The circuit is configured to use a simulated beam tested during the simulated beamforming training as a sounding signal.

16. The first communication device according to claim 1, in, The circuit is configured to obtain the location of the second communication device and / or the potential eavesdropping communication device through one or more of beamforming training, beam refinement, or fine time measurement between the first communication device and the second communication device.

17. A first communication method for the first communication device according to claim 1, the first communication method comprising: Send out detection signals in multiple directions. receiving an echo signal in response to the transmitted detection signal, and The location of the potential eavesdropping communication device is determined based on the received echo signal.

18. A non-transitory computer-readable recording medium storing a computer program product, which, when executed by a processor, causes the method according to claim 17 to be performed.

Images