CN103929255B - A kind of based on multi channel cognitive user efficiency optimization method - Google Patents

Abstract

The invention discloses a kind of based on multi channel cognitive user efficiency optimization method, belong to digital communication technology field.The present invention is by the many Xindas energy efficiency model based on cognitive radio, the process of cognitive user efficiency optimization will be converted to the optimization of the dual problem to its energy efficiency model, based on the transmission structure of Frame, to occurring that the multiple detection time points in one section of perception section search time of optimum detecting period calculate the preferred overall transmission power (comprising idle and busy two states) of its correspondence respectively, therefrom find out the overall transmission power corresponding to minimum efficiency and detection time point again, be stored in the frame structure of current Frame to be sent, as the optimum detecting period of current data frame, optimum allocation power.The present invention is used for cognitive radio communication systems, and its beneficial effect is: efficient optimum detecting period point and the transmit power allocation exporting cognitive user, the efficiency of optimize communicate transmission system when spectrum shortage.

Description

A kind of based on multi channel cognitive user efficiency optimization method

Technical field

The present invention relates to digital communicating field, particularly a kind of based on the cognitive user efficiency optimization method in the multichannel system of cognitive radio technology.

Background technology

Along with the development of wireless communication technology, the especially continuous maturation of 3G, LTE technology, the demand of people to data service is constantly expanded, and current frequency spectrum resource can not meet data traffic requirement.For above problem, one is called that the communication technology of cognitive radio (CR) is arisen at the historic moment, and CR refers to a wireless communication system having perception to environment, possess " learning ability ".By the actual conditions of cognitive nodes to environment measuring, dynamic-configuration and the relevant parameter that communicates (as coded modulation, access way, network etc.), guarantee system communication quality, rationally, efficiency utilization " frequency spectrum cavity-pocket ", simultaneously in communication process, when insuring telecommunication service quality, how consumption of energy is also the focus paid close attention to now as much as possible less.

The energy-saving and cost-reducing of current existing consideration wireless communication procedure of cognitive radio and efficiency being optimized integration is for single-channel situation mostly, such as document " Y.WuandD.H.K.Tsang, " Energy-efficientspectrumsensingandtransmissionforcogniti veradiosystem [J] .CommunicationsLetters, IEEE, 2011, 15 (5): 545-547. " perception power consumptions different in radio cognitive radio system under single channel is indicated, through-put power consumes, no-load power consumption is on the impact of optimum detecting period, and document " L.Li, X.Zhou, H.Xu, etal., Energy-efficienttransmissionincognitiveradionetworks [C] .CCNCIEEE2010, 9 (1): 1-5. " mention under single channel to optimal transmission and power allocation scheme under the interference-limited of authorized user.And at document " Y.Pei, Y.C.Liang, K.C.The, etal.Energy-efficientdesignofsequentialchannelsensinginc ognitiveradionetworks:optimalsensingstrategy, powerallocation, andsensingorder [J] .SelectedAreasinCommunications, IEEEJournalon, 2011, 29 (8): 1648-1659. " in, propose a kind of efficiency optimization based on multi channel cognitive user, it is by the serial perception to multichannel cognitive user, analyze perceptual strategy (when to start and end perception, transmission), access strategy (through-put power size) and perception order (channel-aware order) impact on cognitive user efficiency, but because of the mode that its implementation procedure is serial, the implementation procedure of its efficiency optimization is caused to there is inefficient defect, the communication transmission needs of cognitive radio system can not be met preferably.

Summary of the invention

Goal of the invention of the present invention is: based on the frequency spectrum perception technology under multichannel, proposes a kind of parallel based on the cognitive user efficiency optimization method under multichannel, to improve the treatment effeciency that efficiency is optimized.

One of the present invention, based on multi channel cognitive user efficiency optimization method, comprises the following steps:

Step 1: based on the frame transmission time T of Frame, arrange section search time of detecting period, is separated into the identical test detecting period point τ in multiple interval by section described search time _test;

Step 2: before current data to be transmitted frame transmission, aware services device is successively to each test detecting period point τ _testcalculate preferred overall transmission power with preferred efficiency η (τ _test, P ⁽⁰⁾, P ⁽¹⁾) ^*:

201: arrange Two Variables parameter: λ 1, the initial value of λ 2, λ 1 is that the initial value of 0, λ 2 is greater than 10^ (-10);

202: judge whether λ 2 is less than or equal to preset value ε with the difference of λ 1, if so, then perform step 204; Otherwise perform step 203, described preset value ε is for being less than or equal to the positive number of 10^ (-10);

203: calculate F (λ by calling interior point method function f mincon (x, y, z) _mid) value, if F (λ _mid) be less than or equal to 0, then make λ 2 equal λ _mid, and perform step 202; If F is (λ _mid) be greater than 0, then make λ 1 equal λ _mid, and perform step 202;

Wherein λ _midrepresent the average of λ 1 and λ 2;

In described interior point method function f mincon (x, y, z),

The corresponding optimization aim min{E (τ of x _test, P ⁽⁰⁾, P ⁽¹⁾)-λ _midc (τ _test, P ⁽⁰⁾, P ⁽¹⁾), the overall average energy of multichannel cognitive user $E({\mathrm{\τ}}_{test},P^{\left(0\right)},P^{\left(1\right)})=E\[{\mathrm{MP}}_{sens}{\mathrm{\τ}}_{test}+\underset{i=1}{\overset{M}{\Σ}}(T-{\mathrm{\τ}}_{test})P_i\],$ The average transmission rate of multichannel cognitive user symbol E [] represents averaged, P ⁽¹⁾represent the overall transmission power of cognitive user under busy condition, P ⁽⁰⁾represent cognitive user overall transmission power in an idle state, P _sensrepresent the perception power of cognitive user, M represents the number of subchannels of cognitive user, P _i=α _{0, i}p ⁽⁰⁾+ α _{1, i}p ⁽¹⁾+ β _{0, i}p ⁽⁰⁾+ β _{1, i}p ⁽¹⁾represent the average transmission gross power of subchannel i, C _i=α _{0, i}r _{00, i}+ α _{1, i}r _{01, i}+ β _{0, i}r _{10, i}+ β _{1, i}r _{11, i}represent the average transmission rate of subchannel i, wherein α _{0, i}, α _{1, i}, β _{0, i}, β _{1, i}represent that channel i is the probability of detected state a, b, c, d, r _{00, i}, r _{01, i}, r _{10, i}, r _{11, i}represent transmission rate during detected state a, b, c, d of respective channels i, described detected state a, b, c, d are followed successively by: detected state a, and cognitive user and authorized user are idle condition; Detected state b, cognitive user is idle condition and authorized user is busy condition; Detected state c, cognitive user is busy condition and authorized user is idle condition; Detected state d, cognitive user and authorized user are busy condition;

Y represents the total mean power restrictive condition of cognitive user M sub-channels wherein P _avrepresent the average maximum transmission power of cognitive user;

Z represents the average interference power restrictive condition of every sub-channels wherein I _irepresent the interference power that in subchannel i, authorized user receives, represent the maximum average interference that authorized user can accept;

204: parameters λ ^*, described λ ^*value be λ 1 ~ λ 2, and optimize formula F (λ)=min{E (τ based on efficiency _test, P ⁽⁰⁾, P ⁽¹⁾)-λ C (τ _test, P ⁽⁰⁾, P ⁽¹⁾), the value of getting variable λ is parameter lambda ^*time corresponding overall transmission power P ⁽¹⁾and P ⁽⁰⁾for current test detecting period point τ _testpreferred overall transmission power with and according to efficiency formula calculate and described preferred overall transmission power with corresponding preferred efficiency η (τ, P ⁽⁰⁾, P ⁽¹⁾) ^*;

Step 3: at each perception test time point τ based on described step 1 and 2 acquisitions _testcorresponding preferred energy efficiency eta (τ, P ⁽⁰⁾, P ⁽¹⁾) ^*in, get minimum preferred energy efficiency eta (τ, P ⁽⁰⁾, P ⁽¹⁾) ^*corresponding perception test time point, preferably overall transmission power with for optimum detecting period, the optimum allocation power of current data to be transmitted frame.

In sum, owing to have employed technique scheme, the invention has the beneficial effects as follows: in multi channel radio cognitive radio system, the optimum detecting period point of parallel output cognitive user and transmit power allocation, achieve the efficiency of the optimize communicate transmission system when spectrum shortage.

Accompanying drawing explanation

Fig. 1 is the traffic model schematic diagram of cognitive user and authorized user;

Fig. 2 is the wide band detection schematic diagram of cognitive user;

Fig. 3 is the data frame structure of cognitive user.

Embodiment

For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with execution mode and accompanying drawing, the present invention is described in further detail.

In cognitive user as shown in Figure 1 and the traffic model of authorized user, dispensing device is utilized to be divided into the subchannel that disjoint M bandwidth is equal on frequency spectrum the bandwidth B of an authorized user (access frequency spectrum B), this M sub-channels transmits data simultaneously or is in resting state, cognitive user utilizes the authorized user state of its wideband detection device perception simultaneously M sub-channels, as shown in Figure 2, if there is energy, be namely expressed as busy condition, otherwise be idle condition.

But we select broadband perceived spectral shared access scheme for cognitive user, in this access scheme, no matter which kind of state authorized user is in, cognitive user all by the mandate band transmissions data of insertion authority user, and adjusts through-put power according to sensing results.If authorized user is in seizure condition (i.e. busy condition), then cognitive user transmission adopts lower-wattage, limits the interference to authorized user; If authorized user is in idle condition, cognitive user transmission adopts higher-wattage.And utilize the authorized user state of cognitive user wideband detection device (the down converter f1 ~ fM shown in figure and energy detector 1 ~ M) perception simultaneously M sub-channels as shown in Figure 2.Suppose i-th (i=1,2 ... M) state of channel authorization user is detected as free time (H _{0, i}) time, the total power consumption (transmission consumes and circuitry consumes sum, also claims the average transmission gross power of channel i) of cognitive user is designated as P _i ⁽⁰⁾, and the state of the i-th channel authorization user is detected as and takies (H _{1, i}) time, the total power consumption of cognitive user is designated as P _i ⁽¹⁾, in the detected state schematic diagram of the output shown in Fig. 2, " 0 " the corresponding idle condition in each subscript, " 1 " corresponding busy condition; To the average transmission gross power P of channel i _i, distinguish idle condition and busy condition by subscript " (0) " and " (1) ".

Owing to being a binary test problems to the state-detection of channel i, therefore have four kinds of detected states that may exist, be respectively: detected state a, b, c, d are followed successively by: detected state a, cognitive user and authorized user are idle condition; Detected state b, cognitive user is idle condition and authorized user is busy condition; Detected state c, cognitive user is busy condition and authorized user is idle condition; Detected state d, cognitive user and authorized user are busy condition.Under above-mentioned four kinds of detected states, remember that the probability of its correspondence is respectively α _{0, i}, α _{1, i}, β _{0, i}, β _{1, i}(lower target state indications depends on the state of authorized user), the transmission rate under detected state a, b, c, d of channel i can be calculated by shannon formula, it is expressed as successively: r _{00, i}, r _{01, i}, r _{10, i}, r _{11, i}, then the average transmission rate of subchannel i can be expressed as C _i=α _{0, i}r _{00, i}+ α _{1, i}r _{01, i}+ β _{0, i}r _{10, i}+ β _{1, i}r _{11, i}, the overall transmission power of channel i is expressed as P _i=α _{0, i}p _i ⁽⁰⁾+ α _{1, i}p _i ⁽¹⁾+ β _{0, i}p _i ⁽⁰⁾+ β _{1, i}p _i ⁽¹⁾.

Meanwhile, in order to keep the budget of cognitive user long term power, the total mean power of cognitive user M sub-channels will be restricted, and restrictive condition is wherein T, τ are the frame structure parameter of cognitive user Frame, and as shown in Figure 3, T represents the frame transmission time of Frame, and τ represents detecting period, P _avrepresent the average maximum transmission power of cognitive user; In order to not affect the transfer of data of authorized user, the average interference power of every sub-channels also should be restricted, and namely the average interference power restrictive condition of subchannel i is wherein I _irepresent the interference power that in subchannel i, authorized user receives, represent the maximum average interference that authorized user can accept.

Multichannel efficiency Optimized model then based on cognitive radio can be expressed as:

$\underset{\mathrm{\τ},P^{\left(0\right)},P^{\left(1\right)}}{\min }\mathrm{\η}(\mathrm{\τ},P^{\left(0\right)},P^{\left(1\right)})=\frac{E(\mathrm{\τ},P^{\left(0\right)},P^{\left(1\right)})}{C(\mathrm{\τ},P^{\left(0\right)},P^{\left(1\right)})}=\frac{\[{\mathrm{MP}}_{sens}\mathrm{\τ}+\underset{i=1}{\overset{M}{\Σ}}(T-\mathrm{\τ})P_i\]}{E\[\underset{i=1}{\overset{M}{\Σ}}(T-\mathrm{\τ})C_i\]}---\left(1\right)$

Constraints is:

Efficiency η (τ, P ⁽⁰⁾, P ⁽¹⁾) represent that user often transmits the required energy consumed of a Bit data, i.e. energy efficiency, referred to as efficiency, wherein, E (τ, P ⁽⁰⁾, P ⁽¹⁾) represent the overall average energy of multichannel cognitive user, C (τ, P ⁽⁰⁾, P ⁽¹⁾) representing the average transmission rate of multichannel cognitive user, symbol E [] represents the mean value asked in square brackets, P ⁽¹⁾represent the overall transmission power of cognitive user under busy condition, P ⁽⁰⁾represent cognitive user overall transmission power in an idle state, P _sensrepresent the perception power of cognitive user.

The present invention is by being converted to its dual problem F (λ)=min{E (τ, P by above-mentioned efficiency Optimized model expression formula (1) ⁽⁰⁾, P ⁽¹⁾)-λ C (τ, P ⁽⁰⁾, P ⁽¹⁾) optimization, concrete optimization implementation is:

Step1: based on the frame transmission time T of Frame, arrange section search time of detecting period τ, concrete value is based on practical situations, in present embodiment, ST section is set for [0,0.5T], is separated into the test detecting period point τ that multiple interval is identical _test, in the present embodiment, each test detecting period point be spaced apart 0.05s, actual when using, can sets itself according to demand;

Step2: before current data to be transmitted frame transmission, aware services device is successively to each perception test time point τ _testcalculate preferred overall transmission power with preferred energy efficiency eta (τ, P ⁽⁰⁾, P ⁽¹⁾) ^*even given perception τ is perception test time point τ _test, perform step 201 ~ 204:

201: Two Variables parameter is set: λ _minand λ _max, λ _mininitial value be 0, λ _maxinitial value be set to be greater than 10^ (-10), in this embodiment, the initial value of λ 2 is 10^ (-6);

202: if λ _max-λ _min≤ ε, then perform step 204; Otherwise perform step 203, preset value ε is for being less than or equal to the positive number of 10^ (-10);

203: λ is set _mid=(λ _min+ λ _max)/2, call interior point method function f mincon (x, y, z) and calculate F (λ _mid) value,

If F is (λ _mid)≤0, then make λ _max=λ _mid, and perform step 202; If F is (λ _mid) > 0, then make λ _min=λ _mid, return step 202;

In interior point method function f mincon (x, y, z), x corresponding optimization aim min{E (τ, P ⁽⁰⁾, P ⁽¹⁾)-λ _midc (τ, P ⁽⁰⁾, P ⁽¹⁾), y represents the total mean power restrictive condition f of cognitive user M sub-channels ₀; Z represents the average interference power restrictive condition f of every sub-channels _i;

204: by repeated execution of steps 202 and 203, constantly approach λ _minand λ _maxvalue, work as λ _max-λ _minduring≤ε, obtain preferred λ ^*, its value is λ ^*=λ _min(in actual applications, because λ _minand λ _maxvalue approach very much, preferred λ ^*value also can get λ ^*=λ _max, or λ _minand λ _maxbetween count arbitrarily);

Based on preferred λ ^*, by formula F (λ)=min{E (τ, P ⁽⁰⁾, P ⁽¹⁾)-λ C (τ, P ⁽⁰⁾, P ⁽¹⁾) to P ⁽⁰⁾, P ⁽¹⁾cognitive user is at current test detecting period point τ to ask local derviation to draw _testtime preferred overall transmission power with and the efficiency formula according to formula (1) obtain with with corresponding energy efficiency η (τ, P ⁽⁰⁾, P ⁽¹⁾) ^*, and record and current test detecting period point τ _testcorresponding with η (τ, P ⁽⁰⁾, P ⁽¹⁾) ^*;

Step 3: get each perception test time point τ in repetition step 1 and 2 _testcorresponding preferred energy efficiency eta (τ, P ⁽⁰⁾, P ⁽¹⁾) ^*after, find out minimum preferred energy efficiency eta (τ, P ⁽⁰⁾, P ⁽¹⁾) ^*as optimum efficiency η (τ, P ⁽⁰⁾, P ⁽¹⁾) ^optimal, by the detecting period point τ corresponding to this optimum efficiency _test, preferred overall transmission power with in frame structure for current data to be transmitted frame, as its optimum detecting period, optimum allocation power, after the current data frame end of transmission, aware services device carries out perception and the optimization of a new round.

The above, be only the specific embodiment of the present invention, arbitrary feature disclosed in this specification, unless specifically stated otherwise, all can be replaced by other equivalences or the alternative features with similar object; Step in disclosed all features or all methods or process, except mutually exclusive feature and/or step, all can be combined in any way.

Claims (4)

1., based on a multi channel cognitive user efficiency optimization method, it is characterized in that, comprise the following steps:

Step 1: based on the frame transmission time T of Frame, arrange section search time of detecting period, is separated into the identical test detecting period point τ in multiple interval by section described search time _test;

Step 2: before current data to be transmitted frame transmission, aware services device is respectively to each test detecting period point τ _testcalculate preferred overall transmission power with preferred efficiency η (τ _test, P ⁽⁰⁾, P ⁽¹⁾) ^*:

201: Two Variables parameter is set: λ 1 and the initial value of λ 2, λ 1 be that the initial value of 0, λ 2 is greater than 10^ (-10);

202: judge whether λ 2 is less than or equal to preset value ε with the difference of λ 1, if so, then perform step 204; Otherwise perform step 203, described preset value ε is for being less than or equal to the positive number of 10^ (-10);

203: calculate F (λ by interior point method function f mincon (x, y, z) _mid) value, if F (λ _mid) be less than or equal to 0, then make λ 2 equal λ _mid, and perform step 202; If F is (λ _mid) be greater than 0, then make λ 1 equal λ _mid, and perform step 202;

Wherein λ _midrepresent the average of λ 1 and λ 2, F (λ _mid)=min{E (τ _test, P ⁽⁰⁾, P ⁽¹⁾)-λ _midc (τ _test, P ⁽⁰⁾, P ⁽¹⁾);

In described interior point method function f mincon (x, y, z),

The corresponding optimization aim min{E (τ of x _test, P ⁽⁰⁾, P ⁽¹⁾)-λ _midc (τ _test, P ⁽⁰⁾, P ⁽¹⁾), the overall average energy of multichannel cognitive user $E({\mathrm{\τ}}_{test},P^{\left(0\right)},P^{\left(1\right)})=E\[{\mathrm{MP}}_{sens}{\mathrm{\τ}}_{test}+\underset{i=1}{\overset{M}{\Σ}}(T-{\mathrm{\τ}}_{test})P_i\],$ The average transmission rate of multichannel cognitive user $C({\mathrm{\τ}}_{test},P^{\left(0\right)},P^{\left(1\right)})=E\[\underset{i=1}{\overset{M}{\Σ}}(T-{\mathrm{\τ}}_{test})C_i\];$ Symbol E [] represents averaged, P ⁽¹⁾represent the overall transmission power of cognitive user under busy condition, P ⁽⁰⁾represent cognitive user overall transmission power in an idle state, P _sensrepresent the perception power of cognitive user, M represents the number of subchannels of cognitive user, P _i=α _{0, i}p ⁽⁰⁾+ α _{1, i}p ⁽¹⁾+ β _{0, i}p ⁽⁰⁾+ β _{1, i}p ⁽¹⁾represent the average transmission gross power of subchannel i, C _i=α _{0, i}r _{00, i}+ α _{1, i}r _{01, i}+ β _{0, i}r _{10, i}+ β _{1, i}r _{11, i}represent the average transmission rate of subchannel i, wherein α _{0, i}, α _{1, i}, β _{0, i}, β _{1, i}represent that channel i is the probability of detected state a, b, c, d, r _{00, i}, r _{01, i}, r _{10, i}, r _{11, i}represent transmission rate during detected state a, b, c, d of respective channels i, described detected state a, b, c, d are followed successively by: detected state a, and cognitive user and authorized user are idle condition; Detected state b, cognitive user is idle condition and authorized user is busy condition; Detected state c, cognitive user is busy condition and authorized user is idle condition; Detected state d, cognitive user and authorized user are busy condition;

Y represents the total mean power restrictive condition of cognitive user M sub-channels wherein P _avrepresent the average maximum transmission power of cognitive user;

Z represents the average interference power restrictive condition of every sub-channels wherein I _irepresent the interference power that in subchannel i, authorized user receives, represent the maximum average interference that authorized user can accept;

204: parameters λ ^*, described λ ^*value be λ 1 ~ λ 2, and optimize formula F (λ)=min{E (τ based on efficiency _test, P ⁽⁰⁾, P ⁽¹⁾)-λ C (τ _test, P ⁽⁰⁾, P ⁽¹⁾), the value of getting variable λ is parameter lambda ^*time corresponding overall transmission power P ⁽¹⁾and P ⁽⁰⁾for current test detecting period point τ _testpreferred overall transmission power with and according to efficiency formula calculate and described preferred overall transmission power with corresponding preferred efficiency

Step 3: at each perception test time point τ based on described step 1 and 2 acquisitions _testcorresponding preferred energy efficiency eta (τ, P ⁽⁰⁾, P ⁽¹⁾) ^*in, get minimum preferred energy efficiency eta (τ, P ⁽⁰⁾, P ⁽¹⁾) ^*corresponding perception test time point, preferably overall transmission power with for optimum detecting period, the optimum allocation power of current data to be transmitted frame.

2. the method for claim 1, is characterized in that, each perception test time point τ _testthe time interval is 0.1ms ~ 0.5ms.

3. the method for claim 1, is characterized in that, described search time, section was [0, kT], and the span of k is 0.4 ~ 0.6.

4. the method for claim 1, is characterized in that, in described step 201, the initial value of λ 2 is 10^ (-6).