阅读说明：本技术 多用户抗干扰信道接入系统及动态频谱协同抗干扰方法 (Multi-user anti-interference channel access system and dynamic spectrum cooperative anti-interference method ) 是由 徐煜华 徐逸凡 姚凯凌 李文 刘松仪 栾合禹 于 2019-10-30 设计创作，主要内容包括：本发明公开了一种多用户抗干扰信道接入系统及动态频谱协同抗干扰方法。该系统为：考虑分布式无线网络,该网络内部有多个通信用户,网络外部受到恶意干扰的攻击；网络内处于同一冲突域内的用户可以通过宽带频谱感知判断此时干扰信号,并通过分布式信道决策选择通信信道,以避开恶意干扰,避免同频互扰。方法为：首先通信方观测干扰信号,并将干扰信号作为“协调信号”；然后根据协调信号与对应的信道接入策略表,指导己方用户选频并进行数据传输；传输后,根据是否接收到ACK反馈判断传输是否成功；最后,根据传输情况更新信道接入策略表。本发明模型完备,物理意义清晰,抗干扰能力强,避免了同频互扰,提高了分布式无线网络的信道传输效率。(The invention discloses a multi-user anti-interference channel access system and a dynamic spectrum cooperative anti-interference method. The system is as follows: considering a distributed wireless network, wherein a plurality of communication users are arranged in the network, and the outside of the network is attacked by malicious interference; the users in the same conflict domain in the network can judge the interference signal at the moment through broadband spectrum sensing, and select a communication channel through distributed channel decision, so as to avoid malicious interference and avoid same-frequency mutual interference. The method comprises the following steps: firstly, a communication party observes an interference signal and takes the interference signal as a 'coordination signal'; then, according to the coordination signal and the corresponding channel access strategy table, the own user is guided to select frequency and carry out data transmission; after transmission, judging whether the transmission is successful according to whether ACK feedback is received or not; and finally, updating the channel access policy table according to the transmission condition. The invention has the advantages of complete model, clear physical significance and strong anti-interference capability, avoids same frequency mutual interference and improves the channel transmission efficiency of the distributed wireless network.)

1. A multi-user anti-interference channel access system is characterized by comprising a distributed wireless network, wherein N users, M channels and N channels are shared in the system>M, user set is

2. The multiuser antijam channel access system as claimed in claim 1 wherein the users transmit in a slotted manner, i.e., there is a set of slots

wherein, δ (a)_n(t)) -1 indicates that the user can normally transmit data, δ (a)_n(t)) -0 indicates a data transmission collision; a is_-n(t) is the channel selected by the network other than user n in the time slot t, a_j(t) a channel selected for the t-slot jammer.

3. The multi-user anti-interference channel access system according to claim 1, wherein when the jammer transmits the malicious interference signal, the user in the same collision domain can judge the channel where the interference signal is located by sensing the broadband spectrum, and the channel a selected by the jammer at this time is a channel a selected by the jammer_j(t) is also public information that can be perceived by the user and can be utilizedCoordinating the frequency of the own party;

defining the throughput of user n as:

wherein the content of the first and second substances,

the total system throughput is:

the optimization goals of the network are as follows:

a_opt(t)＝arg max Tr(t) (4)

the optimization target is to find the optimal access strategy of the current time slot full-network user, so that the system throughput is maximum.

4. The multi-user anti-interference channel access system according to claim 1, wherein a game theory is adopted to solve distributed decision optimization, and a multi-agent frequency selection decision is modeled as an anti-interference channel selection game; setting the game model as

5. A dynamic spectrum collaborative anti-interference method based on the multi-user anti-interference channel access system of any one of claims 1 to 4 is characterized by comprising the following steps:

step 1, setting simulation starting-ending time, setting user number and channel number, initializing channel access strategy table of user to all relevant signals

Step 2, circulation: when the user observes the current channel which is maliciously interfered, the state of the related signal is determined

Step 3, all users access to a in the policy table according to the channel_n(C_t) Accessing the selected channel; if a_n(C_t) If the time slot t is 0, the user n selects not to access the channel in the current time slot t, and the step 4 is carried out; such asFruit a_n(C_t) If the time slot t is more than 0, the user n selects to access the corresponding channel in the current time slot t, and the step 5 is carried out;

and step 4, monitoring: in time slot t, if a_n(C_t) If 0, the user does not transmit in the time slot, and selects one channel from the current channels

And step 5, transmission: in time slot t, if a_n(C_t) If > 0, user n is in channel a_n(C_t) If the transmission rate is more than 0, the user determines whether the current transmission is successful according to whether the ACK is received or not and determines a return value R after the transmission_t(ii) a If the transmission is successful, user n maintains a_n(C_t) The corresponding mapping is not changed, when the same correlated signal C appears at the t + k time slot_t+k＝C_tMaintaining the same access strategy; if the transmission fails, the user n has a conflict according to the probability P_deferA is to_n(C_t) Set to 0, the conflicting user will be C in the current interference state_tTo delay transmission to avoid subsequent collisions;

and 6, circulating the steps 2-5 until the maximum iteration times is reached, and finishing the algorithm.

6. The dynamic spectrum cooperative antijam method of the multi-user antijam channel access system of claim 5, characterized in that, the method operates according to the specific MAC layer protocol, thus making the following assumptions:

1) the user and jammer selectable channels are equal;

2) time is divided into equal time slots, each time slot t is used as a transmission unit and comprises the processes of signal observation, channel access, data packet transmission, ACK feedback and learning;

3) the users can synchronize when the channel is idle;

4) each user is equipped with 2 half-duplex antennas, one for data transmission and the other for associated signal perception.

7. The dynamic spectrum cooperative anti-interference method of the multi-user anti-interference channel access system according to claim 6, wherein the method operates according to a specific MAC layer protocol, specifically as follows:

firstly, each user observes the channel where the current interference is located, the channel condition where the interference is located is mapped into related signals, and for each related signal, the user maintains an online updated strategy table which is mapped to an optional channel space from the related signal space;

then, the user accesses the channel according to the respective access strategy table, the data packet transmission is started after the channel is accessed, after the data is transmitted, the transmitter judges whether the ACK replied by the receiver is received or not, and whether the transmission is successful or not is judged according to the existence of the ACK;

and finally, the user updates the access strategy table according to the feedback condition, and accesses the corresponding channel according to the updated channel access strategy table when the interference signal, namely the same related signal, appears next time.

8. The dynamic spectrum collaborative interference rejection method for the multiuser interference-resistant channel access system according to claim 5, 6 or 7, wherein the channel access policy table for all relevant signals by the initialization user in step 1

for each interference signal which possibly appears, randomly mapping the interference signal into an access channel, and if the corresponding time slot t is the interference signal state C_tThen all users areThe current interference signal state C can be sensed through a broadband frequency spectrum_tAnd according to the channel access strategy a in the channel access strategy table of the current time slot_n(C_t) Performing channel access; when the user does not transmit, the user changes to a receiving state and carries out channel interception; because the antenna of the user can receive the transmitting signal of the full frequency band, the handshake between the receiving and the transmitting can be avoided; after each transmission, if the sending end does not receive the ACK feedback from the receiving end, the channel is considered to be unavailable, and when the access strategy is updated, the user n will be a_n(C_t) Setting zero; if the sending end receives the ACK feedback from the receiving end, the sending end keeps the access strategy table unchanged, at the moment, other users which do not transmit randomly select the channel m to monitor, and if the monitoring channel is idle, the access strategy table is set as m.

9. The dynamic spectrum cooperative antijam method of the multiuser antijam channel access system according to claim 8, wherein the determining of the relevant signal state in step 2

in time slot t, if the jammer interferes with channel m and channel m +1, the correlation signal observed by the user is C_tWhen the jammer changes the interference channel to m-1, m +2 in the time slot t +1, the correlation signal observed by the user is C_t{ m-1, m, m +2 }; in the modeling process, the interference mode is not limited, and the number of channels which can be interfered at each time is not limited.

Technical Field

The invention belongs to the technical field of wireless communication anti-interference, and particularly relates to a multi-user anti-interference channel access system and a dynamic spectrum cooperative anti-interference method.

Background

With the rapid development of wireless communication, the number of frequency devices is increasing explosively, and the spectrum resources are gradually in short supply. On one hand, in order to improve the spectrum utilization efficiency, a more effective channel multiple access method needs to be researched; on the other hand, in a military scenario, when malicious interference interferes with a legal signal of a user, communication coordination among users is interrupted due to the existence of the interference signal, so that multi-user frequency coordination is more difficult. How to realize avoiding internal same-frequency mutual interference while resisting external malicious interference threat has important significance in military wireless communication. Under the condition of malicious interference, a reliable centralized controller does not exist usually, information interaction between communication nodes is difficult, and only distributed decision can be usually made, so that the problem of distributed frequency selection of communication equipment is an important problem to be solved urgently in a severe environment.

Aiming at the internal cooperation problem of the frequency-using equipment, some researchers pay attention to the elimination of interference (same frequency mutual interference) among users, model the interference elimination problem by using a game theory, solve the problem by adopting a game learning algorithm, only consider the elimination of the same frequency mutual interference, and do not consider how to resist malicious interference. Aiming at the problem of external countermeasure of Frequency equipment, in a traditional Frequency-Hopping Spread Spectrum (FHSS) method, two communication parties hop according to a fixed Frequency table, and the method belongs to a fixed Frequency Spectrum anti-interference method; in the Direct Sequence Spread Spectrum (DSSS) method, both parties spread the spectrum of a signal at the transmitting end using a high-rate spreading Sequence, and despread the signal at the receiving end using the same spreading code Sequence, restoring the spread spectrum to the original signal. However, when the available channel status changes, it is difficult for the conventional method to achieve reliable communication through the frequency hopping code/spreading code shared in advance.

However, the above studies have the following problems: 1. usually, the "internal cooperation" or the "external countermeasure" of the frequency utilization device is considered unilaterally, but the two are not considered simultaneously, in a practical system, especially in a military environment, the two often exist simultaneously, and the internal and external coupling relation is obvious; 2. the existing method only considers avoiding or resisting malicious interference threat, and does not consider using interference signals to assist own users to carry out spectrum cooperation; 3. the existing method generally considers modeling the interference signal aiming at a specific interference mode or pattern, and in an actual scene, obtaining the information of an interference party is very difficult.

Correlation equalization (r.j. aumann, "Correlated equilibrium as an expression of baysian ratio", economica: Journal of the economic Society, pp.118,1987.) is a very important concept in game theory that can be used to solve the distributed channel decision problem. In implementing the correlation equalization, it is generally assumed that there is a common correlation device coordinating all user actions, which recommends a channel decision to each user according to a probability distribution that achieves correlation equalization when no user can increase its own utility by deviating from the recommended action. The relevant device is similar to a "manager" and thus fairness can be guaranteed. However, it is very difficult to achieve coherent equalization in a distributed wireless network under a malicious interference attack. Firstly, in a distributed wireless network, relevant equipment in the role of a manager is unavailable, and in a severe interference environment, communication and coordination are more difficult to realize at the same time, so that a new way is needed to find the relevant equipment; second, the MAC layer protocol for interference free channel access needs to be redesigned to support the algorithm to achieve both internal coordination and external countermeasure.

Disclosure of Invention

The invention aims to provide a multi-user anti-interference channel access system and a dynamic spectrum cooperative anti-interference method, which have the advantages of complete model, clear physical significance, strong anti-interference capability, capability of avoiding same-frequency mutual interference and improvement on channel transmission efficiency of a distributed wireless network.

The technical solution for realizing the purpose of the invention is as follows: a multi-user anti-interference channel access system comprises a distributed wireless network, wherein N users, M channels and N channels are totally arranged in the system>M, user set is

Set of available channels as

An interference machine is arranged in the network to interfere a user communication channel, and a cluster head node is arranged in each user to manage the whole user cluster; each user has two radio transceivers, one for transmitting signals and one for performing wideband spectrum sensing.

Further, the users transmit in a time-slotted manner, i.e. there is a time slot set

For any time slot

User n selects channel c_mCarry out communication in which

Defining the channel selection strategy of a user n in t time slot as a_n(t) then there is a_n(t)＝c_m(ii) a Considering that a system has a plurality of users, if the plurality of users select the same channel, the same frequency mutual interference is generated, so that any user can not communicate; if the interfering channel interferes with the channel on which the user is communicating, the user is also affectedNormal communication cannot be realized; definition of δ (a)_n(t)) is the channel collision situation of user n on the selected channel, and is specifically defined as follows:

wherein, δ (a)_n(t)) -1 indicates that the user can normally transmit data, δ (a)_n(t)) -0 indicates a data transmission collision; a is_-n(t) is the channel selected by the network other than user n in the time slot t, a_j(t) a channel selected for the t-slot jammer.

Further, when the jammer transmits a malicious jamming signal, the users in the same collision domain can judge the channel where the jamming signal is located through broadband spectrum sensing, and the channel a selected by the jammer at the moment_j(t) is also public information that can be perceived by the user and can be used for frequency coordination of own party;

defining the throughput of user n as:

wherein the content of the first and second substances,

channel bandwidth, P, of an access channel for a user n_nFor the transmission power of user n, d_nFor the distance from the transmitter to the receiver for user n, α is the path fading coefficient,

is the noise power of channel m;

the total system throughput is:

the optimization goals of the network are as follows:

a_opt(t)＝argmaxTr(t) (4)

the optimization target is to find the optimal access strategy of the current time slot full-network user, so that the system throughput is maximum.

Further, a game theory is adopted to solve distributed decision optimization, and a multi-agent frequency selection decision is modeled into an anti-interference channel selection game; setting the game model as

Wherein

In order to be a set of users,as a jammer, A_nA.m. is a set of policies available to a user, a_jSet of available interference channels for jammers, A_j＝A_n,

Namely, the user communication channel set is equal to the interference channel set of the jammer; u. of_nDefining the utility function of a single user as the throughput of the single user in a single time slot for the utility function of the user n, and omitting the time slot t, then u_n(a_n,a_-n,a_j)＝Tr_n(a_n,a_-n,a_j) Wherein a is_n∈A_nA policy is selected for the channel of user n,

channel selection strategies for all users except n, a_j∈A_jIs an interfering channel policy for jammers.

A dynamic spectrum cooperative anti-interference method based on the multi-user anti-interference channel access system comprises the following steps:

step 1, setting simulation starting-ending time, setting user number and channel number, initializing channel access strategy table of user to all relevant signals

Step 2, circulation: when the user observes the current channel which is maliciously interfered, the state of the related signal is determined

Step 3, all users access to a in the policy table according to the channel_n(C_t) Accessing the selected channel; if a_n(C_t) If the time slot t is 0, the user n selects not to access the channel in the current time slot t, and the step 4 is carried out; if a is_n(C_t) If the time slot t is more than 0, the user n selects to access the corresponding channel in the current time slot t, and the step 5 is carried out;

and step 4, monitoring: in time slot t, if a_n(C_t) If 0, the user does not transmit in the time slot, and selects one channel from the current channels

Monitoring is carried out; if the current monitored channel is idle in the current interference state, the user orders an access strategy a at the end of the time slot_n(C_t) M' and the same correlation signal C appears in the following t + k time slot_t+k＝C_tWhen the user n accesses the channel m'; if the channel m' has transmission or malicious interference in the current time slot, the user n keeps the current access strategy a_n(C_t)＝0；

And step 5, transmission: in time slot t, if a_n(C_t) If > 0, user n is in channel a_n(C_t) If the transmission rate is more than 0, the user determines whether the current transmission is successful according to whether the ACK is received or not and determines a return value R after the transmission_t(ii) a If the transmission is successful, user n maintains a_n(C_t) The corresponding mapping is not changed, when the same correlated signal C appears at the t + k time slot_t+k＝C_tMaintaining the same access strategy; if the transmission fails, the user n has a conflict according to the probability P_deferA is to_n(C_t) Set to 0, the conflicting user will be presentInterference state is C_tTo delay transmission to avoid subsequent collisions;

and 6, circulating the steps 2-5 until the maximum iteration times is reached, and finishing the algorithm.

Further, the method works according to a specific MAC layer protocol, so the following assumptions are made:

1) the user and jammer selectable channels are equal;

2) time is divided into equal time slots, each time slot t is used as a transmission unit and comprises the processes of signal observation, channel access, data packet transmission, ACK feedback and learning;

3) the users can synchronize when the channel is idle;

4) each user is equipped with 2 half-duplex antennas, one for data transmission and the other for associated signal perception.

Further, the method works according to a specific MAC layer protocol, specifically as follows:

firstly, each user observes the channel where the current interference is located, the channel condition where the interference is located is mapped into related signals, and for each related signal, the user maintains an online updated strategy table which is mapped to an optional channel space from the related signal space;

then, the user accesses the channel according to the respective access strategy table, the data packet transmission is started after the channel is accessed, after the data is transmitted, the transmitter judges whether the ACK replied by the receiver is received or not, and whether the transmission is successful or not is judged according to the existence of the ACK;

and finally, the user updates the access strategy table according to the feedback condition, and accesses the corresponding channel according to the updated channel access strategy table when the interference signal, namely the same related signal, appears next time.

Further, initializing the channel access policy table of the user for all relevant signals in step 1

The method comprises the following specific steps:

for each interfering signal that may occur, it is randomMapping to an access channel, if corresponding to time slot t, the state of interference signal is C_tAll users can sense the current interference signal state C through the broadband spectrum_tAnd according to the channel access strategy a in the channel access strategy table of the current time slot_n(C_t) Performing channel access; when the user does not transmit, the user changes to a receiving state and carries out channel interception; because the antenna of the user can receive the transmitting signal of the full frequency band, the handshake between the receiving and the transmitting can be avoided; after each transmission, if the sending end does not receive the ACK feedback from the receiving end, the channel is considered to be unavailable, and when the access strategy is updated, the user n will be a_n(C_t) Setting zero; if the sending end receives the ACK feedback from the receiving end, the sending end keeps the access strategy table unchanged, at the moment, other users which do not transmit randomly select the channel m to monitor, and if the monitoring channel is idle, the access strategy table is set as m.

Further, the determining of the relevant signal state as described in step 2

The method comprises the following specific steps:

in time slot t, if the jammer interferes with channel m and channel m +1, the correlation signal observed by the user is C_tWhen the jammer changes the interference channel to m-1, m +2 in the time slot t +1, the correlation signal observed by the user is C_t{ m-1, m, m +2 }; in the modeling process, the interference mode is not limited, and the number of channels which can be interfered at each time is not limited.

Compared with the prior art, the invention has the remarkable advantages that: (1) an anti-interference model of 'internal cooperation and external countermeasure' is adopted, and a corresponding anti-interference algorithm is designed under the model to coordinate internal mutual interference and counteract external malicious interference; (2) the model is complete, the physical significance is clear, the provided dynamic spectrum collaborative anti-interference method realizes the effective solution of the multi-user anti-interference channel access system, and can realize the multi-user collaborative interference channel decision; (3) the large-scale frequency utilization equipment cooperative anti-interference scene can be well depicted.

Drawings

Fig. 1 is a schematic structural diagram of a multi-user interference-free channel access system in the present invention.

Fig. 2 is a schematic diagram of a user initiated access policy in the present invention.

Fig. 3 is a diagram illustrating mapping between an interference channel and a correlation signal according to the present invention.

Fig. 4 is a schematic structural diagram of the interference-free channel access MAC layer protocol based on the correlation equilibrium learning in the present invention.

Fig. 5 is a time-frequency diagram under frequency sweep interference in the embodiment of the present invention.

Fig. 6 is a time-frequency diagram under dynamic frequency sweep interference in the embodiment of the present invention.

FIG. 7 is a time-frequency diagram under random interference in the embodiment of the present invention.

Detailed Description

The invention is described in further detail below with reference to the figures and the embodiments.

The invention discloses a multi-user anti-interference channel access system and a dynamic spectrum collaborative anti-interference method, and aims to solve the problem of distributed anti-interference channel access of multi-frequency equipment. The users in the same conflict domain in the network can judge the interference signal at the moment through broadband spectrum sensing, and select a communication channel through distributed channel decision, so as to avoid malicious interference and avoid same-frequency mutual interference. Specifically, the communication party observes the interference signal and takes the interference signal as a "coordination signal"; according to the coordination signal and the corresponding channel access strategy table, guiding the own user to select frequency and perform data transmission; after transmission, judging whether the transmission is successful according to whether ACK feedback is received or not; and finally, updating the channel access policy table according to the transmission condition.

With reference to fig. 1, a multi-user anti-interference channel access system is characterized in that: considering a distributed wireless network, there are N users, M channels, N in the system>M, user set is

Set of available channels as

An interference machine is arranged in the network to interfere a user communication channel, and a cluster head node is arranged in each user to manage the whole user cluster; each user has two radio transceivers, one for transmitting signals and one for performing wideband spectrum sensing.

Further, the users transmit in a time-slotted manner, i.e. there is a time slot set

For any time slotUser n selects channel c_mCarry out communication in which

Defining the channel selection strategy of a user n in t time slot as a_n(t) then there is a_n(t)＝c_m(ii) a Considering that a system has a plurality of users, if the plurality of users select the same channel, the same frequency mutual interference is generated, so that any user can not communicate; if the interference channel interferes the channel where the user communication is located, the user cannot realize normal communication; definition of δ (a)_n(t)) is the channel collision situation of user n on the selected channel, and is specifically defined as follows:

wherein, δ (a)_n(t)) -1 indicates that the user can normally transmit data, δ (a)_n(t)) -0 indicates a data transmission collision; a is_-n(t) is the channel selected by the network other than user n in the time slot t, a_j(t) a channel selected for the t-slot jammer.

Further, when the jammer transmits a malicious jamming signal, the user in the same collision domain can judge the channel where the jamming signal is located through broadband spectrum sensing, and the channel a selected by the jammer at the moment_j(t) is also public information that can be perceived by the user and can be used for frequency coordination of own party;

defining the throughput of user n as:

wherein the content of the first and second substances,

channel bandwidth, P, of an access channel for a user n_nFor the transmission power of user n, d_nFor the distance from the transmitter to the receiver for user n, α is the path fading coefficient,

is the noise power of channel m;

the total system throughput is:

the optimization goals of the network are as follows:

a_opt(t)＝argmaxTr(t) (4)

the optimization target is to find the optimal access strategy of the current time slot full-network user, so that the system throughput is maximum.

Further, a game theory is adopted to solve distributed decision optimization, and a multi-agent frequency selection decision is modeled into an anti-interference channel selection game; setting the game model as

Wherein

In order to be a set of users,

for jammers, it is set that there is a jammer in the system, A_n＝{0,1,...M is a set of user-available policies, A_jSet of available interference channels for jammers, A_j＝A_n,

Namely, the user communication channel set is equal to the interference channel set of the jammer; u. of_nDefining the utility function of a single user as the throughput of the single user in a single time slot for the utility function of the user n, and omitting the time slot t, then u_n(a_n,a_-n,a_j)＝Tr_n(a_n,a_-n,a_j) Wherein a is_n∈A_nA policy is selected for the channel of user n,

channel selection strategies for all users except n, a_j∈A_jIs an interfering channel policy for jammers.

With reference to fig. 4, a dynamic spectrum cooperative anti-interference method for a multi-user anti-interference channel access system works according to a specific MAC layer protocol, and sets:

1) the user and jammer selectable channels are equal;

2) time is divided into equal time slots, each time slot t is used as a transmission unit and comprises the processes of signal observation, channel access, data packet transmission, ACK feedback and learning;

3) the users can synchronize when the channel is idle;

4) each user is equipped with 2 half-duplex antennas, one for data transmission and the other for associated signal perception.

The dynamic spectrum collaborative anti-interference method of the multi-user anti-interference channel access system works according to a specific MAC layer protocol, and specifically comprises the following steps:

firstly, each user observes the channel where the current interference is located, the channel condition where the interference is located is mapped into related signals, and for each related signal, the user maintains an online updated strategy table which is mapped to an optional channel space from the related signal space; then, the user accesses the channel according to the respective access strategy table, the data packet transmission is started after the channel is accessed, after the data is transmitted, the transmitter judges whether the ACK replied by the receiver is received or not, and whether the transmission is successful or not is judged according to the existence of the ACK; and finally, the user updates the access strategy table according to the feedback condition, and accesses the corresponding channel according to the updated channel access strategy table when the interference signal, namely the same related signal, appears next time.

The invention discloses a dynamic spectrum collaborative anti-interference method of a multi-user anti-interference channel access system, which comprises the following steps:

step 1, setting simulation starting-ending time, setting user number and channel number, initializing channel access strategy table of user to all relevant signals

Further, the channel access policy table for initializing the user to all relevant signalsThe method comprises the following specific steps:

referring to fig. 2, for each interference signal that may occur, the interference signal is randomly mapped to an access channel, and if the corresponding time slot t is, the state of the interference signal is C_tAll users can sense the current interference signal state C through the broadband spectrum_tAnd according to the channel access strategy a in the channel access strategy table of the current time slot_n(C_t) Performing channel access; when the user does not transmit, the user changes to a receiving state and carries out channel interception; because the antenna of the user can receive the transmitting signal of the full frequency band, the handshake between the receiving and the transmitting can be avoided; after each transmission, if the sending end does not receive the ACK feedback from the receiving end, the channel is considered to be unavailable, and when the access strategy is updated, the user n will be a_n(C_t) Setting zero; if the sending end receives the ACK feedback from the receiving end, the sending end keeps the access strategy table unchanged, at the moment, other users which do not transmit randomly select the channel m to monitor, and if the monitoring channel is idle, the access strategy table is set as m.

Step 2, circulation: when the user observes the current channel which is interfered maliciously, the related signal state is determined according to the aforementioned rule

Further, said determining the state of the relevant signal

The method comprises the following specific steps:

in time slot t, if the jammer interferes with channel 2 and channel 3, the user observes a correlation signal of C_tWhen the jammer changes the interfering channel to channels 1,2 and 4 in time slot t +1, {2,3}, the correlation signal observed by the user is C _t1,2, 4. A mapping diagram of the interference channel and the associated signal is shown in fig. 3. In the modeling process, the interference mode is not limited, and the number of channels which can be interfered at each time is not limited.

Step 3, all users access to a in the policy table according to the channel_n(C_t) Accessing the selected channel; if a_n(C_t) If the time slot t is 0, the user n selects not to access the channel in the current time slot t, and the step 4 is carried out; if a is_n(C_t) If the time slot t is more than 0, the user n selects to access the corresponding channel in the current time slot t, and the step 5 is carried out;

and step 4, monitoring: in time slot t, if a_n(C_t) If 0, the user does not transmit in the time slot, and selects one channel from the current channels

Monitoring is carried out; if the current monitored channel is idle in the current interference state, the user orders an access strategy a at the end of the time slot_n(C_t) M' and the same correlation signal C appears in the following t + k time slot_t+k＝C_tWhen the user n accesses the channel m'; if the channel m' has transmission or malicious interference in the current time slot, the user n keeps the current access strategy a_n(C_t)＝0；

And step 5, transmission: in time slot t, if a_n(C_t) If > 0, user n is in channel a_n(C_t) If the transmission rate is more than 0, the user determines whether the current transmission is successful according to whether the ACK is received or not and determines a return value R after the transmission_tChannel collisions, whether interfered or among users, can result in unsuccessful transmissions; if the transmission is successful, user n maintains a_n(C_t) The corresponding mapping is not changed, when the same correlated signal C appears at the t + k time slot_t+k＝C_tMaintaining the same access strategy; if the transmission fails, the user n has a conflict according to the probability P_deferA is to_n(C_t) Set to 0, the conflicting user will be C in the current interference state_tTo delay transmission to avoid possible subsequent collisions.

And 6, circulating the steps 2-5 until the maximum iteration times is reached, and finishing the algorithm.