KR100376581B1 - A method of controlling a power of IMT-2000 system - Google Patents

Abstract

The present invention relates to a power control method in a next generation mobile communication system in which an uplink outer loop power control is efficiently performed by optimizing a threshold in an asynchronous IMT-2000 system applying the 3GPP standard. In the power control method of the next generation mobile communication system, the first step of extracting the frame error rate of the received frame by the control station using the value of the field indicating the error detection result in the uplink dedicated channel data frame structure of the 3GPP standard; And a second process of transmitting an adjustment amount of a threshold value to a base station by comparing a frame error rate of the extracted received frame with a predetermined reference frame error rate, and controlling for uplink outer loop power control in an asynchronous IMT-2000 system. By adjusting the threshold value based on the error rate of the frame received by the station, power control is precisely performed even in the 3GPP-compliant IMT-2000 system, which enables user to maintain sound quality, system capacity and mobile terminal. It is possible to reduce the average transmit power of.

Description

Power control method in next generation mobile communication system {A method of controlling a power of IMT-2000 system}

The present invention relates to a power control method in a next generation mobile communication system, and more particularly, to a method for implementing outer loop power control in a third generation IMT-2000 system.

The third generation mobile communication system, called International Mobile Telecommunications (IMT-2000), is a mobile communication system making recommendations in the TG / 1 of ITU-R aimed at service in the early 2000s. According to the mobile user's request, the mobile communication system allows a wireless link to access various communication services supported by a fixed communication network such as PSTN / ISDN / B-ISDN.

The frequency bands used are 1,885 MHz to 2,025 MHz and 2,110 MHz to 2,200 MHz, which are determined by WARC-92, and not only provide existing communication services but also provide a higher level of service by improved technology.

IMT-2000 is able to interoperate with various systems, has high service compatibility by worldwide operation, and has the features of using small size and light weight terminal with high quality.

IMT-2000 is a mobile communication system that provides not only voice and data but also ISDN-class and several Mb / s multimedia services.It is designed to maximize the frequency efficiency and to generate the minimum number of handovers for various moving speeds. It provides the service by integrating existing cellular, PCS, satellite mobile communication system by introducing the concept of micro, macro cell, etc.).

In addition, IMT-2000 uses a total of 230 MHz in the common frequency band (1,885 MHz to 2,025 MHz, 2,110 MHz to 2,200 MHz) worldwide, and the satellite portion of the IMT-2000 is limited to the bands 1,980 to 2,010 MHz and 2,170 to 2,200 MHz. As a result, international roaming is possible because it uses a common wireless standard.

In this way, IMT-2000 integrates the existing terrestrial mobile communication and satellite mobile communication systems so that the mobility of the terminal can be freely moved, the personal mobility that the subscriber can receive from any terminal, and the voice on the go. It aims to satisfy the service mobility and the like that can be used.

In other words, IMT-2000 is a third generation mobile communication system that integrates existing mobile communication systems to provide international roaming services, multimedia services, and personalized communication services.

As the standardization of IMT-2000 is compressed into two standards of Europe and Japan versus the United States of America, the standard specification is being prepared by grouping 3GPP in Europe and Japan and 3GPP-2 in the United States.

3GPP, led by Europe and Japan, is working on third-generation GSM networks and asynchronous W-CDMA access technologies and terminal technologies based on them.

The US-led 3GPP-2 is studying synchronous CDMA 2000 access technology and terminal technology based on the ANSI-41 network.

In the asynchronous IMT-2000 system applying the 3GPP standard, the power control method includes inner loop power control, open loop power control, and open loop power control in both downlink and uplink. There is an outer loop power control.

The open loop power control is a method of setting its own transmission power based on the received signal to interference ratio (SIR) or Ec / No, and is used for random access of a mobile terminal or initial transmission power of a downlink channel. .

The inner loop power control is a method of adjusting a transmission power of a transmitting side by determining a transmission power control (TPC) bit by comparing the SIR of the received signal with a threshold value and transmitting the transmission power control (TPC) bit. This inner loop power control method is 0.625msec, so it can be applied to a sudden change of wireless environment, and the accuracy is excellent.

The outer loop power control serves to adjust a threshold applied to the closed loop power control. If the closed loop power control is applied using the current threshold and the TPC bit is set to "0" continuously to require the transmitter to lower its power, it means that the current threshold is generally set higher, and vice versa. In this case, since the threshold is set low, an algorithm for setting an optimal threshold is required.

In order to efficiently apply the inner loop power control method, an optimal threshold value is important.

Applying the inner loop power control based on the lower set threshold is expected to degrade the call quality by setting the TPC bit to set the receive SIR too low. In addition, if the inner loop power control is applied based on a high threshold value, the wireless capacity may be reduced.

This causes a decrease in radio capacity because the power at the transmitting side is set to maintain a high SIR due to the high threshold and acts as an interference for other channels.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional situation, and has been developed to optimize the threshold in an asynchronous IMT-2000 system to which the 3GPP standard is applied, so that uplink outer loop power control can be efficiently performed. Its purpose is to provide a control method.

1 is a diagram showing an interface protocol of a control station and a base station in 3GPP to which the method of the present invention is applied;

2 is a structural diagram of an uplink dedicated channel data frame employed in an embodiment of the present invention;

3 is a diagram illustrating a power control threshold adjustment pattern according to an embodiment of the present invention.

※ Explanation of code for main part of drawing

10: dedicated channel frame protocol

12a-12n: error detection indicator field

14: Quality Evaluation Field

In order to achieve the above object, a power control method in a next generation mobile communication system according to a preferred embodiment of the present invention, in the power control method of an asynchronous next generation mobile communication system applying the 3GPP standard,

A first step of extracting, by a control station, a frame error rate of a received frame using a value of a field indicating a result of error detection in an uplink dedicated channel data frame structure of the 3GPP standard; And a second process of transmitting the adjustment amount of the threshold value to the base station by comparing the extracted frame error rate of the received frame with a predetermined reference frame error rate.

Hereinafter, a power control method in a next generation mobile communication system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

The method of the embodiment of the present invention is performed by changing whether or not the threshold is adjusted by the control station (RNC) and the amount of adjustment to the base station (Node-B) to change the threshold applied by the base station to the inner loop power control. Accordingly, in order to find out the parameters that can be extracted from the control station, it is necessary to first understand the 3GPP specification.

In 3GPP, an interface between a control station and a base station is defined as an Iub interface, and the format thereof is defined as shown in FIG.

1 is a diagram illustrating an interface protocol between a control station (RNC) and a base station (node-B) in 3GPP to which the method of the present invention is applied. Dedicated Channel (DCH) which is transmitted, which is matched using DCH Frame Protocol (FP) 10.

That is, all user data transmitted between the control station and the base station is transmitted in the form of the DCH FP 10.

FIG. 2 is a structural diagram of an uplink dedicated channel data frame employed in an embodiment of the present invention, showing a structure of an uplink dedicated channel data frame associated with an embodiment of the present invention among DCH FPs in an Iub interface defined by 3GPP. Drawing.

User data via the Iub interface is transmitted in the format of FIG.

Therefore, in order to perform uplink outer loop power control at the control station, predetermined parameters included in FIG. 2 are used.

In addition, since the uplink dedicated channel data frame of FIG. 2 is transmitted with a transmission time interval (TTI), a minimum period of threshold adjustment becomes the TTI.

On the other hand, the parameters that can be used to adjust the thresholds are Cyclic Redundancy Check Indicator (CRCI) 12a-12n and Quality Estimate (QE) 14.

The error detection indicator fields 12a to 12n indicate CRC results in units of a transport block (TB) of a dedicated channel (DCH). If the value of the CRCI field is "0", it indicates normal. If the value of the CRCI field is "1", it indicates abnormality.

The QE field 14 indicates a radio quality of a corresponding dedicated channel (DCH), and represents a bit error rate (BER) of a transport channel or a physical channel in log scale.

In the embodiment of the present invention, only the CRCIs 12a to 12n are used, and the QE 14 may be used in a handover situation.

In the embodiment of the present invention, the frame error rate (FER) is used as an index for evaluating the current radio quality to adjust the threshold.

The frame error rate FER is obtained by the following equation, "FER = (CRCI error block) / (total block)".

The above equation represents the ratio of the transport block TB with the CRCI of “1” (abnormal) and the entire block in the frame received from the control station RNC, which corresponds to the FER of the received frame.

The FER of the received frame is calculated by collecting a predetermined number of consecutive frames (eg, three). This value takes into account the power control delay of the mobile terminal.

When the FER of the received frame is calculated, the control station (RNC) compares the pre-stored reference FER with the result of the detected received FER to determine the up / down of the threshold value.

FIG. 3 is a diagram illustrating a power control threshold adjustment pattern according to an embodiment of the present invention, and illustrates a variation of the FER of a received frame detected for threshold adjustment.

After detecting the FER of the received frame, the threshold is lowered step by step when the FER of the received frame is low compared to the current reference FER. The FER of the received frame is then increased step by step.

If the FER of the received frame is close to the maximum allowable FER, call quality deteriorates as much. In this case, call disconnection may occur. Therefore, if the closest FER is close to the maximum allowable FER, the reference FER is rapidly lowered. Prevent.

Finally, an embodiment of the present invention extracts the FER using the "CRCI" parameter among the parameters provided in the dedicated channel frame protocol to implement uplink outer loop power control, and adjusts the threshold value using the extracted FER. The extracted FER at the time is made in the pattern as shown in FIG.

In other words, the threshold is adjusted to the maximum threshold ("a") at which the FER of the receiving frame to measure exceeds the maximum allowable FER, and by this adjustment the reference FER is drastically lowered. When the threshold is gradually lowered, the reference FER is increased again. Accordingly, when the reference FER exceeds the maximum allowable FER, the reference FER is drastically lowered by adjusting the instant to the maximum threshold again. The pattern of FER extracted in this way is achieved.

For example, if the error rate is calculated for three consecutive frames that are input and the frame error rate is much larger than the threshold, the threshold is increased a lot, and if the frame error rate is slightly larger than the threshold, the corresponding error is correspondingly. Raise the threshold a little.

On the contrary, when the error rate for the three consecutive frames is smaller than the threshold, the threshold is lowered accordingly.

When the error rate for the three consecutive frames is equal to the threshold, there is no variation in the threshold.

As described in detail above, according to the present invention, the IMT of the 3GPP standard is performed by performing an optimized threshold adjustment based on an error rate of a frame received at a control station for uplink outer loop power control in an asynchronous IMT-2000 system. Power control is precisely performed in the -2000 system, thereby maintaining the user's sound quality and reducing the system capacity and the average transmission power of the mobile terminal.

On the other hand, the present invention is not limited only to the above-described embodiment, but can be modified and modified within the scope not departing from the gist of the present invention, the technical idea to which such modifications and variations are also applied to the claims Must see

Claims (6)

In the power control method of the asynchronous type next generation mobile communication system applying the 3GPP standard, The control station extracts a frame error rate (FER) of a received frame using a value of a Cyclic Redundancy Check Indicator (CRCI) field indicating a result of error detection in an uplink dedicated channel data frame structure of the 3GPP standard. A first step of determining a frame error rate based on a ratio of CRCI error blocks to all blocks of a corresponding received frame; And The threshold value is adjusted stepwise by comparing the frame error rate of the extracted received frame with a predetermined reference frame error rate, and the frame error rate of the received frame is increased to the maximum allowable frame error rate by the threshold value gradually lowered by the adjustment. And a second process of adjusting the threshold by rapidly lowering the reference frame error rate to a preset value and transmitting the adjusted amount to the base station every time the adjusted amount is adjusted. . delete The method of claim 1, The first step is a power control method of the next generation mobile communication system, characterized in that to extract a frame error rate by collecting a predetermined number of frames received continuously. The method of claim 1, The second process transmits a control signal for gradually decreasing the threshold value when the frame error rate of the extracted received frame is lower than the reference frame error rate, and the threshold when the frame error rate of the extracted received frame is higher than the reference frame error rate. Power control method in the next generation mobile communication system, characterized in that to send a control signal for increasing the value step by step. delete The method of claim 1, The second process is a power control method in a next generation mobile communication system, characterized in that the transmission period of the uplink dedicated channel data frame as the minimum period of the threshold adjustment.