KR20020093497A - Method for backward power controlling in IS-2000 Code Division Multiple Access system - Google Patents

Abstract

PURPOSE: A method of controlling reverse power in an IS-2000 CDMA system is provided to predict a channel environmental change by using a currently-received power control bit and a previously-received past power bit, and to adaptively control power control step size of a reverse closed loop circuit, thereby actively coping with the channel environmental change. CONSTITUTION: A base station determines a power control bit(ST11). When the determined power control bit is transmitted to a terminal(ST12), the terminal decides whether the power control bit is received(ST13). If so, the terminal stores the received power control bit in a memory(ST14), and analyzes patterns of the power control bit stored in the memory(ST15), then separates the analyzed power control bit patterns into three groups(ST16). The terminal controls power control step size according to the analyzed patterns(ST17), and assigns the power control step size to each of the three groups(ST18), then controls transmission power(ST19).

Description

Method for backward power controlling in IS-2000 Code Division Multiple Access system

The present invention relates to a reverse power control method capable of adaptively adjusting a power control adjustment size used for reverse closed circuit power control in an IS-95B and IS-2000 CDMA system according to a channel environment. By using the bits and past power bits received earlier to predict channel environment changes and adaptively adjust the magnitude of the reverse closed-circuit power control adjustment, the reverse link performance is more proactive in responding to channel environment changes. The present invention relates to a reverse power control method in an IS-2000 code division multiple access system.

In general, in a code division multiple access (hereinafter referred to as "CDMA") mobile communication system, the change of the received signal strength (Receive Signal Strength Indicator) at the terminal and the base station according to the distance between the base station and the terminal And the change of the received signal strength due to the topographical factors adversely affect the call quality. Therefore, as a way to compensate for this, the CDMA mobile communication system controls the power using a method called Closed Loop Power Control. It transmits a control signal from the base station (or terminal) to the terminal (or base station) that can reduce the output signal strength of the terminal (or base station) if the strength of the received signal at the base station (or terminal) is too large. Or base station) reduces the output signal strength. In addition, if the strength of the received signal from the base station (or terminal) is too small, a control signal for increasing the output signal strength of the terminal (or base station) is transmitted from the base station (or terminal) to the terminal (or base station), accordingly the terminal (Or base station) increases the output signal strength. Accordingly, the closed loop power control scheme is a power control technique that allows the base station (or terminal) to maintain the received signal strength at an appropriate size.

1 is a general conceptual diagram illustrating an operation of a power control loop including a terminal and a base station.

As shown therein, the signal power measuring unit 12 (or 22) of the terminal 10 (or base station 20) measures the signal strength of the forward (or reverse) link channel and outputs the power control bit generator ( 13) (or (23)). Then, the power control bit generator 13 (or 23) generates a corresponding power control bit by comparing the received signal strength with the reference strength. That is, the power control bit generator 13 (or 23) generates a power control bit for reducing the transmission signal of the base station 20 (or the terminal 10) when the strength of the received signal is greater than the reference, and the received signal If the intensity of the element is smaller than the reference, a power control bit for raising the transmission signal of the base station 20 (or the terminal 10) is generated. The power control bits generated as described above are inserted into the transmission signal of the terminal 10 (or the base station 20) and transmitted to the base station 20 (or the terminal 10). In this case, the operation of inserting the power control bit into the transmission signal is performed by the power control bit insertion unit 14 (or 24) of the terminal 10 (or the base station 20).

The power control bit detection unit 25 (or 15) of the base station 20 (or the terminal 10) receives the transmission signal of the terminal 10 (or the base station 20) which has been transmitted in the reverse (or forward) link. The power control bit for the forward (or reverse) link is detected from the received signal. The detected power control bits are processed by the power control bit processing unit 26 (or 16) of the base station 20 (or the terminal 10), and thus the magnitude of the transmission signal of the base station 20 (or the terminal 10). Used to adjust. At this time, the power control bit processing unit 25 (or 15) analyzes the power control bit, and if the result is to increase the strength of the transmission signal, the signal size is reduced to the transmission power control unit 27 (or 17). To do so.

The signal of the forward (or reverse) link in which the power is controlled is again forward (or reverse) by measuring the signal strength by the signal power measuring unit 12 (or 22) of the terminal 10 (or base station 20). The closed loop power control for the link is completed. The control unit 11 (or 21) of the terminal 10 (or the base station 20) sequentially appears in the conceptual diagram of FIG. 1 while controlling the closed loop power control procedure performed by the above process. It does things like send and receive data bits that aren't there.

As described above, power control techniques are used to improve call quality and increase system capacity in IS-95B and IS-2000 reverse systems. The power control technique used here consists of open circuit power control, closed circuit power control, and external circuit power control, and is used to satisfy a constant received energy-to-noise ratio (Eb / No) by receiving power control bits from a base station. This is a closed circuit power control technique.

On the other hand, in the IS-95B and IS-2000 systems, various types of power control regulation sizes have been proposed for reverse closed circuit power control, but the specification does not mention the use of various types of power control regulation sizes. The method adjusts the transmission power by a fixed power control adjustment amount according to the power control bits received by the terminal.

However, since the transmit power is controlled only by a constant power control adjustment size for one power control bit, the transmit power cannot be quickly adjusted to a sudden channel environment change, and precise transmission power control is impossible in a small channel change environment.

In addition, if the power control adjustment size is increased to cope with a sudden change in the channel environment by the existing power control method, the call quality can be kept constant, but the magnitude of interference to other terminals is increased and the terminal transmission power change is also increased. If the control size is small for precise transmission power control in a small environment, the call quality may not be overcome due to a change in channel environment.

Accordingly, the present invention is proposed to solve the above problems of the prior art,

SUMMARY OF THE INVENTION An object of the present invention is to use a current received power control bit and a previous received power bit to predict a change in the channel environment and to adaptively adjust the reverse closed circuit power control adjustment magnitude accordingly. Stores the received power control bits in the memory for a certain period of time, and anticipates the channel environment change according to the stored power control bit pattern, and adaptively changes the power control adjustment size, thereby more actively coping with the channel environment change. The purpose of the present invention is to provide a reverse power control method in an IS-2000 code division multiple access system which aims to improve link performance.

The present invention for achieving the above object,

Determining, by the base station, the power control bits, and transmitting the determined power control bits to the terminal;

Checking whether the transmitted power control bit is received at a terminal;

When the power control bit is received as a result of the check, storing the terminal in the terminal and analyzing the pattern of the stored power control bit;

Determining the power control adjustment size according to the analyzed pattern after the pattern analysis;

The method is characterized in that the terminal is configured to adjust the transmission power according to the determined adjustment size.

1 is a diagram illustrating an operation of a power control loop including a general terminal and a base station.

2 is a flowchart illustrating a reverse power control method in an IS-2000 system according to the present invention;

3 is a diagram illustrating a schematic configuration of a memory for storing power control bits for a predetermined period of time according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10 ..... Terminal

11, 21 ..... First and second control unit

12, 22 ..... First and second signal power measuring unit

13, 23 ..... First and second power control bit generator

14, 24 ..... First and second power control bit insert

15, 25 ..... First and second power control bit detector

16, 26 ..... First and second power control bit processing unit

17, 27 ..... First and second transmit power control

20 ..... Base Station

Hereinafter, a preferred embodiment of the "reverse power control method in an IS-2000 code division multiple access system" according to the present invention will be described in detail with reference to the accompanying drawings.

First, the present invention is carried out independently in a terminal and consists of three blocks. That is, the block includes a block for storing received power control bits in a memory, a block for analyzing a power control bit pattern stored in a memory, and a block for allocating a power control adjustment size according to the analyzed pattern.

2 is a flowchart illustrating a reverse power control method in an IS-2000 system according to the present invention.

As shown in FIG. 11, when the base station determines the power control bit in step ST11 and transmits the determined power control bit to the terminal in step ST12, in step ST13, the terminal determines whether the power control bit outputted from the base station is received. .

When the power control bit is received from the base station as a result of the determination, in step ST14, the terminal stores the received power control bit in a memory. In step ST15, the terminal analyzes the pattern of the power control bit stored in the memory. In ST16, the analyzed power control bit pattern is divided into three groups.

Next, in step ST17, the power control adjustment size is determined according to the analyzed pattern. In step ST8, the power control adjustment size is allocated to each of the three separated groups, and then in step ST19, the terminal adjusts the transmission power. .

A reverse power control method in an IS-2000 CDMA system having such a configuration will be described below.

First, the base station determines the power control bit and transmits it to the terminal, the terminal stores the received power control bit to analyze the power control bit pattern, and determines the power control adjustment size according to the analyzed pattern. The terminal adjusts the transmission power according to the determined power control adjustment magnitude and the received power control bit.

Here, there are three power control adjustment sizes defined in the IS-95B and IS-2000 standards, so the power control bit patterns stored in the memory of the terminal are divided into three, and the power control adjustment sizes are assigned to each. do.

For example, in the case of a memory structure capable of storing 4 bits, the power control adjustment size is allocated according to the stored power control bit pattern as follows.

1111, 0000 ⇒ 1dB

0111, 1011, 1101, 1110, 1000, 0100, 0010, 0001 ⇒ 0.5 dB

0011, 1100, 1001, 0110, 0101, 1010 ⇒ 0.25 dB

The present invention changes the transmission power rapidly by increasing the adjustment size when the channel environment is continuously in a good state or a bad state, and adjusts when the channel environment changes from a good state to a bad state or a bad state to a good state. It is a method to finely control the transmission power by reducing the size.

3 is a diagram illustrating a schematic configuration of a memory for storing power control bits for a predetermined period of time in a terminal according to the present invention.

As shown in the drawing, a memory capable of storing K power control bits is configured, and in the state where power control bits n1 to nk received in the past are stored in the terminal memory for a predetermined time, a new power control bit n0 is stored. ) Is stored in the memory, and the new power control bit n0, which was previously stored first among the power control bits n1 to nk, is stored in the first stack position n1. The previously stored power control bits n1 to nk-1 are sequentially stored in the next stage by one step.

According to the present invention described above, the "reverse power control method in the IS-2000 code division multiple access method system", by adaptively changing the power control adjustment size of the reverse closed circuit power control performed by the terminal according to the channel environment This has the advantage of improving reverse link performance.

In addition, it satisfies the current specification as it is, the terminal itself can be easily implemented without any changes in the system, and has the advantage of greatly improving system performance.

In addition, since the change in the terminal transmission power can be made small, the price of the power amplifier can be lowered, thereby lowering the price of the terminal itself.

Claims (5)

A power control method in an IS-2000 code division multiple access system, Determining a power control bit at a base station, and then transmitting the determined power control bit to a terminal; Checking whether the transmitted power control bit has been received at a terminal; If the power control bit is received as a result of the check, storing the power control bit in a memory and analyzing the pattern of the stored power control bit; Determining a power control adjustment size according to the analyzed pattern after the pattern analysis; And controlling the transmission power by the terminal according to the determined adjustment size. The method of claim 1, wherein determining the power control adjustment magnitude according to the pattern comprises: Separating into three groups according to the analyzed pattern; After the separation, determining a power control adjustment size according to the analyzed pattern; And after the power control adjustment size is determined, allocating a power control adjustment size for each of the three separated groups. 2. The system of claim 1, wherein the power control bit is changed in accordance with the received power control bit by a terminal by using the power control bit stored in the memory. Control method. 4. The method of claim 1 or 3, wherein the channel state is continuously determined using the power control bits stored in the memory. The method of claim 4, wherein the determining of the channel state comprises: If the channel environment is constantly in good or bad condition, the power control adjustment size is increased to change the transmission power drastically.If the channel environment is changed from good state to bad state or bad state to good state, A method of controlling power in an IS-2000 code division multiple access system, characterized in that the transmission power is finely adjusted by reducing the adjustment size.