Wireless communication device, communication system, wireless communication method, and program

Abstract

This invention aims to realize a wireless communication device that can identify a base station with high accuracy simply by receiving radio waves from the base station, without requiring any modification of the communication protocol. [Solution] The wireless communication device 100 identifies a base station based on eigenvalue statistics derived from a CSI matrix, which accurately reflect the unique hardware characteristics of the base station's antenna. Therefore, the wireless communication device 100 can identify base stations with high accuracy, and for example, by analyzing the base station identification results, it can detect fraudulent base stations operated by third parties with high accuracy. Furthermore, since the wireless communication device 100 only needs to receive radio waves from the base station and obtain eigenvalue statistics derived from the CSI matrix, it does not require modification of the communication protocol. Therefore, the wireless communication device 100 can identify base stations with high accuracy simply by receiving radio waves from the base station, without requiring any modification of the communication protocol.

Description

[Technical Field]

[0001] This invention relates to a technology for identifying base stations used in mobile communication systems and communication networks that realize high-speed, high-capacity communication. [Background technology]

[0002] The fifth-generation mobile communication system (5G), which has been put into practical use in recent years, enables high-speed, high-capacity communication, low latency, and massive connectivity. Standardization has been implemented to allow many telecommunications carriers and users to utilize 5G networks, and the open-sourcing of 5G networks is being promoted. With the opening up of 5G networks, the implementation of 5G systems using open source is progressing. Therefore, it has become relatively easy to test the functions of base stations and other equipment installed in 5G networks, and various security challenges are becoming more real. Among these, the threat of unauthorized base stations has been frequently pointed out, and countermeasures are desired.

[0003] For example, Non-Patent Document 1 discloses a technology that uses location information to identify fraudulent base stations. Specifically, in the technology described in Non-Patent Document 1, a communication device attempting to perform a handover estimates the location of a base station and compares it with a registration list held by the network. If the base station is not registered in the registration list, it is determined (identified) as a fraudulent base station.

[0004] Furthermore, Non-Patent Document 2 discloses a technology for detecting (identifying) fraudulent base stations by encrypting the Resource Block ID. Specifically, in the technology of Non-Patent Document 2, a legitimate communication device (User Equipment: UE) and a base station share a common key, and the legitimate base station encrypts the assigned resource block ID (RB ID) with authentication and transmits it to the legitimate UE. The legitimate UE decrypts the encrypted data received from the base station, and if it cannot obtain the correct ID (RB ID) through decryption, it determines that the base station is fraudulent. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] 3GPP TR33.809, "Study on 5G security enhancements against False Base Stations (FBS)," (2023 / 6) [Non-Patent Document 2] David Rupprecht, Katharina Kohls, Thorsten Holz, Christina Poepper, IMP4GT: IMPersonation Attacks in 4G NeTworks, Network and Distributed Systems Security (NDSS) Symposium 2020, 23-26 (2020 / 2) [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] While the above-mentioned prior art (technologies described in Non-Patent Documents 1 and 2) can detect (determine) unauthorized base stations, it involves modifying communication protocols, and there is a problem in that extensive work such as standardization is required to make such technologies usable.

[0007] Therefore, in view of the above problems, the present invention aims to realize a wireless communication device, communication system, wireless communication method, and program that can identify a base station with high accuracy simply by receiving radio waves from the base station (by a passive method), without requiring any modification of the communication protocol. [Means for solving the problem]

[0008] To solve the above problems, a representative example (one aspect) of the invention disclosed in this application is a wireless communication device capable of receiving wireless communication signals from a base station that transmits a wireless communication signal obtained by performing data modulation on a symbol consisting of one or more bit sequences using multiple subcarriers, and performing RF modulation on the baseband modulated signal, comprising an RF demodulation processing unit, a BB demodulation processing unit, and a base station identification unit.

[0009] The RF demodulation processing unit obtains a baseband demodulated signal by performing RF demodulation processing on the wireless communication signal transmitted from the base station.

[0010] The BB demodulation processing unit performs baseband demodulation processing on the baseband demodulated signal to acquire the symbols corresponding to the transmitted symbols, which are data-modulated symbols at the base station, as demodulated symbols.

[0011] The base station identification unit obtains the frequency response characteristics for each subcarrier based on the transmission symbol and demodulation symbol, obtains a CSI matrix based on the obtained frequency response characteristics, and performs base station identification processing, which identifies the base station based on the statistical values ​​of the eigenvalues ​​derived from the obtained CSI matrix. [Effects of the Invention]

[0012] According to the present invention, a wireless communication device, communication system, wireless communication method, and program can be realized that identify a base station with high accuracy simply by receiving radio waves from the base station (by a passive method), without requiring any modification of the communication protocol. [Brief explanation of the drawing]

[0013] [Figure 1] A schematic diagram of the communication system 1000 according to the first embodiment. [Figure 2] A schematic diagram of the base station BSi used in the communication system 1000 according to the first embodiment. [Figure 3]A schematic diagram of the wireless communication device 100 according to the first embodiment. [Figure 4] A schematic diagram of the BB demodulation processing unit 2 of the wireless communication device 100 according to the first embodiment. [Figure 5] A schematic diagram showing the resource block (OFDM resource block) for the communication method adopted in communication system 1000 (a diagram showing the arrangement of pilot symbols and data symbols in the resource block). [Figure 6] A flowchart of the process performed by the wireless communication device 100 of the communication system 1000. [Figure 7] This diagram schematically shows the resource block (OFDM resource block) based on the communication method adopted by the transmitting and receiving communication system 1000 (a diagram showing the arrangement of pilot symbols and data symbols in the resource block). [Figure 8] A diagram showing the transmitted complex symbol X(i) k,t and the received complex symbol Y(i) k,t on the complex plane. [Figure 9] The figure shows the results of base station identification processing using the base station identification processing method of the present invention (a base station identification processing method using the top Nbest variance values ​​of eigenvalues ​​derived from the CSI matrix) and the results of base station identification processing using the phase difference detection method (a method for obtaining the variance value of the phase difference of the phase characteristics of the frequency response characteristics of each subcarrier between the base station BSi and the wireless communication device 100). [Figure 10] A schematic diagram of the communication system 1000A according to the first modified example of the first embodiment. [Figure 11] A schematic diagram of the wireless communication device 100A according to the first modified example of the first embodiment. [Figure 12] A schematic diagram of the user terminal UEi according to the first modified example of the first embodiment. [Figure 13] A diagram showing the CPU bus configuration. [Modes for carrying out the invention]

[0014] [First Embodiment] The first embodiment will be described below with reference to the drawings.

[0015] <1.1: Communication System Configuration> Figure 1 is a schematic diagram of the communication system 1000 according to the first embodiment.

[0016] Figure 2 shows the base station BS used in the communication system 1000 according to the first embodiment. i This is a schematic diagram of the system.

[0017] Figure 3 is a schematic diagram of the wireless communication device 100 according to the first embodiment.

[0018] Figure 4 is a schematic diagram of the BB demodulation processing unit 2 of the wireless communication device 100 according to the first embodiment.

[0019] Communication system 1000 is a mobile communication system that realizes high-speed and high-capacity communication, such as a fifth-generation mobile communication system (5G). Figure 1 shows the base station BS used in communication system 1000. i (i: natural number, 1 ≤ i ≤ Nb, Nb: natural number) and the user terminal UE j This diagram schematically shows (j: natural number, 1 ≤ j ≤ M, M: natural number) and wireless communication device 100 (wireless communication device).

[0020] For the sake of explanation, the communication system 1000 is a communication system that realizes mobile communication using a digital modulation scheme (for example, the OFDM scheme (OFDM: Orthogonal Frequency-Division Multiplexing)), and the wireless communication device 100 is a communication system that enables mobile communication using multiple base stations BS. i Assuming that the system is positioned to communicate with (i: a natural number, 1 ≤ i ≤ N, N: a natural number), and that mobile communication is realized in the communication system 1000 using the OFDM digital modulation scheme, the following explanation will be provided.

[0021] As shown in Figure 1, the communication system 1000 consists of N base stations BS. i(i: natural number, 1 ≦ i ≦ Nb, Nb: natural number), and M user terminals UE j (j: natural number, 1 ≦ j ≦ Me, Me: natural number), and a wireless communication device 100 are provided.

[0022] (1.1.1: Configuration of base station) Nb base stations BS i (i: natural number, 1 ≦ i ≦ Nb, Nb: natural number) each have a function capable of performing communication by the OFDM method, and have a function of digitally modulating data and further RF-modulating a wireless communication signal (radio wave) and transmitting it to the outside via an antenna Ant_BS.

[0023] Base station BS i As shown in FIG. 2, it includes an S / P conversion unit B1, a symbol mapping processing unit B2, an inverse FFT processing unit B3, an RF modulation processing unit B4, and an antenna Ant_BS. In FIG. 2, only the functional units of the data transmission system of the base station BS are illustrated, and the functional units of the data reception system and other functional units of the base station BS are omitted from the illustration. i of the base station BS i of the base station BS

[0024] The S / P conversion unit B1 inputs data Din_tx (serial data (bit string)), performs serial-parallel conversion on the data Din_tx, and obtains symbol sequence data (parallel data) Stx0 to Stx N-1 (N: number of symbols, N: natural number) by allocating the bit string segmented by a predetermined number of bits to a predetermined symbol. Then, the S / P conversion unit B1 outputs the obtained symbol sequence data (parallel data) Stx0 to Stx N-1 to the symbol mapping processing unit B2.

[0025] The symbol mapping processing unit B2 inputs the symbol sequence data (parallel data) Stx0 to Stx N-1 input from the S / P conversion unit B1. The symbol mapping processing unit B2 inputs the symbol sequence data (parallel data) Stx0 to Stx N-1For each of these, a symbol mapping process (for example, QAM (Quadrature Amplitude Modulation), PSK (Phase Shift Keying) modulation process) is performed, and the complex symbol sequence X0~X N-1 The symbol mapping processing unit B2 then obtains the obtained complex symbol sequence X0~X N-1 The output is sent to the inverse FFT processing unit B3.

[0026] The inverse FFT processing unit B3 outputs the complex symbol sequence X0~X from the symbol mapping processing unit B2. N-1 Input the following. The inverse FFT processing unit B3 processes the complex symbol sequence X0~X N-1 Perform an inverse Fourier transform (for example, an inverse fast Fourier transform (FFT)) on the complex symbol sequence X i The baseband OFDM signals SigI_bb_tx (I-phase component signal (I-phase component (in-phase component): In-phase component)) and SigQ_bb_tx (Q-phase component signal (Q-phase component (quadrature-phase component): Quadrature-phase component)) are obtained by superimposing all the signals digitally modulated with the carrier wave of the subcarrier frequency (digital modulated signals for each subcarrier frequency). The inverse FFT processing unit B3 then outputs the obtained baseband OFDM signals SigI_bb_tx and SigQ_bb_tx to the RF modulation processing unit B4.

[0027] The RF modulation processing unit B4 receives the baseband OFDM signals SigI_bb_tx and SigQ_bb_tx output from the inverse FFT processing unit B3, and performs RF modulation on the baseband OFDM signals SigI_bb_tx and SigQ_bb_tx to obtain the carrier band OFDM signal Sig_rf_tx. Then, the RF modulation processing unit B4 transmits the obtained carrier band OFDM signal Sig_rf_tx to the outside via the antenna Ant_BS (radiates radio waves (wireless communication signals)).

[0028] (1.1.2: Configuration of the wireless communication equipment) The wireless communication device 100 has the capability to perform communication using the OFDM method, and the base station BS i The wireless communication signal (radio wave) transmitted from the base station is received via the antenna Ant_rx, and the received signal is demodulated using RF demodulation and BB demodulation before being processed by the base station BS. i It has the function of receiving data transmitted from the base station. Furthermore, the wireless communication device 100 has the function of performing a process to identify the base station.

[0029] As shown in Figure 3, the wireless communication device 100 comprises an RF demodulation processing unit 1, a BB demodulation processing unit 2, a base station identification unit 3, and a data processing unit 4. Note that Figure 3 only shows the data receiving system functions of the wireless communication device 100; the data transmission system functions and other functions of the wireless communication device 100 are not shown.

[0030] The RF demodulation processing unit 1 is located at the base station BS. i The radio communication signal (radio wave) transmitted from is received as the signal Sig_rf_rx via the antenna Ant_rx, and RF demodulation processing is performed on the received signal Sig_rf_rx to obtain the baseband I-phase component signal SigI_bb_rx (I-phase component (in-phase component)) and the baseband Q-phase component signal SigQ_bb_rx (Q-phase component (quadrature-phase component)). The RF demodulation processing unit 1 then outputs the obtained baseband I-phase component signal SigI_bb_rx and baseband Q-phase component signal SigQ_bb_rx to the BB demodulation processing unit 2.

[0031] The BB demodulation processing unit 2 is a functional unit that receives the baseband I-phase component signal SigI_bb_rx and the baseband Q-phase component signal SigQ_bb_rx output from the RF demodulation processing unit 1 and performs baseband demodulation processing (BB demodulation processing) on ​​these signals. As shown in Figure 4, the BB demodulation processing unit 2 comprises an FFT processing unit 21, a symbol detection processing unit 22, and a P / S conversion unit 23.

[0032] The FFT processing unit 21 receives the baseband I-phase component signal SigI_bb_rx and the baseband Q-phase component signal SigQ_bb_rx output from the RF demodulation processing unit 1, and performs FFT processing (for example, FFT (Fast Fourier Transform)) on the baseband I-phase component signal SigI_bb_rx and the baseband Q-phase component signal SigQ_bb_rx, and generates a complex symbol sequence Y0~Y N-1 The FFT processing unit 21 then obtains the complex symbol sequence Y0~Y N-1 This is output to the base station identification unit 3 and the symbol detection processing unit 22. Note that the complex symbol sequence Y0~Y N-1 Let the data containing this be Data D1.

[0033] The symbol detection processing unit 22 processes the complex symbol sequence Y0~Y output from the FFT processing unit 21. N-1 Enter the following, and the complex symbol sequence Y0~Y N-1 For this, a symbol detection process is performed, and the symbol sequence Srx0~Srx N-1 The symbol detection processing unit 22 then retrieves the acquired symbol sequence Srx0~Srx N-1 This is output to the P / S conversion unit 23.

[0034] The P / S conversion unit 23 outputs the symbol sequence Srx0~Srx from the symbol detection processing unit 22. N-1 Enter the symbol sequence Srx0~Srx N-1 The P / S conversion unit 23 then performs a parallel-to-serial conversion to obtain serial data D2. The P / S conversion unit 23 then outputs the obtained data D2 to the data processing unit 4.

[0035] As shown in Figure 3, the base station identification unit 3 comprises a CSI matrix acquisition processing unit 31, an eigenvalue acquisition processing unit 32, a high-principal component variance acquisition processing unit 33, and a base station identification processing unit 34.

[0036] The CSI matrix acquisition processing unit 31 receives data D1 output from the BB demodulation processing unit 2 and control signal CTL1 output from the control unit (not shown) that controls the functional parts of the wireless communication device 100. Based on the control signal CTL1, it executes a process to acquire the CSI matrix (CSI: channel state information) from data D1 (CSI matrix acquisition process) and acquires the CSI matrix data (CSI matrix data). The CSI matrix acquisition processing unit 31 then outputs the data including the acquired CSI matrix data as data D11 to the eigenvalue acquisition processing unit 32.

[0037] The eigenvalue acquisition processing unit 32 receives data D11 output from the CSI matrix acquisition processing unit 31, and performs an eigenvalue acquisition process (eigenvalue acquisition process) based on data D11 to obtain eigenvalue data. Then, the eigenvalue acquisition processing unit 32 outputs the data including the acquired eigenvalue data as data D12 to the upper principal component variance acquisition processing unit 33.

[0038] The upper principal component variance acquisition processing unit 33 receives the data D12 output from the eigenvalue acquisition processing unit 32, and performs a process to acquire the variance of the upper principal components (upper principal component variance acquisition process) based on the data D12, thereby obtaining the upper principal component variance data. Then, the upper principal component variance acquisition processing unit 33 outputs the data including the acquired upper principal component variance data as data D13 to the base station identification processing unit 34.

[0039] The base station identification processing unit 34 receives the data D13 output from the upper principal component variance acquisition processing unit 33, performs a base station identification process (base station identification process) based on the data D13, and obtains base station identification process result data. The base station identification processing unit 34 then outputs the data including the obtained base station identification process result data as data Dout.

[0040] The data processing unit 4 receives the data D2 output from the BB demodulation processing unit 2 and performs predetermined data processing on the data D2.

[0041] (1.1.3: User terminal) User Terminal UE j (j: natural number, 1 ≤ j ≤ Me, Me: natural number) Each of these has the capability to perform communication using the OFDM method, and the base station BS i The base station receives wireless communication signals (radio waves) transmitted from the base station via an antenna, and demodulates the received signals using RF demodulation and BB demodulation. i It has the function of receiving data transmitted from the user terminal UE. j (j: natural number, 1 ≤ j ≤ Me, Me: natural number) each has a configuration that includes functional units similar to the antenna Ant_rx, RF demodulation processing unit 1, BB demodulation processing unit 2, and data processing unit 4 of the wireless communication device 100.

[0042] <1.2: Operation of the communication system> The operation of the communication system 1000 configured as described above will be explained below with reference to the diagrams.

[0043] Figure 5 is a schematic diagram showing the resource block (OFDM resource block) according to the communication method adopted in the communication system 1000 (a diagram showing the arrangement of pilot symbols and data symbols in the resource block).

[0044] Figure 6 is a flowchart of the processes performed by the wireless communication device 100 of the communication system 1000.

[0045] Figure 7 is a schematic diagram showing the resource block (OFDM resource block) according to the communication method adopted by the transmitting and receiving communication system 1000 (a diagram showing the arrangement of pilot symbols and data symbols in the resource block).

[0046] Figure 8 shows the transmitted complex symbol X on the complex plane. (i) k,t The complex symbol Y received (i) k,t This is a diagram illustrating that.

[0047] Figure 9 shows the base station identification processing method of the present invention (the top N eigenvalues ​​derived from the CSI matrix). best This figure shows the base station identification processing result data using the base station identification processing method (based on individual variance values) and the base station identification processing result data using the phase difference detection method (a method for obtaining the variance value of the phase difference of the phase characteristics of the frequency response characteristics of each subcarrier between the base station BSi and the radio communication device 100).

[0048] The operation of the communication system 1000 will be explained below, with reference to the flowchart in Figure 6.

[0049] For the sake of explanation, as shown in Figure 1, the communication system 1000 has Nb base stations BS. i (i: natural number, 1 ≤ i ≤ Nb, Nb: natural number) and there exist wireless communication devices 100 with Nb base stations BS i This section explains the case where radio waves (wireless communication signals) from a base station (BS) can be received (one example). It also describes the case of Nb base stations (BS). i The OFDM system shall emit radio waves (transmit a wireless communication signal) including a pilot signal (a signal transmitted at a fixed frequency and time (a known signal (a signal for transmitting a pilot symbol))) in the OFDM signal.

[0050] Specifically, base station BS i The OFDM system transmits a pilot signal (a signal transmitted at a fixed frequency and time (a known signal (a signal for transmitting a pilot symbol))) by performing the following process.

[0051] base station BS i At a predetermined timing, the system sets data containing pilot symbols (known data) as data Din_tx and inputs this data Din_tx to the S / P conversion unit B1. The S / P conversion unit B1 performs serial-to-parallel conversion on the data Din_tx (serial data (bit sequence)) and assigns the bit sequence, divided into predetermined numbers of bits, to predetermined symbols to obtain symbol sequence data (parallel data) Stx0~Stx. N-1The (N: number of symbols, N: natural number) is obtained. Then, the S / P conversion unit B1 converts the obtained symbol sequence data (parallel data) Stx0~Stx N-1 Output to symbol mapping processing unit B2.

[0052] base station BS i The symbol mapping processing unit B2 receives the symbol sequence data (parallel data) Stx0~Stx from the S / P conversion unit B1. N-1 For each of these, a symbol mapping process (for example, QAM (Quadrature Amplitude Modulation), PSK (Phase Shift Keying) modulation process) is performed, and the complex symbol sequence X0~X N-1 The symbol mapping processing unit B2 then obtains the obtained complex symbol sequence X0~X N-1 The output is sent to the inverse FFT processing unit B3.

[0053] The inverse FFT processing unit B3 outputs the complex symbol sequence X0~X from the symbol mapping processing unit B2. N-1 Perform an inverse Fourier transform (for example, an inverse fast Fourier transform (inverse FFT (inverse fast Fourier transform), FFT: Fast Fourier Transform)) on the complex symbol sequence X i The baseband OFDM signals SigI_bb_tx (I-phase component signal (I-phase component (in-phase component): In-phase component)) and SigQ_bb_tx (Q-phase component signal (Q-phase component (quadrature-phase component): Quadrature-phase component)) are obtained by superimposing all the signals digitally modulated with the carrier wave of the subcarrier frequency (digital modulated signals for each subcarrier frequency). The inverse FFT processing unit B3 then outputs the obtained baseband OFDM signals SigI_bb_tx and SigQ_bb_tx to the RF modulation processing unit B4.

[0054] The RF modulation processing unit B4 performs RF modulation on the baseband OFDM signals SigI_bb_tx and SigQ_bb_tx output from the inverse FFT processing unit B3 to obtain the carrier band OFDM signal Sig_rf_tx. Then, the RF modulation processing unit B4 transmits the obtained carrier band OFDM signal Sig_rf_tx to the outside via the antenna Ant_BS (radiates radio waves (wireless communication signals)).

[0055] The pilot symbol is determined by the communication method adopted by the communication system 1000, and for example, as shown in Figure 5, it is placed in a predetermined position (a position determined by the communication method adopted by the communication system 1000) in the resource block. In the case of Figure 5, the number of OFDM symbols constituting the resource block is N. syn (N syn N is a natural number, and the number of carriers (subcarriers) is N. sc (N sc : Natural number) (For example, N sc =N(N sc (This may be made to match the number of elements N in the complex symbol sequence), and the pilot symbol is placed in the symbol of the third OFDM at a position corresponding to the even-numbered subcarrier.

[0056] In the following explanation, for the sake of clarity, we will describe an example where the pilot symbol is arranged in the resource block as shown in Figure 5. Note that the arrangement of the pilot symbol within the resource block is determined by the communication method and may differ from the example shown in Figure 5.

[0057] (Step S101): In step S101, loop 1 processing (the first loop processing) begins. Loop 1 processing is executed for each time step t (t: integer, 1 ≤ t ≤ T, T: natural number) (it is executed for each time step t, incrementing t by +1 from t=1 until t=T (during the period from t=1 to t=T)).

[0058] (Step S102): In step S102, loop 2 processing (second loop processing) is started. Loop 2 processing involves each base station BS from which the wireless communication device 100 can receive radio waves. i For (i: integer, 1 ≤ i ≤ Nb, Nb: natural number), the execution is performed (incrementing i by +1 from i=1 until i=Nb, at each base station BS) i (This will be performed on each base station BS from which the wireless communication device 100 can receive radio waves.) i Assuming there are Nb such base stations, these Nb base stations are designated as BS1 to BS Nb The following will be explained (the wireless communication device 100 is connected to base stations BS1~BS Nb (It is assumed that the radio waves emitted from each of these sources are in a state where they can be received.)

[0059] (Step S103): In step S103, the reception process is executed. Specifically, the following processes are performed.

[0060] The wireless communication device 100 receives radio waves (wireless communication signals) radiated from base station BS1 (i=1) as the signal Sig_rf_rx via the antenna Ant_rx.

[0061] The RF demodulation processing unit 1 of the wireless communication device 100 performs RF demodulation processing on the received signal Sig_rf_rx (a wireless communication signal transmitted from base station BS1) to obtain the baseband I-phase component signal SigI_bb_rx (I-phase component (in-phase component)) and the baseband Q-phase component signal SigQ_bb_rx (Q-phase component (quadrature-phase component)). The RF demodulation processing unit 1 then outputs the obtained baseband I-phase component signal SigI_bb_rx and baseband Q-phase component signal SigQ_bb_rx to the BB demodulation processing unit 2.

[0062] The FFT processing unit 21 of the BB demodulation processing unit 2 of the wireless communication device 100 performs FFT processing (for example, FFT (Fast Fourier Transform)) on the baseband I-phase component signal SigI_bb_rx and the baseband Q-phase component signal SigQ_bb_rx output from the RF demodulation processing unit 1, and generates a complex symbol sequence Y0~Y N-1 To obtain the complex symbol sequence Y0~Y, a complex signal is generated with the real part being the baseband I-phase component signal SigI_bb_rx and the imaginary part being the baseband Q-phase component signal SigQ_bb_rx, and an FFT (Fast Fourier Transform) is performed on this complex signal. N-1 (Obtains) Then, the FFT processing unit 21 processes the obtained complex symbol sequence Y0~Y N-1 The data containing this information is output to the base station identification unit 3 as data D1.

[0063] (Step S104): In step S104, the CSI matrix acquisition process is executed. Specifically, the following processes are performed.

[0064] The CSI matrix acquisition processing unit 31 of the base station identification unit 3 executes a process (CSI matrix acquisition process) to acquire the CSI matrix (CSI: channel state information) from the data D1 output from the BB demodulation processing unit 2.

[0065] Specifically, the CSI matrix acquisition processing unit 31 uses pilot symbols obtained from the data received by the wireless communication device 100 to obtain estimated values ​​of the transfer function for each carrier (subcarrier). When the resource block shown in Figure 5 (resource block for OFDM) is used, as shown in Figure 7, at time step t, (1) base station BS i The pilot symbol for the second OFDM symbol of the data sent from (resource block for OFDM) is {X (i) 1,t ,X (i) 1,t ,X (i) 2,t ,X (i) 3,t ,···,X (i) K,t} and the data corresponding to the pilot symbol (demodulated pilot symbol) obtained from the data received by the wireless communication device 100 is {Y (i) 1,t , Y (i) 1,t , Y (i) 2,t , Y (i) 3,t , ···, Y (i) K,t}. In this case, the CSI matrix acquisition processing unit 31 specifies the timing at which the above demodulated pilot symbol can be acquired according to the control signal CTL1 output from a control unit (not shown) that controls the functional units of the wireless communication device 100, and acquires the above demodulated pilot symbol at the specified timing. Then, the CSI matrix acquisition processing unit 31 H (i) k,t = Y (i) k,t / X (i) k,t H (i) k,t : Estimated value of transfer function k = int[k sc / 2] + 1 (k sc : Sub - carrier number, k: integer, 1 ≤ k ≤ K, K: integer, K = int[(N sc - 1) / 2] + 1, N sc : Number of carriers (sub - carriers)) t: Time step (t: integer, 1 ≤ t ≤ T, T: integer) i: Base station number (i: integer, 1 ≤ i ≤ T, T: integer) By performing the processing corresponding to, the estimated value H of the transfer function (i) K,t is obtained.

[0066] Note that X (i) K,tX is a pilot symbol and is a known complex symbol (complex number) (data obtained by mapping a bit sequence (symbol) of a predetermined number of bits to a predetermined point on the complex plane (mapping data that follows a signal point arrangement (constellation) determined by a digital modulation scheme (e.g., QPSK, 64QAM, 256QAM, etc.))) (The CSI matrix acquisition processing unit 31 receives the pilot symbol X, which is a known complex symbol. (i) K,t (Assume that the data of Y is held (or can be retrieved). (i) K,t is a base station BS i Since this is demodulated data obtained by the wireless communication device 100 through demodulation processing of the signal transmitted from, for example, as shown in Figure 8, the original data (X) is in the complex plane. (i) K,t The phase shifts from ) and / or the amplitude changes. (i) K,t and Y (i) K,t Since it is a complex symbol (complex number), H (i) k,t =Y (i) k,t / X (i) k,t This allows us to obtain an estimated value of the transfer function (a complex number) (an estimated value of the transfer function of the subcarrier (channel) corresponding to k at time step t (an estimated value of the channel frequency response)).

[0067] Furthermore, if the pilot symbol placement pattern differs in the OFDM resource block, the demodulated pilot symbol is obtained according to that placement pattern, and the transfer function estimate H is obtained by the same process as above. (i) k,t You just need to get it.

[0068] The CSI matrix acquisition processing unit 31 performs the above process for k=1 to k=K, thereby H (i) 1,t ~H (i) K,tThe CSI matrix acquisition processing unit 31 then obtains the acquired data into a vector H. (i) t It is kept as follows: That is, the CSI matrix acquisition processing unit 31 uses the following formula H (i) t It stores and retains that information.

number

[0069] (Step S105): In step S105, the termination of loop 2 processing is determined. That is, all base stations BS from which the wireless communication device 100 can receive radio waves are checked. i If it is determined that loop 2 processing has been executed, the process proceeds to step S106, while all base stations BS from which the wireless communication device 100 can receive radio waves are checked. i If it is determined that loop 2 processing has not been executed, the variable i is incremented by +1, the process returns to step S102, and loop 2 processing is repeatedly executed.

[0070] (Step S106): In step S106, the completion of loop 1 processing is determined. That is, if it is determined that loop 1 processing has been executed from time step t=1 to t=T, the process proceeds to step S107. On the other hand, if it is determined that loop 1 processing has not been executed from time step t=1 to t=T, the process returns to step S101, and loop 1 processing is executed in the next time step (the time step incremented by +1).

[0071] Furthermore, when the processing in step S106 is completed (when the loop 1 processing and loop 2 processing are completed), the CSI matrix acquisition processing unit 31 will perform the following actions for each base station BS i CSI matrix H (i) It obtains the following. In other words, the CSI matrix acquisition processing unit 31 obtains the base station BS, which is represented by the following formula. i CSI matrix H (i) They have obtained it.

number

[0072] (Step S108): In step S108, the eigenvalue acquisition process is executed. Specifically, the following processes are performed.

[0073] The CSI matrix acquisition processing unit 31 acquires the base station BS through loop 1 processing. i CSI matrix H (i) The data containing this information is output to the eigenvalue acquisition processing unit 32 as data D11.

[0074] The eigenvalue acquisition processing unit 32 performs the process of acquiring eigenvalues ​​using data D11.

[0075] Specifically, the eigenvalue acquisition processing unit 32 performs the following processing.

[0076] The eigenvalue acquisition processing unit 32 generates a column vector H whose elements are the estimated transfer function values ​​for each subcarrier at time step t. t (i) We obtain the covariance matrix for this.

number

number

number

number

[0077] The eigenvalue acquisition processing unit 32 then outputs the data containing the eigenvalue data set Dset_λ acquired above as data D12 to the upper principal component variance acquisition processing unit 33.

[0078] (Step S109): In step S109, the process of obtaining the top principal component variance is executed. Specifically, the following process is performed.

[0079] The upper principal component variance acquisition processing unit 33 calculates the eigenvalue data set Dset_λ(={λ1 (i) ,λ2 (i) ,···,λ K (i) For each data point (each eigenvalue) in}), perform the following process equivalent to the formula below, and the absolute value of the eigenvalue a j (i) Obtain it.

number

number

[0080] Then, the upper principal component variance acquisition processing unit 33 processes the upper principal component variance value V obtained as described above. (i) The data containing this information is output to the base station identification processing unit 34 as data D13.

[0081] (Step S110): In step S110, the termination of loop 3 processing is determined. That is, all base stations BS from which the wireless communication device 100 can receive radio waves are checked. i If it is determined that loop 3 processing has been executed, the process proceeds to step S111, while the wireless communication device 100 can receive radio waves from all base stations BS. iIf it is determined that loop 3 processing has not been executed, the variable i is incremented by +1, the process returns to step S107, and loop 3 processing is repeatedly executed.

[0082] (Step S111): In step S111, base station identification processing is performed. Specifically, the following processing is performed.

[0083] The base station identification processing unit 34 receives data D13 (higher principal component variance value V) output from the upper principal component variance acquisition processing unit 33. (i) Based on the data (including the above), the base station identification process (base station identification process) is performed. The base station identification processing unit 34 identifies all base stations BS from which the wireless communication device 100 can receive radio waves. i The upper principal component variance V for (i: integer, 1 ≤ i ≤ Nb) (i) It obtains the upper principal component variance value V. (i) The data set Dset_V (shown below) is being retrieved. Dset_V={V (1) ,V (2) ,···,V (Nb)} Nb: Number of base stations from which the wireless communication device 100 can receive radio waves. The base station identification processing unit 34 can identify a base station by recognizing the distribution of each element in the data set Dset_V. Furthermore, based on the base station identification result obtained by the base station identification processing unit 34, it can identify (determine) a fraudulent base station by, for example, performing time-series analysis. Then, the base station identification processing unit 34 processes the base station identification processing result data (upper principal component variance value V) obtained by the above processing. (i) The data set Dset_V, and / or the base station identification result data based on the data set Dset_V, are output as data Dout.

[0084] As described above, the wireless communication device 100 can perform base station identification processing. The wireless communication device 100 obtains a CSI matrix that shows the transmission characteristics (transfer function for each subcarrier) between the wireless communication device 100 and each base station from which the wireless communication device 100 can receive radio waves, and uses the CSI matrix to obtain eigenvalues ​​by eigenvalue decomposition processing. Then, the wireless communication device 100 obtains the top N of the eigenvalues. best The base station is identified by its individual variance values. The eigenvalues ​​for each base station derived from the CSI matrix reflect the unique hardware characteristics of the base station's antenna, so the top N eigenvalues best The variance values ​​obtained from each individual (upper principal component variance V) (i) This value allows for sensitive detection of even subtle differences in the hardware characteristics specific to the base station's antenna. Therefore, by performing the above-described base station identification process, the wireless communication device 100 can recognize (identify) the base station with extremely high sensitivity (high accuracy).

[0085] Furthermore, by processing the result data obtained from the base station identification process in chronological order, it becomes possible to accurately detect, for example, an unauthorized base station when it appears.

[0086] Figure 9 shows the base station identification processing method of the present invention (the top N eigenvalues ​​derived from the CSI matrix). best The data obtained from the base station identification process using the base station identification processing method based on the individual variance values, and the phase difference detection method (base station BS iFigure 9 shows the base station identification processing result data obtained by a method of acquiring the variance value of the phase difference of the phase characteristics of the frequency response characteristics of each subcarrier between the radio communication device 100 and the base station. Note that at times t0 to t4, the base stations that the radio communication device 100 can receive are BS1 to BS7, and at time t4, the radio waves of base station BS6 are interfered with (the radio waves to the radio communication device 100 are blocked), and instead, an unauthorized base station is installed within range to communicate with the radio communication device 100. Also, in Figure 9, the data acquired by the base station identification processing method of the present invention and the data acquired by the phase difference detection method (upper principal component variance value, or phase difference variance value) are shown as black circles. Furthermore, it is assumed that the radio communication device 100 has not moved (its position has not changed) during the period from time t0 to t4, and no handover processing or the like has occurred.

[0087] As can be seen from Figure 9, the base station identification processing method of the present invention can identify base stations with high accuracy (because the upper principal component variance values ​​vary greatly when the base stations are different), so the upper principal component variance values ​​V of base stations BS1 to BS7 at times t0 to t3 (1) ~V (7) The data distributions are almost identical, and it can be clearly seen that at time t4, the data from base station BS6 disappears and the data from the fraudulent base station V' appears. In the wireless communication device 100, the appearance of a fraudulent base station can be detected by detecting the change in the data distribution of the upper principal component variance values ​​from time t3 to t4.

[0088] On the other hand, with the phase difference detection method, there is almost no difference in the variance of the phase difference of each base station, making it difficult to distinguish between base stations and difficult to detect the appearance of an unauthorized base station.

[0089] Summary As described above, in the communication system 1000, the wireless communication device 100 accurately reflects the hardware characteristics specific to the base station antenna, and the top N eigenvalues ​​derived from the CSI matrix are... bestThe base station is identified by the variance values ​​of the individual base stations. When the base stations are different, the upper principal component variance values ​​vary greatly, so in the communication system 1000, the wireless communication device 100 determines the upper N best Based on the variance values ​​of the individual base stations, base stations can be identified with high accuracy. Furthermore, by performing time-series analysis using the base station identification processing result data acquired by the wireless communication device 100, it is possible to detect fraudulent base stations operated by third parties with high accuracy. In addition, in the communication system 1000, the wireless communication device 100 analyzes the top N eigenvalues ​​derived from the CSI matrix. best Since it only requires obtaining the variance values ​​of a single unit, it does not require modification of the communication protocol. Furthermore, since the wireless communication device 100 only receives radio waves (wireless communication signals) from receivable base stations (mutual communication between the wireless communication device 100 and the base station is unnecessary), base station identification processing can be performed using a passive method.

[0090] Therefore, the communication system 1000 can identify base stations with high accuracy simply by receiving radio waves from them (using a passive method), without requiring any modification of the communication protocol. Furthermore, the communication system 1000 can detect unauthorized base stations operated by third parties with high accuracy by performing, for example, time-series analysis based on the base station identification processing result data acquired by the wireless communication device 100.

[0091] In the above, the column vector H in the wireless communication device 100 has estimated transfer function values ​​for each subcarrier at time step t as its elements. t (i) For this, we obtain the covariance matrix, obtain the eigenvalues, and the top N of the eigenvalues. best While we have explained the case of obtaining individual variance values, this is not the only way to do so.

[0092] For example, in the wireless communication device 100, a column vector H whose elements are estimated values ​​of the transfer function for each subcarrier at time step t. t (i) Each element is a transfer function H k,t (i) Instead, phase arg(H k,t(i) Let )(arg(z): argument of z) (data only of the phase frequency response characteristics), obtain the covariance matrix, obtain the eigenvalues, and the top N of the eigenvalues best Alternatively, we can obtain individual variance values. In this case, since each element of the covariance matrix will be a real number, there will be no need to perform complex calculations (only real number operations will be required), thus reducing the amount of computation.

[0093] Furthermore, in the wireless communication device 100, a column vector H whose elements are estimated values ​​of the transfer function for each subcarrier at time step t is used. t (i) Each element is a transfer function H k,t (i) Instead, amplitude amp(H k,t (i) Let )(amp(z): amplitude of z) (data consisting only of the frequency response characteristics of the amplitude), obtain the covariance matrix, obtain the eigenvalues, and the top N of the eigenvalues best Alternatively, we can obtain individual variance values. In this case, since each element of the covariance matrix will be a real number, there will be no need to perform complex calculations (only real number operations will be required), thus reducing the amount of computation.

[0094] ≪First Variation≫ Next, a first modified example of the first embodiment will be described. Note that parts similar to those in the above embodiment are denoted by the same reference numerals, and detailed descriptions are omitted.

[0095] Figure 10 is a schematic diagram of the communication system 1000A according to a first modified example of the first embodiment.

[0096] Figure 11 is a schematic diagram of the wireless communication device 100A according to a first modified example of the first embodiment.

[0097] The modified communication system 1000A has a configuration in which the wireless communication device 100 is replaced with a wireless communication device 100A (wireless communication device) in the communication system 1000 of the first embodiment.

[0098] As shown in Figure 11, the modified wireless communication device 100A has a configuration in which a communication interface unit 5 is added to the wireless communication device 100 of the first embodiment. Otherwise, it is the same as the first embodiment.

[0099] The communication interface unit 5 of the wireless communication device 100A is a communication interface for communicating with external devices by wire and / or wireless means. The communication interface unit 5 receives the data Dout output from the base station identification unit 3 and outputs the data including the data Dout to the outside as data D_rst.

[0100] The operation of the wireless communication device 100A of the communication system 1000A configured as described above will now be explained. Parts that are the same as those in the above embodiment will be omitted from the explanation.

[0101] The communication interface unit 5 receives the data Dout output from the base station identification unit 3, converts the data Dout into a data (signal) format that can be transmitted via the wired and / or wireless transmission path to which the communication interface unit 5 is connected, and sends it as data D_rst to the communication carrier (base station BS). i It is transmitted to a device (not shown) of a telecommunications carrier that can control it.

[0102] The telecommunications carrier's equipment receives the data D_rst from the wireless communication device 100A and analyzes the data D_rst to determine whether or not an unauthorized base station has appeared. If the telecommunications carrier's equipment determines that an unauthorized base station has appeared in the area where the wireless communication device 100A is located, it transmits radio waves (wireless communication signals) containing data indicating that "an unauthorized base station may have appeared" to mobile terminals, wireless communication devices, mobile phones, etc., located within the area where the wireless communication device 100 is located, for example, by paging.

[0103] Then, mobile terminals, wireless communication devices, cell phones, etc. located within the area where the wireless communication device 100 is present receive the radio waves (wireless communication signals) generated by the paging process and receive data (alerts) indicating that "there is a possibility that an unauthorized base station has appeared." As a result, mobile terminals, wireless communication devices, cell phones, etc. located within the area where the wireless communication device 100 is present can recognize the risk of an unauthorized base station appearing through the data (alerts) indicating that "there is a possibility that an unauthorized base station has appeared."

[0104] Furthermore, if the location of the wireless communication device 100A is registered in the home memory, similar to a mobile phone, the telecommunications carrier will know the location of the wireless communication device 100A and the base station BS that the wireless communication device 100A can receive. i The area where the radio waves can reach can be determined from the location of the wireless communication device 100A in the home memory. On the other hand, if the telecommunications carrier cannot determine the location of the wireless communication device 100A using the home memory, the wireless communication device 100A can transmit information about its own location to the telecommunications carrier's equipment via the communication interface unit 5.

[0105] Furthermore, the wireless communication device 100A is used at the base station BS. i If it is possible to transmit the data D_rst and / or the location information of the radio communication device 100A via wireless communication with base station BS, i The data D_rst and / or the location information of the radio communication device 100A may be transmitted via wireless communication. In this case, the telecommunications carrier transmits the data from the radio communication device 100A to the base station BS. i You can receive it via that.

[0106] As described above, in the modified communication system 1000A, data acquired by the wireless communication device 100A is transmitted to the telecommunications carrier's equipment, and the telecommunications carrier can notify mobile terminals, wireless communication devices, mobile phones, etc. in the area where the wireless communication device 100A is located of the appearance of an unauthorized base station by, for example, by paging. The process of detecting (determining) the appearance of an unauthorized base station using the base station identification processing result may be performed by the wireless communication device 100A or by the telecommunications carrier's equipment.

[0107] ≪Second variation≫ Next, a second modified example of the first embodiment will be described. Note that parts similar to those in the above embodiment are denoted by the same reference numerals, and detailed descriptions are omitted.

[0108] Figure 12 shows a user terminal UE according to a first modified example of the first embodiment. i This is a schematic diagram of the system.

[0109] In this modified communication system, the user terminal UE i However, it has a configuration in which the base station identification unit 3 of the wireless communication device 100 of the first embodiment is installed.

[0110] User Terminal UE i As shown in Figure 12, it comprises an antenna Ant_rx, an RF demodulation processing unit U1, a BB demodulation processing unit U2, a data processing unit U4, a base station identification unit U3, and a warning display unit U5.

[0111] The RF demodulation processing unit U1, BB demodulation processing unit U2, and data processing unit U4 have the same configuration and functions as the RF demodulation processing unit 1, BB demodulation processing unit 2, and data processing unit 4 of the wireless communication device 100, respectively. These functional units are general functional units for receiving wireless communication signals and are typically installed in ordinary (general) user terminal devices.

[0112] The base station identification unit U3 has the same configuration and function as the base station identification unit 3 of the wireless communication device 100 in the first embodiment. The base station identification unit U3 outputs data Dout to the warning display unit U5.

[0113] The warning display unit U5 displays the data Dout(base station identification processing result data (upper principal component variance value V)) output from the base station identification unit U3. (i) The data set Dset_V and / or the base station identification result data based on the data set Dset_V) are input, and a warning display (alert notification) is made based on the Dout. The warning display unit U5 performs time-series analysis using, for example, the base station identification processing result data acquired in time series, and the user terminal UE i The device determines whether or not there is a possibility of an unauthorized base station appearing within the communication range (area) of the device. The warning display unit U5 then displays a warning to the user terminal UE. i If (the device) determines that there is a possibility of an unauthorized base station appearing within the communication range (area), for example, the user terminal UE i An alert notification (warning display) is shown on the display unit (not shown). This causes the user terminal UE to display an alert notification (warning display). i The user is the user terminal UE. i The device can recognize that there is a possibility of an unauthorized base station appearing within its communication range (area).

[0114] As described above, the user terminal UE of this modified example i It includes a base station identification unit U3, and the base station identification unit U3 processes the base station identification processing result data (upper principal component variance value V (i) The data set Dset_V and / or the base station identification result data based on the data set Dset_V can be obtained, and the warning display unit U5 can detect an unauthorized base station and display a warning based on the base station identification processing result data. Therefore, the user terminal UE of this modified example can obtain the data set Dset_V and / or the base station identification result data based on the data set Dset_V, and the warning display unit U5 can detect an unauthorized base station and display a warning. i Therefore, the user's user terminal UE i The device can appropriately recognize if there is a possibility that an unauthorized base station has appeared within the communication range (area) of its own device.

[0115] [Other embodiments] In the above embodiments (including modified examples), any two or more embodiments (modified examples) may be combined to realize a communication system, a wireless communication device, or a mobile terminal.

[0116] Furthermore, in the above embodiments (including modifications), we have described a case in which, in a wireless communication device, the pilot symbol determined by the communication method adopted by the communication system is used as known data to determine the transfer function for each subcarrier and obtain the CSI matrix. However, we are not limited to this, and other known data may be used to determine the transfer function for each subcarrier and obtain the CSI matrix. Furthermore, although the above embodiments (including modified examples) describe a case in which the upper principal component variance acquisition processing unit 33 in a wireless communication device performs a process to acquire the variance of the upper principal components (upper principal component variance acquisition process), the invention is not limited to this. For example, in a wireless communication device, instead of the variance of the upper principal components, the standard deviation of the upper principal components or the sum of the absolute values ​​of the upper principal components may be used to perform a process to acquire the statistics of the upper principal components.

[0117] Furthermore, in the above embodiment (including modified examples), in the communication system, base station BS i The examples given, and the case where each wireless communication device has one antenna, are not limited to this, and the base station BS i The present invention may also be applied when each wireless communication device has multiple antennas. For example, base station BS i If the number of transmitting antennas is M' and the number of receiving antennas of the wireless communication device is N', the transfer function for each subcarrier between M' × N' antennas may be calculated, a CSI matrix may be obtained, and base station identification processing may be performed in the same manner as in the above embodiment (including modified versions).

[0118] Furthermore, although the above embodiments (including modified examples) describe the case where a base station is recognized, the present invention is not limited to this, and for example, it may be applied to a wireless LAN communication system. In this case, the base station of the above embodiments (including modified examples) can be used as an access point, and the same processing as in the above embodiments (including modified examples) can be performed.

[0119] Furthermore, in the communication system, wireless communication device, and user terminal described in the above embodiments (including modified examples), each block may be individually integrated into a single chip using semiconductor devices such as LSIs, or it may be integrated into a single chip including some or all of the blocks.

[0120] Although we have used the term LSI here, depending on the degree of integration, they may also be called IC, system LSI, super LSI, or ultra LSI.

[0121] Furthermore, the method of integrated circuit implementation is not limited to LSIs; it may also be implemented using dedicated circuits or general-purpose processors. After LSI manufacturing, FPGAs (Field Programmable Gate Arrays) that can be programmed, or reconfigurable processors that allow for the reconfiguration of the connections and settings of circuit cells inside the LSI, may also be used.

[0122] Furthermore, some or all of the processing of each functional block in each of the above embodiments (including modified versions) may be implemented by a program. And some or all of the processing of each functional block in each of the above embodiments is performed by a central processing unit (CPU) in a computer. The programs for each of these processes are stored in a storage device such as a hard disk or ROM, and are read from the ROM or RAM and executed.

[0123] Furthermore, each of the processes in the above embodiments (including modified versions) may be implemented by hardware, or by software (including cases where it is implemented together with an OS (operating system), middleware, or a predetermined library). Moreover, it may be implemented by a mixed process of software and hardware.

[0124] Furthermore, for example, when each functional part of the above embodiment (including modified versions) is implemented by software, the hardware configuration shown in Figure 13 (for example, a hardware configuration in which a CPU (which may be a GPU), ROM, RAM, input unit, output unit, etc. are connected by a bus) may be used to implement each functional part by software processing.

[0125] Furthermore, when each functional part of the above embodiment (including modified examples) is implemented by software, the software may be implemented using a single computer having the hardware configuration shown in Figure 13, or it may be implemented by distributed processing using multiple computers.

[0126] Furthermore, the execution order of the processing method in the above embodiments is not necessarily limited to the description of the embodiments, and the execution order can be changed without departing from the spirit of the invention. Also, in the processing method in the above embodiments, some steps may be executed in parallel with other steps without departing from the spirit of the invention.

[0127] A computer program that causes a computer to execute the method described above, and a computer-readable recording medium on which such program is recorded, are included in the scope of the present invention. Examples of computer-readable recording media include flexible disks, hard disks, CD-ROMs, MOs, DVDs, DVD-ROMs, DVD-RAMs, high-capacity DVDs, next-generation DVDs, and semiconductor memory.

[0128] The above-mentioned computer program is not limited to one recorded on the above-mentioned recording medium, but may also be transmitted via telecommunications lines, wireless or wired communication lines, networks such as the Internet, etc.

[0129] It should be noted that the specific configuration of the present invention is not limited to the embodiments described above, and various changes and modifications are possible without departing from the spirit of the invention.

[0130] [Note] The present invention can also be expressed as follows.

[0131] The first invention is a wireless communication device capable of receiving wireless communication signals from a base station that transmits a wireless communication signal obtained by performing data modulation on a symbol consisting of one or more bit sequences using multiple subcarriers, and performing RF modulation on the baseband modulated signal, comprising an RF demodulation processing unit, a BB demodulation processing unit, and a base station identification unit.

[0132] The RF demodulation processing unit obtains a baseband demodulated signal by performing RF demodulation processing on the wireless communication signal transmitted from the base station.

[0133] The BB demodulation processing unit performs baseband demodulation processing on the baseband demodulated signal to acquire the symbols corresponding to the transmitted symbols, which are data-modulated symbols at the base station, as demodulated symbols.

[0134] The base station identification unit obtains the frequency response characteristics for each subcarrier based on the transmission symbol and demodulation symbol, obtains a CSI matrix based on the obtained frequency response characteristics, and performs base station identification processing, which identifies the base station based on the statistical values ​​of the eigenvalues ​​derived from the obtained CSI matrix.

[0135] This wireless communication device identifies base stations based on eigenvalue statistics derived from a CSI matrix, which accurately reflect the unique hardware characteristics of the base station's antenna. Therefore, this wireless communication device can accurately identify base stations, and as a result, can detect, for example, unauthorized base stations operated by third parties with high accuracy. Furthermore, since this wireless communication device only obtains eigenvalue statistics derived from the CSI matrix, it does not require any modification of the communication protocol.

[0136] Therefore, this wireless communication device can detect unauthorized base stations operated by third parties with high accuracy without requiring any modification of the communication protocol.

[0137] The "statistics of eigenvalues" include, for example, the variance of an eigenvalue, the standard deviation of an eigenvalue, the variances of the top multiple eigenvalues, the standard deviations of the top multiple eigenvalues, and the sum of the absolute values ​​of the eigenvalues.

[0138] The second invention is the same as the first invention, and the statistical values ​​are derived from the CSI matrix, with N being the largest in absolute value of the eigenvalues. best pieces(N best Obtain the eigenvalues ​​of (a natural number), and obtain the obtained N best This is the variance of the individual eigenvalues.

[0139] Therefore, in this wireless system, the eigenvalues ​​are sorted from largest to smallest, N. best The variance of the individual eigenvalues ​​allows for highly accurate identification of base stations.

[0140] The third invention is the same as the first invention, wherein the base station identification unit uses the phase frequency response characteristics as the frequency response characteristics, obtains a CSI matrix based on the phase frequency response characteristics, and performs a process to identify a base station based on the statistical values ​​of the eigenvalues ​​derived from the obtained CSI matrix.

[0141] This allows the wireless communication device to identify a base station based on statistical values ​​of eigenvalues ​​derived from the phase frequency response characteristics.

[0142] The fourth invention is the first invention, wherein the base station identification unit performs base station identification processing for multiple base stations in a time series, analyzes the result data obtained by the base station identification processing, and outputs determination data indicating that there is a possibility that an unauthorized base station has appeared if the amount of change in the time series of the data distribution of the result data is greater than a predetermined value.

[0143] As a result, this wireless communication device can analyze the result data obtained through base station identification processing over time, and if there is a large change in the data distribution (for example, the amount of change can be identified by the sum of squared errors of the data distribution at two time points or by KL divergence), it can output judgment data indicating that there is a possibility that an unauthorized base station has appeared.

[0144] The fifth invention is the first invention, further comprising a warning display unit that determines whether or not there is a possibility that an unauthorized base station has appeared based on the result data of the base station identification process, and displays a warning if it is determined that there is a possibility that an unauthorized base station has appeared.

[0145] As a result, this wireless communication device can display a warning if its warning display unit determines that there is a possibility of an unauthorized base station appearing. The sixth invention is one of the first to fifth inventions, wherein the base station is a wireless LAN access point.

[0146] This allows the wireless communication device to identify wireless LAN access points with high accuracy, and as a result, it can, for example, detect the appearance of an unauthorized access point.

[0147] The seventh invention relates to one or more base stations, which are managed by a telecommunications carrier, This communication system comprises a wireless communication device, which is one of the first to fifth inventions, capable of receiving wireless communication signals from a base station, and a communication carrier communication device, which can be controlled by a communication carrier.

[0148] The wireless communication device can transmit the result data of the base station identification process to the telecommunications carrier's communication equipment.

[0149] The telecommunications carrier's communication equipment receives the result data of the base station identification process, analyzes the result data, and if it determines that there is a possibility that an unauthorized base station has appeared, it transmits an alert signal indicating the possible appearance of an unauthorized base station to the area where the wireless communication equipment is located, using one or more base stations that the wireless communication equipment can receive radio waves from.

[0150] This allows the communication system to use data acquired by wireless communication devices to send alert signals from the carrier's communication equipment to mobile terminals and wireless communication devices in the area where the wireless communication device is located, indicating that an unauthorized base station may have appeared.

[0151] The eighth invention is a wireless communication method capable of receiving wireless communication signals from a base station that transmits a wireless communication signal obtained by performing data modulation on a symbol consisting of one or more bit sequences using multiple subcarriers, and performing RF modulation on the baseband modulated signal, comprising an RF demodulation step, a BB demodulation step, and a base station identification step.

[0152] The RF demodulation processing step involves performing RF demodulation on the radio communication signal transmitted from the base station to obtain a baseband demodulated signal.

[0153] The BB demodulation processing step involves performing baseband demodulation on the baseband demodulated signal to obtain the symbols corresponding to the transmitted symbols, which are data-modulated symbols at the base station, as demodulated symbols.

[0154] The base station identification step involves obtaining frequency response characteristics for each subcarrier based on the transmitted and demodulated symbols, obtaining a CSI matrix based on the obtained frequency response characteristics, and performing a base station identification process based on the statistical values ​​of the eigenvalues ​​derived from the obtained CSI matrix.

[0155] This makes it possible to realize a wireless communication method that produces the same effects as the first invention.

[0156] The ninth invention is a program for causing a computer to execute the wireless communication method, which is the eighth invention.

[0157] This makes it possible to realize a program that causes a computer to execute a wireless communication method that has the same effect as the first invention. [Explanation of symbols]

[0158] 1000, 1000A communication system 100, 100A Wireless communication equipment (wireless communication device) 1. U1 RF Demodulation Processing Unit 2. U2 BB demodulation processing unit 3. U3 Base Station Identification Unit

Claims

1. A wireless communication device capable of receiving wireless communication signals from a base station that transmits a wireless communication signal obtained by performing data modulation on a symbol consisting of one or more bit sequences using multiple subcarriers, and by performing RF modulation on the baseband modulated signal, An RF demodulation processing unit that performs RF demodulation processing on the wireless communication signal transmitted from the base station to acquire a baseband demodulated signal, A BB demodulation processing unit performs baseband demodulation processing on the aforementioned baseband demodulated signal to acquire symbols corresponding to the transmitted symbols, which are data-modulated symbols at the base station, as demodulated symbols. A base station identification unit performs a base station identification process, which involves obtaining frequency response characteristics for each subcarrier based on the transmission symbol and the demodulation symbol, obtaining a CSI matrix based on the obtained frequency response characteristics, and identifying a base station based on statistical values ​​of eigenvalues ​​derived from the obtained CSI matrix. A wireless communication device equipped with the following features.

2. The aforementioned statistical values ​​are selected from the eigenvalues ​​derived from the CSI matrix, starting with the N eigenvalues ​​with the largest absolute values. ｂｅｓｔ pieces (N ｂｅｓｔ Obtain the eigenvalues ​​of the natural number (N) and obtain the obtained N ｂｅｓｔ The variance of the individual eigenvalues, The wireless communication device according to claim 1.

3. The base station identification unit is, The frequency response characteristics are defined as the phase frequency response characteristics, the CSI matrix is ​​obtained based on the phase frequency response characteristics, and the base station is identified based on the statistical values ​​of the eigenvalues ​​derived from the obtained CSI matrix. The wireless communication device according to claim 1.

4. The base station identification unit is, The system performs the base station identification process on multiple base stations in a time series, analyzes the result data obtained through the base station identification process, and outputs judgment data indicating that there is a possibility that an unauthorized base station has appeared if the amount of change in the data distribution of the result data over time is greater than a predetermined value. The wireless communication device according to claim 1.

5. The system further includes a warning display unit that determines whether or not there is a possibility of an unauthorized base station appearing based on the result data of the base station identification process, and displays a warning if it determines that there is a possibility of an unauthorized base station appearing. The wireless communication device according to claim 1.

6. The aforementioned base station is a wireless LAN access point. A wireless communication device according to any one of claims 1 to 5.

7. One or more base stations, the said base stations being managed by a telecommunications carrier, A wireless communication device according to any one of claims 1 to 5, capable of receiving wireless communication signals from the base station, A telecommunications carrier communication device controllable by the aforementioned telecommunications carrier, A communication system comprising, The wireless communication device is capable of transmitting the result data of the base station identification process to the telecommunications carrier communication device. The telecommunications carrier communication device receives the result data of the base station identification process, analyzes the result data, and if it determines that there is a possibility that an unauthorized base station has appeared, it transmits an alert signal indicating the possibility of an unauthorized base station appearing to the area where the wireless communication device is located, via one or more base stations from which the wireless communication device can receive radio waves. Communication system.

8. A wireless communication method capable of receiving wireless communication signals from a base station that transmits a wireless communication signal obtained by performing data modulation on a symbol consisting of one or more bit sequences using multiple subcarriers to acquire a baseband modulated signal, and then performing RF modulation on the baseband modulated signal, The RF demodulation processing step involves performing RF demodulation processing on the wireless communication signal transmitted from the base station to obtain a baseband demodulated signal. The BB demodulation processing step involves performing baseband demodulation processing on the baseband demodulated signal to obtain a symbol corresponding to the transmitted symbol, which is a symbol data-modulated at the base station, as a demodulated symbol. A base station identification step involves obtaining frequency response characteristics for each subcarrier based on the transmission symbol and the demodulation symbol, obtaining a CSI matrix based on the obtained frequency response characteristics, and performing a base station identification process based on statistical values ​​of eigenvalues ​​derived from the obtained CSI matrix to identify a base station. A wireless communication method that includes the following features.

9. A program for causing a computer to execute the wireless communication method described in claim 8.

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