KR100594518B1 - Apparatus and method for scheduling data transmission in communication system - Google Patents

Abstract

Disclosed are a scheduling apparatus and method for simultaneously considering a service level for each subscriber and a wireless channel environment in a wireless communication environment. That is, in the data transmission scheduling apparatus of the communication system according to the present invention, the variable according to the service class assigned to the terminal is a first priority adjustment variable, and the received power change variable of the terminal is a second priority adjustment variable. It characterized in that it comprises a PF (Proportional Fairness) scheduler.

In addition, the data transmission scheduling method in the communication system according to the present invention, the data transmission scheduling method from the communication system to the terminal, comprising: setting the priority through the Proportional Fairness (PF) scheduling; Resetting the final priority in consideration of the priority adjustment variable with respect to the priority set in the above; And allocating data according to the reset priority, so that data can be efficiently transmitted even with a sudden change in a wireless channel environment while meeting a service grade required for each user.

PF scheduler, priority, class of service, received power

Description

Data transmission scheduling apparatus and method in communication system {Data Transmission Scheduling Apparatus and Method in the Communication System}

1 is a view showing a change over time of a general terminal reception power.

2 is a diagram illustrating priority adjustment variables in the form of an exponential function of the present invention.

Figure 3 shows a priority adjustment variable in the form of a symmetric function of the present invention.

4 is a schematic diagram illustrating a scheduler in accordance with the present invention.

                    * Explanation of Codes on Major Parts of Drawings *

400: scheduler 410: first operation unit

420: second operation unit 430: memory

440: priority assignment unit

The present invention relates to a communication system, and more particularly, to an apparatus and method for data transmission scheduling in a wireless channel environment that changes in time.

Generally, in order to maximize communication system throughput, all resources are allocated to a user having the maximum signal power to noise power ratio (C / I). However, using this scheduling algorithm, only a few users in a good environment (high signal-to-noise-to-noise ratio (C / I)) can monopolize the resource, which is why most other The user does not communicate at all.

In order to solve this problem, if the same transmission opportunity is given to all users, the resource share of the entire user will always be the same, but the overall system throughput will be very low.

In wireless communication, the error probability of transmission data varies according to the environment of the wireless channel, so the average transmission rate does not reach the speed of data that can be supported in the physical layer. Therefore, in order to overcome such phenomena, a PF Scheduling (Proportional Fairness Scheduling) method has been proposed.

In the PF scheduling method, the priority is determined by a ratio of the average data rate from the n-th time duration to the (n-1) th time period with respect to the required data rate. Send the data of the high active user. This is explained in more detail.

The priority function of the kth active user is expressed by Equation (1) below.

는 k번째 활성 사용자의 우선순위 함수를 나타내고,

은 k번째 활성 사용자에 대해 다음 번 시구간에서 지원되는 데이터 전송률(데이터량),

은 활성 사용자의 단말로부터 수신된 요구 데이터 전송률(데이터 요구량),은 전송구간

동안 전송해야 할 데이터 전송률을 나타낸다.here,

Represents the priority function of the kth active user,

Is the supported data rate (data amount) for the next time period for the kth active user,

Is the requested data rate (data demand amount) received from the terminal of the active user, is the transmission interval

Indicates the data rate that should be transmitted during.

은 다음 수학식(2)와 같이 표현된다.At this time,

Is expressed by the following equation (2).

은 지난번 시구간까지 전송된 데이터의 평균 전송률로써 다음 수학식(3)과 같이 표현된다. On the other hand, of the formula (1)

Is the average data rate of the data transmitted up to the last time interval and is expressed as in Equation (3) below.

는 상기 데이터의 평균 전송률이 고려되는 시구간을,

은 그 기간동안에 실제 전송된 데이터의 전송률을 나타낸다. 따라서, 우선순위 함수는 k번째 활성사용자에 대해 다음 번 시간에서 지원되는 데이터 전송률 대비 지난번 시구간까지 전송된 데이터의 평균 전송률로 결정된다. Where

Is a time period in which the average data rate of the data is considered,

Denotes the transmission rate of data actually transmitted during that period. Therefore, the priority function is determined as the average transfer rate of data transmitted up to the last time period compared to the data transfer rate supported at the next time for the kth active user.

In this way, the PF scheduling method can ensure the proper priority according to the wireless environment and the amount of data to be transmitted can be equally transmitted to all active users.

은 이전(previous) 시구간의 무선채널정보를 기반으로 한다. 따라서, 채널의 변화가 심한 환경에서는 성능이 열화되는 문제점이 있었다. However, as shown in Equation (3) above,

Is based on the radio channel information of the previous time period. Therefore, there is a problem in that performance deteriorates in an environment in which channel changes are severe.

를

번째 시구간에 수신된 신호의 전력이라 하면,

시구간에서는 할당된 무선 자원에 비해 무선 채널의 변화에 따른 실제 전송 가능한 데이터 전송률은 낮아지게 되어 결과적으로 데이터 전송 오율(PER)이 증가하게 되며,

시구간에서는 할당된 무선 자원에 비해 무선 채널의 변화에 따른 실제 전송 가능한 데이터 전송률은 높아지게 되어 무선 자원 할당이 비효율적으로 이루어진 결과를 가져온다.That is, as shown in FIG.

To

If the power of the signal received in the first time period,

In the time period, the actual transmittable data rate due to the change of the wireless channel is lower than the allocated radio resource, resulting in an increase in the data transmission error rate (PER).

In the time period, the actual data rate that can be transmitted according to the change of the radio channel is higher than the allocated radio resource, resulting in inefficient radio resource allocation.

In addition, there is a problem in that it is not suitable to use the PF scheduling method in an environment in which the target data rate for each user such as xDSL service of wired communication is different. That is, in the wireless communication, the reserved bandwidth for each service class has a large difference in the packet transmission rate (PER) according to the wireless channel environment, and thus, the difference in the amount of data to be transmitted is also large. There was a problem that could not be a resource utilization method.

The present invention has been drawn to solve the above problems, an object of the present invention to provide a data transmission scheduling apparatus and method that simultaneously considers the service level and the wireless channel environment for each subscriber in a wireless communication environment.

In order to achieve the above object, a data transmission scheduling apparatus in a communication system according to the present invention includes a Proportional Fairness (PF) scheduler, which is a priority adjustment variable according to a service grade assigned to a terminal in a wireless communication system. Characterized in that.

In addition, the apparatus for scheduling data transmission in a communication system according to the present invention is characterized in that, in the wireless communication system, a PF (Proportional Fairness) scheduler which uses the variable of the received power of the terminal as a priority adjustment variable.

In addition, the apparatus for scheduling data transmission in the communication system according to the present invention uses the variable according to the service class assigned to the terminal as the first priority adjustment variable and the change in the received power of the terminal as the second priority adjustment variable. It characterized in that it comprises a PF (Proportional Fairness) scheduler.

Meanwhile, in the data transmission scheduling method in the communication system according to the present invention, in the method of scheduling data transmission from the communication system to the terminal, priority is set through PF (Proportional Fairness) scheduling, and priority is given to the set priority. Resetting the final priority considering the adjustment variable; And allocating data according to the reset priority.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments. Like reference numerals designate like elements throughout the drawings.

(First embodiment)

The service level for the target data rate for each user may select one rate from a data rate set. That is, if the service class assigned to each user is divided into three classes such as 1 class, 2 class and 3 class, and the corresponding data rates are 10Mbps, 5Mbps, and 1Mbps, respectively, the data rate set is 10Mbps, 5Mbps, 1Mbps. do.

However, as described in the related art, reserving bandwidth for each service class in wireless communication is not an efficient method for utilizing radio resources since it varies depending on a packet error rate (PER) according to a wireless channel environment.

Therefore, it is necessary to be able to maintain a higher priority than a low level service user while allocating radio resources dynamically according to a wireless channel environment for differentiated services by grade.

For this purpose, certain priority adjustment variables are considered. Representative of the above variables, the priority can be adjusted by using the data amount targeted by one user among the required data amounts of all users.

의 활성 사용자에 대해서

번째 시구간에서 전체 요구 전송률 중,

번째 활성 사용자의 목표 데이터 전송률의 비율을

이라 하면,

는 다음 수학식(4)와 같이 표현된다. Ie total

For active users in

Of the total required data rate in the first time period,

Of the target data transfer rate of the first active user

Speaking of

Is expressed by the following equation (4).

When the equation (4) is applied to the conventional PF scheduling method (that is, equation (1)), it can be expressed as the following equation (5).

By doing so, it is possible to transmit a certain level of data with fairness to users with low service grade while giving high priority to users with high service grade.

 Second Embodiment

을 정의할 수 있다. 이와 같이 정의함으로써, 종래기술에서 기재된 바와 같은 무선채널의 변화가 심한 환경에서도 PF스케줄링 방법에 따른 기지국에서 단말기로의 데이터전송 성능이 열화되는 문제점을 해결할 수 있다. Meanwhile, the received power change variable as shown in Equation (6) below.

Can be defined. By defining as described above, a problem of deterioration of data transmission performance from a base station to a terminal according to the PF scheduling method can be solved even in an environment in which the radio channel changes as described in the related art.

는 n번째 시구간에 수신된 신호의 전력을 나타내고,

는 n-1번째 시구간에 수신된 신호의 전력을 나타낸다.here,

Represents the power of the received signal in the nth time interval,

Denotes the power of the signal received in the n-th time period.

When the equation (6) is applied to the conventional PF scheduling method (that is, equation (1)), it can be expressed as the following equation (7).

By doing so, it is possible to prevent the efficiency degradation of the PF scheduling method due to the change in the radio channel environment.

(Third Embodiment)

Considering the equation (5) of the first embodiment and the equation (6) of the second embodiment at the same time, a certain level of data transmission was possible by assigning weights according to the service grade, and at the same time, the reception power at the terminal. By adding one more variable related to, it is possible to overcome the conditions caused by changes in the wireless channel environment.

In other words, as shown in FIG. 2, the priority adjustment variable as described above has a value greater than 1 when the received power continues to increase, and less than 1 when the received power continues to decrease. It may include conditions due to changes in the wireless channel environment.

(Example 4)

은 다음 수학식(8)과 같이 정의할 수 있 다. Meanwhile, the received power change variable

Can be defined as Equation (8) below.

은 구현 복잡도는 낮으나, 도2에 도시한 바와 같이, 지수함수(Exponential Function)형태의 증가함수이기 때문에, 무선 채널 환경이 개선될수록 필요이상의 큰 우선 순위를 갖게 되는 단점을 지닌다. Systemically, the equation (6)

Although the implementation complexity is low, as shown in Fig. 2, since it is an incremental function in the form of an exponential function, the radio channel environment has a disadvantage of having a greater priority than necessary.

However, as shown in Fig. 3, the priority adjustment variable as shown in Equation (8) has a value greater than 1 when the reception power continues to increase and less than 1 when the reception power continues to decrease. Therefore, it includes the conditions according to the change of the wireless channel environment.

In addition, as a symmetric function, there is an advantage of fairly reflecting the environmental change of the wireless channel.

과 무선채널 변화변수

를 고려한 우선 순위 함수

은 다음 수학식(9)과 같다.Class of Service variable above

And radio channel change variables

Priority function

Is as shown in Equation (9).

A system model for applying Equation (9) is shown in FIG.

4 is a schematic diagram illustrating a scheduler according to the present invention.

번째 활성 사용자의 목표 데이터 전송률을 입력 받아 총

의 활성 사용자에 대해서

번째 시구간에서 전체 요구 전송률 중

번째 활성 사용자의 목표 데이터 전송률의 비율을 계산하는 제1연산부(410)와, n번째 시구간에 수신된 신호의 전력(

)을 입력 받아 무선 채널 변화 변수

를 계산하는 제2연산부(420)와, 이전(previous) 시구간에 수신된 신호의 전력(

)를 저장하여 상기 제2연산부(420)에 피드백하는 메모리(430)와, 상기 제1연산부 (410) 및 제2연산부(420)의 계산 결과값을 입력 받아 데이터 전송순위를 결정하는 순위 결정부(440)를 포함한다. The scheduler 400,

The target data transfer rate of the first active user

For active users in

Of the total required transfer rate in the first time period

A first operation unit 410 for calculating a ratio of the target data rate of the first active user, and the power of the signal received in the nth time period (

Wireless channel change variable to take input

The power of the signal received in the second operation unit 420 and the previous time period (

) Is stored in the memory 430 to feed back to the second operation unit 420, the ranking determiner for receiving the calculation result value of the first operation unit 410 and the second operation unit 420 to determine the data transmission rank 440.

The scheduler 400 uses priority adjustment variables (service class variables, received power change variables) such as Equation (4), (6), or (8) through the configuration as described above. Finally, the priority of resource allocation in the wireless communication system is finally determined. For example, data transmission from the base station to the terminal may also be performed according to the priority determined by the scheduler 400.

While the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will recognize that various modifications or changes can be made without departing from the spirit and scope of the invention.

As described above, according to the present invention, there is an effect that can efficiently transmit data even with a sudden change in the wireless channel environment while meeting the service level required for each user, such as xDSL of wired communication.

Claims (16)

In a wireless communication system, It includes a PF (Proportional Fairness) scheduler to set the priority adjustment variable based on the variable according to the service class assigned to the terminal and the amount of data required by one terminal compared to the required data amount of the entire terminal to schedule data transmission. And a data transmission scheduling apparatus in a communication system. delete In a wireless communication system, And a Proportional Fairness (PF) scheduler whose priority adjustment variable is a change trend for a wireless channel environment set based on a received power change variable of the terminal. The method of claim 3, wherein the priority adjustment variable And a value greater than 1 if the reception power of the terminal continues to increase and less than 1 if the reception power continues to decrease. The method of claim 3, wherein the received power change variable

Say,

And a data transmission scheduling apparatus in a communication system. here,

Represents the power of the received signal in the nth time interval,

Denotes the power of the signal received in the n-th time period. The method of claim 3, wherein the received power change variable

Say,

And a data transmission scheduling apparatus in a communication system. here,

Represents the power of the received signal in the nth time interval,

Denotes the power of the signal received in the n-th time period. In a wireless communication system, A first priority adjustment variable is set based on a variable according to a service class assigned to a terminal and a variable according to the amount of data that a single terminal targets to the required amount of data of the entire terminal, and based on the variable of the received power of the terminal And a Proportional Fairness (PF) scheduler for setting a change trend for the wireless channel environment set as a second priority adjustment variable. delete 8. The method of claim 7, wherein the second priority adjustment variable is And a value greater than 1 if the reception power of the terminal continues to increase and less than 1 if the reception power continues to decrease. The method of claim 7, wherein the received power change variable

Say,

And a data transmission scheduling apparatus in a communication system. here,

Represents the power of the received signal in the nth time interval,

Denotes the power of the signal received in the n-th time period. The method of claim 7, wherein the received power change variable

Say,

And a data transmission scheduling apparatus in a communication system. here,

Represents the power of the received signal in the nth time interval,

Denotes the power of the signal received in the n-th time period. In the communication system scheduling method for transmitting data to each terminal, (a) Priority is set through PF (Proportional Fairness) scheduling, and the amount of data targeted by one terminal to the required data amount of the entire terminal and the variable according to the service class assigned to each terminal with respect to the set priority Resetting the final priority by using the priority adjustment variable based on the variable according to; And (b) allocating data according to the priorities reset in step (a). delete delete The method of claim 12, wherein step (a) The first priority adjustment variable is set based on the variable according to the service class assigned to each terminal and the variable according to the data amount of one terminal to the required data amount of all terminals, and the change in the received power of each terminal is adjusted. And setting the change trend for the wireless channel environment set based on the second priority adjustment variable as a second priority adjustment variable. The method of claim 15, wherein the second priority adjustment variable And a value greater than 1 if the reception power of the terminal continues to increase, and a value less than 1 if the reception power continues to decrease.

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