CN102625316A - A Distributed Coordinated Scheduling Method with Random Backoff - Google Patents

Abstract

The invention provides a random back-off distributed coordination scheduling method, which includes independently scheduling users in every sector through a proportional fair scheduling principle; selecting coordination sectors according to types of scheduled users, namely, users in sectors or users at the edge of sectors; broadcasting own scheduling information to the coordination sectors after finishing the independent scheduling and determining the coordination sectors through every sector; and processing scheduling conflicts among sectors through a random back-off interference coordination mechanism to perform scheduling coordination among sectors, based on the scheduling information of the own sector and other sectors. According to the random back-off distributed coordination scheduling method, the distributed processing of coordination scheduling is achieved and can be achieved in existing network structures, and the performance of users at the edge of sectors is improved greatly.

Description

A Distributed Coordinated Scheduling Method with Random Backoff

technical field

The invention belongs to the technical field of wireless communication, in particular to a distributed coordination scheduling technology of random backoff.

Background technique

In order to make full use of limited spectrum resources, a full frequency reuse scheme is adopted. However, when the network adopts full frequency reuse, the system is in a state of limited interference, especially for cell edge users. In order to eliminate the interference of users and improve the spectrum efficiency of the cell and the spectrum efficiency of the users at the edge of the cell, a coordinated scheduling technique is proposed. That is, multiple cells work together to eliminate interference to other cells. Since the coordinated scheduling technology requires joint processing and joint optimization between cells, a large amount of information interaction between cells is required, and a central node is required to handle coordination and other issues, which is difficult to achieve under the existing network architecture.

Contents of the invention

The purpose of the present invention is to overcome the problem that the existing coordinated scheduling technology needs global optimization, in order to realize the coordinated scheduling technology under the existing network architecture, overcome the large amount of information interaction between the cells brought about by the coordinated scheduling technology, and the whole network For the optimization problem, a distributed coordinated scheduling method based on random backoff is proposed, which improves the spectral efficiency of cell edge users while ensuring the average spectral efficiency of the cell.

To achieve the above object, the present invention adopts the following technical solutions:

(1) Each site uses the principle of proportional fair scheduling to independently schedule users in each sector of the cell, and each resource block in the same sector can only be allocated to one user;

(2) Divide independently scheduled users into sector center users and sector edge users, and use coordinated scheduling technology to select the cooperative sector required for coordinated scheduling for sector edge users;

(3) After the cooperative sector is determined, the cell broadcasts the shared cooperation information to the cell where the coordinated sector is located;

(4) After each station receives the cooperation information shared by the neighboring cells, if the neighboring cells have a cooperation request for the sector on the resource block, then determine whether the scheduled user on the resource block is a sector-edge user, if yes Users at the edge of the sector will back off with random probability, and users at the center of the sector will back off from the sector.

The concrete method of described step (1) is as follows:

For any time t, any cell n, the resource block i of the cell at this time is allocated to user k ^* , k ^* is determined by the following formula:

${\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; max</span>}}\frac{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; k\; n</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}$

, _rkn (t) represents the maximum transmission rate of user k on cell n, T _k represents the total historical throughput of user k, after resource block allocation at each moment, the historical throughput is calculated according to T _k =T _k +r _kn (t) update, repeat the above process until all sector resources are allocated, use I _s (k, i) to represent the resource allocation indicator factor of sector s, and I _s (k, i)=1 to represent the sector s i resource blocks are allocated to user k, and I _s (k, i)=0 means that the i th resource block of sector s is not allocated to user k.

The concrete method of described step (2) is as follows:

(2-1) Classification rules for user categories

时，判定用户k为扇区边缘用户，当用户k满足

时，判定用户k为扇区中心用户，

表示用户k平均接收信干噪比，γ_thr为边缘用户判定阈值，该阈值可通过扇区边缘用户的比例来确定；When user k satisfies

, it is determined that user k is a sector edge user, when user k satisfies

When , it is determined that user k is the sector center user,

Indicates the average received signal-to-interference-noise ratio of user k, and γ _thr is the decision threshold of edge users, which can be determined by the proportion of sector edge users;

(2-2) Selection of collaboration type

Classify the user k ^* selected in step (1) according to the division rules in (2-1). If user k ^* is a sector center user, a non-cooperative transmission scheme is adopted, and only the local station transmits data for it. If user k ^* is a sector edge user, the coordinated scheduling transmission scheme is adopted;

(2-3) Selection of cooperative sectors in coordinated scheduling

If user k ^* adopts the coordinated scheduling transmission scheme, then user k ^* selects the two sectors with the strongest interference signals in all cells as the cooperative sectors in coordinated scheduling

The concrete method of described step (3) is as follows:

表示小区b中协作扇区包含扇区

的用户集合，若表示站点b在第i个资源块上需要扇区

的协作，若

表示站点b在第i个资源块上不需要扇区

的协作，设扇区所属站点为

则站点b向站点

共享协作信息的方法就是将

发送给站点

make

Indicates that the cooperative sector in cell b includes the sector

set of users, if Indicates that site b needs a sector on the i-th resource block

cooperation, if

Indicates that site b does not need sectors on the i-th resource block

Collaboration, Sector The site is

site b to site

The way to share collaborative information is to

send to site

The concrete method of described step (4) is as follows:

i. Initialization:

表示站点

收到的所有针对扇区

的共享协作信息，

表示所有需要扇区

协作的站点集合；make i=1, then enter step ii,

Indicates the site

All received against sector

shared collaboration information,

Indicates all required sectors

Collaborative collection of sites;

有协作请求：ii. Judging whether there is an adjacent site on the resource block i for the sector

There is a collaboration request:

表示有协作需求，进入步骤iii，若

表示无协作需求，进入步骤v；like

Indicates that there is a need for collaboration, go to step iii, if

Indicates that there is no need for collaboration, go to step v;

资源块i上调度的用户k^*是否为扇区边缘用户：iii. Judging sectors

Whether user k ^* scheduled on resource block i is a sector edge user:

用户k^*从扇区

的资源上块i退避以降低干扰，进入步骤v；If it is a sector edge user, go to step iv; if it is a sector center user, make

user k ^* slave sector

Back off block i on the resources to reduce interference, enter step v;

的概率退避：iv. Cell edge users use

The probability backoff of :

的资源块i上退避，进入步骤v；若直接进入步骤v；P_thr表示表示存在1个协作需求时，用户从相应资源块退避的概率；Generate a (0, 1) uniformly distributed random number tempVal, if order user k ^* slave sector

Back off on the resource block i of , go to step v; if Go directly to step v; P _thr represents the probability that the user backs off from the corresponding resource block when there is one collaboration demand;

v. Make i=i+1, if i≤N, then return to step ii to coordinate the next resource block;

的调度协调，N表示资源块的总数。If i>N, end sector

Scheduling coordination, N represents the total number of resource blocks.

The present invention has the following beneficial effects: firstly, the present invention independently schedules each cell, selects the scheduled user, and determines its cooperative cell by the type of the scheduled user. Then broadcast the scheduling information and request cooperation information, and finally deal with the conflict of scheduling information between cells through the back-off mechanism. Avoiding the introduction of central nodes can be realized under the existing network architecture.

Specific implementation method

The present invention will be further described below in conjunction with embodiment.

The core idea of the present invention is: due to full frequency multiplexing, users at the edge of the cell are severely interfered and have poor performance, so a coordinated scheduling technique is proposed. However, the realization of coordinated scheduling technology requires global optimization and central node scheduling, which is difficult to achieve under the existing framework. In order to overcome the above problems, we propose a distributed coordinated scheduling technology with random backoff. Each cell independently schedules users in the cell, and then broadcasts its own scheduling information and coordination requests to surrounding cells. According to its own scheduling information and the scheduling information of other cells, if a scheduling conflict occurs, the cell will use an adaptive random backoff technology to complete the conflict coordination. Avoid using a central node so that each cell can complete its scheduling independently.

Example

User MIMO cell, the cell includes B cells (one cell corresponds to one site), each cell is divided into 3 sectors, each sector distributes the same users, the coordinated scheduling technology is used between the cells to eliminate the difference between the cells interfering. Include the following steps:

(1) Independent scheduling within the sector;

(2) Selection of the cooperative sector;

(3) Scheduling information sharing among cooperative cells;

(4) Scheduling and coordination between cells;

Specific steps are as follows:

(1) Independent scheduling within the sector, the specific steps are as follows:

Each site independently schedules the users in the cell, and the scheduling scheme is proportional fair scheduling. The scheme is as follows.

Intra-cell proportional fair scheduling strategy: For any time t and any cell n, the resource block i of the cell at this time is allocated to user k ^* , and k ^* is determined by the following formula:

${\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; arg</span>}\mathrm{<span\; class="notranslate">\; max</span>}}\frac{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; k\; n</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}$

, r _kn (t) represents the maximum transmission rate of user k in cell n, and T _k represents the total historical throughput of user k. After the allocation of resource blocks at each moment, the historical throughput needs to be updated, that is, T _k =T _k + r _kn (t). In order to ensure the orthogonality in the cell, each resource block in the same sector can only be allocated to one user. Repeat the above process until all resources (three sectors) are allocated. May wish to use I _s (k, i) to represent the resource allocation indicator factor of sector s, if I _s (k, i) = 1, it means that the i-th resource block of sector s is allocated to user k, otherwise I _s (k , i)=0 means not assigned to the user.

(2) The selection of the cooperation sector, the specific steps are as follows:

Step 1: Classify the users k ^* selected by proportional fair scheduling in the cell

当用户k满足时，则判定为小区边缘用户，否则判定为扇区内用户。其中γ_thr为边缘用户判定阈值。In the present invention, there are two types of users: intra-sector users and sector-edge users. The user mainly determines its type according to the average received SINR of the pilot signal. Suppose the average received SINR of user k is

When user k satisfies , it is determined as a cell edge user, otherwise it is determined as an intra-sector user. Where γ _thr is the edge user decision threshold.

Step 2: Different types of users adopt different transmission schemes

If the user is an intra-sector user, a non-cooperative transmission scheme is adopted, and only the serving node transmits data for it. If user k is a sector-edge user, the user selects the two sectors with the strongest received signals in all cells to join its coordination set.

(3) Scheduling information sharing between cooperative cells, the specific steps are as follows:

表示小区b中协作集合包含扇区的所有用户集合，令

显然，若则表示站点b在第i个资源块上需要扇区

的协作，否则表示没有协作需求。设扇区

所属站点为

则站点b与站点

共享调度信息的方法就是将

发送给站点 After the scheduling is completed, each station will send the resource allocation plan of the corresponding cooperative user in the cell to the station where the cooperative sector selected by the local user is located. use

Indicates that the cooperation set in cell b contains sectors The set of all users of , let

Obviously, if It means that station b needs a sector on the i-th resource block

cooperation, otherwise Indicates that there is no collaboration requirement. Sector

The site is

Then site b and site

The way to share scheduling information is to

send to site

(4) Scheduling and coordination between cells, the specific steps are as follows:

扇区为例，在收到所有针对扇区

的共享调度信息

其中

表示所有需要扇区

协作站点)后，对本扇区内的调度方案按照随机退避方法进行协调，具体步骤如下：After each site receives the scheduling information shared by neighboring cells, it coordinates the scheduling of its own cell based on it, so as to realize cooperation. by site

sector As an example, after receiving all

Shared scheduling information for

in

Indicates all required sectors

After coordinating sites), the scheduling scheme in this sector is coordinated according to the random backoff method, and the specific steps are as follows:

进入步骤ii。i. Initialization: command

Go to step ii.

有协作请求：若

则表示有协作需求，进入步骤iii；否则，进入步骤v。ii. Judging whether there is an adjacent site on the resource block n sector

There is a collaboration request: if

If there is a need for collaboration, go to step iii; otherwise, go to step v.

资源块n上调度的用户k^*是否为小区边缘用户：若为小区边缘用户，则进入步骤iv；否则，用户k^*从该资源上退避以降低干扰，即令

进入步骤v。iii. Judging sectors

Whether user k ^* scheduled on resource block n is a cell-edge user: if it is a cell-edge user, go to step iv; otherwise, user k ^* retreats from the resource to reduce interference, that is,

Go to step v.

则用户k^*从该资源上退避，即令

进入步骤v；否则，直接进入步骤v 。iv. Cell edge users use Probabilistic backoff: Generate a (0, 1) uniformly distributed random number tempVal, if

Then user k ^* backs off from the resource, that is,

Go to step v; otherwise, go directly to step v.

v. Let n=n+1, if n≤N, go back to step ii to coordinate the next resource block; otherwise, end the scheduling coordination of this sector.

In the above algorithm, we adopt a random backoff mechanism for cell edge users, where _Pthr represents the probability of users backing off from the corresponding resource block when there is one coordination demand (its value can be determined empirically). According to the above algorithm, if there are multiple nodes requesting cooperation on this resource block, the probability that users in the cooperative sector will back off from this resource block increases, which is reasonable, because the transmission on this resource block will give multiple peers Users in adjacent cells cause serious interference, so the gain brought by backoff is more obvious. The purpose of adopting the random backoff mechanism for the cell edge users is to prevent both cooperating parties from backing off at the same time, resulting in waste of resources.

Claims (5)

1. the distributed coordination dispatching method of a random back is characterized in that, may further comprise the steps:

(1) each website proportion of utilization equity dispatching principle is in each sector independence dispatched users of this sub-district, and each Resource Block can only be distributed to a user in the same sector;

(2) user after the independent scheduling is divided into sector central user and sector-edge user, adopts the coordinated scheduling technology to be the needed cooperation of sector-edge user selection coordinated scheduling sector;

(3) behind definite sector of cooperating, by the Cell Broadcast CB shared collaboration information of this sub-district to place, cooperation sector;

(4) each website is after receiving the cooperative information that neighbor cell is shared; If neighbor cell has the cooperation request to the sector on Resource Block; Judge then whether the dispatched users on the Resource Block is sector-edge user, if sector-edge user is then carried out random chance and kept out of the way; If the sector central user is then kept out of the way from the sector.

2. according to the distributed coordination dispatching method of the said a kind of random back of claim 1, it is characterized in that: the concrete grammar of said step (1) is following:

To any time t, arbitrary cells n distributes to user k with the Resource Block i of this this sub-district of moment ^*, k ^*Confirm by following formula:

$k^{*}=\underset{k}{\arg \max }\frac{r_{\mathrm{kn}}\left(t\right)}{T_k}$

, r _Kn(t) peak transfer rate of expression user k on the n of sub-district, T _kThe historical total throughout of expression user k after each resource block assignments constantly, is pressed T to historical throughput _k=T _k+ r _Kn(t) upgrade, repeat said process and assign, use I up to all sector resources _s(k, i) the resource allocation indicator of expression sector s, I _s(k, i)=1 i the resource block assignments of expression sector s given user k, I _s(k, i)=the 0 unallocated user k that gives of i the Resource Block of expression sector s.

3. according to the distributed coordination dispatching method of the said a kind of random back of claim 1, it is characterized in that: the concrete grammar of said step (2) is following:

(2-1) division rule of class of subscriber

When user k satisfies

The time, judge that user k is a sector-edge user, when user k satisfies

The time, judge that user k is the sector central user, Expression user k average received Signal to Interference plus Noise Ratio, γ _ThrBe the edge customer decision threshold;

(2-2) selection of cooperation type

With the user k that selects in the step (1) ^*Division rule according in (2-1) is classified, if user k ^*Be the sector central user, then adopt non-cooperation transmission scheme, only site-local is for its transmission data, if user k ^*Be sector-edge user, then adopt the coordinated scheduling transmission plan;

(2-3) selection of cooperation sector in the coordinated scheduling

If user k ^*Adopt the coordinated scheduling transmission plan, then user k ^*In all sub-districts, select 2 the strongest sectors of interference signal as the cooperation sector in the coordinated scheduling

4. according to the distributed coordination dispatching method of the said a kind of random back of claim 1, it is characterized in that: the concrete grammar of said step (3) is following:

Make the sector of cooperating among

expression sub-district b comprise user's set of sector

; If

expression website b needs the cooperation of sector

on i Resource Block; If

expression website b does not need the cooperation of sector

on i Resource Block, establish that website is

under the sector

then website b exactly

sent to website to the method for website

shared collaboration information

5. according to the distributed coordination dispatching method of the said a kind of random back of claim 1, it is characterized in that: the concrete grammar of said step (4) is following:

I. initialization:

Make i=1; Get into step I i then; All shared collaboration information that

expression website

is received to sector

,

representes the Website Hosting that all need sector

cooperation;

Ii. judged whether that adjacent sites has the cooperation request to sector

on Resource Block i:

If

expression has collaborative demand; Get into step I ii; If the no collaborative demand of

expression gets into step v;

Iii. judge the sector

Resource Block i goes up the user k of scheduling ^*Whether be sector-edge user:

If sector-edge user then gets into step I v; If the sector central user, order User k ^*From the sector

Resource on piece i keep out of the way reduce to disturb, get into step v;

Iv. Cell Edge User is kept out of the way with the probability of

:

Generate (0, a 1) equally distributed random number tempVal, if

Then order

User k ^*From the sector

Resource Block i on keep out of the way, get into step v; If

Directly get into step v; P _ThrWhen there is 1 collaborative demand in the expression expression, the probability that the user keeps out of the way from the respective resources piece;

V. make i=i+1, if i≤N then gets back to step I i next Resource Block is coordinated;

If i＞N; Finish the scheduling of sector

and coordinate, N representes the sum of Resource Block.