CN101567834A - Radio resource scheduling method with ensured time delay for mobile communication system - Google Patents

Abstract

The invention relates to a downlink radio resource scheduling method of a mobile communication orthogonal frequency division multiplexing OFDM system, which uses a superior average speed updating mechanism and a cumulated service time delay index so that the mobile communication orthogonal frequency division multiplexing OFDM system ensures the service time delay and the user fairness under the condition that the capacity of the mobile communication orthogonal frequency division multiplexing OFDM system keeps high throughout. The invention optimizes a high-speed and multi-service system, thereby greatly enhancing the system performance.

Description

Mobile communication system has the scheduling method for wireless resource that time delay guarantees

Technical field

The present invention relates to mobile communication ofdm system scheduling method for wireless resource, be specifically related to the packet radio dispatching algorithm of downlink traffic.

Background technology

OFDM is a kind of sound communication technology of carrying out the effective information transmission in channel.Because the raising of data rate is for the user provides the multiple business service.Therefore, the following scheduling method for wireless resource that can satisfy QoS requirement of high data rate becomes key one ring of realizing the whole system performance.

In the present wireless resource scheduling algorithm, a class is the algorithm of amplifying radio conditions from traditional wired packet scheduling algorithm, and another kind of is the algorithm of pursuing the throughput of system maximization.The former has but ignored quality of service requirement when ensureing fairness, actual effect is undesirable.The latter is guaranteeing that big defective is arranged on time delay and the fairness.

For mobile service service provider, wireless bandwidth resource is limited, and can not ignore quality of services for users.Therefore, how guaranteeing service delay and user fairness under the prerequisite of pursuing the throughput of system maximization, is subject matter to be solved by this invention.

Summary of the invention

The object of the present invention is to provide the method for the wireless resource scheduling that has the time delay assurance in a kind of ofdm system.

To achieve these goals, have the scheduling method for wireless resource that time delay guarantees in a kind of ofdm system, comprise step:

(1) business is carried out classification, the definition priority level enters step (2).

(2) obtain the service request situation of M user's current time slots, enter step (3).

(3) obtain the quantity N of system's current available resource piece, enter step (4).

(4) calculate the predicted velocity V (t) of each user on each Resource Block according to channel feedback information, enter step (5).

(5) calculate each user and accumulate service index λ (t), enter step (6).

(6) calculate priority P=λ (t) V (the t)/U (t) of each user on each Resource Block, enter step (7).

(7) priority of each user on each Resource Block is sorted, enter step (8).

(8) whether the user according to prioritization situation inspection priority maximum on this Resource Block is leading stream, if then enter step (9), is not then to enter step (10).

(9) each after flow user is sorted in the enterprising row major level of this Resource Block, enter step (10).

(10) select the maximum user of priority to distribute this Resource Block to each Resource Block.Enter step (11).

(11) judge whether whole Resource Block assign, distribute and then enter step (12), unallocated intact then repeating step (8) on next Resource Block.

(12) renewal user's Mean Speed U (t).Enter step (13).

(13) scheduling of resource of end current time slots.

The present invention is technical the equitable proportion characteristic, serves parameters such as time delay index by Mean Speed, the accumulative total of adjusting the transmission data, to the restriction of service time delay, promotes quality of service characteristics under the realization high-throughput.Utilize user's service flow to obtain the aggregate-value of service again, realize the mutual compensation of each customer flow, embody long-term fairness.

Description of drawings

The operational flowchart that Fig. 1 determines for the present invention.

Fig. 2 is each service priority figure of user.

Fig. 3 is ofdm system resource block structures figure.

Embodiment

At length describe the present invention below in conjunction with accompanying drawing:

Fig. 2 carries out classification for customer service according to its quality of service requirement difference.Define 4 kinds of different service priority: with VoIP is that typical conversational class QoS rank is 0; With the VOD video request program is that typical stream class service levels of quality of service is 1; With the WWW web page browsing, database retrieval is that typical interaction service levels of quality of service is 2; Is 3 with E-mail, FTP etc. for the levels of quality of service of typical background business.

Fig. 3 is the ofdm system resource symbol, and the Resource Block that the present invention adopts be the minimum resource allocation unit that is made up of subcarrier in frequency domain bunch and time slot, and each is dispatched frame employing Resource Block, user-dependent decision method.

As shown in Figure 1, the base station at first obtains the request situation of M user to Resource Block, reading system current available resource piece N then at current time.Adopt the mode of Limited Feedback, user's different channels situation is adopted from QPSK1/3 to the different modulation coding mode of 16QAM4/5 speed.

Definition user i prediction data speed on Resource Block j is

V _ij(t)＝N _sd(t)/T _f?1≤i≤M?1≤j≤N

In the formula: N _sThe OFDM symbolic number that comprises for Resource Block; D (t) is the modulating-coding exponent number; T _fBe scheduling frame time length; M is a number of users in the system; N is can be for the Resource Block quantity of user's use.

After N time slot scheduling, the expectation that user i can obtain speed is:

$U_i\left(t\right)=\frac{1}{T_N}\underset{N}{\mathrm{\Σ}}{r}_i$

T wherein _N=NT _fBe the equitable proportion length of window, The volume of services sum that receives in N time slot scheduling in the past for user i.

System safeguards a starvation time counter S for each user _i(t), statistics user i has had at moment t and how long has not received service.

$\left\{\begin{array}{cc}{S}_i(t+1)=S_i\left(t\right)\×I_{Q\left(V^{t+1}\right)\≠i}+I_{Q\left(V^{t+1}\right)\≠i}& t\≥0\\ S_i\left(0\right)=I_{Q\left(V^o\right)=i}& \end{array}\right.$

Wherein,

Situation 1:S _i(t)＜T _i, T _iHunger warning thresholding for user i adopts normal mode to upgrade Mean Speed.

Situation 2:S _i(t) 〉=T _i, then adopt and adjust accumulation service time delay index λ _i(t) mode is dispatched, and obtains service to guarantee user j as early as possible before reaching the warning thresholding.Accumulation service time delay index λ _i(t) the adjustment mode is as follows:

${\mathrm{\&lambda;}}_i\left(t\right)=\left\{\begin{array}{cc}1& S_i<T_i\\ \exp \left(\frac{S_i\left(t\right)-T_i}{T_s}\right)& S_i\&GreaterEqual;T_i\end{array}\right.$

T wherein _sFor delay parameter can be set.

This moment, the update mode of user's Mean Speed was divided into two kinds of situations:

1) if at nearest T _iThe shake of observation user Mean Speed surpasses threshold value σ in time, shows that then great variety has taken place suddenly subscriber channel, and this moment should be with the historical information U of user i Mean Speed _i(t) zero clearing, with it according to the processing that Adds User, to guarantee competitiveness and the fairness of user i under this scheduling rule.

2) if at nearest T _iThe shake of observation user Mean Speed does not surpass threshold value σ in time, illustrates that it is because other subscriber channel situations are better that the user does not obtain service, is not that the channel quality degrades of user own causes, and it is constant that upgrade the Mean Speed mode this moment.

Leading stream compensates voluntarily to after flow, and miscellaneous service is respectively according to the ratio of the different compensation of priority

With

Wherein ${\&PartialD;}_0\&le;{\&PartialD;}_1\&le;{\&PartialD;}_2\&le;{\&PartialD;}_3\&Element;\left(\mathrm{0,1}\right).$

The priority selection strategy of condition monitoring Proportional Fair algorithm definition user i on Resource Block j is

$P_{\mathrm{ij}}{=\mathrm{\&lambda;}}_i\left(t\right)\frac{V_{\mathrm{ij}}\left(t\right)}{U_i\left(t\right)}$

Scheduling rule selects the user as follows:

Scheduling rule is selected the user

$k=\underset{1\&le;i\&le;M,1\&le;j\&le;N_r}{\arg \max }{p}_{\mathrm{ij}}\left(t\right)$

Detect whether user k is leading stream

If the user is not leading stream, then distributes resource blocks j gives user k; If be leading stream, then user k abdicates the user that Resource Block j gives after flow according to ratio.Use scheduling rule to select the after flow user

$k^{\&prime;}=\underset{1\&le;i\&le;M^{\&prime;},1\&le;j\&le;{N^{\&prime;}}_r}{\arg \max }{p}_{\mathrm{ij}}\left(t\right)$

User k is according to service conditions using compensation ratio After flow user k ' is compensated.

Claims (6)

1, a kind of based on ofdm system downlink radio resource dispatching method, when the multiple business data flow of different user was lined up in the base station, the scheduling strategy of traffic packets contained following a few step:

Service quality graded definition

The current peak transfer rate of predictive user

User's Mean Speed method for updating

The user accumulates the computational methods of service time delay index

Selection to the user of current distributes resource blocks

2, dispatching method according to claim 1 is wherein before the transport service, to other definition of QoS level.

3, dispatching method according to claim 1 is to the prediction of all user's peak transfer rates.

4, dispatching method according to claim 1 is to the renewal of all user's Mean Speeds.

5, dispatching method according to claim 1 is served the calculating of time delay index to all users accumulative total.

6, dispatching method according to claim 1 is selected the user in the current time Resources allocation.

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