KR100384861B1 - The Method for Power Control of Mobil Communication System - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a power control method of a mobile communication system.

2. The technical problem to be solved by the invention

The present invention relates to a power control method of a mobile communication system for reducing interference between channels on a network and solving a source problem between a base station and a terminal station. To provide a closed loop power control method using a finger energy as a reference and a computer-readable recording medium recording a program for implementing the methods.

3. Summary of Solution to Invention

The present invention relates to an open loop power control method applied to a power control system of a mobile communication system, wherein a reception sensitivity (RSSI) value of a base transceiver station (hereinafter referred to as a BTS) is received from a paging channel. Determining a correction value according to the received RSSI value, calculating a random access power using the received RSSI value and the determined correction value, and then attempting random access according to the calculated random access power; A second step of checking and ending if the random access succeeds, and attempting random access again according to the new random access power obtained by adding a stepsize to the calculated random access power; And a third step of repeating the second step with respect to the new random access power obtained by adding the stepsize to the random access power.

4. Important uses of the invention

The present invention is used in a CDMA mobile communication system.

Description

Power control method of mobile communication system {The Method for Power Control of Mobil Communication System}

The present invention relates to a power control method of a mobile communication system, and more particularly, in a power control method of a mobile communication system for reducing interference between channels on a network and solving a root problem between a base station and a terminal station. Open loop power control method with corrected parameter value, closed loop power control method using finger energy of magnetic channel as a reference, and a computer-readable recording medium recording a program for implementing the methods. It is about.

The power control algorithm used in the conventional CDMA system can be divided into three types.

The first is an open loop forward power control used to determine the first random access power value when attempting a call to a terminal station, and the second is a closed loop used in both forward and reverse directions after link establishment. (closed loop) Power control. Finally, the third is an outer loop that measures the Frame Error Rate (FER) for a period of time and changes the reference threshold value of the reverse power control accordingly. (outer loop) Power control.

However, the third outer loop power control, which is performed at the network level, is excluded, and the problems with the remaining two power controls are as follows.

First, in the case of open loop power control, the algorithm used to determine the random access power value when the terminal station attempts the first call is determined by Equation 1 below.

Initial Random Access Power = -73-RSSI of Terminal Receive Power (dBm)

When the first random access fails, the random access power value in the second or more attempts is as shown in Equation 2 below.

Random access power = -73-RSSI of terminal received power + stepsize * N (dBm)

(Where N is the number of random access failures)

In this case, however, if there are already many reverse channels in the base station cell, the number of failures of random access will increase, and thus, random access will succeed with such a high power value. Affecting the power supply, resulting in an increase in the reverse power value.

That is, since the initial random access value is set to a constant value irrespective of the wireless environment in the base station cell, the overall wireless environment is close to saturation state, and there is a problem in that capacity increase becomes difficult.

Next, the closed loop power control used in the reverse and forward links generally has the following algorithm.

Algorithm 1

If (measured Eb / No)> (reference Eb / No), power reduction command to terminal station

Power increase command to Else terminal station

(Eb is energy value per bit of magnetic channel, No is total noise power density)

However, many small and medium-sized companies have difficulties in measuring Eb / No in the case of their own CDMA modems. According to the IS-95A / B / C standard, fast reverse link power control should be performed every 2ms because the fluctuation of the No value is too severe to obtain an accurate value during that time. to be. (It is known that about 20ms is required to obtain a relatively accurate No value by domestic technology.)

Therefore, when power control is performed in this state, an incorrect Eb / No value is used, or power control is too slow to cope with a situation such as multipath fading in a wireless environment.

The present invention proposed to solve the above problems, in the power control method of the mobile communication system to reduce the interference between channels on the network and to solve the root problem between the base station and the terminal station, a variable value representing a wireless environment To provide a corrected open loop power control method and a closed loop power control method using a finger energy of a magnetic channel as a reference, and a computer-readable recording medium recording a program for implementing the methods. The purpose is.

1 is a flow chart of an embodiment of a power control method of a mobile communication system according to the present invention;

2 is a flowchart of another embodiment of a power control method of a mobile communication system according to the present invention;

In accordance with another aspect of the present invention, there is provided an open loop power control method applied to a power control system of a mobile communication system, the reception sensitivity of a base transceiver station (hereinafter referred to as a BTS) from a paging channel ( Receiving a RSSI) value to determine a correction value according to the received RSSI value, calculating a random access power using the received RSSI value and the determined correction value, and then performing random access according to the calculated random access power. A first step of attempting; A second step of checking and ending if the random access succeeds, and attempting random access again according to the new random access power obtained by adding a stepsize to the calculated random access power; And a third step of repeating the second step with respect to the new random access power obtained by adding the step size to the random access power.

The present invention also provides a power control system having a processor to receive a RSSI value of a BTS from a paging channel to determine a correction value according to the received RSSI value, and to use the received RSSI value and the determined correction value. A first function of attempting random access according to the calculated random access power after calculating a random access power; A second function of terminating after checking if the random access succeeds and attempting random access again according to the new random access power obtained by adding the step size to the calculated random access power; And a computer-readable recording medium having recorded thereon a program for realizing a third function of repeatedly performing the second function with respect to the new random access power obtained by adding the step size to the random access power.

On the other hand, the present invention for achieving the other object, in a closed loop power control method applied to a power control system of a mobile communication system, the cell loading rate (cell loading) every time corresponding to a certain period from the reference time (cell) a first step of calculating a loading ratio and determining an Eb / No [th] (Threshold Value of Eb / No) value accordingly; A second step of obtaining an expected power value by comparing the determined Eb / No [th] value and Eb / No [cal] (Calculated Eb / No) value; And a third step of instructing increase or decrease of power for the terminal station through comparison of the estimated power value and the finger energy value.

In addition, the present invention, in the power control system having a processor, calculates the cell loading ratio for each time corresponding to a certain period from the reference time, and accordingly Eb / No [th] (Threshold Value of Eb / No) first function of determining a value; A second function of obtaining an expected power value by comparing the determined Eb / No [th] value with an Eb / No [cal] (Calculated Eb / No) value; And a computer-readable recording medium having recorded thereon a program for realizing a third function of instructing increase or decrease of power to a terminal station by comparing the estimated power value and finger energy value. to provide.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flow chart of an embodiment of a power control method of a mobile communication system according to the present invention, and is an open loop power control method.

As described above, in the conventional open loop power control method, since the initial random access value is set to a constant value irrespective of the radio environment in the base station cell, the radio environment generally becomes close to saturation, thereby increasing capacity. Since there is a problem that becomes difficult, it will be able to overcome this by correcting the variable value representing the wireless environment in the equation (1).

Therefore, the core of the open loop power control method of the mobile communication system according to the present invention is that the change of the wireless environment is used to determine the initial random access power value.

Accordingly, the first conceivable variable is the number of users currently talking in the base station cell. That is, when the number of users is small in the cell, the access is attempted with a small power value, and when the number of users is large, the access is attempted with a larger value.

However, in general, it can be assumed that in IS-95C or IMT-2000 system, various data rates exist according to users, and their impact on wireless environment is different. It would not be possible, but rather a better parameter could be an RSSI value representing the base station's input power value.

That is, as shown in FIG. 1, in the open loop power control method of the mobile communication system according to the present invention, first, the RSSI value is periodically transmitted to the terminal station through the paging channel of the base station (110). The station determines a correction value by referring to the RSSI vs. random access correction value table (120), and then uses the determined correction value to determine an initial random access value as shown in Equation 3 below (130).

Random access power = -73-RSSI + correction value (dBm) of terminal receive power

At this time, the 'RSSI vs random access correction value table' is a database constructed by field tests, and is configured to have a larger correction value when the input power of the base station is large.

Next, an initial random access is attempted using the random access power determined by Equation 3 above (140), and if the attempt is successful (150), the procedure ends. At step 160, the random access power is added to the step size, and then random access is attempted at step 170.

In this case, if the second and subsequent random accesses also fail, the random access attempt is repeated with the step size added to the previous random access power again.

2 is a flowchart illustrating another embodiment of a power control method of a mobile communication system according to the present invention, and illustrates closed loop power control.

As described above, in the conventional closed loop power control method, an incorrect Eb / No value is used or power control is performed too slowly to cope with a situation such as multipath fading in a wireless environment. Since there is a problem that the current domestic technology can be overcome by using an algorithm that makes Eb (energy per bit of magnetic channel) value that can be measured relatively accurately in a short time as a reference value of the power control.

Of course, in this case, the Eb / No value is used, but only as an auxiliary means, and the measured value for a long time (e.g. 20 ms) that the influence of the fluctuation of the No value disappears to some extent is eliminated. Since it is used, it does not matter much.

That is, as shown in Figure 2, in the closed loop power control method of the mobile communication system according to the present invention, by using a variable of the expected power (Expected Power) having the same meaning as the Eb value as a reference value of the power control, the basic closed Loop power control instructs the terminal station to increase or decrease the output power by measuring the finger energy of the magnetic channel every 2ms and comparing the value with the expected power that is the reference of the power control.

Looking at the above process in more detail as follows.

First, in order to measure the value of Eb, it is determined whether 20 ms has been reached from the reference time (210), and if the result of the determination is 20 ms, a cell loading ratio is calculated (220), and the calculated cell loading rate is determined. The Eb / No [th] value is determined according to the 'cell loading rate vs Eb / No [th] table' (230).

Next, by comparing the determined Eb / No [th] value with the calculated Eb / No [cal] value (240), if the Eb / No [cal] value is larger, the Eb value in the present invention. The expected power used in the same sense is increased by 1 (250), and if not large, the expected power is decreased by 1 (260).

In addition, by comparing the estimated power determined by the above process with the magnitude of the finger energy (270), if the value of the finger energy is larger, the terminal station is commanded to increase the power (280). If the value of the finger energy is not greater, the terminal station is commanded to decrease power (290).

At this time, if it is determined that 20 ms has been reached from the reference time (210), if 20 ms has not passed from the reference time, the above calculation and comparison process (220 to 260) is omitted, and immediately the expected power (Expected Power) and finger energy ( Finger energy) is compared with the process (270).

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains, and the above-described embodiments and accompanying It is not limited to the drawing.

As described above, the present invention not only increases the success rate of the initial access by referring to the RSSI value of the base station, which is a variable representing the state of the wireless environment, in determining the power value when the initial terminal station attempts random access. By allowing the access to succeed with a minimum power value, it is possible to reduce the influence on other channels in the cell of the same base station.

In addition, the present invention, by using a finger energy (Finger Energy) of the magnetic channel, which can be measured in a relatively stable within a short time as a reference (Reference), there is an effect that can enable a stable power control with a more plain technology .

Claims (10)

In an open loop power control method applied to a power control system of a mobile communication system, Receiving a sensitivity value (RSSI) of a base transceiver station (hereinafter referred to as a BTS) from a paging channel to determine a correction value according to the received RSSI value, and randomly using the received RSSI value and the determined correction value. After calculating access power, attempting random access according to the calculated random access power; A second step of checking and ending if the random access succeeds, and attempting random access again according to the new random access power obtained by adding a stepsize to the calculated random access power; And A third step of repeatedly performing the second step on the new random access power obtained by adding the stepsize to the random access power; Open loop power control method comprising a. The method of claim 1, The correction value is, And obtaining the correction value using the correction value table according to the received RSSI value. The method according to claim 1 or 2, The random access power is, Random access power = -73-Open loop power control method, characterized in that calculated according to the formula of the RSSI + correction value (dBm) of the terminal received power. In a closed loop power control method applied to a power control system of a mobile communication system, A first step of calculating a cell loading ratio for each time corresponding to a predetermined period from a reference time, and determining an Eb / No [th] (Threshold Value of Eb / No) value accordingly; A second step of obtaining an expected power value by comparing the determined Eb / No [th] value and Eb / No [cal] (Calculated Eb / No) value; And A third step of instructing increase or decrease of power to the terminal station by comparing the estimated power value and the finger energy value; Closed loop power control method comprising a. The method of claim 4, wherein A fourth step of directly performing a third step in the case of a time not corresponding to a predetermined period from the reference time; Closed loop power control method further comprising. The method according to claim 4 or 5, The second step, As a result of comparing the determined Eb / No [th] value with the Eb / No [cal] value, if the value of Eb / No [cal] is larger, the expected power value is increased by 1; otherwise, the estimated power value is expected. Closed loop power control method characterized in that the value of Power) is decreased by one. The method according to claim 4 or 5, The third step, As a result of comparing the estimated power value with the finger energy value, if the finger energy value is larger, the power for the terminal station is increased. Closed loop power control. In a power control system with a processor, Receiving a sensitivity value (RSSI) of a base transceiver station (hereinafter referred to as a BTS) from a paging channel to determine a correction value according to the received RSSI value, and randomly using the received RSSI value and the determined correction value. A first function of attempting random access according to the calculated random access power after calculating an access power; A second function of terminating after checking if the random access succeeds and attempting random access again according to the new random access power obtained by adding a stepsize to the calculated random access power; And A third function of repeatedly performing the second function on a new random access power obtained by adding a stepsize to the random access power; A computer-readable recording medium having recorded thereon a program for realizing this. In a power control system with a processor, A first function of calculating a cell loading ratio for each time corresponding to a predetermined period from a reference time, and determining an Eb / No [th] (Threshold Value of Eb / No) value accordingly; A second function of obtaining an expected power value by comparing the determined Eb / No [th] value with an Eb / No [cal] (Calculated Eb / No) value; And A third function of instructing increase or decrease of power for the terminal station by comparing the estimated power value and the finger energy value; A computer-readable recording medium having recorded thereon a program for realizing this. The method of claim 9, A fourth function for performing a third function directly in case of a time not corresponding to a predetermined period from the reference time A computer-readable recording medium that records a program for further realization.