CN108173791B - Physical layer blind authentication method and system of time-varying fading channel based on smoothing technology - Google Patents
Physical layer blind authentication method and system of time-varying fading channel based on smoothing technology Download PDFInfo
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- CN108173791B CN108173791B CN201711347201.9A CN201711347201A CN108173791B CN 108173791 B CN108173791 B CN 108173791B CN 201711347201 A CN201711347201 A CN 201711347201A CN 108173791 B CN108173791 B CN 108173791B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03821—Inter-carrier interference cancellation [ICI]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/0202—Channel estimation
- H04L25/0224—Channel estimation using sounding signals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W12/00—Security arrangements; Authentication; Protecting privacy or anonymity
- H04W12/06—Authentication
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L2209/00—Additional information or applications relating to cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
- H04L2209/80—Wireless
Abstract
The invention discloses a physical layer blind authentication method of a time-varying fading channel based on a smoothing technology, which is characterized by comprising the steps that a transmitting end 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 time-varying fading channel; a receiving end receives a carrier signal, and performs Blind Known Interference Cancellation (BKIC) processing and differential signal processing on the carrier signal to obtain a target authentication signal, wherein in the BKIC processing, a pilot signal is eliminated by using adjacent code elements through a smoothing technology; in a receiving end, obtaining a reference signal based on a secret key and a pilot signal, carrying out differential signal processing on the reference signal to obtain a reference authentication signal, and calculating the correlation between a target authentication signal and the reference authentication signal to obtain test statistic; and comparing the test statistic with a prescribed threshold to determine whether the carrier signal can be authenticated.
Description
Technical Field
The invention relates to the technical field of wireless communication, in particular to a physical layer blind authentication method and a physical layer blind authentication system of a time-varying fading channel based on a smoothing technology.
Background
The authentication technology of the current physical layer mainly has three types, the first authentication technology is a spread spectrum technology (Auth-SS), the basic idea is to adopt the traditional direct sequence spread spectrum or frequency modulation technology, and because different pulses adopt different frequencies, certain bandwidth needs to be sacrificed when the authentication is realized by the technology. Furthermore, a key limitation of the Auth-SS technology is to allow only users with knowledge of the a priori knowledge about the spread spectrum technology to participate in the communication. Therefore, the application range of the technology is narrow.
The second is based on time division multiplexing authentication technology (Auth-TDM), and the basic idea is that the transmitting end periodically sends information signals and authentication signals alternately. The receiving end directly extracts expected authentication information after receiving the signal to realize the purpose of authenticating the signal. Auth-TDM is an authentication technique proposed in the early development of wireless communication, and has the advantages of simple operation and no need of preprocessing the authentication signal and information (possibly encryption for security reasons) before transmitting the signal. The authentication signal is independent of the information signal transmission, so a certain bandwidth needs to be occupied, and with the continuous increase of the amount of wireless information, the further improvement of the information privacy of a user and the continuous enhancement of an attack technology of an adversary, the security of the authentication technology is greatly challenged, and the requirements of the user cannot be met.
The third authentication technology is the authentication superposition technology (Auth-SUP), and the basic idea is to superpose the authentication signal on the information signal (the superposition mode can be arbitrary and is determined by the key), and then the information signal is simultaneously transmitted by the transmitting terminal, and the receiving terminal extracts the authentication signal in the superposed signal by using the key after receiving the signal, so as 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 signal transmission, puts forward a certain requirement on the signal processing capability of a transmitting end, is more complicated to realize than the Auth-TDM technology, and simultaneously transmits the authentication signal and the information signal, so that extra bandwidth is not occupied. At this time, since the authentication signal is superimposed in the information signal, the receiving end needs to extract the information after receiving the signal, the signal processing difficulty is higher than that of the Auth-TDM technology, but the concealment of the authentication information is higher than that of the Auth-TDM. In addition, since the authentication signal plays a role of noise for extracting the information signal, the SNR of the receiving end is correspondingly reduced, and the extraction of the information signal is adversely affected.
The existing Auth-TDM and Auth-SUP authentication techniques transmit another pilot signal in addition to the information signal and the authentication signal. The two authentication techniques require that the receiving end estimates the channel parameters and recovers the symbols after receiving the signals, and then extracts the authentication signals, and at this time, certain requirements are also provided for the signal processing capability of the receiving end.
In addition, Auth-TDM, Auth-SS and Auth-SUP all expose the fact that the Auth-TDM, Auth-SS and Auth-TDM technologies are more likely to attract the attention of other users, especially hostile users, in a scene compared with conventional signals which do not contain authentication information, the hostile users analyze, counterfeit or tamper with the signals, and a legal receiving end cannot authenticate the expected signals. In contrast, Auth-SUP authentication techniques are significantly more covert than Auth-SS and Auth-TDM. However, this advantage is based on the premise that the computing power of the adversary user has certain limitations, and once the computing power of the adversary user is increased, the authentication information is likely to be extracted or even destroyed.
It has to be mentioned that the existing Auth-SS technology and Auth-SUP technology degrade significantly in time-varying fading channel scenarios. However, the communication environment is more complex and the possibility of interference is higher and higher with the increasing number of wireless communication users, and with the increasing number of urban communication users and the continuous development of cities, a simple time-invariant fading channel is not enough to depict the current communication environment. Therefore, a wireless communication physical layer authentication technology based on a time-varying fading channel has to be considered to improve the security of wireless communication and meet the communication security requirements of users.
Disclosure of Invention
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method and a system for blind authentication of a physical layer of a time-varying fading channel based on a smoothing technique, which do not occupy an extra signal bandwidth, do not cause an authentication signal to be noise that affects extraction of an information signal from a carrier signal, and do not affect statistical characteristics of noise at a receiving end.
To this end, a first aspect of the present invention provides a physical layer blind authentication method for a time-varying fading channel based on a smoothing technique, which is a physical layer authentication method for wireless communication in a wireless communication system having a transmitting end and a receiving end, and includes: 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 time-varying fading channel; the receiving end receives the carrier signal, and performs Blind Known Interference Cancellation (BKIC) processing and differential signal processing on the carrier signal to obtain a target authentication signal, wherein in the BKIC processing, the pilot signal is cancelled by using adjacent code elements through a smoothing technique; 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 comparing the test statistic to a prescribed threshold to determine whether the carrier signal is authentic.
In the present invention, the authentication signal is superimposed on the pilot signal. Therefore, the signal-to-interference-and-noise ratio of the receiving end can not be influenced. The BKIC processing removes the pilot signal by a smoothing technique using adjacent symbols. In this case, the pilot signal can be canceled while avoiding estimating the channel.
In the physical layer 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. Thereby, manipulation of data is facilitated.
In the physical layer blind authentication method according to the first aspect of the present invention, 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.
In addition, in the physical layer 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 using a hash matrix. Therefore, the reference authentication signal is obtained by processing the reference signal, and whether the target authentication signal passes the authentication can be determined according to the correlation between the reference authentication signal and the target authentication signal.
In the physical layer blind authentication method according to the first aspect of the present invention, if the test statistic is not less than the predetermined threshold, the carrier signal is authenticated.
In the physical layer blind authentication method according to the first aspect of the present invention, the predetermined threshold is obtained based on a statistical characteristic of the pilot signal and a preset upper limit of a false alarm probability.
A second aspect of the present invention provides a physical layer blind authentication apparatus for a time-varying fading channel based on a smoothing technique, comprising a processor executing a computer program stored in the memory to implement the physical layer blind authentication method of any one of the above; and a memory.
A third aspect of the invention provides a computer-readable storage medium. The computer-readable storage medium stores at least one instruction that when executed by a processor implements the physical layer blind authentication method of any of the first aspects above.
The fourth aspect of the present invention provides a physical layer blind authentication system of a time-varying fading channel based on a smoothing technique, which includes a transmitting device that transmits a carrier signal to a wireless channel, where the carrier signal includes an authentication signal, a pilot signal and an information signal, the authentication signal is superimposed to the pilot signal, and the wireless channel is a time-varying fading channel; the receiving device comprises a first processing module, a second processing module and a decision module, wherein the first processing module receives the carrier signal, and performs Blind Known Interference Cancellation (BKIC) processing and differential signal processing on the carrier signal to obtain a target authentication signal, and in the BKIC processing, the pilot signal is cancelled by using adjacent code elements through a smoothing technology. The second processing module obtains a reference signal based on a secret key and the pilot signal, performs differential signal processing on the reference signal to obtain a reference authentication signal, calculates the correlation between the target authentication signal and the reference authentication signal to obtain a test statistic, and the judging module compares the test statistic with a specified threshold value to determine whether the carrier signal can pass authentication.
In the invention, a transmitting device of the physical layer blind authentication system superposes an authentication signal to a pilot signal. Therefore, extra transmission bandwidth resources can not be occupied. The BKIC processing of the receiving device of the physical layer blind authentication system utilizes adjacent symbols to eliminate the pilot signal by a smoothing technique. In this case, the receiving apparatus can cancel the pilot signal while avoiding estimating the channel.
In the physical layer 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. Therefore, the reference authentication signal is obtained by processing the reference signal, and whether the target authentication signal passes the authentication can be determined according to the correlation between the reference authentication signal and the target authentication signal.
In the physical layer blind authentication system according to the fourth aspect of the present invention, the predetermined threshold in the determination module is obtained based on statistical characteristics of the pilot signal and a preset upper limit of a false alarm probability.
Compared with the prior art, the implementation mode of the invention has the following beneficial effects:
compared with the existing Auth-SS, Auth-SUP and Auth-TDM, the invention realizes the authentication of the wireless communication physical layer without occupying extra signal bandwidth, and the authentication signal does not become noise which affects the extraction of the received signal and does not affect the statistical characteristic of the noise of the receiving end. The blind authentication technology provided by the invention processes a time-varying fading channel, and is more suitable for complex and changeable wireless communication environments in actual communication scenes. In addition, since the authentication signal is superimposed in the pilot signal, if the entirety of the signal obtained by superimposing the authentication signal and the pilot signal is used as the pilot signal for channel estimation, the accuracy of channel estimation can be improved.
Drawings
Fig. 1 is a signal transmission diagram illustrating a physical layer blind authentication method according to an embodiment of the present invention.
Fig. 2 is a schematic flow chart illustrating a physical layer blind authentication method according to an embodiment of the present invention.
Fig. 3 is a schematic diagram illustrating a structure of a signal transmitted by a transmitting end of a physical layer blind authentication method according to an embodiment of the present invention.
Fig. 4 is a schematic diagram illustrating a processing flow of Blind Known Interference Cancellation (BKIC) at a receiving end of a physical layer blind authentication method according to an embodiment of the present invention.
Fig. 5 is a schematic diagram illustrating a signal processing module at a transmitting end of a physical layer blind authentication system according to an embodiment of the present invention.
Fig. 6 is a schematic diagram illustrating a receiving end signal processing module of a physical layer blind authentication system according to an embodiment of the present invention.
Fig. 7 is a schematic structural diagram illustrating a physical layer blind authentication device according to an embodiment of the present invention.
Detailed Description
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same components are denoted by the same reference numerals, and redundant description thereof is omitted. The drawings are schematic and the ratio of the dimensions of the components and the shapes of the components may be different from the actual ones.
It should be noted that the terms "first", "second", "third" and "fourth", etc. in the description and claims of the present invention and the above-mentioned drawings are used for distinguishing different objects and are not used for describing a specific order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.
The embodiment discloses a physical layer blind authentication method, equipment and a system of a time-varying fading channel based on a smoothing technology, and relates to the physical layer authentication method, the equipment and the system of wireless communication of a wireless communication system with a transmitting end and a receiving end. That is, the present embodiment discloses a physical layer blind authentication method, device and system for a wireless communication time-varying fading channel based on a smoothing technique. Which can more accurately perform physical layer authentication. The following detailed description is made with reference to the accompanying drawings.
Fig. 1 is a signal transmission diagram illustrating a physical layer blind authentication method according to an embodiment of the present invention.
In the present embodiment, as shown in fig. 1, the physical layer blind authentication method for the time-varying fading channel in wireless communication based on the smoothing technique is based on a general signal transmission model. In the signal transmission model, 4 users are included, wherein a sender (a transmitting end) is a legal sender, the transmitting end transmits signals to a legal receiver, namely a receiving end, and the other two receivers are a monitoring user and an enemy user in the system respectively. Once an adversary user finds that there may be authentication information in the signal sent by the transmitting end, the adversary user will analyze the signal and attempt to extract, destroy, or even tamper with the authentication information. However, the present embodiment is not limited to this, and the number of the transmitting ends may be two or more, the number of the legitimate receivers may be two or more, and the number of the listening users and the number of the enemy users may be two or more.
In the present embodiment, it is assumed that the transmitting end and the receiving end have a key for authentication in common, so that the receiving end can extract authentication information from a signal transmitted by the transmitting end using the key. The authentication signal includes authentication information. In this embodiment, the carrier signal contains the authentication signal and the regular signal does not contain the authentication signal. The monitoring user has no knowledge about the authentication method, and although the signal sent by the transmitting terminal can be received and recovered, the signal cannot be deeply analyzed, and the authentication process is not influenced. An adversary user may perceive the presence of the authentication signal by analyzing the characteristics of the signal and intend to corrupt the authentication signal.
In this embodiment, the transmitting end in the signal model may include a base station or a user equipment. A base station (e.g., access point) can refer to a device in an access network that communicates over the air-interface, through one or more sectors, with wireless terminals. The base station may be configured to interconvert received air frames and IP packets as a router between the wireless terminal and the rest of the access network, which may include an Internet Protocol (IP) network. The base station may also coordinate management of attributes for the air interface. For example, the Base Station may be a Base Transceiver Station (BTS) in GSM or CDMA, a Base Station (NodeB) in WCDMA, or an evolved Node B (NodeB or eNB or e-NodeB) in LTE, and this embodiment is not limited thereto.
The user Device may include, but is not limited to, various electronic devices such as a smart Phone, a notebook computer, a Personal Computer (PC), a Personal Digital Assistant (PDA), a Mobile Internet Device (MID), a wearable Device (e.g., a smart watch, a smart bracelet, and smart glasses), wherein an operating system of the user Device may include, but is not limited to, an Android operating system, an IOS operating system, a Symbian operating system, a blackberry operating system, a Windows Phone8 operating system, and the like, and the present embodiment is not limited thereto.
In this embodiment, the transmitting end in the signal model transmits a signal to the receiving end through a wireless channel, wherein the receiving end may include a base station. A base station (e.g., access point) can refer to a device in an access network that communicates over the air-interface, through one or more sectors, with wireless terminals. The base station may be configured to interconvert received air frames and IP packets as a router between the wireless terminal and the rest of the access network, which may include an Internet Protocol (IP) network. The base station may also coordinate management of attributes for the air interface. For example, the Base Station may be a Base Transceiver Station (BTS) in GSM or CDMA, a Base Station (NodeB) in WCDMA, or an evolved Node B (NodeB or eNB or e-NodeB) in LTE, and this embodiment is not limited thereto.
The receiving end may further include a user Device, where the user Device may include but is not limited to various electronic devices such as a smart Phone, a notebook Computer, a Personal Computer (PC), a Personal Digital Assistant (PDA), a Mobile Internet Device (MID), a wearable Device (e.g., a smart watch, a smart bracelet, and smart glasses), and the operating system of the user Device may include but is not limited to an Android operating system, an IOS operating system, a Symbian operating system, a blackberry operating system, a Windows Phone8 operating system, and the like, and this embodiment is not limited.
The embodiment discloses a physical layer blind authentication method of a wireless communication time-varying fading channel based on a smoothing technology. Fig. 2 is a schematic flow chart illustrating a physical layer blind authentication method according to an embodiment of the present invention. Fig. 3 is a schematic diagram illustrating a structure of a signal transmitted by a transmitting end of a physical layer blind authentication method according to an embodiment of the present invention.
In the present embodiment, the physical layer blind authentication method for a time-varying fading channel in wireless communication based on the smoothing technique is a physical layer authentication method for wireless communication in a wireless communication system having a transmitting end and a receiving end. Based on the signal transmission model described above, as shown in fig. 2, 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. The wireless channel is a time-varying fading channel (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. Thus, the superposition of the authentication signal to the pilot signal may avoid occupying additional signal bandwidth.
In this embodiment, the information signal contains information to be communicated by the transmitting end user. The carrier signal sent by the transmitting terminal is transmitted in blocks in the form of data blocks. Each block of the carrier signal comprises a pilot part and an information part. The pilot portion includes an authentication signal and a pilot signal. The information part comprises an information signal. In addition, the carrier signal is transmitted in blocks in the form of data blocks, which facilitates manipulation of the data.
In this embodiment, the signal length of the authentication signal or the pilot signal is a first length, the signal length of the information signal is a second length, the length of each carrier signal is a total length, and 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, i.e., the sum of the first length and the second length is equal to the total length.
In this embodiment, the authentication signal is obtained by using the pilot signal and the secret key, that is, the pilot signal and the secret key obtain the authentication signal by using the hash matrix. And superposing the obtained authentication signal to a pilot signal to obtain a pilot part of each carrier signal, wherein the signal expression of the pilot part is as follows:
mi＝ρspi+ρtti(1)
in the above signal expression (1) of the pilot part,
and
a factor is assigned to the power of the pilot information and the authentication signal. Assuming that the authentication signal and the pilot signal are independent of each other, there are
In this embodiment, the pilot part signal and the information part signal are combined to form a carrier signal for each block.
In addition, in the present embodiment, the transmission channel of the carrier signal is a radio channel and is a time-varying fading channel. The expression of the carrier signal after passing through the time-varying fading channel is as follows:
yiL+k＝hiL+kxiL+k+niL+k(2)
in the present embodiment, the channel response h of the time-varying fading channeliL+kCompliance with0Mean variance of
Complex gaussian distribution. In addition, hiL+kIs characterized as a first order gaussian markov process, the expression of which is as follows:
hiL+k＝ahiL+k-1+ωiL+k(3)
in general, a ∈ [0, 1] in expression (3) is a fading correlation coefficient, which is determined by the channel doppler spread and the transmission bandwidth, in particular, a value of a is small to indicate fast fading, and a value of a is large to indicate slow fading.
In this embodiment, the physical layer blind authentication method further includes that the receiving end receives the carrier signal, and performs Blind Known Interference Cancellation (BKIC) processing and differential signal processing on the carrier signal to obtain a target authentication signal. In the BKIC process, the pilot signal is canceled by a smoothing technique using adjacent symbols (step S102).
In this embodiment, the receiving end receives the carrier signal. The carrier signal contains a pilot part and an information part. The physical layer blind authentication method according to the present embodiment is mainly to process a pilot portion of a carrier signal at a receiving end. The expression for the pilot part of the carrier signal received at the receiving end is as follows:
yk＝hk(ρspk+ρttk)+nk，iL≤k≤iL+L1(4)
in the present embodiment, the following processing for the carrier signal refers to processing for the pilot portion of the carrier signal.
In step S102, the receiving end receives the carrier signal, and performs Blind Known Interference Cancellation (BKIC) processing on the carrier signal to obtain a target signal. Therein, the Blind Known Interference Cancellation (BKIC) process is to cancel the pilot signal in the carrier signal by a smoothing technique using adjacent symbols. The elimination of the pilot signal in the carrier signal usually requires the estimation of the channel condition, and if the channel response cannot be estimated effectively, the pilot signal in the carrier signal is difficult to eliminate. Blind known interference cancellation methods may cancel the pilot signal while avoiding estimating the channel.
In this embodiment, the carrier signal received by the receiving end may or may not include the authentication signal. The carrier signal is set to include the authentication information as a first condition, and the carrier signal is set to include no authentication information as a second condition.
Fig. 4 is a schematic diagram illustrating a processing flow of Blind Known Interference Cancellation (BKIC) at a receiving end of a physical layer blind authentication method according to an embodiment of the present invention.
In the present embodiment, as shown in fig. 4, the BKIC process includes determining an expression for each symbol under different conditions (step S401) and estimating a target signal using the expression for the symbol (step S402).
In step S401, an expression for each symbol under different conditions is determined.
Under a first condition, the expression of each code element is as follows:
k∈{1，2，…，L1-1}
under the second condition, the expression for each symbol is as follows:
as can be seen from the above formula, there is correlated noise between adjacent symbols, the correlated noise in expression (5) cannot be corrected by the ordinary noise whitening technique, and the correlated noise needs to be removed by step S402, and h is estimatedkρttk+nk。
In step S402, a target signal is estimated using the expression of the symbol. The above expression (5) is expressed as follows:
the estimation results can be obtained as follows:
wherein ε in the expression (10)kIs due to the residual signal, epsilon, generated in the process of interference elimination by the BKIC modulekCan be modeled as a gaussian distribution. For slow fading, (a → 1), εkHas a small variance of (a), so that y can be expressedkOfkRemoving to obtain an estimated hkρttk+nkI.e. to obtain the estimated target signal without the pilot signal.
In step S102, the carrier signal is processed by BKIC to obtain a target signal, and the target signal is processed by a differential signal to obtain a target authentication signal.
In the present embodiment, the method of differential signal processing is as follows:
under the first condition, the expression of differential signal processing is as follows:
wherein ΔkFor residual signals, it can be modeled approximately as a 0 mean variance of
Gaussian random variable of (2).
Under the second condition, the expression of differential signal processing is as follows:
wherein
Is a zero mean complex gaussian random variable.
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 a correlation between the target authentication signal and the reference authentication signal to obtain a test statistic (step S103).
In step S103, obtaining the reference signal based on the key and the pilot signal means obtaining the reference signal from the key and the pilot signal using the hash matrix. Therefore, the reference authentication signal is obtained by processing the reference signal, and whether the target authentication signal passes the authentication can be determined according to the correlation between the reference authentication signal and the target authentication signal.
In step S103, the reference signal is subjected to differential signal processing to obtain a reference authentication signal, the correlation between the target authentication signal and the reference authentication signal is calculated to obtain a test statistic, and a next determination can be made based on the value of the test statistic.
In the present embodiment, differential signal processing is performed on a reference signal to obtain a reference authentication signal. The method of differential signal processing is the same as the differential processing method in step S102 described above.
In step S102, the carrier signal received by the receiving end may include an authentication signal, and it is assumed that the carrier signal includes the authentication information as a first condition and the carrier signal does not include the authentication signal as a second condition.
At a receiving end, the carrier signal is processed by Blind Known Interference Cancellation (BKIC) and differential signal processing to obtain a target authentication signal. At the receiving end, a reference signal is obtained based on the key and the pilot signal. The reference signal is subjected to Differential (DP) signal processing to obtain a reference authentication signal. The rule for generating the reference signal by the hash matrix, the key and the pilot signal of the receiving end is the same as the rule for generating the authentication signal by the hash matrix, the key and the pilot signal of the transmitting 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 reference authentication signal being included in the target authentication signal; the second condition may be expressed as the reference authentication signal not being included in the target authentication signal.
In this embodiment, the physical layer blind authentication method further includes comparing the test statistic with a predetermined threshold value to determine whether the carrier signal can be authenticated (step S104).
In step S104, if the test statistic is not less than the predetermined threshold, it is determined that the carrier signal passes the authentication; if the test statistic is less than the prescribed threshold, the carrier signal is determined to have failed authentication.
In this embodiment, if the test statistic is not less than the predetermined threshold, the carrier signal includes the reference authentication signal, that is, the carrier signal passes the authentication; if the test statistic is less than the prescribed threshold, the carrier signal does not contain the reference authentication signal, i.e. the carrier signal is not authenticated.
In the present embodiment, the predetermined threshold is obtained by assuming the verification condition, and the first condition and the second condition are the first condition H of the assumption verification condition, respectively1And a second condition H0。
In the present embodiment, the first condition H1The test statistic is expressed as follows:
second Condition H0The test statistic is expressed as follows:
wherein the content of the first and second substances,
is 0 mean variance of
Gaussian random variable of (2). Phi is aiIs 0 mean variance of
Gaussian random variable of (2).
In addition, a threshold value is defined
Is composed of (tau)i|H0) Distribution-dependent false alarm probability epsilonFAThe decision, expressed as follows:
wherein (tau)i|H0) Is the test statistic obtained under the second condition, i.e., the statistical characteristic of the pilot signal. Thus, the prescribed threshold may be derived based on the statistical properties of the pilot signal and a preset upper limit of the false alarm probability.
In addition, in this embodiment, if the identity of the transmitting end is authenticated, the authentication signal can be used as an additional pilot signal to recover the signal. Thereby, the performance of signal symbol recovery and the performance of channel response estimation can be improved.
In addition, in the present embodiment, the authentication signal is superimposed on the pilot signal, thereby avoiding adverse effects on the extraction of the normal signal. Thereby, the reduction of the signal to interference plus noise ratio (SINR) at the receiving end is avoided.
In the embodiment, the physical layer blind authentication method of the wireless communication time-varying fading channel based on the smoothing technology does not need to occupy extra signal bandwidth. In addition, when the information signal is extracted from the carrier signal at the receiving end, the authentication signal does not become noise of the information signal, that is, the authentication signal does not affect the extraction of the information signal. The authentication signal does not affect the statistical properties of the noise at the receiving end.
In the embodiment, the physical layer blind authentication method processes a time-varying fading channel, and is more suitable for a complex and variable wireless communication environment in an actual communication scene. In addition, the authentication signal is superposed in the pilot signal, and if the entirety of the signal obtained by superposing the authentication signal and the pilot signal is used as the pilot signal for channel estimation, the accuracy of channel estimation can be improved.
The embodiment discloses a physical layer blind authentication system of a wireless communication time-varying fading channel based on a smoothing technology. Fig. 5 is a schematic diagram illustrating a signal processing module at a transmitting end of a physical layer blind authentication system according to an embodiment of the present invention. Fig. 6 is a schematic diagram illustrating a receiving end signal processing module of a physical layer blind authentication system according to an embodiment of the present invention.
In the present embodiment, as shown in fig. 5, the physical layer blind authentication system includes a transmitting device 20. The transmitting apparatus 20 comprises a first generating module 201, a second generating module 202 and a synthesizing module 203.
In the present embodiment, as shown in fig. 5, the first generation module 201 generates the authentication signal, that is, the key and the pilot signal pass through the first generation module 201 to generate the authentication signal. The first generation module 201 includes a hash matrix. The authentication signal is obtained by using a hash matrix for the key and the pilot signal. Wherein, the obtained authentication signal has the same signal length as the pilot signal.
In this embodiment, the second generation module 202 generates the pilot portion of the carrier signal, as shown in fig. 5. I.e. the authentication signal is loaded onto the pilot signal by the second generating module 202, generating the pilot part of the carrier signal. The expression of the pilot part of the carrier signal is formula (1), and in addition, the length of the pilot part of the carrier 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 the carrier signal, that is, the pilot part and the information part of the carrier signal are combined together by the synthesis module 203 to generate the carrier signal. The information part of the carrier signal is an information signal.
In this embodiment, the carrier signals are transmitted in blocks of data, each block of carrier signals comprising a pilot portion and an information portion, the sum of the signal length of the authentication signal or pilot signal and the signal length of the information signal being equal to the length of each block of carrier signals. In addition, the carrier signal is transmitted in blocks in the form of data blocks, which facilitate manipulation of the data.
In the present embodiment, the carrier signal generated by the transmitting apparatus 20 at the transmitting end reaches the receiving apparatus 30 at the receiving end through a wireless channel. In addition, the wireless channel is a time-varying fading channel.
In the present embodiment, the physical layer blind authentication system further includes a receiving device 30, and the receiving device 30 includes a first processing module, a second processing module, and a determining module.
In this embodiment, the first processing module comprises a Blind Known Interference Cancellation (BKIC) module 301. After the carrier signal passes through a Blind Known Interference Cancellation (BKIC) module 301, the pilot signal in the carrier signal is cancelled.
In the present embodiment, the Blind Known Interference Cancellation (BKIC) module 301 employs a BKIC processing method of canceling a pilot signal by using adjacent symbols in step S102 and using a smoothing technique. As shown in fig. 4, the BKIC process includes determining an expression for each symbol under different conditions (step S401) and estimating a target signal using the expression for the symbol (step S402).
In this embodiment, as shown in fig. 6, the first processing module further includes a Difference (DP) processing module 302. The DP processing module 302 employs 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. Thereby eliminating h in the target authentication signalkI.e. the influence of the cancellation channel on the carrier signal.
In the DP processing block 302, under the first condition, the expression of the differential signal processing is formula (11), where ΔkFor residual signals, it can be modeled approximately as a 0 mean variance of
Gaussian random variable of (2). Under a second condition, the expression of differential signal processing is formula (12), where
Is a zero mean complex gaussian random variable.
In this embodiment, as shown in fig. 6, the second processing module further includes a hash matrix processing module 303. The pilot signal and the key are passed through a hash matrix processing module 303 to obtain a reference signal. The hash matrix processing module 303 uses the method of generating the reference signal in step S103, and 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 Difference (DP) processing module 304. The Difference (DP) processing module 304 performs difference signal processing on the reference signal to obtain a reference authentication signal. The DP processing block 304 employs 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 operation module 305 is used to calculate the test statistic of the target authentication signal and the reference authentication signal. The calculation method used by the operation 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 authentication, i.e., whether the carrier signal passes authentication, by comparing the test statistic with a prescribed threshold.
In this embodiment, the predetermined threshold in the determination module 306 is obtained based on the statistical characteristics of the pilot signal and a preset upper limit of the false alarm probability. The predetermined threshold value is calculated in step S103.
The embodiment discloses a physical layer blind authentication device 50 of a wireless communication time-varying fading channel based on a smoothing technology. Fig. 7 is a schematic structural diagram illustrating a basic physical layer blind authentication device according to 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 the present embodiment, as shown in fig. 7, the authentication device 50 includes a processor 501 and a memory 502. The processor 501 and the memory 502 are connected to a communication bus, respectively. The memory 502 may be a high-speed RAM memory or a non-volatile memory (non-volatile memory). Those skilled in the art will appreciate that the configuration of the authentication device 50 shown in fig. 7 is not intended to limit the present invention, and may be a bus configuration, a star configuration, a combination of more or fewer components than those shown in fig. 7, or a different arrangement of components.
The processor 501 is a control center of the authentication device 50, and may be a Central Processing Unit (CPU), and the processor 501 is connected to various parts of the entire authentication device 50 by using various interfaces and lines, and executes or executes software programs and/or modules stored in the memory 502 and calls program codes stored in the memory 502 to perform the following operations:
the transmitting end transmits a carrier signal comprising an authentication signal superimposed to a pilot signal, a pilot signal and an information signal to a wireless channel, which is a time-varying fading channel (performed by the authentication device 50 of the transmitting end).
A receiving end receives a carrier signal, and performs Blind Known Interference Cancellation (BKIC) processing and differential signal processing on the carrier signal to obtain a target authentication signal, wherein in the BKIC processing, a pilot signal is eliminated by using adjacent code elements through a smoothing technology; in a receiving end, obtaining a reference signal based on a secret key and a pilot signal, carrying out differential signal processing on the reference signal to obtain a reference authentication signal, and calculating the correlation between a target authentication signal and the reference authentication signal to obtain test statistic; and compares the test statistic with a prescribed threshold value to determine whether the carrier signal can pass authentication (performed by the authentication device 50 at the receiving end).
In the present 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 the present embodiment, the processor 501 of the authentication device 50 at the transmitting end further performs the following operations: 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 the present embodiment, the processor 501 of the authentication device 50 on the receiving side further performs the following operations: a reference signal is obtained based on the key and the pilot signal using a hash matrix.
In the present embodiment, the processor 501 of the authentication device 50 on the receiving side further performs the following operations: if the test statistic is not less than the prescribed threshold, the carrier signal is authenticated.
In the present embodiment, the processor 501 of the authentication device 50 on the receiving side further performs the following operations: the prescribed threshold is obtained based on the statistical properties of the pilot signal and a preset upper limit of the false alarm probability.
In this embodiment, it should be understood that the disclosed apparatus may be implemented in other ways. For example, the above-described device embodiments are merely illustrative, and for example, the division of the units is merely a logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of some interfaces, devices or units, and may be an electric or other form.
Units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, each functional unit in the embodiments of the present invention may be integrated into one processing unit, each unit may exist alone physically, or two or more units may be integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable memory. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a memory and includes several instructions for causing a computer device (which may be a personal computer, a server, a network device, or the like) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned memory comprises: a U-disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic or optical disk, and other various media capable of storing program codes.
The present embodiment discloses a computer readable storage medium, and those skilled in the art can understand that all or part of the steps in the various physical layer blind authentication methods of the foregoing embodiments can be implemented by a program (instructions) to instruct related hardware, where the program (instructions) can be stored in a computer readable memory (storage medium), where the memory can include: flash Memory disks, Read-Only memories (ROMs), Random Access Memories (RAMs), magnetic or optical disks, and the like.
While the invention has been specifically described above in connection with the drawings and examples, it will be understood that the above description is not intended to limit the invention in any way. Those skilled in the art can make modifications and variations to the present invention as needed without departing from the true spirit and scope of the invention, and such modifications and variations are within the scope of the invention.
Claims (11)
1. A physical layer blind authentication method of time-varying 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 time-varying fading channel;
the receiving end receives the carrier signal, and performs blind known interference elimination processing and differential signal processing on the carrier signal to obtain a target authentication signal, wherein in the blind known interference elimination processing, the pilot signal is eliminated by using adjacent code elements through a smoothing technology;
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 physical layer blind authentication method of claim 1, wherein:
the carrier signal is transmitted in blocks in the form of data blocks.
3. The physical layer blind authentication method of claim 2,
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 physical layer blind authentication method of claim 1,
obtaining the reference signal based on the key and the pilot signal using a hash matrix.
5. The physical layer blind authentication method of claim 1,
if the test statistic is not less than the prescribed threshold, the carrier signal is authenticated.
6. The physical layer 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 physical layer blind authentication device of a time-varying fading channel based on a smoothing technique is characterized in that,
the method comprises the following steps:
a processor executing a memory-stored computer program to implement the physical layer blind authentication method of any one of claims 1 to 6; and
the 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 physical layer blind authentication method of any of claims 1 to 6.
9. A physical layer blind authentication system of a time-varying fading channel based on a smoothing technique is characterized in that,
transmitting means for transmitting a carrier signal to a wireless channel, the carrier signal comprising an authentication signal, a pilot signal and an information signal, the authentication signal being superimposed to the pilot signal, the wireless channel being a time-varying fading channel; and
a receiving device, comprising: a first processing module, configured to receive the carrier signal, and perform blind known interference cancellation processing and differential signal processing on the carrier signal to obtain a target authentication signal, where the pilot signal is cancelled by a smoothing technique using adjacent symbols in the blind known interference cancellation processing; 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 physical layer blind authentication system of claim 9,
the second processing module obtains the reference signal based on the key and the pilot signal using a hash matrix.
11. The physical layer 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.
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