CN103402263B - For energy-conservation spectrum allocation and the chance access mechanism of low rights communication system - Google Patents

Abstract

Energy-conservation spectrum allocation for low rights communication system provided by the invention and chance access mechanism, comprise step: initialize; Calculate optimal allocation and waiting time; For from user's original allocation frequency spectrum resource; Wait and upgrade channel after accessing from user; Calculate in lower gap for the moment and make to expect the maximized channel of through-put rate from user; For distributing frequency spectrum resource from user. The present invention is under rational spectrum allocation strategy, it is possible to reduce the energy consumption carrying out accessing on primary user's channel from user. Simultaneously under the protection of chance access mechanism, the performance of primary user can not be much affected. Namely the present invention is when known channel distribution parameter, the gain and loss from user by balance " switching or waiting ", obtain a kind of energy-conservation spectrum allocation strategy for low rights communication system, significantly reduce the expense produced frequency spectrum access procedure from user; And by chance access mechanism reasonable in design, the interference being subject to of primary user can be controlled under preset value.

Description

For energy-conservation spectrum allocation and the chance access mechanism of low rights communication system

Technical field

What the present invention relates to is the method for wireless communication field, specifically a kind of energy-conservation spectrum allocation and chance access mechanism.

Background technology

Low rights communication system is (usually lower owing to not obtaining frequency spectrum mandate or the grade of service, hereinafter referred to as from user) coexist to a certain extent by mode and the high authority communication system (normally frequency spectrum mandate user or the grade of service are higher, hereinafter referred to as primary user) of dynamic spectrum access. This kind of dynamic spectrum access technology, i.e. cognitive radio technology, can make to utilize certain tactful channel perception from user, finding that primary user exits " frequency spectrum cavity-pocket " that channel produces certain period and accesses should " frequency spectrum cavity-pocket ", under the prerequisite affecting primary user as little as possible, improve the availability of frequency spectrum, obtain the throughput capacity of self.

Through the literature search of prior art is found, Chinese Patent Application No. is: 201210106394.X, name is called: based on the method for allocating dynamic frequency spectrums of contract in wireless network, provide a kind of method for allocating dynamic frequency spectrums based on contract, channel is concluded the business with different quality, effectively improve the income of mandate system, can effectively reduce the interference between mandate system and cognitive radio system simultaneously; It is published in the paper of Globecom in 2011: DecentralizedOnlineLearningAlgorithmsforOpportunisticSpe ctrumAccess, provide one make multiple user's through-put rate maximized while, take into account different from the spectrum allocation strategy of user's through-put rate fairness. In addition, Chinese Patent Application No. is: 201210377971.9, name is called: the cut-in method that in wireless body area network, single-frequency point channel is quick self-adapted, and giving a kind of making can the dynamical access scheme of quick self-adapted channel parameter the channel of exponential distribution or hyperexponential distribution from user. The program make single from user after being assigned with certain frequency spectrum resource, it is possible to the quick self-adapted access on single channel.

But, along with wireless body area network based on smart mobile phone and the rise of Wearable device network in this year, wireless network is more and more higher to the standby requirement of smart mobile phone or other portable computing equipments. The universal urgent communication needing a kind of low-power consumption of this type of network application, existing spectrum allocation strategy fails to fully take into account power saving.

The paper " Energy-EfficientDistributedSpectrumSensingforCognitiveSe nsorNetworks " being published in IEEESENSORSJOURNAL in 2011 gives and a kind of is applicable to the low-power consumption access way from user. How the method is emphatically it is considered that to reduce and balance between channel perception and transmission data. However, it is contemplated that to the hub-and-spoke configuration topology of wireless body area network or similar network, whole network carries out the power consumption of channel switching in fact far above the power consumption of Centroid channel perception. Considering from this point, the present invention considers emphatically how to carry out spectrum allocation can reduce the whole frequency carrying out channel switching from user network as far as possible meeting under certain through-put rate requires. Under normal conditions, after accessing certain channel for some time from user, the probability that primary user returns will increase greatly, at this time spectrum allocation center is initiatively the access chance that primary user distributes on another one channel, will be conducive to the through-put rate increased from user and reduces from user the interference of primary user.

Summary of the invention

For weak point of the prior art, the present invention provides a kind of energy-conservation spectrum allocation for low rights communication system and chance access mechanism.

The present invention is achieved by the following technical solutions, and the present invention comprises the following steps:

The described energy-conservation spectrum allocation for low rights communication system and chance access mechanism, comprise the steps:

Step 1: initialize channel and primary user, from the information of user;

Step 2: length and from long during user's optimum wait on each channel when calculating the optimal allocation of each channel;

Step 3: for from user's original allocation frequency spectrum resource;

Step 4: wait and access channel from user;

Step 5: upgrade channel state;

Step 6: calculate in lower gap for the moment and make to expect the maximized channel of through-put rate from user;

Step 7: calculate after terminating from the access of user's epicycle, be assigned with channel ch_jProbability;

Step 8: for distributing frequency spectrum resource from user.

Preferably, described step 1 comprises the following steps:

Step 1.1: from regulator or other spectrum detection device, the channel quantity N that acquisition primary user has and primary user are to each channel ch_i, i=1,2 ..., the occupancy p of N_i,B, namely each channel idle rate is p_i,I=1-p_i,B; Obtain the acceptable maximum interference probability �� of primary user; Obtain the average occupied duration E of each channel_i,BAnd long E during average free_i,I; Obtain free time, the time of the taking long distribution parameter �� of each channel_i,I����_i,B;

Step 1.2: obtain and require R from the minimum through-put rate of user_th; Obtain from the time long t required for user's switching channels_h, acquisition carries out data transmission respectively from user, the power P of Channel Detection, channel switching_t��P_s��P_h;

Step 1.3: by channel temporally burst, each time slice is set, instant gap, length be t_slot; t_slotSize is all channel E_i,IThe mean value hoped for a long time during 1/10th or all channel idle of mean value;

Step 1.4: the state transitionmatrix calculating each channel, specific as follows,

$p_{i,10}=\frac{t_{\mathrm{slot}}}{E_{i,I}};$ p_i,11=1-p_i,10

$p_{i,01}=\frac{t_{\mathrm{slot}}}{E_{i,B}};$ p_i,00=1-p_i,01

Wherein, p_i,10For next non-slotted channel i is the probability " free time " transferring " taking " to by state, p_i,11For next non-slotted channel i is the probability " free time " transferring " free time " to by state, p_i,01For next non-slotted channel i is the probability that " taking " transfers " free time " to by state, p_i,00For next non-slotted channel i is the probability that " taking " transfers " taking " to by state;

Step 1.5: the state vector at current time slots k arranging each channel is ��_k={��_k(1), ��_k(2) ..., ��_k(N) }, described state vector is the state set of each channel, certain channel wherein time gap k state be this channel this time gap idle probability.

Preferably, described step 2 comprises the steps:

Step 2.1: according to the distribution function of each channel, calculates from long t during user's best access on each channel_i,t, described the best refers to, when the interference of primary user being controlled under maximum crash rate thresholding from user, when making access, length is maximum; For the channel of exponential distribution, when this best accesses, length can be obtained by following formula,

$t_{i,t}=-\frac{1}{{\mathrm{\λ}}_{i,i}}\ln (1-\mathrm{\η})$

Wherein, ��_i,IFor the inverse that channel i free time length is expected;

Step 2.2: calculate from long t during user's optimum wait on each channel_i,w, for the channel of exponential distribution, during this optimum wait, length can be obtained by following formula,

t_i,w=E_i,B��

Preferably, described step 3 comprises the steps:

Step 3.1: with the idle rate p of each channel_i,iThe state vector �� of initialize channel₁, i.e. ��₁(j)=p_i,j, j=1,2 ... N, wherein, ��₁J () is the state value of channel j gap when first;

Step 3.2: by ��₁In channel corresponding to maximum value distribute to from user, during distribution, length is t_i,t��

Preferably, described wait accesses channel from user and refers to that spectrum allocation center waits is from the end of user at current time slots access procedure.

Preferably, described step 5 comprises the steps:

Step 5.1: for from user in current time slots, instant gap k, the channel ch being assigned with_iIf access result is " failure ", and namely primary user occupies channel ch in current time slots_i, then value corresponding for this channel in state vector is set to 0; If access result is " success ", namely primary user is at current time slots unoccupied channel ch_i, then value corresponding for this channel in state vector is set to 1;

Step 5.2: be not yet assigned to the channel from user in current time slots, its state value corresponding in state vector remains unchanged.

Preferably, described step 6 comprises the steps:

Step 6.1: the idle probability �� calculating gap for the moment under each channel according to channel-aware history and channel state probability transfer matrix_iIt is (k+1), specific as follows,

Wherein, ��_i(k) for channel i time gap k in state value;

Step 6.2: according to the calculation result of described step 6.1, selected except current channel, the channel that in other channels, idle probability is maximum, it is assumed that be channel ch_j��

Preferably, described calculating is assigned with channel ch after terminating from the access of user's epicycle_jProbability refer to:

Assuming that current channel is ch_iIf, ch_iWith ch_jFor same channel, then being distributed to by this channel from the probability of user is 1, and forwards the 8th step to; Otherwise, calculate and it be assigned with channel ch_jProbability p, specific as follows,

$p=\frac{R_{i,\mathrm{th}}(p_{i,I}{t}_{i,t}+t_{i,w})-p_{i,I}(t_{i,t}-t_s)}{R_{i,\mathrm{th}}{t}_{i,w}-p_{i,I}{t}_h}$

Wherein, in upper formula, t_sFor from the time needed for user awareness channel, R_i,thFor being p from user's through-put rate in current all channel idle rates_i,IEquivalent through-put rate, specific as follows,

R_i,th=��_i(R_th-c_i)+c_i

Wherein, for formula ��_i��c_iAs follows

${\mathrm{\α}}_i=\frac{{2p}_{i,I}}{p_{i,I}+p_{j,I}}$

$c_i=\frac{p_{i,I}(t_{i,t}-t_s)}{p_{i,I}{t}_{i,t}+t_{i,w}}$

Wherein, p_j,IFor the idle rate of channel j.

Preferably, described refer to for distributing frequency spectrum resource from user, spectrum allocation center with the probability of p by channel ch_jDistributing to from user, during distribution, length is t_i,t, then forward step 5 to; Current channel is distributed to from user with the probability of 1-p by spectrum allocation center, waits for a period of time from user at current channel, and waiting time is t_i,w, then forward step 6 to.

Compared with prior art, the useful effect of the present invention is: The present invention gives and is applicable to low rights communication system when with high authority coexistence of communication systems, can effectively reduce the spectrum allocation strategy from user's communication power consumption. This strategy considers emphatically from user's channel switching frequency and from the balance between user's through-put rate. For switching channels expense, higher than in network, the network of node communication expense is optimized this strategy by certain, under the prerequisite meeting the through-put rate certain from user, by reducing the frequency from user network switching channels to greatest extent, make from user when coexisting with primary user, reduce the energy expenditure switching by channel and causing to greatest extent. Compared with traditional spectrum allocation strategy, the present invention has fairly obvious energy-conserving action.

Accompanying drawing explanation

By reading with reference to the detailed description that non-limiting example is done by the following drawings, the other features, objects and advantages of the present invention will become more obvious:

Fig. 1 is master and slave user network spectra sharing system schematic diagram;

Fig. 2 is the concrete implementing procedure figure of spectrum allocation schemes, namely for from the energy-conservation spectrum allocation of user and access mechanism schema;

Fig. 3, Fig. 4, Fig. 5 are analogous diagram, illustrating the scheme that the present invention proposes and every Performance comparision of two kinds of contrast schemes, wherein, Fig. 3 is for presetting through-put rate and actual throughput rates graph of a relation, Fig. 4 is for presetting through-put rate and energy expenditure graph of a relation, and Fig. 5 is for presetting through-put rate and collision rate graph of a relation.

Embodiment

Below in conjunction with specific embodiment, the present invention is described in detail. The technician contributing to this area is understood the present invention by following examples further, but does not limit the present invention in any form. It should be appreciated that to those skilled in the art, without departing from the inventive concept of the premise, it is also possible to make some distortion and improvement. These all belong to protection scope of the present invention.

Fig. 1 is master and slave user network spectra sharing system schematic diagram, arranges primary user when communicating, and free time, the time of the taking length distribution of primary user's channel are exponential distribution. Master and slave user network is at a distance of relatively near, and therefore they can not take identical channel with gap for the moment, otherwise co-channel interference will occur. This scheme realizes the spectrum allocation schemes being applicable to low rights communication system by following step.

The first step, the information of initialize channel and master and slave user.

The following step of information of described initialize channel and master and slave user:

1) from regulator or other spectrum detection device, the channel quantity N that acquisition primary user has and primary user are to each channel ch_i(i=1,2 ..., N, lower with) occupancy p_i,B, namely each channel idle rate is p_i,I=1-p_i,B; Obtain the acceptable maximum interference probability �� of primary user; Obtain the average occupied duration E of each channel_i,BAnd long E during average free_i,I; Obtain free time, the time of the taking long distribution parameter �� of each channel_i,I����_i,B, and E_i,BCorresponding cumulative distribution function F_i,B, and E_i,ICorresponding cumulative distribution function F_i,I��

2) the minimum through-put rate requirement R from user is obtained_th. Obtain from the time long t required for user's switching channels_h, acquisition carries out data transmission respectively from user, the power P of Channel Detection, channel switching_t��P_s��P_h��

3) by channel temporally burst, each time slice is set, instant gap, length be t_slot��t_slotSize is all channel E_i,I/ 10th of mean value.

4) the state transitionmatrix of each channel is calculated, specific as follows,

$p_{i,10}=\frac{t_{\mathrm{slot}}}{E_{i,I}};$ p_i,11=1-p_i,10

$p_{i,01}=\frac{t_{\mathrm{slot}}}{E_{i,B}};$ p_i,00=1-p_i,01

Wherein, p_i,10For next non-slotted channel i is the probability " free time " transferring " taking " to by state, p_i,11For next non-slotted channel i is the probability " free time " transferring " free time " to by state, p_i,01For next non-slotted channel i is the probability that " taking " transfers " free time " to by state, p_i,00For next non-slotted channel i is the probability that " taking " transfers " taking " to by state.

5) each channel ch is set_iOriginal state be p_i,I. Described original state is the idle probability of channel gap when initial, namely this time gap can be from user's probability used. The state vector at current time slots k arranging each channel is ��_k={��_k(1), ��_k(2) ..., ��_k(N) }. Described state vector is the state set of each channel, certain channel wherein time gap k state be this channel this time gap idle probability.

2nd step, calculates from long when length during user's best access on each channel and optimum wait.

Calculate from long t during user's best access on each channel_i,t, for the channel of exponential distribution, when this best accesses, length can be obtained by following formula,

$t_{i,t}=-\frac{1}{{\mathrm{\λ}}_{i,i}}\ln (1-\mathrm{\η})$

Wherein, ��_i,iFor the inverse that channel i free time length is expected.

Calculate from long t during user's optimum wait on each channel_i,w, for the channel of exponential distribution, during this optimum wait, length can be obtained by following formula,

t_i,w=E_i,B

In a change case, described 2nd step comprises the steps:

1) calculate from user when the best access of each channel long.

${\∫}_0^{t_{i,t}}\frac{1-F_{i,I}\left(x\right)}{E_{i,I}}\mathrm{dx}=\mathrm{\η}$

Substitute in the first step free time length cumulative distribution function F obtained_i,IAnd free time length expectation E_i,I, solve above equation, draw from user at channel ch_iBest access time long t_i,t��

2) calculate from user when the optimum wait of each channel long.

t_i,w=E_i,B

3rd step, for from user's original allocation frequency spectrum resource.

Described for comprise the following steps from user's original allocation frequency spectrum resource:

1) with the idle rate p of channel_i,iThe state vector �� of initialize channel₁, i.e. ��₁(j)=p_i,j, j=1,2 ... N, wherein, ��₁J () is the state value of channel j gap when first.

2) by ��₁In channel corresponding to maximum value distribute to from user, during distribution, length is t_i,t��

4th step, waits and accesses channel from user.

Described wait accesses channel from user and refers to that spectrum allocation center waits is from the end of user at current time slots access procedure.

5th step, upgrades channel state.

Described renewal channel state comprises the following steps:

1) for the channel ch being assigned with in current time slots (time gap k) or current time slots end from user_iIf access result is " failure ", and namely primary user occupies channel ch in current time slots_i, then �� is set_iK () is 0; If access result is " success ", namely primary user is at current time slots unoccupied channel ch_i, then �� is set_iK () is 1. Wherein ��_i(k) for channel i time gap k state value.

2) being not yet assigned to the channel from user in current time slots, its state corresponding in state vector value is constant.

6th step, calculates in lower gap for the moment and makes from the maximized channel of user's through-put rate.

Described calculating makes to comprise the following steps from the maximized channel of user's through-put rate:

1) the idle probability �� of gap for the moment under each channel is calculated according to channel-aware history and channel state probability transfer matrix_i(k+1), for channel ch_iIt is specific as follows,

Wherein, ��_i(k) for channel i time gap k state value.

2) according to above-mentioned steps 1) calculation result, selected except current channel, the channel that in other channels, idle probability is maximum, it is assumed that be channel ch_j��

7th step, calculates after terminating from the access of user's epicycle, is assigned with channel ch_jProbability.

Described calculating is assigned with channel ch after terminating from the access of user's epicycle_jProbability refer to:

1) suppose that current channel is ch_iIf, ch_iWith ch_jFor same channel, then being distributed to by this channel from the probability of user is 1, and forwards the 8th step to; Otherwise, calculate and it be assigned with channel ch_jProbability p, specific as follows,

$p=\frac{R_{i,\mathrm{th}}(p_{i,I}{t}_{i,t}+t_{i,w})-p_{i,I}(t_{i,t}-t_s)}{R_{i,\mathrm{th}}{t}_{i,w}-p_{i,I}{t}_h}$

Wherein, in upper formula, t_sFor from the time needed for user awareness channel, R_i,thFor being p from user's through-put rate in current all channel idle rates_i,IEquivalent through-put rate, specific as follows,

R_i,th=��_i(R_th-c_i)+c_i

Wherein, for formula ��_i��c_iAs follows

${\mathrm{\α}}_i=\frac{{2p}_{i,I}}{p_{i,I}+p_{j,I}}$

$c_i=\frac{p_{i,I}(t_{i,t}-t_s)}{p_{i,I}{t}_{i,t}+t_{i,w}}$

Wherein, p_j,IFor the idle rate of channel j.

2) calculate from user with Probability p by current channel ch_iJump to ch_jTime, from the through-put rate R that user can obtain_i(p), specific as follows,

$R_i\left(p\right)=\frac{t_{i,\mathrm{valid}\_\mathrm{trans}}}{t_{i,\mathrm{total}\_\mathrm{trans}}+t_{i,\mathrm{wait}}}$

Upper formula is the ratio from effectively transmission time and total time (transmission time and waiting time sum) user is within certain period, wherein being calculated as follows of each subitem,

t_{i,valid_trans}=N_sp_i,i(t_i,t-t_s-pt_h)

t_{i,total_trans}=N_sp_i,it_i,t

t_i,wait=N_s(1-p)t_i,w

Wherein, N_sFor completing the number of times of the channel perception needed for transformation task.

Finally can obtain,

$R_i\left(p\right)=\frac{p_{i,I}(t_{i,t}-t_s-{\mathrm{pt}}_h)}{p_{i,I}{t}_{i,t}+(1-p)t_{i,w}}$

3) calculate under take turns channel ch in access_jDistribute to the probability from user.

Make the through-put rate R obtained from user_iP () equals equivalence through-put rate R_i,thIn, namely

R_i(p)=R_i,th

Separate this equation can from user's epicycle access terminate after, be assigned with channel ch_jProbability p, specific as follows,

$p=\frac{R_{i,\mathrm{th}}(p_{i,I}{t}_{i,t}+t_{i,w})-p_{i,I}(t_{i,t}-t_s)}{R_{i,\mathrm{th}}{t}_{i,w}-p_{i,I}{t}_h}$

8th step, for distributing frequency spectrum resource from user.

Described refer to for distributing frequency spectrum resource from user, spectrum allocation center with the probability of p by channel ch_jDistributing to from user, during distribution, length is t_i,t, then forward the 5th step to; Current channel is distributed to from user with the probability of 1-p by spectrum allocation center, waits for a period of time from user at current channel, and waiting time is t_i,w, then forward the 6th step to.

[embodiment]

Setting distributable primary user's channel quantity is 5, and when the free time length of each channel distributes and takies, length distribution is the exponential distribution that parameter is different. Long distribution parameter, the free time length distribution parameter when taking of 5 channels are respectively ��_B={0.06,0.06,0.06,0.06,0.06},��_I={ 0.01,0.03,0.02,0.04,0.05}; The collision rate tolerance limit of setting primary user is 0.3; Gap when setting primary user's channel length is 50000.

The energy-conservation spectrum allocation that Fig. 3, Fig. 4, Fig. 5 compare the present invention's proposition contrasts comparing of scheme performance with chance access mechanism and other two kinds. Described two kinds of contrast schemes, wherein, contrast scheme one is maximum throughput rate scheme, is with the difference of the present invention program, whenever taking turns from user one after access terminates, always distributes it and expects the channel that through-put rate is maximum; Contrast scheme two is least energy consumption scheme, is with the difference of the present invention, always accesses on current channel from user.

Fig. 3 illustrates the default through-put rate of three kinds of schemes and the graph of a relation of actual throughput rates. As can be seen from this figure, the preset value that coincide that the actual throughput rates of the scheme that the present invention proposes is relatively good, two kinds of contrast schemes then cannot set through-put rate.

Fig. 4 illustrates the default through-put rate of three kinds of schemes and the graph of a relation of energy consumption. As can be seen from this figure, its energy consumption of scheme that the present invention proposes increases along with the growth of default through-put rate, generally lower than the energy consumption of contrast scheme one. Although the scheme that the present invention proposes totally higher than the energy consumption of contrast scheme two, but cannot reach preset value due to the through-put rate of contrast scheme two in energy consumption, the scheme that therefore the present invention proposes still has superiority.

Fig. 5 illustrates in the scheme of the present invention's proposition situation about primary user being disturbed from user. As can be seen from this figure, the present invention propose scheme can by from user to the Interference Control of primary user under the jamming margin of primary user, such that it is able to effectively protect primary user.

Above specific embodiments of the invention are described. It is understood that the present invention is not limited to above-mentioned particular implementation, those skilled in the art can make various distortion or amendment within the scope of the claims, and this does not affect the flesh and blood of the present invention.

Claims (3)

1. the energy-conservation spectrum allocation for low rights communication system and chance access mechanism, it is characterised in that, comprise the steps:

Step 1: initialize channel and primary user, from the information of user;

Step 2: length and from long during user's optimum wait on each channel when calculating the optimal allocation of each channel;

Step 3: for from user's original allocation frequency spectrum resource;

Step 4: wait and access channel from user;

Step 5: upgrade channel state;

Step 6: calculate in lower gap for the moment and make to expect the maximized channel of through-put rate from user;

Step 7: calculate after terminating from the access of user's epicycle, be assigned with channel ch_jProbability;

Step 8: for distributing frequency spectrum resource from user;

Described step 1 comprises the following steps:

Step 1.1: from regulator or other spectrum detection device, the channel quantity N that acquisition primary user has and primary user are to each channel ch_i, i=1,2 ..., the occupancy p of N_i,B, namely each channel idle rate is p_i,I=1-p_i,B; Obtain the acceptable maximum interference probability �� of primary user; Obtain the average occupied duration E of each channel_i,BAnd long E during average free_i,I; Obtain free time, the time of the taking long distribution parameter �� of each channel_i,I����_i,B;

Step 1.2: obtain and require R from the minimum through-put rate of user_th; Obtain from the time long t required for user's switching channels_h, acquisition carries out data transmission respectively from user, the power P of Channel Detection, channel switching_t��P_s��P_h;

Step 1.3: by channel temporally burst, each time slice is set, instant gap, length be t_slot; t_slotSize is all channel E_i,IThe mean value hoped for a long time during 1/10th or all channel idle of mean value;

Step 1.4: the state transitionmatrix calculating each channel, specific as follows,

$p_{i,10}=\frac{t_{slot}}{E_{i,I}};$ p_i,11=1-p_i,10

$p_{i,01}=\frac{t_{slot}}{E_{i,B}};$ p_i,00=1-p_i,01

Wherein, p_i,10For next non-slotted channel i is the probability " free time " transferring " taking " to by state, p_i,11For next non-slotted channel i is the probability " free time " transferring " free time " to by state, p_i,01For next non-slotted channel i is the probability that " taking " transfers " free time " to by state, p_i,00For next non-slotted channel i is the probability that " taking " transfers " taking " to by state;

Step 1.5: the state vector at current time slots k arranging each channel is ��_k={ ��_k(1), ��_k(2) ..., ��_k(N) }, described state vector is the state set of each channel, certain channel wherein time gap k state be this channel this time gap idle probability;

Described step 2 comprises the steps:

Step 2.1: according to the distribution function of each channel, calculates from long t during user's best access on each channel_i,t, described the best refers to, when the interference of primary user being controlled under maximum crash rate thresholding from user, when making access, length is maximum; For the channel of exponential distribution, when this best accesses, length can be obtained by following formula,

$t_{i,t}=-\frac{1}{{\mathrm{\λ}}_{i,I}}ln(1-\mathrm{\η})$

Wherein, ��_i,IFor the free time length distribution parameter of channel i;

Step 2.2: calculate from long t during user's optimum wait on each channel_i,w, for the channel of exponential distribution, during this optimum wait, length can be obtained by following formula,

t_i,w=E_i,B;

Described step 3 comprises the steps:

Step 3.1: with the idle rate p of each channel_i,iThe state vector �� of initialize channel₁, i.e. ��₁(j)=p_i,j, j=1,2 ... N, wherein, ��₁J () is the state value of channel j gap when first;

Step 3.2: by ��₁In channel corresponding to maximum value distribute to from user, during distribution, length is t_i,t;

Described step 5 comprises the steps:

Step 5.1: for from user in current time slots, instant gap k, the channel ch being assigned with_iIf access result is " failure ", and namely primary user occupies channel ch in current time slots_i, then value corresponding for this channel in state vector is set to 0; If access result is " success ", namely primary user is at current time slots unoccupied channel ch_i, then value corresponding for this channel in state vector is set to 1;

Step 5.2: be not yet assigned to the channel from user in current time slots, its state value corresponding in state vector remains unchanged;

Described step 6 comprises the steps:

Step 6.1: the idle probability �� calculating gap for the moment under each channel according to channel-aware history and channel state probability transfer matrix_iIt is (k+1), specific as follows,

Wherein, ��_i(k) for channel i time gap k in state value;

Step 6.2: according to the calculation result of described step 6.1, selected except current channel, the channel that in other channels, idle probability is maximum, it is assumed that be channel ch_j;

Wherein, p_i,11For next non-slotted channel i is the probability " free time " transferring " free time " to by state, p_i,01For next non-slotted channel i is the probability that " taking " transfers " free time " to by state.

2. the energy-conservation spectrum allocation for low rights communication system according to claim 1 and chance access mechanism, it is characterised in that, described wait accesses channel from user and refers to that spectrum allocation center waits is from the end of user at current time slots access procedure.

3. the energy-conservation spectrum allocation for low rights communication system according to claim 1 and chance access mechanism, it is characterised in that, described calculating is assigned with channel ch after terminating from the access of user's epicycle_jProbability refer to:

Assuming that current channel is ch_iIf, ch_iWith ch_jFor same channel, then being distributed to by this channel from the probability of user is 1, and forwards the 8th step to; Otherwise, calculate and it be assigned with channel ch_jProbability p, specific as follows,

$p=\frac{R_{i,th}(p_{i,I}{t}_{i,t}+t_{i,w})-p_{i,I}(t_{i,t}-t_s)}{R_{i,th}{t}_{i,w}-p_{i,I}{t}_h}$

Wherein, in upper formula, t_sFor from the time needed for user awareness channel, R_i,thFor being p from user's through-put rate in current all channel idle rates_i,IEquivalent through-put rate, specific as follows,

R_i,th=��_i(R_th-c_i)+c_i

Wherein, for formula ��_i��c_iAs follows

${\mathrm{\α}}_i=\frac{2p_{i,I}}{p_{i,I}+p_{j,I}}$

$c_i=\frac{p_{i,I}\left(t_{i,t}-t_s\right)}{p_{i,I}{t}_{i,t}+t_{i,w}}$

Wherein, p_j,IFor the idle rate of channel j;

Wherein, from the time length required for user's switching channels be t_h, require as R from the minimum through-put rate of user_th;

Described refer to for distributing frequency spectrum resource from user, spectrum allocation center with the probability of p by channel ch_jDistributing to from user, during distribution, length is t_i,t, then forward step 5 to; Current channel is distributed to from user with the probability of 1-p by spectrum allocation center, waits for a period of time from user at current channel, and waiting time is t_i,w, then forward step 6 to.