CN101388867B - Resource scheduling method based on OFDM system - Google Patents

Abstract

The invention discloses a resource scheduling method based on orthogonal frequency division multiplexing system used for the OFDM to scheduling the resource of user. While scheduling, grouping the users according to the user applied service type and/or user channel condition; allocating the groups onto the same or different time process; on each time process, only sending the group signaling to the group on the process; allocating the resource to the users in every group using each resource block as a unit; regulating the resource allocated to one group and the user in the group dynamically according to the user resource variation on the next process. The invention adopts different resource scheduling method and different resource scheduling signaling according to the different service type, furthest reduces the signaling cost while ensuring the level of resources utilization the and scheduling flexibility.

Description

A kind of resource regulating method based on ofdm system

Technical field

The present invention relates to system of broadband wireless communication, relate in particular to a kind of resource regulating method based on ofdm system.

Background technology

Orthogonal frequency division multiplex OFDM (Orthogonal Frequency Division Multiplexing) technology is one of main candidate scheme of following wireless communication technology.In frequency domain, given channel is divided into many orthogonal sub-carriers, difference modulation signal on each subcarrier, and each subcarrier parallel transmission.Like this, although the frequency response curve of wireless channel is a non-flat forms, has frequency selectivity; But each subcarrier is a relatively flat; What on each subcarrier, carry out is narrow band transmission, and signal bandwidth is less than channel width, so the just interference between the erasure signal waveform greatly.Because each number of sub-carrier is mutually orthogonal in ofdm system, and their frequency spectrum is overlapped, so not only reduced the phase mutual interference between subcarrier, and the while has been improved the availability of frequency spectrum again.OFDM utilizes inverse discrete fourier transform/DFT (IDFT/DFT) to replace multi-carrier modulation and demodulation in addition, has reduced the complexity of Base-Band Processing.

In ofdm system; Because resource occurs with time and frequency bidimensional, so resource allocation and method for expressing thereof become more complicated, especially bandwidth ratio greatly the time; Should consider the flexibility of resource allocation, consider requirements such as the simple and expense of method for expressing is little again.Method commonly used at present is a definition basic Resource Block RB (Resource Block), is that unit carries out resource allocation then with RB, for example:

Dynamic dispatching method is the time-frequency position by the resource that need take through the user data package transmission each time of signaling hand shaking between user and the base station, though this resource distribution mode has maximum flexibility, signaling consumption is very serious;

Semi-persistent scheduling method is to keep the user to take the time-frequency invariant position of resource within a certain period of time, and to reduce signaling consumption, still this method can cause the level of resources utilization seriously to descend again;

In addition; Also having the dispatching method based on the group form, is that several users are formed one group, and these users' resource allocation signal is combined into a group signaling; User on the same group dispatches simultaneously; This method has reduced signaling consumption to a certain extent, also reduced the scheduling of resource flexibility simultaneously, but this method has very big improvement space.

Summary of the invention

Technical problem to be solved by this invention is, a kind of resource regulating method based on ofdm system is provided, and realizes the scheduling of resource of ofdm system with low signaling consumption, high resource utilization based on block form.

For with lower signaling consumption support scheduling of resource more flexibly; The present invention proposes a kind of efficiently based on the group form resource regulating method; According to the different mining of type of service group resource allocation signal, can reduce signaling consumption and the flexibility that increases resource allocation to greatest extent with different qualities.

The present invention provides a kind of resource regulating method based on ofdm system, and characteristics are:

The user is divided into groups or the user is divided into groups according to the type of service of user applies according to the type of service of user applies and user's channel condition; And each component is fitted on same time course or the different time process; In the group signaling that only issues the group that is assigned on this process on each time course; Be unit with the Resource Block for respectively organizing user resource allocation, and on next process according to the user resources change dynamics adjustment distribute to user's in each group and the group resource.

Wherein, said Resource Block distributes all available subcarriers and obtains, and said each resource block assignments has a logic sequence number and the OFDM symbol of quantity such as comprises, and said each OFDM symbol such as comprises at the subcarrier of quantity.The said subcarrier that belongs in the same Resource Block is continuous or discontinuous physically; Belong to said subcarrier on the different orthogonal frequency division multiplexing symbol in the same Resource Block in identical position or in different positions.

When the user being divided into groups further, according to the type of service of user applies and user's channel condition:

At first according to comprising packet size fluctuation range or occupied bandwidth or the approaching user of traffic performance of the sensitiveness of time being divided into one group;

Secondly, when type of service was identical, the user that channel condition is approaching was divided into one group.

For the bigger group of long data packet fluctuation, for each user in organizing distributes different modulating-coding grades and distributes the different resources that takies;

Less or have the group of fixed service for long data packet fluctuation, adopts constant resource distribution mode, distribute the identical resource that takies unitedly for organizing the user entirely, and dispose unified modulation coding mode.

When the user changes in the group, the total resources that this group takies are adjusted according to resource situation of change in the group.

When user business type or channel condition change in the group, this user's adjustment that changes is switched to corresponding other groups.

If the user need add a certain grouping, need to judge the full rate of group membership of this group, if after adding this user; The full rate of group membership allows this user to add this group less than 1; If after adding this user, the full rate of group membership does not then allow this user to add this group greater than 1; Wherein, the full rate of group membership is defined as:

$\mathrm{GroupMemberFullRatio}=\frac{N_{\mathrm{memberUE}}\·(1+{\mathrm{Ratio}}_{\mathrm{reTrans}})}{(N_{\mathrm{total}\_\mathrm{RB}}/N_{\mathrm{MCS}})\·N_{\mathrm{HARQProcess}}}$

Wherein, N _{Total_RB}Be the Resource Block sum on the time course getting of this component, N _MCSBe this group user number of resource blocks that minimum needs take of once giving out a contract for a project, N _HARQProcessBe mixed automatic retransmission request process number, N _MemberUEBe user's number in the group, Ratio _ReTransIt is retransmission probability.

Adjustment group resource size is confirmed according to the full rate of active period group membership, when idling-resource occurring in this group:

After if judgement reduces the resource occupation sum of this group, the full rate of active period group membership of this group then allows to reduce the resource occupation sum of this group less than 1;

After if judgement reduces the resource occupation sum of this group, the full rate of active period group membership of this group does not then allow to reduce the resource occupation sum of this group greater than 1;

Wherein, the full rate definition of said active period group membership is as follows:

$\mathrm{GroupMemberFullRati}{o}_{\mathrm{Active}}=\frac{N_{\mathrm{ActiveMemberUE}}\·(1+{\mathrm{Ratio}}_{\mathrm{reTrans}})}{(N_{\mathrm{total}\_\mathrm{RB}}/N_{\mathrm{MCS}})\·N_{\mathrm{HARQProcess}}}$

N _{ActiveMemberUE}Be user's number that this group is in active period, N _{Total_RB}Be the Resource Block sum on the time course getting of this component, N _MCSBe this group user number of resource blocks that minimum needs take of once giving out a contract for a project, N _HARQProcessBe mixed automatic retransmission request process number, Ratio _ReTransIt is retransmission probability.

When the user gets into idle periods or retransmission process and finishes in advance, give other users on the same group with the vacant resource allocation of coming out of this user;

When a certain group idling-resource being arranged, idling-resource is distributed to other groups of same time course.

With respect to traditional group scheduling and dynamic dispatching; The present invention has adopted different resources dispatching method and different resources dispatch according to different business types; When fully guaranteeing resource utilization and dispatching flexibility, reduced signaling consumption to greatest extent.In practical application; Type of service is diversified; Traditional group scheduling is not considered the distinctiveness of different business; In the occasion of mixed service, consider that especially user's ratio of the business (for example online game and visual telephone) of VoIP and similar characteristics is in the great majority, traditional group scheduling still can cause the waste of a large amount of signaling fields.And the resource regulating method that the present invention proposes is with respect to traditional group scheduling and dynamic dispatching, and for power system capacity has been brought obvious gain, and the system complexity that increases can be ignored.Simultaneously, user's resource can dynamically be adjusted in group and group, comprises dynamic adjustment CU resource, and adjusting group resource occupation total amount changes adjustment user grouping etc. according to service characteristics, has increased the flexibility of scheduling of resource.

Description of drawings

Fig. 1 is the sketch map of resource allocation piece RB in the embodiment of the invention;

Fig. 2 is the scheduling of resource sketch map of the mixed service of FTP and VoIP in the embodiment of the invention.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is elaborated.

Resource regulating method of the present invention is based on the resource regulating method of group form; According to the type of service of user applies and user's channel condition the user is divided into groups; And each component is fitted on same time course or the different time process, be that unit is for respectively organizing user resource allocation, at the group signaling that only issues the group that is assigned on this process on each time course (resource allocation signal of group form with the Resource Block; The resource allocation information that comprises several users; One group of user only needs a signaling during resource allocation, and its expense is littler than Dynamic Resource Allocation for Multimedia signaling), and on next process, distribute to the resource of respectively organizing the user according to the adjustment of User Status change dynamics.

When carrying out scheduling of resource, resource allocation is to be unit with Resource Block (RB:Resource Block), and each Resource Block RB is composed of a logic sequence number simultaneously.When carrying out the Resource Block division, need be divided into some Resource Block RB to all available subcarriers, contain several OFDM symbols in each Resource Block, the experimental process carrier wave in each OFDM symbol belongs to this Resource Block; Each Resource Block contains identical OFDM symbolic number, and the subcarrier number in each Resource Block in each OFDM symbol is also identical.The subcarrier that belongs in the same OFDM symbol among the same RB can be continuous physically, also can be discontinuous physically; Belonging among the same RB subcarrier on the different OFDM symbols can be in identical position, also can be in different positions.

The base station is that the channel condition according to the type of service of user applies and user divides into groups to the user.In principle, at first consider the approaching user of traffic performance (packet size fluctuation range, occupied bandwidth, to the sensitiveness of time or the like characteristic) is divided at one group, consider that secondly the user that channel condition is approaching divides at one group.For example belong to together among the professional user of VoIP, the user that channel condition is good divides at one group, and the user of bad channel conditions divides at one group, further can be divided into several groups according to the channel condition grade.

Dividing into groups according to traffic performance, when especially the user being divided into groups according to packet size fluctuation range:

The bigger group of long data packet fluctuation can adopt resource distribution mode more flexibly, carries out resource allocation respectively for example for each user;

The less group of the big minor swing of packet can adopt more constant resource distribution mode, and the resource allocation quantity of for example organizing the user entirely is unified, and modulation coding mode is also unified, can under the prerequisite of considering the different demands of different business, reduce signaling consumption fully like this.

These components are fitted on the different time process, on the same process several groups can be arranged.

For each user sets the resource that modulating-coding grade and distribution take; User's on the same group modulating-coding grade and the resource quantity that takies that wherein belongs to the very little or fixing business of the big minor swing of packet is all identical, and the user on the same group who belongs to the bigger business of the big minor swing of packet has different modulating-coding grades and the number of resources that takies respectively.The total resources number that group takies can change, for example when user's adding group newly, leave group, get into idle periods or get back under the situation such as active period, the total resources that the base station can take group are as the case may be adjusted.User's the resource that takies also can change in the group, when for example User Part business or whole business are accomplished, can the free time go out shared resource.

On some time courses, the base station only issues the group signaling of the group that is assigned to this process.

When certain user business type or channel condition change (for example can increase or reduce and judge according to Packet Error Ratio), can it be assigned to other groups by the base station.The user should judge " the full rate of group membership " of this group before adding certain group, define as follows:

$\mathrm{GroupMemberFullRatio}=\frac{N_{\mathrm{memberUE}}\·(1+{\mathrm{Ratio}}_{\mathrm{reTrans}})}{(N_{\mathrm{total}\_\mathrm{RB}}/N_{\mathrm{MCS}})\·N_{\mathrm{HARQProcess}}}$

Wherein, N _{Total_RB}Be the RB sum on the time course getting of this component, N _MCSBe this group user RB number that minimum needs take of once giving out a contract for a project, N _HARQProcessBe HARQ process number (for example maximum retransmission is 3, and then HARQ process number is 4), N _MemberUEBe user's number in the group, Ratio _ReTransIt is retransmission probability.

If newly add feasible " the full rate of group membership "＜1 of access customer, then allow the user to add this group; Otherwise, make " the full rate of group membership "＞1 then do not allow the user to add this group if newly add access customer.

Through above-mentioned judgement, can determine whether to allow new user to add this group to the full rate of group membership.Because can add access customer, number of users in the adjustment group has so just improved the flexibility of dispatching; Simultaneously, through judging the full rate of group membership, cause inadequate resource to produce wrong or other fortuitous event thereby also can avoid blindly adding fashionable meeting, thereby guaranteed the stability of scheduling.

Because the user might get into idle periods in the group, and the duration of idle periods is longer usually, therefore need define one " the full rate of active period group membership " in addition:

$\mathrm{GroupMemberFullRati}{o}_{\mathrm{Active}}=\frac{N_{\mathrm{ActiveMemberUE}}\·(1+{\mathrm{Ratio}}_{\mathrm{reTrans}})}{(N_{\mathrm{total}\_\mathrm{RB}}/N_{\mathrm{MCS}})\·N_{\mathrm{HARQProcess}}}$

Wherein, N _{ActiveMemberUE}It is user's number that this group is in active period.When needs adjustment group resource size, should judge " the full rate of active period group membership ", if a certain group idling-resource occurs, then judge:

Behind the resource occupation sum that reduces this group, " the full rate of active period group membership "＜1 of this group then allows the resource occupation of this group of minimizing total;

If after reducing the resource occupation sum of this group, " the full rate of active period group membership "＞1 of this group does not then allow to reduce the resource occupation sum of this group.

Through judgement to the full rate of active period group membership; Can determine whether adjustment group resource size; Whether decision can reduce the resource occupation sum of this group, so just can the resource that free out in this group be used for other group or user's use, thereby improve resource utilization.

Other users on the same group can be assigned to because the user gets into idle periods or retransmits the resource that finishes to be available in advance,, other groups of same time course can be assigned to if a certain group has idle resource.In this heavy assigning process, the resource location that certain customers take can change, and this is equivalent to have had certain frequency hopping gain.

Embodiment:

FTP (File Transfer Protocol with FDD (the Frequency Division Duplex) system of 3 GPP LTE (Long Term Evolution); FTP) and VoIP (Voice overIntemet Protocol; Internet protocol voice technology) mixed service is an example, supposes that bandwidth is 20MHz, and then number of usable subcarriers is 1200; Contain 14 continuous OFDM symbols in one sub-frame, time span is 1ms.With continuous 12 number of sub-carrier, Resource Block RB of continuous 14 OFDM symbolic representations then contains 100 RB in a sub-frame in the present embodiment.The concrete dividing mode of Resource Block is as shown in Figure 1.

The long data packet that ftp business is uploaded at every turn is unfixing, looks the base station and decides for bandwidth and modulation coding mode that the user distributes, and uplink time is unfixing.

The VoIP business has fixedly frame length (20ms) and fixed data bag size (40Bytes).

Setting maximum retransmission in the present embodiment is 3 times, comprises promptly that first transmission has 4 times and mixes automatic repeat requests HARQ process, adopts synchronous self-adapting HARQ, and twice HARQ process is at a distance of 5 sub-frame.Control channel fixedly takies the resource of 2 and 2 RB in end, and data channel takies the resource of remaining 96 RB.

In the present embodiment, assumed initial state has 2 FTP user, 10 voip users.The group forming criterion that proposes according to the present invention is set the FTP user in the present embodiment and is divided at same group, and the group sequence number is 1; The voip user divides at same group, and the group sequence number is 2.Wherein organize the scheduling mode that 2 all users adopt unified resource number and modulating-coding grade; Adopt scheduling mode flexibly and organize 1, promptly each user has individual resource to take quantity and the control of modulating-coding grade.

Scheduling flow can be with reference to figure 2.The upper of Fig. 2 is the simplification content of the scheduling of resource order of group 1 and group 2.Wherein, The dispatching command of group 1 comprises each user's resource occupation number and modulation coding mode and resource allocation sign (wherein modulation coding mode omits in the drawings, does not mark), and for example " user 1 (38; 1) " representative of consumer 1 has been assigned to 38 RB, allows to take resource.The dispatching command of group 2 only comprises each user's resource allocation sign (the resource occupation number of group 2 and modulation coding mode are unified configuration, and the each data packet transmission of each user in the present embodiment in the setting group 2 takies 2 RB).Following one side of something of Fig. 2 is the corresponding group occupation condition of dispatching command.

In first HARQ process, because group 2 users' business (VoIP) has sensitiveness to the time, the therefore preferential resource requirement (requiring 20 RB altogether) of satisfying group 2 users, surplus resources is by group 1 user's mean allocation.

In second HARQ process; The user that all HARQ of having processes finish in advance in the group 2; Its resource allocation field zero setting, the resource that the free time goes out is selected in the user of all the other resources to be allocated, because group 2 does not have unnecessary wait user; Therefore and the every 20ms of its new packet just upgrades once, organizes the resource that 2 free time went out and is assigned to group 1.

In HARQ process 3, increased a FTP user newly, be assigned in the group 1 according to type of service.Group 1 resource is redistributed by number of users, organizes the resource that 2 free time went out and continues to be taken by group 1.

First HARQ process up to new 20ms arrives, and organizing 2 users has the new data packets request to upload, and need take resource, therefore organizes 1 and discharges the part resource and organize 2 users and redistribute together.

Said HARQ process is a time course; A packet for a user; Its time course that sends the place first just can be called its HARQ process 1; The time course that retransmits the place its first time just can be called its HARQ process 2, and the time course that retransmits the place its second time just can be called its HARQ process 3.

Can clearly find in conjunction with embodiment; The present invention has adopted different resources dispatching method and different resources dispatch according to different business types; When fully guaranteeing resource utilization and dispatching flexibility, reduced signaling consumption to greatest extent.

With respect to traditional group scheduling and dynamic dispatching, the present invention carries out packet scheduling according to type of service to the user; In the user of identical services type, can further carry out packet scheduling according to the difference of channel condition; Group scheduling in different ways for different service types:

Group to " business that the big minor swing of packet is very little or fixing " can be according to the mode scheduling resource (promptly the user adopts unified resource number and modulating-coding grade in the group) than " constant ";

Can adopt the mode scheduling resource of " flexibly " (promptly the interior user of group has different modulating-coding grades and the number of resources that takies respectively) for " business that the big minor swing of packet is bigger ";

The resource of each set of dispense can be redistributed according to different idle condition, increases scheduling of resource flexibility and resource utilization, and the reprovision process can simply be accomplished not extra increase signaling consumption through the group signaling.User's resource occupation position all can change behind each reprovision, is equivalent to have certain frequency hopping gain.

Simultaneously, also allow the user to switch to other groups among the present invention; Through increasing the definition of " the full rate of group membership " and " the full rate of active period group membership ", provide auxiliary to user's switch groups.

In practical application; Type of service is diversified; Traditional group scheduling is not considered the distinctiveness of different business; In the occasion of mixed service, consider that especially user's ratio of the business (for example online game and visual telephone) of VoIP and similar characteristics is in the great majority, traditional group scheduling still can cause the waste of a large amount of signaling fields.With respect to traditional group scheduling and dynamic dispatching, the resource regulating method that the present invention proposes will bring obvious gain for power system capacity, and the system complexity that increases can be ignored.

The preferred embodiments of the present invention that are merely described herein; Be not limited to the present invention; Certainly, the present invention also can have other various embodiments, under the situation that does not deviate from spirit of the present invention and essence thereof; Those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.

Claims (10)

1. resource regulating method based on ofdm system is characterized in that:

According to the type of service of user applies and/or user's channel condition the user is divided into groups; And each component is fitted on same time course or the different time process; In the group signaling that only issues the group that is assigned on this process on each time course; Be unit with the Resource Block for respectively organizing user resource allocation, and on next process according to the user resources change dynamics adjustment distribute to user's in each group and the group resource.

2. resource regulating method as claimed in claim 1; It is characterized in that; Said Resource Block distributes all available subcarriers and obtains; Said each resource block assignments has a logic sequence number and the OFDM symbol of quantity such as comprises, and said each OFDM symbol such as comprises at the subcarrier of quantity.

3. resource regulating method as claimed in claim 2 is characterized in that, the said subcarrier that belongs in the same Resource Block is continuous or discontinuous physically; Belong to said subcarrier on the different orthogonal frequency division multiplexing symbol in the same Resource Block in identical position or in different positions.

4. resource regulating method as claimed in claim 1 is characterized in that, when the user being divided into groups according to the type of service of user applies and/or user's channel condition:

At first according to comprising packet size fluctuation range or occupied bandwidth or the approaching user of traffic performance of the sensitiveness of time being divided into one group;

Secondly, when type of service was identical, the user that channel condition is approaching was divided into one group.

5. resource regulating method as claimed in claim 4 is characterized in that:

For the bigger group of long data packet fluctuation, for each user in organizing distributes different modulating-coding grades and distributes the different resources that takies;

Less or have the group of fixed service for long data packet fluctuation, adopts constant resource distribution mode, distribute the identical resource that takies unitedly for organizing the user entirely, and dispose unified modulation coding mode.

6. resource regulating method as claimed in claim 5 is characterized in that:

When the user changes in the group, the total resources that this group takies are adjusted according to resource situation of change in the group.

7. resource regulating method as claimed in claim 5 is characterized in that:

When user business type or channel condition change in the group, this user's adjustment that changes is switched to corresponding other groups.

8. like claim 6 or 7 described resource regulating methods, it is characterized in that:

If the user need add a certain grouping, need to judge the full rate of group membership of this group, if after adding this user; The full rate of group membership allows this user to add this group less than 1; If after adding this user, the full rate of group membership does not then allow this user to add this group greater than 1; Wherein, the full rate of group membership is defined as:

$\mathrm{GroupMemberFullRatio}=\frac{N_{\mathrm{memberUE}}\·(1+{\mathrm{Ratio}}_{\mathrm{reTrans}})}{(N_{\mathrm{total}\_\mathrm{RB}}/N_{\mathrm{MCS}})\·N_{\mathrm{HARQProcess}}}$

Wherein, N _{Total_RB}Be the Resource Block sum on the time course getting of this component, N _MCSBe this group user number of resource blocks that minimum needs take of once giving out a contract for a project, N _HARQProcessBe mixed automatic retransmission request process number, N _MemberUEBe user's number in the group, Ratio _ReTransIt is retransmission probability.

9. resource regulating method as claimed in claim 7 is characterized in that:

Adjustment group resource size is confirmed according to the full rate of active period group membership, when idling-resource occurring in this group:

After if judgement reduces the resource occupation sum of this group, the full rate of active period group membership of this group then allows to reduce the resource occupation sum of this group less than 1;

After if judgement reduces the resource occupation sum of this group, the full rate of active period group membership of this group does not then allow to reduce the resource occupation sum of this group greater than 1;

Wherein, the full rate definition of said active period group membership is as follows:

${\mathrm{GroupMemberFullRatio}}_{\mathrm{Active}}=\frac{N_{\mathrm{ActiveMemberUE}}\·(1+{\mathrm{Ratio}}_{\mathrm{reTrans}})}{(N_{\mathrm{total}\_\mathrm{RB}}/N_{\mathrm{MCS}})\·N_{\mathrm{HARQProcess}}}$

N _{ActiveMemberUE}Be user's number that this group is in active period, N _{Total_RB}Be the Resource Block sum on the time course getting of this component, N _MCSBe this group user number of resource blocks that minimum needs take of once giving out a contract for a project, N _HARQProcessBe mixed automatic retransmission request process number, Ratio _ReTransIt is retransmission probability.

10. resource regulating method as claimed in claim 7 is characterized in that:

When the user gets into idle periods or retransmission process and finishes in advance, give other users on the same group with the vacant resource allocation of coming out of this user;

When a certain group idling-resource being arranged, idling-resource is distributed to other groups of same time course.

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