Obfuscation of hardware-specific identification information

Abstract

A method for obfuscating hardware-specific identification information of a user equipment, UE, (2) in a communications network (9) to hinder radio frequency fingerprinting, RFF, of the UE is provided, the method being performed by the UE (2) configured to hinder the RFF. The method comprises, upon receiving (40) a request (20) for transmitting specific uplink data; transmitting (46) obfuscated uplink data (22) to a radio network node (1), the obfuscated uplink data (22) having been constructed by applying at least one parameter for obfuscating hardware-specific identification information to the specific uplink data, which hardware-specific identification information can otherwise be used for RFF of the UE (2) based on uplink transmissions of the UE (2). A UE (2), a computer program (67, 91) and a computer program product (64, 90) are also disclosed.

Description

Technical Field

[0001] This invention generally relates to the field of communication networks, and more specifically to a method, user equipment, computer program, and computer program product for obfuscating hardware-specific identification information to impede the radio frequency fingerprinting (RFF) of a user equipment for such communication networks. Background Technology

[0002] In modern communication systems, the physical layer of the network has become an increasingly important aspect of security. Radio frequency fingerprinting (RFF) has emerged as a novel method for physical layer security, leveraging inherent and unique hardware flaws in radio transmitters to authenticate devices, thereby enhancing the trustworthiness of telecommunications infrastructure. Therefore, RFF can be used to authenticate user equipment (UE) or any other wireless device in a communication network.

[0003] The article entitled “Radio Frequency Fingerprinting via Deep Learning: Challenges and Opportunities” (arXiv:2310.16406v1), published by Al-Hazbi et al. and available at https: / / arxiv.org / abs / 2310.16406v1 at the time of filing this patent application, provides an overview of the currently unresolved issues preventing the practical deployment of deep learning-based RFF systems, while also discussing promising research opportunities for enhancing the overall accuracy, robustness, and privacy of these systems.

[0004] While RFF is innovative, it raises considerable privacy concerns, especially given the differing international regulations designed to protect user privacy. Traditional RFF techniques, while useful for security, inadvertently create the risk that device-specific signatures could be used for malicious activities such as unauthorized tracking, profiling, and spoofing attacks.

[0005] There are no adequate solutions in the existing technology to address the important aspects of defending against potential abuse by unauthorized or rogue networks. Summary of the Invention

[0006] One objective is to protect user privacy and prevent unintended exploitation of RFF.

[0007] According to a first aspect, a method is provided for obfuscating hardware-specific identification information of a user equipment (UE) in a communication network to prevent the UE from using a radio frequency fingerprinting (RFF). The method is performed by the UE configured to prevent the RFF, and the method includes: upon receiving a request to transmit specific uplink data; transmitting obfuscated uplink data to a radio network node, the obfuscated uplink data having been constructed by applying at least one parameter to the specific uplink data for obfuscating hardware-specific identification information, which may otherwise be used in the UE's RFF based on uplink transmissions.

[0008] The method may further include: determining that the UE is configured to block RFF.

[0009] The method may further include: determining at least one parameter used to obfuscate hardware-specific identification information.

[0010] The request may be an RFF-based authentication request issued by the radio network node.

[0011] The at least one parameter may include an offset for the at least one QAM symbol in one or both of the in-phase I component and the quadrature Q component.

[0012] The at least one parameter may include an offset for the bias used in the power amplifier or an offset for the power level.

[0013] The at least one parameter may include digital predistortion (DPD) parameters, which are determined to be mismatched with the power amplifiers used for uplink transmission of the UE.

[0014] The at least one parameter can be determined based on a random number source or a pseudo-random number source.

[0015] The method may further include: sending an uplink transmission including user data when applying the at least one parameter.

[0016] The method may further include: sending a privacy request to the network node to remove all RFF data used by the UE.

[0017] The communication network may be a cellular network.

[0018] According to a second aspect, a user equipment (UE) is provided for obfuscating hardware-specific identification information of the UE to prevent the UE from using radio frequency fingerprinting (RFF). The UE is configured to form part of a communication network. The UE includes: processing circuitry; and memory circuitry storing instructions that, when executed by the processing circuitry, cause the UE to: upon receiving a request to transmit specific uplink data; transmit obfuscated uplink data to a radio network node, the obfuscated uplink data having been constructed by applying at least one parameter to the specific uplink data for obfuscating hardware-specific identification information, which may otherwise be used in the UE's RFF based on uplink transmissions.

[0019] The UE may also include instructions that, when executed by the processing circuitry, cause the UE to: determine that the UE is configured to block RFF.

[0020] The UE may also include instructions that, when executed by the processing circuitry, cause the UE to: determine the at least one parameter for obfuscating hardware-specific identification information.

[0021] The request may be an RFF-based authentication request issued by the radio network node.

[0022] The at least one parameter may include an offset for the at least one QAM symbol in one or both of the in-phase I component and the quadrature Q component.

[0023] The at least one parameter may include an offset to the bias used for the power amplifier or an offset to the power back-off level.

[0024] The at least one parameter may include digital predistortion (DPD) parameters, which are determined to be mismatched with the power amplifiers used for uplink transmission of the UE.

[0025] The at least one parameter can be determined based on a random number source or a pseudo-random number source.

[0026] The UE may also include instructions that, when executed by the processing circuit, cause the UE to: send an uplink transmission including user data when applying the at least one parameter.

[0027] The UE may also include instructions that, when executed by the processing circuitry, cause the UE to: send a privacy request to the network node to remove all RFF data used by the UE.

[0028] The communication network may be a cellular network.

[0029] According to a third aspect, a computer program is provided for obfuscating hardware-specific identification information of a user equipment (UE) in a communication network to prevent the UE from using radio frequency fingerprinting (RFF). The computer program includes computer program code that, when executed on the UE, causes the UE to: upon receiving a request to transmit specific uplink data; transmit obfuscated uplink data to a radio network node, the obfuscated uplink data having been constructed by applying at least one parameter to the specific uplink data for obfuscating hardware-specific identification information, which may otherwise be used in the UE's RFF based on uplink transmissions.

[0030] According to a fourth aspect, a computer program product is provided, comprising a computer program according to a third aspect and a computer-readable device, the computer-readable device including a non-transitory memory in which the computer program is stored.

[0031] Generally, all terms used in the claims should be interpreted according to their ordinary meaning in the technical field, unless otherwise expressly defined herein. All references to “a / the element, device, component, apparatus, step, etc.” should be openly interpreted as referring to at least one instance of an element, device, component, apparatus, step, etc., unless otherwise expressly stated. The steps of any method disclosed herein need not be performed in the exact order disclosed, unless expressly stated. Attached Figure Description

[0032] Aspects and embodiments will now be described by way of example with reference to the accompanying drawings, in which:

[0033] Figure 1 This is a schematic diagram illustrating an environment in which the embodiments presented herein can be applied;

[0034] Figure 2 The illustration is based on one embodiment. Figure 1 A schematic diagram of the UE's transmission chain;

[0035] Figures 3A-3C This is a swimlane diagram illustrating an embodiment of a method for obfuscating hardware-specific identification information of the UE to prevent RFF;

[0036] Figure 4 The illustration is based on one embodiment. Figure 1 A schematic diagram of some components of the UE;

[0037] Figure 5 This illustrates an embodiment. Figure 1 A schematic diagram of the functional modules of the UE; and

[0038] Figure 6 An example of a computer program product that includes a computer-readable device is shown. Detailed Implementation

[0039] Aspects of this disclosure will now be described more fully below with reference to the accompanying drawings, in which certain embodiments of the invention are illustrated. However, these aspects may be embodied in many different forms and should not be construed as limiting; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of all aspects of the invention to those skilled in the art. Throughout the description, the same numerals refer to the same elements.

[0040] According to the embodiments presented herein, the UE's RFF is blocked by obfuscating hardware-specific identification information in the UE's transport chain. This prevents the receiver from inferring the hardware-specific characteristics used to identify the UE.

[0041] Figure 1 This is a schematic diagram illustrating an environment in which the embodiments presented herein can be applied. The communication network 9 includes a core network 3 and one or more radio network nodes 1, here in the form of gNode B (also known as gNB). The radio network node 1 can also be in the form of an eNode B, node B, etc., or any other suitable base station or access point. The radio network node 1 forms part of a radio access network (RAN) and provides radio connectivity to one or more UEs 2 via a radio interface 4. Although applicable to multiple UEs, for ease of understanding and clarity, the relationship with one radio network node 1 and one UE 2 is described below. The term UE 2 is also referred to as a mobile communication terminal, wireless device, mobile terminal, user terminal, user agent, wireless terminal, machine-to-machine device, etc., and can be implemented, for example, in what is commonly referred to today as a mobile phone, smartphone, IoT device, or tablet / laptop with wireless connectivity. The communication network 9 can be a cellular communication network or a non-cellular network (e.g., a Wi-Fi network).

[0042] Cellular Network 9 may, for example, comply with any or a combination of 5G (fifth generation), 6G (sixth generation), LTE (Long Term Evolution), LTE Advanced, W-CDMA (Wideband Code Division Multiple Access), IEEE 802.11 (Wi-Fi), or any other current or future wireless network, provided that the principles described below apply.

[0043] Downlink (DL) communication occurs from radio network node 1 to UE 2 via radio interface 4, and uplink (UL) communication occurs from UE 2 to radio network node 1. Due to factors such as fading, multipath propagation, and interference, the quality of the radio interface to each UE 2 varies over time and depends on the location of UE 2.

[0044] Depending on the RAN, radio network node 1 may optionally connect to core network 3 to connect to central functions and wide area network 7 (such as the Internet).

[0045] Figure 2 The illustration is based on one embodiment. Figure 1 A schematic diagram of transmission chain 7 of UE 2. Transmission chain 7 includes a baseband module 10, which performs digital domain transmission processing of the data to be transmitted. The next module is a digital-to-analog converter (DAC) 11, which converts the digital domain signal into an analog signal. Once converted, the analog signal is at the baseband frequency. A mixer 12 upconverts the baseband analog signal into an analog signal at the radio frequency (RF) frequency. The RF signal is fed to a power amplifier 13 for appropriate amplification before being transmitted over the air using antenna 14.

[0046] Figures 3A-3C This is a swimlane diagram illustrating an embodiment of a method for obfuscating the hardware-specific identification information of UE 2 to prevent the UE from performing an RFF when radio network node 1 attempts to perform an RFF. The swimlane diagram can be considered as including flowcharts of the method performed by UE 2 on the left and flowcharts of the method performed by radio network node 1 on the right. Communication between the entities is also shown.

[0047] First look Figure 3A In step 140 of sending a UL tx (transmission) request, radio network node 1 sends a UL transmission request 20 to UE 2.

[0048] In step 40 of receiving a UL tx (transmission) request, UE 2 receives a request to transmit specific uplink data, namely UL transmission request 20, which includes a specific configuration of the UL data to be transmitted. UL transmission request 20 may be, for example, a request for RFF-based authentication, and UL transmission request 20 may be issued by the radio network node in step 140 of sending a UL tx request as described above. The specific uplink data includes data known to radio network node 1 to allow radio network node 1 to evaluate how the specific uplink data is transformed by transmission chain 7, thereby revealing, for example, hardware-specific identification information related to nonlinearities in transmission chain 7. For example, the specific uplink data may include a reference signal or nonlinear profile / signature to be transmitted by the UE. However, according to the embodiments presented herein, as explained in more detail below, the specific uplink data is obfuscated prior to transmission.

[0049] Upon receiving UL transmission request 20, in step 46 of sending specific UL data, UE 2 sends obfuscated uplink data 22 to radio network node 1. The obfuscated uplink data is constructed by applying at least one parameter (generated according to UL transmission request 20) to the specific uplink data for obfuscating hardware-specific identification information, which may otherwise be used in the UE's RFF based on the UE's uplink transmission.

[0050] In one embodiment, the at least one parameter includes an offset of at least one modulation symbol (e.g., a quadrature amplitude modulation (QAM) symbol) in one or both of its in-phase (I) and quadrature (Q) components. This offset can be applied in the digital domain (e.g., in baseband module 10) or in the analog domain (e.g., after DAC 11).

[0051] In one embodiment, the at least one parameter includes an offset to the bias used for power amplifier 13, or an offset to the power level. The bias affects the linearity of power amplifier 13, and any change in the bias will also affect the RFF based on the nonlinearity of the UE transmission chain. Adjusting the power back-off level also affects linearity, and therefore also affects the ability to use the RFF based on the nonlinearity of the UE transmission chain 7.

[0052] In one embodiment, the at least one parameter includes a digital predistortion (DPD) parameter, which is determined to cause them to mismatch with the power amplifier used for uplink transmission of the UE. Since the DPD parameter is customized for each UE to compensate for nonlinearities in the power amplifier, any change to the DPD parameter will result in different nonlinear outcomes.

[0053] In one embodiment, the at least one parameter is determined based on a random number source or a pseudo-random number source. Randomizing at least one parameter increases the difficulty for any radio network node 1 to compensate for scrambling based on at least one parameter.

[0054] For each RFF-related request, at least one parameter can be unique. This prevents radio network node 1 from finding at least one parameter by tracking transmissions over time. Alternatively, the same at least one parameter can be applied to multiple RFF-related requests, for example, during a specific time period, to avoid having to generate at least one parameter for each RFF-related request.

[0055] In step 146 of receiving specific UL data, radio network node 1 receives garbled uplink data 22.

[0056] In the RFF attempt step 150, radio network node 1 attempts to perform an RFF based on the received obfuscated UL data 22 and using knowledge of specific UL data or CCDF (Complementary Cumulative Distribution Function) that radio network node 1 expects UE 2 to send. However, due to obfuscation, the RFF will be hindered, making it very difficult or even impossible, because it will be impossible to derive the true hardware-specific changes from the obfuscated uplink data 22.

[0057] Regarding the CCDF, a Fourier transform is performed from the UE perspective to minimize the PAPR (Peak-to-Average Power Ratio) and the corresponding linearity. In this way, the CCDF for a given uplink signal is relatively uniform. If an RFF model is available for a given UE output power (and corresponding CCDF), then any signal at that output power will have a similar CCDF and therefore similar nonlinearity, thus allowing for UE identification.

[0058] Looking at it now Figure 3B Only describe with Figure 3A The steps illustrated are new or modified compared to the steps shown.

[0059] In the optional conditional RFF blocking step 42, UE 2 determines whether the UE is configured to block RFF. This can be based, for example, on user configuration in the UE, or on interactive prompts using the user interface of the UE for each instance requesting the transmission of data for the RFF. If the UE is configured to block RFF, the method continues with obfuscation. Otherwise, the method continues to transmit specific UL data 46, but without applying any obfuscation.

[0060] In the optional privacy request step 43, UE 2 sends privacy request 21 to network node 1 to remove all RFF data used by UE 2.

[0061] In the optional privacy request receiving step 143, radio network node 1 receives privacy request 21 and removes the RFF data for UE 2. In this way, for greater privacy of the UE, the network has removed the association between the RFF parameters and UE 2.

[0062] In the optional step 44 of determining one or more obfuscation parameters, UE 2 determines at least one parameter for obfuscating hardware-specific identification information. This step may optionally be part of sending specific UL data 46, but may also be separated to determine the aforementioned obfuscation parameters.

[0063] Looking at it now Figure 3C Only describe with Figure 3B The steps illustrated are new or modified compared to the steps shown.

[0064] In the optional step 48 of sending user UL data, UE 2 sends an uplink transmission including user data 23 while applying at least one parameter (i.e., applying obfuscation). This can be applied to all UL transmissions to prevent the user from being tracked by passive RFF identification methods.

[0065] In the optional step 148 of receiving user UL data, radio network node 1 receives user UL data 23. Because obfuscation is also applied to UL user data 23, radio network node 1 cannot perform an RFF based on UL user data 23.

[0066] Figure 4 The illustration is based on one embodiment. Figure 1 A schematic diagram of some components of UE 2. The processing circuitry 60 is provided using any combination of one or more of a suitable central processing unit (CPU), graphics processing unit (GPU), multiprocessor, neural processing unit (NPU), microcontroller, digital signal processor (DSP), etc., capable of executing software instructions 67 stored in memory circuitry 64. Therefore, memory circuitry 64 can be a computer program product. The processing circuitry 60 can alternatively be implemented using application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), etc. The processing circuitry 60 can be configured to execute the above-referenced... Figures 3A-3C The method described for UE 2.

[0067] The memory circuit 64 can be any combination of random access memory (RAM) and / or read-only memory (ROM). The memory circuit 64 also includes a non-transitory persistent storage device, which can be any or a combination of magnetic storage, optical storage, solid-state storage, or even remotely mounted storage.

[0068] A data memory 66 is also provided for reading and / or storing data during the execution of software instructions in the processing circuitry 60. The data memory 66 can be any combination of RAM and / or ROM.

[0069] An I / O interface 62 is provided for communicating with external and / or internal entities using wireless communication (such as Wi-Fi, Bluetooth, Bluetooth Low Energy, and / or cellular networks compliant with sixth-generation (6G) mobile networks, next-generation mobile networks (fifth-generation, 5G), LTE (Long Term Evolution), UMTS (Universal Mobile Telecommunications System) utilizing W-CDMA (Wideband Code Division Multiple Access), or any other current or future wireless network, provided the principles described below apply). A transport chain 7 forms part of the I / O interface 62.

[0070] Other components of UE 2 have been omitted so as not to obscure the concepts presented herein.

[0071] Figure 5 This illustrates an embodiment. Figure 1 A schematic diagram of the functional modules of UE 2. These modules are implemented using software instructions such as computer programs executed within UE 2. Alternatively or additionally, the modules are implemented using hardware, such as any one or more of ASICs (Application-Specific Integrated Circuits), FPGAs (Field-Programmable Gate Arrays), or discrete logic circuits. The modules correspond to... Figures 3A-3C The steps in the method for UE 2 are illustrated in the figure.

[0072] UL Tx (transmission) request receiver 70 corresponds to step 40. RFF barrier determiner 72 corresponds to step 42. Privacy request sender 73 corresponds to step 43. Parameter determiner 74 corresponds to step 44. Specific UL data sender 76 corresponds to step 46. User UL data sender 78 corresponds to step 48.

[0073] Figure 6 An example of a computer program product 90 including a computer-readable device is shown. On this computer-readable device, a computer program 91 may be stored in non-transitory memory. The computer program can cause processing circuitry to perform methods according to the embodiments described herein. In this example, the computer program product 90 takes the form of a removable solid-state memory (e.g., a Universal Serial Bus (USB) drive). As explained above, the computer program product may also be embodied in the memory of a device (such as…). Figure 4The computer program 91 is shown herein as part of a removable solid-state storage device. However, the computer program may be stored in any manner suitable for the computer program product, such as another type of removable solid-state storage device, or an optical disc such as a CD (Compact Disc), DVD (Digital Versatile Disc), or Blu-ray Disc.

[0074] The aspects of this disclosure have been described above primarily with reference to some embodiments. However, as will be readily understood by those skilled in the art, other embodiments besides those disclosed above are also possible within the scope of the invention as defined by the appended claims. Therefore, although various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for illustrative purposes and are not intended to be limiting; the true scope is indicated by the following claims.

Claims

1. A method for obfuscating hardware-specific identification information of a user equipment (UE) (2) in a communication network (9) to prevent the UE from performing a radio frequency fingerprinting (RFF), the method being performed by the UE (2) configured to prevent the RFF, the method comprising: Upon receiving (40) a request (20) for sending specific uplink data; (46) Obfuscated uplink data (22) is sent to radio network node (1), the obfuscated uplink data (22) being constructed by applying at least one parameter to the specific uplink data for obfuscating hardware-specific identification information which may otherwise be used in the RFF of the UE (2) based on the uplink transmission of the UE (2).

2. The method according to claim 1, further comprising: It is determined (42) that the UE (2) is configured to block RFF.

3. The method according to claim 1 or 2, further comprising: Determine (44) the at least one parameter used to obfuscate hardware-specific identification information.

4. The method according to any one of the preceding claims, wherein, The request is an RFF-based authentication request issued by the radio network node (1).

5. The method according to any one of the preceding claims, wherein, The at least one parameter includes an offset for the at least one QAM symbol in one or both of the in-phase I component and the quadrature Q component.

6. The method according to any one of the preceding claims, wherein, The at least one parameter includes an offset for the bias used in the power amplifier or an offset for the power level.

7. The method according to any one of the preceding claims, wherein, The at least one parameter includes digital predistortion (DPD) parameters, which are determined to be mismatched with the power amplifiers used for uplink transmission of the UE.

8. The method according to any one of the preceding claims, wherein, The at least one parameter is determined based on a random number source or a pseudo-random number source.

9. The method according to any one of the preceding claims further comprises: When the at least one parameter is applied, an uplink transmission including user data is sent (48).

10. The method according to any one of the preceding claims further comprises: Send a privacy request (43) to the network node (1) to remove all RFF data used by the UE (2).

11. The method according to any one of the preceding claims, wherein, The communication network is a cellular network.

12. A user equipment (UE) (2) for obfuscating hardware-specific identification information of the UE to prevent the UE from performing radio frequency fingerprinting (RFF), the UE being configured to form part of a communication network (9), the UE (2) comprising: Processing circuit (60); as well as A memory circuit (64) storing instructions (67), which, when executed by the processing circuit, causes the UE (2) to: Upon receiving a request (20) for sending specific uplink data; Obfuscated uplink data (22) is sent to a radio network node (1). The obfuscated uplink data (22) has been constructed by applying at least one parameter to the specific uplink data for obfuscating hardware-specific identification information, which may otherwise be used in the RFF of the UE (2) based on the uplink transmission of the UE (2).

13. The UE (2) according to claim 12, further comprising an instruction (67), said instruction (67) causing the UE (2) to: when executed by said processing circuitry: It is determined that the UE (2) is configured to block RFF.

14. The UE (2) according to claim 12 or 13, further comprising an instruction (67) that, when executed by the processing circuitry, causes the UE (2) to: Determine at least one parameter used to obfuscate hardware-specific identification information.

15. The UE (2) according to any one of claims 12 to 14, wherein, The request is an RFF-based authentication request issued by the radio network node (1).

16. The UE (2) according to any one of claims 12 to 15, wherein, The at least one parameter includes an offset for the at least one QAM symbol in one or both of the in-phase I component and the quadrature Q component.

17. The UE (2) according to any one of claims 12 to 16, wherein, The at least one parameter includes an offset for the bias used in the power amplifier or an offset for the power back-off level.

18. The UE (2) according to any one of claims 12 to 17, wherein, The at least one parameter includes digital predistortion (DPD) parameters, which are determined to be mismatched with the power amplifiers used for uplink transmission of the UE.

19. The UE (2) according to any one of claims 12 to 18, wherein, The at least one parameter is determined based on a random number source or a pseudo-random number source.

20. The UE (2) according to any one of claims 12 to 19, further comprising an instruction (67) that, when executed by the processing circuitry, causes the UE (2) to: When the at least one parameter is applied, an uplink transmission including user data is sent.

21. The UE (2) according to any one of claims 12 to 20, further comprising an instruction (67) that, when executed by the processing circuitry, causes the UE (2) to: Send a privacy request to the network node (1) to remove all RFF data used by the UE (2).

22. The UE (2) according to any one of claims 12 to 21, wherein, The communication network is a cellular network.

23. A computer program (67, 91) for obfuscating hardware-specific identification information of a user equipment (UE) (2) in a communication network (9) to prevent the UE from performing radio frequency fingerprinting (RFF), the computer program comprising computer program code that, when executed on the UE (2), causes the UE (2) to: Upon receiving a request (20) for sending specific uplink data; Obfuscated uplink data (22) is sent to a radio network node (1). The obfuscated uplink data (22) has been constructed by applying at least one parameter to the specific uplink data for obfuscating hardware-specific identification information, which may otherwise be used in the RFF of the UE (2) based on the uplink transmission of the UE (2).

24. A computer program product (64, 90) comprising the computer program of claim 23 and a computer-readable means, the computer-readable means comprising a non-transitory memory in which the computer program is stored.

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