CN103220094B - Cognition network is carried out and passes and the joint transmission method cooperated - Google Patents

Abstract

The present invention discloses a concurrent transmission and cooperative joint transmission method applied to a cognitive network, which mainly solves the problem of the throughput obtained by the secondary user when the channel condition of the primary user is good for the transmission strategy designed based on the automatic repeat request protocol ARQ Small, and there is no compensation for the throughput loss of the primary user. The main steps are: 1. The secondary user sets the transmission power to ensure that the outage probability of the primary user meets the outage threshold; 2. The secondary user listens to the feedback information of the primary user and judges whether the current time slot is the first transmission time slot or a re-transmission time slot. 3. In the first transmission time slot, the secondary user and the primary user transmit concurrently to obtain throughput; 4. In the retransmission time slot, the secondary user relays to the primary user to compensate for the interference caused by the concurrent transmission to the primary user . The invention enables the primary user to improve the throughput of the secondary user on the premise of obtaining the minimum throughput loss, and has certain compensation for the throughput loss of the primary user, which can be used to improve the transmission efficiency of the cognitive network.

Description

Joint Transmission Method for Parallel Transmission and Collaboration in Cognitive Networks

technical field

The invention belongs to the technical field of wireless communication, relates to a joint transmission method of a cognitive network, and can be used in a cognitive radio network.

Background technique

Cognitive radio networks allow secondary users to use the spectrum resources of primary users for opportunistic transmission on the premise of ensuring the quality of service (QoS) of primary users. In the primary user system based on the automatic repeat request protocol ARQ, the secondary user obtains the current transmission status of the primary user by listening to the data transmission information of the primary user and feedback information such as ACK or NAK. Under the condition that the interference is less than a certain threshold value, opportunistic access is performed. Most of the existing literatures generally use the following transmission method when studying the access mechanism of the secondary user: when the primary user transmits for the first time, the secondary user listens to the transmission of the primary user and tries to decode the data packet of the primary user; When the primary user fails to transmit data for the first time and needs to retransmit, if the secondary user can decode the data packet of the primary user, then in the retransmission time slot of the primary user, the secondary user transmits its own data packet at the same time, and uses interference to eliminate Technology improves the transmission success rate of secondary users.

In this method, the secondary user uses the retransmission time slot of the primary user to access the channel. Only when the primary user makes an error in the first transmission and needs to retransmit, the secondary user has the opportunity to access the channel to achieve parallel transmission with the primary user. In this method, only when the channel condition of the primary user is poor, the secondary user can obtain more access opportunities; when the channel condition of the primary user is good, the probability of retransmission of the primary user is very low, so that the secondary user can obtain Transmission opportunities will be few and far between. Moreover, in this method, the secondary user causes a certain loss to the throughput of the primary user without any compensation.

Contents of the invention

The purpose of the present invention is to address the shortcomings of the above-mentioned prior art, and propose a joint transmission method for concurrent transmission and cooperation in a cognitive network, so as to improve the throughput of the secondary user and compensate for the throughput loss caused by the primary user.

Technical scheme of the present invention is realized like this:

one. Terminology Explanation:

PU: Primary User, primary user,

PT: Primary Transmitter, the transmitter of the main user,

PR: Primary Receiver, the receiver of the main user,

SU: Secondary User, secondary user,

ST: Secondary Transmitter, the transmitter of the secondary user,

SR: Secondary Receiver, the receiver of the secondary user,

ARQ: Automatic Repeat-reQuest, automatic request retransmission,

QoS: Quality of Service, quality of service,

ACK: ACKnowledgment, confirmation response,

NAK: Non-ACKnowledgement, negative response,

two. Technical ideas

In the first transmission time slot of the primary user data packet, the throughput of the secondary user is obtained through concurrent transmission of the secondary user and the primary user; in the retransmission time slot of the primary user data packet, the secondary user is used as the primary user relay, Make up for the throughput loss caused to the primary user during parallel transmission.

three. The transmission method of the present invention comprises the following steps:

(1) The secondary user sets its transmit power according to the statistical channel information of the primary user, so that when the secondary user and the primary user transmit concurrently, the outage probability of the primary user is guaranteed to meet the outage threshold O _PU ;

(2) The secondary user listens to the acknowledgment or negative response feedback information of the primary user receiver PR, and judges whether the current time slot is the first transmission time slot or the retransmission time slot of the data packet according to the feedback information: if the previous time slot If the feedback information is an acknowledgment, then judge that the current time slot is the first transmission time slot, and perform step (3); if the feedback information of the last time slot is a negative response, then judge that the current time slot is a retransmission time slot, and perform step (4) );

(3) The receiver of the secondary user uses the instantaneous channel information to calculate the SINR _i of the current secondary user:

${\mathrm{<span\; class="notranslate">\; SINR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}^{\mathrm{<span\; class="notranslate">\; max</span>}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; SR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; PT</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; SR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; m</span>}$

where P _P and The transmit power of the primary user and the secondary user, respectively, m is the number of secondary users, N ₀ is the background noise power, PT is the transmitter of the primary user, ST _i and SR _i represent the transmission of the ith secondary user tors and receivers, is the instantaneous channel power gain of the i-th secondary user SU _i , Instantaneous channel power gain from the primary user's transmitter PT to the ith secondary user receiver SR _i ;

Compare the SINR _i with the demodulation threshold γ _S of the secondary user data packet, if SINR _i ≥ γ _S , the concurrent transmission condition is met, put the secondary user SU that meets the concurrent transmission condition into the set D, and put the current The concurrent transmission secondary user of the time slot is denoted as SU ^* ;

If D is an empty set, all secondary users SU remain silent, listen to and try to decode the data packets of the primary user PU; if |D|=1, that is, there is only one secondary user SU in D, then the secondary user SU SU performs concurrent transmission with the primary user PU in the current time slot, and all other secondary users SU remain silent, listen to and try to decode the data packets of the primary user PU; if |D|>1, that is, there are multiple secondary users in D SU, select and transmit the secondary user SU ^* according to the following formula:

${\mathrm{<span\; class="notranslate">\; SU</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>\underset{{\mathrm{<span\; class="notranslate">\; SU</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; min</span>}}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; access</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; relay</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ,</span>$

Among them, |D| is the number of elements in the set D, and They are respectively used to record the concurrent transmission times and relay times of the i-th secondary user SU _i up to the current time slot, and SU ^* indicates the concurrent transmission secondary user of the current time slot;

In the current time slot, the secondary user SU ^* is concurrently transmitted with the primary user PU to obtain its own throughput;

The transmitter ST _i of the secondary user not selected as the concurrent secondary user SU ^* uses the instantaneous channel information to calculate the signal-to-interference-noise ratio :

where ST ^* is the transmitter of the concurrent secondary user SU ^* , represents the empty set, is the transmit power of the secondary user SU ^* , The instantaneous channel power gain from the primary user transmitter PT to the ith secondary user transmitter ST _i , is the instantaneous channel power gain from the secondary user's transmitter ST ^* to the i-th secondary user's transmitter ST _i ;

Will Compared with the demodulation threshold γ _P of the main user data packet, if It indicates that ST _i can successfully decode the data packet of the primary user;

Return to step (2), listen to the feedback information of the primary user receiver PR for all remaining time slot secondary users, and perform corresponding operations according to the feedback information;

(4) Decode the ST _i of the primary user data packet in the first transmission time slot, and use the instantaneous channel information to calculate the SNR of the relay channel

${\mathrm{<span\; class="notranslate">\; SNR</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; PR</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; PR</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; ,</span>$

where P _max is the maximum physical power limit of ST _i , PR is the receiver of the primary user, is the instantaneous channel power gain from the i-th secondary user's transmitter ST _i to the primary user's receiver PR;

Will Compared with the demodulation threshold γ _P of the main user data packet, if It indicates that ST _i satisfies the relay condition, put the ST _i satisfying the relay condition into set C, and denote the relay node of the current time slot as ST ^R ;

If C is an empty set, all SUs remain silent in the retransmission time slot, and PT retransmits the data packet; if |C|=1, the transmitter ST of the secondary user entering the set C acts as the relay node ST of the primary user ^R , the primary user retransmits the data packet, and the primary user and other secondary users remain silent in the current time slot; if |C|>1, that is, there are multiple STs in the set C that meet the relay condition, use the following formula to determine the primary User's relay node ST ^R :

${\mathrm{<span\; class="notranslate">\; ST</span>}}^{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\underset{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; C</span>}}{\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; min</span>}}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; relay</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; access</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>$

Among them, |C| is the number of elements in the set C,

In the current time slot, ST ^R acts as the relay node of the primary user, and transmits the data packets lost by the primary user in the first transmission time slot to make up for the loss caused by the secondary user to the primary user during the concurrent transmission. silent;

Returning to step (2), the secondary user listens to the feedback information of the primary user receiver PR for all remaining time slots, and performs corresponding operations according to the feedback information.

The present invention has the following advantages:

1. The present invention adopts a joint transmission method of concurrent transmission and cooperation, so that the throughput obtained by the secondary user increases gradually with the increase of the channel gain of the primary user.

2. In the present invention, the secondary user uses the statistical channel information of the primary user to set its transmission power to meet the interruption threshold of the primary user, so that the secondary user can ensure the QoS of the primary user when transmitting concurrently with the primary user need.

3. The present invention utilizes the mutual cooperation between primary and secondary users and between different secondary users. In the retransmission time slot of the primary user, the secondary user makes up for the retransmission time slot of the primary user by relaying the primary user to a certain extent. The loss caused by the throughput of the primary user, and the primary user achieves the purpose of saving power; by using the instantaneous channel information, the secondary users have the opportunity to obtain their own throughput.

4. In the present invention, when multiple secondary users meet the conditions for concurrent transmission, the secondary user with the most relay times for the primary user is preferentially selected as the secondary user for concurrent transmission. When multiple secondary users meet the conditions for relaying, The secondary users with the most concurrent transmission times are preferentially selected as relay nodes, reflecting the fairness among different secondary users.

Description of drawings

Fig. 1 is a cognitive network scene diagram used in the present invention;

Fig. 2 is a flow chart of the joint transmission method of concurrent transmission and cooperation of the present invention;

Fig. 3 is a simulation result diagram of the present invention.

detailed description

With reference to Fig. 1, comprise a primary user and two secondary users in the emulation scene of the present invention, get m=2 promptly, primary user comprises a primary user transmitter PT and a primary user receiver PR, each secondary user comprises A secondary user transmitter ST and a secondary user receiver SR, where the i-th secondary user's transmitter and receiver are denoted as ST _i and SR _i respectively, the link length of the primary user is d _p , each The link length of the secondary user is d _s ; the primary user uses the stop-equation-ARQ protocol for transmission, and there is no limit to the number of retransmissions. The secondary user performs concurrent transmission and cooperative joint transmission by listening to the feedback information from the primary user receiver. transfer method.

Referring to Fig. 2, the concurrent transmission and cooperative joint transmission method of the present invention includes the following steps:

Step 1: The secondary user sets its own transmission power according to the statistical channel information of the primary user, so that when the secondary user transmits concurrently with the primary user, the outage probability of the primary user is guaranteed to meet the outage threshold value O _PU ;

1a) The secondary user continuously listens to N time slots, where N is a positive integer, and counts the feedback information of the primary user receiver. According to the feedback information of the primary user receiver, the transmission power of the primary user, the interruption threshold and the rate requirement, Estimate |h _PT,PR | ² and where |h _PT,PR | ² is the average channel power gain from the primary user's transmitter PT to the primary user's receiver PR, is the average channel power gain from the i-th secondary user's transmitter ST _i to the primary user's receiver PR;

1b) The secondary user SU utilizes the estimated | _hPT,PR | ² and For the transmit power P _P of the primary user PU, the interruption threshold value O _PU and the rate requirement, the maximum allowable transmit power when concurrently transmitting with the primary user is calculated by the following probability expression

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; PT</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; PR</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; PR</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; PU</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span>$

Among them, P _P is the constant transmission power of the main user, O _PU is the interruption threshold value of the main user, N ₀ is the background noise power, γ _P is the demodulation threshold value of the main user data packet, is the maximum allowable transmission power of the i-th secondary user's transmitter ST _i when concurrently transmitting with the primary user PU;

In the above probability expression is the unknown, P _P , O _PU , N ₀ , γ _P , |h _PT,PR | ² and are known quantities; when the channel model is given, it can be obtained exact expression.

In this embodiment, the channel obeys the Rayleigh block fading model. Substituting the channel model into the above probability expression, the secondary user SU obtains

${\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; PT</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; PR</span>}}^{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}}{{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; PR</span>}}^{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; PT</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; PR</span>}}^{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; PU</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span>$

Among them, d _PT,PR represents the distance from the transmitter PT of the primary user to the receiver PR of the primary user, is the distance from the transmitter ST _i of the i-th secondary user to the receiver PR of the primary user, and α represents the path loss index;

1c) Combining with the maximum physical power limit P _max of the secondary user SU, each secondary user SU determines the final transmission power when it transmits concurrently with the primary user PU:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}^{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; ,</span>& {\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; \&Greater\; Equal;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; ,</span>& {\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}\end{array}\right.<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; .</span>$

Step 2: Starting from the N+1th time slot, the secondary user SU starts to implement the concurrent transmission and cooperative joint transmission method; according to the feedback information of the primary user receiver PR detected in the last time slot, the secondary user SU judges Whether the current time slot is the first transmission time slot of the primary user data packet: If the feedback from the primary user receiver PR is detected as an acknowledgment response ACK, it indicates that the current time slot is the first transmission time slot of the primary user data packet, go to step 3 ; If the feedback from the primary user receiver PR is detected as negative acknowledgment NAK, it indicates that the current time slot is the retransmission time slot of the primary user data packet, and step 4 is performed;

Step 3: The receiver SR of each secondary user uses the instantaneous channel information to calculate the SINR of the current secondary user SU, and judges whether the secondary user SU can transmit successfully with the primary user PU in the current time slot;

3a) The receiver SR _i of the secondary user uses the pilot signal of the primary user transmitter PT and the pilot signal of the secondary user transmitter ST _i to estimate and And calculate the SINR _i of the current secondary user:

${\mathrm{<span\; class="notranslate">\; SINR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}^{\mathrm{<span\; class="notranslate">\; max</span>}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; SR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; PT</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; SR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span>$

where P _P and The transmit power of primary user and secondary user respectively, N ₀ is the background noise power, is the instantaneous channel power gain of the i-th secondary user SU _i , The instantaneous channel power gain from the transmitter PT of the primary user to the receiver SR _i of the ith secondary user;

3b) The receiver SR _i of the secondary user compares the signal-to-interference-noise ratio SINR _i with the demodulation threshold γ _S of the secondary user data packet. If SINR _i ≥ γ _S , it indicates that the secondary user If SU _i can successfully transmit concurrently with the primary user PU, SU _i will enter set D as a candidate concurrently transmitted SU; otherwise, SU _i will remain silent in the current time slot, listening and trying to decode the data packet of the primary user;

3c) If D is an empty set, the two secondary users SU remain silent in the current time slot, listen to and try to decode the data packets of the primary user PU; if D={SU ₁ }, then SU ₁ is in the current time slot Concurrent transmission with the primary user PU, SU ₂ keeps silent, listens and tries to decode the data packet of the primary user PU; if D={SU ₂ }, then SU ₂ transmits concurrently with the primary user PU in the current time slot, and SU ₁ keeps silent , listen to and try to decode the data packets of the primary user PU; if D={SU ₁ , SU ₂ }, select and transmit the secondary user SU according to the following formula:

${\mathrm{<span\; class="notranslate">\; SU</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>\underset{{\mathrm{<span\; class="notranslate">\; SU</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; min</span>}}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; access</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; relay</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span>$

Among them, SU ^* indicates the concurrent transmission secondary user selected in the current time slot, and They are respectively used to record the number of parallel transmissions and relay times of the i-th secondary user SU _i up to the current time slot;

In the current time slot, the secondary user SU ^* is concurrently transmitted with the primary user to obtain its own throughput;

3d) The SINR is calculated by the transmitter ST _i of the secondary user not selected as the concurrent secondary user SU ^*

where ST ^* is the transmitter of the concurrent secondary user SU ^* , represents the empty set, is the transmit power of the secondary user SU ^* , The instantaneous channel power gain from the transmitter PT of the primary user to the transmitter ST _i of the ith secondary user, is the instantaneous channel power gain from the transmitter ST ^* of the secondary user to the transmitter ST _i of the i-th secondary user;

The transmitter ST _i of the secondary user will Compared with the demodulation threshold γ _P of the main user data packet, if It indicates that ST _i can successfully decode the data packet of the primary user;

Return to step 2, listen to the feedback information of the primary user receiver PR for all remaining time slot secondary users, and perform corresponding operations according to the feedback information;

Step 4: Decode the secondary user transmitter ST _i of the primary user data packet in the first transmission time slot, use the instantaneous channel information to calculate the signal-to-noise ratio of the relay channel, and judge whether the secondary user transmitter ST _i in the current time slot Can successfully relay the data packets of the primary user PU;

4a) The secondary user transmitter ST _i , which decodes the primary user data packet in the first transmission slot, estimates And calculate the signal-to-noise ratio of the primary user receiver PR

${\mathrm{<span\; class="notranslate">\; SNR</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; PR</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; PR</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ,</span>$

where _Pmax is the maximum physical power limit of the transmitter ST _i of the secondary user, PR of the receiver of the primary user, is the instantaneous channel power gain from the transmitter ST _i of the secondary user to the receiver PR of the primary user;

4b) The transmitter ST _i of the secondary user will have the signal-to-noise ratio Compared with the demodulation threshold γ _P of the main user data packet, if Then it shows that ST _i satisfies the relay condition, and ST _i will enter the set C as a candidate relay node, otherwise, ST _i remains silent in the current time slot, and the relay node of the retransmission time slot is recorded as ST ^R ;

4c) If C is an empty set, then all SUs remain silent in the retransmission time slot, and PT retransmits data packets; if C={ST ₁ }, then make ^STR =ST ₁ , and ST ₂ remains silent; if C={ ST ₂ }, then let ST ^R =ST ₂ , and ST ₁ remains silent; if C={ST ₁ ,ST ₂ }, use the following formula to determine ST ^R :

${\mathrm{<span\; class="notranslate">\; ST</span>}}^{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\underset{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; C</span>}}{\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; min</span>}}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; relay</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; access</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span>$

Among them, ST ^R represents the relay node selected by the current time slot, and They are respectively used to record the number of parallel transmissions and relay times of the i-th secondary user SU _i up to the current time slot;

In the current time slot, ST ^R acts as the relay node of the primary user, and transmits the data packets lost by the primary user in the first transmission time slot to make up for the loss caused by the secondary user to the primary user during the concurrent transmission. silent;

Returning to step 2, the secondary user listens to the feedback information of the primary user receiver PR for all remaining time slots, and performs corresponding operations according to the feedback information.

Effect of the present invention can be further illustrated by following simulation results:

1. Simulation scene

The simulation scenario of the present invention is shown in Figure 1, including a primary user PU and two secondary users SU, each primary user PU includes a primary user transmitter PT and a primary user transmitter PR, each secondary user SU Including a secondary user transmitter ST and a secondary user receiver SR, the two secondary users SU are symmetrically distributed with respect to the PU, _dp is the distance between the primary user's transmitter PT and the primary user's receiver PR , d _s is the distance between the transmitter ST _i of the secondary user and the receiver SR _i of the secondary user, i=1,2, in this simulation, d _p =1, d _s =0.5, the primary user’s The interruption threshold O _PU =0.2, the transmission power P _P of the primary user PU is equal to the maximum physical power limit P _max of the secondary user SU, that is, P _P =P _max , the demodulation threshold γ _P of the primary user data packet is equal to the maximum physical power limit P max of the secondary user SU The demodulation threshold γ _S of the data packet is equal, that is, γ _P =γ _S =1.

2. Simulation content and results

The throughput performance obtained by the primary user PU and each secondary user SU is simulated by changing the channel condition of the primary user PU. In the simulation, the average number of successfully transmitted data packets in a time slot is used to represent the throughput. By increasing the channel power gain of the primary user PU, the throughput obtained by the primary user PU and the secondary user SU is simulated. The simulation results are shown in Figure 3 Show.

3. Simulation result analysis

It can be seen from Figure 3 that with the increase of the channel power gain of the primary user PU, the throughput of the secondary user SU increases gradually, and remains unchanged after increasing to a certain extent. This is because the secondary user SU sets its own power according to the channel power gain of the primary user PU. When the channel gain of the primary user PU increases, the maximum allowable transmission power of the secondary user SU increases, so that the secondary user SU’s parallel Chances of passing increase. When the channel gain of the primary user PU increases to 25dB, in the first transmission time slot of the primary user PU data packet, there is a secondary user SU ^* that is transmitted almost every time, so the secondary user SU is under the current channel condition of the primary user PU The maximum throughput will be obtained, therefore, the secondary user SU will no longer increase with the primary user channel power gain. Since the present invention considers fairness when selecting and transmitting the secondary user SU ^* and the relay node ^STR , therefore, in this scenario, the two secondary users SU obtain the same throughput.

In the retransmission time slot of the primary user PU, the relay node ^STR relays the primary user, which to a certain extent makes up for the loss of the throughput of the primary user PU caused by the concurrent transmission of the secondary user SU ^* , reducing the The outage probability of the primary user satisfies the QoS requirement of the primary user PU well.

Claims (1)

1. A joint transmission method for concurrent transmission and collaboration in a cognitive network, comprising the following steps: (1) The secondary user sets its transmit power according to the statistical channel information of the primary user, so that when the secondary user transmits concurrently with the primary user, the outage probability of the primary user meets the outage threshold value O _PU : (1a) According to the statistical channel information, transmit power, interruption threshold and rate requirements of the primary user PU, each secondary user SU calculates the maximum allowable transmit power when transmitting concurrently with the PU through the following probability expression By calculating the maximum allowable transmit power when co-transmitting with the primary user $\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; R</span>}}{<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; R</span>}}{<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; u</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; ...</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ,</span>$ Among them, P _P is the constant transmission power of the primary user, O _PU is the interruption threshold of the primary user, N ₀ is the background noise power, |h _PT,PR | ² is the primary user’s transmitter PT to the primary user’s receiver The average channel power gain of PR, is the average channel power gain from the i-th secondary user's transmitter ST _i to the primary user's receiver PR; γ _P is the demodulation threshold of the primary user's data packet, is the maximum allowable transmit power of ST _i when concurrently transmitting with the primary user PU; In the above probability expression is the unknown, P _P , O _PU , N ₀ , γ _P , |h _PT,PR | ² and are known quantities; when the channel model is given, it can be obtained exact expression of The channel obeys the Rayleigh block fading model. Substituting the channel model into the above probability expression, the secondary user SU can obtain ${\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}}{{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; o</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; u</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>$ Among them, d _PT,PR represents the distance from the transmitter PT of the primary user to the receiver PR of the primary user, is the distance from the transmitter ST _i of the i-th secondary user to the receiver PR of the primary user, and α represents the path loss index; (1b) Combining with the maximum physical power limit P _max of the secondary user, each secondary user SU determines the final transmission power when transmitting concurrently with the primary user PU: ${\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}^{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ,</span>& {\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; \&Greater\; Equal;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}\\ {\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; ,</span>& {\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}\end{array}\right.<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; ...</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ;</span>$ (2) The secondary user listens to the acknowledgment or negative response feedback information of the primary user receiver PR, and judges whether the current time slot is the first transmission time slot or the retransmission time slot of the data packet according to the feedback information: if the previous time slot If the feedback information is an acknowledgment, then judge that the current time slot is the first transmission time slot, and perform step (3); if the feedback information of the last time slot is a negative response, then judge that the current time slot is a retransmission time slot, and perform step (4) ); (3) The receiver of the secondary user uses the instantaneous channel information to calculate the SINR _i of the current secondary user: ${\mathrm{<span\; class="notranslate">\; SINR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}^{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; SR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; SR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; ...</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ,</span>$ where P _P and The transmit power of the primary user and the secondary user, respectively, m is the number of secondary users, N ₀ is the background noise power, PT is the transmitter of the primary user, ST _i and SR _i represent the transmission of the ith secondary user tors and receivers, is the instantaneous channel power gain of the i-th secondary user SU _i , Instantaneous channel power gain from the primary user's transmitter PT to the ith secondary user receiver SR _i ; Compare the SINR _i with the demodulation threshold γ _S of the secondary user data packet, if SINR _i ≥ γ _S , the concurrent transmission condition is met, put the secondary user SU that meets the concurrent transmission condition into the set D, and put the current The concurrent transmission secondary user of the time slot is denoted as SU ^* ; If D is an empty set, all secondary users SU remain silent, listen to and try to decode the data packets of the primary user PU; if |D|=1, that is, there is only one secondary user SU in D, then the secondary user SU SU performs concurrent transmission with the primary user PU in the current time slot, and all other secondary users SU remain silent, listen to and try to decode the data packets of the primary user PU; if |D|>1, that is, there are multiple secondary users in D SU, select and transmit the secondary user SU ^* according to the following formula: ${\mathrm{<span\; class="notranslate">\; SU</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>\underset{{\mathrm{<span\; class="notranslate">\; SU</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; argmin</span>}}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; ...</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ,</span>$ Among them, |D| is the number of elements in the set D, and They are respectively used to record the concurrent transmission times and relay times of the i-th secondary user SU _i up to the current time slot, and SU ^* indicates the concurrent transmission secondary user of the current time slot; In the current time slot, the secondary user SU ^* is concurrently transmitted with the primary user PU to obtain its own throughput; The transmitter ST _i of the secondary user not selected as the concurrent secondary user SU ^* uses the instantaneous channel information to calculate the signal-to-interference-noise ratio where ST ^* is the transmitter of the concurrent secondary user SU ^* , represents the empty set, is the transmit power of the secondary user SU ^* , The instantaneous channel power gain from the primary user transmitter PT to the ith secondary user transmitter ST _i , is the instantaneous channel power gain from the secondary user's transmitter ST ^* to the i-th secondary user's transmitter ST _i ; Will Compared with the demodulation threshold γ _P of the main user data packet, if It indicates that ST _i can successfully decode the data packet of the primary user; Return to step (2), listen to the feedback information of the primary user receiver PR for all remaining time slot secondary users, and perform corresponding operations according to the feedback information; (4) The secondary user transmitter ST _i that decodes the primary user data packet in the first transmission time slot uses the instantaneous channel information to calculate the SNR of the relay channel ${\mathrm{<span\; class="notranslate">\; SNR</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; P</span>}\mathrm{<span\; class="notranslate">\; R</span>}}{<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; ,</span>$ where P _max is the maximum physical power limit of ST _i , PR is the receiver of the primary user, is the instantaneous channel power gain from the i-th secondary user's transmitter ST _i to the primary user's receiver PR; Will Compared with the demodulation threshold γ _P of the main user data packet, if It indicates that ST _i satisfies the relay condition, put the ST _i satisfying the relay condition into set C, and denote the relay node of the current time slot as ST ^R ; If C is an empty set, all SUs remain silent in the retransmission time slot, and PT retransmits the data packet; if |C|=1, the transmitter ST of the secondary user entering the set C acts as the relay node ST of the primary user ^R , the primary user retransmits the data packet, and the primary user and other secondary users remain silent in the current time slot; if |C|>1, that is, there are multiple STs in the set C that meet the relay condition, the following formula is used to determine the primary User's relay node ST ^R : ${\mathrm{<span\; class="notranslate">\; ST</span>}}^{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; =</span>\underset{{\mathrm{<span\; class="notranslate">\; ST</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Element;</span>\mathrm{<span\; class="notranslate">\; C</span>}}{\mathrm{<span\; class="notranslate">\; argmin</span>}}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; the\; y</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>$ Among them, |C| is the number of elements in the set C, In the current time slot, ST ^R acts as the relay node of the primary user, and transmits the data packets lost by the primary user in the first transmission time slot to make up for the loss caused by the secondary user to the primary user during the concurrent transmission. silent; Returning to step (2), the secondary user listens to the feedback information of the primary user receiver PR for all remaining time slots, and performs corresponding operations according to the feedback information.