KR101241909B1 - Method For Modified Fractional Power Control - Google Patents

Abstract

An improved partial power control method and reference signal channel power control method are disclosed. Specifically, by defining one or more system parameters as a function of the difference value between the path loss with the serving cell and the path loss with the neighboring cell, and performing partial power control (FPC) through this, more interference with the neighboring cell can be seen. It can be controlled efficiently. In addition, by adjusting the difference between the transmission power of the data channel and the transmission power of the reference signal channel according to the received SIR value of the data channel for each UE, unnecessary interference between reference signals transmitted from the plurality of UEs can be prevented.

FPC, reference signal channel

Description

Improved Partial Power Control Method {Method For Modified Fractional Power Control}

1 is a diagram illustrating a change in transmission power and SIR_RX according to a change of a compensation coefficient value in an FPC scheme.

2 is a diagram for explaining a method of adjusting and applying a compensation coefficient according to a path loss difference according to one embodiment of the present invention;

3 and 4 are diagrams for explaining a method of adjusting and applying a target SIR and a target gain value according to a path loss difference according to another embodiment of the present invention, and FIG. 5 is yet another embodiment of the present invention. A diagram illustrating a method of adjusting and applying a compensation coefficient, a target SIR, and a target gain value all according to a path loss difference according to the present invention.

6 is a flow chart illustrating a method of applying an improved FPC in accordance with an embodiment of the present invention.

7 is a flowchart illustrating a method of controlling power of a reference signal channel by determining whether a TPR is changed by a UE according to an embodiment of the present invention.

8 and 9 illustrate examples of specific timings according to a TPR adjustment procedure when the UE determines whether a TPR is changed and controls power of a reference signal channel according to an embodiment of the present invention.

10 is a flowchart illustrating a method of controlling power of a reference signal channel by determining whether a TPR is changed by a base station according to another embodiment of the present invention.

11 and 12 are diagrams for explaining examples of specific timings according to a TPR adjustment procedure when the base station determines whether to change a TPR and controls power of a reference signal channel.

The following description relates to an improved partial power control method and reference signal channel power control method.

To this end, we first look at the open-loop power control method and power control method of the reference signal commonly used in mobile communication systems.

In a conventional mobile communication system, a service such as voice communication requires all users to have a constant data rate, and the required received signal-to-interference noise ratio (hereinafter referred to as "SIR") is the same. In a system requiring such a service, transmission power can be set as follows. In this case, the transmission power is always expressed as power in the case of a system using the same frequency band, and may be expressed as power per unit frequency or power per unit resource when the use frequency band is variable for each user's time. (Hereinafter, "power" means power per unit frequency or unit resource when the transmission frequency band is variable.)

를 나타낸다.Here, Equation 2 is an equation expressed in Equation 1 in dB unit,

Indicates.

는 기지국에서 수신되는 간섭과 AWGN 잡음의 합에 대한 단위자원당 수신전력(또는, PSD)이며,

은 서비스가 요구하는 SIR값이다. 이와 같은

과

는 시스템 파라미터로서 기지국에서 주어지는 값이다.Also, in the above equations

Is the received power per unit resource (or PSD) for the sum of interference and AWGN noise received from the base station,

Is the SIR value required by the service. Like this

and

Is a value given at the base station as a system parameter.

는 사용자 기기(UE)가 측정한 기지국과 UE간 채널의 평균 이득 값을,

는 UE의 단위자원당 최대전송 전력을 의미한다. 여기에서

는 단위주파수 혹은 단위자원당 송신전력을 의미하므로, 할당되는 자원의 양에 따라서 변할 수 있다.In addition, in the above equations

The average gain value of the channel between the base station and the UE measured by the user equipment (UE),

Means maximum transmission power per unit resource of the UE. From here

Since the transmission frequency per unit frequency or unit resource, it may vary depending on the amount of resources allocated.

과 동일한 값을 갖게 된다.At this time, if the SIR received from the base station is defined as SIR_RX, the average SIR_RX is the error in the measurement or transmission stage in the terminal

Will have the same value as

However, in a system for transmitting high-speed packet data such as a 3GPP LTE system, a data rate may be variably changed to be adaptive to a channel state in order to maximize frequency efficiency. To do this, the UE at the center of the cell sets the transmit power to have a high receive SIR, and the UE located at the edge of the cell sets the transmit power to be received at a low receive SIR for lower data interference and lower interference to adjacent cells. do. One of the proposed methods for this is the Fractional Power Control (“FPC”) method.

In the FPC scheme as described above, UEs having the same path-loss, that is, the same channel gain, as the serving base station transmit data at the same transmission power. However, although the UE at the cell edge statistically significantly interferes with the neighboring cell, the factor that has a greater influence on the interference is the path loss with the neighboring base station.

As such, these parts are not reflected in the conventional FPC, so that when the UE having a large interference with the neighboring base station and the UE having a small interference have the same path loss as the serving base station, efficient interference control is performed by transmitting data at the same transmission power. There is a drawback to not doing it.

Meanwhile, a method of controlling the transmission power of a reference signal in relation to the data transmission power control described above will be described below.

For example, the uplink data channel is not transmitted continuously or periodically, but only when the base station allocates resources to each UE. In addition, in a packet communication system such as a 3GPP LTE system, frequency selective fast scheduling is performed for efficient use of frequency resources, and for this purpose, the UE periodically transmits a reference channel. A channel usable as such a reference channel generally has a periodic transmission characteristic. In the 3GPP LTE system, a representative channel includes an uplink CQICH or a sounding channel (CQ pilot). There is this.

In this case, since a plurality of UEs need to transmit a reference channel, reference signals of the plurality of UEs must be multiplexed over the entire system frequency band. Therefore, if the transmission power of the reference channel becomes too large, it causes a lot of interference in the system, and therefore it is advantageous to transmit with the minimum power to reliably measure the channel condition. To this end, a method of transmitting a reference signal while maintaining a constant difference with the transmission power per unit frequency determined for data transmission is currently being discussed. Through this, the base station can not only support efficient scheduling of the data channel from the reception quality measurement of the reference channel but also perform efficient interference control.

However, when the reception power is different according to the environment of the channel as in the above-described FPC scheme, the transmission power of the reference channel is different for each UE, and particularly in the case of a UE transmitting with a large power, the same channel is used when the reference channel is used as well as the neighboring base station. There is a problem in that reference channels of UEs in a cell may act as large interference with each other.

SUMMARY OF THE INVENTION In order to solve the problems as described above, an object of the present invention is to propose an improved FPC method for more efficiently reducing the influence of neighboring cell interference in the FPC method proposed as a method of open loop power control.

In addition, the present invention provides a method of more efficiently setting the transmission power of the reference signal channel based on the data channel power control method or the existing data channel power control method.

A partial power control method as an embodiment according to an aspect of the present invention for achieving the above object is a method of performing partial power control (FPC) according to one or more system parameters, the path with the service cell Calculating a difference value between a loss and a path loss between neighboring cells, determining at least one of the one or more system parameters according to the difference value, and determining a transmit power according to the determined one or more system parameters It includes.

In addition, the partial power control method according to another embodiment of the present invention, a method for performing partial power control according to one or more system parameters, any one or more of the one or more system parameters, and Defining in the form of a function of the difference value of the path loss with a neighboring cell, and transmitting the one or more system parameters to each user device including the parameter defined in the form of the function of the difference value.

In this case, the one or more system parameters may be parameters for power control, and specifically, may include one or more of a target signal-to-interference ratio, an interference power value, a target gain value, and a compensation factor. In addition, parameters defined as a function of the difference value may be set to different values depending on whether the difference value is greater than or equal to a predetermined threshold.

On the other hand, the power control method of the reference signal channel according to another aspect of the present invention for achieving the above object, by setting the transmission power of the reference signal channel to have a predetermined difference value with the transmission power of the data channel Transmitting a reference signal, and performing a process for adjusting the difference value when the received signal-to-noise ratio predicted according to the transmission power of the data channel is changed based on a predetermined threshold value.

In this case, the process for adjusting the difference value, reporting the adjustment information of the difference value to the base station, and after a predetermined time after the report the reference signal transmission power is the transmission power of the data channel and the adjusted difference value The reference signal may be transmitted by setting to have a difference, and the process for adjusting the difference value may include reporting to the base station that the difference value needs to be adjusted, and the difference value adjusted from the base station. Receiving the information, and setting the reference signal transmission power to have the adjusted difference value with the transmission power of the data channel after a predetermined time after the reception, and transmitting the reference signal.

In addition, the power control method of the reference signal channel according to another embodiment of the present invention, the step of predicting the received signal-to-noise ratio of the data channel through a received signal from one or more user equipment, and the predicted received signal-to-noise ratio is predetermined If the threshold value is changed based on the threshold value, performing a process for adjusting the difference value.

In this case, the received signal from the one or more user equipments may include information on any one or more values of a path loss with a service cell and a difference between a path loss with the service cell and a path loss with a neighbor cell. Alternatively, the received signal from the one or more user equipments may include any one or more of data and reference signals.

The processing for adjusting the difference value may include transmitting the difference value adjustment information to the one or more user equipments, and a received signal-to-power ratio of a reference signal received from the one or more user equipments after a predetermined time after the transmission. The method may include applying the adjusted difference value in the process of estimating the received signal-to-power ratio of the data channel.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details.

On the other hand, in some cases, well-known structures and devices are omitted in order to avoid obscuring the concepts of the present invention, or shown in block diagram form centering on the core functions of each structure and device. In addition, the same components will be described with the same reference numerals throughout the present specification.

As described above, one aspect of the present invention is to provide an FPC method for efficiently reducing the influence of neighboring cell interference. To this end, the system parameters used in the conventional FPC scheme will be described in more detail, and these parameters are efficiently set according to the difference between the path loss value of the serving cell and the path loss value of the neighboring cell. We look at how to implement an improved FPC in accordance with one aspect.

는 다음과 같이 표현될 수 있다.As described above, the FPC scheme sets the transmission power so that the UE at the center of the cell has a high reception SIR, and the UE located at the edge of the cell has a low reception SIR to reduce interference to neighboring cells and perform stable data transmission. A method of setting the transmission power to be received, the transmission power of the data channel in this FPC method

Can be expressed as follows.

Here, Equation 4 is an equation expressed in Equation 3 in dB unit, wherein

,

,

.

(간섭 전력 값)는 기지국에서 수신되는 간섭과 AWGN 잡음의 합에 대한 단위자원당 수신전력(또는, PSD),

(목표 신호대간섭잡음비)은 채널의 이득 값이

(목표 이득 값)일 때 기지국에서 수신될 것으로 예측되는 SIR값,

(평균 이득값)는 UE가 측정한 기지국과 UE간 채널의 평균 이득 값,

는 UE의 단위 주파수 혹은 자원당 최대 송신 전력을 의미한다. 또한,

(alpa)는 "보상 계수(compensation factor)"로서,

=1인 경우 일반적인 개루프 전력 제어로 동작하게 되어 셀 내의 모든 UE는 평균 SIR_RX가 모두 동일하게 수신되며,

< 1인 경우 UE의 위치에 따라 평균 SIR_RX을 조절하는 인자로 작용한다. Also, in the above equations

(Interference power value) is received power per unit resource (or PSD) for the sum of interference and AWGN noise received from the base station,

(Target signal-to-interference noise ratio) is the gain value of the channel

SIR value expected to be received at the base station when (target gain value),

(Average gain) is the average gain of the channel between the base station and the UE as measured by the UE,

Means the maximum transmission power per unit frequency or resource of the UE. Also,

(alpa) is the "compensation factor"

If = 1, then it will operate under normal open-loop power control so that all UEs in a cell receive the same average SIR_RX.

If <1, it serves as a factor for adjusting the average SIR_RX according to the position of the UE.

,

,

,

는 시스템 파라미터로서 기지국이 각 UE에게 알려주는 값이다.In the above equations

,

,

,

Is a value that the base station informs each UE as a system parameter.

FIG. 1 is a diagram illustrating a change in transmission power and SIR_RX according to a change in a compensation coefficient value in the FPC method.

값을 설정하게 된다. 일반적으로 이와 같은 동작을 위해서는

< 1을 만족해야 한다.As can be seen from Figure 1, in the FPC, the signal of the UE at the cell edge can act as a large number of interference signals to the neighboring cells, thereby assigning transmission power to be received at a low SIR, and the signal of the cell-centric UE is Since only a small part of the adjacent cell acts as an interference signal, it can be received higher than the target SIR toward the cell center.

Set the value. In general, this behavior

<1 must be satisfied.

In such FPC, UEs having the same path loss (ie, channel gain) as the serving base station transmit data at the same power. However, although the UE at the cell boundary statistically significantly interferes with the neighboring cell, the factor that has a greater influence on the interference is the path loss with the neighboring base station as described above. Accordingly, in one aspect of the present invention, in applying the FPC, one or more system parameters used in Equations 3 and 4 are differently applied depending on the difference between the path loss with the serving cell and the path loss with the neighbor cell. Therefore, it is proposed to perform power control in consideration of the degree of interference to the actual neighboring cell even though the same path loss as that of the serving cell.

According to an aspect of the present invention, such an improved FPC scheme may be represented as follows.

Here, Equation 6 represents Equation 5 in dB units,

to be.

)는 다음과 같이 규정될 수 있다.As can be seen from Equations 5 and 6, in an embodiment according to an aspect of the present invention, a difference between a path loss with a serving cell and a path loss with an adjacent cell ("path loss difference" for convenience of description). In order to adjust the influence of interference on the neighboring cell, various factors (ie, system parameters) that can be controlled by the base station are defined and transmitted to each UE as a function of a path loss difference. Thus, the path loss difference for adjusting the predetermined system parameter (

) Can be defined as follows.

,

,

등이 있을 수 있으며, 본 발명의 각 실시형태에서 필요에 따라 이들의 임의의 조합을 이용할 수 있다. Here, PL _SC denotes a path loss with a serving cell, and PL _NC denotes a path loss with an adjacent cell. The system parameters that can be adjusted according to these path loss differences are

,

,

Etc., and any combination of these may be used as needed in each embodiment of the present invention.

를 경로 손실차에 따라 조절하는 경우를 살펴본다.Hereinafter, as an embodiment of the present invention described above

Look at the case of adjusting according to the path loss difference.

2 is a diagram for describing a method of adjusting and applying a compensation coefficient according to a path loss difference according to an embodiment of the present invention.

를 모든 UE에게 동일하게 적용하지 않으며, 기지국은

값을 상술한 경로 손실 차의 함수 형태로 각 UE에게 알려 줄 수 있다. 이러한 경우 UE는 서비스 셀과 이웃 셀의 경로 손실을 측정하고, 경로 손실차가 기지국이 정해준 임계치(T)보다 큰 UE에게는

를 작은 값으로 설정하여 송신 전력을 결정하고, 경로 손실 차가 기지국이 정한 임계치보다 작은 UE는

를 큰 값을 사용하여 송신 전력을 결정하여 송신하게 된다. In this embodiment shown in FIG. 2

Does not apply equally to all UEs,

The value may be informed to each UE as a function of the path loss difference described above. In this case, the UE measures the path loss of the serving cell and the neighbor cell, and for the UE whose path loss difference is larger than the threshold value T defined by the base station.

Is set to a small value to determine the transmit power, and the UE whose path loss difference is smaller than the threshold determined by the base station

The transmission power is determined by using a large value.

Specifically, when the FPC is improved as shown in FIG. 2, in the case of a UE whose path loss difference is greater than or equal to the threshold value T defined by the base station, as the path loss with the serving cell increases, the UE has a small reception SIR and a path with the serving cell. While the transmission power is set to have a large reception SIR as the loss becomes smaller, the transmission power can be set to have the same reception SIR regardless of the path loss with the serving cell in case of a UE whose path loss difference is smaller than the aforementioned threshold. .

이외에 다른 시스템 파 라미터를 경로 손실 차의 함수 형태로 규정하여 FPC를 적용할 수 있다.In another embodiment of the present invention,

In addition, FPC can be applied by defining other system parameters as a function of the path loss difference.

), 목표 이득 값(

)을 경로 손실 차에 따라 조정하여 적용하는 방식을 설명하기 위한 도면이며, 도 5는 본 발명의 또 다른 일 실시형태에 따라 보상 계수(

), 목표 SIR(

), 및 목표 이득 값(

)을 모두 경로 손실 차에 따라 조정하여 적용하는 방식을 설명하기 위한 도면이다.3 and 4 illustrate a target SIR (in accordance with another embodiment of the present invention);

), The target gain value (

) Is a view for explaining a method of adjusting and applying according to the path loss difference, Figure 5 is a compensation coefficient (in accordance with another embodiment of the present invention)

), Target SIR (

), And the target gain value (

) Are diagrams for explaining a method of adjusting and applying all of them according to the path loss difference.

(delta))에 따라 목표 이득값(

)을 조정하는 본 실시형태에 있어서, 경로 손실 차가 기지국이 설정한 소정 임계치(T)보다 큰 경우, 서비스 셀과 동일한 경로 손실을 가지는 UE들 간에도 보다 낮은 송신 전력을 통해 높은 수신 SIR을 가지도록 송신할 수 있음을 알 수 있다. 또한, 도 4에 도시된 바와 같이 경로 손실차에 따라 목표 SIR값을 조정하는 본 실시형태에 있어서, 경로 손실 차가 기지국이 설정한 임계치보다 큰 경우, 서비스 셀과의 동일한 경로 손실을 가지는 UE들 간에도 보다 높은 송신 전력으로 보다 높은 수신 SIR을 가지도록 송신할 수 있음을 알 수 있다.Specifically, as shown in FIG. 3, the path loss difference (

(delta))

In the present embodiment of the present invention, when the path loss difference is larger than a predetermined threshold T set by the base station, transmission between the UEs having the same path loss as the serving cell has a high reception SIR through lower transmission power. It can be seen that. In addition, in the present embodiment in which the target SIR value is adjusted according to the path loss difference as shown in FIG. 4, when the path loss difference is larger than the threshold set by the base station, even among UEs having the same path loss with the serving cell. It can be seen that it is possible to transmit to have a higher received SIR with a higher transmit power.

In addition, when all of the above-described compensation coefficient, target gain value, and target SIR value are adjusted according to the path loss difference, as shown in FIG. 5, the effects in the above-described embodiments are compounded in the same manner. Through this, it is possible to more effectively control the influence of interference on the adjacent cell.

Meanwhile, in the above-described embodiments, the compensation coefficient, the target gain value, the target SIR value, and the like are divided into two stages according to whether the path loss difference is greater than or equal to the threshold value, but adjusting each system parameter is performed using a plurality of threshold values. It may be adjusted to a plurality of levels, and may preferably be defined in the form of a continuous function depending on the path loss difference.

The improved FPC scheme according to each embodiment of the present invention as described above is summarized as follows.

6 is a flowchart illustrating a method of applying an improved FPC in accordance with an embodiment of the present invention.

), 목표 SIR(

), 및 목표 이득값(

) 등의 시스템 파라미터 중 어느 하나 이상의 시스템 파라미터를 경로 손실 차의 함수 형태로 규정한다. 즉, 도 2에 도시된 실시형태에서는 보상 계수만을, 도 3에 도시된 실시형태에서는 목표 SIR값을, 도 4에 도시된 실시형태에서는 목표 이득값을, 도 5에 도시된 실시형태에서는 이들 3가지 시스템 파라미터 모두를 경로 손실 차의 함수 형태로 규정하는 것을 예시하고 있으나, 본 발명은 이들 실시형태들에 한정될 필요는 없으며 임의의 하나 이상의 시스템 파라미터가 경로 손실차의 함수 형태로 규정될 수 있다. 그 후, 단계 S602에서 기지국은 단계 S601에서 규정된 시스템 파라미터들에 대한 정보를 각 UE에 송신한다.That is, according to the present embodiment, first, in step S601, the base station determines a compensation coefficient (

), Target SIR (

), And the target gain value (

One or more of the system parameters, such as), are defined as a function of the path loss difference. That is, only the compensation coefficient in the embodiment shown in FIG. 2, the target SIR value in the embodiment shown in FIG. 3, the target gain value in the embodiment shown in FIG. 4, and these three in the embodiment shown in FIG. 5. Although all branch system parameters are defined as a function of the path loss difference, the present invention need not be limited to these embodiments and any one or more system parameters may be defined as a function of the path loss difference. . Then, in step S602, the base station transmits information about system parameters defined in step S601 to each UE.

The system parameter information transmitted as described above is received by each UE, and each UE determines transmission power through the following procedure.

First, in step S603, the aforementioned path loss difference is calculated. That is, the difference between the path loss with the serving cell and the path loss with the neighboring cell is calculated, where the path loss value with the neighboring cell has the greatest effect among the neighboring cells, for example, the path loss with the nearest cell. It is preferable to use.

Thereafter, in step S604, system parameters used for the FPC are determined according to the path loss difference calculated in step S603. That is, one or more parameters of the system parameters used in the FPC are defined as a function of the path loss difference described above, and in step S604, these system parameters may be determined using the path loss difference value calculated by step S603. Meanwhile, other system parameters not defined as a function of the path loss difference may be determined at the time of reception from the base station.

As such, when system parameters used for the FPC are determined, in step S605, each UE may determine transmission power by the FPC.

According to the embodiment of the present invention as shown in FIG. 6, it is possible to improve the system performance in consideration of the effect on the adjacent cells in setting the transmission power of the data transmission channel. Hereinafter, as another aspect of the present invention, when the transmission power of the data channel is determined based on the improved FPC scheme as described above or based on the existing FPC scheme, a method of setting the transmission power of the reference signal channel Explain about.

As described above, reference signals of a plurality of UEs must be multiplexed throughout the system frequency band in the reference channel. Therefore, if the transmission power of the reference channel becomes too large, it causes a lot of interference in the system, and therefore it is advantageous to transmit with the minimum power to reliably measure the channel condition. To this end, a method of transmitting a reference signal while maintaining a constant difference (hereinafter, referred to as "TPR") from the transmission power per unit frequency determined for data transmission has been discussed. Through this, the base station can not only support efficient scheduling of the data channel from the reception quality measurement of the reference channel but also perform efficient interference control.

However, when the reception power is different according to the environment of the channel, such as the above-described FPC scheme (or the improved FPC scheme according to an aspect of the present invention as described above), the transmit power of the reference channel is different for each UE, and especially a large power In the case of a UE to be transmitted, there is a problem in that the reference channels of the UE as well as the neighboring base station can act as a large interference between the reference channels of the UE in the same cell.

Accordingly, the control channel transmission power setting method according to an aspect of the present invention proposes a method of changing and transmitting the above-described TPR (that is, a difference between the transmission power of the reference channel and the data channel) according to the reception power level of the data channel.

In this case, whether or not the TPR is changed and the changed TPR should be known in common between the UE and the base station. For this purpose, a person who is in charge of the TPR change and methods for reporting and applying to the other party should be defined. Ways to implement this may exist in a variety of forms, and will be described below through various embodiments of the present invention.

First, when the UE determines and applies the TPR change described above, and the base station determines and applies the TPR change as follows.

FIG. 7 is a flowchart illustrating a method of controlling a power of a reference signal channel by determining whether a TPR is changed according to an embodiment of the present invention.

In this embodiment illustrated in FIG. 7, first, in step S701, each UE transmits a reference signal channel by setting power of each channel such that the data channel and the reference signal channel have a preset TPR. Meanwhile, in step S702, the UE continuously examines whether the received SIR of the data channel predicted according to the transmission power of the data channel set through step S701 is changed based on a predetermined threshold. (Or, since the reference channel is set to have a preset TPR with the data channel, the received SIR of the reference channel can also be used for the same purpose.) If the received SIR of the data channel predicted as a result of step S702 is less than or equal to the above-described threshold, If changed above the threshold value described above, the UE may perform a procedure for increasing the TPR according to step S703. On the other hand, if the received SIR of the data channel predicted as a result of step S702 is changed from above the above threshold to below the above threshold, the UE may perform a procedure for reducing the TPR according to step S704.

At this time, the procedure for increasing or decreasing the TPR (that is, the procedure for adjusting the TPR) may also be various ways, for example, after adjusting the TPR value directly at each UE and transmitting the adjusted TPR information to the base station. After a predetermined time has elapsed, the adjusted TPR value may be applied to transmit the reference signal channel. In contrast, each UE informs the base station that the TPR value needs to be adjusted, and the base station that has received the report indicates whether the TPR is adjusted. And transmit power of the reference signal channel after a predetermined time has elapsed.

Hereinafter, a method of controlling power of a reference signal channel according to embodiments as described above will be described in detail with respect to timing at which each step is performed.

8 and 9 are diagrams for explaining examples of specific timings according to a TPR adjustment procedure when the UE determines whether to change a TPR and controls power of a reference signal channel.

Although the improved FPC scheme according to an aspect of the present invention described above may be used as the transmission power control method of the data channel, the conventional FPC as the transmission power control method of the data channel for convenience of description in FIGS. 8 and 9. It is assumed to use the method.

Specifically, referring to each graph in FIG. 8 and FIG. 9, "Pathloss" is a path loss value between the serving cell and the UE measured by the UE, and does not consider shadowing. FIGS. 8 and 9 9 indicates a state in which the UE approaches the base station. In addition, "P_DATA, TX" and "P_REF, TX" indicate the transmission power of the data channel and the reference signal channel, respectively, and "SIR_RX" indicates the reception SIR of the data channel received at the base station. Finally, "TPR" represents the transmission power ratio per unit frequency of the data channel and the reference signal channel as described above.

First, the operation of the base station and the UE at each timing will be described in detail with reference to FIG. 8.

T1 to T2: The UE always loses the path of the serving cell (if the data channel transmit power control scheme uses the improved FPC scheme according to the above-described aspect of the present invention, additionally the path between the serving cell and the strongest neighbor cell). The difference value of the loss) and measure the transmission power of the data channel accordingly. In this case, the TPR may be determined according to the predicted received SIR.

T2: The UE continuously sets the transmission power according to the measured path loss (or path loss difference), and looks at whether the predicted average received SIR exceeds a certain threshold (T). When it is detected that the average received SIR exceeds the threshold, it is prepared to report it to the base station.

T3: When a transmission resource is allocated from the base station, the UE reports to the base station through the higher signaling message about the adjustment information of the TPR value.

T4: From the time point at which the TPR change is reported to the base station (or the time point at which the base station notifies the UE that the above-described higher signaling message has been correctly received), the UE is changed to the transmit power of the reference signal channel after a predetermined time Tgap. By applying TPR, the base station applies the adjusted new TPR value in the process of predicting the received SIR of the data channel from the received SIR of the reference signal channel. In this case, the Tgap may be prevented from deterioration of performance by setting a time point at which the base station and the UE promise each other, but may be applied at different time points between the base station and the UE.

Meanwhile, FIG. 9 has a somewhat different feature in the process of FIG. 8 and the UE performing a procedure for TPR coordination. Hereinafter, operations of the base station and the UE at each timing will be described in detail with reference to FIG. 9.

T1 to T2: As in the case of FIG. 8, the UE always adds a path loss with the serving cell (if the data channel transmit power control scheme uses the improved FPC scheme according to the above-described aspect of the present invention). The difference in the path loss between the serving cell and the strongest neighbor cell) is measured, and the transmit power of the data channel is set accordingly. At this time, the TPR uses a value previously given by the base station.

T2: The UE continuously sets the transmission power according to the measured path loss (or path loss difference) and looks at whether the predicted average received SIR exceeds a certain threshold T. If it is detected that the average received SIR exceeds the thresholds described above, the UE prepares to report it to the base station.

T3: When a transmission resource is allocated from a base station, the UE reports to the base station that SIR_RX has exceeded the threshold, that is, TPR adjustment is needed, through an upper signaling message.

T4: After receiving the report from the UE, the base station instructs the UE to change the TPR value when it is determined to be necessary.

T5: After a predetermined time Tgap has elapsed at the time of instructing the TPR adjustment to the UE (or at the time of recognizing that the upper signaling message has been properly received), the UE adjusts the transmit power of the reference signal channel to the adjusted TPE value. The base station applies the adjusted new TPR value in the process of predicting the received SIR of the data channel from the received SIR of the reference signal channel. In this case, the Tgap can be prevented from deterioration by setting the time point as promised by the base station and the UE as described with reference to FIG. 8, but may be applied at different times by the base station and the UE.

In the following, an embodiment in which the base station determines whether or not the TPR value is changed in controlling the transmission power of the reference signal channel as described above will be described.

FIG. 10 is a flowchart illustrating a method of controlling power of a reference signal channel by determining whether a TPR is changed by a base station according to another embodiment of the present invention.

In the present embodiment shown as shown in FIG. 10, first, in step S1001, the base station receives a signal from each UE to predict a received SIR of the data channel. In this case, the received signal from the UE used for the received SIR prediction of the data channel may be a general data signal, or may be path loss information (or path loss difference information when using an improved FPC) measured with each serving cell. have. Specifically, when the received signal from the UE used for the received SIR prediction of the data channel is a general data signal, step S1001 may simply mean the SIR measurement step of the received data, and the UE used for the received SIR prediction of the data channel. If the received signal from the path loss information (or path loss difference information) with the service cell measured in the UE in step S1001 through this path loss information through the FPC (or improved FPC) scheme of the data channel Predicting the received SIR.

Thereafter, in step S1002, the base station examines whether or not the received SIR of the data channel predicted through step S1001 changes to a boundary of a predetermined threshold T. If it is detected that the received SIR predicted as a result of step S1002 changes from below the threshold to above the threshold, the base station may perform a procedure for increasing the TPR in step S1003. On the other hand, if it is detected that the received SIR predicted as a result of step S1002 changes from above the threshold to below the threshold, the base station may perform a procedure for reducing the TPR in step S1004.

Hereinafter, a method of controlling power of a reference signal channel according to the above-described embodiment will be described in detail with respect to timing at which each step is performed.

11 and 12 are diagrams for explaining examples of specific timings according to a TPR adjustment procedure according to an embodiment of the present invention in which a base station determines whether a TPR is changed to control power of a reference signal channel.

First, the operation of the base station and the UE at each timing will be described in detail with reference to FIG. 11.

T1 to T2: The UE always has a path loss value with the serving cell (if the data channel transmit power control scheme uses the improved FPC scheme according to the above-described aspect of the present invention, additionally with the serving cell and the strongest neighbor cell; The difference value of the path loss of the () is measured and reported to the base station periodically. At this time, the TPR uses a value previously given from the base station.

T2: If the base station determines that the TPR value should be adjusted from the path loss value (or path loss difference value) with the last reported serving cell, it commands each UE to change the TPR value through an upper signaling message.

T3: After a predetermined time (Tgap) has elapsed at the time of instructing the TPR change to the UE (or at the time of recognizing that the upper signaling message has been properly received), the UE adjusts the transmit power of the reference signal channel to the adjusted TPR value. And the base station applies the adjusted new TPR value in the process of predicting the received SIR of the data channel from the received SIR of the reference signal channel. In this case, the above-described predetermined time Tgap may be prevented from deterioration of performance by setting the time point that the base station and the UE promise to each other, but the base station and the UE may be applied at different time points.

Meanwhile, in the embodiment of the present invention shown in FIG. 12, the BS determines a TPR change by directly measuring a received SIR through a data signal received from the UE. This will be described in detail.

T1.x: The base station continuously measures the received SIR of the data channel and the reference signal channel transmitted by the UE.

T2: When the base station determines that the TPR value should be changed from the result of continuously measuring the received SIR of the data channel and the reference signal channel transmitted by the UE, the base station prepares to change the TPR.

T3: Notifies the UE to change the TPR value through an upper signaling message.

T4: After a predetermined time (Tgap) has elapsed at the time of instructing the TPR change to the UE (or at the time of recognizing that the upper signaling message has been properly received), the UE changes the transmit power of the reference signal channel to the changed TPR value. The base station applies the adjusted new TPR value in the process of predicting the received SIR of the data channel from the received SIR of the reference signal channel. In this case, the predetermined time Tgap may be prevented from deterioration of performance by setting the predetermined time Tgap to a point in time promised by the base station and the UE, but the base station and the UE may be applied at different points in time.

The detailed description of the preferred embodiments of the invention disclosed as described above is provided to enable any person skilled in the art to make and practice the invention. Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can. Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

According to one embodiment of the present invention as described above, it is possible to implement an improved FPC method that more efficiently reduces the effect of neighboring cell interference in the proposed FPC method as a method of open loop power control.

In addition, in both the case of applying the conventional FPC scheme to the power control scheme of the data channel and the case of applying the improved FPC scheme as described above, according to the transmission power of the data channel of each UE efficiently By setting the transmission power of the reference signal channel, it is possible to prevent unnecessary interference between reference signals of each UE in the cell as well as interference with adjacent cells.

Claims (12)

In the method of performing partial power control (FPC) in accordance with one or more system parameters, Calculating a difference value between a path loss with a serving cell and a path loss with a neighbor cell; Determining at least one of the one or more system parameters according to the difference value; And Determining transmission power in accordance with the determined one or more system parameters. In the method of performing partial power control (FPC) in accordance with one or more system parameters, Defining any one or more of the one or more system parameters as a function of a difference value between a path loss with a serving cell and a path loss with a neighbor cell; And Transmitting said one or more system parameters to each user equipment including parameters defined as a function of said difference value. 3. The method according to claim 1 or 2, Wherein said at least one system parameter is a parameter used for power control. The method of claim 3, wherein Wherein the one or more system parameters include any one or more of a target signal-to-interference ratio, an interference power value, a target gain value, and a compensation factor. 3. The method according to claim 1 or 2, The parameter defined as a function of the difference value is set to different values depending on whether the difference value is greater than or equal to a predetermined threshold. delete delete delete delete delete delete delete

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