CN1463098A - Resource scheduling method utilized in operations sensitive to downward error in OFDM - Google Patents

Abstract

The invented method includes following steps with characters of supporting hybrid automatic feed back request (HARQ) technique. In preparing step, the dispatching cycle is fixed. Several adjacent sub carrier waves constitute the sub band. The resource composed of several sub bands is dispatched once a time in each time slot. Then, the mobile station feeds back the word of data rate control (DRC) obtained by quantizing average S/N ratio based on each sub band. In the step of dispatching retransmission data, after calling out the parameters of the scheme at last transmission for retransmission data, the retransmission data are fed back for several transmissions, which have largest DRC, in user's all available sub bands. The invention uses the low error rate of HARQ method and gives attention to both of fairness and system efficiency, and processes low feedback quantity and control amount of information.

Description

The resource regulating method that is used for mistake responsive type business under the OFDM

Technical field

The resource regulating method that is used for mistake responsive type business under the OFDM belongs to the scheduling of resource technology of wireless communication field.

Background technology

The growing communication system that requires of wireless data service demand is transmitted various types of data flexibly at high speed, and as the high-speed multimedia business, low speed the Internet is browsed and low speed voice service etc.These business can be divided into time-delay responsive type and mistake responsive type two classes.Time-delay responsive type business is very high to propagation delay time and delay variation requirement, but can tolerate transmission error to a certain degree.And mistake responsive type business is higher to the accuracy requirement of transfer of data, but does not have strict delay requirement, so it also can be called non-real-time service.To this business, the suitable HARQ technology that adopts further improves its error performance.How to dispatch the limited wireless frequency spectrum resource, on the basis of certain fairness, improve system effectiveness, become one of key issue of following wireless communication field.

Wireless communication system is experiencing huge development.Wherein, orthogonal frequency division multiplexi (OFDM) is one of mainstream technology that solves at present high speed data transfer, and band segmentation is become many orthogonal subcarriers, the parallel signal that sends.It has higher spectrum efficiency and opposing multipath interference capability, successfully is used for ordering digital video by short message (DVB), asymmetric user data ring (ADSL) and wireless access network system, has a good application prospect at moving communicating field.

Ofdm system is a multicarrier system.Actual wireless channel is a time-varying system, not only has path loss and shadow fading, and also has multipath and Doppler frequency shift phenomenon.Therefore, not only receive the decline difference of signal in the different mobile stations of synchronization, even and the signal fadeout of travelling carriage on different sub carrier also different.Decline that it should be noted that adjacent sub-carrier has certain correlation.

In order to improve systematic function, ofdm system adopts adaptive coding and modulating (AMC) technology and mixes and feed back (HARQ) technology of re-transmission (Das, A. automatically; Khan, F.; Sampath, A.; Hsuan-Jung Su, " Performance of hybrid ARQ for high speeddownlink packet access in UMTS ", VTC ' 2001.pp2133-2137, vol.4.).AMC changes constellation size, code efficiency and encoding mechanism neatly.It improves the availability of frequency spectrum when channel is good, reduce throughput in the time of bad channel, thereby improved the error rate (BER) performance.HARQ does not then reduce the error rate effectively when the error rate is not very high, and obtains desirable throughput.Real system often adopts the HARQ of Stop And Wait, just makes a start to keep the current data grouping always, is successfully received up to it.This mechanism realizes simple, and the feedback data amount is few.

This patent has proposed the dispatching method of mistake responsive type business under a kind of ofdm system.In order to improve system spectral efficiency and throughput, need basis propagation characteristic at that time, the Radio Transmission Technology according to system adopts adopts rational algorithm, realizes dynamic time frequency two-dimensional resources scheduling between different user.

The scheduling of resource research of traditional OFDM mainly is than bit loading and power division.Than bit loading is that how decision is loaded into data bit on each subband according to the transmission quality of each subcarrier, can be divided into power optimization according to optimisation criteria and (see L.Piazzo:Fast algorithm for power and bit allocation in OFDM systems.ELECTRONICSLETTERS, 9 ^ThDecember 1999, Vol 35, No 25, pp2173～2174. and Lai.S.K, Cheng R.S and Letaief K.B:Adatpive trellis coded MQAM and power optimization for OFDM transmission.Proc.IEEE VTCSpring, Houston, 1999), throughput-maximizedly (see Satoshi MUNETA, " A new frequency-domain linkadaptation scheme for broadband OFDM systems ", ISBN:0-7803-5435-4, VTC ' 99, pp253～257) and minimum bit-error rate (see C.Y.Wong, R.S.Cheng, K.B.Letaief, R.D.Murch, ' Multiuser OFDM withAdaptive Subcarrier, Bit and Power Allocation ', IEEE J.on SAC, vol.17, No.10,1999. and InhyoungKim, H.L. Lee, et al. " On the Use of Linear Programming for Dynamic Subchannel and BitAllocation in Multiuser OFDM ", IEEE Global Telecommunications Conference, v 6,2001, p3648-3652.) three major types type.These are difficult to be applied directly in the real system according to the optimization algorithms obtain of deriving, because their system's computing expense and feedback information volume, control information expense are too big.

The scheduling of resource of wireless network is very high to the requirement of algorithm.Different with cable network, wireless network bandwidth resource anxiety becomes during link capacity and abominable, transmission error rates height not only, and also error burst is strong.Early stage Wireless Scheduling Algorithms is to improve the dispatching algorithm of cable network according to the characteristics of wireless channel, and the focus of research is fairness and system effectiveness.Wherein, most representative algorithm has CSDPS (channel status is packet scheduling channel state dependent packet scheduling independently), IWFQ (idealized wireless fairness queuing algorithm idealized wireless fair queuing), SBFA (Yaxin Cao such as (based on server's fairness algorithm server-based fair approach), Victor O.K.LI, " Scheduling Algorithms inBroad-Band Wireless Networks ", IEEE Proceddings of The IEEE, VOL.89, NO.1,2001.).

Above-mentioned algorithm is based upon on the channel model of two condition Markov process, and wireless channel has only and can transmit and can not transmit two states.But the capacity of actual wireless channel is multiple possibility value.By the many-valued two-value that is simplified to, must bring the efficiency of transmission loss to channel capacity.

At this problem, HDR (high data rate high data rate) system adopts the dynamic data rate technology.It utilize the AMC technology realize transmission capacity by binary states to polymorphic expansion, thereby realized transmitting efficiently.It has at first introduced the DRC/R algorithm, approach most the user (C.Rentel of transmittability peak value in a period of time for current Channel Transmission ability resource allocation, W.Krzymien, B.Darian, " Comparative forward link traffic channel performance evaluation of HDR andXTREME systems ", in VTC2002).It realizes proportional fairness criterion with simple method, has realized good compromise between fairness and throughput of system.

The HDR system is by the resource-sharing between the realization of the scheduling of resource on time domain user.The user who obtains scheduling will monopolize all system resources before the scheduling next time.For the fairness between the user, the user that transmittability is lower obtains will keep the long time after the power of dispatching, and then dispatches next time.

HDR is a single-carrier system, so it does not need frequency resource is dispatched.If the dispatching algorithm among the HDR is applied directly on the ofdm system of multicarrier and can reduces system effectiveness.Because do not carry out the different transmittabilities that the Domain Dynamic scheduling just can not embody each subcarrier on the ofdm system, also just can't obtain the user diversity gain on the frequency.

Except the HDR system, blue tooth agreement, the development of wireless ATM and WLAN wireless networks such as (WLAN (wireless local area network)) has also caused the research of the scheduling of resource of system separately.But the Radio Transmission Technology that these systems adopt and the difference of native system are bigger, so their scheduling scheme is little to the reference function of native system.

The mistake responsive type business that this patent is mainly studied each travelling carriage is access in control and admits (CAC) afterwards, and scheduling of resource is carried out for these business in the base station how.Dynamic Resource Allocation for Multimedia (DRA) module has been set up in the base station, engraves each frequency configure user data during for each of ofdm system, and determines every kind of each data quantity transmitted of business and code modulation mode.It supports HARQ mechanism, is reasonably compromised between fairness and throughput of system.

Summary of the invention

The purpose of this invention is to provide a kind of dispatching algorithm of under the OFDM transmission means, supporting the mistake responsive type business of HARQ technology, between throughput of system and fairness, obtain good compromise.

It is that a kind of OFDM of being used for supports down to mix the resource regulating method that feedback automatically retransmits the mistake sensitiveness business of (HARQ) technology, and it distributes corresponding frequency domain sub band resources by following three phases so that taking into account under the principle that reduces the error rate and optimized throughput to each non-real-time service successively:

(1) preparatory stage:

In the fixed schedule cycle, carry out once scheduling at a time slot; It is divided into a subband to plurality of sub carrier wave adjacent in the ofdm system, adopts the identical power division mode of average transmitting power of identical code modulation mode and each subband; As the minimum unit of first resource scheduling, each subband is once only being distributed to a user in the scheduling;

System adopts the closed loop feedback method; Each travelling carriage MT measures the average signal-to-noise ratio SNR of each subband in a time slot, and quantizes the data rate control word DRC that signal to noise ratio obtains correspondence by certain threshold schemes, again according to the time interval of traffic carrying capacity needs decision feedback and the quantity of feedback;

(2) stage of the data of scheduling re-transmission

Scheduling sequence between the user to be retransmitted is at random.Corresponding each user data to be retransmitted, scheduling are chosen and original identical subband number and coded modulation scheme, divide the highest some subbands of DRC of this MT feedback to the user;

(3) stage of the non-re-transmission user data of scheduling

On each subband of not dispatching, estimate its priority assessment value, each allocation of subbands is given the user of corresponding assessed value maximum; Application has the good throughput of system and the proportional fairness criterion of user fairness on each subband, and the priority assessment value that subband j goes up user i is: $\mathrm{Prio}\_{\mathrm{eval}}_{i,j}=\frac{{\mathrm{Capa}}_{i,j}}{R_i},i=\mathrm{1,2},...,N;j=\mathrm{1,2},...,M--\left(1\right)$

Wherein, Capa _{I, j}It is the transmission capacity in the time slot obtaining of the suggestion feedback velocity DRC according to i user's j subband;

R _iBe the average transmission rate of user i in a period of time, can be represented by the formula:

R _i＝(1-1/T _c)·R _i+Len _i/T _c，i＝1，2，...，N??????????????????????????????(2)

T _cBe the adjustable parameter of proportional fairness algorithm the inside, reacted maximum endurable time delay;

Len _iBe to distribute to total transmission capacity that the DRC by travelling carriage feedback of all subband correspondences of i assessed value business tables look-up and obtains in this time slot, can be represented by the formula: ${\mathrm{Len}}_i=\underset{j}{\overset{M}{\mathrm{\Σ}}}{\mathrm{Capa}}_{i,j}\·\mathrm{Slelect}\_{\mathrm{all}}_{i,j},i=\mathrm{1,2},...,N---\left(3\right)$ When j subband distributed to i user's assessed value business, Select_all _{I, j}=1, otherwise be zero; The data aggregate coded modulation of same user on different sub-band adopts the highest modulation system of advising; In the described scheduling preparatory stage, for the HARQ scheme that adopts Stop And Wait, travelling carriage will feed back to induction signal (ACK) and version information; The ACK that retransmits feedback is 0 data.

Described dispatching method contains following steps successively:

(1) information gathering is for formation adds new data and built-in variable initialization;

(2) scheduling data to be retransmitted:

(2.1) determine the user's that remains to be retransmitted number N;

(2.2) the DRC message scheduling data retransmission of the user's that retransmits according to the needs collected of base station travelling carriage feedback:

(2.2.1) for each user to be retransmitted, all available subbands according to DRC rank order from big to small;

(2.2.2) take out this batch data transmission plan of last time from memory cell;

(2.2.3) select for this user and last time same number the highest some subbands of available DRC;

(3) scheduling of non-re-transmission user data:

(3.1) determine the unappropriated number of sub-bands M ' of non-re-transmission user number N ' Buddhist monk to be passed;

(3.2) give the highest user of priority assessment value on respective sub-bands each allocation of subbands.Effect analysis:

This dispatching algorithm is the application percentage fairness criterion in the scheduling of subband, can improve throughput of system on the basis that ensures certain fairness.By this algorithm under the ofdm system non-real-time service being carried out the emulation of the scheduling performance of best-effort, we find, this algorithm is owing to carry out two-dimentional dynamic resource scheduling in time-frequency two territories, so the throughput of system performance is better than the performance of only carrying out scheduling of resource in time domain, more be better than the pre-allocation of resources algorithm.And its fairness is better, can obtain fairness between the user preferably, and insensitive to the value of parameter Tc.Its compatible HARQ technology, delay performance is relatively poor, but more excellent bit error rate performance is arranged, and is particularly suitable for the scheduling of mistake responsive type business.Because adopted the technology of dividing subband, travelling carriage and base station are inquired about subband signal-noise ratio threshold transmission plan table jointly, feedback quantity and control information amount all descend on a large scale.

Description of drawings

Fig. 1 represents the realization flow of scheduling of resource.

Fig. 2 is expressed as the data structure of supporting HARQ and increasing.

Fig. 3 represents to dispatch the flow process of data retransmission.

Fig. 4 represents to dispatch the flow process of non-data retransmission.

Fig. 5 represents that system sends block diagram.

Embodiment

Fig. 1 has provided the realization flow of this scheduling scheme, and whole flow process is divided into five subprocess.The task of first subprocess is to carry out information gathering and initial work.In this step, each travelling carriage is measured the SNR that descending pilot frequency obtains each subcarrier respectively, is averaged the average SNR that obtains each subband in a period of time again.Then, the signal-noise ratio threshold value of its question blank 1 obtains corresponding DRC.Then, travelling carriage feeds back DRC whole or part high-quality subband and corresponding subband ID thereof according to the downlink business demand of self.For the business that has adopted the HARQ scheme, re-transmission ack signal and version number that travelling carriage is also relevant with feedback.The feedback time interval and the fl transmission mode of these feedback informations, there is concrete analysis the back.

?DRC	Signal to noise ratio (dB)	Code rate	Modulation type	Capacity (bit/time slot)
					??0	????/	????/	????/	??????0
??1	????-3.4	????1/4	????BPSK	??????128
					??2	????-0.4	????1/2	????BPSK	??????256
??3	????2.2	????1/2	????QPSK	??????512
					??4	????5.2	????3/4	????QPSK	??????768
??5	????7.6	????2/3	????8PSK	??????1024
					??6	????10.9	????3/4	????16QAM	??????1536
??7	????14.5	????2/3	????64QAM	??????2048

Table 1 transmission plan

The different user basis is the size and the importance of data to be transferred amount separately, and the variation characteristics of channel are decided the algorithm of suggested data rate in its sole discretion.For exigent user, time that can be short, just calculating was once current passes data volume, and adopts the algorithm of more accurate information theory capacity.On the contrary, very low for data volume, the user that the QOS index is lower, the way that just can adopt more rough average signal-to-noise ratio thresholding to table look-up.

During initialization, the ACK information that receives is analyzed in the base station.If finding has travelling carriage that the re-transmission requirement is arranged, system enters second subprocess so, and scheduling needs the data of re-transmission.We think that the priority of the data that retransmit is higher than other all data, thus the data that retransmit of scheduling at first, and choose and the same subband number and coded modulation scheme originally, the available subband best with this user passes.These storage data waiting for transmission of will seeking survival, and note down each professional each data total length and other transmission information.Increase data structure as shown in Figure 2 for this reason.

Its scheduling process as shown in Figure 3.Each user to be retransmitted the scheduling in, all available subbands according to DRC sequence arrangement from big to small.Take out corresponding data from memory cell, and the transmission plan of this data last time, as subband number and coded modulation scheme, determine current transmission manner.For this user uses the subband identical with last time on a selective basis up to there not being enough resources.

It is professional to dispatch non-re-transmission then.Travel through the subband that all are not dispatched, will distribute to (1) user that value is the highest on relevant subbands to them, idiographic flow as shown in Figure 4.After all subbands all dispense, determine the data and the coded modulation mapping scheme of transmission for each non-re-transmission user.Dual mode is arranged: a kind of is that the different sub-band of a business is all done respectively according to the DRC corresponding codes modulation system of travelling carriage feedback, and its advantage is not need to tell travelling carriage coded modulation information, saves Downlink Control Information.

Another kind of mode be all subbands of distributing of same user as an overall transfer, adopt unified transmission means, its advantage is to obtain the bigger gain that interweaves.Specifically will be exactly transmission capacity sum according to each subband correspondence as last transmission capacity, the modulation scheme of corresponding maximum be a unified modulation scheme at last.Again according to them, instead release final code rate.

After the transmission means of all data was determined, AP strengthened protection to the user ID of all allocation of subbands and corresponding original DRC information afterwards by notifying each MT on the common down channel.Because the accuracy of feedback data directly influences the efficient and the accuracy rate of system, so need to strengthen protection.The coding redundancy protection is adopted in the protection of feedback information, and 1/3 convolution code and lower modulation system are adopted in suggestion, can also increase the transmitting power of corresponding bits in the time of necessary.

Provide the object lesson that a system realizes below.Whole system sends block diagram partly as shown in Figure 5.Suppose in the ofdm system that each symbol has 1024 subcarriers, be divided into 16 subbands, 64 subcarriers of each subband.A time slot is made up of 8 symbols.Choose one after the parameters R initialization and approach 0 positive number, such as 0.001.Parameter T _cSelect 500.

Table one has provided a kind of transmission plan of the subband average signal-to-noise ratio being carried out 8 rank quantization thresholds.In suc scheme, the independent coded modulation of each subband.The subband AMC parameter of suggestion has: do not pass, 1/4Turbo sign indicating number and BPSK, 1/2Turbo sign indicating number and BPSK, 1/2Turbo sign indicating number and QPSK, 3/4Turbo sign indicating number and QPSK, 2/3Turbo sign indicating number and 8PSK, 3/4Turbo sign indicating number and 16QAM, 2/3Turbo sign indicating number and 64QAM, corresponding throughput is 0,1/4,1/2,1,3/2,2,3 respectively, 4bits/s/Hz.

HARQ adopts Stop And Wait, and the upper limit of number of retransmissions is 4.Travelling carriage feeds back the ACK information of 1 bit according to the CRC check result who receives data.If CRC check is a loading error occurring, and the number of times that retransmits is less than 4, ACK=0 then, otherwise ACK=1.Until the travelling carriage feeding back ACK=1 the time, next packet is just transmitted in the base station; Otherwise, if ACK=0 then retransmits.

Each travelling carriage is to the transmission characteristic of AP feedback of down channel.At first, it measures the average SNR of each subcarrier in the time slot by pilot tone, is averaged the average SNR that obtains each subband again.Then, the signal-noise ratio threshold value of its question blank 1 obtains corresponding DRC.If the downlink service data amount of this travelling carriage is very big, so can be all or choose optimum some AP of feeding back to the ID of 16 subbands and DRC.

After the base station receives above-mentioned ACK and DRC information, begin to dispatch the data that need re-transmission.For each user to be retransmitted, at first all available subbands according to DRC sequence arrangement from big to small.Take out this packet transmission plan of last time from memory cell, and, select subband number and coded modulation scheme by this scheme.

For example, certain user's data wrap in and assign to three subbands when transmitting for the first time: subband 1,3 and 10, corresponding DRC is respectively 2,3 and 4.The Turbo code and the QPSK modulation scheme of the code rate of these uniform datas employings 0.58, length is 1792 bits.Notify the ACK=0 of this batch data when corresponding travelling carriage, then the base station retransmits this data.If should retransmit in the professional scheduling specifically, three available subbands of DRC optimum are subbands 2,3 and 9, and corresponding DRC is respectively 3,2 and 3.So this batch data will be still on subband 2,3 and 9 with the Turbo code and the transmission of QPSK modulation scheme of 0.58 code rate, length is 1792 bits.

If when having dispatched the re-transmission user, also have unappropriated subband, then be the non-re-transmission user of unit scheduling with the subband.Each subband will be distributed to the highest user of priority assessment value value on this subband, see formula (1).Having dispatched in this way after all subbands, is that unit transmits with user.Observe subband ID and DRC thereof that each user obtains, the coded modulation parameter of question blank 1, choosing the highest modulation system is the associating modulation parameter.

For example, ID is that 7 user assigns to three subbands: subband 1,3 and 10, corresponding DRC is respectively 2,3 and 4.That supposes that employing table 1 provides carries out the transmission plan of 8 rank quantization thresholds to the subband average signal-to-noise ratio.By tabling look-up our decision on these three subbands, this user's data modulation scheme be max (BPSK, QPSK, QPSK)=QPSK.The data source length of transmission is (256+512+768)=1536 bits.Code rate is 1536/ (3*2*64*8)=1/2.

After all sub-band schedulings finished, AP strengthened protection to the user ID of 16 allocation of subbands and corresponding original DRC information afterwards by notifying each MT on the common down channel.The mode of strengthening protection has the increasing transmitting power, carries out coding protection etc.

MT receives after these information, releases length, position, the coded modulation parameter of useful information with identical process.For example, for user 7, he can learn valid data on subband 1,3 and 10 from control information, and corresponding DRC is respectively 2,3 and 4.Same it can infer out that the code rate of these data is 0.5 by question blank 1, and modulation system is QPSK, and data length is 1536 bits.

Entered final step at last, i.e. statistics and parameter update stage.For above-mentioned ID is 7 user, at this moment will preserve 1536 Bit datas that its this time slot spreads out of, and notes it and has taken 3 subbands, and code rate is 1/2, and modulation system is QPSK.Simultaneously, Len _i=1536, T _c=500 and the R substitution formula (2) of this user's correspondence, obtain and note new parameters R.

Claims (3)

1. the resource regulating method that is used for mistake responsive type business under the OFDM, it is characterized in that: it is that a kind of OFDM of being used for supports down to mix the resource regulating method that feedback automatically retransmits the mistake sensitiveness business of (HARQ) technology, and it distributes corresponding frequency domain sub band resources by following three phases so that taking into account under the principle that reduces the error rate and optimized throughput to each non-real-time service successively:

(1) preparatory stage:

In the fixed schedule cycle, carry out once scheduling at a time slot; It is divided into a subband to plurality of sub carrier wave adjacent in the ofdm system, adopts the identical power division mode of average transmitting power of identical code modulation mode and each subband; As the minimum unit of first resource scheduling, each subband is once only being distributed to a user in the scheduling;

System adopts the closed loop feedback method; Each travelling carriage MT measures the average signal-to-noise ratio SNR of each subband in a time slot, and quantizes the data rate control word DRC that signal to noise ratio obtains correspondence by certain threshold schemes, again according to the time interval of traffic carrying capacity needs decision feedback and the quantity of feedback;

(2) stage of the data of scheduling re-transmission:

Choose and original identical subband number and coded modulation scheme, divide the highest some subbands of DRC of this MT feedback to the user;

(3) stage of the non-re-transmission user data of scheduling:

On each subband of not dispatching, estimate its priority assessment value, each allocation of subbands is given the user of corresponding assessed value maximum; Application has the good throughput of system and the proportional fairness criterion of user fairness on each subband, and the priority assessment value that subband j goes up user i is: $\mathrm{Prio}\_{\mathrm{eval}}_{i,j}=\frac{{\mathrm{Capa}}_{i,j}}{R_i},i=\mathrm{1,2},...,N;j=\mathrm{1,2},...,M,$

Wherein, Capa _{I, j}It is the transmission capacity in the time slot obtaining of the suggestion feedback velocity DRC according to j the subband of user i;

R _iBe the average transmission rate of user i in a period of time, can be represented by the formula:

R _i＝(1-1/T _c)·R _i+Len _i/T _c，i＝1，2，...，N，

T _cBe the adjustable parameter of proportional fairness algorithm the inside, reacted maximum endurable time delay;

Len _iBe to distribute to total transmission capacity that the DRC by travelling carriage feedback of all subband correspondences of the professional i of non-re-transmission tables look-up and obtains in this time slot, can be represented by the formula: ${\mathrm{Len}}_i=\underset{j}{\overset{M}{\mathrm{\Σ}}}{\mathrm{Capa}}_{i,j}\·\mathrm{Slelect}\_{\mathrm{all}}_{i,j},i=\mathrm{1,2},...,N,$

When j subband distributed to i user's assessed value business, Select_all _{I, j}=1, otherwise be zero;

The data aggregate coded modulation of same user on different sub-band adopts the highest modulation system that is proposed on these subbands.

2. the resource regulating method that is used for mistake responsive type business under the OFDM according to claim 1 is characterized in that: in the described scheduling preparatory stage, for the HARQ scheme that adopts Stop And Wait, travelling carriage will feed back to induction signal (ACK) and version information; Have only when ACK be that 0 data just need to retransmit.

3. the resource regulating method that is used for mistake responsive type business under the OFDM according to claim 1 and 2 is characterized in that:

Described dispatching method contains step successively:

(1) information gathering is for formation adds new data and built-in variable initialization;

(2) scheduling needs the data of re-transmission:

(2.1) need to determine the user's of data retransmission number N;

(2.2) the DRC message scheduling data retransmission of the user's that retransmits according to the needs collected of base station travelling carriage feedback:

(2.2.1) for each user to be retransmitted, all available subbands according to DRC rank order from big to small;

(2.2.2) take out this batch data transmission plan of last time from memory cell;

(2.2.3) select for this user and last time same number the highest some subbands of available DRC;

(3) scheduling of non-re-transmission user data:

(3.1) determine the unappropriated number of sub-bands M ' of non-re-transmission user number N ' Buddhist monk to be passed;

(3.2) give the highest user of priority assessment value on respective sub-bands each allocation of subbands.

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