A kind of double-layer lap of minimum power is for OFDM Subcarrier Allocation Algorithm
Technical field
The invention belongs to wireless communication fields, specifically, being related to a kind of transmission minimum power that can make base station
OFDM Subcarrier Allocation Algorithm.
Background technique
Quick with various intelligent terminals is popularized, and the demand growth of wireless traffic is rapid, the energy of wireless communication industry
Consumption increases at an amazing speed.From the point of view of the double angle of environmental protection and economic development, energy efficiency is improved, reduces network
Energy consumption, it has also become following mobile cellular network designs question of common concern.
In order to meet the needs of users, conventional cellular network is usually designed according to the peak value of cell capacity.At night
Administrative Area, the residential block on daytime, most network is seldom constantly in peak state.Therefore, according to the load of cell
The transmission power of the dynamic adjustment base station of variation just seems necessary.According to Shannon capacity formula, transmission rate with can distribute
Bandwidth or sub-carrier number it is linear, with send power at logarithmic relationship.Therefore, in the premise for keeping QoS of customer
Under, the relationship between adjustable frequency spectrum and transmission power, to achieve the purpose that power is saved.
Summary of the invention
It is calculated to solve the above problems, being distributed the present invention provides a kind of double-layer lap of minimum power for OFDM subcarrier
Method, the algorithm is under conditions of meeting the request of user's minimum-rate, with lower complexity the OFDM subcarrier in system point
Provisioned user can make the power consumption of base station minimum.
The technical solution of the present invention is as follows: the algorithm includes inside and outside two layers of iteration.In interior stacking generation, when two neighboring users
Number of sub carrier wave it is fixed when, internal layer iteration function localbest is used to find the subcarrier of the local optimum of the two users
Apportioning cost.Each user is arranged from left to right, internal layer iterative algorithm moves right a user every time, until it is mobile to the end
One user.Therefore, each external iteration includes (K-1) secondary internal layer iteration.After progress (K-1) secondary internal layer iteration, outside this
Layer is iterating through to be compared with last time external iteration result, judges whether to terminate iterative process.The algorithm specific steps are such as
Under:
(1) parameter initialization, the parameter include the minimum of number of users K, subcarrier number L, subcarrier bandwidth W, user
Rate request rk, base station to each user interchannel noise ratio Gk, iteration ends threshold value ε;
(2) iteration initialization, the subcarrier distribution of K user of random initializtion, and calculate the total power of K user and disappear
Consumption;
(3) in double-layer lap generation: including inside and outside two layers of iteration, each external iteration includes (K-1) secondary internal layer iteration;
(4) the total power consumption of this external iteration system after (K-1) secondary internal layer iteration is calculated;
(5) iteration convergence differentiates: calculating power consumption of the power consumption with respect to last time external iteration of this external iteration
Saving value stops iteration, the subcarrier of this external iteration is assigned as optimal if power saving value is less than decision threshold value
Subcarrier distribution;Otherwise, repeat external iteration process next time.
Further, minimum-rate described in step (1) is requested, and is user under the premise of meeting QoS of customer
The minimum transmission rate needed.
Further, the subcarrier distribution of K user of random initializtion described in step (2), is L subcarrier point
K user of dispensing, and meet the minimum-rate request of user.
Further, K user described in step (2), needs to be ranked up K user and mark the suitable of user
Sequence.
Further, in the step (3), internal layer iterative process is as follows when the t times external iteration:
For m=1:K-1
end
It enables
Further, m secondary internal layer iteration in the step (3) is guaranteeing last iteration two neighboring users m and m+1
The sum of subcarrier it is constant in the case where, the sub-carrier number of two users is redistributed, the power of the two users is made
The sum of consumption minimizes, and the subcarrier of m-th of user of record is the sub-carrier number of this secondary internal layer iteration, the son of the m+1 user
Carrier wave allocation result participates in next secondary internal layer iteration.
Further, (K-2) secondary internal layer iteration, the son of previous user are iterated to from the first secondary internal layer in step (3)
Carrier number is the updated value after current iteration, and the sub-carrier number of the latter user participates in the operation of inner iterative next time, the
(K-1) secondary iteration is updated the sub-carrier number of most latter two user.
Further, step (5) carries out this external iteration after progress (K-1) secondary internal layer iteration.
Further, the iteration convergence in step (6) differentiates, if power saving value is less than decision threshold value, stops changing
Generation, external iteration number are uncertain.
Beneficial effects of the present invention: the present invention can pass through double-layer lap under conditions of meeting the request of user's minimum-rate
OFDM subcarrier in system is distributed to user by generation, to keep the transmission power of base station minimum.In addition, this algorithm is with lower
Complexity.
Detailed description of the invention
Fig. 1 shows total power consumptions under three kinds of different sub-carrier initialization conditions with the situation of change of the number of iterations.
Fig. 2 indicates the total power consumption in base station when the bi-level iterative algorithm proposed and poor search algorithm and average mark sub-carriers
Comparison.
Specific embodiment
In order to better understand the technical content of the present invention, special to lift specific embodiment and institute's accompanying drawings is cooperated to be described as follows.This reality
The major function for applying example is to provide a kind of double-layer lap of minimum power for OFDM Subcarrier Allocation Algorithm, which is meeting
Under conditions of the request of user's minimum-rate, system subcarrier is allocated with lower complexity, makes the power consumption of system
It is minimum.
If radius of society is 500 meters, user is uniformly distributed in cell coverage area, it is assumed that the minimum data rate of user
Request is all identical, is 1kbps.Each subcarrier bandwidth is 1kHz.Assuming that noise power is -115dBm.Assuming that in each time slot
Three users are scheduled.This algorithm can be applied to the situation of more multi-subcarrier and more users.The access of the present embodiment
Method specifically includes the following steps:
Step 1: parameter initialization, including the interchannel noise ratio G of number of users K, sub-carrier number L, user kkAnd minimum-rate
Request rk, subcarrier bandwidth W, iteration ends threshold value ε;
Step 2: iteration initialization, the subcarrier distribution of initialising subscriber calculates total power consumption
P0.It enables
Step 3: internal layer iterative process when the t times external iteration
For m=1:K-1
end
It enables
Calculate total power consumption after the t times iteration
M secondary internal layer iteration is guaranteeing the constant situation of the sum of the subcarrier of last iteration two neighboring users m and m+1
Under, the sub-carrier number of two users is redistributed, the sum of power consumption of the two users is minimized, records m
The subcarrier of a user is the sub-carrier number of this secondary internal layer iteration, and the sub-carrier allocation results of the m+1 user participate in next
Secondary internal layer iteration.
(K-2) secondary internal layer iteration is iterated to from the first secondary internal layer, the sub-carrier number of previous user is after current iteration
Updated value, the sub-carrier number of the latter user participates in the operation of inner iterative next time, and (K-1) secondary iteration is to last two
The sub-carrier number of a user is updated.
Step 4: iteration convergence differentiates.If Pt-Pt-1< ε stops iteration, exports optimal sub-carrier allocation resultsOtherwise, t=t+1 is enabled, next iteration process is repeated.If power saving value is less than
Decision threshold value stops iteration, and external iteration number is uncertain.
Fig. 1 shows total power consumptions under three kinds of different sub-carrier initialization conditions with the situation of change of the number of iterations.Three kinds
Subcarrier initialization is respectively (6,6,6), (1,2,15) and (15,1,2), and the distance of three users to base stations of scheduling is respectively
300 meters, 400 meters and 500 meters, total number of sub carrier wave is 18, the subcarrier being optimal under three sub-carriers initialization scene
The external iteration number that distribution needs is respectively 3,3,4.Fig. 2 indicates that the distance of three users to base stations of scheduling is respectively 100
When rice, 150 meters and 500 meters, the total power consumption of system under the bi-level iterative algorithm of proposition, poor search algorithm, mean allocation algorithm
The case where changing with number of sub carrier wave, it can be seen that the bi-level iterative algorithm of proposition reaches the performance of poor search algorithm, and better than flat
Respectively sub-carriers algorithm.
In the present embodiment, beneficial effect major embodiment of the double-layer lap of minimum power for OFDM Subcarrier Allocation Algorithm
Two aspects: first, algorithm proposed by the present invention only needs the inside and outside level iteration of fewer number, and computation complexity is lower;The
Two, the algorithm proposed using the invention can make the transmission power of base station minimum, reach the performance of poor search algorithm, and than flat
Respectively the performance of sub-carriers algorithm will be got well.
Although the present invention has been disclosed as a preferred embodiment, however, it is not to limit the invention.Skill belonging to the present invention
Has usually intellectual in art field, without departing from the spirit and scope of the present invention, when can be used for a variety of modifications and variations.Cause
This, the scope of protection of the present invention is defined by those of the claims.