Differential Channel Estimation Method and Device for Quadratic Two-Way Feedback of Non-Reciprocal Channels

Abstract

The present application discloses a method for differential channel estimation of a non-reciprocal channel with secondary two-way feedback, which relates to communication technologies and includes: transmitting signals through the reverse channel, sending random pilots from the target node to the source node, and after receiving the random pilot information, the source node only amplifies the received information and forwards it back to the target node; transmitting signals through the reverse channel, sending regular pilots from the target node to the source node, and after receiving the regular pilots, the source node performs channel estimation through LMMSE. After obtaining the CSI of the reverse channel, the source node encodes the received signals using the channel estimation result and feeds them back to the target node through the forward channel. The method of the present application applies physical layer security technology (Physical Layer Security, PLS) in the channel estimation stage (channel estimation, CE) of a communication system to solve the problem of secure communication.

Description

Technical Field

[0001] This application relates to the field of communication technologies, and in particular, to a method and device for second bidirectional feedback differential channel estimation of a non-reciprocal channel. Background Art

[0002] Currently, the security of the communication link between space-based information systems such as communication satellites and the ground still relies on traditional security strategies, which are mainly solved by encryption and decryption methods in the network layer and above protocol layers. With the enhancement of computing power, especially the potential effect of quantum theory operations, this algorithm that simply relies on computational complexity to ensure information security is becoming increasingly unreliable, posing a severe challenge to the existing encryption system.

[0003] Physical layer security technology is a new type of confidentiality scheme based on information theory rather than simply relying on computational complexity. This technology starts from the physical layer with rich natural characteristics of wireless signals and explores a new type of secure transmission mechanism based on the complexity and randomness of air interface signals and the uniqueness and reciprocity of legitimate channels. Different from traditional security schemes, physical layer security technology uses (rather than avoids) the characteristics of wireless transmission to essentially resolve the information leakage risk caused by the openness of air interface signals, thereby providing more reliable confidentiality capabilities.

[0004] Differential channel estimation technology is one of the key technologies of physical layer security technology. This technology aims to improve the channel estimation performance of legitimate nodes as much as possible during the channel estimation stage, while deteriorating the channel state information estimation performance of eavesdropping nodes, so as to maximize the difference between the two. Currently, the focus of differential channel estimation work lies in the "differential CE method based on double feedback calculation" and the "differential CE method based on bidirectional calculation". The core idea of the "differential CE method based on double feedback calculation" is to reasonably design the precoding matrix of artificial noise according to the channel estimation information fed back by the target node in the first stage of channel estimation. If the CSI of the eavesdropping channel is known, the artificial noise can be directed to the eavesdropping node, thereby degrading the quality of the signal it receives without affecting the target node. At the same time, since the introduced artificial noise will consume the transmission power of the security signal, it will also lead to a decrease in the received signal-to-noise ratio of the target node or an increase in the total device power consumption. The core idea of the "differential CE method based on bidirectional calculation" is that the target node sends a pilot sequence to the source node through the reverse channel. The source node obtains the CSI of the reverse channel through CE and, according to the reciprocity of the channel, performs Hermite transformation on the reverse channel CSI to obtain the CSI of the forward channel. During this process, the eavesdropping channel only receives the pilot sequence transmitted by the target node and cannot carry out CE work because it cannot obtain the pilot sequence of the forward channel, so it cannot obtain the CSI of the eavesdropping channel.

[0005] In the traditional differential channel estimation scheme, the "differential CE method based on double feedback calculation" introduces additional artificial noise to deteriorate the estimation performance of the eavesdropping node on the CSI, which increases the power consumption cost of the communication system and there is a problem of introducing additional artificial noise to increase the communication power consumption. The "differential CE method of two-way calculation" is only applicable to the case of reciprocal channels. For the scenario of non-reciprocal channels, how to implement a low-power differential channel estimation scheme that the eavesdropping node cannot utilize any pilot information becomes a challenging problem. Summary of the Invention

[0006] In the channel estimation stage (channel estimation, CE) of the communication system in the embodiments of the present application, physical layer security technology (Physical Layer Security, PLS) is applied to solve the secure communication problem. For non-reciprocal channels, a quadratic two-way feedback differential channel estimation method for non-reciprocal channels is proposed to solve the problem of realizing low-power secure communication transmission in the case of non-reciprocal channels.

[0007] The embodiments of the present application provide a quadratic two-way feedback differential channel estimation method for non-reciprocal channels, which is applied to a communication system including a source node, a target node and an eavesdropping node. Among them, n s sub-arrays are configured at the source node, n d sub-arrays are configured at the target node and n e sub-arrays are configured at the eavesdropping node. During the process of the source node sending data to the target node, the channel through which the data passes is defined as the first forward channel; during the process of the target node sending data to the source node, the channel through which the data passes is defined as the reverse channel; during the process of the eavesdropping node sending data to the source node, the channel through which the data passes is defined as the second forward channel. The quadratic two-way feedback differential channel estimation method includes the following steps:

[0008] Utilize the reverse channel to transmit signals. The target node sends random pilots to the source node. After receiving the random pilot information, the source node only amplifies the received information and forwards it back to the target node;

[0009] Utilize the reverse channel to transmit signals. The target node sends regular pilots to the source node. After receiving the regular pilots, the source node performs channel estimation through LMMSE. After obtaining the CSI of the reverse channel, the source node encodes the received signals using the channel estimation results and feeds them back to the target node through the forward channel.

[0010] Optionally, the target node sending random pilots to the source node, and the source node only amplifying the received information and forwarding it back to the target node after receiving the random pilot information includes:

[0011] Use the target node to send a random pilot training sequence signal

[0012] The source node receives the signal X d1 After passing through the reverse channel H ds The transmitted signal is Y1 = H ds X d1 + U1, and the signal Y1 is amplified by α to obtain the signal X s1 = αY1, and it is sent to the target node;

[0013] At the target node, the signal X is received s1 After passing through the reverse channel H ds The transmitted signal After that, H sd H ds Is used as the equivalent channel in the feedback process;

[0014] The target node uses the LMMSE estimation method to estimate the equivalent channel estimation of the two-way feedback process.

[0015] Optionally, the target node sends a regular pilot to the source node. After receiving the regular pilot, the source node performs channel estimation through LMMSE to obtain the CSI of the reverse channel, including:

[0016] Use the target node to send a regular pilot training sequence signal

[0017] The source node receives the signal X d2 After passing through the reverse channel H ds The transmitted signal Y2 = H ds X d2 + U2, and then the reverse channel H is estimated through LMMSE ds Calculation to obtain the reverse channel estimation

[0018] The source node uses the reverse channel estimation To encode the pilot sequence to obtain the feedback transmission signal

[0019] The target node receives the signal X s2 After passing through the first forward channel H sd The transmitted signal After that, Is used as the equivalent channel in the feedback process;

[0020] The target node uses the LMMSE estimation method to estimate the equivalent channel estimation of the two-way feedback process.

[0021] Optionally, it further includes:

[0022] The target node uses the equivalent channel estimation in the first phase and the equivalent channel value in the second phase to estimate the first forward channel H sd .

[0023] An embodiment of the present application also proposes a quadratic two-way feedback differential communication system for non-reciprocal channels, including a source node, a target node, and an eavesdropping node. At the source node, n s sub-arrays are configured, n d sub-arrays are configured at the target node, and n e sub-arrays are configured at the eavesdropping node. During the process of the source node sending data to the target node, the channel through which the data passes is defined as the first forward channel; during the process of the target node sending data to the source node, the channel through which the data passes is defined as the reverse channel; during the process of the eavesdropping node sending data to the source node, the channel through which the data passes is defined as the second forward channel, where:

[0024] Using the reverse channel to transmit a signal, the target node sends a random pilot to the source node. After receiving the random pilot information, the source node only amplifies the received information and forwards it back to the target node;

[0025] Using the reverse channel to transmit a signal, the target node sends a conventional pilot to the source node. After receiving the conventional pilot, the source node performs channel estimation through LMMSE. After obtaining the CSI of the reverse channel, the source node encodes the received signal using the channel estimation result and feeds it back to the target node through the forward channel.

[0026] An embodiment of the present application also proposes a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the quadratic two-way feedback differential channel estimation method as described above are implemented.

[0027] An embodiment of the present application applies physical layer security technology (Physical Layer Security, PLS) in the channel estimation stage (channel estimation, CE) of the communication system to solve the problem of secure communication. For non-reciprocal channels, the method of the present application solves the problem of realizing low-power secure communication transmission in the case of non-reciprocal channels.

[0028] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features, and advantages of the present application more obvious and understandable, the following specifically illustrates the specific implementation manners of the present application. Description of the Drawings

[0029] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, throughout the drawings, the same reference numerals are used to denote the same components. In the drawings:

[0030] Figure 1 This is an example of a communication mechanism for the secondary two-way feedback differential channel estimation method of the embodiment of the present application;

[0031] Figure 2 This is the simulation result of the performance curve of the channel estimation error verification example of the secondary two-way feedback differential channel estimation method of the present application. Detailed implementation manners

[0032] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0033] An embodiment of the present application provides a secondary two-way feedback differential channel estimation method for a non-reciprocal channel, which is applied to a communication system including a source node, a target node, and an eavesdropping node. As Figure 1 shown, where n s sub-arrays are configured at the source node, n d sub-arrays are configured at the target node, and n e sub-arrays are configured at the eavesdropping node. During the process of the source node sending data to the target node, the channel through which the data passes is defined as the first forward channel H sd ; during the process of the target node sending data to the source node, the channel through which the data passes is defined as the reverse channel H ds ; during the process of the eavesdropping node sending data to the source node, the channel through which the data passes is defined as the second forward channel H se。This application considers passive attacks launched by eavesdropping nodes, so there is no situation where the source node receives information sent by the eavesdropping node. The target node sends a random pilot during the first two-way feedback process to obtain the product of the forward and reverse channel state information, and sends a conventional pilot during the second two-way feedback process. During the forward channel estimation process, the CSI of the reverse channel estimation is used to scramble the conventional pilot at the baseband to achieve the effect of confusion. The target node can obtain the forward channel CSI based on the linear minimum mean square error (LMMSE) algorithm according to the two two-way feedback processes, while the eavesdropping node cannot obtain any useful information. In some examples, the quadratic two-way feedback differential channel estimation method of the embodiments of this application includes the following steps:

[0034] Using the reverse channel to transmit signals, the target node sends a random pilot to the source node. After receiving the random pilot information, the source node only amplifies the received information and forwards it back to the target node.

[0035] Using the reverse channel to transmit signals, the target node sends a conventional pilot to the source node. After receiving the conventional pilot, the source node performs channel estimation through LMMSE. After obtaining the CSI of the reverse channel, the source node encodes the received signal using the channel estimation result and feeds it back to the target node through the forward channel.

[0036] The embodiments of this application apply physical layer security technology (PLS) in the channel estimation stage (channel estimation, CE) of the communication system to solve the problem of secure communication. For non-reciprocal channels, the method of this application solves the problem of realizing low-power secure communication transmission in the case of non-reciprocal channels.

[0037] In some embodiments, the target node sending a random pilot to the source node, and after receiving the random pilot information, the source node only amplifying the received information and forwarding it back to the target node includes:

[0038] Using the target node to send a random pilot training sequence signal

[0039] The source node receives the signal X d1 After passing through the reverse channel H ds The transmitted signal is Y1 = H ds X d1 + U1, and after amplifying the signal Y1 by α, the signal Is sent to the target node.

[0040] When the target node receives the signal X s1 After passing through the reverse channel Hds The signal after transmission After that, make H sd H ds As the equivalent channel Ξ of the feedback process d1 ;

[0041] The target node uses the LMMSE estimation method to estimate the equivalent channel estimation of the two-way feedback process:

[0042]

[0043] In the second stage, the reverse channel is still used to transmit signals. In some embodiments, the target node sends a conventional pilot to the source node. After receiving the conventional pilot, the source node performs channel estimation through LMMSE to obtain the CSI of the reverse channel, including:

[0044] Use the target node to send a conventional pilot training sequence signal

[0045] The source node receives the signal X d2 After passing through the reverse channel H ds The signal after transmission Y2 = H ds X d2 +U2 and then complete the reverse channel H estimation through LMMSE ds Calculation to obtain the reverse channel estimation

[0046] The source node uses the reverse channel estimation Encode the pilot sequence to obtain the feedback transmission signal

[0047] The target node receives the signal X s2 After passing through the first forward channel H sd The signal after transmission After that, make As the equivalent channel of the feedback process;

[0048] The target node uses the LMMSE estimation method to estimate the equivalent channel estimation of the two-way feedback process:

[0049]

[0050] Ξ d2 Further simplified to:

[0051]

[0052] In some embodiments, it further includes:

[0053] The target node uses the equivalent channel estimation in the first stage and the equivalent channel value in the second stage to perform the first forward channel Hsd Estimation of Finally, the estimation of the first forward channel H sd is as follows:

[0054]

[0055] In some examples, in the first stage, during the two-way feedback process, the signals that the eavesdropping node can eavesdrop on Since the eavesdropping node cannot know the specific information of the random pilot X d1 it is impossible to calculate the equivalent channel H sd H ds specific estimated value.

[0056] In the second stage, during the two-way feedback process, the signals that the eavesdropping node can eavesdrop on are The eavesdropping node can use LMMSE estimation to obtain the estimated value Ξ of the equivalent channel However, since the eavesdropping node cannot obtain the e2 value of it is impossible to calculate the forward eavesdropping channel CSI H se .

[0057] Figure 2 Figure shows the comparison of the MSE index trends between the method of this application and the traditional LS algorithm. It can be clearly seen from Figure 2 that as the signal-to-noise ratio increases, the estimated values of the channels for both gradually decrease as a whole. Since the power of the pilot is higher than the power of the interference signal with the increase of the signal-to-noise ratio, the signal can be better detected at the receiving end, which is beneficial to the channel estimation from the target node to the source node, and this is also in line with common sense. At the same time, under the condition of the same signal-to-noise ratio, the mean square error of the algorithm is one order of magnitude smaller than that of the conventional estimation algorithm at 5 dB. As the communication environment quality improves, the gap between the two continuously decreases, but the calculation result of the algorithm is always better than that of the conventional algorithm, which also verifies the effectiveness of the channel security enhancement algorithm.

[0058] A quadratic two-way feedback differential channel estimation method for non-reciprocal channels disclosed in this application aims to optimize the channel estimation performance of legitimate nodes while restricting the channel estimation performance of eavesdropping nodes. Compared with the traditional differential channel estimation scheme with a multi-stage training process, it avoids the source node from separating part of the power for the transmission of artificial noise and uses all the power for the transmission of effective signals, effectively reducing the power consumption of communication devices in practical applications.

[0059] ​The secondary two-way feedback differential channel estimation method of this application enables legitimate nodes to effectively calculate the channel state information of the legitimate channel through a two-stage two-way feedback training process. While eavesdropping nodes cannot obtain any effective estimation values in the first stage because they do not know the content of the random pilot, and although they can obtain effective equivalent channel estimation values in the second stage, they cannot perform further operations due to the lack of equivalent channel state information in the first stage, so they have no way to obtain the forward channel of the eavesdropping nodes. This can effectively prevent eavesdropping nodes from carrying out further information theft work.

[0060] An embodiment of this application also proposes a secondary two-way feedback differential communication system for non-reciprocal channels, including a source node, a target node, and an eavesdropping node. At the source node, n s sub-arrays are configured, at the target node, n d sub-arrays are configured, and at the eavesdropping node, n e sub-arrays are configured. During the process of the source node sending data to the target node, the channel through which the data passes is defined as the first forward channel; during the process of the target node sending data to the source node, the channel through which the data passes is defined as the reverse channel; during the process of the eavesdropping node sending data to the source node, the channel through which the data passes is defined as the second forward channel, where:

[0061] Using the reverse channel to transmit a signal, the target node sends a random pilot to the source node. After receiving the random pilot information, the source node only amplifies the received information and forwards it back to the target node;

[0062] Using the reverse channel to transmit a signal, the target node sends a conventional pilot to the source node. After receiving the conventional pilot, the source node performs channel estimation through LMMSE. After obtaining the CSI of the reverse channel, the source node encodes the received signal using the channel estimation result and feeds it back to the target node through the forward channel.

[0063] An embodiment of this application also proposes a computer-readable storage medium. A computer program is stored on the computer-readable storage medium. When the computer program is executed by a processor, the steps of the secondary two-way feedback differential channel estimation method as described above are implemented.

[0064] It should be noted that in each embodiment of this application, the term "including", "comprising", or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a process, method, article, or device. Without further limitations, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article, or device including that element.

[0065] The serial numbers of the embodiments of the present application above are only for description and do not represent the superiority or inferiority of the embodiments.

[0066] Through the description of the above embodiments, those skilled in the art can clearly understand that the above embodiment methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions for causing a terminal (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present application.

[0067] The embodiments of the present application have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above specific implementation manners. The above specific implementation manners are only illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims. All of these are within the protection scope of the present application.

Claims

1. A quadratic bidirectional feedback differentiated channel estimation method for a non-reciprocal channel is applied to a communication system including a source node, a target node and an eavesdropping node, wherein: Configure at the source node subarrays, target node configuration Subarray and eavesdropping node configuration In the process of the source node sending data to the target node, the channel through which the data passes is defined as the first forward channel; When the target node sends data to the source node, the channel through which the data passes is defined as the reverse channel; When the source node sends data to the destination node, the channel through which the data passes from the source node to the eavesdropping node is defined as the second forward channel H se , the secondary bidirectional feedback differentiated channel estimation method comprises the following steps: The target node transmits a random pilot to the source node by using the reverse channel to transmit the signal. After receiving the random pilot information, the source node only amplifies the received information and forwards it back to the target node. The reverse channel is used to transmit a signal, and the target node sends a conventional pilot to the source node. After receiving the conventional pilot, the source node performs channel estimation through LMMSE, obtains the CSI of the reverse channel, encodes the received signal using the channel estimation result, and feeds it back to the target node through the forward channel; The target node sends a random pilot to the source node. After receiving the random pilot information, the source node only amplifies the received information and forwards it back to the target node, including: Use the target node to send a random pilot training sequence signal ; The source node receives the signal Through the reverse channel The signal after transmission is , the signal enlarge After getting the signal , send it to the target node; The signal is received at the target node Through the reverse channel Signal after transmission After that, As an equivalent channel for the feedback process; The target node estimates the equivalent channel estimate of the bidirectional feedback process using the LMMSE estimation method: The target node sends a conventional pilot to the source node. After receiving the conventional pilot, the source node performs channel estimation through LMMSE to obtain the CSI of the reverse channel, including: Use the target node to send a conventional pilot training sequence signal ; The source node receives the signal Through the reverse channel Signal after transmission The reverse channel is then estimated by LMMSE Calculate and obtain the reverse channel estimate ; The source node uses the reverse channel estimation Encode the pilot sequence to obtain the feedback transmission signal ; The target node receives the signal Through the first forward channel Signal after transmission After that, As an equivalent channel for the feedback process; The target node estimates the equivalent channel estimate of the bidirectional feedback process using the LMMSE estimation method: ； The method further includes: the target node uses the equivalent channel estimation of the first stage and the equivalent channel value of the second stage to perform the first forward channel H sd Estimates , and finally get the first forward channel H sd The estimate is: 。 2. The secondary bidirectional feedback differentiated channel estimation method according to claim 1, characterized in that: Also includes: The target node uses the equivalent channel estimation of the first stage and the equivalent channel value of the second stage to perform the first forward channel Estimates.

3. A secondary bidirectional feedback differentiated communication system for a non-reciprocal channel, characterized in that: Including source node, target node and eavesdropping node, configured at the source node subarrays, target node configuration Subarray and eavesdropping node configuration In the process of the source node sending data to the target node, the channel through which the data passes is defined as the first forward channel; When the target node sends data to the source node, the channel through which the data passes is defined as the reverse channel; When the source node sends data to the destination node, the channel through which the data passes from the source node to the eavesdropping node is defined as the second forward channel H se ,in: The target node transmits a random pilot to the source node by using the reverse channel to transmit the signal. After receiving the random pilot information, the source node only amplifies the received information and forwards it back to the target node. The reverse channel is used to transmit a signal, the target node sends a conventional pilot to the source node, and the source node, after receiving the conventional pilot, performs channel estimation through LMMSE, obtains the CSI of the reverse channel, encodes the received signal using the channel estimation result, and feeds it back to the target node through the forward channel; the target node sends a random pilot to the source node, and the source node, after receiving the random pilot information, only amplifies the received information and forwards it back to the target node, including: Use the target node to send a random pilot training sequence signal ; The source node receives the signal Through the reverse channel The signal after transmission is , the signal enlarge After getting the signal , send it to the target node; The signal is received at the target node Through the reverse channel The signal after transmission; After that, As an equivalent channel for the feedback process; The target node estimates the equivalent channel estimate of the bidirectional feedback process using the LMMSE estimation method: The target node sends a conventional pilot to the source node. After receiving the conventional pilot, the source node performs channel estimation through LMMSE to obtain the CSI of the reverse channel, including: Use the target node to send a conventional pilot training sequence signal ; The source node receives the signal Through the reverse channel Signal after transmission The reverse channel is then estimated by LMMSE Calculate and obtain the reverse channel estimate ; The source node uses the reverse channel estimation Encode the pilot sequence to obtain the feedback transmission signal ; The target node receives the signal Through the first forward channel Signal after transmission After that, As an equivalent channel for the feedback process; The target node estimates the equivalent channel estimate of the bidirectional feedback process using the LMMSE estimation method: ； The method further includes: the target node uses the equivalent channel estimation of the first stage and the equivalent channel value of the second stage to perform the first forward channel H sd Estimates , and finally get the first forward channel H sd The estimate is: 。 4. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the secondary bidirectional feedback differentiated channel estimation method according to claim 1 or 2 are implemented.

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