CN108156102A - The blind authentication method and system of frequency selective fading channels based on smoothing technique - Google Patents

Abstract

The invention discloses a blind authentication method of a frequency selective fading channel based on smoothing technology, which includes transmitting a carrier signal to a frequency selective fading channel with multiple paths, the carrier signal includes an authentication signal, a pilot signal and an information signal, and the authentication The signal is superimposed on the pilot signal; the carrier signal is received, and the carrier signal in each path is sequentially processed by Blind Known Interference Cancellation (BKIC) to obtain the target signal, and the target signal is differentially processed to obtain the target authentication signal, BKIC processing Using adjacent symbols, eliminate the pilot signal through smoothing technology; obtain the reference signal based on the key and pilot signal, perform differential signal processing on the reference signal to obtain the reference authentication signal, and calculate the correlation between the target authentication signal and the reference authentication signal The test statistic is obtained; and the test statistic is compared with a prescribed threshold, so as to determine whether the carrier signal can pass the authentication.

Description

Blind authentication method and system for frequency selective fading channel based on smoothing technology

technical field

The invention relates to the technical field of wireless communication, in particular to a blind authentication method and system of a frequency selective fading channel based on smoothing technology.

Background technique

There are mainly three types of physical layer authentication technologies at present. The first authentication technology is spread spectrum technology (Auth-SS). The basic idea is to use traditional direct sequence spread spectrum or frequency modulation technology. Since different pulses use different frequencies, this This technique needs to sacrifice certain bandwidth for authentication. In addition, a key limitation of Auth-SS technology is that only users with prior knowledge about spread spectrum technology are allowed to participate in the communication. Therefore, the scope of application of this technique is relatively narrow.

The second type is based on time division multiplexing authentication technology (Auth-TDM), and the basic idea is that the transmitter periodically and alternately sends information signals and authentication signals. After receiving the signal, the receiving end directly extracts the expected authentication information to realize the authentication purpose of the signal. Auth-TDM is an authentication technology proposed in the early stage of wireless communication development. Its advantage is that it is easy to operate and does not need to preprocess authentication signals and information before transmitting signals (encryption may be performed for security reasons). The authentication signal is sent independently of the information signal, so it needs to occupy a certain bandwidth. With the continuous increase of the number of wireless information, the further improvement of the user's information privacy and the continuous enhancement of the enemy's attack technology, the security of this authentication technology Sex has been greatly challenged and has been unable to meet the needs of users.

The third authentication technology is the authentication superposition technology (Auth-SUP). The basic idea is to superimpose the authentication signal on the information signal (the method of superposition can be arbitrary, determined by the key), and then the transmitting end transmits it at the same time, and the receiving end receives it. After receiving the signal, use the key to extract the authentication signal in the superimposed signal to achieve the purpose of signal authentication.

Compared with the early Auth-TDM technology, the Auth-SUP authentication technology needs to process the authentication signal and the information signal before the signal is transmitted, which puts forward certain requirements on the signal processing capability of the transmitter, and is more complicated to implement than the Auth-TDM technology , the authentication signal and the information signal are sent at the same time, so no additional bandwidth will be occupied. At this time, because the authentication signal is superimposed on the information signal, the receiving end needs to extract the information after receiving the signal. The difficulty of signal processing is higher than that of Auth-TDM technology, but the concealment of authentication information is higher than that of Auth-TDM. In addition, since the authentication signal is equivalent to playing the role of noise for the extraction of the information signal, the SNR of the receiving end is correspondingly reduced, which has an adverse effect on the extraction of the information signal.

The existing Auth-TDM and Auth-SUP authentication technologies transmit another pilot signal in addition to information signals and authentication signals. This is because both authentication techniques require the receiving end to estimate the channel parameters and recover the symbols after receiving the signal, and then extract the authentication signal. At this time, certain requirements are placed on the signal processing capability of the receiving end. , in some specific occasions, these signal processing techniques may not be feasible, and it is easy to cause estimation errors in the process of channel parameter estimation and symbol recovery, which will have a negative impact on the extraction of the final authentication signal.

In addition, Auth-TDM, Auth-SS, and Auth-SUP all expose the fact that authentication information is included. Compared with conventional signals that do not include authentication information, Auth-SS and Auth-TDM technologies are more likely to cause The attention of other users, especially the hostile users, the hostile users analyze the signal, counterfeit or tamper, and the legitimate receiving end will not be able to authenticate the expected signal. Relatively speaking, the concealment of Auth-SUP authentication technology is obviously higher than Auth-SS and Auth-TDM. However, this superiority is based on the premise that the computing power of the hostile user is limited. Once the computing power of the hostile user increases, it is very likely to extract or even destroy the authentication information.

It has to be mentioned that the performance of the existing Auth-SS technology and Auth-SUP technology degrades severely in frequency selective fading channel scenarios. But the reality is that with the increasing number of wireless communication users, the communication environment will become more complex, and the possibility of being interfered will increase. With the increase in the number of urban communication users and the continuous development of cities, simple time Constant fading channels or simply time-varying fading channels are not enough to characterize the current communication environment. Especially because of the blocking of urban buildings, multipath fading has become the norm. Therefore, the physical layer authentication technology of wireless communication based on frequency selective fading channel has to be considered to improve the security of wireless communication and meet the communication security requirements of users.

Contents of the invention

The present invention is proposed in view of the above situation, and its purpose is to provide an authentication signal that does not need to occupy additional signal bandwidth, and the authentication signal does not become noise that affects the extraction of information signals in the carrier signal, and does not affect the statistical characteristics of the noise at the receiving end. Blind authentication method and system for frequency selective fading channel based on smoothing technique.

For this reason, the first aspect of the present invention provides a kind of blind authentication method of frequency selective fading channel based on smoothing technology, is the physical layer authentication method of the wireless communication system of wireless communication system with transmitter and receiver, it is characterized in that, It includes: the transmitting end transmits a carrier signal to a wireless channel, the carrier signal includes an authentication signal, a pilot signal and an information signal, the authentication signal is superimposed on the pilot signal, and the wireless channel has multiple paths A frequency selective fading channel; the receiving end receives the carrier signal, and sequentially performs blind known interference cancellation (Blind Known Interference Cancellation, BKIC for short) on the carrier signal in each path of the frequency selective fading channel ) processing to obtain a target signal, and performing differential signal processing on the target signal to obtain a target authentication signal, in the BKIC process, using adjacent symbols to eliminate the pilot signal through a smoothing technique; at the receiving end In, obtaining a reference authentication signal based on the key and the pilot signal, and calculating the correlation between the target authentication signal and the reference authentication signal to obtain a test statistic; and judging whether the test statistic is not less than a prescribed threshold , so as to determine whether the bearer signal can pass the authentication.

In the present invention, the authentication signal is superimposed on the pilot signal. Therefore, the SINR at the receiving end may not be affected. The BKIC process utilizes adjacent symbols to remove the pilot signal through smoothing techniques. In this case, the pilot signal can be eliminated without estimating the channel.

In the blind authentication method according to the first aspect of the present invention, the carrier signal is transmitted in blocks in the form of data blocks. Thus, it is convenient to operate on the data.

In the blind authentication method according to the first aspect of the present invention, in each block of the carrier signal, the sum of the signal length of the pilot signal and the signal length of the information signal is equal to the signal length of the carrier signal.

In addition, in the blind authentication method according to the first aspect of the present invention, the reference signal is obtained based on the key and the pilot signal by using a hash matrix. Thus, the reference signal is processed to obtain the reference authentication signal, and it can be determined whether the target authentication signal passes the authentication according to the correlation between the reference authentication signal and the target authentication signal.

In the blind authentication method according to the first aspect of the present invention, if the test statistic is not less than the prescribed threshold, the bearer signal passes the authentication.

In the blind authentication method according to the first aspect of the present invention, the prescribed threshold is obtained based on the statistical characteristics of the pilot signal and a preset upper limit of false alarm probability.

The second aspect of the present invention provides a blind authentication device for frequency selective fading channels based on smoothing technology, which includes a processor that executes the computer program stored in the memory to realize the physical layer blind authentication described in any one of the above an authentication method; and a memory.

A third aspect of the present invention provides a computer readable storage medium. The computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by a processor, the blind authentication method described in any one of the above-mentioned first aspects is implemented.

The fourth aspect of the present invention provides a blind authentication system for a frequency selective fading channel based on smoothing technology, which includes a transmitting device that transmits a carrier signal to a wireless channel, and the carrier signal includes an authentication signal, a pilot signal and information signal, the authentication signal is superimposed on the pilot signal, and the wireless channel is a frequency selective fading channel with multiple paths; the receiving device includes a first processing module, a second processing module and a determination module, the first The processing module receives the carrier signal, sequentially performs blind known interference cancellation (BKIC) processing on the carrier signal in each path of the frequency selective fading channel to obtain a target signal, and performs differential signal processing on the target signal Processing to obtain a target authentication signal, in the BKIC processing, using adjacent symbols to eliminate the pilot signal through a smoothing technique; a second processing module, which obtains a reference signal based on the key and the pilot signal, Perform differential signal processing on the reference signal to obtain a reference authentication signal, and calculate the correlation between the target authentication signal and the reference authentication signal processed by the differential signal to obtain a test statistic; and a decision module, which compares the The test statistic is compared to a specified threshold to determine whether the bearer signal can be authenticated.

In the present invention, the transmitting device of the blind authentication system superimposes the authentication signal on the pilot signal. In this way, additional transmission bandwidth resources can not be occupied. The receiving device BKIC of the blind authentication system uses adjacent symbols to eliminate the pilot signal through smoothing technology. In this case, the receiving device can cancel the pilot signal without estimating the channel.

In the blind authentication system according to the fourth aspect of the present invention, the second processing module obtains the reference signal based on the key and the pilot signal by using a hash matrix. Thus, the reference signal is processed to obtain the reference authentication signal, and it can be determined whether the target authentication signal passes the authentication according to the correlation between the reference authentication signal and the target authentication signal.

In the blind authentication system according to the fourth aspect of the present invention, the predetermined threshold in the determination module is obtained based on the statistical characteristics of the pilot signal and a preset upper limit of false alarm probability.

Compared with the prior art, the embodiment of the present invention has the following beneficial effects:

Compared with the existing Auth-SS, Auth-SUP, and Auth-TDM, the authentication of the physical layer of the wireless communication does not need to occupy additional signal bandwidth, and the authentication signal does not become noise that affects the extraction of received signals, and does not affect the reception Statistical properties of end noise. The blind authentication technology proposed by the present invention deals with frequency-selective fading channels, and is more suitable for complex and changeable wireless communication environments in actual communication scenarios. In addition, since in the present invention, the authentication signal is superimposed on the pilot signal, if the whole of the superimposed signal of the authentication signal and the pilot is used as a pilot signal for channel estimation, the accuracy of channel estimation can also be improved .

Description of drawings

FIG. 1 is a schematic diagram showing signal transmission of a physical layer blind authentication method according to an embodiment of the present invention.

Fig. 2 is a schematic flow chart showing a physical layer blind authentication method involved in an embodiment of the present invention.

Fig. 3 is a schematic diagram showing the structure of signals transmitted by the transmitting end of the physical layer blind authentication method involved in the embodiment of the present invention.

Fig. 4 is a schematic diagram showing a blind known interference cancellation (BKIC) processing flow at the receiving end of the physical layer blind authentication method according to the embodiment of the present invention.

Fig. 5 is a schematic diagram showing a signal processing module of a transmitting end of the physical layer blind authentication system involved in an embodiment of the present invention.

FIG. 6 is a schematic diagram showing a signal processing module at a receiving end of a physical layer blind authentication system according to an embodiment of the present invention.

Fig. 7 is a schematic structural diagram showing a physical layer blind authentication device involved in an embodiment of the present invention.

Detailed ways

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are given to the same components, and repeated descriptions are omitted. In addition, the drawings are only schematic diagrams, and the ratio of dimensions between components, the shape of components, and the like may be different from the actual ones.

It should be noted that the terms "first", "second", "third" and "fourth" in the description and claims of the present invention and the above drawings are used to distinguish different objects, rather than using to describe a specific order. Furthermore, the terms "include" and "have", as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally also includes unlisted steps or units, or optionally further includes For other steps or units inherent in these processes, methods, products or apparatuses.

This embodiment discloses a blind authentication method, device and system of a frequency selective fading channel based on smoothing technology, and is a physical layer authentication method, device and system of a wireless communication system with a transmitting end and a receiving end. That is, this embodiment discloses a physical layer blind authentication method, device and system for wireless communication frequency selective fading channels based on smoothing technology. It enables more accurate physical layer authentication. A detailed description is given below in conjunction with the accompanying drawings.

FIG. 1 is a schematic diagram showing signal transmission of a physical layer blind authentication method according to an embodiment of the present invention.

In this embodiment, as shown in FIG. 1 , the physical layer blind authentication method for wireless communication frequency selective fading channels based on smoothing technology is based on a general signal transmission model. In this signal transmission model, a total of 4 users are included, among which the sender (transmitter) is the legal sender, the transmitter sends signals to the legal receiver, that is, the receiver, and the other two receivers are the monitoring user and the receiver in the system respectively. hostile user. Once hostile users find that there may be authentication information in the signal sent by the transmitter, they will analyze the signal and try to extract, destroy, or even tamper with the authentication information. However, this embodiment is not limited thereto. There may be two or more transmitters, two or more legal receivers, and two or more listening users and hostile users.

In this embodiment, it is assumed that the transmitting end and the receiving end share a key for authentication, so that the receiving end can use the key to extract authentication information from the signal transmitted by the transmitting end. The authentication signal contains authentication information. In this embodiment, the bearer signal includes the authentication signal, and the normal signal does not include the authentication signal. The monitoring user knows nothing about the authentication method. Although the signal sent by the transmitter can be accepted and restored, it will not conduct in-depth analysis of the signal and will not affect the authentication process. The hostile user can perceive the existence of the authentication signal by analyzing the characteristics of the signal, and intends to destroy the authentication signal.

In this embodiment, the transmitting end in the above signal model may include a base station or a user equipment. A base station (eg, an access point) may refer to a device in an access network that communicates with wireless terminals through one or more sectors over an air interface. The base station can be used to convert received over-the-air frames to and from IP packets, acting as a router between the wireless terminal and the rest of the access network, which can include an Internet Protocol (IP) network. The base station may also coordinate attribute management for the air interface. For example, the base station may be a base station (BTS, Base Transceiver Station) in GSM or CDMA, or a base station (NodeB) in WCDMA, or an evolved base station (NodeB or eNB or e-NodeB, evolutional NodeB) in LTE. B), this embodiment is not limited.

User equipment may include but not limited to smartphones, notebook computers, personal computers (PersonalComputer, PC), personal digital assistants (Personal Digital Assistant, PDA), mobile Internet devices (Mobile Internet Device, MID), wearable devices (such as smart watches, Smart bracelets, smart glasses) and other electronic devices, wherein the operating system of the user device may include but not limited to Android operating system, IOS operating system, Symbian (Symbian) operating system, Black Berry (Blackberry) operating system, The Windows Phone8 operating system and the like are not limited in this embodiment.

In this embodiment, in the above signal model, the transmitting end sends a signal to the receiving end through a wireless channel, where the receiving end may include a base station. A base station (eg, an access point) may refer to a device in an access network that communicates with wireless terminals through one or more sectors over an air interface. The base station can be used to convert received over-the-air frames to and from IP packets, acting as a router between the wireless terminal and the rest of the access network, which can include an Internet Protocol (IP) network. The base station may also coordinate attribute management for the air interface. For example, the base station may be a base station (BTS, Base Transceiver Station) in GSM or CDMA, or a base station (NodeB) in WCDMA, or an evolved base station (NodeB or eNB or e-NodeB, evolutional NodeB) in LTE. B), this embodiment is not limited.

The receiving end can also include user equipment, which can include but not limited to smartphones, notebook computers, personal computers (Personal Computer, PC), personal digital assistants (Personal Digital Assistant, PDA), mobile Internet devices (Mobile Internet Device, MID ), wearable devices (such as smart watches, smart bracelets, smart glasses) and other electronic devices, where the operating system of the user device may include but not limited to Android operating system, IOS operating system, Symbian (Symbian) operating system , Black Berry (Blackberry) operating system, Windows Phone8 operating system, etc., this embodiment is not limited.

This embodiment discloses a physical layer blind authentication method of a wireless communication frequency selective fading channel based on a smoothing technology. Fig. 2 is a schematic flow chart showing a physical layer blind authentication method involved in an embodiment of the present invention. Fig. 3 is a schematic diagram showing the structure of signals transmitted by the transmitting end of the physical layer blind authentication method involved in the embodiment of the present invention.

In this embodiment, the physical layer blind authentication method of wireless communication frequency selective fading channel based on smoothing technology is a physical layer authentication method of wireless communication system with a transmitting end and a receiving end. Based on the above signal transmission model, as shown in FIG. 2 , the transmitting end transmits the carrier signal to the wireless channel. Bearer signals include authentication signals, pilot signals and information signals. The authentication signal is superimposed on the pilot signal. The wireless channel is a frequency selective fading channel with multiple paths (step S101).

In step S101 , as shown in FIG. 3 , the carrier signal includes an authentication signal, a pilot signal and an information signal, and the authentication signal is superimposed on the pilot signal. The signal length of the authentication signal is equal to the signal length of the pilot signal. Therefore, superimposing the authentication signal on the pilot signal can avoid occupying additional signal bandwidth.

In this embodiment, the information signal includes the information to be delivered by the user at the transmitting end. The carrier signal sent by the transmitter is transmitted in blocks in the form of data blocks. Each block of carrier signals includes a pilot part and an information part. The pilot part includes authentication signals and pilot signals, and the information part includes information signals. In addition, the carrier signal is transmitted in blocks in the form of data blocks, which facilitates operations on the data.

In this embodiment, the signal length of the authentication signal or the pilot signal is the first length, the signal length of the information signal is the second length, and the length of each carrier signal is the total length. The sum of the signal length of the authentication signal or the pilot signal and the signal length of the information signal is equal to the length of each carrier signal. That is, the sum of the first length and the second length is equal to the total length.

In this embodiment, the authentication signal is obtained through a pilot signal and a key. That is, the pilot signal and the key use the hash matrix to obtain the authentication signal. The obtained authentication signal is superimposed on the pilot signal, and the pilot part of each carrier signal is obtained. The signal expression of the pilot part is as follows:

m _i =ρ _s p _i +ρ _t t _i (1)

In the signal expression (1) of the above-mentioned pilot part, and Power allocation factors for pilot information and authentication signals. Assuming that the authentication signal and the pilot signal are independent of each other, then we have

In this embodiment, the signal of the pilot part and the information signal of the information part are combined to form each carrier signal.

In addition, in this embodiment, the transmission channel of the bearer signal is a wireless channel, and is a frequency selective fading channel. A frequency selective fading channel has multiple paths, ie a frequency selective fading channel is a multipath channel. The carrier signal expression after frequency selective fading channel is as follows:

y _iL+k = h _iL+k x _iL+k +n _iL+k (2)

In this embodiment, the channel response h _iL+k of the frequency selective fading channel obeys the zero mean variance as The complex Gaussian distribution of , is the noise at the receiving end, and obeys the zero mean variance as Gaussian random variable of .

In this embodiment, in the channel response, is dynamic noise, and In general, the fading correlation coefficient a of a frequency selective fading channel is determined by the channel Doppler spread and the transmission bandwidth. In particular, a small value of a indicates fast fading, and a large value of a indicates slow fading. In many types of scenarios, the value of a is available at the receiving end. In the actual wireless system scenario, the value range of a is in a very small interval, such as a ∈ [0.9, 1].

In this embodiment, the physical layer blind authentication method further includes receiving the carrier signal at the receiving end, and sequentially performing blind known interference cancellation (BKIC) processing on the carrier signal in each path of the frequency selective fading channel to obtain the target signal. In BKIC processing, adjacent symbols are used to remove pilot signals by smoothing technology (step S102).

In this embodiment, the receiving end receives the bearer signal. The carrier signal contains a pilot part and an information part. The physical layer blind authentication method involved in this embodiment mainly processes the pilot part of the carrier signal at the receiving end. The expression of the pilot part of the carrier signal received by the receiving end is as follows:

In this embodiment, the radio channel is a frequency selective fading channel. A frequency selective fading channel has multiple paths. Wherein, D _max is the maximum delay information in multipath, and D _max is usually known in broadband wireless communication systems. For example, in an Orthogonal Frequency Division Multiplexing (OFDM) system, a predefined cyclic prefix determines the maximum delay among all paths.

In this embodiment, the following processing on the carrier signal refers to processing on the pilot part of the carrier signal.

In this embodiment, a blind authentication technique is used on each potential path of the frequency selective fading channel. Specifically, first, the carrier signal in the first path of the frequency-selective fading channel can be subjected to blind known interference cancellation (BKIC) processing, and then, similarly, the same blind known interference cancellation (BKIC) processing method can be used Remove the pilot signal in the carrier signal in the second path of the frequency-selective fading channel, repeat the above-mentioned blind known interference cancellation (BKIC) process _Dmax +1 times, so that in each path of the frequency-selective fading channel The pilot signals in the carrier signal are sequentially eliminated. That is, blind known interference cancellation (BKIC) processing is performed sequentially on the carrier signal in each path of the frequency selective fading channel.

In step S102, the receiving end receives the carrier signal, and sequentially performs blind known interference cancellation (BKIC) processing on the carrier signal in each path of the frequency selective fading channel to obtain the target signal. Among them, the blind known interference cancellation (BKIC) process uses adjacent symbols to eliminate the pilot signal in the carrier signal through smoothing technology. Generally, channel conditions need to be estimated to eliminate the pilot signal in the carrier signal. If the channel response cannot be effectively estimated, it is difficult to eliminate the pilot signal in the carrier signal. The blind known interference cancellation method can eliminate the pilot signal without estimating the channel.

In this implementation manner, the bearer signal received by the receiving end may or may not contain the authentication signal. It is assumed that the bearer signal contains authentication information as the first condition, and the bearer signal does not contain the authentication signal as the second condition.

Fig. 4 is a schematic diagram showing a blind known interference cancellation (BKIC) processing flow at the receiving end of the physical layer blind authentication method according to the embodiment of the present invention.

In this embodiment, as shown in FIG. 4 , the method of eliminating the pilot signal in the carrier signal is the same on each path of the frequency selective fading channel. Specifically, the carrier signal on each path of the frequency selective fading channel is processed by BKIC to eliminate the pilot signal. The BKIC processing method includes determining the expression of each symbol under different conditions (step S401) and using the expression of the symbol to estimate the target signal (step S402).

In step S401, the expression of each symbol under different conditions is determined.

Among them, under the first condition, the expression of each symbol is as follows:

k ∈ {1, 2, ..., L ₁ -1}

Under the second condition, the expression of each symbol is as follows:

It can be seen from the above formula that there is correlation noise between adjacent symbols, and the correlation noise in expression (4) cannot be corrected by ordinary noise whitening technology, it is necessary to eliminate the correlation noise through step S402, and estimate h _k ρ _t t _k +n _k .

In step S402, the expression of the symbol is used to estimate the target signal, and the above expression (4) is expressed as follows:

The estimated results can be obtained as follows:

Among them, ε _k in expression (9) is due to the residual signal generated by the BKIC module during the interference cancellation process, ε _k can be modeled as a Gaussian distribution, for slow fading, (a→1), the variance of ε _k is very small, so the ε _k in y _k can be removed to obtain the estimated h _k ρ _t t _k + _nk . Add the estimated h _k ρ _t t _k + _nk in each path to obtain the estimated target signal without pilot signal.

In addition, in step S102, the carrier signal is processed by BKIC to obtain a target signal, and the target signal is subjected to differential signal processing to obtain a target authentication signal.

In this embodiment, the differential signal processing method is as follows:

Under the first condition, the expression for differential signal processing is as follows:

where _Δk is the residual signal, which can be approximately modeled as 0 with mean variance as Gaussian random variable of .

Under the second condition, the expression for differential signal processing is as follows:

in is a complex Gaussian random variable with zero mean.

In this embodiment, the physical layer blind authentication method further includes, at the receiving end, obtaining a reference signal based on the key and the pilot signal, performing differential signal processing on the reference signal to obtain a reference authentication signal, and calculating the target authentication signal and the reference authentication signal. The correlation of the signals is used to obtain the test statistics (step S103).

In step S103, obtaining the reference signal based on the key and the pilot signal means using a hash matrix to obtain the reference signal from the key and the pilot signal. Thus, the reference signal is processed to obtain the reference authentication signal, and it can be determined whether the target authentication signal passes the authentication according to the correlation between the reference authentication signal and the target authentication signal.

In step S103, differential signal processing is performed on the reference signal to obtain a reference authentication signal, and the correlation between the target authentication signal and the reference authentication signal is calculated to obtain a test statistic, and the next step can be judged according to the value of the test statistic.

In this embodiment, differential signal processing is performed on the reference signal to obtain the reference authentication signal. The differential signal processing method is the same as the differential processing method in step S102 above.

In the above step S102, the bearer signal received by the receiving end may contain an authentication signal, the first condition is set that the bearer signal contains authentication information, and the second condition is set that the bearer signal does not contain the authentication signal.

Among them, at the receiving end, the carrier signal sequentially performs Blind Known Interference Cancellation (BKIC) processing on the carrier signal in each path of the frequency selective fading channel to obtain the target signal, and performs differential signal processing on the target signal to obtain the target authentication signal . At the receiving end, the reference signal is obtained based on the key and the pilot signal, and the reference signal is processed by differential (DP) signal to obtain the reference authentication signal. The rule for generating the reference signal by the hash matrix, key and pilot signal at the receiving end is the same as the rule for generating the authentication signal by the hash matrix, key and pilot signal at the sending end. The reference authentication signal can be regarded as the authentication signal in the first condition, and the target authentication signal can be regarded as the carrier signal in the first condition. Thus, the first condition may be expressed as the target authentication signal includes the reference authentication signal; the second condition may be expressed as the target authentication signal does not include the reference authentication signal.

In this embodiment, the physical layer blind authentication method further includes comparing the test statistic with a prescribed threshold, so as to determine whether the bearer signal can pass the authentication (step S104).

In step S104, if the test statistic is not less than the specified threshold, it is determined that the bearer signal has passed the authentication; if the test statistic is less than the specified threshold, it is determined that the bearer signal has not passed the authentication.

In this embodiment, if the test statistic is not less than the specified threshold, the carrier signal contains the reference authentication signal, that is, the carrier signal has passed the authentication; if the test statistic is smaller than the specified threshold, the carrier signal does not contain the reference authentication signal, that is, the carrier Signal is not authenticated.

In addition, in this embodiment, the predetermined threshold value is obtained through hypothesis verification conditions, and the above-mentioned first condition and second condition are respectively the first condition H ₁ and the second condition H ₀ of the hypothesis verification conditions.

In this embodiment, under the first condition _H1 , the expression of the test statistic is as follows:

Under the second condition H ₀ , the expression of the test statistic is as follows:

in, is 0 mean variance is Gaussian random variable, φ _i is 0 mean variance is Gaussian random variable of .

In addition, the specified threshold It is determined by the false alarm probability ε _FA related to the (τ _i |H ₀ ) distribution, expressed as follows:

Where (τ _i |H ₀ ) is the test statistic obtained under the second condition, that is, the statistical characteristic of the pilot signal. Therefore, the specified threshold can be obtained based on the statistical characteristics of the pilot signal and the preset upper limit of the false alarm probability.

In addition, in this embodiment, if the identity of the transmitter is authenticated, the authentication signal can be used as an additional pilot signal to recover the signal. Thus, the performance of signal symbol recovery and the performance of estimation of channel response can be improved.

In addition, in this embodiment, the authentication signal is superimposed on the pilot signal, which avoids adverse effects on the extraction of conventional signals. Thus, the reduction of the signal-to-interference-noise ratio (SINR) at the receiving end is avoided.

In this embodiment, the physical layer blind authentication method of the wireless communication frequency selective fading channel based on the smoothing technology does not need to occupy additional signal bandwidth. In addition, at the receiving end, when the information signal is extracted from the carrier signal, the authentication signal will not become noise of the information signal, that is, the authentication signal will not affect the extraction of the information signal. The authentication signal does not affect the statistical properties of the noise at the receiver.

In this embodiment, the physical layer blind authentication method deals with a frequency-selective fading channel with multiple paths, that is, a multi-path channel, which is more suitable for complex and changeable wireless communication environments in actual communication scenarios. In addition, the authentication signal is superimposed on the pilot signal. If the whole of the superimposed signal of the authentication signal and the pilot is used as a pilot signal for channel estimation, the accuracy of channel estimation can also be improved.

The embodiment discloses a physical layer blind authentication system of a wireless communication frequency selective fading channel based on a smoothing technology. Fig. 5 is a schematic diagram showing a signal processing module of a transmitting end of the physical layer blind authentication system involved in an embodiment of the present invention. FIG. 6 is a schematic diagram showing a signal processing module at a receiving end of a physical layer blind authentication system according to an embodiment of the present invention.

In this embodiment, as shown in FIG. 5 , the physical layer blind authentication system includes a transmitting device 20 . The transmitting device 20 includes a first generating module 201 , a second generating module 202 and a combining module 203 .

In this embodiment, as shown in FIG. 5 , the first generating module 201 generates an authentication signal. That is, the key and the pilot signal generate an authentication signal through the first generation module 201 . The first generation module 201 includes a hash matrix. The authentication signal is obtained by using the hash matrix of the key and the pilot signal. Wherein, the signal length of the obtained authentication signal is the same as that of the pilot signal.

In this embodiment, as shown in FIG. 5 , the second generation module 202 generates the pilot part of the carrier signal. That is, the authentication signal is loaded onto the pilot signal by the second generation module 202 to generate the pilot part of the carrier signal. The expression of the pilot part of the bearer signal is formula (1). In addition, the length of the pilot part of the bearer signal is the signal length of the authentication signal or the signal length of the pilot signal.

In this embodiment, as shown in FIG. 5 , the synthesis module 203 generates a carrier signal. That is to say, the pilot part and the information part of the carrier signal are combined through the combination module 203 to generate the carrier signal. The information part of the carrier signal is the information signal.

In this embodiment, the bearer signal is sent in blocks according to data blocks. Each block of carrier signals includes a pilot part and an information part. The sum of the signal length of the authentication signal or the pilot signal and the signal length of the information signal is equal to the length of each carrier signal. In addition, the carrier signal is transmitted in blocks in the form of data blocks, which facilitates operations on the data.

In this embodiment, the carrier signal generated by the transmitting device 20 at the transmitting end reaches the receiving device 30 at the receiving end through a wireless channel. In addition, the wireless channel is a frequency selective fading channel with multiple paths.

In this embodiment, the physical layer blind authentication system further includes a receiving device 30 . The receiving device 30 includes a first processing module, a second processing module and a determination module.

In this embodiment, the first processing module includes a Blind Known Interference Cancellation (BKIC) module 301 . The bearer signal goes through a blind known interference cancellation (BKIC) module 301 . Specifically, the carrier signal in each path of the frequency selective fading channel is sequentially processed by the blind known interference cancellation (BKIC) module 301 to eliminate the pilot frequency in the carrier frequency signal Signal.

In this embodiment, the Blind Known Interference Cancellation (BKIC) module 301 uses the BKIC processing method in step S102, which utilizes adjacent symbols and eliminates pilot signals through smoothing techniques. The specific steps are shown in Figure 4. BKIC processing includes determining the expression of each symbol under different conditions (step S401) and estimating the target signal by using the expression of the symbol (step S402).

In this embodiment, as shown in FIG. 6 , the first processing module further includes a differential (DP) processing module 302 . The DP processing module 302 uses the differential signal processing method in step S102. The DP processing module 302 performs differential signal processing on the target signal to obtain a target authentication signal. Thus, the influence of h _k in the target authentication signal is eliminated, that is, the influence of the channel on the bearer signal is eliminated.

In the DP processing module 302, under the first condition, the expression of differential signal processing is formula (10), where Δ _k is the residual signal, which can be modeled approximately as 0 with a mean variance of Gaussian random variable of . Under the second condition, the expression for differential signal processing is formula (11), where is a complex Gaussian random variable with zero mean.

In this embodiment, as shown in FIG. 6 , the second processing module further includes a hash matrix processing module 303 . The reference signal is obtained from the pilot signal and the key through the hash matrix processing module 303 . The hash matrix processing module 303 uses the method for generating reference signals in step S103. The hash matrix processing module 303 includes a hash matrix.

In this embodiment, as shown in FIG. 6 , the second processing module further includes a differential (DP) processing module 304 . The differential (DP) processing module 304 performs differential signal processing on the reference signal to obtain a reference authentication signal. The DP processing module 304 uses the differential signal processing method in step S103.

In this embodiment, as shown in FIG. 6 , the second processing module further includes an operation module 305 . The calculation module 305 is used to calculate the test statistics of the target authentication signal and the reference authentication signal. The calculation method used by the calculation module 305 is the calculation method in step S103.

In this embodiment, as shown in FIG. 6 , the second processing module further includes a determination module 306 . The decision module 306 determines whether the target authentication signal passes the authentication by comparing the test statistic with a prescribed threshold. That is, it is determined whether the bearer signal can pass the authentication.

In this embodiment, the predetermined threshold in the determination module 306 is obtained based on the statistical characteristics of the pilot signal and the preset upper limit of the false alarm probability. The calculation method of the predetermined threshold is the threshold calculation method in step S103.

This embodiment discloses a physical layer blind authentication device 50 for a wireless communication frequency selective fading channel based on a smoothing technology. Fig. 7 is a schematic structural diagram showing a physical layer blind authentication device involved in an embodiment of the present invention. In this embodiment, both the transmitting end and the receiving end include an authentication device 50 as shown in FIG. 7 .

In this embodiment, as shown in FIG. 7 , the authentication device 50 includes a processor 501 and a memory 502 . Wherein, the processor 501 and the memory 502 are respectively connected to the communication bus. The memory 502 may be a high-speed RAM memory, or a non-volatile memory (non-volatile memory). Those skilled in the art can understand that the structure of the authentication device 50 shown in FIG. 7 does not constitute a limitation to the present invention. It can be a bus structure or a star structure, and it can also include a structure other than that shown in FIG. More or fewer components, or combinations of certain components, or different arrangements of components.

Wherein, the processor 501 is the control center of the authentication device, which may be a central processing unit (Central Processing Unit, CPU). The software programs and/or modules, as well as call the program codes stored in the memory 502, are used to perform the following operations:

The transmitting end transmits a carrier signal to the wireless channel. The carrier signal includes an authentication signal, a pilot signal and an information signal. The authentication signal is superimposed on the pilot signal. The wireless channel is a frequency selective fading channel with multiple paths (by the authentication device 50 at the transmitting end) implement).

The receiving end receives the carrier signal, sequentially performs Blind Known Interference Cancellation (BKIC) processing on the carrier signal in each path of the frequency selective fading channel to obtain the target signal, and performs differential signal processing on the target signal to obtain the target authentication signal. In BKIC processing, the adjacent symbols are used to eliminate the pilot signal through smoothing technology; at the receiving end, the reference signal is obtained based on the key and the pilot signal, and the reference signal is differentially processed to obtain the reference authentication signal, and the calculation The correlation between the target authentication signal and the reference authentication signal is used to obtain a test statistic; and the test statistic is compared with a prescribed threshold to determine whether the carrier signal can pass the authentication (executed by the authentication device 50 at the receiving end).

In this embodiment, the processor 501 of the authentication device 50 at the transmitting end further performs the following operations: the carrier signal is transmitted in blocks in the form of data blocks.

In this embodiment, the processor 501 of the authentication device 50 at the transmitting end further performs the following operations: in each carrier signal, the sum of the signal length of the pilot signal and the signal length of the information signal is equal to the signal length of the carrier signal.

In this embodiment, the processor 501 of the authentication device 50 at the receiving end further performs the following operation: obtain a reference signal based on a key and a pilot signal by using a hash matrix.

In this embodiment, the processor 501 of the authentication device 50 at the receiving end further performs the following operation: if the test statistic is not less than a prescribed threshold, the carrier signal passes the authentication.

In this embodiment, the processor 501 of the authentication device 50 at the receiving end further performs the following operations: the specified threshold is obtained based on the statistical characteristics of the pilot signal and the preset upper limit of the false alarm probability.

In this implementation manner, it should be understood that the disclosed device may be implemented in other ways. For example, the device implementation described above is only illustrative, for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, for example, multiple units or components can be combined or can be Integrate into another system, or some features may be ignored, or not implemented. In another point, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be in electrical or other forms.

A unit described as a separate component may or may not be physically separated, and a component displayed as a unit may or may not be a physical unit, that is, it may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in the embodiment of the present invention may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

If the integrated unit is realized in the form of a software function unit and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the essence of the technical solution of the present invention or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a memory. Several instructions are included to make a computer device (which may be a personal computer, server or network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned memory includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk and other media that can store program codes.

This embodiment discloses a computer-readable storage medium. Those skilled in the art can understand that all or part of the steps in the various physical layer blind authentication methods in the above embodiments can be completed by instructing related hardware through programs (instructions) , the program (instruction) can be stored in a computer-readable memory (storage medium), and the memory can include: a flash disk, a read-only memory (English: Read-Only Memory, referred to as: ROM), a random access device (English: RandomAccess Memory, referred to as: RAM), disk or CD-ROM, etc.

Although the present invention has been specifically described above in conjunction with the drawings and embodiments, it should be understood that the above description does not limit the present invention in any form. Those skilled in the art can make modifications and changes to the present invention as required without departing from the true spirit and scope of the present invention, and these modifications and changes all fall within the scope of the present invention.

Claims (11)

1. A blind authentication method of frequency selective fading channel based on smoothing technique is a physical layer authentication method of wireless communication system with transmitting end and receiving end,

the method comprises the following steps:

the transmitting terminal transmits a carrier signal to a wireless channel, wherein the carrier signal comprises an authentication signal, a pilot signal and an information signal, the authentication signal is superposed to the pilot signal, and the wireless channel is a frequency selective fading channel with a plurality of paths;

the receiving end receives the carrier signal, sequentially carries out Blind Known Interference Cancellation (BKIC) processing on the carrier signal in each path of the frequency selective fading channel to obtain a target signal, carries out differential signal processing on the target signal to obtain a target authentication signal, and utilizes adjacent code elements to eliminate the pilot signal through a smoothing technology in the BKIC processing;

in the receiving end, obtaining a reference signal based on a secret key and the pilot signal, carrying out differential signal processing on the reference signal to obtain a reference authentication signal, and calculating the correlation between the target authentication signal and the reference authentication signal to obtain a test statistic; and is

Comparing the test statistic to a prescribed threshold to determine whether the carrier signal is capable of being authenticated.

2. The blind authentication method of claim 1, wherein:

the carrier signal is transmitted in blocks in the form of data blocks.

3. The blind authentication method of claim 2, wherein:

in each of the carrier signals, a sum of a signal length of the pilot signal and a signal length of the information signal is equal to a signal length of the carrier signal.

4. The blind authentication method of claim 1,

obtaining the reference signal based on the key and the pilot signal using a hash matrix.

5. The blind authentication method of claim 1,

if the test statistic is not less than the prescribed threshold, the carrier signal is authenticated.

6. The blind authentication method of claim 1,

the prescribed threshold is obtained based on statistical characteristics of the pilot signal and a preset false alarm probability upper limit.

7. A blind authentication device for frequency selective fading channel based on smoothing technique is characterized in that,

the method comprises the following steps:

a processor executing the memory-stored computer program to implement the blind authentication method of any one of claims 1 to 6; and

a memory.

8. A computer-readable storage medium, characterized in that,

the computer-readable storage medium stores at least one instruction that, when executed by a processor, implements the blind authentication method of any one of claims 1 to 6.

9. A blind authentication system of frequency selective fading channel based on smoothing technique is characterized in that,

a transmitting device that transmits a carrier signal including an authentication signal, a pilot signal, and an information signal to a wireless channel, the authentication signal being superimposed to the pilot signal, the wireless channel being a frequency selective fading channel having a plurality of paths; and

a receiving device, comprising: a first processing module, configured to receive the carrier signal, sequentially perform Blind Known Interference Cancellation (BKIC) processing on the carrier signal in each path of the frequency selective fading channel to obtain a target signal, perform differential signal processing on the target signal to obtain a target authentication signal, and in the BKIC processing, eliminate the pilot signal by using adjacent symbols through a smoothing technique; the second processing module is used for obtaining a reference signal based on a secret key and the pilot signal, carrying out differential signal processing on the reference signal to obtain a reference authentication signal, and calculating the correlation between the target authentication signal and the reference authentication signal subjected to differential signal processing to obtain a test statistic; and a decision module that compares the test statistic to a prescribed threshold to determine whether the carrier signal is authentic.

10. The authentication system according to claim 9,

the second processing module obtains the reference signal based on the key and the pilot signal using a hash matrix.

11. The blind authentication system of claim 9,

in the decision module, the predetermined threshold is obtained based on statistical characteristics of the pilot signal and a preset false alarm probability upper limit.