CN104010313A - Cooperation interference-resistant frequency spectrum access method based on Nash game theory - Google Patents

Abstract

A cooperation interference-resistant frequency spectrum access method based on the Nash game theory comprises the following steps that (1) a cognitive user has access to a frequency spectrum of an authorized user in a cooperation mode, and after receiving the information of the authorized user, the cognitive user helps send the information of the authorized user to an authorized receiving end in a decoding forwarding cooperation mode; (2) the speed RP obtained after the authorized user is helped and cooperated by the cognitive user and the speed RD in the direct sending process of the authorized user are calculated; (3) if RP>=RD, the authorized user will share some time with the cognitive user and authorizes the cognitive user to have access to the frequency spectrum of the authorized user, and after the cognitive user has access to the frequency spectrum of the authorized user, the cognitive user forwards the information of the authorized user through part of bandwidth, and sends the information of the cognitive user through the residual bandwidth; if RP<RD, the authorized user will not authorize the cognitive user to have access to the frequency spectrum of the authorized user and continues to directly send the information of the authorized user. The cooperation interference-resistant frequency spectrum access method based on the Nash game theory effectively eliminates the problem of mutual interference of the authorized user and the cognitive user, and improves user performance.

Description

A kind of based on receiving the anti-interference frequency spectrum access method of cooperation of assorted game

Technical field

The invention belongs to the cognition wireless technical field of telecommunications in wireless communication field, especially a kind of frequency spectrum access method.

Background technology

Along with the development of wireless communication technology, in future broadband wireless communication systems, it is more and more that wireless communication user becomes, and people are the growth of explosion type to the application and service of radio communication simultaneously.But the frequency spectrum resource that can be used by wireless communication system is limited, and most of frequency range has been assigned to authorized user, makes these new application and service not have frequency spectrum to use.But according to the research report of frequency spectrum policy taskforce of FCC, the utilance of existing mandate frequency spectrum only has 15%～85%, these frequency spectrums of distributing to authorized user are not all fully utilized on time and space.It is visible that to cause the main cause that frequency spectrum resource is in short supply be spectrum management mode and the spectrum allocation may strategy of existing this static state.Cognitive radio is by self-adapting detecting wireless environment around, real-time regulating system parameter (as modulation technique, operating frequency and through-put power etc.), ensureing under the impregnable prerequisite of proper communication of authorized user, wait for an opportunity insertion authority frequency spectrum, thereby make full use of limited frequency spectrum resource, promote the utilance of frequency spectrum resource.

Coexist in formula frequency spectrum access method at cognitive radio, cognitive user, by the transmitted power drawing oneself up, is not affecting under the prerequisite of authorized user proper communication, insertion authority user's frequency spectrum, and authorized user communicates simultaneously.But in this frequency spectrum access method, use identical frequency spectrum to communicate owing to being familiar with user and authorized user simultaneously, between them, exist and disturb all the time, make to be originally not fully utilized with regard to very limited frequency spectrum resource, the performance of authorized user and cognitive user also can be because interference is affected.

Summary of the invention

In order to overcome in the existing formula frequency spectrum access method that coexists problem and the limited deficiency of user performance of phase mutual interference between authorized user and cognitive user, the invention provides phase mutual interference between a kind of effective elimination authorized user and cognitive user problem, promote user performance based on receiving the anti-interference frequency spectrum access method of cooperation of assorted game.

The technical solution adopted for the present invention to solve the technical problems is:

A kind of based on receiving the anti-interference frequency spectrum access method of cooperation of assorted game, radio communications system comprises a main system and a cognitive system, wherein, main system is by an authorized user transmitting terminal and authorize receiving terminal to form, described main system is supported relay function, the mandate frequency spectrum being made up of one section of W bandwidth; Cognitive system is made up of a cognitive user transmitting terminal and cognitive receiving terminal, and described cognitive system can be simulated radio protocol and the system parameters in main system; The anti-interference frequency spectrum access method of described cooperation comprises following process:

1) cognitive user is with cooperation mode insertion authority user's frequency spectrum, and cognitive user receives after the information of authorized user, helps the information that sends authorized user to authorizing receiving terminal by decoding forward collaboration mode;

2) calculating authorized user is cooperated and is helped the rear speed R obtaining by cognitive user _pspeed R while direct transferring with authorized user _d;

3) if R _p>=R _d, authorized user will distribute portion of time to understanding user, authorizes its frequency spectrum that accesses oneself, after cognitive user insertion authority user's frequency spectrum, utilizes a part of bandwidth to forward the information of authorized user, utilizes remaining bandwidth to send the information of oneself;

Time between authorized user and cognitive user and allocated bandwidth problem are modeled as one and receive assorted problem of game, suc as formula (1):

$\begin{array}{cc}(t^{*},b^{*})=\arg \underset{U_i>{\stackrel{\&OverBar;}{U}}_i}{\max }(U_P-{\stackrel{\&OverBar;}{U}}_P)(U_S-{\stackrel{\&OverBar;}{U}}_S)& i=(P,S)---\left(1\right)\end{array}$

Wherein, t ^*and b ^*represent respectively optimal time and allocated bandwidth, U _pand U _srepresent respectively after cognitive user insertion authority user frequency spectrum the speed that the speed that authorized user obtains and cognitive user obtain

Rate, is expressed as:

U _P＝min{tR ₂,(1-t)bR ₃+tR _D} (2)

U _S＝(1-t)(1-b)R ₄＝(1-t-b+tb)R ₄ (3)

Wherein, t represents that first time slot authorized user sends the shared time of own information, and b is illustrated in the user aid of second time slot understanding and forwards the shared bandwidth of authorization user information, and the span of t and b is 0～1, R _dspeed while direct transferring for authorized user, $R_2={W\log }_2(1+\frac{P_P{\mathrm{\&gamma;}}_2}{N_0}),R_3={W\log }_2(1+\frac{P_S{\mathrm{\&gamma;}}_3}{{2N}_0}),R_4={W\log }_2(1+\frac{P_S{\mathrm{\&gamma;}}_4}{{2N}_0}),$ P _pand P _sbe respectively the transmitting power of authorized user and cognitive user, γ ₁, γ ₂, γ ₃and γ ₄be respectively authorized user transmitting terminal to authorizing receiving terminal, authorized user transmitting terminal is to cognitive user transmitting terminal, and cognitive user transmitting terminal is to the channel gain of authorizing receiving terminal and cognitive user transmitting terminal to cognitive receiving terminal link, N ₀for noise power spectral density; Formula (1), represent respectively the minimum-rate requirement of authorized user and cognitive user,

Obtain above-mentioned optimal time t by receiving assorted game method ^*with allocated bandwidth b ^*:

Work as bR ₃-R _d-R ₂when < 0,

$t^{*}=\frac{R_2{R}_3{R}_4+R_D{R}_4(R_2+R_3-R_D)}{2R_2{R}_4(R_2+R_3-R_D)}---\left(4\right)$

$b^{*}=\frac{{4R}_2{R}_4(R_2+R_3-R_D)}{(R_2+R_3-R_D)({2R}_2{R}_4-R_D{R}_4)-R_2{R}_3{R}_4}---\left(5\right)$

Work as bR ₃-R _d-R ₂>=0 o'clock,

$t^{*}=\frac{R_D+R_2}{{2R}_2}---\left(6\right)$

$b^{*}=\frac{R_D+R_2}{R_3}---\left(7\right);$

If R _p< R _d, authorized user can not authorized the frequency spectrum of cognitive user access oneself, continues to send by direct transferring the information of oneself.

Further, described step 2) in, cognitive user is by two time slot decoding forward collaboration mode insertion authority users' frequency spectrum;

At first time slot, holding time t, authorized user transmitting terminal sends information to authorizing receiving terminal and cognitive user transmitting terminal by whole W bandwidth, so authorized user transmitting terminal is to the speed of cognitive user transmitting terminal link be expressed as:

$R_p^1=\mathrm{tW}{\log }_2(1+\frac{P_p{\mathrm{\&gamma;}}_2}{N_0})---\left(8\right)$

At second time slot, holding time 1-t, cognitive user transmitting terminal helps the information of the authorized user transmitting terminal of decoding to send to mandate receiving terminal by bW bandwidth, so cognitive user transmitting terminal is to the speed of authorizing receiving terminal link be expressed as:

$R_P^2=(1-t)\mathrm{bW}{\log }_2(1+\frac{P_S{\mathrm{\&gamma;}}_3}{{2N}_0})+t{W\log }_2(1+\frac{P_P{\mathrm{\&gamma;}}_1}{N_0})---\left(9\right)$

So the speed that authorized user obtains under the help of cognitive user by two time slots is to be expressed as:

$R_P=\min \{R_P^1,R_P^2\}---\left(10\right)$

Meanwhile, W bandwidth that cognitive user is utilized remaining (1-b) sends the information of oneself, so the speed R that cognitive user obtains _sbe expressed as:

$R_S=(1-t)(1-b){W\log }_2(1+\frac{P_S{\mathrm{\&gamma;}}_4}{2N_0})---\left(11\right).$

Technical conceive of the present invention is: owing to coexisting in formula frequency spectrum access method, cognitive user and authorized user use identical frequency spectrum to communicate simultaneously, mutually, exist and disturb all the time, make to be originally not fully utilized with regard to very limited frequency spectrum resource, the performance of authorized user and cognitive user also can be because interference is affected.In this patent method, cognitive user is by the mode insertion authority user's of cooperation frequency spectrum, and authorized user and cognitive user are carried out transmission information by different time and bandwidth respectively, can effectively solve the interference problem between authorized user and cognitive user.

Beneficial effect of the present invention is mainly manifested in: (1) has eliminated the interference problem of authorized user and cognitive user in the formula frequency spectrum access method that coexists; (2) promoted the performance of authorized user and cognitive user.

Brief description of the drawings

Fig. 1 is the anti-interference frequency spectrum access model schematic diagram of the inventive method, wherein, and d ₁for authorized user transmitting terminal is to the distance of authorizing receiving terminal, d ₂for authorized user transmitting terminal is to the Recognition distance user transmitting terminal of authorizing receiving terminal, d ₃for cognitive user transmitting terminal is to the distance of authorizing receiving terminal, d ₄for cognitive user transmitting terminal is to the Recognition distance user transmitting terminal of cognitive receiving terminal;

Fig. 2 is that time t and the bandwidth b of the inventive method distributes along with d ₃variation diagram;

Fig. 3 is that the speed of authorized user and cognitive user is along with d ₃variation diagram;

Fig. 4 adopts method of the present invention to be assigned as 1/2 o'clock method with the employing time to compare along with d ₃variation diagram.

Embodiment

Below in conjunction with accompanying drawing, the invention will be further described.

With reference to Fig. 1～Fig. 4, a kind of based on receiving the anti-interference frequency spectrum access method of cooperation of assorted game, realize based on existing radio communications system, described radio communications system comprises a main system and a cognitive system, wherein main system is by an authorized user transmitting terminal (primary transmitter, PT) and authorize receiving terminal (primary receiver, PR) composition.Main system is supported relay function, the mandate frequency spectrum being made up of one section of W bandwidth.Cognitive system is made up of a cognitive user transmitting terminal (cognitive transmitter, CT) and cognitive receiving terminal (cognitive receiver, CR).Cognitive system can be simulated radio protocol and the system parameters in main system.

In the method for present embodiment, cognitive user is with cooperation mode insertion authority user's frequency spectrum.Cognitive user receives after the information of authorized user, helps the information that sends authorized user to authorizing receiving terminal by decoding forward collaboration mode.If authorized user is cooperated and is helped the rear speed R obtaining by cognitive user _pbe more than or equal to the speed R while oneself direct transferring _d, i.e. R _p>=R _d, authorized user will distribute portion of time to understanding user, authorizes it to access the frequency spectrum of oneself.After cognitive user insertion authority user's frequency spectrum, utilize a part of bandwidth to forward the information of authorized user, help it to improve performance, utilize remaining bandwidth to send the information of oneself.Otherwise, if R _p< R _d, authorized user can not authorized the frequency spectrum of cognitive user access oneself, continues to send by direct transferring the information of oneself.

In present embodiment, authorized user is cooperated and is helped the rear speed R obtaining by cognitive user _pspeed R when direct transferring _dcan obtain by the following method:

Cognitive user is by two time slot decoding forward collaboration mode insertion authority users' frequency spectrum.At first time slot, holding time t, PT sends information to PR and CT by whole W bandwidth.So the speed of PT → CT link can be expressed as:

$R_p^1=\mathrm{tW}{\log }_2(1+\frac{P_p{\mathrm{\&gamma;}}_2}{N_0})---\left(8\right)$

Wherein γ ₂for PT is to the channel gain of CT link, N ₀for noise power spectral density.

At second time slot, holding time 1-t, CT helps the information of the PT of decoding to send to PR by bW bandwidth, so the speed of CT → PR link can be expressed as:

$R_P^2=(1-t)\mathrm{bW}{\log }_2(1+\frac{P_S{\mathrm{\&gamma;}}_3}{{2N}_0})+t{W\log }_2(1+\frac{P_P{\mathrm{\&gamma;}}_1}{N_0})---\left(9\right)$

Wherein P _sfor the transmitting power of via node, γ ₃for CT is to the channel gain of PR link.So the speed that authorized user obtains under the help of cognitive user by two time slots can be expressed as:

$R_P=\min \{R_P^1,R_P^2\}---\left(10\right)$

Meanwhile, W bandwidth that cognitive user is utilized remaining (1-b) sends the information of oneself, so the obtainable speed of cognitive user can be expressed as:

$R_S=(1-t)(1-b){W\log }_2(1+\frac{P_S{\mathrm{\&gamma;}}_4}{2N_0})---\left(11\right).$

Wherein γ ₄for CT is to the channel gain of CR link.

Speed R when authorized user direct transfers _dcan be expressed as:

$R_D={W\log }_2(1+\frac{P_P{\mathrm{\&gamma;}}_1}{N_0})---\left(12\right)$

Wherein P _pfor the transmitting power of authorized user, γ ₁for PT is to the channel gain of PR link.

Time and bandwidth allocation methods in present embodiment are specially:

Time between authorized user and cognitive user and allocated bandwidth problem can be modeled as one and receive assorted problem of game, suc as formula (1):

$\begin{array}{cc}(t^{*},b^{*})=\arg \underset{U_i>{\stackrel{\&OverBar;}{U}}_i}{\max }(U_P-{\stackrel{\&OverBar;}{U}}_P)(U_S-{\stackrel{\&OverBar;}{U}}_S)& i=(P,S)---\left(1\right)\end{array}$

Wherein, t ^*and b ^*represent respectively optimal time and allocated bandwidth, U _pand U _srepresent respectively after cognitive user insertion authority user frequency spectrum, the speed that the speed that authorized user obtains and cognitive user obtain, is expressed as:

U _P＝min{tR ₂,(1-t)bR ₃+tR _D} (2)

U _S＝(1-t)(1-b)R ₄＝(1-t-b+tb)R ₄ (3)

Wherein, t represents that first time slot authorized user sends the shared time of own information, and b is illustrated in the user aid of second time slot understanding and forwards the shared bandwidth of authorization user information, and the span of t and b is 0～1, $R_2=W{\log }_2(1+\frac{P_P{\mathrm{\&gamma;}}_2}{N_0}),R_3{W\log }_2(1+\frac{P_S{\mathrm{\&gamma;}}_3}{{2N}_0}),$ formula (1), represent respectively the minimum-rate requirement of authorized user and cognitive user, ${\stackrel{\&OverBar;}{U}}_P=R_D,{\stackrel{\&OverBar;}{U}}_S=0;$

Obtain above-mentioned optimal time t by receiving assorted game method ^*with allocated bandwidth b ^*:

Work as bR ₃-R _d-R ₂when < 0,

$t^{*}=\frac{R_2{R}_3{R}_4+R_D{R}_4(R_2+R_3-R_D)}{2R_2{R}_4(R_2+R_3-R_D)}---\left(4\right)$

$b^{*}=\frac{{4R}_2{R}_4(R_2+R_3-R_D)}{(R_2+R_3-R_D)({2R}_2{R}_4-R_D{R}_4)-R_2{R}_3{R}_4}---\left(5\right)$

Work as bR ₃-R _d-R ₂>=0 o'clock,

$t^{*}=\frac{R_D+R_2}{{2R}_2}---\left(6\right)$

$b^{*}=\frac{R_D+R_2}{R_3}---\left(7\right);$

The present embodiment based on receiving the anti-interference frequency spectrum access method of cooperation of assorted game, can effectively eliminate the interference problem of authorized user and cognitive user in the formula frequency spectrum access method that coexists.

In the frequency spectrum access method of this enforcement, cognitive user licenses to its second time slot, holding time 1-t, insertion authority user's frequency spectrum at authorized user.The bW bandwidth that cognitive user utilizes part access to obtain helps to forward the information of authorized user, utilizes remaining (1-b) W bandwidth to send the information of oneself.Authorized user and cognitive user send information by different time and bandwidth respectively, can not produce interference between mutually.In the present embodiment, suppose PT, PR, CT and CR are in X-axis, and wherein PT and PR are in (1,0) and (0,0).CT moves in X positive axis, and CR is in the centre of PR and CT.So d ₁=1, d ₂=| 1-d ₃|, d ₄=1/2d ₂.γ _i=| (d _i) ^v| ², i=(1,2,3,4), path attenuation index v=3.P _p/ N ₀=P _s/ N ₀=10dB, system bandwidth is W=1MHz.Optimal time and the allocated bandwidth of intermediate frequency spectrum cut-in method of the present invention in Fig. 2, are shown.

The frequency spectrum access method of the present embodiment has promoted the performance of authorized user and cognitive user.In Fig. 3, shown the speed that adopts authorized user and cognitive user after frequency spectrum access method of the present invention, can find out and adopt after frequency spectrum access method of the present invention, not only cognitive user can obtain frequency spectrum access, and the performance of authorized user also can get a promotion.As shown in Figure 4, the performance of this method will obviously be better than being assigned as 1/2 method when the time, and the scope of the accessible authorized user frequency spectrum of this method cognitive user will be far longer than the time and be assigned as 1/2 method, has effectively promoted the utilance of frequency spectrum resource.

Claims (2)

1. one kind based on receiving the anti-interference frequency spectrum access method of cooperation of assorted game, radio communications system comprises a main system and a cognitive system, wherein, main system is by an authorized user transmitting terminal and authorize receiving terminal to form, described main system is supported relay function, the mandate frequency spectrum being made up of one section of W bandwidth; Cognitive system is made up of a cognitive user transmitting terminal and cognitive receiving terminal, and described cognitive system can be simulated radio protocol and the system parameters in main system; It is characterized in that: the anti-interference frequency spectrum access method of described cooperation comprises following process:

1) cognitive user is with cooperation mode insertion authority user's frequency spectrum, and cognitive user receives after the information of authorized user, helps the information that sends authorized user to authorizing receiving terminal by decoding forward collaboration mode;

2) calculating authorized user is cooperated and is helped the rear speed R obtaining by cognitive user _pspeed R while direct transferring with authorized user _d;

3) if R _p>=R _d, authorized user will distribute portion of time to understanding user, authorizes its frequency spectrum that accesses oneself, after cognitive user insertion authority user's frequency spectrum, utilizes a part of bandwidth to forward the information of authorized user, utilizes remaining bandwidth to send the information of oneself;

Time between authorized user and cognitive user and allocated bandwidth problem are modeled as one and receive assorted problem of game, suc as formula (1):

$\begin{array}{cc}(t^{*},b^{*})=\arg \underset{U_i>{\stackrel{\&OverBar;}{U}}_i}{\max }(U_P-{\stackrel{\&OverBar;}{U}}_P)(U_S-{\stackrel{\&OverBar;}{U}}_S)& i=(P,S)---\left(1\right)\end{array}$

Wherein, t ^*and b ^*represent respectively optimal time and allocated bandwidth, U _pand U _srepresent respectively after cognitive user insertion authority user frequency spectrum, the speed that the speed that authorized user obtains and cognitive user obtain, is expressed as:

U _P＝min{tR ₂,(1-t)bR ₃+tR _D} (2)

U _S＝(1-t)(1-b)R ₄＝(1-t-b+tb)R ₄ (3)

Wherein, t represents that first time slot authorized user sends the shared time of own information, and b is illustrated in the user aid of second time slot understanding and forwards the shared bandwidth of authorization user information, and the span of t and b is 0～1, R _dspeed while direct transferring for authorized user, $R_2={W\log }_2(1+\frac{P_P{\mathrm{\&gamma;}}_2}{N_0}),R_3={W\log }_2(1+\frac{P_S{\mathrm{\&gamma;}}_3}{{2N}_0}),R_4={W\log }_2(1+\frac{P_S{\mathrm{\&gamma;}}_4}{{2N}_0}),$ P _pand P _sbe respectively the transmitting power of authorized user and cognitive user, γ ₁, γ ₂, γ ₃and γ ₄be respectively authorized user transmitting terminal to authorizing receiving terminal, authorized user transmitting terminal is to cognitive user transmitting terminal, and cognitive user transmitting terminal is to the channel gain of authorizing receiving terminal and cognitive user transmitting terminal to cognitive receiving terminal link, N ₀for noise power spectral density; Formula (1), represent respectively the minimum-rate requirement of authorized user and cognitive user,

Obtain above-mentioned optimal time t by receiving assorted game method ^*with allocated bandwidth b ^*:

Work as bR ₃-R _d-R ₂when < 0,

$t^{*}=\frac{R_2{R}_3{R}_4+R_D{R}_4(R_2+R_3-R_D)}{2R_2{R}_4(R_2+R_3-R_D)}---\left(4\right)$

$b^{*}=\frac{{4R}_2{R}_4(R_2+R_3-R_D)}{(R_2+R_3-R_D)({2R}_2{R}_4-R_D{R}_4)-R_2{R}_3{R}_4}---\left(5\right)$

Work as bR ₃-R _d-R ₂>=0 o'clock,

$t^{*}=\frac{R_D+R_2}{{2R}_2}---\left(6\right)$

$b^{*}=\frac{R_D+R_2}{R_3}---\left(7\right);$

If R _p< R _d, authorized user can not authorized the frequency spectrum of cognitive user access oneself, continues to send by direct transferring the information of oneself.

2. as claimed in claim 1 based on receiving the anti-interference frequency spectrum access method of cooperation of assorted game, it is characterized in that: described step 2) in, cognitive user is by two time slot decoding forward collaboration mode insertion authority users' frequency spectrum;

At first time slot, holding time t, authorized user transmitting terminal sends information to authorizing receiving terminal and cognitive user transmitting terminal by whole W bandwidth, so authorized user transmitting terminal is to the speed of cognitive user transmitting terminal link be expressed as:

$R_p^1=\mathrm{tW}{\log }_2(1+\frac{P_p{\mathrm{\&gamma;}}_2}{N_0})---\left(8\right)$

At second time slot, holding time 1-t, cognitive user transmitting terminal helps the information of the authorized user transmitting terminal of decoding to send to mandate receiving terminal by bW bandwidth, so cognitive user transmitting terminal is to the speed of authorizing receiving terminal link be expressed as:

$R_P^2=(1-t)\mathrm{bW}{\log }_2(1+\frac{P_S{\mathrm{\&gamma;}}_3}{{2N}_0})+t{W\log }_2(1+\frac{P_P{\mathrm{\&gamma;}}_1}{N_0})---\left(9\right)$

So the rate representation that authorized user obtains under the help of cognitive user by two time slots is:

$R_P=\min \{R_P^1,R_P^2\}---\left(10\right)$

Meanwhile, W bandwidth that cognitive user is utilized remaining (1-b) sends the information of oneself, so the speed R that cognitive user obtains _sbe expressed as:

$R_S=(1-t)(1-b){W\log }_2(1+\frac{P_S{\mathrm{\&gamma;}}_4}{2N_0})---\left(11\right).$