CN104125024A - Channel detecting method for optimal time approach of cognitive radio - Google Patents
Channel detecting method for optimal time approach of cognitive radio Download PDFInfo
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Abstract
The invention relates to a channel detecting method for optimal time approach of cognitive radio and belongs to the technical field of communication channel detection. According to the channel detecting method for optimal time approach of the cognitive radio, firstly, a broadcast channel obtains channel allocation information through time slot decoding according to channel allocation frames, a cognitive user detects allocated channels one by one according to a frequency band detection time sequence, and performance index quantity calculation is concurrently performed on all detected available idle channels; then the cognitive user sequentially and continuously corrects the detection time sequence according to correction factors to obtain a new channel detection time sequence, then the new channel detection time sequence is used for detecting the channels, and the performance index quantity calculation is concurrently performed on all detected available idle channels; finally, an optimal performance index quantity obtained in the second step is compared with an optimal performance index quantity obtained in the first step, and the circulation is sequentially performed till the obtained performance index quantity is converged. By means of the channel detecting method for optimal time approach of the cognitive radio, the problem of low channel utilizing ratio can be effectively solved.
Description
Technical field
The present invention relates to a kind of cognitive radio time approaches optimum channel detection method, belongs to communication channel detection technique field.
Background technology
Along with the development of wireless communication technology, people have also had deep understanding to radio.Distributed unitedly by government due to radio spectrum resources, existing channel is more and more crowded, but present many channels can not whole day take, and the most of the time is all idle, exist like this waste of resource.
In order to utilize more efficiently channel resource, carried out based on channel resource allocation and optimized cognitive radio technology.It detects channel successively by time-division slot, not occupied channel-aware out, distributes to user and carry out the transmission of data after optimization.
In view of channel resource more nervous today, if the transmission data that can use and can be very fast to other users the channel allocation of these idle periods, the utilance that has just improved resource greatly, has therefore proposed a kind of cognitive radio time to approach optimum channel detection method.The method can find optimum channel idle detection time by the adaptive correction factor and the concurrent operation that repeatedly circulates, so just greatly shorten the detection time of channel, thereby increase the data transmission period of channel, finally made the data volume of transmission obtain significantly increasing.
Summary of the invention
Technical problem to be solved by this invention be can be very fast in Channel Detection process the idle channel that can transmit data that finds, and make performance index value reach maximum, the Channel Detection time will approach optimum problem, provides a kind of cognitive radio time to approach optimum channel detection method.
Technical scheme of the present invention is: a kind of cognitive radio time approaches optimum channel detection method, and first broadcast channel, according to channel allocation frame, obtains channel allocation information through time slot decoding, and cognitive user is according to frequency range sequence detection time
t _ check the channel having distributed is detected one by one, more concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount, then find optimum performance index amount by the numerical value in more performance index amount of recycle ratio; Then cognitive user is according to modifying factor
t _
next =
kT _ check +
bN 0constantly revise successively detection time sequence and obtain new Channel Detection time series, then use new Channel Detection time series to detect channel, concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount again, thereby find optimum performance index amount by the numerical value in more performance index amount of recycle ratio; Finally the optimum performance index amount obtaining specifically and the last optimum performance index amount obtaining are compared, circulation successively, until the performance index amount of taking out while reaching convergence, realizes and reaches the Channel Detection time and approach optimum; Wherein,
t _ check represent initialization sequence detection time,
t _
next represent sequence detection time after upgrading,
kfor correction factor,
and
,
for revising offset coefficient,
n 0for a certain constant.
The concrete steps of described method are as follows:
Step1, broadcast channel source adopt channel resource allocation frame mapped mode to resolve and obtain two-dimensional vector channel allocation information matrix
wT gs×
gp :
In formula:
tT gs represent the
gsindividual user's Channel Detection sequence,
gsrepresent Channel Detection number of users,
gprepresent the channel number of distributing,
t gs×
gp represent the
gsindividual user is to
gpindividual channel detects;
Step2, according to the interval random time slot of determining of different frequency range, then determine frequency range sequence detection time by the situation that takies of small time slot in time slot
t _ check =[
t _1
......
t _ i ]; Wherein,
iget positive integer,
t _ i represent the of Channel Detection
iindividual detection time;
Step3, Channel Detection: cognitive user is according to Channel Detection time series
t _ check and Rayleigh channel module is to assignment information matrix
wT gs×
gp carry out channel idle detection, all spendable idle channel detecting is stored into
w _ channel in matrix; Concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount and the multiple performance index values that calculate are stored into simultaneously
r _ ttl in; Then by recycle ratio
r _ ttl in numerical value find optimum performance index amount to be
maxR _ ttl , and
maxR _ ttl store into
z _ max in, will
maxR _ ttl corresponding detection time
t _ i store into
p _ fir in; Wherein,
w _ channel represent available channel matrix,
r _ ttl represent performance index matrix,
maxR _ ttl represent optimum performance index amount,
z _ max represent optimal performance array,
p _ fir represent optimal check time array;
Step4, adaptive factor upgrade sequence detection time: according to the operation result in step Step3, cognitive user is used the adaptive correction factor
t _
next =
kT _ check +
bN 0to the last time
t _ check after sequence correction, obtain new sequence detection time detection time
t _
next , cognitive user is again according to revised
t _
next channel is detected, repeating step Step3, and this is obtained
maxR _ ttl store into the last time in step Step3
z _ max in value compare, take out maximum
maxR _ ttl replace
z _ max in value, and this maximum
maxR _ ttl corresponding
t _ i store into
p _ fir in, for cycle calculations;
Step5, loop convergence: repeat above-mentioned step Step3, step Step4, cognitive user is constantly carried out repeated detection according to the Channel Detection time series after upgrading to channel, relatively obtain optimum performance index by cycle calculations, and find the optimum Channel Detection time: when
z _ max middle storage
maxR _ ttl when value reaches convergence, corresponding
p _ fir in detection time
t _ i it is optimum that value reaches, optimum by obtaining
t _ i approach optimum value detection time as channel idle.
Described performance index amount is
lsecondary channel information obtains the transfer of data index amount of available channel after detecting:
; Wherein,
represent message transmission rate,
trepresent the Channel Detection cycle,
lrepresent Channel Detection number of times,
t _ i represent the of Channel Detection
individual detection time.
Operation principle of the present invention is:
Step 1: set up Channel Detection time series and approach optimal models and optimization aim.
Channel Detection time series is approached optimal models, and to be broadcast channel obtain channel allocation matrix according to channel allocation frame through time slot decoding, cognitive user according to detection time sequence the channel having distributed is detected one by one, and constantly adopt modifying factor
t _
next =
kT _ check +
bN 0to detection time sequence upgrade, cognitive user detects channel according to sequence detection time after upgrading again, earliest detection is set up communication to idle channel, makes to detect that available channel and throughput reach under maximal condition, and the Channel Detection time reaches minimum.Wherein,
t _ check represent initialization sequence detection time,
t _
next represent sequence detection time after upgrading,
t _
next =
kT _ check +
bN 0represent sequence modifying factor detection time,
kfor correction factor,
and
,
for revising offset coefficient,
n 0for a certain constant.
Step 2: the calculating of performance index amount.
lafter secondary channel information detects, the function that has obtained the transfer of data index amount of available channel is:
, therefore
when optimum,
optimum, thus the Channel Detection time approach optimum.Wherein,
trepresent the Channel Detection cycle,
represent message transmission rate and
a constant,
t _ i represent (of a Channel Detection concrete detection time
individual detection time),
lrepresent Channel Detection number of times,
represent channel data transmission index amount.
Step 3: the expression of channel allocation frame.
Channel allocation frame is to adopt channel resource allocation frame mapped mode 1 in the time of allocation of channel resources) fixed resource mapped mode carries out resource searching on Physical Downlink Shared Channel PDSCH; 2) frequency-hopping resource mapped mode, carries out resource searching in the E-PDCCH on PDSCH.In search procedure, can come markup resources position with CSS, obtain channel allocation information so that channel sources can be resolved fast.
The two-dimensional vector channel allocation matrix that adopts channel resource allocation frame mapped mode to resolve
wT gs×
gp ,
In formula:
wT gs×
gp represent the two-dimensional vector channel allocation information of channel;
tT gs represent the
gsindividual user's Channel Detection sequence;
gsrepresent Channel Detection number of users;
gprepresent the channel number of distributing;
t gs×
gp represent the
gsindividual user is to
gpindividual channel detects;
Step 4: the initialization of frequency range sequence detection time array.
According to the interval random time slot of determining of different frequency ranges, then determine frequency range sequence detection time array according to the situation that takies of small time slot in time slot
t _ check ,
t _ check =[
t _1
......
t _ i ], wherein,
t _ check represent time series set,
iget positive integer,
t _ i represent the of Channel Detection
iindividual detection time;
Step 5: Channel Detection and parallel computation
Cognitive user is according to Channel Detection time series
t _ check carry out the channel allocation matrix that broadcast channel is issued
wT gs×
gp carry out channel idle detection, the all spendable free channel information that cognitive user is detected stores, use the method for parallel computation to carry out the calculating of performance index amount to the idle channel detecting, then obtain optimum performance index amount and optimum corresponding detection time of performance index amount by recycle ratio.
Under the effect of sequence detection time, each user can produce multiple idle channels to Channel Detection, in order to calculate the transfer of data figureofmerit of channel, each data that obtain that detect are all stored, finally carry out again index calculating, that has just improved the complexity of calculating and the precision of calculating greatly, is also difficult to obtain the optimum Channel Detection time; In the present invention, adopt the mode of parallel computation, the data that produce are each time packaged as a set and carry out data processing at once, the optimal data obtaining is stored in memory space, in time detecting sequence more under news, again process the data that obtain, the optimal data obtaining and the last preferred channels that is stored in memory space are compared detection time, store approaching the optimum Channel Detection time memory space having emptied into, constantly circulation, finally obtains the optimum Channel Detection time successively.
Step 6: the adaptive correction factor constantly learns to upgrade sequence detection time.
Cognitive user is used the adaptive correction factor
t _
next =
kT _ check +
bN 0constantly upgrade and after sequence, obtain new sequence detection time detection time
t _
next , cognitive user is according to new
t _
next channel is detected again.
In Channel Detection process, modifying factor is comparatively obvious on the impact of algorithm performance on the renewal of sequence detection time.First, do not upgrading in Channel Detection seasonal effect in time series situation, can find than Channel Detection time preferably by detecting the algorithm of available channel, but that be not the optimum Channel Detection time; Secondly, simple renewal Channel Detection time series, from algorithm, is to find an optimum Channel Detection time, but has very large fluctuation, and algorithm is easy to be absorbed in local optimum.In view of above deficiency, the present invention proposes and use the adaptive correction factor to regulate Channel Detection seasonal effect in time series strategy, this strategy can make algorithm obtain on the whole approaching the optimum Channel Detection time.
Step 7: constantly make Channel Detection time optimization.
Cognitive user constantly adopts the Channel Detection time series of renewal to detect the channel of channel allocation matrix, and the used channel detecting is constantly carried out to the computing of channel data transmission index amount, finally obtains approaching the optimum Channel Detection time.
Step 8: judge whether to export optimum results.
This algorithm makes performance index amount reach convergence, and the performance index amount obtaining meets
(
get arbitrarily small positive number) time, reach optimum detection time in corresponding optimal check time array, at this moment algorithm finishes, and has found preferred channels detection time; Otherwise, continue computing.Wherein, in formula
xrepresent algorithm cycle-index;
represent that algorithm cycle-index is repeatedly infinite; Lim represents to ask limit symbol;
represent the end value of the performance index amount obtaining in algorithm;
represent the end value of approaching in algorithm;
represent arbitrarily small positive number.
The invention has the beneficial effects as follows: proposed channel performance index optimum, the Channel Detection time series of Channel Detection minimal time is approached optimal models and the parallel iteration algorithm based on the adaptive correction factor, make in communication channel detects, cognitive user is clear accurately to the expression of Channel Detection process, revises alternative manner rationally effective; Adopt parallel calculating method that the complexity of calculating is significantly reduced; Design the improvement strategy with adaptive correction factor ability, can effectively overcome and be difficult to find the preferred channels difficult problem of detection time.Proposed by the invention approach optimum channel detection method based on auto-adaptive time and can effectively solve the problem that channel utilization is low.
Brief description of the drawings
Fig. 1 is the initialized flow chart of numerical value of realizing of the present invention;
Fig. 2 is that the resource of channel allocation frame of the present invention is distributed schematic diagram;
Fig. 3 is the interval time slot search schematic diagram of frequency range of the present invention;
Fig. 4 is the initialized flow chart of numerical value of realizing of the present invention;
Fig. 5 is the adaptive correction factor process of feedback figure that realizes of the present invention;
Fig. 6 is the theoretical value of embodiment 2 and the result schematic diagram of simulation value in the present invention;
Fig. 7 is the theoretical value of embodiment 3 and the result schematic diagram of simulation value in the present invention.
Embodiment
Embodiment 1: as shown in Fig. 1-7, a kind of cognitive radio time approaches optimum channel detection method, first broadcast channel, according to channel allocation frame, obtains channel allocation information through time slot decoding, and cognitive user is according to frequency range sequence detection time
t _ check the channel having distributed is detected one by one, more concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount, then find optimum performance index amount by the numerical value in more performance index amount of recycle ratio; Then cognitive user is according to modifying factor
t _
next =
kT _ check +
bN 0constantly revise successively detection time sequence and obtain new Channel Detection time series, then use new Channel Detection time series to detect channel, concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount again, thereby find optimum performance index amount by the numerical value in more performance index amount of recycle ratio; Finally the optimum performance index amount obtaining specifically and the last optimum performance index amount obtaining are compared, circulation successively, until the performance index amount of taking out while reaching convergence, realizes and reaches the Channel Detection time and approach optimum; Wherein,
t _ check represent initialization sequence detection time,
t _
next represent sequence detection time after upgrading,
kfor correction factor,
and
,
for revising offset coefficient,
n 0for a certain constant.
The concrete steps of described method are as follows:
Step1, broadcast channel source adopt channel resource allocation frame mapped mode to resolve and obtain two-dimensional vector channel allocation information matrix
wT gs×
gp :
In formula:
tT gs represent the
gsindividual user's Channel Detection sequence,
gsrepresent Channel Detection number of users,
gprepresent the channel number of distributing,
t gs×
gp represent the
gsindividual user is to
gpindividual channel detects;
Step2, according to the interval random time slot of determining of different frequency range, then determine frequency range sequence detection time by the situation that takies of small time slot in time slot
t _ check =[
t _1
......
t _ i ]; Wherein,
iget positive integer,
t _ i represent the of Channel Detection
iindividual detection time;
Step3, Channel Detection: cognitive user is according to Channel Detection time series
t _ check and Rayleigh channel module is to assignment information matrix
wT gs×
gp carry out channel idle detection, all spendable idle channel detecting is stored into
w _ channel in matrix; Concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount and the multiple performance index values that calculate are stored into simultaneously
r _ ttl in; Then by recycle ratio
r _ ttl in numerical value find optimum performance index amount to be
maxR _ ttl , and
maxR _ ttl store into
z _ max in, will
maxR _ ttl corresponding detection time
t _ i store into
p _ fir in; Wherein,
w _ channel represent available channel matrix,
r _ ttl represent performance index matrix,
maxR _ ttl represent optimum performance index amount,
z _ max represent optimal performance array,
p _ fir represent optimal check time array;
Step4, adaptive factor upgrade sequence detection time: according to the operation result in step Step3, cognitive user is used the adaptive correction factor
t _
next =
kT _ check +
bN 0to the last time
t _ check after sequence correction, obtain new sequence detection time detection time
t _
next , cognitive user is again according to revised
t _
next channel is detected, repeating step Step3, and this is obtained
maxR _ ttl store into the last time in step Step3
z _ max in value compare, take out maximum
maxR _ ttl replace
z _ max in value, and this maximum
maxR _ ttl corresponding
t _ i store into
p _ fir in, for cycle calculations;
Step5, loop convergence: repeat above-mentioned step Step3, step Step4, cognitive user is constantly carried out repeated detection according to the Channel Detection time series after upgrading to channel, relatively obtain optimum performance index by cycle calculations, and find the optimum Channel Detection time: when
z _ max middle storage
maxR _ ttl when value reaches convergence, corresponding
p _ fir in detection time
t _ i it is optimum that value reaches, optimum by obtaining
t _ i approach optimum value detection time as channel idle.
Described performance index amount is
lsecondary channel information obtains the transfer of data index amount of available channel after detecting:
; Wherein,
represent message transmission rate,
trepresent the Channel Detection cycle,
lrepresent Channel Detection number of times,
t _ i represent the of Channel Detection
individual detection time.
Embodiment 2: as shown in Fig. 1-7, a kind of cognitive radio time approaches optimum channel detection method, first broadcast channel, according to channel allocation frame, obtains channel allocation information through time slot decoding, and cognitive user is according to frequency range sequence detection time
t _ check the channel having distributed is detected one by one, more concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount, then find optimum performance index amount by the numerical value in more performance index amount of recycle ratio; Then cognitive user is according to modifying factor
t _
next =
kT _ check +
bN 0constantly revise successively detection time sequence and obtain new Channel Detection time series, then use new Channel Detection time series to detect channel, concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount again, thereby find optimum performance index amount by the numerical value in more performance index amount of recycle ratio; Finally the optimum performance index amount obtaining specifically and the last optimum performance index amount obtaining are compared, circulation successively, until the performance index amount of taking out while reaching convergence, realizes and reaches the Channel Detection time and approach optimum; Wherein,
t _ check represent initialization sequence detection time,
t _
next represent sequence detection time after upgrading,
kfor correction factor,
and
,
for revising offset coefficient,
n 0for a certain constant.
Design parameter is designed to:
k=0.8,
b=1,
n 0=0,
t _
next =0.8 ×
t _ check + 1 × 0;
The concrete steps of described method are as follows:
Step1, broadcast channel source adopt channel resource allocation frame mapped mode (as shown in Figure 1) to resolve and obtain two-dimensional vector channel allocation information matrix
wT gs×
gp :
In formula:
tT gs represent the
gsindividual user's Channel Detection sequence,
gsrepresent Channel Detection number of users,
gprepresent the channel number of distributing,
t gs×
gp represent the
gsindividual user is to
gpindividual channel detects;
Design parameter is designed to:
gs=
gp=2, obtain
;
Step2, according to the interval random time slot of determining of different frequency range, then determine frequency range sequence detection time by the situation that takies (as shown in Figure 2) of small time slot in time slot
t _ check =[
t _1
......
t _ i ]; Wherein,
iget positive integer,
t _ i represent the of Channel Detection
iindividual detection time;
Design parameter design is as follows:
;
Step3, Channel Detection (as shown in Figure 4): cognitive user is according to Channel Detection time series
and Rayleigh channel module is to assignment information matrix
carry out channel idle detection, all spendable idle channel detecting is stored into
w _ channel in matrix::
time, do not find available idle channel;
t _ i , obtain channel at=0.8 o'clock
, because cognitive user 1 and cognitive user 2 all detect available channel No. 1, produced collision, therefore this channel
cannot use;
t _ i =0.6,0.7 o'clock, obtain available channel and be respectively
, then use parallel calculating method to the idle channel detecting
carry out performance index amount
(wherein, the Channel Detection cycle
t=2s, message transmission rate
,
t _ i represent the of Channel Detection
iindividual detection time, Channel Detection number of times
l=2) calculate, by the multiple performance index value storage obtaining
, then by recycle ratio compared with 2 times
in value obtain optimum performance index amount and be
maxR _ ttl =0.4, and obtain
maxR _ ttl the detection time of=0.4 correspondence
t _ i =0.6;
Step4, adaptive factor upgrade sequence detection time (as shown in Figure 5): according to the operation result in step Step3, cognitive user is used the adaptive correction factor
t _
next =0.8 ×
t _ check + 1 × 0 pair last
after sequence correction, obtain new sequence detection time detection time
, cognitive user is again according to revised
t _
next channel is detected:
Sequence detection time according to Rayleigh channel modular simulation and after upgrading
t _
next obtain channel detection result, that is:
time, do not find available idle channel;
time, obtain channel and be respectively
, but now cognitive user 1 and 2 all finds same available channel, has produced collision, therefore channel
with
all unavailable; When
time, obtain available channel and be respectively
, then use parallel calculating method to the idle channel detecting
,
carry out the calculating of performance index amount, obtain the multiple performance index after upgrading
, then by recycle ratio compared with 2 performance index amounts
in value obtain optimum performance index amount and be
maxR _ ttl =0.52, and obtain
maxR _ ttl the detection time of=0.52 correspondence
t _ i =0.48; This obtains
maxR _ ttl =0.52 with last
maxR _ ttl =0.4 compares, taking-up maximum
maxR _ ttl =0.52, and this maximum
maxR _ ttl corresponding
t _ i value is taken out,
t _ i =0.48.
Step5, loop convergence: repeat above-mentioned step Step3, step Step4, cognitive user reuses modifying factor correction and obtains new sequence detection time
channel is detected, obtain available channel and be
, calculation of performance indicators amount is
, by relatively obtain for 2 times optimum performance index amount be 0.448,0.448 with on optimal value 0.52 once compare once, obtaining optimum performance index amount is 0.52, and be 0.48 0.52 corresponding detection time.
After computing, know, this algorithm makes
maxR _ ttl reach convergence at=0.52 o'clock, by corresponding detection time
t _ i =0.48 takes out, and at this moment algorithm finishes, and finally obtains channel idle and approaches optimum value detection time
t _ i =0.48.
Fig. 6 has provided the theoretical value of the Channel Detection time of channel data transmission index amount under optimal situation according to Shannon's theorems; Foundation
channel allocation matrix and modifying factor
t _
next =0.8 ×
t _ check + 1 × 0, emulation under actual conditions, obtains simulation value.Between theoretical value and simulation value, there is a certain distance as we can see from the figure, but in allowed band.Simulation result demonstration in figure, when performance index amount (0.52) reaches maximum, it is 0.48 that the Channel Detection time approaches optimum.
Embodiment 3: as shown in Fig. 1-7, a kind of cognitive radio time approaches optimum channel detection method, first broadcast channel, according to channel allocation frame, obtains channel allocation information through time slot decoding, and cognitive user is according to frequency range sequence detection time
t _ check the channel having distributed is detected one by one, more concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount, then find optimum performance index amount by the numerical value in more performance index amount of recycle ratio; Then cognitive user is according to modifying factor
t _
next =
kT _ check +
bN 0constantly revise successively detection time sequence and obtain new Channel Detection time series, then use new Channel Detection time series to detect channel, concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount again, thereby find optimum performance index amount by the numerical value in more performance index amount of recycle ratio; Finally the optimum performance index amount obtaining specifically and the last optimum performance index amount obtaining are compared, circulation successively, until the performance index amount of taking out while reaching convergence, realizes and reaches the Channel Detection time and approach optimum; Wherein,
t _ check represent initialization sequence detection time,
t _
next represent sequence detection time after upgrading,
kfor correction factor,
and
,
for revising offset coefficient,
n 0for a certain constant.
Design parameter is designed to:
k=0.85,
b=2,
n 0=0.01,
t _
next =0.85 ×
t _ check + 2 × 0.01;
The concrete steps of described method are as follows:
Step1, broadcast channel source adopt channel resource allocation frame mapped mode (as shown in Figure 1) to resolve and obtain two-dimensional vector channel allocation information matrix
wT gs×
gp :
In formula:
tT gs represent the
gsindividual user's Channel Detection sequence,
gsrepresent Channel Detection number of users,
gprepresent the channel number of distributing,
t gs×
gp represent the
gsindividual user is to
gpindividual channel detects;
Design parameter is designed to:
gs=3,
gp=5, obtain
;
Step2, according to the interval random time slot of determining of different frequency range, then determine frequency range sequence detection time by the situation that takies (as shown in Figure 2) of small time slot in time slot
t _ check =[
t _1
......
t _ i ]; Wherein,
iget positive integer,
t _ i represent the of Channel Detection
iindividual detection time;
Design parameter design is as follows:
;
Step3, Channel Detection (as shown in Figure 4): cognitive user is according to Channel Detection time series
and Rayleigh channel module is to assignment information matrix
carry out channel idle detection, all spendable idle channel detecting is stored into
w _ channel in matrix::
time, do not find available idle channel;
time, obtain available channel and be respectively
,
then use parallel calculating method to the idle channel detecting
,
carry out performance index amount
(wherein, the Channel Detection cycle
t=4s, message transmission rate
,
t _ i represent the of Channel Detection
iindividual detection time, Channel Detection number of times
l=6) calculate, the multiple performance index values that obtain are stored into
, then by recycle ratio compared with 6 times
in value obtain optimum performance index amount and be
maxR _ ttl =0.53, and obtain
maxR _ ttl the detection time of=0.53 correspondence
t _ i =0.49;
Step4, adaptive factor upgrade sequence detection time (as shown in Figure 5): according to the operation result in step Step3, cognitive user is used the adaptive correction factor
t _
next =0.85 ×
t _ check + 2 × 0.01 pair last
after sequence correction, obtain new sequence detection time detection time
, cognitive user is again according to revised
t _
next channel is detected:
Sequence detection time according to Rayleigh channel modular simulation and after upgrading
t _
next obtain channel detection result, that is:
time, do not find available idle channel;
time, obtain idle channel and be respectively
,
; Wherein,
with
in cognitive user all find same channel, produced collision, therefore
with
all unavailable, only have
, and
in channel can use, then use parallel calculating method to the idle channel detecting
, and
carry out performance index amount
(wherein, the Channel Detection cycle
t=4s, message transmission rate
,
t _ i represent the of Channel Detection
iindividual detection time, Channel Detection number of times
l=6) calculate, by the multiple performance index value storage obtaining
, then by recycle ratio compared with 3 performance index amounts
in value obtain optimum performance index amount and be
maxR _ ttl =0.563, and obtain
maxR _ ttl the detection time of=0.563 correspondence
t _ i =0.479; This obtains
maxR _ ttl =0.563 with last
maxR _ ttl =0.53 compares, taking-up maximum
maxR _ ttl =0.563, and this maximum
maxR _ ttl corresponding
t _ i value is taken out,
t _ i =0.479.
Step5, loop convergence: repeat above-mentioned step Step3, step Step4, cognitive user is through repeatedly being used modifying factor pair
correction obtains new sequence detection time
channel is detected, when
time, detect that idle channel is respectively
,
,
,
, but
detected by multiple users, channel has produced collision, therefore channel simultaneously
all be not useable for transfer of data, only have
time be available channel, calculation of performance indicators amount is
, by relatively obtain for 3 times optimum performance index amount be 0.5885,0.5885 with on optimal value 0.563 once compare once, obtaining optimum performance index amount is 0.5885, and be 0.4705 0.5885 corresponding detection time.
Through repeatedly knowing after computing, this algorithm makes
maxR _ ttl reach convergence at=0.5885 o'clock,
therefore 0.5885 is final convergency value, now by corresponding detection time
t _ i =0.4705 takes out, and at this moment algorithm finishes, and finally obtains channel idle and approaches optimum value detection time
t _ i =0.4705.
Fig. 7 has provided the theoretical value of the Channel Detection time of channel data transmission index amount under optimal situation according to Shannon's theorems; Foundation
channel allocation matrix and modifying factor
t _
next =0.85 ×
t _ check + 2 × 0.01, emulation under actual conditions, obtains simulation value.Between theoretical value and simulation value, there is a certain distance as we can see from the figure, but in allowed band.Simulation result demonstration in figure, when performance index amount (0.5885) reaches maximum, it is 0.4705 that the Channel Detection time approaches optimum.
Fig. 6 and Fig. 7 know: the theoretical value that has provided the Channel Detection time of channel data transmission index amount under optimal situation according to Shannon's theorems; Reach under maximal condition in transfer of data index amount according to actual situation, provided simulation value.Between theoretical value and simulation value, there is a certain distance as we can see from the figure, but in allowed band.In the time just starting to detect channel, there is not volume of transmitted data in theoretical calculating and actual emulation, therefore performance index value is 0.Known by figure, available channel in theory takes the lead in detecting, and actual emulation detects that the time of idle channel is longer than theoretic detection time, but both there is the trend that performance index value increases progressively, in the time reaching certain Channel Detection time value, all there is optimum performance index amount in theoretical calculating and actual emulation.But in the time reaching optimum performance index amount, the theoretical Channel Detection time is less than the actual Channel Detection time, and theoretical optimal performance index value is greater than actual optimal performance index value.Subsequently both performance index amounts all sharply drop to 0.Why actual emulation value and theoretical value can create a difference, and are because theoretical value is to carry out under desirable condition, and in actual emulation value, have the interference of switching, and the factor such as abnormal of user during to Channel Detection causes.But in general, in the cognitive radio that the present invention proposes, the Channel Detection time approaches the amendment scheme that optimum method adopts self adaptation to feed back, obviously be better than traditional method, find the optimum Channel Detection time, data transmission period under same period is increased, finally obtain more volume of transmitted data.
By reference to the accompanying drawings the specific embodiment of the present invention is explained in detail above, but the present invention is not limited to above-mentioned execution mode, in the ken possessing those of ordinary skill in the art, can also under the prerequisite that does not depart from aim of the present invention, make various variations.
Claims (3)
1. the cognitive radio time approaches an optimum channel detection method, it is characterized in that: first broadcast channel, according to channel allocation frame, obtains channel allocation information through time slot decoding, and cognitive user is according to frequency range sequence detection time
t _ check the channel having distributed is detected one by one, more concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount, then find optimum performance index amount by the numerical value in more performance index amount of recycle ratio; Then cognitive user is according to modifying factor
t _
next =
kT _ check +
bN 0constantly revise successively detection time sequence and obtain new Channel Detection time series, then use new Channel Detection time series to detect channel, concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount again, thereby find optimum performance index amount by the numerical value in more performance index amount of recycle ratio; Finally the optimum performance index amount obtaining specifically and the last optimum performance index amount obtaining are compared, circulation successively, until the performance index amount of taking out while reaching convergence, realizes and reaches the Channel Detection time and approach optimum; Wherein,
t _ check represent initialization sequence detection time,
t _
next represent sequence detection time after upgrading,
kfor correction factor,
and
,
for revising offset coefficient,
n 0for a certain constant.
2. the cognitive radio time according to claim 1 approaches optimum channel detection method, it is characterized in that: the concrete steps of described method are as follows:
Step1, broadcast channel source adopt channel resource allocation frame mapped mode to resolve and obtain two-dimensional vector channel allocation information matrix
wT gs×
gp :
In formula:
tT gs represent the
gsindividual user's Channel Detection sequence,
gsrepresent Channel Detection number of users,
gprepresent the channel number of distributing,
t gs×
gp represent the
gsindividual user is to
gpindividual channel detects;
Step2, according to the interval random time slot of determining of different frequency range, then determine frequency range sequence detection time by the situation that takies of small time slot in time slot
t _ check =[
t _1
......
t _ i ]; Wherein,
iget positive integer,
t _ i represent the of Channel Detection
iindividual detection time;
Step3, Channel Detection: cognitive user is according to Channel Detection time series
t _ check and Rayleigh channel module is to assignment information matrix
wT gs×
gp carry out channel idle detection, all spendable idle channel detecting is stored into
w _ channel in matrix; Concurrently all spendable idle channel detecting is carried out to the calculating of performance index amount and the multiple performance index values that calculate are stored into simultaneously
r _ ttl in; Then by recycle ratio
r _ ttl in numerical value find optimum performance index amount to be
maxR _ ttl , and
maxR _ ttl store into
z _ max in, will
maxR _ ttl corresponding detection time
t _ i store into
p _ fir in; Wherein,
w _ channel represent available channel matrix,
r _ ttl represent performance index matrix,
maxR _ ttl represent optimum performance index amount,
z _ max represent optimal performance array,
p _ fir represent optimal check time array;
Step4, adaptive factor upgrade sequence detection time: according to the operation result in step Step3, cognitive user is used the adaptive correction factor
t _
next =
kT _ check +
bN 0to the last time
t _ check after sequence correction, obtain new sequence detection time detection time
t _
next , cognitive user is again according to revised
t _
next channel is detected, repeating step Step3, and this is obtained
maxR _ ttl store into the last time in step Step3
z _ max in value compare, take out maximum
maxR _ ttl replace
z _ max in value, and this maximum
maxR _ ttl corresponding
t _ i store into
p _ fir in, for cycle calculations;
Step5, loop convergence: repeat above-mentioned step Step3, step Step4, cognitive user is constantly carried out repeated detection according to the Channel Detection time series after upgrading to channel, relatively obtain optimum performance index by cycle calculations, and find the optimum Channel Detection time: when
z _ max middle storage
maxR _ ttl when value reaches convergence, corresponding
p _ fir in detection time
t _ i it is optimum that value reaches, optimum by obtaining
t _ i approach optimum value detection time as channel idle.
3. the cognitive radio time according to claim 1 and 2 approaches optimum channel detection method, it is characterized in that: described performance index amount is
lsecondary channel information obtains the transfer of data index amount of available channel after detecting:
; Wherein,
represent message transmission rate,
trepresent the Channel Detection cycle,
lrepresent Channel Detection number of times,
t _ i represent the of Channel Detection
individual detection time.
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| CN104994509A (en) * | 2015-05-07 | 2015-10-21 | 昆明理工大学 | Channel random requisition method applied to cognitive radio |
| CN114006864A (en) * | 2020-12-23 | 2022-02-01 | 技象科技(浙江)有限公司 | Channel scheduling method, device, system and storage medium based on time equalization |
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