CN102223342B - Downlink multi-input single-output-OFDMA (Orthogonal Frequency Division Multiplex Access) multicast system resource allocation method - Google Patents

Downlink multi-input single-output-OFDMA (Orthogonal Frequency Division Multiplex Access) multicast system resource allocation method Download PDF

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CN102223342B
CN102223342B CN201110173715.3A CN201110173715A CN102223342B CN 102223342 B CN102223342 B CN 102223342B CN 201110173715 A CN201110173715 A CN 201110173715A CN 102223342 B CN102223342 B CN 102223342B
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user
group
subcarrier
candidate set
wave beam
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CN102223342A (en
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季飞
邓校成
江兴祥
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South China University of Technology SCUT
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Abstract

The invention relates to a downlink multi-input single-output-OFDMA (Orthogonal Frequency Division Multiplex Access) multicast system resource allocation method which comprises the following steps that in an OFDMA multicast system, a plurality of antennas are arranged at base station equipment, a single antenna is arranged at user terminal equipment, a base station allocates subcarriers for user groups according to channel conditions of the user groups, simultaneously determines transmitting terminal precodings corresponding to the subcarriers for different user groups; through power water injection, power is allocated for the subcarriers allocated to the user groups; the subcarriers and the power allocation are subject to reasonable adjustment to meet the user groups which are not met in data rate requirements. By adopting the method disclosed by the invention, the higher data rate and higher user fairness can be realized, and simultaneously, the lower complexity of the downlink multi-input single-output-OFDMA multicast system resource allocation can be maintained.

Description

One is descending to be entered singly to go out-OFDM multicast system resource allocation methods more
Technical field
The present invention relates to have many transmitting antennas in base station and user only has the resource of the descending multicast system of a transmitting antenna to distribute, particularly a kind of descendingly enters singly to go out-OFDM multicast system resource allocation methods more.
Background technology
Multiple Input Multiple Output (hereinafter to be referred as MIMO technology) can significantly improve by spatial reuse the power system capacity of wireless system.In mimo system, to each channel there is the parallel channel take mutually orthogonal spatial signature vectors (SSV) as feature in mutual independently user, can transmission simultaneously in the situation that not having cochannel to disturb (CCI) through the data of spatial signature vectors precoding.If the space vector of different user is mutually orthogonal, the user data of transmission can be multiplexed in spatial domain simultaneously.In order to improve the link performance of mimo system, need to utilize the knowledge of mimo channel and carry out precoding at transmitting terminal.As a kind of special circumstances of MIMO, in MISO system, receiving terminal only has a reception antenna, so can only carry out precoding at transmitting terminal.
Orthogonal frequency division multiplexi (OFDM) is a kind of multi-carrier communication mode, main thought is by broad-band channel being divided into the subchannel (subcarrier) of a lot of bandwidth much smaller than the correlated bandwidth of channel, and high-speed data-flow is divided into the data flow of multiple low speed and is modulated to respectively in independent subcarrier.Channel distribution reduces selectivity of channel frequency decline, and data flow is divided the intersymbol interval that has increased data flow in each carrier wave, has reduced intersymbol interference.
Enter singly (MISO) system also can dispatch user on spatial domain by the many antennas on base station more; OFDM (OFDMA) system allows, on time-frequency domain, user is carried out to data dispatch.When reusing OFDM OFDMA running time-frequency resource on spatial domain, mean and on same time-frequency, transmit multiple data flow.For the cochannel of eliminating different pieces of information on same time-frequency completely disturbs, the space vector of different user must be mutually orthogonal.Therefore, OFDMA provides the time frequency grid of orthogonal channel between different user, and in spatial domain, MIMO technology Further Division available channel produces mutually orthogonal channel.
In wireless multicast system, user is divided into multiple user's groups, and the use of each user's group receives identical data per family.Only have unique user when every group, system is converted into unicast system; And but in system, only have a group or all use to belong to per family same user's group, system is converted into broadcast system.The same with unicast system, in multicast system, must there is the mechanism of distinguishing different pieces of information; Similar with broadcast system, multicast system must guarantee that all users of every group can reach the desired data rate of this group.Therefore, the resource allocation methods of existing clean culture and broadcast system all can not be applied in multicast system.
Summary of the invention
For overcoming the deficiency of existing correlation technique, main purpose of the present invention is to provide a kind of and descending enters singly to go out-OFDM multicast system resource allocation methods more, to enter singly (MISO) multicast system in descending OFDM (OFDMA) more, it is a kind of resource allocation methods in frequency domain and spatial domain in descending MISO-OFDMA multicast system, the method can realize higher data rate and higher user fairness, reduces descendingly to enter singly to go out-complexity that OFDM multicast system resource is distributed more simultaneously.
Object of the present invention is achieved by following technical proposals:
1), the power of preset all subcarriers estimates initial value, putting subcarrier, just to distribute iterations be 1, is limited to 4 in iteration, starts first run subcarrier and just distribute iteration;
Described power estimates that the preset formula of initial value is:
If sub-carrier number is , each subcarrier on average by
Figure 234926DEST_PATH_IMAGE002
individual user organizes shared, and system gross power is , preset power estimates that initial value is
Figure 382190DEST_PATH_IMAGE004
,
Figure 142336DEST_PATH_IMAGE005
;
2), each user's group has its data rate requirement in system, all users' composition users organize candidate collection;
3), the current subcarrier that is not assigned with for any one, in system, each user of each user's group has corresponding channel fading coefficient, the group channel fading coefficient using channel fading coefficient minimum in each user's group as this user's group; User is organized to the group channel fading coefficient of each user's group in candidate collection and do descending; Group channel fading coefficient take user's group as unit after division descending is to form more than one wave beam candidate set;
4), from the wave beam candidate set producing, select a wave beam candidate set that comprises minimum inactive users; Described inactive users be come from different user groups but there is the different user of the channel matrix of linear correlation, if wave beam candidate set only comprises a group, there is no inactive users;
5) if the wave beam candidate set of selecting only comprises user's group, this user organizes the current subcarrier that acquisition is not assigned with; Then start transmitting terminal precoding algorithm, ask for the transmitting terminal precoding of the unique user's group that has obtained current subcarrier;
6) if the velocity of wave candidate set of selecting comprises multiple user's groups, user's group that this wave beam candidate set comprises all obtains current subcarrier, then make BD and decompose having obtained the channel matrix of each user in each user's group of current subcarrier, organize corresponding transmitting terminal precoding to ask for these users;
7), for the user's group that has obtained current subcarrier, with revise shannon formula calculate the data rate that this subcarrier provides; The data rate that cumulative current all subcarriers of having distributed to this user's group provide, obtains the current data speed that this user organizes; Judge that whether current data speed meets the data rate requirement of this user's group, if meet, organizes this user's group candidate collection and removes name from the rolls from user; If do not meet, this user's group is still retained in user and organizes in candidate collection; Repeating step 3) to step 7), until all subcarriers are all distributed in system, then perform step 8);
8), statistical system subcarrier distribution condition, calculate thus sub-carrier power estimate final value; Judge current subcarrier just distributes iterations whether to equal its upper limit; If equal, perform step 9); Otherwise, all sub-carrier power estimate that initial value is updated to the average of former sub-carrier power estimation initial value and sub-carrier power estimation final value, and make subcarrier just distribute iterations to increase 1, then return to execution step 2), estimate that by new sub-carrier power initial value carries out at the beginning of next wheel carries distributing iteration;
Described sub-carrier power estimates that the calculating formula of final value is:
The system gross power of setting up departments is
Figure 409369DEST_PATH_IMAGE003
, in system, user organizes number and is
Figure 483635DEST_PATH_IMAGE006
, the the sub-carrier number that individual user organizes acquisition is
Figure 83561DEST_PATH_IMAGE008
, the subcarrier allotment of system after multiplexing is
Figure 778503DEST_PATH_IMAGE009
, sub-carrier power estimates that final value is ;
Like this, step 2) form complete one to step 8) and take turns iteration, so, after 4 iteration, subcarrier just distributes iterations will finally arrive the upper limit, now no longer carries out subcarrier and just distributes iteration and turn to step 9);
9), base station total emission power is assigned on the subcarrier of each user's group with water-filling algorithm; According to power division situation, calculate the actual data rate of each user's group, and check whether actual data rate meets the data rate requirement of each user's group; If all meet, resource allocation process finishes; Otherwise, execution step 10);
10), resource is distributed adjustment: check data rate requires the user's group being met whether to have the subcarrier of monopolizing; If user's group has the subcarrier of monopolizing, and the data rate of removing this user's group after this subcarrier requires to be still met, and extracts this subcarrier; So all data rates of traversal require each user's group being met, and the subcarrier extracting is re-assigned to data rate and requires the user's group not being met, and heavily distribute to complete subcarrier; Then re-start power water filling, system resource allocation finishes.
The invention provides a kind of method that forms more than one wave beam candidate set described in step 3), concrete steps are:
, definition a wave beam candidate set, will organize channel fading coefficient and do descending, and the user's group ranking first in descending will be added to this wave beam candidate set, then this user's group is removed name from the rolls from descending; Now, if the number of users that this wave beam candidate set comprises is greater than number of transmit antennas, the current unique user who comprises of this wave beam candidate set organizes and has formed this wave beam candidate set, step 3) leave it at that, and only formed a wave beam candidate set; If the customer volume of this wave beam candidate set is less than or equal to number of transmit antennas, carry out
Figure 219477DEST_PATH_IMAGE012
and step
Figure 461103DEST_PATH_IMAGE013
;
Figure 1805DEST_PATH_IMAGE012
, wave beam candidate set customer volume while being less than or equal to number of transmit antennas, from the residue descending after user's group is removed name from the rolls, find user's group, make the customer volume that adds this user to organize rear wave beam candidate set still be less than or equal to number of transmit antennas; If find, this user's group is also added in wave beam candidate set, then this user's group is removed name from the rolls from residue descending; If can not find, the current user who comprises of wave beam candidate set organizes and has formed this wave beam candidate set, then defines a new wave beam candidate set;
Figure 317380DEST_PATH_IMAGE013
, repeating step
Figure 855809DEST_PATH_IMAGE012
until the descending of group channel coefficients is empty, produce thus more than one wave beam candidate set.
The invention provides the transmitting terminal precoding algorithm described in a kind of step 5), be specially:
If user's group has
Figure 256834DEST_PATH_IMAGE014
individual user
Figure 601228DEST_PATH_IMAGE015
, each user is corresponding to channel matrix and the channel fading coefficient difference of current subcarrier
Figure 768380DEST_PATH_IMAGE016
with
Figure 540027DEST_PATH_IMAGE017
(
Figure 428348DEST_PATH_IMAGE018
), wherein
Figure 310853DEST_PATH_IMAGE019
for dimension matrix, and ,
Figure 919186DEST_PATH_IMAGE022
for matrix norm computing; If the optimum precoding of transmitting terminal is
Figure 543066DEST_PATH_IMAGE023
(
Figure 750056DEST_PATH_IMAGE024
), for other arbitrary transmitting terminal precodings
Figure 801189DEST_PATH_IMAGE025
(
Figure 726420DEST_PATH_IMAGE026
) and arbitrarily
Figure 888411DEST_PATH_IMAGE018
all meet:
Figure 215487DEST_PATH_IMAGE027
Wherein,
Figure 171941DEST_PATH_IMAGE028
for the computing of Matrix Conjugate transposition,
Figure 584468DEST_PATH_IMAGE029
in scope inside get expression formula minimum operation; Random several transmitting terminal precodings of generation
Figure 746381DEST_PATH_IMAGE025
, therefrom find out the transmitting terminal precoding that can meet above formula
Figure 139316DEST_PATH_IMAGE023
, be the transmitting terminal precoding of this user's group corresponding to current subcarrier.
Described in step 10), the sub-carrier power of subcarrier in heavily distributing estimates that initial value value is that last is taken turns subcarrier and just distributes the sub-carrier power of iteration gained to estimate initial value; In heavy assigning process, subcarrier is directly distributed to user's group that first wave beam candidate set comprises, and does not reexamine the inactive users of wave beam candidate set.
Compared with prior art, the present invention has the following advantages:
(1) the present invention, take the subscriber channel coefficient of different user groups corresponding to subcarrier and the inactive users amount that do not comprise on the same group as according to the distribution of determining this subcarrier, has well utilized the multi-user diversity of system;
(2) the present invention estimates initial value by adjusting sub-carrier power, make power estimate and user organize rate estimates preferably realistic sub-carrier power distribute and user organizes speed;
(3) the present invention is by determining corresponding not transmitting terminal precoding on the same group, and the cochannel of having eliminated between the multiple data flow on same subcarrier disturbs, and has reduced computation complexity simultaneously;
(4) data rate that has guaranteed each user's group that heavily distributes of resource of the present invention requires to be met, thereby has obtained the fairness between user's group.
Accompanying drawing explanation
To be that the present invention is descending enter singly to go out Fig. 1 more-machine that the transmits and receives structure of OFDM multicast system;
To be that the present invention is descending enter singly to go out Fig. 2 more-the wireless resource allocation methods flow chart of OFDM multicast system;
Fig. 3 is the algorithm flow chart that subcarrier of the present invention just distributes;
Fig. 4 is the algorithm flow chart of resource re-allocation of the present invention.
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is described further, but be not limited to this.
One of embodiment of the present invention is that the resource of the down link MISO-OFDMA multicast system from base station to user is distributed.
On certain subcarrier of MISO-OFDMA multicast system, the sending/receiving type in certain moment is as follows:
Figure 773560DEST_PATH_IMAGE030
formula (1)
Figure 277354DEST_PATH_IMAGE031
Wherein for user in user's group
Figure 142859DEST_PATH_IMAGE033
the reception signal in a certain moment,
Figure 264398DEST_PATH_IMAGE034
for this user is corresponding to the channel fading coefficient of this subcarrier,
Figure 571883DEST_PATH_IMAGE035
( ,
Figure 462796DEST_PATH_IMAGE035
for
Figure 71631DEST_PATH_IMAGE037
dimension matrix,
Figure 917228DEST_PATH_IMAGE038
for number of transmit antennas) be user
Figure 927909DEST_PATH_IMAGE033
channel matrix,
Figure 833548DEST_PATH_IMAGE039
for user's group
Figure 929680DEST_PATH_IMAGE040
power division on subcarrier,
Figure 576038DEST_PATH_IMAGE041
for user's group
Figure 441225DEST_PATH_IMAGE040
corresponding transmitting terminal precoding,
Figure 517766DEST_PATH_IMAGE042
( ) for sending to user's group
Figure 554172DEST_PATH_IMAGE040
all users' information,
Figure 211549DEST_PATH_IMAGE044
for user
Figure 521308DEST_PATH_IMAGE033
the white Gaussian noise receiving.
Base station receives the channel information of each user group, organizes allocation of subcarriers according to the channel conditions of user and relative users group thereof for user, and definite each group of corresponding transmitting terminal precoding.
For the subcarrier of being monopolized by unique user group, by produce a series of random vectors and find out in the middle of the superior's method obtain transmitting terminal precoding, detailed process is as follows:
If this user's group has
Figure 529715DEST_PATH_IMAGE014
individual user
Figure 583122DEST_PATH_IMAGE045
, the channel matrix of corresponding subcarrier is respectively
Figure 360585DEST_PATH_IMAGE046
, wherein
Figure 841245DEST_PATH_IMAGE047
(
Figure 336948DEST_PATH_IMAGE018
) be
Figure 928467DEST_PATH_IMAGE048
dimension matrix (channel vector), and
Figure 560436DEST_PATH_IMAGE049
, for matrix norm computing; Corresponding channel fading coefficient is .If the optimum precoding of transmitting terminal is
Figure 593136DEST_PATH_IMAGE023
(
Figure 345191DEST_PATH_IMAGE048
dimension matrix), for other arbitrary transmitting terminal precodings
Figure 167654DEST_PATH_IMAGE025
(
Figure 372370DEST_PATH_IMAGE026
) and arbitrarily
Figure 571270DEST_PATH_IMAGE018
all meet:
Figure 177832DEST_PATH_IMAGE052
formula (2)
Wherein,
Figure 171196DEST_PATH_IMAGE053
for the computing of Matrix Conjugate transposition,
Figure 863209DEST_PATH_IMAGE054
for getting the minimum operation in prescribed limit.
Organize shared subcarrier for multiple users, for the cochannel of eliminating on same subcarrier disturbs, need that the channel matrix of multiple user's groups is made to BD and decompose, to obtain transmitting terminal precoding.
BD decomposes reference literature (Quentin H. Spencer, A. Lee Swindlehurst, and Martin Haardt, Zero-forcing methods for downlink spatial multiplexing in multiuser MIMO channels, IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 52, NO. 2, FEBRUARY 2004.
Lai-U Choi and Ross D. Murch, A Transmit Preprocessing Technique for Multiuser MIMO Systems Using a Decomposition Approach, IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 3, NO. 1, JANUARY 2004.), concrete decomposable process is as follows:
Be provided with
Figure 600220DEST_PATH_IMAGE006
individual user's group (is respectively user's group
Figure 61289DEST_PATH_IMAGE055
) share same subcarrier, the number of users of each user's group is respectively , have .If the
Figure 883248DEST_PATH_IMAGE058
group the individual user's channel matrix is respectively
Figure 796639DEST_PATH_IMAGE060
( ), this
Figure 542058DEST_PATH_IMAGE006
the channel matrix that individual user organizes all users forms matrix, for:
Figure 40036DEST_PATH_IMAGE062
?（
Figure 749366DEST_PATH_IMAGE063
）
In order to obtain individual user organizes corresponding transmitting terminal precoding, from matrix
Figure 520193DEST_PATH_IMAGE064
middle extraction
Figure 810360DEST_PATH_IMAGE058
organize after channel vector corresponding to each user, then the channel vector of all the other user's groups is formed to new matrix, then carry out matrix transpose, obtain formula (3)
Wherein
Figure 128526DEST_PATH_IMAGE066
for matrix transpose computing, right
Figure 549143DEST_PATH_IMAGE067
make SVD and decompose:
Figure 959395DEST_PATH_IMAGE068
formula (4)
Obtain
Figure 72845DEST_PATH_IMAGE069
organize corresponding transmitting terminal precoding
Figure 935759DEST_PATH_IMAGE070
, in like manner can arrive its user and organize corresponding transmitting terminal precoding.
For the user's group that has obtained subcarrier, with revise shannon formula calculate the data rate that this subcarrier provides; The data rate that cumulative current all subcarriers of having distributed to this user's group provide, obtains the current data speed that this user organizes.For system (the reference literature Goldsmith A J of M-QAM modulation system, Chua S. Variable-rate variable-power MQAM for fading channels. IEEE Transactions on Communications.1997.45 (10): 1218-1230), calculate user's group by following formula
Figure 160067DEST_PATH_IMAGE040
present rate:
Figure 150458DEST_PATH_IMAGE071
formula (5)
Figure 434808DEST_PATH_IMAGE072
Wherein
Figure 785018DEST_PATH_IMAGE073
,
Figure 813017DEST_PATH_IMAGE074
be respectively and obtain the forward and backward data rate of subcarrier,
Figure 932283DEST_PATH_IMAGE075
for the power of subcarrier is estimated initial value,
Figure 121956DEST_PATH_IMAGE076
for the bandwidth of subcarrier,
Figure 959462DEST_PATH_IMAGE077
,
Figure 525572DEST_PATH_IMAGE078
be respectively
Figure 764924DEST_PATH_IMAGE040
the poorest user's of group channel conditions channel coefficients (
Figure 125498DEST_PATH_IMAGE040
the group channel coefficients of group) and channel matrix,
Figure 450300DEST_PATH_IMAGE079
for the transmitting terminal precoding to organizing,
Figure 820101DEST_PATH_IMAGE080
the variance of white Gaussian noise,
Figure 648380DEST_PATH_IMAGE081
for error rate requirement.
As shown in Figure 2, after the grouping information and channel information of base station by all users in dedicated channel acquisition system, this resource allocation algorithm is from following steps for step of the present invention:
Step 1: carry out subcarrier and just distribute iteration, and determine the transmitting terminal precoding of each group of corresponding different sub carrier;
Step 2: be the each group of corresponding subcarrier distribution power distributing by power water filling;
Step 3: the data rate that judges whether all user's groups requires to be all met, and if so, algorithm finishes, otherwise, execution step 4;
Step 4: implement resource re-allocation, algorithm finishes.
Subcarrier described in step 1 just distributes iterative process figure as shown in Figure 3:
(1): initialization first round subcarrier just distributes iteration: preset sub-carrier power is estimated initial value; It is 1 that initialization subcarrier just distributes iterations, and sets on it and be limited to 4.The system sub-carrier number of setting up departments is
Figure 445435DEST_PATH_IMAGE001
, average each subcarrier by
Figure 991954DEST_PATH_IMAGE002
individual group share ( ,
Figure 110881DEST_PATH_IMAGE002
can value 2), system gross power is , can preset sub-carrier power estimate that initial value is
Figure 174969DEST_PATH_IMAGE004
.
Figure 824256DEST_PATH_IMAGE002
size only affect sub-carrier power and estimate the convergence rate of initial value, do not affect its convergence;
(2): all users of system organize formation user and organize candidate collection, and first subcarrier of pointing system;
(3): user is organized to each the user's group in candidate collection, selects the user of the channel fading coefficient minimum that current subcarrier is corresponding, and with its channel coefficients the group channel coefficients as this group; Group channel coefficients will be used for calculating the current data speed of user's group in subsequent step;
(4): each user's group of arranging user and organize candidate collection by the descending of group channel fading coefficient;
(5): divide above-mentioned arrangement to form more than one wave beam candidate set, partition process is as follows:
Figure 689444DEST_PATH_IMAGE011
organize the subscriber channel coefficient of interior minimum using user as the group channel coefficients of this user's group; Arrange user's group by the descending of group channel coefficients;
Figure 765984DEST_PATH_IMAGE012
define a wave beam candidate set, and the user's group ranking first in descending is added to wave beam candidate set, then this user's group is removed name from the rolls from arrange; Now, if the customer volume of wave beam candidate set is greater than number of transmit antennas
Figure 349413DEST_PATH_IMAGE038
, the current unique user who comprises of wave beam candidate set organizes and has formed this wave beam candidate set, and step (5) leaves it at that; Otherwise, carry out
Figure 536811DEST_PATH_IMAGE013
with
Figure 522085DEST_PATH_IMAGE082
;
Figure 769527DEST_PATH_IMAGE013
the customer volume of wave beam candidate set is less than or equal to
Figure 840251DEST_PATH_IMAGE038
time, in arrangement, find a group, make to add the customer volume of wave beam candidate set after this group to be still less than or equal to
Figure 831341DEST_PATH_IMAGE038
.If find, this group also adds in wave beam candidate set, and this group is removed name from the rolls from arrange; If can not find, the current user who comprises of wave beam candidate set organizes and has formed this wave beam candidate set, then defines a new wave beam candidate set;
Figure 671121DEST_PATH_IMAGE082
repeat
Figure 89464DEST_PATH_IMAGE013
until the descending of group channel coefficients is empty, produce thus multiple wave beam candidate set.
(6): subcarrier distributes: if only formed a wave beam candidate set in step (5), the group that this wave beam candidate set comprises obtains current subcarrier; If formed multiple velocity of wave candidate set in step (5), therefrom select and comprise a minimum wave beam candidate set of inactive users, its each user who comprises organizes and obtains current subcarrier pointed; The calculating of inactive users quantity obtains by calculating not the number of users of channel matrix linear correlation on the same group;
(7): organize for obtaining the user of subcarrier the transmitting terminal precoding of determining corresponding current subcarrier.Here, if subcarrier is monopolized by user's group, ask for according to formula (2); If it is shared that subcarrier has multiple users to organize, ask for according to formula (3), (4);
(8): calculate the current data speed of each group that has obtained current subcarrier according to formula (5);
(9): for each user's group that has obtained current subcarrier, judge that can its present rate meet the rate requirement of this group; If meet, execution step (10); Otherwise execution step (11);
(10): current data speed can meet each user's group of its data rate requirement to be organized candidate collection and remove name from the rolls from user, then perform step (11);
(11): judge current whether last subcarrier of pointing system; If so, execution step (12); Otherwise, execution step (13);
Step (12): last subcarrier of current sensing, epicycle subcarrier is assigned to this and completes, and can obtain the distribution condition of subcarrier and calculate sub-carrier power and estimate final value;
In system, user organizes number and is , the
Figure 176685DEST_PATH_IMAGE007
the sub-carrier number that individual user organizes acquisition is
Figure 870972DEST_PATH_IMAGE008
, the subcarrier allotment of system after multiplexing is
Figure 463146DEST_PATH_IMAGE009
, sub-carrier power estimates that final value is
Figure 508462DEST_PATH_IMAGE010
;
(13): current is not to point to last subcarrier, and the next subcarrier of pointing system, then returns to execution step (3);
(14): judge subcarrier just distributes iterations counting whether to equal its upper limit.If so, step 1 finishes, and subcarrier is just assigned; Otherwise sub-carrier power estimates that initial value is updated to the average of initial value and final value, and make subcarrier just distribute iterations to increase 1, then return to execution step (2);
Fig. 4 has shown the flow process of resource re-allocation algorithm, realizes after the distribution of base station total emission power, organizes and does not reach its rate requirement if be checked through user, carries out resource re-allocation, and detailed process is presented below:
A: take out such subcarrier the user's group that requires to be met from all data rates: this subcarrier meets group by one to be monopolized, and removes after this subcarrier, this data rate that meets group requires to be still met.All subcarriers that meet this condition form heavy allocation of subcarriers set, for not meeting group selection;
B: point to first subcarrier in heavy allocation of subcarriers set;
C: all satisfied groups form heavy assign group Candidate Set;
D: arrange each group in heavy assign group Candidate Set by the descending of group channel coefficients corresponding to the subcarrier of current sensing;
E: form a wave beam candidate set according to arranging, its user who comprises organizes and obtains current subcarrier, and the formation of wave beam candidate set can just distribute referring to subcarrier the step (5) of iterative process;
F: determine that the user who obtains subcarrier organizes corresponding transmitting terminal precoding, method is just distributed the step (7) of iterative process with subcarrier;
G: the current data speed of calculating the each user's group that obtains heavy allocation of subcarriers according to formula (5).In formula (5), user's group at existing data rate is
Figure 903672DEST_PATH_IMAGE073
, and subcarrier last is taken turns the sub-carrier power that iteration obtains and estimates that initial value is in just distributing
Figure 390148DEST_PATH_IMAGE083
;
H: judge whether the estimation rate that does not meet group that obtains subcarrier reaches requirement; If so, perform step i; Otherwise, carry out j;
I: the estimation rate that does not meet group that obtains subcarrier reaches requirement, and this group is removed name from the rolls from group Candidate Set, then performs step j;
J: whether the subcarrier that judges current sensing weighs last in allocation of subcarriers set; If so, perform step l; Otherwise, execution step k;
K: the subcarrier of current sensing is not last in heavy allocation of subcarriers set, points to the next subcarrier in heavy allocation of subcarriers set;
L: the subcarrier of current sensing is last in heavy allocation of subcarriers set, and subcarrier is heavily assigned, by power water filling to complete power division.Arrive this, resource re-allocation completes.

Claims (2)

1. descending enter singly to go out-an OFDM multicast system resource allocation methods more, it is characterized in that, step is as follows:
1), the power of preset all subcarriers estimates initial value, putting subcarrier, just to distribute iterations be 1, is limited to 4 in iteration, starts first run subcarrier and just distribute iteration;
Described power estimates that the preset formula of initial value is:
If sub-carrier number is u, each subcarrier is on average organized shared by f user, and system gross power is Q, and preset power estimates that initial value is P gue=Q/ (f*u), f>=1;
2), each user's group has its data rate requirement in system, all users' composition users organize candidate collection;
3), the current subcarrier that is not assigned with for any one, in system, each user of each user's group has corresponding channel fading coefficient, the group channel fading coefficient using channel fading coefficient minimum in each user's group as this user's group; User is organized to the group channel fading coefficient of each user's group in candidate collection and do descending; Group channel fading coefficient take user's group as unit after division descending is to form more than one wave beam candidate set;
4), from the wave beam candidate set producing, select a wave beam candidate set that comprises minimum inactive users; Described inactive users be come from different user groups but there is the different user of the channel matrix of linear correlation, if wave beam candidate set only comprises a group, there is no inactive users;
5), if the wave beam candidate set of selecting only comprises user's group, this user organizes and obtains this current subcarrier not being assigned with; Then start transmitting terminal precoding algorithm, ask for the transmitting terminal precoding of the unique user's group that has obtained current subcarrier;
6) if the velocity of wave candidate set of selecting comprises multiple user's groups, user's group that this wave beam candidate set comprises all obtains current subcarrier, then make BD and decompose having obtained the channel matrix of each user in each user's group of current subcarrier, organize corresponding transmitting terminal precoding to ask for these users;
7), for the user's group that has obtained current subcarrier, with revise shannon formula calculate the data rate that this subcarrier provides; The data rate that cumulative current all subcarriers of having distributed to this user's group provide, obtains the current data speed that this user organizes; Judge that whether current data speed meets the data rate requirement of this user's group, if meet, organizes this user's group candidate collection and removes name from the rolls from user; If do not meet, this user's group is still retained in user and organizes in candidate collection; Repeating step 3) to step 7), until all subcarriers are all distributed in system, then perform step 8);
8), statistical system subcarrier distribution condition, calculate thus sub-carrier power estimate final value; Judge current subcarrier just distributes iterations whether to equal its upper limit; If equal, perform step 9); Otherwise, all sub-carrier power estimate that initial value is updated to the average of former sub-carrier power estimation initial value and sub-carrier power estimation final value, and make subcarrier just distribute iterations to increase 1, then return to execution step 2), estimate that by new sub-carrier power initial value carries out next round subcarrier and just distributes iteration;
Described sub-carrier power estimates that the calculating formula of final value is:
The system gross power of setting up departments is Q, in system user to organize number be nb, the sub-carrier number that i user organizes acquisition is N i, the subcarrier allotment of system after multiplexing is
Figure FDA0000428391050000021
sub-carrier power estimates that final value is P gus t=Q/l;
9), base station total emission power is assigned on the subcarrier of each user's group with water-filling algorithm; According to power division situation, calculate the actual data rate of each user's group, and check whether actual data rate meets the data rate requirement of each user's group; If all meet, resource allocation process finishes; Otherwise, execution step 10);
10), check data rate requires the user's group being met whether to have the subcarrier of monopolizing; If user's group has the subcarrier of monopolizing, and the data rate of removing this user's group after this subcarrier requires to be still met, and extracts this subcarrier; So all data rates of traversal require each user's group being met, and the subcarrier extracting is re-assigned to data rate and requires the user's group not being met, and heavily distribute to complete subcarrier; Then re-start power water filling, system resource allocation finishes.
2. according to claim 1 descendingly enter singly to go out-OFDM multicast system resource allocation methods more, it is characterized in that, the concrete steps that form more than one wave beam candidate set described in step 3) are:
1., definition a wave beam candidate set, will organize channel fading coefficient and do descending, and the user's group ranking first in descending will be added to this wave beam candidate set, then this user's group is removed name from the rolls from descending; Now, if the number of users that this wave beam candidate set comprises is greater than number of transmit antennas, the current unique user who comprises of this wave beam candidate set organizes and has formed this wave beam candidate set, step 3) leave it at that, and only formed a wave beam candidate set; If the customer volume of this wave beam candidate set is less than or equal to number of transmit antennas, carry out 2. with step 3.;
2., the customer volume of wave beam candidate set is while being less than or equal to number of transmit antennas, finds user's group from the residue descending after user's group is removed name from the rolls, and makes the customer volume that adds this user to organize rear wave beam candidate set still be less than or equal to number of transmit antennas; If find, this user's group is also added in wave beam candidate set, then this user's group is removed name from the rolls from residue descending; If can not find, the current user who comprises of wave beam candidate set organizes and has formed this wave beam candidate set, then defines a new wave beam candidate set;
3., 2. repeating step until the descending of group channel coefficients is empty, produces more than one wave beam candidate set thus.
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