A high-speed secure communication method dependent on spatial location points

Abstract

This invention provides a high-speed secure communication method relying on spatial location points, belonging to the field of communication technology. The transmitter performs high-dimensional mapping on multiple original signals, and multiplies these multiple high-dimensional signals bit-by-bit with a Walsh code. The sum of these bit-by-bit multiplication results yields a combined high-dimensional signal. Based on the transmission delay between the transmitter and receiver, the combined high-dimensional signal is pre-coded to obtain a pre-coded signal, which is then transmitted to the receiver. The receiver recovers the received pre-coded signal through a matching operation to obtain a recovered combined high-dimensional signal. This recovered signal is then multiplied bit-by-bit with a Walsh code, and the original signal is obtained by summing the results across all dimensions. This invention utilizes multiple Walsh codes to achieve simultaneous transmission of multiple streams of original signals, resulting in higher-speed secure transmission. Receivers at the intended location can communicate normally, while eavesdroppers at other locations cannot receive the signal or only receive erroneous signals.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, specifically relating to a high-speed secure communication method that depends on spatial location points. Background Technology

[0002] In recent years, the concept of physical layer secure communication technology has been proposed both domestically and internationally to address the difficulties in key distribution faced by traditional upper-layer encrypted communication mechanisms, and their unsuitability for large-scale networks with limited resources. Physical layer secure communication technology moves the communication security checkpoint forward to the physical layer and utilizes the channel characteristics of the physical layer to eliminate excessive reliance on long keys. Traditional spatial physical layer secure communication technologies (such as beamforming and directional modulation) can only solve the problem of secure communication in the angular domain. That is, when an eavesdropper is at different angles from a legitimate receiver, the eavesdropper will receive a low-power, incorrectly formatted signal; however, when the eavesdropper is at the same angle (direction) as the legitimate receiver, the eavesdropper may still receive a high-power, correct signal. To extend spatial physical layer secure communication technology from the angular domain to the entire three-dimensional space (including the angular and range domains), the invention patent with publication number CN112104582B, entitled "I / Q Domain Modulation Method, Dual-Domain Modulation Method, and Multiple Access Communication Method," discloses a technology that can achieve secure communication in the range domain. This allows a receiver at a predetermined location to communicate normally, while eavesdroppers at other locations cannot receive signals or only receive erroneous signals. However, this technology achieves range domain security at the cost of a significant reduction in transmission rate. For example, in claim 1, if the generated I / Q domain high-dimensional precoded signal has a dimension of M, its communication rate will become 1 / M of the original. As M increases, this results in a severe loss of communication rate. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a high-speed secure communication method that relies on spatial location points.

[0004] The specific technical solution of this invention is as follows:

[0005] A high-speed secure communication method relying on spatial location points, characterized by comprising the following steps:

[0006] S1: The transmitter transmits M raw signals s respectively. i (t), i = 1, 2, ..., M, are mapped to a high dimension, copied M times, and then shrunk. Times, to obtain the high-dimensional signal s i i = 1, 2, ..., M:

[0007]

[0008] Wherein, the symbol "T" represents transpose; t represents time;

[0009] S2: Generates a length of 2 n Walsh code group H (n) Where n = log₂M, the method of generation is as follows:

[0010] When n=1, the Walsh code group is

[0011] When n > 1, H (n) By H (n-1) get:

[0012]

[0013] Then obtain the Walsh code

[0014]

[0015] in, For Walsh code group H (n) The element in the i-th row and j-th column;

[0016] High-dimensional signal s i With Walsh code Multiplying each digit, we get:

[0017]

[0018] The symbol “⊙” represents digit-by-digit multiplication.

[0019] S3: Summing the signals obtained by multiplying each bit of S2 from the M-path results to obtain the combined high-dimensional signal s. sum :

[0020]

[0021] S4: Based on the transmission delay τ0 between the transmitter and receiver, the combined high-dimensional signal s sum Perform a precoding operation to obtain the precoded signal x(t,τ0):

[0022] x(t,τ0)=A(t,τ0)×s sum

[0023]

[0024] Where A(t,τ0) is the precoding matrix; diag(·) represents a diagonal matrix; Δf is the preset baseband frequency offset value; m i i = 1, 2, ..., M are preset integers;

[0025] S5: The transmitter transmits the precoded signal x(t,τ0) to the receiver, and the receiver recovers the precoded signal upon receiving it.

[0026] S6: The receiver recovers the precoded signal. Perform a matching operation to obtain the merged high-dimensional signal recovery.

[0027]

[0028]

[0029] Where B(t) is the matching matrix;

[0030] S7: Merge high-dimensional signals for recovery With Walsh code By multiplying bit by bit, we obtain the multiplied signal p. i i = 1, 2, ..., M:

[0031]

[0032] Where, p i,j i = 1, 2, ..., M, j = 1, 2, ..., M is the multiplied signal p i The j-th dimension;

[0033] After multiplication, the signal p i Summing each dimension yields the original signal s. i Recovery of (t)

[0034]

[0035] Furthermore, M is a positive integer not less than 2.

[0036] The beneficial effects of this invention are as follows:

[0037] This invention proposes a high-speed secure communication method that relies on spatial location points. It can achieve secure communication in the distance domain, where the receiver at the expected location can communicate normally, while eavesdroppers at other locations cannot receive the signal or can only receive erroneous signals. In addition, by using multiple Walsh codes, it can achieve simultaneous transmission of multiple streams of raw signals and increase the transmission rate by M times, thus achieving higher-speed secure transmission. Attached Figure Description

[0038] Figure 1 This is a flowchart illustrating the high-speed secure communication method based on spatial location points proposed in Embodiment 1 of the present invention.

[0039] Figure 2This is the distance-dependent bit error rate distribution of Embodiment 1 of the present invention when the single-user signal-to-noise ratio is 15dB in a Gaussian white noise channel. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in conjunction with the following specific embodiments and with reference to the accompanying drawings.

[0041] Example 1

[0042] This embodiment proposes a high-speed secure communication method that relies on spatial location points, the process of which is as follows: Figure 1 As shown, this is implemented based on a communication system consisting of a transmitter and a receiver. The transmitter includes a high-dimensional mapping module, a first Walsh code multiplication module, a first summation module, and a position-dependent precoding operation module. The receiver includes a matching operation module, a second Walsh code multiplication module, and a second summation module. The transmitter transmits M=16 channels of original signals s. i (t), i = 1, 2, ..., 16 are transmitted to the receiver. To prevent these 16 original signals from being intercepted by eavesdroppers who are not located at the receiver, this embodiment needs to perform the following steps in sequence:

[0043] S1: In the high-dimensional mapping module, the transmitter processes the 16 original signals s respectively. i (t), i = 1, 2, ..., 16, are subjected to high-dimensional mapping, copied 16 times, and then shrunk. Times, to obtain the high-dimensional signal s i i = 1, 2, ..., 16:

[0044]

[0045] Wherein, the symbol "T" represents transpose; t represents time;

[0046] S2: In the first Walsh code multiplication module, a code of length 2 is generated. n Walsh code group H (n) Where n = log216 = 4, the method of generation is as follows:

[0047] When n=1, the Walsh code group is

[0048] When n > 1, H (n) By H (n-1) get:

[0049]

[0050] Then obtain the Walsh code

[0051]

[0052] in, For Walsh code group H (n) The element in the i-th row and j-th column;

[0053] High-dimensional signal s i With Walsh code Multiplying each digit, we get:

[0054]

[0055] The symbol “⊙” represents digit-by-digit multiplication.

[0056] S3: In the first summation module, the signals obtained by multiplying the 16 channels of S2 bit by bit are summed to obtain the merged high-dimensional signal s. sum :

[0057]

[0058] S4: Based on the transmission delay τ0 between the transmitter's position-dependent precoding operation module and the receiver's matching operation module, the position-dependent precoding operation module performs a combined high-dimensional signal s... sum Perform a precoding operation to obtain the precoded signal x(t,τ0):

[0059] x(t,τ0)=A(t,τ0)×s sum

[0060]

[0061] Where A(t,τ0) is the precoding matrix; diag(·) represents a diagonal matrix; Δf is a preset baseband frequency offset value, which is taken as 1MHz in this embodiment; m i i = 1, 2, ..., 16 are preset integers;

[0062] S5: The transmitter transmits the precoded signal x(t,τ0) to the receiver, and the receiver recovers the precoded signal upon receiving it.

[0063] S6: The receiver's matching operation module recovers the precoded signal. Perform a matching operation to obtain the merged high-dimensional signal recovery.

[0064]

[0065]

[0066] Where B(t) is the matching matrix;

[0067] S7: In the second module that multiplies with the Walsh code, the merged high-dimensional signal is recovered. With Walsh code By multiplying bit by bit, we obtain the multiplied signal p. i i = 1, 2, ..., 16:

[0068]

[0069] Where, p i,j i = 1, 2, ..., 16, j = 1, 2, ..., 16 are the signals p after multiplication. i The j-th dimension;

[0070] The second summation module processes the multiplied signal p i Summing each dimension yields the original signal s. i Recovery of (t)

[0071]

[0072] Figure 2 This embodiment presents the distance-dependent bit error rate distribution of the high-speed secure communication method in a Gaussian white noise channel with a single-user signal-to-noise ratio of 15 dB, where the transmission delay τ0 = 5 × 10⁻⁶. -7 If system processing delay is ignored, then at the corresponding receiver location of 150m, the bit error rate is minimized only at the receiver location, approaching 0, indicating that a correct signal has been received. At other locations, erroneous signals are received. Simultaneously, using the high-speed secure communication method proposed in this embodiment, 16 channels of raw signals can be transmitted in parallel, significantly improving the transmission rate.

Claims

1. A high-speed secure communication method relying on spatial location points, characterized in that, Includes the following steps: S1: The transmitter transmits M raw signals s respectively. i (t), i = 1, 2, ..., M are mapped to a higher dimension to obtain a higher dimension signal s. i i = 1, 2, ..., M: Wherein, the symbol "T" represents transpose; t represents time; S2: Generates a length of 2 n Walsh code group H (n) Where n = log₂M, the method of generation is as follows: When n=1, the Walsh code group is When n > 1 Then obtain the Walsh code in, For Walsh code group H (n) The element in the i-th row and j-th column; High-dimensional signal s i With Walsh code Multiplying each digit, we get: The symbol "⊙" represents digit-by-digit multiplication. S3: Calculate the merged high-dimensional signal s sum : S4: Based on the transmission delay τ0 between the transmitter and receiver, the combined high-dimensional signal s sum Perform a precoding operation to obtain the precoded signal x(t,τ0): x(t,τ0)=A(t,τ0)×s sum Where A(t,τ0) is the precoding matrix; diag(·) represents a diagonal matrix; Δf is the preset baseband frequency offset value; m i i = 1, 2, ..., M are preset integers; S5: The transmitter transmits the precoded signal x(t,τ0) to the receiver, and the receiver recovers the precoded signal upon receiving it. S6: The receiver recovers the precoded signal. Perform a matching operation to obtain the merged high-dimensional signal recovery. Where B(t) is the matching matrix; S7: Merge high-dimensional signals for recovery With Walsh code By multiplying bit by bit, we obtain the multiplied signal p. i i = 1, 2, ..., M: Where, p i,j i = 1, 2, ..., M, j = 1, 2, ..., M is the multiplied signal p i The j-th dimension; This leads to the original signal s. i Recovery of (t) 2. The high-speed secure communication method dependent on spatial location points according to claim 1, characterized in that, M is a positive integer not less than 2.

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