CN104394534A - Two-stage central cooperative frequency spectrum sharing mechanism based on priority queue - Google Patents

Abstract

The invention discloses a two-stage central cooperative frequency spectrum sharing mechanism based on a priority queue. A cooperative cognitive radio network comprises a pair of master users and a plurality of cognitive user pairs, wherein the master users assist with authorized communication through recruiting the cognitive users as relay, and through management cooperation, the cooperative cognitive users coordinate access of other uncooperative cognitive users, so that a two-stage central management structure formed by the master users and the cooperative cognitive users is formed. According to the two-stage central cooperative frequency spectrum sharing mechanism, through designing selection and updating of the cooperative cognitive users and data transmission control with different priorities, dynamic and highly-efficient frequency spectrum sharing of many types of nodes can be implemented under the condition of stronger business randomness.

Description

A kind of two-stage center collaboration frequency spectrum shared mechanism based on priority query

Technical field

The present invention relates to mobile communication technology field, be specifically related to a kind of two-stage center collaboration frequency spectrum shared mechanism based on priority query.

Background technology

Along with the fast development of wireless communication technology, the frequency spectrum be not assigned with is fewer and feweri, and the problem of frequency spectrum resource shortage highlights day by day.Meanwhile, according to FCC (Federal Communications Commission, FCC) survey report display, the frequency spectrum service efficiency of below 3GHz is in 15% ~ 85% scope, and the availability of frequency spectrum of 3-6GHz is less than 0.5%, the total availability of frequency spectrum of various wireless system is below 10%.Relative to limited frequency spectrum resource, low frequency spectrum utilance causes the serious wasting of resources.Cognitive radio (Cognitiveradio, CR) has the dynamic spectrum technology of sharing of good prospect as one, can effectively solve above-mentioned contradiction, receive extensive concern in recent years.

In the cognitive communications of reality, primary user's transmitter P _tits destination node P of potential range _rcomparatively far away, or the link between sending and receiving end is stopped by building and signal experiences deep fading etc., thus cause link-quality to support P _tto P _rdirect communication.Document K Letaief, ZWei.Cooperative communications for cognitive radio networks [J] .Proceedings of the IEEE, 2009, point out in 97 (5): 878-893 (collaboration communications of cognitive radio networks), primary user can recruit qualified cognitive user and assist it to complete communication as relaying.As return cognitive user being provided to assistance, primary user permits that cognitive user uses a part of communication resource, as the channel etc. in the time slot in time domain shared mechanism, frequency domain shared mechanism, to complete cognitive transmission.Above-mentioned scene is called cooperative cognitive wireless network (Cooperative Cognitive Radio Networks, CCRN), by designing corresponding cooperation transmission mechanism, the communication quality of primary user can be improved, making cognitive user obtain communication opportunity simultaneously.

Although such scheme can realize main secondary user's, the efficient of the communication resource is shared, but still there are some problems.First, the data of main secondary user's send the moment being limited in transmission cycle, and the randomness that business arrives may cause the part in certain stage, and even All Time is idle, causes the wasting of resources.Secondly, existing cooperation transmission mechanism only studies the resource-sharing between authorized user with the cognitive nodes participating in cooperating, do not relate to the Resourse Distribute of the cognitive nodes having neither part nor lot in cooperation, it is random and limited for participating on the one hand the cognitive nodes quantity of cooperation and business transmission demand thereof, channel access authority as return may not obtain making full use of of cooperative cognitive node, on the other hand, have neither part nor lot in cooperation in system in a large number but have the cognitive nodes of communication requirement cannot access idle frequency spectrum.

Document A Gamini, T Zahir, Z Panlop and A Zomaya.Performanceanalys is of EDF schedul ing in a multi-priority preemptive M/G/1queue [J] .IEEE Transactions on Parallel and D istributedSystems, 2013, the behavior modeling in 25 (8): 2149-2158 (performance evaluations of the EDF scheduling of multipriority preemptive type M/G/1 queue), traffic packets being arrived node is Poisson process, devise collaboration frequency spectrum and share method, and use the M/G/1 queuing model with priority to analyze delay performance, but in the solution in question, cooperative cognitive user is competitive channel common with other cognitive user after assistance primary user is transmitted, there is no due return, also unfair for cooperative cognitive user.

Summary of the invention

For the deficiencies in the prior art, the present invention aims to provide a kind of two-stage center collaboration frequency spectrum shared mechanism based on priority query, solve the resource allocation problem not taking into full account cooperative cognitive node and non-cooperating cognitive nodes in existing frequency spectrum share scheme, and dynamic, the high-efficiency frequency spectrum that realize polytype node when business randomness is stronger are shared.

To achieve these goals, the present invention adopts following technical scheme:

A kind of process of the two-stage center collaboration frequency spectrum shared mechanism based on priority query is as follows:

Step 1, selecting collaboration cognitive user, specifically comprises the steps:

Step 1.1, primary user's transmitter P _tperipherad cognitive user broadcast relay recruits request grouping, and this grouping comprises primary user's receiver P _rinformation;

Step 1.2, receives this request and the cognitive user being ready to serve as relaying sends cooperation call request grouping, in its communication range, find P _r;

Step 1.3, works as P _rafter receiving the call request from least one relaying cognitive user, P _rcarry out broadcast response;

Step 1.4, can receive P _trelaying recruit request and P _rthe cognitive user of response possesses the condition of relaying, P _taccording to the Link State relevant with candidate's cooperative cognitive user obtained, according to the criterion selecting collaboration cognitive user that end-to-end data rate is maximum;

Step 2, P _tcarry out transfer of data, mainly comprise P _t→ S ^rand S ^r→ P _rin two stages, the sequencing of the two is fixed and recurs, S ^rfor cooperative cognitive user; At the initial time of each time slot, as long as P _tthere is grouping to arrive, just send data immediately;

Step 3, cooperative cognitive user S ^rcarry out transfer of data, first to P _tgrouping forward, then according to mandate business situation is taken to channel, carries out the transmission of its data;

Step 4, non-cooperating cognitive user carries out transfer of data: as cooperative cognitive user S ^rwhen channel idle being detected and self there is no data transmission, coordinate non-cooperating cognitive user access channel.

It should be noted that, each cognitive user comprises cognitive transmitting node S _twith cognitive receiving node S _r, when primary user is with the cognitive transmitting node of cooperative cognitive user during as via node, transfer of data comprises and 4 types, signalling comprises transmission access request is divided into groups, the grouping of feedback access permission, wherein for the cognitive receiving node of cooperative cognitive user, with for cognitive transmitting node and the cognitive receiving node of non-cooperating cognitive user; When with cognitive receiving node as relaying, as the return of assisting the transmission of mandate business, with corresponding cognitive transmitting node to obtain channel access chance, transfer of data comprises 4 types: and signalling comprises with transmission access request is divided into groups, the grouping of feedback access permission.

It should be noted that, P _tperiodically can carry out the renewal of cooperative cognitive user: if P _tbetter cooperative cognitive user is found, P when initiating renewal process _tnotify that current cooperative cognitive user removes cooperation relation, then according to the cooperative cognitive user that the method choice of step 1 is new and set up contact.

It should be noted that, cooperative cognitive user S ^rcan initiatively remove and P _tcooperation relation, P _tnamely again initiate new cooperative cognitive user selection course according to step 1 after response, choose new cooperative cognitive user

Need to further illustrate, current cooperative cognitive user S ^rbefore releasing cooperation relation, the telecommunication management record of the non-cooperating cognitive user safeguarded sends to P _t; At P _tselected cooperative cognitive user after, by P _tthese information are transmitted to selected after the handing-over completing management data, S ^rexit; broadcast transmission Hello divides into groups, and after the non-cooperating cognitive user in its coverage receives this grouping, adds the self communication record of the numbering of ingress, node maintenance in the acknowledgment packet returned; by the communications records of each non-cooperating cognitive user that receive with from P _tforward and next telecommunication management record compares, the node entries do not had is increased, the nodes records with identical ID is upgraded in management database.

It should be noted that, cooperative cognitive user S in step 4 ^rwhen channel idle being detected and self there is no data transmission, coordinating non-cooperating cognitive user access channel is that described agreement particular content is as follows based on the poor access protocol of request license:

1) each cognitive user safeguards 1 variable represent that the cognitive user number of times sending access request grouping and the access permission that receives divide into groups the difference of number of times; S ^rsafeguard all cognitive user

2) non-cooperating cognitive user i upgrades its variable non-cooperating cognitive user i sends an access request grouping, its variable add 1; Non-cooperating cognitive user i is from S ^rplace's acquisition access permission grouping, its variable subtract 1;

3) cooperative cognitive user S ^rmore new variables as cooperative cognitive user S ^rthe access request received from non-cooperating cognitive user i is divided into groups, then corresponding with this non-cooperating cognitive user i add 1; As cooperative cognitive user S ^rreturn the grouping of access permission to non-cooperating cognitive user i, then corresponding subtract 1;

4) non-cooperating cognitive user i is to cooperative cognitive user S ^rduring request channels, the variable safeguarded be encapsulated in together in access request grouping and send, cooperative cognitive user S ^rby the information received with the information of self maintained compare, if not cooperative cognitive user i reports with S ^rsafeguard corresponding difference exceedes thresholding θ _thtime, cooperative cognitive user S ^rthe request of non-cooperating cognitive user i is refused, and is selected from effectively ask maximum non-cooperating cognitive user, gives this user by current idle time slot allocation.

Beneficial effect of the present invention is:

1, the resource allocation problem of cooperative cognitive node and non-cooperating cognitive nodes can well be solved, and dynamic, the high-efficiency frequency spectrum that realize polytype node when business randomness is stronger are shared;

2, consider the transfer of data of dissimilar user in cooperative cognitive wireless network, and devise a kind of access protocol based on request license difference, ensure that cooperative cognitive user and non-cooperating cognitive user dynamically sharing the communication resource;

3, the impact of dynamic characteristic on system of network topology and communication process is considered, primary user can periodically initiate relay selection process and detect channel, when finding to there is better cooperative cognitive user, then remove cooperation relation with current cooperative cognitive user, and set up with new cooperative cognitive user and contact; Current cooperative cognitive user also initiatively can remove the cooperation relation with primary user, current cooperative cognitive user sends the request removing cooperation relation to primary user, new relay selection process is initiated immediately after primary user's response, when network topology structure and communication process change, good data transmission performance can be ensured by the renewal of cooperative cognitive user like this.

Accompanying drawing explanation

Fig. 1 is implementing procedure schematic diagram of the present invention;

Fig. 2 is that the present invention is using the cognitive transmitting node of cooperative cognitive user as transfer of data during relaying and signalling analysis chart;

Fig. 3 is that the present invention is using the cognitive receiving node of cooperative cognitive user as transfer of data during relaying and signalling analysis chart;

Fig. 4 is the Comparative result figure of the theoretical value that changes with its packet arrival rate of the average waiting delay of primary user of the present invention and analog simulation;

Fig. 5 is the Comparative result figure of the theoretical value that changes with its packet arrival rate of the average waiting delay of cooperative cognitive user of the present invention and analog simulation;

Fig. 6 is the Comparative result figure of the theoretical value that changes with its packet arrival rate of the average waiting delay of non-cooperating cognitive user of the present invention and analog simulation.

Embodiment

Below with reference to accompanying drawing, the invention will be further described, it should be noted that, the present embodiment, premised on the technical program, give detailed implementation step and operating process, but protection scope of the present invention is not limited to the present embodiment.

Operation principle of the present invention:

The present invention is applicable in cooperative cognitive wireless network, comprises a pair primary user and some cognitive user pair, primary user (PU) transmitter P _tits destination node P of potential range _rcomparatively far away, or the link between sending and receiving end is stopped by building and signal experiences deep fading etc., thus cause link-quality to support P _tto P _rdirect communication.During transmission data, PU has limit priority, cooperative cognitive user (CSU) S ^rtake second place, the priority of non-cooperating cognitive user (NCSU) is minimum, and wherein CSU is responsible for the communication coordinating NCSU, and ensures the fairness of NCSU access channel based on the access protocol that request license is poor.Secondly, P _tperiodically can carry out relay selection process, work as P _twhen there is better relaying in discovery, P _tnotify current via node remove cooperation relation, then with new relaying set up contact, current CSU also initiatively can remove the cooperation relation with PU.

As shown in Figure 1, the two-stage center collaboration frequency spectrum shared mechanism based on priority query comprises the following steps:

The first step, chooses CSU.Primary user's transmitter P _tperipherad cognitive user broadcast relay recruits request grouping, and this grouping comprises primary user's receiver P _rinformation.Receive this request and the cognitive user being ready to serve as relaying sends cooperation call request grouping, in its communication range, find P _r.Work as P _rafter receiving the call request from cognitive user (may be multiple), P _rcarry out broadcast response.P can be received _trelaying recruit request and P _rthe cognitive user of response possesses the condition becoming relaying, P _taccording to the Link State relevant with candidate's cooperative cognitive user obtained, the criterion maximum according to end-to-end data rate chooses CSU;

Second step, the transfer of data of PU.At the initial time of each time slot, as long as P _tthere is grouping to arrive, just send immediately.The transmission of grouping is authorized to comprise P _t→ S ^rand S ^r→ P _rin two stages, the sequencing of the two is fixed and recurs, S ^rfor CSU;

3rd step, the transfer of data of CSU.S ^rfirst to P _tgrouping forward, then according to mandate business situation is taken to channel, attempts the transmission of its data;

4th step, the transfer of data of NCSU.NCSU has minimum priority, if S ^rchannel idle detected and oneself also countless according to transmission time, according to based on request license difference access protocol coordinate NCSU access channel;

The described access protocol based on request license difference is as follows: each cognitive user safeguards 1 variable represent that the cognitive user number of times sending access request grouping (ARP) and the access permission that receives divide into groups the difference of (AGP) number of times, this value shows that more greatly the experience of user is poorer.S ^rsafeguard all cognitive user

NCSU upgrades process be: node i sends an ARP, add 1; Node i is from S ^rplace's acquisition AGP, subtract 1.S ^rupgrade rule similar with it, work as S ^rreceive the ARP from node i, then corresponding with this node add 1, work as S ^ran AGP is returned, then to node i subtract 1.In addition, defining node i is to S ^rduring request channels, will encapsulate together and send in arp, S ^rthe information of the information received and self maintained is compared, for reporting of user value and S ^rthe difference of maintenance value exceedes thresholding θ _thuser's request refused, and to select from effective request maximum user, gives this user by current idle time slot allocation.

In the present invention, primary user is as the selection of first order centre management via node, and cooperative cognitive user, as center, the second level, is also responsible for the orderly access of other non-cooperating cognitive user while middle sublicense business.

Cooperative cognitive wireless network of the present invention, comprises a pair primary user P _tand P _r, at primary user's transmitter P _twith primary user's receiver P _rbetween there is not DCL.Each cognitive nodes has unique mark (ID).Communication (comprising signal to send and the reception) radius of all nodes is equal, and follow strict slot synchronization structure, the grouping of node arrives obeys independent Poisson distribution.Slot length is set as a transmission time of dividing into groups, and grouping can only send at time slot section start, and the data packet size of all nodes is identical.Control signal is by independently low-rate channel transmission.All nodes adopt half duplex mode of communication, and topology of networks is relatively stable, and channel has quasistatic feature.At P _tand P _rsome cognitive nodes of overlapping covered interior existence, their meet becomes primary condition of relaying, namely to P _tand P _rall can reach.Fig. 2 is the situation using cognitive transmitting node as relaying, and Fig. 3 is the situation using cognitive receiving node as relaying, and in figure, solid line represents transfer of data, and dotted line represents signalling.

As shown in Figure 2, each cognitive user includes cognitive transmitting node and cognitive receiving node, if with the cognitive transmitting node of CSU as relaying, three circles from left to right represent primary user's transmitter P respectively _t, the cognitive transmitting node of relaying primary user's receiver P _rcommunication range, the communication radius of three is equal.Cognitive user (SU) in region I can detect P _ttransmission, can be used as relaying, this region NCSU launch (as ) can disturb receive from P _tsignal and P _rreceive from interim signal.SU in region II can detect P _ttransmission, and to be positioned at coverage in, the SU in this region launches can be right receive from P _tsignal cause interference.SU in region III is not directly detected P _ttransmission, its communication (as ) can disturb receive P _tinformation and to P _rtransfer authorization data.NCSU in region IV can be right receive from P _tsignal produce interference.P _tas first order center selecting collaboration cognitive user from region II as center, the second level, the non-cooperating cognitive nodes in its overlay area is managed and coordinated, to avoid SU to the interference of authorized communication.

With the cognitive transmitting node of CSU 4 types are comprised as transfer of data during relaying: and wherein for with the cognitive receiving node of corresponding CSU, with for cognitive transmitting node and the cognitive receiving node of non-cooperating cognitive user.As shown in Figure 2, the transfer of data of primary user with for limit priority the transfer of data of cooperative cognitive user priority take second place, be medium priority the transfer of data of non-cooperating cognitive user and priority minimum, be low priority

In fig. 2, signalling comprises NCSU transmission access request grouping ARP and CSU feedback access permission grouping AGP. in the process of transfer primary user business, grouping himself also may be had to arrive.When relaying work complete after, channel is detected, if primary user does not have new data relay requirement, i.e. channel idle, directly can carry out the transmission of its data.In this course, if NCSU is (as S ₁) have grouping to arrive, its cognitive transmitting node (as ) to send ARP.When transmitted in packets terminate, and channel idle detected, simultaneously receive from aRP, to return AGP, S ₁the grouping of oneself is sent at next time slot.

As shown in Figure 3, if with cognitive receiving node as relaying, three circles from left to right represent primary user's transmitter P respectively _t, the cognitive receiving node of relaying primary user's receiver P _rcommunication range, the communication radius of three is equal.Discussion about zones of different is identical with Fig. 2.As the return of assisting the transmission of mandate business, with corresponding cognitive transmitting node to obtain channel access chance, transfer of data comprises 4 types: and similarly, the transfer of data of primary user with for limit priority the transfer of data of cooperative cognitive user priority take second place, be medium priority the transfer of data of non-cooperating cognitive user and priority minimum, be low priority

In figure 3, signalling comprise NCSU and send access request grouping ARP and CSU and feed back access permission grouping AGP. in the process of transfer primary user business, grouping himself also may be had to arrive.When relaying work complete after, channel is detected, if primary user does not have new data relay requirement, i.e. channel idle, and receive from aRP, then cognitive receiving node aGP can be returned notify data can be started send.In this course, if NCSU is (as S ₁) have grouping to arrive, its cognitive transmitting node (as ) to send ARP.When transmitted in packets terminate, and channel idle detected, simultaneously receive from aRP, to return AGP, S ₁the grouping of oneself is sent at next time slot.

In addition, P _tperiodically initiate relay selection process, this duration choose the change depending on channel, for Quick-Change channel, the relaying update cycle should be shorter, to obtain the better transmission performance adapted with channel variation, for becoming channel slowly, the relaying update cycle should be comparatively large, while not losing transmission performance, reduce overhead.Work as P _twhen there is better relaying in discovery, P _tnotify that current via node removes cooperation relation, then with new relaying set up contact.Current CSU also initiatively can remove the cooperation relation with PU, and current CSU needs initiatively to P _tsend the request removing cooperation relation, P _tnew relay selection process is initiated immediately after response.

Along with the renewal of CSU, the NCSU of its management also changes thereupon, therefore specifies current cooperative cognitive user S ^rbefore releasing cooperation relation, the telecommunication management record of the NCSU safeguarded sends to P _t, then by P _tthese information are transmitted to selected after the handing-over completing management data, S ^rexit. broadcast transmission Hello divides into groups, after NCSU in its coverage receives this grouping, in the acknowledgment packet returned, add the self communication record of the numbering of ingress, node maintenance, secondary management Central Radical can realize the information such as justice, the in order access of NCSU according to these records. by the communications records of each NCSU that receive with from P _tforward and next telecommunication management record compares, the node entries do not had is increased, the nodes records with identical ID is upgraded in management database.In order to the management database scale that control CSU safeguards, consider that NCSU may enter or leave the management of secondary centre dynamically simultaneously, a life span can be increased for each user management record, each record upgrades the replacement triggering life span, deletes the record exceeding life span.In order to simply, This document assumes that the personal record that all NCSU report is genuine and believable, namely there is not the NCSU of deception or malice.

By following emulation experiment, effect of the present invention is described further:

Simulated conditions: suppose that the grouping of each cognitive user arrives separate and obeys Poisson distribution, make the packet arrival rate of PU, CSU and NCSU be respectively λ _p, λ _csand λ _ncs.Time slot X _srepresent, and X _s=1/ μ.Ignore the processing delay of node.For PU, its transmitted in packets comprises two stages, all needs the time of 1/ μ, and total service time is 2/ μ.For CSU, when ignoring the frequency spectrum detection time, the service time of each grouping is 1/ μ.For NCSU, its packet service time is also 1/ μ.

Fig. 4 is that the result of the theoretical value that changes with its packet arrival rate of the average waiting delay of PU and analog simulation compares.Average latency E (the W of primary user's grouping _p) comprise the Average Time Remaining E (R of current group (time slot is occupied) or recess (time slot is idle) when grouping enters PU queue _p) sum service time of dividing into groups with other PU waited in queue.Due to using idle for time slot as having a holiday, the length of recess is 1/ μ.

Use represent the average length of PU queue, can obtain:

$E\left(W_p\right)=E\left(R_p\right)+X_p{N}_Q^{\left(1\right)};$

Wherein, X _pfor the service time of PU grouping.Suppose that the channel utilization of primary user is ρ _p, have ρ _p=λ _px _p.Can obtain running into the probability that other PU divides into groups to transmit after PU grouping arrives is 2 λ _p/ μ.

According to Little theorem, average queue length is can calculate:

$E\left(W_p\right)=\frac{\mathrm{\μ}+2{\mathrm{\λ}}_p}{\mathrm{\μ}(\mathrm{\μ}-2{\mathrm{\λ}}_p)};$

Fig. 5 is that the result of the theoretical value that changes with its packet arrival rate of the average waiting delay of CSU and analog simulation compares.Average waiting delay E (the W of CSU grouping _cs) comprise following components: the current Average Time Remaining E (R accepting grouping or the recess of serving _cs), average residual service time of high priority packet in PU queue when CSU grouping arrives with average residual length service time of dividing into groups in CSU queue and CSU is grouped in wait time delay 2 λ that the PU arrived in waiting process divides into groups to bring _pe (W _cs)/μ.Can following formula be obtained:

$E\left(W_{\mathrm{cs}}\right)=E\left(R_{\mathrm{cs}}\right)+\frac{2N_Q^{\left(1\right)}}{\mathrm{\μ}}+\frac{N_Q^{\left(2\right)}}{\mathrm{\μ}}+{\mathrm{\λ}}_p\frac{2E\left(W_{\mathrm{cs}}\right)}{\mathrm{\μ}};$

In above formula with represent PU and CSU queue length respectively.

Utilize Little theorem, easily obtain with e (W _cs) be calculated as follows:

$E\left(W_{\mathrm{cs}}\right)=\frac{\mathrm{\μ}+2{\mathrm{\λ}}_p}{(\mathrm{\μ}-2{\mathrm{\λ}}_p)(\mathrm{\μ}-2{\mathrm{\λ}}_p-{\mathrm{\λ}}_{\mathrm{cs}})};$

Fig. 6 is that the result of the theoretical value that changes with its packet arrival rate of the average waiting delay of NCSU and analog simulation compares.The average latency of NCSU comprises: the current Average Time Remaining E (R accepting grouping or the recess of serving _ncs), the average residual service time of dividing into groups in PU queue when NCSU grouping arrives the average residual service time of dividing into groups in CSU queue with the average residual service time of dividing into groups in NCSU queue and the wait time delay that the high priority packet arrived in NCSU divides into groups waiting process is brought.The average waiting delay expression formula of available NCSU grouping is as follows:

$E\left(W_{\mathrm{ncs}}\right)=E\left(R_{\mathrm{ncs}}\right)+\frac{2N_Q^{\left(1\right)}}{\mathrm{\μ}}+\frac{N_Q^{\left(2\right)}}{\mathrm{\μ}}+\frac{N_Q^{\left(3\right)}}{\mathrm{\μ}}+{\mathrm{\λ}}_p\frac{2E\left(W_{\mathrm{ncs}}\right)}{\mathrm{\μ}}+{\mathrm{\λ}}_s\frac{E\left(W_{\mathrm{ncs}}\right)}{\mathrm{\μ}};$

Wherein, with represent the queue length of PU, CSU and NCSU respectively.Last two of above formula equal sign right-hand member then represents the newly-increased stand-by period that PU and CSU arrived in the NCSU grouping stand-by period divides into groups to cause respectively.

According to Little theorem, $N_Q^{\left(1\right)}={\mathrm{\λ}}_{p}E\left(W_p\right),N_Q^{\left(2\right)}={\mathrm{\λ}}_{\mathrm{cs}}E\left(W_{\mathrm{cs}}\right),N_Q^{\left(3\right)}=\left(\mathrm{\Σ}{\mathrm{\λ}}_{\mathrm{ncs}}\right)E\left(W_{\mathrm{ncs}}\right).$ E (W _ncs) be calculated as follows:

$E\left(W_{\mathrm{ncs}}\right)=\frac{\mathrm{\μ}+2{\mathrm{\λ}}_p}{(\mathrm{\μ}-2{\mathrm{\λ}}_p-{\mathrm{\λ}}_{\mathrm{cs}})(\mathrm{\μ}-2{\mathrm{\λ}}_p-{\mathrm{\λ}}_{\mathrm{cs}}-\mathrm{\Σ}{\mathrm{\λ}}_{\mathrm{ncs}})};$

Can be obtained by Fig. 4, the wait time delay of PU is along with λ _pincrease and increase, because carried mechanism can ensure the limit priority of PU, authorized transmissions by the impact of cognitive business, analog simulation and the calculated results matching accurate.Can be obtained by Fig. 5, the wait time delay of CSU is along with λ _csincrease and increase, theory calculate and simulation results matching accurate.Because primary user has the highest priority, for the Σ λ determined _ncs, the wait time delay of CSU is along with λ _pincrease and increase.Can be obtained by Fig. 6, given λ _pand λ _cs, the wait time delay of NCSU is along with Σ λ _ncsincrease and increase.Because the priority of NCSU is minimum, λ _pand λ _csincreasing all to make NCSU time delay increase, and due to the service time of PU longer (two time slots), improves λ _plarger to the time delay influence of NCSU.

Draw thus, mechanism of carrying can ensure primary user's limit priority, using the access authority of higher priority as the return to cooperative cognitive node, and can when business randomness be stronger, realize dynamically, frequency spectrum share efficiently, therefore the present invention to put forward mechanism be feasible.

For a person skilled in the art, according to above technical scheme and design, various corresponding change and distortion can be provided, and all these change and distortion all should be included within the protection range of the claims in the present invention.

Claims (6)

1. based on a two-stage center collaboration frequency spectrum shared mechanism for priority query, it is characterized in that, described machine-processed process is as follows:

Step 1, selecting collaboration cognitive user, specifically comprises the steps:

Step 1.1, primary user's transmitter P _tperipherad cognitive user broadcast relay recruits request grouping, and this grouping comprises primary user's receiver P _rinformation;

Step 1.2, receives this request and the cognitive user being ready to serve as relaying sends cooperation call request grouping, in its communication range, find P _r;

Step 1.3, works as P _rafter receiving the call request from least one relaying cognitive user, P _rcarry out broadcast response;

Step 1.4, can receive P _trelaying recruit request and P _rthe cognitive user of response possesses the condition of relaying, P _taccording to the Link State relevant with candidate's cooperative cognitive user obtained, according to the criterion selecting collaboration cognitive user that end-to-end data rate is maximum;

Step 2, P _tcarry out transfer of data, mainly comprise P _t→ S ^rand S ^r→ P _rin two stages, the sequencing of the two is fixed and recurs, S ^rfor cooperative cognitive user; At the initial time of each time slot, as long as P _tthere is grouping to arrive, just send data immediately;

Step 3, cooperative cognitive user S ^rcarry out transfer of data, first to P _tgrouping forward, then according to mandate business situation is taken to channel, carries out the transmission of its data;

Step 4, non-cooperating cognitive user carries out transfer of data: as cooperative cognitive user S ^rwhen channel idle being detected and self there is no data transmission, coordinate non-cooperating cognitive user access channel.

2. a kind of two-stage center collaboration frequency spectrum shared mechanism based on priority query according to claim 1, it is characterized in that, each cognitive user comprises cognitive transmitting node S _twith cognitive receiving node S _r, when primary user is with the cognitive transmitting node of cooperative cognitive user during as via node, transfer of data comprises and 4 types, signalling comprises transmission access request is divided into groups, the grouping of feedback access permission; Wherein for the cognitive receiving node of cooperative cognitive user, with for cognitive transmitting node and the cognitive receiving node of non-cooperating cognitive user; When with cognitive receiving node as relaying, as the return of assisting the transmission of mandate business, with corresponding cognitive transmitting node to obtain channel access chance, transfer of data comprises 4 types: and signalling comprises with transmission access request is divided into groups, the grouping of feedback access permission.

3. a kind of two-stage center collaboration frequency spectrum shared mechanism based on priority query according to claim 1, is characterized in that, P _tperiodically can carry out the renewal of cooperative cognitive user: if P _tbetter cooperative cognitive user is found, P when initiating renewal process _tnotify that current cooperative cognitive user removes cooperation relation, then according to the cooperative cognitive user that the method choice of step 1 is new and set up contact.

4. a kind of two-stage center collaboration frequency spectrum shared mechanism based on priority query according to claim 1, is characterized in that, cooperative cognitive user S ^rcan initiatively remove and P _tcooperation relation, P _tnamely again initiate new cooperative cognitive user selection course according to step 1 after response, choose new cooperative cognitive user

5. a kind of two-stage center collaboration frequency spectrum shared mechanism based on priority query according to claim 3 or 4, is characterized in that, current cooperative cognitive user S ^rbefore releasing cooperation relation, the telecommunication management record of the non-cooperating cognitive user safeguarded sends to P _t; At P _tselected cooperative cognitive user after, by P _tthese information are transmitted to selected after the handing-over completing management data, S ^rexit; broadcast transmission Hello divides into groups, and after the non-cooperating cognitive user in its coverage receives this grouping, adds the self communication record of the numbering of ingress, node maintenance in the acknowledgment packet returned; by the communications records of each non-cooperating cognitive user that receive with from P _tforward and next telecommunication management record compares, the node entries do not had is increased, the nodes records with identical ID is upgraded in management database.

6. a kind of two-stage center collaboration frequency spectrum shared mechanism based on priority query according to claim 1, is characterized in that, cooperative cognitive user S in step 4 ^rwhen channel idle being detected and self there is no data transmission, coordinating non-cooperating cognitive user access channel is that described agreement particular content is as follows based on the poor access protocol of request license:

1) each cognitive user safeguards 1 variable represent that the cognitive user number of times sending access request grouping and the access permission that receives divide into groups the difference of number of times; S ^rsafeguard all cognitive user

2) non-cooperating cognitive user i upgrades its variable non-cooperating cognitive user i sends an access request grouping, its variable add 1; Non-cooperating cognitive user i is from S ^rplace's acquisition access permission grouping, its variable subtract 1;

3) cooperative cognitive user S ^rmore new variables : as cooperative cognitive user S ^rthe access request received from non-cooperating cognitive user i is divided into groups, then corresponding with this non-cooperating cognitive user i add 1; As cooperative cognitive user S ^rreturn the grouping of access permission to non-cooperating cognitive user i, then corresponding subtract 1;

4) non-cooperating cognitive user i is to cooperative cognitive user S ^rduring request channels, the variable safeguarded be encapsulated in together in access request grouping and send, cooperative cognitive user S ^rby the information received with the information of self maintained compare, if not cooperative cognitive user i reports with S ^rsafeguard corresponding difference exceedes thresholding θ _thtime, cooperative cognitive user S ^rthe request of non-cooperating cognitive user i is refused, and is selected from effectively ask maximum non-cooperating cognitive user, gives this user by current idle time slot allocation.