KR100732058B1 - Method for transferring channel quality indicator in a terminal - Google Patents

Abstract

The present invention relates to a method for transmitting a channel quality indicator of a terminal, comprising: receiving a reference value for transmitting a channel quality indicator from a base station; Checking the forward channel state; Determining whether the variation value of the channel state satisfies a reference value; The channel quality indicator is transmitted when the variation value of the channel state does not satisfy the reference value, and the channel quality indicator is not transmitted when the variation value of the channel state satisfies the reference value.

Description

How to send a channel quality indicator on your device {METHOD FOR TRANSFERRING CHANNEL QUALITY INDICATOR IN A TERMINAL}

1 is a configuration diagram schematically showing the structure of a general WCDMA communication system.

2 illustrates a "Radio Bearer Setup" message according to the present invention.

3 illustrates a CQI transmission process in accordance with the present invention.

** Description of the symbols for the main parts of the drawings **

100: core network 110, 120: wireless network subsystem

111, 121: Wireless network controller 113, 115, 123, 125: Base station

130: user terminal

The present invention relates to a terminal supporting a high speed forward packet access (HSDPA) scheme, and more particularly, to a method for providing a channel quality indicator of an HSDPA terminal.

Today's mobile communication systems are evolving into high-speed, high-quality wireless data packet communication systems to provide data services and multimedia services. High speed downlink packet access (HSDPA) and 1xEV-DV standardization currently underway around 3GPP and 3GPP2 are standardized for high-speed, high-quality wireless data of more than 2 Mbps in 3G mobile systems. Efforts to find a solution for the packet transmission service can be seen as a typical example.

In general, HSDPA is a control channel associated with a forward data channel (HS-DSCH: High Speed-Downlink Shared Channel (HS-DSCH) hereinafter) for supporting forward high speed packet transmission in a W-CDMA communication system. And apparatus, systems, and methods therefor. In order to support the HSDPA, an adaptive modulation and coding (AMC) scheme has been proposed.

1 is a schematic diagram showing the structure of a typical W-CDMA communication system.

The W-CDMA communication system includes a core network (CN) 100, a plurality of radio network subsystems (RNS) (hereinafter, referred to as "RNS"), and a user terminal. (UE: User Equipment, hereinafter referred to as " UE ") 130.

The RNS 110 and the RNS 120 may be referred to as a Radio Network Controller (RNC: hereinafter referred to as "RNC") and a plurality of base stations (Node B) (Node B or cell in the following description). To use).

For example, the RNS 110 is composed of an RNC 111 and a plurality of Node Bs 113 and 115. The RNC is classified into Serving RNC (hereinafter referred to as "SRNC"), Drift RNC (hereinafter referred to as "DRNC"), or Controlling RNC (hereinafter referred to as "CRNC") according to its role. The SRNC and the DRNC are classified according to the role for each UE, and the RNC managing the information of the UE and in charge of data transmission with the core network becomes the SRNC of the UE, and the data of the UE is not the SRNC. When the RNC is transmitted and received through the SRNC, the RNC becomes the DRNC of the UE. The CRNC represents an RNC controlling each Node B.

For example, if the RNC 111 manages information of the UE 130, the RNC 111 becomes an SRNC, and the UE 130 moves to transmit data of the UE 130 to the RNC 121. When the transmission and reception through the RNC 121 becomes a DRNC. The RNC 111 controlling the Node B 113 becomes the CRNC of the Node B 113. The AMC scheme determines the modulation scheme and the coding scheme of different data channels according to the channel state between the Node B 123 and the UE 130 illustrated in FIG. That's the way. Accordingly, the AMC scheme has a plurality of modulation schemes and a plurality of coding schemes, and modulates and codes a data channel by combining the modulation schemes and the coding scheme. In general, each of the combinations of modulation schemes and coding schemes is called a modulation and coding scheme (MCS), and a plurality of combinations of the modulation schemes and coding schemes may be used. MCS levels can be defined.

In other words, the AMC scheme means a scheme for adaptively determining the level of the MCS according to the channel state between the UE 130 and the Node B 123 that is currently wirelessly connected to increase the overall system efficiency. The MCS level as described above is control information considered by the base station to support the HSDPA scheme. When the UE measures the current downlink channel condition and provides this result to the base station through a channel quality indicator (CQI), the MCS level is calculated by the base station. do.

Therefore, the UE repeats the process of receiving the forward channel signal, measuring the CQI for the received forward channel signal, and reporting the measured CQI to the base station at regular intervals. This periodic CQI reporting method is specifically performed between the UE and the base station through the following procedure.

(1) The terminal checks the forward channel state (transport block size, number of HS-PDSCH codes, modulation scheme).

(2) A CQI corresponding to a transport block size, the number of HS-PDSCH codes, and a modulation scheme is selected from a mapping table stored in the terminal. Here, the CQI should be selected in a range in which a bit error rate (BER) of the downlink does not exceed 0.1.

(3) The terminal transmits the selected CQI to the base station through the HS-DPCCH channel.

In general, the period in which the terminal transmits the CQI to the base station is selected from among 0, 1, 2, 4, 5, 10, 20, 40, and 80 subframes, and the shorter the transmission period, the higher the throughput, but the CQI overhead And uplink interference is increased.

In addition, the terminal using the above process periodically transmits the CQI even when there is no sudden change of the channel state, causing a problem of shortening the battery usage time by causing power consumption.

The present invention has been proposed to solve the above problems, and an object of the present invention is to reduce the battery consumption of the terminal by transmitting the CQI information to the base station only when the channel state variation exceeds the threshold. The present invention provides a method for transmitting a channel quality indicator of a terminal.

In order to achieve the above object, the channel quality indicator transmission method of the terminal according to the present invention comprises the steps of receiving a reference value for the channel quality indicator (Channel Quality Indicator) transmission from the base station; Checking the forward channel state; Determining whether the variation value of the channel state satisfies a reference value; And transmitting a channel quality indicator when the variation value of the channel state does not satisfy the reference value and not transmitting the channel quality indicator when the variation value of the channel state satisfies the reference value.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

)을 나타내는 수학식 1을 통해 예측해보기로 한다. First, the battery usage gain of the terminal (

Predicted by the equation (1).

는 데이터 전송을 통한 패킷 서비스 시간을,

는 CQI 전송 주기 동안 i번째 우선 순위를 가지는 단말기의 서비스 시간을,

는 i번째 우선 순위를 가지는 단말기가 CQI를 전송하지 않음으로써 절약하는 배터리 비율을 나타낸다. 보통 CQI를 전송하면 그렇지 않은 경우보다 1.5배로 전력을 소모하게 된다. Here, N is the total number of terminals located in the cell, I is the CQI transmission period,

The packet service time through data transmission,

The service time of the terminal having the i-th priority during the CQI transmission period,

Denotes a battery ratio saved by the terminal having the i-th priority not transmitting the CQI. In general, sending a CQI consumes 1.5 times the power as it would otherwise.

Through Equation 1, it can be predicted that the power consumption of the battery increases as the terminal frequently transmits the CQI to the base station.

Therefore, the terminal according to the present invention is implemented not to transmit the CQI to the base station from the moment it is determined that the channel state is kept constant. In other words, the CQI is transmitted to the base station only when the channel quality measured by the terminal deviates from a preset threshold.

The CQI transmission method according to the present invention is largely divided into 1) a process of determining a threshold value and 2) a process of transmitting a CQI based on the determined threshold value, which will be described in detail below.

The process of determining the threshold according to the present invention is as follows.

)는 아래의 수학식 2를 통해 계산할 수 있다. The terminal determines whether the channel remains constant or whether there is a change through a received signal to interference ratio (SIR). If the receiving SIR is not constant, the terminal wants to transmit a CQI, and the variation degree of the receiving SIR (

) Can be calculated through Equation 2 below.

는 i번째로 단말에 수신된 SIR을 나타내고,

는 i-1번째로 단말에 수신된 SIR을 나타낸다. 상기

이 0에 가까울수록 시간 변이에 따른 수신 SIR의 변동이 적다는 것을 알 수 있다. here,

Denotes the SIR received by the i-th terminal,

Denotes the SIR received by the i-th terminal. remind

It can be seen that the closer to 0, the less variation in the received SIR with time variation.

)의 허용치를 의미하며, 채널 상태를 세밀히 관리할 필요가 있는 경우 문턱값을 낮게 설정하여 약간의 채널 상태 변화에도 CQI 전송이 이루어지도록 한다. 반면, 처리량(throughput)에 덜 민감한 어플리케이션의 경우 문턱값을 높게 설정하여 빈번한 CQI 전송을 방지한다. 따라서, 단말기는

가 문턱값보다 큰 경우에만 CQI를 전송한다. The threshold is the degree of variation of the SIR (

), And if the channel state needs to be managed in detail, the threshold value is set low so that the CQI transmission can be performed even with a slight channel state change. On the other hand, for applications that are less sensitive to throughput, the threshold is set high to prevent frequent CQI transmissions. Therefore, the terminal

CQI is transmitted only when is greater than the threshold.

The threshold value is determined based on a data rate of a radio bearer defined during call setup. As an example, when a data rate of 2 MB or more is required per second, the threshold value is set to 0.5 to enable dynamic channel configuration, and when a data rate of 144 KB or less per second is required, the threshold value is set to 0.8. If a data rate of 144 KB to 2 MB per second is required, the threshold value is set to 0.7.

if (RB_DataRate)> = 2 Mbps

   Threshold = 0.5

else if (RB_DataRate) <= 144 Kbps

   Threshold = 0.9

else

   Threshold = 0.7

The threshold determined as described above is transmitted from the base station to the terminal during call processing. In the radio bearer setup process, the HS_THRESHOLD field is added to the "RB Information" of the "Radio Bearer Setup" message transmitted from the base station to the terminal to provide threshold information to the terminal.

2 illustrates a "Radio Bearer Setup" message according to the present invention. As shown in the figure, an HS_THRESHOLD field is added to a radio bearer setup message. In the HS_THRESHOLD field, two bits are allocated. For example, when the value is 10, the threshold value is 0.5, and when the threshold value is 0.5, the threshold value is 0.7, and when the 11 value, the threshold value is 0.9.

Now, a process of transmitting the CQI based on the threshold determined according to the present invention will be described.

3 illustrates a CQI transmission process according to an embodiment of the present invention. The terminal according to the present invention shows a CQI transmission process on the premise that the terminal has received the threshold determined as described above.

First, the warning index ALERT is set to 0 in the terminal (S21).

Subsequently, the terminal periodically or continuously monitors the HS-PDSCH channel power (S22), and measures a signal-to-interference ratio (SIR) of the channel (S23).

The difference SIR _d between the currently measured reception SIR and the reception SIR measured immediately before is calculated to check whether the SIR _d is greater than a threshold (S24). Where the SIR _d The value may be calculated through Equation 2, and the threshold is previously stored in the terminal as information provided from the base station through a "Radio Bearer Setup" message.

If the SIR _d is larger than the threshold value, it means that the change in the channel state is severe, and thus the value of the alert index ALERT is increased by 1 (S25). If the currently measured received SIR is greater than or less than a reference value than the previously measured received SIR, then the SIR _d is greater than the threshold.

Subsequently, it is checked whether the increased alert index ALERT has a value of 3 (S26), and if the alert index ALERT is 3, the terminal transmits a CQI (S27) and if the alert index ALERT is not 3, HS continues. Monitor the power of the PDSCH channel. The warning index is set such that the value increases by 1 whenever the variation of the received SIR exceeds the threshold, and the value of the warning index is 3, when the SIR _d exceeds the threshold three times. Indicates that there was.

Here, although the CQI is transmitted when the SIR _d exceeds the threshold value three times by setting the warning index to 3, the warning index to which the CQI is transmitted may be set differently. In addition, it can be implemented to send the CQI as soon as SIR _d exceeds the threshold without a warning process.

On the other hand, if the SIR _d is smaller than the threshold value, it means that the change in the channel state is not large, and thus the power of the HS-PDSCH channel is continuously monitored without performing the process of transmitting the CQI.

As described above, the method for transmitting the CQI when the SIR _d exceeds the threshold three times may be implemented using the following algorithm.

While (Monitoring_SubFrame_Period)

{

if ((│SIR _i -SIR _{i -1} │ ÷ SIR _{i -1} )> Threshold)

    ALERT ++

        if (ALERT == 3)

           Transmission_COI ();

}

Meanwhile, a method of transmitting a CQI immediately after the SIR _d exceeds the threshold by measuring the received SIR every 1 second may be implemented using the following algorithm.

While (Every_OneSecond)

{

if ((│SIR _i -SIR _{i -1} │ ÷ SIR _{i -1} )> Threshold)

       Transmission_COI ();

}

Herein, the terms or words used in the present specification and claims should not be interpreted as being limited to the ordinary or dictionary meanings, and the inventors properly define the concept of terms in order to explain their own invention in the best way. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that it can.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

As described above, the channel quality indicator transmission method of the terminal according to the present invention has the effect of reducing the power consumption of the terminal by allowing the terminal to transmit the channel quality indicator to the base station only when the channel state fluctuates severely.

Claims (9)

Receiving a reference value for transmitting a channel quality indicator from the base station; Checking the forward channel state; Calculating a variation value of a signal to interference ratio of a channel whether the variation of a signal to interference ratio of a channel in the channel state satisfies the reference value; Determining that the variation value satisfies the reference value when the variation value is less than or equal to the reference value; The terminal transmits a channel quality indicator to the base station when the variation value of the channel state does not satisfy the reference value, and the channel quality indicator when the signal to interference variation value of the channel in the channel state satisfies the reference value. And not transmitting the channel quality indicator of the terminal. delete Claim 3 was abandoned when the setup registration fee was paid. The method of claim 1, Fluctuation value of the signal-to-interference ratio

silver,

Is the i-th measured signal-to-interference ratio

Is the i-1th measured signal-to-interference ratio,

The channel quality indicator transmission method of the terminal, characterized in that calculated by. Claim 4 was abandoned when the registration fee was paid. The method of claim 1, wherein the reference value is determined according to a data transmission speed of a radio bearer. Claim 5 was abandoned upon payment of a set-up fee. 5. The method of claim 4, wherein the reference value is set lower as the data transmission rate of the radio bearer is higher. Claim 6 was abandoned when the registration fee was paid. The method of claim 1, wherein the reference value is provided through a radio bearer setup message. Claim 7 was abandoned upon payment of a set-up fee. The method of claim 1, wherein the transmitting step, The channel quality indicator of the terminal characterized in that the terminal transmits a channel quality indicator (Channel Quality Indicator) to the base station if the signal to interference ratio variation value of the channel in the channel state does not satisfy the reference value more than a predetermined number of times. Transmission method. Claim 8 was abandoned when the registration fee was paid. Receiving a reference value determined from a base station according to a data transmission speed of a radio bearer for channel quality indicator transmission; Checking a forward channel state to determine whether a variation of a signal to interference ratio of a channel in the channel state exceeds a reference value determined according to a data transmission speed of a radio bearer; The terminal transmits a channel quality indicator to the base station only when the variation in the signal to interference ratio of the channel in the channel state exceeds a reference value determined by the data transmission speed of the radio bearer more than a predetermined number of times. And transmitting the channel quality indicator of the terminal. delete

Images