Cooperative cognitive covert communication method based on maximum rate mechanism

Abstract

The present invention discloses a cooperative cognitive covert communication method based on a maximum rate mechanism. In the first vT period, a primary transmitter PT transmits information to a secondary transmitter ST; in the remaining (1‑v)T period, a secondary receiver SR selects the first secondary transmitter ST i , Secondary transmitter ST j , then, the first secondary transmitter ST i The main transmitter PT transmits a signal to the secondary transmitter ST and performs covert communication and assist communication respectively; the main transmitter PT transmits a signal to the first secondary transmitter ST i Transmitting information, the first secondary transmitter ST i The primary transmitter PT transmits information to the secondary transmitter ST according to the amplify-and-forward (AF) protocol. j To monitor the transmission, the second secondary transmitter ST j The secondary receiver SR performs covert transmission; the remaining (K-2) secondary transmitters ST remain silent. The present invention utilizes the uncertainty of the wireless channel and the noise at the receiving end to realize the covert communication of the secondary network, and has good concealment performance, which can ensure the covert communication quality of the secondary network.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to a collaborative cognitive covert communication method based on a maximum rate mechanism. Background Art

[0002] In order to solve the problem of scarce spectrum resources, cognitive radio (CR) technology came into being. It can realize the reuse and sharing of spectrum resources by adapting to changes in the wireless environment, thereby greatly improving spectrum utilization and ensuring communication quality.

[0003] Due to the openness and broadcast characteristics of wireless channels, CR networks are subject to serious threats to security transmission, such as interference and eavesdropping. As we all know, traditional encryption technology has been widely used, but its complex key system has poor universality and will bring excessive communication overhead to the transmission link. At the same time, physical layer security (PLS) technology improves the channel quality of legitimate users by utilizing the dynamic and unique nature of wireless channels, thereby achieving the purpose of secure transmission. However, both encryption technology and PLS technology can only protect wirelessly transmitted information and cannot provide effective protection for communication behavior. From the perspective of information theory, the academic community has proposed a low-detection, low-interception communication method, namely, covert communication technology, which aims to protect the communication behavior itself and can be considered as a more advanced secure transmission technology with broad application prospects. For example, in secret military operations, military confrontations, and when transmitting private information such as personal medical and bank cards, the sender hopes to transmit without being detected by eavesdroppers. This wireless communication technology aimed at protecting communication behavior has gradually come into people's view, and the academic research on covert communication technology has become increasingly mature. However, there is currently a lack of research on covert communication in CR networks, especially research on covert communication in CR networks based on relays. However, with the rapid development of communication technology, CR networks, relay networks, etc. will inevitably be widely used in future communication systems. Future communication networks will be characterized by high density and multi-distribution, and covert communication is bound to become an indispensable key technology. Summary of the invention

[0004] In view of this, the main purpose of the present invention is to provide a collaborative cognitive covert communication method based on a maximum rate mechanism.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] An embodiment of the present invention provides a collaborative cognitive covert communication method based on a maximum rate mechanism, the method comprising:

[0007] In the first vT period, the primary transmitter PT transmits information to the secondary transmitter ST;

[0008] In the remaining (1-v)T period, the secondary receiver SR selects the first secondary transmitter ST i , Secondary transmitter ST j , then, the first secondary transmitter ST i It carries out covert communication and assisting communication with the secondary transmitter ST respectively;

[0009] The primary transmitter PT transmits to the first secondary transmitter ST i Transmitting information, the first secondary transmitter ST i Transmitting information to a primary receiver PR according to an amplify-and-forward (AF) protocol;

[0010] At the same time, the primary transmitter PT sends a signal to the secondary transmitter ST j To monitor the transmission, the second secondary transmitter ST j Covert transmission with secondary receiver SR;

[0011] The remaining (K-2) secondary transmitters ST remain silent.

[0012] In the above scheme, the main transmitter PT transmits a signal to the first secondary transmitter ST i Transmission information, specifically: when the main transmitter PT sends, the first secondary transmitter ST i The received signal is

[0013] Wherein, k = 1, 2, 3, L; n and i = 1; L and l represent the kth communication time slot and the ith ST respectively; represents the channel gain from PT to the i-th ST; Indicates ST i The receiving noise at and P PT Represent the PT signal and its transmission power respectively.

[0014] In the above scheme, the secondary receiver SR selects the first secondary transmitter ST i , Secondary transmitter ST j Specifically, the secondary receiver SR selects a pair of secondary transmitters that maximize the concealed user communication rate according to the maximum rate mechanism to obtain the maximum concealed rate of the network, wherein the pair of secondary transmitters includes a first secondary transmitter ST i , Secondary transmitter ST j .

[0015] In the above scheme, the first secondary transmitter ST i The first secondary transmitter ST transmits information to the primary receiver PR according to the amplify-and-forward (AF) protocol, specifically: iThe received signal After AF amplification, the main user signal is sent to the main receiver PR Expressed as in, Indicates the first secondary transmitter ST i The magnification factor.

[0016] In the above scheme, the main transmitter PT transmits the signal to the second secondary transmitter ST j To monitor the transmission, specifically: the signal received at the main transmitter PT is expressed as

[0017] in, and Respectively represent The known and unknown parts of PT represents the receiving noise at the PT; Indicates ST j No covert communications were conducted. Indicates ST j Covert communications were carried out.

[0018] In the above scheme, the second secondary transmitter ST j The concealed transmission is performed with the secondary receiver SR, specifically: the concealed signal received by the secondary receiver SR is expressed as in, and Respectively represent ST i and ST j to the SR channel gain, and They are ST i and ST j The transmission power, n SR (k) is the received noise at SR.

[0019] In the above scheme, the method also includes the main transmitter PT determining whether the main receiver PT performs covert communication.

[0020] In the above scheme, the main transmitter PT determines whether the main receiver PT performs covert communication, specifically: the main transmitter PT determines whether the main receiver PT sends covert information according to a preset power threshold τ, which is expressed as Where E represents the signal power received by the PT, D 1 and D 0 They represent that PT assumes that ST performs covert communication and does not perform covert communication according to the threshold.

[0021] Compared with the prior art, the present invention utilizes the characteristics of the uncertainty of the wireless channel and the receiver noise to achieve covert communication in the secondary network, and has good covert performance, which can ensure the quality of covert communication in the secondary network. Description of the Drawings

[0022] The drawings described herein are used to disclose a further understanding of the present invention, and constitute a part of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0023] Figure 1 It is a flowchart of a cooperative cognitive covert communication method based on the maximum rate mechanism provided by an embodiment of the present invention;

[0024] Figure 2 It is the error detection probability monitored by the primary transmitter in the present invention;

[0025] Figure 3 It is the covert rate under different covert constraints in the present invention. Detailed Embodiments

[0026] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] It should be noted that in this article, the term "including", "comprising" or any other variant thereof is intended to cover a non-exclusive inclusion, so that a process, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, article or device including that element.

[0028] An embodiment of the present invention provides a cooperative cognitive covert communication method based on the maximum rate mechanism, as Figure 1 shown, the method includes:

[0029] Step 101: In the first vT time period, the primary transmitter PT transmits information to the secondary transmitter ST;

[0030] Specifically, T is the length of each communication time slot.

[0031] v is the communication time slot ratio, and its value is 0 < v < 1; within a communication time slot T, the first vT is the communication time period between the primary transmitter PT and the secondary receiver.

[0032] Step 102: In the remaining (1-v)T period, the secondary receiver SR selects the first secondary transmitter ST i , Secondary transmitter ST j , then, ST i Conduct covert communications and assist communications with ST respectively;

[0033] Specifically, within (1-v)T time, ST i With PR, ST j Communicates with SR simultaneously.

[0034] The secondary receiver SR selects a pair of secondary transmitters that maximize the concealed user communication rate according to the maximum rate mechanism, thereby obtaining the maximum concealed rate of the network, wherein the pair of secondary transmitters includes a first secondary transmitter ST i , Secondary transmitter ST j .

[0035] Step 103: The primary transmitter PT sends a signal to the first secondary transmitter ST i Transmitting information, the first secondary transmitter ST i Transmitting information to a primary receiver PR according to an amplify-and-forward (AF) protocol;

[0036] Specifically, when the primary transmitter PT transmits, the first secondary transmitter ST i The received signal is Wherein, k = 1, 2, 3, L; n and i = 1; L and l represent the kth communication time slot and the ith ST respectively; represents the channel gain from PT to the i-th ST; Indicates ST i The receiving noise at and P PT Represent the PT signal and its transmission power respectively.

[0037] The first secondary transmitter ST i The received signal After AF amplification, the main user signal is sent to the main receiver PR Expressed as in, Indicates the first secondary transmitter ST i The magnification factor.

[0038] Step 104: At the same time, the primary transmitter PT transmits the signal to the secondary transmitter ST. j To monitor the transmission, the second secondary transmitter ST j Covert transmission with secondary receiver SR;

[0039] Specifically, in order to avoid affecting the communication quality of the primary network, the primary transmitter PT will also act as a listener to eavesdrop on illegal communications to avoid occupying its spectrum resources. The signal received at the primary transmitter PT is expressed as in,

[0040] and Respectively represent The known and unknown parts of the channel are expressed as Indicates; n PT represents the receiving noise at PT, which is uncertain and measured by parameter θ; Indicates ST j No covert communications were conducted. Indicates ST j Covert communications were carried out.

[0041] The concealed signal received by the secondary receiver SR is expressed as in, and Respectively represent ST i and ST j to the SR channel gain, and They are ST i and ST j The transmission power, n SR (k) is the received noise at SR.

[0042] Step 105: The remaining (K-2) secondary transmitters ST remain silent.

[0043] Furthermore, the method also includes the primary transmitter PT determining whether the primary receiver PT performs covert communication.

[0044] Specifically, the primary transmitter PT determines whether the primary receiver PT sends concealed information according to a preset power threshold τ, which is expressed as Where E represents the signal power received by the PT, D 1 and D 0 They represent that PT assumes that ST performs covert communication and does not perform covert communication according to the threshold.

[0045] The effect of the present invention can be further illustrated by simulation:

[0046] 1. Simulation conditions:

[0047] Considering one pair of primary users and one hidden receiver, the number of relays K = 10, the communication time slot ratio ν = 0.4, the transmission path loss index is 1, and the other simulation parameters are described in the specific simulation diagram.

[0048] 2. Simulation content:

[0049] Figure 1 It is shown that the probability of detection error varies with the channel uncertainty parameter From the changing trend of , we can find that the average detection error probability of PT is related to the channel uncertainty. The monotonically increasing function of the noise uncertainty θ increases from 0dBm to 2dBm and finally to 4dBm, the probability of PT false detection increases significantly. Figure 2 It can also be seen that as the noise uncertainty and channel uncertainty increase, the probability of false detection of PT increases accordingly. In other words, ST can achieve better concealment performance.

[0050] Figure 2 The variation of the achievable concealment rate with noise uncertainty under different concealment constraints is shown. First, the channel uncertainty parameter is fixed. From the figure, we can see that as the noise uncertainty θ increases, the concealment rate that ST can achieve increases significantly. When the concealment constraint ∈ is relaxed from 0.01 to 0.1, the concealment rate of ST is significantly improved.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention.

Claims

1. A collaborative cognitive covert communication method based on a maximum rate mechanism, characterized in that: The method includes: In the first vT period, the primary transmitter PT transmits information to the secondary transmitter ST; T is the length of each communication time slot, and v is the communication time slot ratio; In the remaining (1-v)T period, the secondary receiver SR selects the first secondary transmitter ST i , Secondary transmitter ST j , then, the first secondary transmitter ST i , Secondary transmitter ST j Conduct covert communication and assist communication with the secondary receiver SR respectively; After (1-v)T time, ST i With the main receiver PR, ST j Communicate with SR simultaneously; The secondary receiver SR selects a pair of secondary transmitters that maximize the concealed user communication rate according to the maximum rate mechanism, thereby obtaining the maximum concealed rate of the network, wherein the pair of secondary transmitters includes a first secondary transmitter ST i , Secondary transmitter ST j ; The primary transmitter PT transmits to the first secondary transmitter ST i Transmitting information, the first secondary transmitter ST i Transmitting information to a primary receiver PR according to an amplify-and-forward (AF) protocol; When the primary transmitter PT transmits, the first secondary transmitter ST i The received signal is Wherein, k = 1, 2, 3, L; n and i = 1; L and l represent the kth communication time slot and the ith ST respectively; represents the channel gain from PT to the i-th ST; Indicates ST i The receiving noise at and P PT Respectively represent the signal of PT and its transmission power; The first secondary transmitter ST i The received signal After AF amplification, the main user signal is sent to the main receiver PR Expressed as in, Indicates the first secondary transmitter ST i The magnification factor of At the same time, the primary transmitter PT sends a signal to the secondary transmitter ST j To monitor the transmission, the second secondary transmitter ST j Covert transmission with secondary receiver SR; Specifically, in order to avoid affecting the communication quality of the primary network, the primary transmitter PT will also act as a listener to eavesdrop on illegal communications. The signal received at the primary transmitter PT is expressed as in, and Respectively represent The known and unknown parts of the channel are expressed as Indicates; n PT represents the receiving noise at PT, which is uncertain and measured by parameter θ; Indicates ST j No covert communications were conducted. Indicates ST j Covert communications were conducted; The concealed signal received by the secondary receiver SR is expressed as in, and Respectively represent ST i and ST j to SR channel gain, and They are ST i and ST j The transmission power, n SR (k) is the received noise at SR; The remaining (K-2) secondary transmitters ST remain silent; The primary transmitter PT determines whether the primary receiver PT performs covert communication; Specifically, the primary transmitter PT determines whether the primary receiver PT sends concealed information according to a preset power threshold τ, which is expressed as Where E represents the signal power received by the PT, D1 and D0 represent the PT assuming that the ST performs covert communication and does not perform covert communication according to the threshold, respectively; The remaining (K-2) secondary transmitters ST remain silent.

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