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

Abstract

The invention discloses and be applied to a kind of of cognition network and pass and the joint transmission method that cooperates, mainly solve the existing transmission strategy handling capacity that secondary user's obtains when primary user's channel condition is good based on the design of automatic repeat request agreement ARQ little, and the loss of throughput of primary user is not had balanced problem.It has main steps that: 1. secondary user's arranges transmitting power, it is ensured that the outage probability of primary user meets interrupt gate limit value；2. secondary user's intercepts the feedback information of primary user, it is judged that current time slots still retransmits time slot for transmission time slot first；Transmission time slot first, secondary user's and primary user also pass, it is thus achieved that handling capacity；4. retransmitting time slot, secondary user's is that primary user relays, interference when compensating and pass caused primary user.The present invention makes primary user improve the handling capacity of secondary user's on the premise of obtaining minimum throughout loss, and the loss of throughput of primary user is had certain compensation, can be used for improving the efficiency of transmission of cognition network.

Description

Cognition network is carried out and passes and the joint transmission method cooperated

Technical field

The invention belongs to wireless communication technology field, relate to the joint transmission method of cognition network, can be used for cognitive nothing Line electric network.

Background technology

It is main that cognitive radio networks allows secondary user's to utilize on the premise of the service quality QoS ensureing primary user The frequency spectrum resource of user carries out chance transmission.In primary user's system based on automatic repeat request agreement ARQ, Secondary user's is by intercepting the data transmission information of primary user and confirming that response ACK or negative response NAK etc. feed back The present transmission state of acquisition of information primary user, under conditions of ensureing that the interference to primary user is less than certain threshold value, Carry out chance access.Existing major part document, when studying the access mechanism of secondary user's, the most all uses as follows Transmission method: when primary user is transmitted first, secondary user's is intercepted the transmission of primary user, and is attempted decoding primary user Packet；When primary user's data transmission fails for the first time needs to retransmit, if secondary user's can decode primary The packet at family, then retransmit time slot primary user, and secondary user's transmits the packet of oneself simultaneously, and utilizes interference Technology for eliminating improves the transmission success rate of secondary user's.

In this approach, secondary user's utilizes the re-transmission time slot of primary user, it is achieved the access of channel.Only work as master When user's loading error occurring first needs to retransmit, secondary user's is just had an opportunity to access channel and is realized and primary user's parallel transmission. This method is only when the channel condition of primary user is poor, and secondary user's could obtain more access chance；When When the channel condition of primary user is preferable, the probability that primary user retransmits is the lowest, thus the obtainable conveyer of secondary user's Can be by seldom.And, secondary user's causes certain loss to the handling capacity of primary user in this approach, and There is no any compensation.

Summary of the invention

The shortcoming that present invention aims to above-mentioned prior art, propose a kind of cognition network to be carried out and passes and The joint transmission method of cooperation, to improve the handling capacity of secondary user's, makes up the loss of throughput causing primary user.

The technical scheme is that and be achieved in that:

One. term illustrates:

PU:Primary User, primary user,

PT:Primary Transmitter, the emitter of primary user,

PR:Primary Receiver, the receptor of primary user,

SU:Secondary User, secondary user's,

ST:Secondary Transmitter, the emitter of secondary user's,

SR:Secondary Receiver, the receptor of secondary user's,

ARQ:Automatic Repeat-reQuest, automatic repeat request,

QoS:Quality of Service, service quality,

ACK:ACKnowledgement, confirms response,

NAK:Non-ACKnowledgement, negative response,

Two. technical thought

At the transmission time slot first of main user data bag, by secondary user's and primary user and pass, it is thus achieved that secondary user's Handling capacity；At the re-transmission time slot of main user data bag, secondary user's is relayed as primary user, makes up and pass Time loss of throughput that primary user is caused.

Three. transmission method of the present invention, comprise the steps:

(1) secondary user's is according to the statistic channel information of primary user, arranges the transmitting power of oneself so that secondary use Family and primary user when passing, it is ensured that the outage probability of primary user meets interrupt gate limit value O_PU；

(2) secondary user's intercepts confirmation response or the negative response feedback information of primary user receptor PR, anti-according to this Feedforward information judges that the transmission time slot first that current time slots is packet still retransmits time slot: if the feedback of last time slot Information is for confirming response, then sentencing current time slots is transmission time slot, execution step (3) first；If last time slot Feedback information is negative response, then sentence current time slots for re-transmission time slot, execution step (4)；

(3) receptor of secondary user's utilizes transient channel information to calculate the Signal to Interference plus Noise Ratio SINR of current secondary user's_i:

${\mathrm{SINR}}_i=\frac{P_{{\mathrm{ST}}_i}^{\max }{\left|h_{{\mathrm{ST}}_i,{\mathrm{SR}}_i}\right|}^2}{N_0+P_P{\left|h_{\mathrm{PT},{\mathrm{SR}}_i}\right|}^2},i=\mathrm{1,2},...m$

Wherein P_PWithBeing respectively primary user and the transmitting power of secondary user's, m is the number of secondary user's, N₀ For Background Noise Power, PT is the emitter of primary user, ST_iAnd SR_iRepresent the transmitting of i-th secondary user's respectively Device and receptor,For i-th secondary user's SU_iTransient channel power gain,For primary user Emitter PT to i-th secondary user's receptor SR_iTransient channel power gain；

By SINR_iDemodulation threshold value γ with secondary user's packet_SCompare, if SINR_i≥γ_S, then meet And pass condition, put into set D by meeting and passing secondary user's SU of condition, by current time slots and pass secondary use Family is denoted as SU^*；

If D is empty set, the most all secondary user's SU all keep mourning in silence, and intercept and attempt to decode primary user PU Packet；If only one of which secondary user's SU in | D |=1, i.e. D, then this secondary user's SU is when current Gap carries out with primary user PU and passes, and other all secondary user's SU keep mourning in silence, and intercept and attempt to decode primary The packet of family PU；If | D | ＞ 1, i.e. D have multiple secondary user's SU, then select according to below equation And pass secondary user's SU^*:

${\mathrm{SU}}^{*}=\underset{{\mathrm{SU}}_i\∈D}{\arg \min }\frac{T_i^{\mathrm{access}}}{T_i^{\mathrm{relay}}+1},i\∈\{\mathrm{1,2},...m\},$

Wherein, | D | is the element number in set D,WithIt is respectively intended to record i-th secondary user's SU_iTo current time slots and pass number of times and handover number, SU^*Represent current time slots and pass secondary user's；

In current time slots, and pass secondary user's SU^*With primary user PU passing, it is thus achieved that the handling capacity of oneself；

It is not chosen as and passes secondary user's SU^*The emitter ST of secondary user's_iTransient channel information is utilized to calculate letter Dry ratio of making an uproar:

Wherein ST^*For and pass secondary user's SU^*Emitter,Represent empty set,For and pass secondary user's SU^*Transmitting power,For primary user emitter PT to i-th secondary user's emitter ST_iInstantaneous letter Road power gain,For and pass the emitter ST of secondary user's^*To i-th secondary user's emitter ST_iWink Time channel power gain；

WillDemodulation threshold value γ with main user data bag_PCompare, ifThen Show ST_iThe packet of primary user can be successfully decoded out；

Return step (2), remaining all time slot secondary user's intercepted the feedback information of primary user receptor PR, And perform corresponding operating according to feedback information；

(4) ST of main user data bag is decoded at transmission time slot first_i, utilize transient channel information to calculate relaying letter The signal to noise ratio in road

${\mathrm{SNR}}_{{\mathrm{ST}}_i,\mathrm{PR}}=\frac{P_{\max }{\left|h_{{\mathrm{ST}}_i,\mathrm{PR}}\right|}^2}{N_0},$

Wherein P_maxFor ST_iGreatest physical Power Limitation, PR is the receptor of primary user,For i-th The emitter ST of secondary user's_iTransient channel power gain to the receptor PR of primary user；

WillDemodulation threshold value γ with main user data bag_PCompare, ifThen table Bright ST_iMeet relay condition, the ST of relay condition will be met_iPut into set C, the via node of current time slots is remembered Make ST^R；

If C is empty set, then keeping mourning in silence at the re-transmission all SU of time slot, PT retransmits packet；If | C |=1, Then enter the emitter ST via node ST as primary user of the secondary user's gathering C^R, retransmit for primary user Packet, primary user and other secondary user's keep mourning in silence in current time slots；If | C | ＞ 1, i.e. set C had Multiple ST meet relay condition, then utilize equation below to determine the via node ST of primary user^R:

${\mathrm{ST}}^R=\underset{{\mathrm{ST}}_i\∈C}{\arg \min }\frac{T_i^{\mathrm{relay}}}{T_i^{\mathrm{access}}+1},$

Wherein, | C | is the element number in set C,

At current time slots, ST^RAs the via node of primary user, transmission primary user lose at transmission time slot first Packet, the loss that when making up and pass, primary user is caused by secondary user's, primary user keeps mourning in silence in current time slots；

Return step (2), remaining all time slot secondary user's intercepted the feedback information of primary user receptor PR, And perform corresponding operating according to feedback information.

Present invention have the advantage that

1. the present invention uses and passes and the joint transmission method cooperated so that secondary user's is along with primary user's channel gain Raising, it is thus achieved that handling capacity be gradually increased.

2. in the present invention, secondary user's utilizes the statistic channel information of primary user, arranges the transmitting power of oneself with full The interrupt gate limit value of foot primary user so that secondary user's with primary user when passing, it is ensured that the QoS of primary user Demand.

3. present invention utilizes cooperating, primary user between primary and secondary level user and between different secondary user's Re-transmission time slot, secondary user's by for primary user relay, when compensate for a certain extent and pass, primary user is gulped down The loss that the amount of telling causes, and make primary user reach to save the purpose of power；By utilizing transient channel information, secondary Respective handling capacity is obtained with having an opportunity per family.

4. the present invention is when there being multiple secondary user's meet and pass condition, and prioritizing selection is that primary user's handover number is many Secondary user's as and pass secondary user's, when there being multiple secondary user's to meet relay condition, prioritizing selection also passes time Several many secondary user's, as via node, embody the fairness between different secondary user's.

Accompanying drawing explanation

Fig. 1 is the cognition network scene graph that the present invention uses；

Fig. 2 be the present invention's and pass and the joint transmission method flow chart cooperated；

Fig. 3 is the simulation result figure of the present invention.

Detailed description of the invention

With reference to Fig. 1, the simulating scenes of the present invention comprises a primary user and two secondary user's, i.e. takes m=2, Primary user includes an a primary user emitter PT and primary user receptor PR, and each secondary user's includes one A secondary user's emitter ST and secondary user's receptor SR, the wherein emitter of i-th secondary user's and connecing Receive device and be expressed as ST_iAnd SR_i, the linkage length of primary user is d_p, the linkage length of each secondary user's is d_s； Primary user uses stop-and-wait-ARQ agreement to be transmitted, and not limits number of retransmissions, and secondary user's is by intercepting The feedback information of primary user's receptor performs and passes and the joint transmission method that cooperates.

With reference to Fig. 2, the present invention's and biography and the joint transmission method that cooperates, comprise the following steps that

Step 1: secondary user's, according to the statistic channel information of primary user, arranges the transmitting power of oneself so that secondary Level user and primary user when passing, it is ensured that the outage probability of primary user meets interrupt gate limit value O_PU；

1a) secondary user's persistently intercepts N number of time slot, and N is positive integer, the feedback information of statistics primary user's receptor, According to the feedback information of primary user's receptor, the transmitting power of primary user, interrupt gate limit value and rate requirement, estimate |h_PT,PR|²WithWherein | h_PT,PR|²For the emitter PT of primary user to receptor PR average of primary user Channel power gain,Emitter ST for i-th secondary user's_iReceptor PR average to primary user Channel power gain；

1b) utilization of secondary user's SU estimates | h_PT,PR|²WithThe transmitting power P of primary user PU_P、 Interrupt gate limit value O_PUAnd rate requirement, calculate permitting with primary user maximum when passing by following probability expression Permitted to launch power

$P(\frac{P_P{\left|h_{\mathrm{PT},\mathrm{PR}}\right|}^2}{N_0+{\stackrel{\&OverBar;}{P}}_{{\mathrm{ST}}_i}{\left|h_{{\mathrm{ST}}_i,\mathrm{PR}}\right|}^2}<{\mathrm{\&gamma;}}_P)=O_{\mathrm{PU}},i=\mathrm{1,2},$

Wherein, P_PFor the constant emission power of primary user, O_PUFor the interrupt gate limit value of primary user, N₀For background Noise power, γ_PFor the demodulation threshold value of main user data bag,Emitter ST for i-th secondary user's_i? With primary user PU maximum allowable transmitting power when passing；

In above-mentioned probability expressionFor unknown number, P_P, O_PU, N₀, γ_P, | h_PT,PR|²WithIt is Known quantity；When given channel model, it can be deduced thatExact expression.

In the present embodiment, channel obeys Rayleigh block fading model, is substituted into by channel model in above-mentioned probability expression, Secondary user's SU draws

${\stackrel{\&OverBar;}{P}}_{{\mathrm{ST}}_i}=\left(\frac{P_P/d_{\mathrm{PT},\mathrm{PR}}^{\mathrm{\&alpha;}}}{{\mathrm{\&gamma;}}_P/d_{{\mathrm{ST}}_i,\mathrm{PR}}^{\mathrm{\&alpha;}}}\right)(\frac{\exp (-\frac{{\mathrm{\&gamma;}}_P{N}_0}{P_P/d_{\mathrm{PT},\mathrm{PR}}^{\mathrm{\&alpha;}}})}{1-O_{\mathrm{PU}}}-1),i=\mathrm{1,2},$

Wherein, d_PT,PRRepresent the distance of the emitter PT to the receptor PR of primary user of primary user,It is The emitter ST of i secondary user's_iTo the distance of the receptor PR of primary user, α represents path loss index；

1c) combine greatest physical Power Limitation P of secondary user's SU_max, each secondary user's SU determine with Primary user PU also finally launches power when passing:

$P_{{\mathrm{ST}}_i}^{\max }=\left\{\begin{array}{cc}{P}_{\max },& {\stackrel{\&OverBar;}{P}}_{{\mathrm{ST}}_i}\&GreaterEqual;P_{\max }\\ {\stackrel{\&OverBar;}{P}}_{{\mathrm{ST}}_i},& {\stackrel{\&OverBar;}{P}}_{{\mathrm{ST}}_i}<P_{\max }\end{array}\right.,i=\mathrm{1,2}.$

Step 2: from the beginning of the N+1 time slot, secondary user's SU starts to perform and pass and the joint transmission side that cooperates Method；According to the feedback information of the primary user receptor PR that last time slot listens to, secondary user's SU judges current Whether time slot is the transmission time slot first of main user data bag: if listening to being fed back to of primary user receptor PR Confirm response ACK, then show the transmission time slot first that current time slots is main user data bag, perform step 3；As Really listen to primary user receptor PR is fed back to negative response NAK, then show that current time slots is main user data The re-transmission time slot of bag, performs step 4；

Step 3: the receptor SR of each secondary user's utilizes transient channel information to calculate current secondary user's SU Signal to Interference plus Noise Ratio, it is judged that whether can be with primary user PU passing successfully in this secondary user's SU of current time slots；

3a) the receptor SR of secondary user's_iUtilize pilot signal and the secondary user's emitter of primary user emitter PT ST_iPilot signal, estimate respectivelyWithAnd calculate the Signal to Interference plus Noise Ratio of current secondary user's SINR_i:

${\mathrm{SINR}}_i=\frac{P_{{\mathrm{ST}}_i}^{\max }{\left|h_{{\mathrm{ST}}_i,{\mathrm{SR}}_i}\right|}^2}{N_0+P_P{\left|h_{\mathrm{PT},{\mathrm{SR}}_i}\right|}^2},i=\mathrm{1,2},$

Wherein P_PWithIt is respectively primary user and the transmitting power of secondary user's, N₀For Background Noise Power,For i-th secondary user's SU_iTransient channel power gain,Emitter PT for primary user Receptor SR to i-th secondary user's_iTransient channel power gain；

3b) the receptor SR of secondary user's_iBy Signal to Interference plus Noise Ratio SINR_iDemodulation threshold value γ with secondary user's packet_S Compare, if SINR_i≥γ_S, then show in current time slots secondary user's SU_iCan be with primary user PU passing into Merit, SU_iTo alternately and pass SU and enter set D；Otherwise, SU_iKeep mourning in silence in current time slots, intercept also Attempt the packet of decoding primary user；

If 3c) D is empty set, then two secondary user's SU all keep mourning in silence in current time slots, intercept and attempt to solve The packet of code primary user PU；If D={SU₁, then SU₁At current time slots and primary user PU and pass, SU₂Protect Hold and mourn in silence, intercept and attempt to decode the packet of primary user PU；If D={SU₂, then SU₂Current time slots with Primary user PU also passes, SU₁Holding is mourned in silence, and intercepts and attempt to decode the packet of primary user PU；If D={SU₁,SU₂, then select and pass secondary user's SU according to below equation:

${\mathrm{SU}}^{*}=\underset{{\mathrm{SU}}_i\&Element;D}{\arg \min }\frac{T_i^{\mathrm{access}}}{T_i^{\mathrm{relay}}+1},i=\mathrm{1,2},$

Wherein, SU^*Represent that current time slots is selected and pass secondary user's,WithIt is respectively intended to record I-th secondary user's SU_iTo current time slots and pass number of times and handover number；

In current time slots, and pass secondary user's SU^*With primary user passing, it is thus achieved that the handling capacity of oneself；

3d) it is not chosen as and passes secondary user's SU^*Secondary user's, by its emitter ST_iCalculate Signal to Interference plus Noise Ratio

Wherein ST^*For and pass secondary user's SU^*Emitter,Represent empty set,For and pass secondary user's SU^*Transmitting power,Emitter PT to the emitter ST of i-th secondary user's for primary user_iWink Time channel power gain,For and pass the emitter ST of secondary user's^*Emitter to i-th secondary user's ST_iTransient channel power gain；

The emitter ST of secondary user's_iWillDemodulation threshold value γ with main user data bag_PCompare, IfThen show ST_iThe packet of primary user can be successfully decoded out；

Return step 2, remaining all time slot secondary user's are intercepted the feedback information of primary user receptor PR, and Corresponding operating is performed according to feedback information；

Step 4: decode the secondary user's emitter ST of main user data bag at transmission time slot first_i, utilize instantaneous Channel information calculates the signal to noise ratio of trunk channel, it is judged that at current time slots this secondary user's emitter ST_iWhether can be successful The packet of relaying primary user PU；

The secondary user's emitter ST of main user data bag 4a) is decoded at transmission time slot first_i, estimate And calculate the signal to noise ratio of primary user receptor PR

${\mathrm{SNR}}_{{\mathrm{ST}}_i,\mathrm{PR}}=\frac{P_{\max }{\left|h_{{\mathrm{ST}}_i,\mathrm{PR}}\right|}^2}{N_0},i\&Element;\left\{\mathrm{1,2}\right\},$

Wherein P_maxEmitter ST for secondary user's_iGreatest physical Power Limitation, PR is the receptor of primary user,Emitter ST for secondary user's_iTransient channel power gain to primary user receptor PR；

4b) the emitter ST of secondary user's_iBy signal to noise ratioDemodulation threshold value γ with main user data bag_P Compare, ifThen show ST_iMeet relay condition, ST_iBy alternately via node Enter set C, otherwise, ST_iKeep mourning in silence in current time slots, the via node retransmitting time slot is denoted as ST^R；

If 4c) C is empty set, then keeping mourning in silence at the re-transmission all SU of time slot, PT retransmits packet；If C={ST₁, then make ST^R=ST₁, ST₂Holding is mourned in silence；If C={ST₂, then make ST^R=ST₂, ST₁Protect Hold and mourn in silence；If C={ST₁,ST₂, then utilize equation below to determine ST^R:

${\mathrm{ST}}^R=\underset{{\mathrm{ST}}_i\&Element;C}{\arg \min }\frac{T_i^{\mathrm{relay}}}{T_i^{\mathrm{access}}+1},i=\mathrm{1,2},$

Wherein, ST^RRepresent the via node that current time slots is selected,WithIt is respectively intended to record i-th Individual secondary user's SU_iTo current time slots and pass number of times and handover number；

At current time slots, ST^RAs the via node of primary user, transmission primary user lose at transmission time slot first Packet, the loss that when making up and pass, primary user is caused by secondary user's, primary user keeps mourning in silence in current time slots；

Return step 2, remaining all time slot secondary user's are intercepted the feedback information of primary user receptor PR, and Corresponding operating is performed according to feedback information.

The effect of the present invention can further illustrate with following simulation result:

1. simulating scenes

The simulating scenes of the present invention is as it is shown in figure 1, include a primary user PU and two secondary user's SU, each Primary user PU includes a primary user emitter PT and a primary user emitter PR, each secondary user's SU Including an a secondary user's emitter ST and secondary user's receptor SR, two secondary user's SU relative to PU is symmetric, d_pFor the distance between the emitter PT and the receptor PR of primary user of primary user, d_sFor The emitter ST of secondary user's_iReceptor SR to secondary user's_iBetween distance, i=1,2, in this emulation, d_p=1, d_s=0.5, the interruption thresholding O of primary user_PUThe transmitting power P of=0.2, primary user PU_PUse with secondary Greatest physical Power Limitation P of family SU_maxEqual, i.e. P_P=P_max, the demodulation threshold γ of main user data bag_PWith The demodulation threshold γ of secondary user's packet_SEqual, i.e. γ_P=γ_S=1.

2. emulation content and result

By changing the channel condition of primary user PU, emulate what primary user PU and each secondary user's SU obtained Throughput performance.In using a time slot in emulation, the number-of-packet of average Successful transmissions represents handling capacity, passes through Improve the channel power gain of primary user PU, emulate primary user PU and the handling capacity of secondary user's SU acquisition, Simulation result is as shown in Figure 3.

3. analysis of simulation result

From figure 3, it can be seen that along with the raising of primary user's PU channel power gain, gulping down of secondary user's SU The amount of telling is gradually increased, and increases to and keeps constant the most afterwards.This is because, secondary user's SU is according to primary user The channel power gain of PU arranges the power of oneself, when the channel gain of primary user PU improves, and secondary user's The maximum of SU can allow launch power increase, thus secondary user's SU and pass chance increase.As primary user PU Channel gain when increasing to 25dB, at the transmission time slot first of primary user's PU packet, the most all exist And pass secondary user's SU^*, therefore secondary user's SU will obtain maximum under the current channel condition of primary user PU Handling capacity, therefore, secondary user's SU will no longer increase along with the raising of primary user's channel power gain.Due to The present invention is selecting and is passing secondary user's SU^*With via node ST^RTime consider fairness, therefore, in this scene In, two secondary user's SU obtain identical handling capacity.

Due to the re-transmission time slot at primary user PU, via node ST^RRelay for primary user, to a certain degree On compensate for and pass secondary user's SU^*The loss causing the handling capacity of primary user PU, reduces in primary user Disconnected probability, thus meet the QoS requirement QoS of primary user PU well.

Claims (1)

1. cognition network carried out and pass and the joint transmission method cooperated, comprising the following steps:

(1) secondary user's is according to the statistic channel information of primary user, arranges the transmitting power of oneself so that secondary user's is with primary Family when passing, it is ensured that the outage probability of primary user meets interrupt gate limit value O_PU:

(1a) each secondary user's SU is wanted according to statistic channel information, transmitting power, interrupt gate limit value and the speed of primary user PU Ask, by following probability expression calculate with PU maximum allowable transmitting power when passingBy calculating with primary Family maximum allowable transmitting power when passing

$P\left(\frac{P_P|h_{PT,PR}{|}^2}{N_0+{\stackrel{\&OverBar;}{P}}_{{\mathrm{ST}}_i}|h_{{\mathrm{ST}}_i,PR}{|}^2}<{\mathrm{\&gamma;}}_P\right)=O_{PU},i=1,2,...,m,$

Wherein, P_PFor the constant emission power of primary user, O_PUFor the interrupt gate limit value of primary user, N₀For Background Noise Power, |h_PT,PR|²For the average channel power gain of the emitter PT to the receptor PR of primary user of primary user,Secondary for i-th The emitter ST of user_iAverage channel power gain to the receptor PR of primary user；γ_PFor the demodulation threshold value of main user data bag,For with primary user PU ST when passing_iMaximum allowable transmitting power；

In above-mentioned probability expressionFor unknown number, P_P, O_PU, N₀, γ_P, | h_PT,PR|²WithIt is known quantity； When given channel model, can drawExact expression；

Channel obeys Rayleigh block fading model, is substituted in above-mentioned probability expression by channel model, and secondary user's SU draws

${\stackrel{\&OverBar;}{P}}_{{\mathrm{ST}}_i}=\left(\frac{P_P/d_{PT,PR}^{\mathrm{\&alpha;}}}{{\mathrm{\&gamma;}}_P/d_{{\mathrm{ST}}_i,PR}^{\mathrm{\&alpha;}}}\right)\left(\frac{\exp \left(-\frac{{\mathrm{\&gamma;}}_P{N}_0}{P_P/d_{PT,PR}^{\mathrm{\&alpha;}}}\right)}{1-O_{PU}}-1\right),i=1,2,$

Wherein, d_PT,PRRepresent the distance of the emitter PT to the receptor PR of primary user of primary user,Use for i-th secondary The emitter ST at family_iTo the distance of the receptor PR of primary user, α represents path loss index；

(1b) greatest physical Power Limitation P of secondary user's is combined_max, each secondary user's SU determine with primary user PU passing Time finally launch power:

$P_{{\mathrm{ST}}_i}^{\max }=\left\{\begin{array}{cc}{P}_{max},& {\stackrel{\&OverBar;}{P}}_{{\mathrm{ST}}_i}\&GreaterEqual;P_{max}\\ {\stackrel{\&OverBar;}{P}}_{{\mathrm{ST}}_i},& {\stackrel{\&OverBar;}{P}}_{{\mathrm{ST}}_i}<P_{max}\end{array}\right.,i=1,2,...m;$

(2) secondary user's intercepts confirmation response or the negative response feedback information of primary user receptor PR, sentences according to this feedback information Disconnected current time slots is that the transmission time slot first of packet still retransmits time slot: if the feedback information of last time slot is for confirming response, Then sentencing current time slots is transmission time slot, execution step (3) first；If the feedback information of last time slot is negative response, then sentence Current time slots, for retransmitting time slot, performs step (4)；

(3) receptor of secondary user's utilizes transient channel information to calculate the Signal to Interference plus Noise Ratio SINR of current secondary user's_i:

${\mathrm{SINR}}_i=\frac{P_{{\mathrm{ST}}_i}^{\max }|h_{{\mathrm{ST}}_i,{\mathrm{SR}}_i}{|}^2}{N_0+P_P|h_{PT,{\mathrm{SR}}_i}{|}^2},i=1,2,...m,$

Wherein P_PWithBeing respectively primary user and the transmitting power of secondary user's, m is the number of secondary user's, N₀Make an uproar for background Acoustical power, PT is the emitter of primary user, ST_iAnd SR_iRepresent emitter and the receptor of i-th secondary user's respectively, For i-th secondary user's SU_iTransient channel power gain,Emitter PT for primary user connects to i-th secondary user's Receive device SR_iTransient channel power gain；

By SINR_iDemodulation threshold value γ with secondary user's packet_SCompare, if SINR_i≥γ_S, then meet and pass condition, Put into set D by meeting and passing secondary user's SU of condition, by current time slots and pass secondary user's and be denoted as SU^*；

If D is empty set, the most all secondary user's SU all keep mourning in silence, and intercept and attempt to decode the packet of primary user PU； If only one of which secondary user's SU in | D |=1, i.e. D, then this secondary user's SU is carried out with primary user PU in current time slots And pass, other all secondary user's SU keep mourning in silence, and intercept and attempt to decode the packet of primary user PU；If | D | > 1, I.e. D has multiple secondary user's SU, then selects according to below equation and pass secondary user's SU^*:

${\mathrm{SU}}^{*}=\underset{{\mathrm{SU}}_i\&Element;D}{\mathrm{argmin}}\frac{T_i^{access}}{T_i^{relay}+1},i\&Element;\{1,2,...m\},$

Wherein, | D | is the middle element number of set D,WithIt is respectively intended to record i-th secondary user's SU_iTo current Till time slot and pass number of times and handover number, SU^*Represent current time slots and pass secondary user's；

In current time slots, and pass secondary user's SU^*With primary user PU passing, it is thus achieved that the handling capacity of oneself；

It is not chosen as and passes secondary user's SU^*The emitter ST of secondary user's_iTransient channel information is utilized to calculate Signal to Interference plus Noise Ratio

Wherein ST^*For and pass secondary user's SU^*Emitter,Represent empty set,For and pass secondary user's SU^*Transmitting Power,For primary user emitter PT to i-th secondary user's emitter ST_iTransient channel power gain, For and pass the emitter ST of secondary user's^*To i-th secondary user's emitter ST_iTransient channel power gain；

WillDemodulation threshold value γ with main user data bag_PCompare, ifThen show ST_iEnergy The packet of primary user is successfully decoded out；

Return step (2), remaining all time slot secondary user's are intercepted the feedback information of primary user receptor PR, and according to feedback Information performs corresponding operating；

(4) the secondary user's emitter ST of main user data bag is decoded at transmission time slot first_i, utilize transient channel information to calculate The signal to noise ratio of trunk channel

${\mathrm{SNR}}_{{\mathrm{ST}}_i,PR}=\frac{P_{max}|h_{{\mathrm{ST}}_i,PR}{|}^2}{N_0},$

Wherein P_maxFor ST_iGreatest physical Power Limitation, PR is the receptor of primary user,For i-th secondary user's Emitter ST_iTransient channel power gain to the receptor PR of primary user；

WillDemodulation threshold value γ with main user data bag_PCompare, ifThen show ST_iFull Foot relay condition, will meet the ST of relay condition_iPut into set C, the via node of current time slots is denoted as ST^R；

If C is empty set, then keeping mourning in silence at the re-transmission all SU of time slot, PT retransmits packet；If | C |=1, then enter set The emitter ST of the secondary user's of C is as the via node ST of primary user^R, retransmit packet for primary user, primary user and other Secondary user's keeps mourning in silence in current time slots；If | C | > 1, i.e. set C have multiple ST to meet relay condition, then utilize as follows Formula determines the via node ST of primary user^R:

${\mathrm{ST}}^R=\underset{{\mathrm{ST}}_i\&Element;C}{\mathrm{argmin}}\frac{T_i^{relay}}{T_i^{access}+1},$

Wherein, | C | is the element number in set C,

At current time slots, ST^RAs the via node of primary user, transmit the packet that primary user loses at transmission time slot first, The loss that when making up and pass, primary user is caused by secondary user's, primary user keeps mourning in silence in current time slots；

Return step (2), remaining all time slot secondary user's are intercepted the feedback information of primary user receptor PR, and according to feedback Information performs corresponding operating.