CN102833759A - Cognitive radio spectrum allocation method enabling OFDM (orthogonal frequency division multiplexing) master user to realize maximum revenue - Google Patents

Abstract

The invention discloses a cognitive radio spectrum allocation method enabling an OFDM (orthogonal frequency division multiplexing) master user to realize maximum revenue and belongs to the field related to cognitive radio spectrum resource management in wireless communication. The method is characterized in that the master user serving as a manager of spectrum is used for information interaction with a secondary user, taking specificity of the OFDM multi-carrier technology into consideration, inter-carrier interferences and requirements on error rate of users are both taken into consideration during establishment of a target function, and rational spectrum price and access regulations are designed to standardize the system operational process. By the cognitive radio spectrum allocation method enabling the OFDM master user to realize the maximum revenue, real-time selection of using spectrum of the secondary user in spectrum market of multiple secondary users can be realized by the master user, so that revenue of the master user can be increased.

Description

Make the cognitive radio frequency spectrum distribution method of OFDM master user maximize revenue

Technical field

The present invention relates to a kind of cognitive radio frequency spectrum distribution method, belong to cognitive radio frequency spectrum resource management association area in the radio communication based on the main user's maximize revenue of making of OFDM.

Technical background

Cognitive radio (Cognitive Radio) is a kind of frequency spectrum share technology of intelligence; It can rely on the support of artificial intelligence; The extraneous wireless communications environment of perception; According to certain study and decision making algorithm, real-time adaptive ground changes system operational parameters (like through-put power, carrier frequency, modulation system), allows on time, space and frequency, to carry out the spectrum reuse of multidimensional in theory; Thereby greatly reduce the constraint of the restriction of frequency spectrum and bandwidth, foretold to be the most popular following wireless technology the wireless technology development.OFDM proposes beginning just because its flexibility and adaptivity are considered to the optimal selection of cognitive radio transmission technology as one of hot technology of realizing the high-speed radio transmission in the cognitive radio notion.

Because the idling-resource frequency spectrum is limited; Need competition to use frequency spectrum resource between the inferior user; And different inferior users' priority, qos requirement maybe be different; The main purpose of spectrum allocation may is exactly according to time different spectrum requirement of user, fairly distributes the frequency spectrum resource of some effectively, makes systematic function improve or approaches optimum state.The cognitive radio frequency spectrum method of salary distribution of primary and secondary user's cooperation formula can exchange and effectively avoid interference through the little information between the user, guarantees data transmission quality.

In real-time frequency spectrum trade market, main user has the right from the process of selling own idle frequency spectrum, to obtain income, and through formulating corresponding frequency spectrum " lease " rule, makes interests in long-term frequency spectrum use, reach maximization.Cognitive radio system based on main user's own behavior; To drive with the individual interests of user is starting point; Research with main user under the different condition and time user behavior is foundation, inserts laws and decrees assurance user income with rationally perfect cognitive radio frequency spectrum and coordinates mutually not conflict, and give full play to the independence of user behavior decision-making; Main user need make the optimizing decision of spectrum allocation may rapidly on each time slot; Promptly under the constraints of wireless environment, frequency spectrum policy, interference-limited, from a plurality of potential inferior users, select the limited user who adapts with idle frequency spectrum quantity, allow it to insert and use idle frequency spectrum.In cognitive radio system,, therefore need phase mutual interference between suppressed carrier because the signal of different sub carrier from different users, is difficult to guarantee the consistent or accurate quadrature of parameter of signal.Secondly, also will consider the influence of time user's error rate demand and channel fading factor, and comprehensively each factor is improved to model, guaranteed to reach maximum throughput when time the user does not cause interference to neighboring user system.

Ceaselessly fruit machine (Restless Bandits) is the theory of a series of sequential decision problems at random of research.Finger makes a policy on series of discrete or continuous moment point, and system is obtaining and the state of living in and the relevant repayment of taking to make a strategic decision, and the system that influences is at the residing state of next one decision-making moment point, and influences following finally benefited with this.It can solve through the priority index value (priority-index) of each project, and index value can relax (Linear Programming Relaxation) through linear programming and original duplicate key exploratory method (Primal-dual Index Heuristic) is tried to achieve.The priority index value can and be stored in the concordance list (index table) in off-line (off-line) state computation, thereby can reduce online (on-line) operand significantly and implement complexity.List of references P.Whittle; " Restless bandits:Activity allocation in a changing world " .A Celebration of Applied Probability.1988 (25): 287-298; With D.Berstimas and J.Ni～no-Mora. " Restless bandits; linear programming relaxations, and a primal dual index heuristic " .Operations Research.2000,48 (1): 80-90.

Summary of the invention

Main purpose of the present invention is on main user's angle, considers the situation that a plurality of users compete limited frequency spectrum resource, is target with main user's maximize revenue, makes up the real-time cognitive radio frequency spectrum distribution system based on OFDM.Solve in the real time spectrum market repeatedly the decision problem under the user situation, and improve main user's income through the behaviour decision making of optimizing main user.

The present invention the cognitive radio networks scene that should adapt to see Fig. 1.

System's running schematic diagram in the technical scheme of the present invention is seen Fig. 2.

The technical scheme that makes the cognitive radio frequency spectrum distribution method of OFDM master user maximize revenue is on PC, to realize by following flow process:

Step (1); The use solicited message that at least one potential inferior user base station is sent idle frequency spectrum to a main user base station; Wherein comprise at least: buffer data size separately, average data arrival rate λ, geographical position and error rate demand, said user base station and main user base station are designated hereinafter simply as time user and main user;

Step (2), the frequency spectrum that main user collects each said user according to the following steps uses request:

Step (2.1); At time slot t; Main user is the inferior User Status set that state is set up a t time slot with the metadata cache amount of each said user under time slot t; Be called for short the system mode vector, expression with

:

S _gThe expression state is the inferior user of g, and state is used S _g(t) expression,

S ₀(t) the expression buffer data size is 0, increase progressively successively,

S _G(t) expression desired data buffer memory has surpassed the storage capacity of this time user data cache amount, and press for the frequency band transmission data and run well guaranteeing, other main user network just ready about,

G+1 is the state sum,

Step (2.2), corresponding to inferior user's different conditions, main user is provided with every Mb data traffic price and state price, and along with state increases progressively, the state price increases progressively by the equivalent of setting, thereby sets up following T time slot total revenue R:

$R=\underset{t=0}{\overset{T-1}{\mathrm{\Σ}}}(R_v^a\left(t\right)+R_s^a\left(t\right)),$

is time slot t unit data flow price; It is set point; Be time-varying

is time slot t state price; It is set point; Be time-varying

The behavioral unity of above-mentioned two kinds of prices that inferior user is taken place is expressed as

a _n(t)=1 expression time user carries out transfer of data, a at the idle frequency spectrum that time slot t takies main user _n(t)=0 expression time user does not take main user's idle frequency spectrum,

Step (2.3), main user is called for short SLP with the frequency spectrum Tenancy Agreement Spectrum Lease Protocol that the above-mentioned information in the step (2.2) forms a short-term, is broadcast to all said potential users in its coverage;

Step (3), main user carries out the frequency spectrum lease according to the following steps and prepares:

Step (3.1) if said time potential user do not accept the frequency spectrum Tenancy Agreement SLP that main user is provided with in step (2.3), then turns to the network at other main user place, if accept, then sends and accepts message to said main user,

Step (3.2), main user calculates the preferential index value table of a selected M idle frequency band from the individual inferior user of N according to inferior number of users N that accepts said frequency spectrum Tenancy Agreement and main user M idle frequency band when the time slot t, M≤N, step is following:

Step (3.2.1), the state transition probability matrix

the when behavior that main user calculates time user n according to the following steps is a

wherein:

p _EEFor t user n of current time slots buffer data size is continuously 0 probability,

p _BKFor t user n of current time slots reduces the probability of again getting back to current main user network because of buffer data size because of buffer data size surpasses after the buffer memory threshold value turns to other main user network, be the estimated value of setting,

p _OTFor t user n of current time slots turns to behind other main user network still the not probability in current main user network, be the estimated value of setting,

p _OT+p _BK=1，

Inferior user n is not inserting at idle frequency spectrum a (t)=0 o'clock, and the probability

that forwards state g ' from state g to is expressed as:

$P_{{\mathrm{gg}}^{\′}}^0=P\{({\mathrm{\ϵ}}_{g^{\′}-1}-\left(\frac{{\mathrm{\ϵ}}_g+{\mathrm{\ϵ}}_{g-1}}{2}\right))\≤X\≤({\mathrm{\ϵ}}_{g^{\′}}-\left(\frac{{\mathrm{\ϵ}}_g+{\mathrm{\ϵ}}_{g-1}}{2}\right))\},$

Inferior user n is inserting at idle frequency spectrum a (t)=1 o'clock, and the probability

that forwards state g ' from state g to is expressed as:

$P_{{\mathrm{gg}}^{\′}}^1=P\{({\mathrm{\ϵ}}_{g^{\′}-1}-\left(\frac{{\mathrm{\ϵ}}_g+{\mathrm{\ϵ}}_{g-1}}{2}\right)+v_n)\≤X\≤({\mathrm{\ϵ}}_{g^{\′}}-\left(\frac{{\mathrm{\ϵ}}_g+{\mathrm{\ϵ}}_{g-1}}{2}\right)+v_n)\},$

ε _gBe state S _g(t) the upper limit is set point,

g=1,2,…,g,…G,g′=1,2,…,g′,…G,g≠g′，

X is a positive integer k, at k=0, and 1,2 ..., value between K, K is a limited positive integer, is set point,

λ is time user's average data arrival rate

v _nBe the transmission rate that time user can reach,

$v_n=\mathrm{\Δ\; f}\·{\mathrm{Log}}_2(1+{\mathrm{\τ}}_n\·\frac{h_n{W}_n}{{\mathrm{\σ}}^2+\mathrm{\Σ}{\stackrel{\·}{I}}_{i^{\′}{j}^{\′}}}),$ Wherein:

i′=1,2,…,i′…,I,I=M,j′=1,2,…,j′…,J,J=M,i′≠j′，

I ', j ' they are respectively the sequence numbers of two users' selected from said N user subcarrier, the sequence number of two idle frequency bands that on data, equal to use,

Δ f is adjacent two number of sub-carrier i ', and the frequency interval of j ' is set point,

τ _nBe a constant, with the error rate BER of inferior user n _nRelevant, for additive white Gaussian noise channel, τ _nWith BER _nBetween satisfy:

${\mathrm{\τ}}_n=\frac{1.5}{-\ln \left({5\mathrm{BER}}_n\right)},$

σ ²One-sided power spectrum density for additive white Gaussian noise is given value,

h _nBe the channel gain of inferior user n, be given value,

W _nBe total transmitted power of each time user n,

Be inferior user n _iSubcarrier i ' to inferior user n _jThe interference that causes of subcarrier j ',

Be expressed as

${\stackrel{\·}{I}}_{i^{\′}{j}^{\′}}(d_{i^{\′}{j}^{\′}},W_{i^{\′}})={\left|h_{i^{\′}{j}^{\′}}\right|}^2{W}_{i^{\′}}{T}_s{\∫}_{d_{i^{\′}{j}^{\′}}-\mathrm{\Δ\; f}/2}^{d_{i^{\′}{j}^{\′}}+\mathrm{\Δ\; f}/2}{\left(\frac{\mathrm{Sin}\mathrm{\π}{f}_{i^{\′}}{T}_s}{\mathrm{\π}{f}_{i^{\′}}{T}_s}\right)}^2{\mathrm{Df}}_{i^{\′}},$ Wherein:

h _{I ' j '}Be the channel gain of subcarrier i ' on subcarrier j ',

W _{I '}Be the inferior user n on the subcarrier i ' _iTotal transmitted power, W _{I '}=W _n,

T _sBe OFDM symbol duration, be given value

d _{I ' j '}Be the frequency distance between two number of sub-carrier i ', the j ', be given value

f _{I '}Be time user n _iThe frequency of place subcarrier i ',

Step (3.2.2), confirm to make the optimization aim function of main user's maximize revenue by following formula:

Satisfy. ${\stackrel{\&CenterDot;}{I}}_{i^{\&prime;}{j}^{\&prime;}}(d_{i^{\&prime;}{j}^{\&prime;}},W_{i^{\&prime;}{j}^{\&prime;}})<{\stackrel{\&CenterDot;}{I}}_{\mathrm{Spec}}$

${\mathrm{BER}}_{n_j}<{\mathrm{BER}}_{n_j\mathrm{Spec}}$ , wherein:

$\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{a}_{{\mathrm{ni}}^{\&prime;}}\left(t\right)\&le;1$

i′=1,2,…,i′…M,j′=1,2,…,j′…M,i′≠j′

Discount factor Beta representes with β, guarantees the bounded and the convergence of total discount income, and β is 0 < β < 1 value,

I ', j ' expression idle sub-carrier frequency is given value,

Be a T * N matrix, row is t, and expression time slot, row are behavior a of time user _n(t),

Be time user n _iSubcarrier i ' to inferior user n _jThe interference that causes of subcarrier j '

Higher limit, be set point,

Be inferior user n _jThe upper limit threshold of maximum bit error rate is set point,

a _{Ni '}(t) the inferior user n of expression t time slot on subcarrier i ' _iBehavior,

Be illustrated in time slot t an a can only be arranged at most on subcarrier i ' _{Ni '}(t)=1 any active ues,

Step (3.2.3) is found the solution main user's maximum return R with fruit machine Restless Bandits ceaselessly ^*, according to state transition probability matrix Main user's idle frequency band number M, inferior user's number N, discount factor Beta=β, inferior User Status is counted StateNumber=G+1, Alpha=zeros (N; G+1) be the rank matrix of complete zero N * (G+1), down with, R0=zeros (N, G+1), R1=ones (N; G+1) be the rank matrix of complete 1 N * (G+1), and P0=zeros (G+1, G+1, N), P1=P0; Utilize index value function f unction [Delta]=calc_index (M, N, Beta, StateNumber, Alpha; R0, R1, P0 P1) calculates the index value Delta in order to statement use order of the pairing idle frequency spectrum of each time user, finds out pairing user of minimum index value; As preferential index value, the user priority that preferential index value is corresponding uses idle frequency band, constructs the enquiry form of each time user index value Delta, and all deposits in the main user's data storehouse with this minimum index value;

Step (4), main user distributes frequency spectrum according to the following steps:

The main user of step (4.1) is according to each time user current states vector { s ₁, s ₂..., s _NEnquiry form, the index value sorts from small to large, and sends to said N time user successively and use pairing idle frequency band information successively, comprises access slot,

Step (4.2) is if obtain allowing a _n(t)=1, insert frequency band next time slot time user and transmit data, the normal operation of main user base station monitoring whole system,

Step (4.3) when time slot finishes, is carried out as follows,

Step (4.3.1), inferior user adds up the buffer memory of oneself and the information of last time slot transmission data, if still there are data need transmit and data volume ε _CacheDo not surpass threshold value, then cache information is sent to main user, 0<ε _Cache≤ε _Spec,

Step (4.3.2), main user is vectorial according to inferior user's all N of information updating time users' system mode,

Step (4.4) repeats (4.1) and went on foot for (4.3) step, does not have idle frequency spectrum to hire out up to main user, and main user sends the right to use that stops notice and regain frequency spectrum, calculates the rent that each time user should pay and sends the information that rent is confirmed.

Advantage of the present invention is main user's in the cognitive radio system income is divided into state income and flow income two parts, and inferior user pays rent according to the actual operating position of oneself.In the real-time system user's selection course modeling is become Restless Bandits model; On the one hand main user's income is improved; The calculating of index value can run through a plurality of time slots in system's running on the other hand; Main user only need table look-up when each time slot decision-making, has improved operational efficiency.

Description of drawings

Fig. 1 is based on the cognitive radio frequency spectrum distribution method system figure of main user's maximize revenue of OFDM.

Fig. 2 is based on the cognitive radio frequency spectrum distribution method schematic diagram of main user's maximize revenue of OFDM.

Fig. 3; Model algorithm sketch map among the embodiment during different interference-limited;

Restless Bandits algorithm values among the figure;

greedy algorithm value,

random algorithm financial value.

Fig. 4; The asynchronous model algorithm sketch map of available band quantity among the embodiment;

Restless Bandits algorithm values among the figure; greedy algorithm value, random algorithm financial value.

Fig. 5; Model algorithm sketch map when time number of users is available band quantity twice among the embodiment;

Restless Bandits algorithm values among the figure;

greedy algorithm value, random algorithm financial value.

Embodiment

Step (1), potential inferior user to the use request that main user sends idle frequency spectrum, comprises the information that their buffer data size, average data arrival rate λ, geographical position, the error rate require in the information when producing spectrum requirement;

Step (2), main user collects each described frequency spectrum and uses request, carries out as follows,

Step (2.1); Main user determines the criteria for classifying of state; The state of system is made up of potential inferior state of user; State at t user n of time slot can by how many decisions of its metadata cache amount; Inferior state of user set; Be called for short system mode vector available

expression; The status number that

can divide when G was illustrated in time user's data buffer area data are arranged, G+1 is the sum of state.State S ₀(t) the expression buffer data size does

State S _G(t) expression required buffer memory surpassed inferior user data cache district ability to bear (

Threshold value for inferior user n data buffer area), press for the frequency band transmission data and run well to guarantee it, this time this moment user has turned to other main user's network.According to actual conditions, inferior user can send cache information, s at each time slot and main user interactions _nBe the state S of time user n at time slot t _n(t):

$s_n=\left\{\begin{array}{cc}{S}_0\left(t\right)& {\mathrm{\&epsiv;}}^n=0\\ S_1\left(t\right)& 0<{\mathrm{\&epsiv;}}^n<{\mathrm{\&epsiv;}}_1^n\\ .& \\ .& \\ .& \\ S_g\left(t\right)& {\mathrm{\&epsiv;}}_{g-1}^n<{\mathrm{\&epsiv;}}^n<{\mathrm{\&epsiv;}}_g^n\\ .& \\ .& \\ .& \\ S_G\left(t\right)& {\mathrm{\&epsiv;}}^n>{\mathrm{\&epsiv;}}_{\mathrm{spec}}^n\end{array}\right.$

Step (2.2), main user is provided with corresponding rent, establishes the system benefit function, and price of spectrum is made up of two parts: data traffic price and state price, the total revenue R of T time slot is expressed as:

$R=\underset{t=0}{\overset{T-1}{\mathrm{\&Sigma;}}}(R_v^a\left(t\right)+R_s^a\left(t\right)),$

Inferior user n can be expressed as in the behavior of time slot t

a _n(t)=1 expression time user n is active at time slot t, takies idle frequency spectrum and carries out transfer of data, a _n(t)=0 expression time user does not take idle frequency spectrum,

Be that main user of the t moment is to all times user behavior a in the network _n(t) the flow rent of collecting, the price of single Subscriber Unit data traffic does

Be that main user of the t moment is to all times user behavior a in the network _n(t) the state rent of collecting, the set of single User Status price

Corresponding to inferior state of user set

Step (2.3), main user with above-mentioned information just the frequency spectrum Tenancy Agreement Spectrum Lease Protocol of short-term be called for short SLP, be broadcast to all said potential users in its coverage;

Step (3) is accomplished the preceding preparation of frequency spectrum lease by following process,

Step (3.1) if said time potential user do not accept the access rules that main user is provided with, then turns to other main users' network, otherwise receives information to said main user's transmission,

Step (3.2), main user calculates the preferential index value table of a selected M idle frequency band from the individual inferior user of N according to inferior number of users N that accepts said frequency spectrum Tenancy Agreement and main user M idle frequency band when the time slot t, M≤N, step is following:

Step (3.2.1) is asked state transition probability matrix, and the state transition probability matrix the when behavior of inferior user n is a is defined as $P_n^a={\left[p_{{\mathrm{Gg}}^{\&prime;}}\left(t\right)\right]}_{(G+1)\&times;(G+1)},$ Wherein

can be written as:

Element depend on time user's behavior act a _n(t), average data arrival rate λ, the transmission rate v that can reach when inserting frequency band _n, according to Poisson probability assignments matrix

K=0,1,2 ..., X is the data volume that current time slots arrives buffer area.In the OFDM transmission system, the transmission rate that inferior user n can reach representes with following formula,

$v_n=\mathrm{\&Delta;f}\&CenterDot;{\log }_2(1+{\mathrm{\&tau;}}_n\&CenterDot;\frac{h_n{W}_n}{{\mathrm{\&sigma;}}^2+\mathrm{\&Sigma;}{\stackrel{\&CenterDot;}{I}}_{i^{\&prime;}{j}^{\&prime;}}}),$

Main user estimates time user's transmission rate calculating transition probability matrix, h _nBe the channel gain of time user n, W _nBe total transmitted power of each time user n, σ ²Be the one-sided power spectrum density of additive white Gaussian noise,

Representative time user n _iSubcarrier interference that other subcarrier is caused, τ _nBe a constant, with the error rate BER of inferior user n _nRelevant, then be expressed as for additivity Gauss white noise channel (AWGN):

${\mathrm{\&tau;}}_n=\frac{1.5}{-\ln \left({5\mathrm{BER}}_n\right)},$

Be difficult to guarantee the quadrature of different user signal in the OFDM transmission system, need to consider interference effect, inferior user n _iSubcarrier i ' to inferior user n _jThe interference that causes of subcarrier j '

Be expressed as:

${\stackrel{\&CenterDot;}{I}}_{i^{\&prime;}{j}^{\&prime;}}(d_{i^{\&prime;}{j}^{\&prime;}},W_{i^{\&prime;}})={\left|h_{i^{\&prime;}{j}^{\&prime;}}\right|}^2{W}_{i^{\&prime;}}{T}_s{\&Integral;}_{d_{i^{\&prime;}{j}^{\&prime;}}-\mathrm{\&Delta;f}/2}^{d_{i^{\&prime;}{j}^{\&prime;}}+\mathrm{\&Delta;f}/2}{\left(\frac{\sin \mathrm{\&pi;}{f}_{i^{\&prime;}}{T}_s}{\mathrm{\&pi;}{f}_{i^{\&prime;}}{T}_s}\right)}^2{\mathrm{df}}_{i^{\&prime;}},$

D wherein _{I ' j '}Be the frequency distance between two number of sub-carrier i ', the j ', W _{I '}Be total transmitted power of the inferior user n on the subcarrier i ', T _sBe OFDM symbol duration, h _{I ' j '}Be the channel gain of subcarrier i ' on subcarrier j ', Δ f is the frequency interval of adjacent sub-carrier, f _{I '}Be time frequency of user n place subcarrier i ',

Step (3.2.2), confirm the optimization aim function that Restless Bandits model can solve:

Satisfy. ${\stackrel{\&CenterDot;}{I}}_{i^{\&prime;}{j}^{\&prime;}}(d_{i^{\&prime;}{j}^{\&prime;}},W_{i^{\&prime;}{j}^{\&prime;}})<{\stackrel{\&CenterDot;}{I}}_{\mathrm{Spec}}$

${\mathrm{BER}}_{n_j}<{\mathrm{BER}}_{n_j\mathrm{spec}}$

$\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{a}_{{\mathrm{ni}}^{\&prime;}}\left(t\right)\&le;1$

i′=1,2,…,i′…M,j′=1,2,…,j′…M,i′≠j′

N representes time user, and i ', j ' expression free sub-band, discount factor β guarantee the bounded and the convergence of total discount income, and β is 0<β<1 value,

Represent main user all strategy sets that can take when each time slot is done judgement, wherein a kind of strategy

Be a T * N rank matrix, wherein the capable n of t classifies a as _n(t), represent the behavior of time user n at time slot t,

Expression time user n _iSubcarrier i ' to inferior user n _jThe interference that causes of subcarrier j '

Must be less than higher limit

Expression time user n _jMaximum bit error rate can not surpass upper limit threshold

Being illustrated in subcarrier i ' upward can only have an any active ues at most at time slot t,

Step (3.2.3) is found the solution main user's maximum return R with fruit machine Restless Bandits ceaselessly ^*, according to state transition probability matrix

Main user's idle frequency band number M, inferior user's number N, discount factor Beta=β, inferior User Status is counted StateNumber=G+1, Alpha=zeros (N; G+1) be the rank matrix of complete zero N * (G+1), down with, R0=zeros (N, G+1), R1=ones (N; G+1) be the rank matrix of complete 1 N * (G+1), and P0=zeros (G+1, G+1, N), P1=P0; Utilize index value function f unction [Delta]=calc_index (M, N, Beta, StateNumber, Alpha; R0, R1, P0 P1) calculates the index value Delta in order to statement use order of the pairing idle frequency spectrum of each time user, finds out pairing user of minimum index value; As preferential index value, the user priority that preferential index value is corresponding uses idle frequency band, constructs the enquiry form of each time user index value Delta, and all deposits in the main user's data storehouse with this minimum index value; Step (4), main user distributes frequency spectrum according to the following steps:

Step (4.1), main user is according to each time user current states vector { s ₁, s ₂..., s _NEnquiry form, the index value sorts from small to large, and sends to said N time user successively and use pairing idle frequency band information successively, comprises access slot,

Step (4.2) is if obtain allowing a _n(t)=1, insert frequency band next time slot time user and transmit data, the normal operation of main user base station monitoring whole system,

Step (4.3) when time slot finishes, is carried out as follows,

Step (4.3.1), inferior user adds up the buffer memory of oneself and the information of last time slot transmission data, if still there are data need transmit and data volume ε _CacheDo not surpass threshold value, then cache information is sent to main user, 0<ε _Cache≤ε _Spec,

Step (4.3.2), main user is vectorial according to inferior user's all N of information updating time users' system mode,

Step (4.4) repeats (4.1) and went on foot for (4.3) step, does not have idle frequency spectrum to hire out up to main user, and main user sends the right to use that stops notice and regain frequency spectrum, calculates the rent that each time user should pay and sends the information that rent is confirmed.

In conjunction with the embodiment of accompanying drawing and instance explanation based on the cognitive radio frequency spectrum distribution method of main user's maximize revenue of OFDM.

The first step is confirmed system architecture, main user and time user's requirement.

Fig. 1 is based on the suitable system figure of cognitive radio frequency spectrum distribution method of main user's maximize revenue of OFDM, and main user carries out alternately through CCCH with time user's base station, and the coverage of inferior user network relates to a plurality of main users' network.

The arrival rate of supposing data to be sent meets Poisson distribution; The average data arrival rate of inferior user n is λ (n); The arrival of the expression time data volume of user in each time slot process meets the Poisson distribution that Mean Speed is λ (n); The symbol time Ts=4 μ s of OFDM, network subcarrier width Δ f=0.3125MHz.This external system white Gaussian noise variances sigma ², average channel decline gain h _n, inferior user is to the error rate requirement of system, in the system to the interference-limited I of intercarrier _SpecBe given value.System is current to have 6 idle frequency bands, has a plurality of user applies to use frequency spectrum.

In second step, main user determines the criteria for classifying and the price of spectrum of state, and obtains time user's agreement.

Time state of user is determined by the metadata cache amount in this example.Time slot t how much inferior User Status is divided into according to the metadata cache amount

5 kinds, S wherein ₀(t) the expression data volume is 0, and inferior user does not need frequency spectrum; S ₁(t) to S ₃(t) data volume increases gradually; S ₄(t) time user the time satisfies and has turned to other main user network because can not obtain frequency spectrum.State price S is set ₁(t) rent is 2, and the every high one-level of state adds 2; The flow price is that every Mb price is 2.

Main user is broadcast to time user with decision-making, and whether inferior user gets involved this network based on the situation decision-making of oneself, is provided with 10 users and agrees that access network uses frequency spectrum.

In the 3rd step, main user sets up Restless Bandits model based on Given information, calculates the concordance list after the lease process begins, the calculating of index can with the carrying out simultaneously alternately of primary and secondary user.

At first calculate time user's transition probability matrix, find the solution time user emission power higher limit according to channel conditions, interference requirement,

${\stackrel{\&CenterDot;}{I}}_{i^{\&prime;}{j}^{\&prime;}}(d_{i^{\&prime;}{j}^{\&prime;}},W_{i^{\&prime;}})={\left|h_{i^{\&prime;}{j}^{\&prime;}}\right|}^2{W}_{i^{\&prime;}}{T}_s{\&Integral;}_{d_{i^{\&prime;}{j}^{\&prime;}}-\mathrm{\&Delta;f}/2}^{d_{i^{\&prime;}{j}^{\&prime;}}+\mathrm{\&Delta;f}/2}{\left(\frac{\sin \mathrm{\&pi;}{f}_{i^{\&prime;}}{T}_s}{\mathrm{\&pi;}{f}_{i^{\&prime;}}{T}_s}\right)}^2{\mathrm{df}}_{i^{\&prime;}},$

Error rate demand according to inferior user is calculated the maximum data rate that can reach when each time user uses frequency spectrum with formula.

$v_n=\mathrm{\&Delta;f}\&CenterDot;{\log }_2(1+{\mathrm{\&tau;}}_n\&CenterDot;\frac{h_n{W}_n}{{\mathrm{\&sigma;}}^2+\mathrm{\&Sigma;}{\stackrel{\&CenterDot;}{I}}_{i^{\&prime;}{j}^{\&prime;}}})$

Calculating then can be written as:

P wherein _EEBe illustrated in current time slots time user cache data volume and be continuously 0 probability, can obtain relational expression

p _BKExpression time user reduces the probability of again getting back to current main user network because of data volume because of data cached surpassing after threshold value turns to other main user networks, simultaneously p _OTExpression time user turns to behind other main user networks at the current time slots still probability in current main user network not, p _OT+ p _BX=1.Suppose state I _iThe upper bound be ε _i, inferior user can be expressed as from the probability that state g is transformed into state g ' under the situation that does not insert frequency spectrum (a (t)=0):

$P_{{\mathrm{gg}}^{\&prime;}}^0=P\{({\mathrm{\&epsiv;}}_{g^{\&prime;}-1}-\left(\frac{{\mathrm{\&epsiv;}}_g+{\mathrm{\&epsiv;}}_{g-1}}{2}\right))\&le;X\&le;({\mathrm{\&epsiv;}}_{g^{\&prime;}}-\left(\frac{{\mathrm{\&epsiv;}}_g+{\mathrm{\&epsiv;}}_{g-1}}{2}\right))\},$

If a (t)=1, so

$P_{{\mathrm{gg}}^{\&prime;}}^1=P\{({\mathrm{\&epsiv;}}_{g^{\&prime;}-1}-\left(\frac{{\mathrm{\&epsiv;}}_g+{\mathrm{\&epsiv;}}_{g-1}}{2}\right)+v_n)\&le;X\&le;({\mathrm{\&epsiv;}}_{g^{\&prime;}}-\left(\frac{{\mathrm{\&epsiv;}}_g+{\mathrm{\&epsiv;}}_{g-1}}{2}\right)+v_n)\},$

Poisson probability assignments matrix wherein $P(X=k)=e^{-\mathrm{\&lambda;}}\frac{{\mathrm{\&lambda;}}^k}{k!},k=\mathrm{0,1,2},...$

Next, establish the optimization aim function that Restless Bandits model can solve, discount factor is got Beta=β=0.9,

Satisfy. ${\stackrel{\&CenterDot;}{I}}_{i^{\&prime;}{j}^{\&prime;}}(d_{i^{\&prime;}{j}^{\&prime;}},W_{i^{\&prime;}{j}^{\&prime;}})<{\stackrel{\&CenterDot;}{I}}_{\mathrm{Spec}}$

${\mathrm{BER}}_{n_j}<{\mathrm{BER}}_{n_j\mathrm{spec}}$

$\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{a}_{{\mathrm{ni}}^{\&prime;}}\left(t\right)\&le;1$

i′=1,2,…,i′…M,j′=1,2,…,j′…M,i′≠j′

N representes time user, i ', j ' expression free sub-band.M in time slot t among the individual time user of N is enlivened, and main user obtains the inferior then state of user of rental income of any active ues according to the markoff process variation of state transition probability matrix for

.Other time user pays rent Its state transition probability matrix does

Income is given a discount in time, and the wireless frequency spectrum assignment problem is converted into definite optimal policy

Make average folding back income R ^*Maximization.Utilize the index value of the pairing idle frequency spectrum of index value function calculation each time user; Find out pairing user of minimum index value; With this minimum index value as preferential index value; The user priority that preferential index value is corresponding uses idle frequency band, the structure enquiry form, and all deposit in the main user's data storehouse;

In the 4th step, begin real-time frequency spectrum lease process.

Main user is according to each time user current states vector { s ₁, s ₂..., s _NEnquiry form; The index value sorts from small to large; And send to said N time user successively and use pairing idle frequency band information successively, comprising access slot, the inferior user who obtains allowing inserts frequency band at next time slot and transmits data; The normal operation of main user monitoring whole system at this moment simultaneously can continue the computation index table; When time slot finished, inferior user added up the data volume that oneself buffer memory and last time slot send, and was still having data to transmit and data volume surpasses threshold value, to main user report buffer memory and data quantity transmitted; Main user is according to inferior user's information update system state vector.

Said process repeats to hope to regain frequency spectrum or do not have inferior user to hope to continue to use frequency spectrum up to main user, and then lease process is ended, and inferior user pays rent according to agreement.

After the algorithm that the present invention is proposed was tested, the gained result can monitor the channel value environment more accurately.Model algorithm sketch map when Fig. 3 is different interference-limited, Fig. 4 is the asynchronous model algorithm sketch map of available band quantity, Fig. 5 is the model algorithm sketch map of time number of users when being available band quantity twice.The present invention is compared with method at random with greedy here.

The present invention's The Realization of Simulation on PC is to use the Matlab language to programme.MATLAB is a kind of senior matrix language, comprises control statement, function, data structure, input and output and OOP characteristics, is the set that comprises the great amount of calculation algorithm.It has the mathematical operation function that will use in more than 600 engineering, can realize the various computing functions that the user is required easily.Natural language based on the cognitive radio frequency spectrum distribution method embodiment program of main user's maximize revenue of OFDM is following:

Beginning

The number that time user is set is 10, and sequence number 1 to 10, average data arrival rate are 1.2Mbps, and error rate demand is 10 ^-7To 10 ^-3Between random number;

The idle frequency spectrum number that main user is set is 6, and metadata cache is at interval with 1.5M, and OFDM transmission and channel related parameter are set;

Find the solution time user's maximum transmission power according to

formula circulation in the 3rd step;

According to the v in the 3rd step _nFormula is found the solution the maximum data rate of time user;

The gain matrix that setting and state are corresponding with action, comprise flow price and state price two-part and;

With between number of states, data arrives speed, state area, the inferior user maximum data rate that can reach, according to the state transition probability matrix of each time of computational methods cycle calculations user under different behaviour decision makings of in the 3rd step;

According to state transition probability matrix Main user's idle frequency band number M, inferior user's number N, discount factor Beta=β, inferior User Status is counted StateNumber=G+1, and (N G+1) is the rank matrix of complete zero N * (G+1) to Alpha=zeros; Down with, R0=zeros (N, G+1), (N G+1) is the rank matrix of complete 1 N * (G+1), P0=zeros (G+1 to R1=ones; G+1, N), P1=P0, utilizing the index value computing function is function f unction [Delta]=calc_index (M, N, Beta; StateNumber, Alpha, R0, R1, P0 P1) calculates { s ₁, s ₂..., s ₁₀The corresponding concordance list of all possible combination;

With index that calculates and state vector { s ₁, s ₂..., s ₁₀Correspondence deposits in the table;

It is 1s that each time slots is set, and 1000 time slots of emulation begin emulation real time spectrum lease process altogether, and initial state vector { s is set ₁, s ₂..., s ₁₀}={ 1,1..., 1}, carry out follow procedure at each time slot:

The corresponding state of current each time user is found out in circulation, confirms the current states vector;

Table look-up according to state vector and to find out 6 times minimum user's corresponding sequence number of index under this state, be placed in the active set;

Inferior user 1 is produced one 0 to 1 random number R and; Judge that time user 1 is whether in active set; If add the income of user 1 last time under current state and transmission rate, judge the inferior state of user 1 when current time slots finishes according to a (t)=1 o'clock user's 1 state transition probability matrix with the random number R and that produces in income then; Judge if not in active set then income add 0, judge the inferior state of user 1 when current time slots finishes with Rand according to a (t)=0 o'clock user's 1 state transition probability matrix;

Circulation is carried out the operation of top single step to remaining time user, obtains new state vector;

Main user's total revenue that 1000 time slots obtain adding up when finishing, program are carried out and are repeatedly asked average total revenue.

Finish

Claims (1)

1. make the cognitive radio frequency spectrum distribution method of OFDM master user maximize revenue, it is characterized in that, The Realization of Simulation according to the following steps on PC:

Step (1); The use solicited message that at least one potential inferior user base station is sent idle frequency spectrum to a main user base station; Wherein comprise at least: buffer data size separately, average data arrival rate λ, geographical position and error rate demand, said user base station and main user base station are designated hereinafter simply as time user and main user;

Step (2), the frequency spectrum that main user collects each said user according to the following steps uses request:

Step (2.1); At time slot t; Main user is the inferior User Status set that state is set up a t time slot with the metadata cache amount of each said user under time slot t; Be called for short the system mode vector, expression with :

S _gThe expression state is the inferior user of g, and state is used S _g(t) expression,

S ₀(t) the expression buffer data size is 0, increase progressively successively,

S _G(t) expression desired data buffer memory has surpassed the storage capacity of this time user data cache amount, and press for the frequency band transmission data and run well guaranteeing, other main user network just ready about,

G+1 is the state sum,

Step (2.2), corresponding to inferior user's different conditions, main user is provided with every Mb data traffic price and state price, and along with state increases progressively, the state price increases progressively by the equivalent of setting, thereby sets up following T time slot total revenue R:

$R=\underset{t=0}{\overset{T-1}{\mathrm{\&Sigma;}}}(R_v^a\left(t\right)+R_s^a\left(t\right)),$

is time slot t unit data flow price; It is set point; Be time-varying

is time slot t state price; It is set point; Be time-varying

The behavioral unity of above-mentioned two kinds of prices that inferior user is taken place is expressed as

a _n(t)=1 expression time user carries out transfer of data, a at the idle frequency spectrum that time slot t takies main user _n(t)=0 expression time user does not take main user's idle frequency spectrum,

Step (2.3), main user is called for short SLP with the frequency spectrum Tenancy Agreement Spectrum LeaseProtocol that the above-mentioned information in the step (2.2) forms a short-term, is broadcast to all said potential users in its coverage;

Step (3), main user carries out the frequency spectrum lease according to the following steps and prepares:

Step (3.1) if said time potential user do not accept the frequency spectrum Tenancy Agreement SLP that main user is provided with in step (2.3), then turns to the network at other main user place, if accept, then sends and accepts message to said main user,

Step (3.2), main user calculates the preferential index value table of a selected M idle frequency band from the individual inferior user of N according to inferior number of users N that accepts said frequency spectrum Tenancy Agreement and main user M idle frequency band when the time slot t, M≤N, step is following:

Step (3.2.1), the state transition probability matrix

the when behavior that main user calculates time user n according to the following steps is a

wherein:

p _EEFor t user n of current time slots buffer data size is continuously 0 probability,

p _BKFor t user n of current time slots reduces the probability of again getting back to current main user network because of buffer data size because of buffer data size surpasses after the buffer memory threshold value turns to other main user network, be the estimated value of setting,

p _OTFor t user n of current time slots turns to behind other main user network still the not probability in current main user network, be the estimated value of setting,

p _OT+p _BK=1，

Inferior user n is not inserting at idle frequency spectrum a (t)=0 o'clock, and the probability

that forwards state g ' from state g to is expressed as:

$P_{{\mathrm{gg}}^{\&prime;}}^0=P\{({\mathrm{\&epsiv;}}_{g^{\&prime;}-1}-\left(\frac{{\mathrm{\&epsiv;}}_g+{\mathrm{\&epsiv;}}_{g-1}}{2}\right))\&le;X\&le;({\mathrm{\&epsiv;}}_{g^{\&prime;}}-\left(\frac{{\mathrm{\&epsiv;}}_g+{\mathrm{\&epsiv;}}_{g-1}}{2}\right))\},$

Inferior user n is inserting at idle frequency spectrum a (t)=1 o'clock, and the probability

that forwards state g ' from state g to is expressed as:

$P_{{\mathrm{gg}}^{\&prime;}}^1=P\{({\mathrm{\&epsiv;}}_{g^{\&prime;}-1}-\left(\frac{{\mathrm{\&epsiv;}}_g+{\mathrm{\&epsiv;}}_{g-1}}{2}\right)+v_n)\&le;X\&le;({\mathrm{\&epsiv;}}_{g^{\&prime;}}-\left(\frac{{\mathrm{\&epsiv;}}_g+{\mathrm{\&epsiv;}}_{g-1}}{2}\right)+v_n)\},$

ε _gBe state S _g(t) the upper limit is set point,

g=1,2,…,g,…G,g′=1,2,…,g′,…G,g≠g′，

X is a positive integer k, at k=0, and 1,2 ..., value between K, K is a limited positive integer, is set point,

λ is time user's average data arrival rate

v _nBe the transmission rate that time user can reach,

$v_n=\mathrm{\&Delta;\; f}\&CenterDot;{\mathrm{Log}}_2(1+{\mathrm{\&tau;}}_n\&CenterDot;\frac{h_n{W}_n}{{\mathrm{\&sigma;}}^2+\mathrm{\&Sigma;}{\stackrel{\&CenterDot;}{I}}_{i^{\&prime;}{j}^{\&prime;}}}),$ Wherein:

i′=1,2,…,i′…,I,I=M,j′=1,2,…,j′…,J,J=M,i′≠j′，

I ', j ' they are respectively the sequence numbers of two users' selected from said N user subcarrier, the sequence number of two idle frequency bands that on data, equal to use,

Δ f is adjacent two number of sub-carrier i ', and the frequency interval of j ' is set point,

τ _nBe a constant, with the error rate BER of inferior user n _nRelevant, for additive white Gaussian noise channel, τ _nWith BER _nBetween satisfy:

${\mathrm{\&tau;}}_n=\frac{1.5}{-\ln \left({5\mathrm{BER}}_n\right)},$

σ ²Be the one-sided power spectrum density of additive white Gaussian noise, be own knowledge value,

h _nBe the channel gain of inferior user n, be own knowledge value,

W _nBe total transmitted power of each time user n,

Be inferior user n _iSubcarrier i ' to inferior user n _jThe interference that causes of subcarrier j ',

Be expressed as

${\stackrel{\&CenterDot;}{I}}_{i^{\&prime;}{j}^{\&prime;}}(d_{i^{\&prime;}{j}^{\&prime;}},W_{i^{\&prime;}})={\left|h_{i^{\&prime;}{j}^{\&prime;}}\right|}^2{W}_{i^{\&prime;}}{T}_s{\&Integral;}_{d_{i^{\&prime;}{j}^{\&prime;}}-\mathrm{\&Delta;\; f}/2}^{d_{i^{\&prime;}{j}^{\&prime;}}+\mathrm{\&Delta;\; f}/2}{\left(\frac{\mathrm{Sin}\mathrm{\&pi;}{f}_{i^{\&prime;}}{T}_s}{\mathrm{\&pi;}{f}_{i^{\&prime;}}{T}_s}\right)}^2{\mathrm{Df}}_{i^{\&prime;}},$ Wherein:

h _{I ' j '}Be the channel gain of subcarrier i ' on subcarrier j ',

W _{I '}Be the inferior user n on the subcarrier i ' _iTotal transmitted power, W _{I '}=W _n,

T _sBe OFDM symbol duration, be own knowledge value

d _{I ' j '}Be the frequency distance between two number of sub-carrier i ', the j ', be own knowledge value

f _{I '}Be time user n _iThe frequency of place subcarrier i ',

Step (3.2.2), confirm to make the optimization aim function of main user's maximize revenue by following formula:

Satisfy. ${\stackrel{\&CenterDot;}{I}}_{i^{\&prime;}{j}^{\&prime;}}(d_{i^{\&prime;}{j}^{\&prime;}},W_{i^{\&prime;}{j}^{\&prime;}})<{\stackrel{\&CenterDot;}{I}}_{\mathrm{Spec}}$

${\mathrm{BER}}_{n_j}<{\mathrm{BER}}_{n_j\mathrm{Spec}}$ , wherein:

$\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{a}_{{\mathrm{ni}}^{\&prime;}}\left(t\right)\&le;1$

i′=1，2，…，i′…M，j′=1，2，…，j′…M，i′≠j′

Discount factor Beta representes with β, guarantees the bounded and the convergence of total discount income, β O β 1 value,

I ', j ' expression idle sub-carrier frequency is own knowledge value,

Be a T * N matrix, row is t, and expression time slot, row are behavior a of time user _n(t),

Be time user n _iSubcarrier i ' to inferior user n _jThe interference that causes of subcarrier j '

Higher limit, be set point,

Be inferior user n _jUpper limit value of cutting off from of maximum bit error rate is set point,

a _{Ni '}(t) the inferior user n of expression t time slot on subcarrier i ' _iBehavior,

Be illustrated in time slot t an a can only be arranged at most on subcarrier i ' _{Ni '}(t)=1 any active ues,

Step (3.2.3) is found the solution main user's maximum return R with fruit machine Restless Bandits ceaselessly ^*, according to state transition probability matrix

Main user's idle frequency band number M, inferior user's number N, discount factor Beta=β, inferior User Status is counted StateNumber=G+1, Alpha=zeros (N; G+1) be the rank matrix of complete zero N * (G+1), down with, R0=zeros (N, G+1), R1=ones (N; G+1) be the rank matrix of complete 1 N * (G+1), and P0=zeros (G+1, G+1, N), P1=P0; Utilize index value function f unction [Delta]=calc_index (M, N, Beta, StateNumber, Alpha; R0, R1, P0 P1) calculates the index value Delta in order to statement use order of the pairing idle frequency spectrum of each time user, finds out pairing user of minimum index value; As preferential index value, the user priority that preferential index value is corresponding uses idle frequency band, constructs the enquiry form of each time user index value Delta, and all deposits in the main user's data storehouse with this minimum index value;

Step (4), main user distributes frequency spectrum according to the following steps:

The main user of step (4.1) is according to each time user current states vector { s ₁, s ₂..., s _NEnquiry form, the index value sorts from small to large, and sends to said N time user successively and use pairing idle frequency band information successively, comprises access slot,

Step (4.2) is if obtain allowing a _n(t)=1, insert frequency band next time slot time user and transmit data, the normal operation of main user base station monitoring whole system,

Step (4.3) when time slot finishes, is carried out as follows,

Step (4.3.1), inferior user adds up the buffer memory of oneself and the information of last time slot transmission data, if still there are data need transmit and data volume ε _CacheDo not surpass threshold value, then cache information is sent to main user, 0<ε _Cache≤ε _Spec,

Step (4.3.2); Main user is according to inferior user's all N of information updating time users' system mode vector; Step (4.4) repeats (4.1) and went on foot for (4.3) step, does not have idle frequency spectrum to hire out up to main user; Main user sends the right to use that stops notice and regain frequency spectrum, calculates the rent that each time user should pay and sends the information that rent is confirmed.

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