KR20070023062A - Method for power control of mobile telecommunication system - Google Patents

Abstract

The present invention provides a mobile communication system capable of selectively adjusting the maximum power level of the terminal according to the noise margin of the base station to maximize the number of terminals that can be called even in a poor reception environment and to ensure the call quality above a certain level. Regarding the power control method,

A power control method of a mobile communication system according to the present invention is a power control method of a mobile communication system for controlling a power level between a mobile communication terminal and a base station, the signal-to-interference ratio (measurement of the channel signal transmitted from the mobile communication terminal to the base station) SIR) and a target signal-to-interference ratio (Target SIR), and when the <measurement SIR> is smaller than the <Target SIR>, the sum of the received power received by the base station (P) and the base station can accommodate Comparing a threshold received power Pth, and if the sum P of the received powers is less than the threshold received power Pth, the difference Pth between the threshold received power Pth and the sum of received powers Pth; -P) divided by the total number N of terminals connected to the corresponding base station ((Pth-P) / N) as a reference transmission power increase value, and considering the <measurement SIR> of each terminal, A predetermined value from the reference transmission power rise value Applying differentiated or in addition, each of the transmission power value increases in each terminal to is characterized in that comprises a step of increasing the transmission power by a rise up to a power level of each terminal.

Power control

Description

Power control method of mobile communication system {Method for power control of mobile telecommunication system}

1 is a configuration diagram of a mobile communication system.

2 is a block diagram of a mobile communication terminal.

3 is a flowchart illustrating a power control method of a mobile communication system according to the present invention.

The present invention relates to a power control method of a mobile communication system. More particularly, the maximum power level of a terminal can be selectively adjusted according to a noise margin of a base station to maximize the number of terminals that can be called even in a poor reception environment. The present invention relates to a power control method of a mobile communication system capable of guaranteeing a certain level of call quality.

The mobile communication system uses an analog cellular system called a first generation system and a second generation system is currently used. Second-generation systems such as GSM, PDC, CDMA ONE (IS-95) and US-TDMA (IS-136) have been developed primarily for the transmission of voice communications in wireless environments and have contributed significantly to the development of the wireless communications market. .

Recently, third generation systems have been developed for the purpose of multimedia transmission. The third generation system has advantages such as high-definition image service, fast data rate, and the like, and the representative third generation system is wide-band code division multiple access (WCDMA). WCDMA is developing 3GPP (3th Generation Projection Group) including Europe, the United States, and Japan to develop technical specifications.

On the other hand, since CDMA of the second generation system or WCDMA of the third generation system uses the same frequency band at the same time by several subscribers and the base stations, interference between the call sites or the base stations is caused. Accordingly, power control is indispensable for maximizing the call capacity of the base station and the neighboring base station, extending the battery life of the mobile communication terminal, and ensuring uniform call quality.

Power control includes open loop control, closed loop power control, forward power control, and outer loop control, among which closed loop power control is the minimum that the base station can receive the output of the mobile communication terminal during a call. It is performed to make power, which maximizes the base station reverse call capacity and extends the battery life of the terminal.

Looking at the closed-loop power control process in more detail, the terminal and the base station receives the channel signal of the other party and the magnitude of the received channel signal, that is, signal to interference ratio (SIR) ) Is measured and compared with a predetermined size of the corresponding SIR, that is, a target signal-to-interference ratio (<Target SIR>, hereinafter referred to as '<Target SIR>'), the <measurement SIR> of the received channel signal is <Target SIR If it is lower than>, the other party is requested to increase power. If the <Measurement SIR> is higher than <Target SIR>, the command is called to lower power to the other party, that is, a TPC command (Transmitter Power Control command). send through subchannel). For reference, the signal-to-interference ratio (SIR) may be expressed as energy of carrier / interference of other`s (Ec / Io).

Through such a power control process, the power level of the terminal and the like can be raised to ensure a certain level of call quality. However, since the maximum power level is set in the terminal, the power level cannot be increased above the predetermined maximum power level. Normally, the maximum power level of the terminal is set to about 24 dBm. Accordingly, when the reception environment of the terminal is poor, even if the power level is increased to the maximum power level, the call connection may not be made. In addition, when a call is connected using the maximum power level, the call connection of another terminal connected to the base station may be disturbed according to the noise margin of the base station. Here, the noise margin refers to the number of terminals connected to the maximum number of terminals that the base station can accommodate.

The present invention has been made to solve the above problems, by selectively adjusting the maximum power level of the terminal according to the noise margin of the base station to maximize the number of terminals that can be called even in a poor reception environment and improve the call quality An object of the present invention is to provide a power control method of a mobile communication system that can be secured to a certain level or more.

In the power control method of the mobile communication system according to the present invention for achieving the above object, in the power control method of the mobile communication system for controlling the power level between the mobile communication terminal and the base station, a channel transmitted from the mobile communication terminal to the base station Comparing the signal-to-interference ratio (measurement SIR) and the target signal-to-interference ratio (Target SIR) of the signal, and if the <measurement SIR> is less than the <Target SIR>, the sum (P) of received powers received at the base station And comparing the threshold received power Pth that the base station can accommodate; and if the sum P of the received powers is less than the threshold received power Pth, the sum of the threshold received powers Pth and the received powers. (Pth-P) divided by the total number (N) of terminals connected to the corresponding base station ((Pth-P) / N) as a reference transmission power increase value, and < Taking into account the measurement SIR> Subtracting or adding a predetermined value from the power increase value to apply the differential transmission power rise value to each terminal to increase the maximum power level of each terminal by the transmission power rise value. .

Preferably, the transmission power rise value applied to the terminal having a relatively low <measurement SIR> is relatively higher than the transmission power rise value applied to a terminal having a relatively high <measurement SIR>.

Preferably, when the sum P of the received powers received by the base station is compared with the threshold received power Pth that the base station can accommodate, and the sum P of the received powers is greater than the threshold received power Pth. Based on a value ((P-Pth) / N) obtained by dividing the difference (P-Pth) between the sum of received power (P) and the threshold received power (Pth) by the total number (N) of terminals connected to the corresponding base station. It is assumed that the transmission power drop value is subtracted or added to the reference transmission power drop value by considering the < measurement SIR > The maximum power level is lowered by the transmission power drop value.

Preferably, when the sum P of the received powers received by the base station is compared with the threshold received power Pth that the base station can accommodate, and the sum P of the received powers is greater than the threshold received power Pth. In addition, the maximum power level of each terminal is lowered by 1 to 2 dBm uniformly with respect to all terminals connected to the corresponding base station.

Preferably, considering the <measurement SIR> of each terminal connected to the base station, the maximum power level is selectively lowered by 1 to 1 dBm for the terminal where the <measurement SIR> is relatively high.

According to a feature of the present invention, the maximum power level of a terminal connected to the corresponding base station is increased or lowered depending on the receiving environment of the terminal in consideration of the noise margin of the base station, the sum of the received power of the base station, the threshold received power, and the like. As a result, it is possible to reliably secure the call connection and the call quality of the terminal.

Hereinafter, a power control method of a mobile communication system according to the present invention will be described in detail with reference to the accompanying drawings. 1 is a block diagram of a mobile communication system, FIG. 2 is a block diagram of a mobile communication terminal, and FIG. 3 is a flowchart illustrating a power control method of a mobile communication system according to the present invention.

As shown in FIG. 1, the mobile communication system includes a mobile communication terminal 100, a base station 110 and a switch 120 that mediate wireless communication between the mobile communication terminal 100, and a home location register (HLR) ( 130).

In detail, the base station 110 includes a base station transmission system (BTS) 112 for performing a wireless connection between the mobile communication terminal 100 and a wireless connection between the mobile communication terminals, and a plurality of base stations. A base station controller (BSC) 111 that controls the transmission system 112 and performs call mobility management and the like related to call processing. The switch 120 plays a role of transmitting and receiving data and control signals between other communication networks such as a PSTN, an Internet network, or between lower networks of base stations of the same operator. The home location register (HLR) 130 performs location registration of the mobile communication terminal and stores profile information of the calling and receiving terminals. Here, the profile information refers to a mobile identification number (MIN), an electronic serial number (ESN) of the mobile communication terminal, and / or mobile communication service information of a subscribed terminal.

Meanwhile, as shown in FIG. 2, the mobile communication terminal includes a terminal controller 201, a wireless transceiver 202, a RASRAM 203, and the like, and the terminal controller 201 includes an MSM. (Mobile Station Modem) and the like to control the power of the wireless signal transmitted through the wireless transceiver 202 according to the maximum power level set in the RASRAM (203). Here, the maximum power level is set in consideration of SAR (Specific Absorption Ratio), network management and other requirements, and the maximum power level may be selectively changed by a noise margin, etc. A detailed description thereof will be described later. .

The power control method in the mobile communication system having the above configuration, that is, the power control method of the mobile communication system according to the present invention will be described. First, as shown in FIG. 3, the received electric field strength of the channel signal of the mobile communication terminal is measured. Specifically, the base station receives the channel signal from the mobile communication terminal (S301) and measures the magnitude of the channel signal, that is, the signal-to-interference ratio (SIR) (S302). Subsequently, a <measurement SIR> and a target signal-to-interference ratio <Target SIR> of the received channel signal are compared. Here, the <Target SIR> refers to an appropriate power level required for smooth wireless communication, and is preset in the terminal, and the signal-to-interference ratio (SIR) is Ec / Io (energy of carrier / interference of other`s). It may be represented by.

As a result of the comparison between the <measurement SIR> and <Target SIR>, the <measurement SIR> may be larger or smaller than the <Target SIR>. However, the present invention aims to selectively vary the maximum power level of the terminal as indicated in the problem to be achieved by the present invention. Therefore, if the <measurement SIR> is higher than the <Target SIR> means that the reception environment of the terminal is good, so the relevant part is out of the question, and the case where the <measurement SIR> is smaller than the <Target SIR> It will be described.

If the <measurement SIR> is less than <Target SIR> (S303), the mobile communication terminal transmits a message about the maximum power level value allowable by the base station to the base station through the traffic channel (S304). When the base station receives such a message from the terminal, it first calculates a noise margin. That is, the total number N of terminals connected to the base station is calculated, and the total P of received powers received by the base station is calculated.

Then, the sum P of the received powers is compared with a threshold received power (Pth) that the base station can accommodate. As a result of the comparison, if the total sum P of the received powers is less than the threshold received power Pth, it means that there is room to increase the transmission power of the mobile communication terminal, and the sum P of the received powers is the threshold received. If the power Pth is larger than that, there is no room for increasing the transmission power of the mobile communication terminal.

First, when the sum P of the received powers P is smaller than the threshold received power Pth (P <Pth), a step (S305) shows that the sum of the threshold received power Pth and the received power P of the base station is determined. It is possible to accommodate the transmission power as much as the difference Pth-P. In this case, since a plurality (N) terminals are connected to the base station, the average possible rise value Pmean_up of each terminal is expressed by As shown in Equation 1>, the difference between the sum of the threshold reception power Pth and the reception power P is divided by the number N of terminals ((Pth-P) / N) (S306).

Pmean_up = (Pth-P) / N

Where Pth is the threshold received power, P is the sum of received power, and N is the total number of terminals connected to the base station.

As shown in Equation 1, each terminal connected to the base station can increase the transmission power by Pmean_up on average. However, if the average possible rise value Pmean_up of the transmission power of each terminal is equally applied to each terminal to increase the transmission power of each terminal by the Pmean_up, the reception environment of each terminal is not considered. . That is, it is not necessary to apply the same transmission power rise value to a terminal in which the reception environment is good so that the maximum power level of the terminal is not required or the terminal in which the reception environment is poor and the correspondence of the maximum power level is required.

Accordingly, the present invention differentially applies a transmission power increase value by adding or subtracting a predetermined value to the Pmean_up in consideration of the reception environment of each terminal. Specifically, since the reception environment of each terminal can be known through the signal-to-interference ratio (SIR) received by the base station, the transmission power rise value corresponding to the SIR of each terminal is differentially applied (S307). Through this, a terminal with a poor reception environment has a relatively high transmit power rise value, and a terminal with a relatively good reception environment has a relatively low transmit power rise value.

When the transmission power increase value to be applied for each terminal is determined based on the SIR value of each terminal, the base station transmits the transmission power rise value information to each terminal through the traffic channel. Subsequently, each terminal connected to the base station receives the transmission power rise value information and increases the maximum power level stored in the RASRAM of the terminal by the transmission power rise value (S308).

On the other hand, as a result of comparing the total sum P of the received powers with the threshold received power Pth that the base station can receive (S305), if the total sum P of the received powers is greater than the threshold received power Pth, as described above, Likewise, there is no room to increase the transmission power of the mobile communication terminal, so the maximum power level of each mobile communication terminal must be maintained or lowered.

In maintaining or decreasing the maximum power level of the terminal, the maximum power level of each terminal must maintain a power level above a certain level. That is, the minimum maximum power level should be secured for the minimum call quality or call connection (S309). Therefore, when the total power P of the received power is greater than the threshold received power Pth, when the maximum power level of the terminal corresponds to the minimum maximum power level, the terminal maintains the set maximum power level as it is. . On the other hand, if the maximum power level of the terminal is greater than the minimum maximum power level means that there is room for the transmission power can be lowered by the difference, the lowering of the maximum power level may be performed by the following predetermined procedure.

The method of lowering the maximum power level (S310) of the terminal may use two methods. The first method is to uniformly lower the maximum power level of each terminal by a predetermined value, for example, 1 or 2 dBm, for all terminals connected to the corresponding base station, and the second method is as applied in the process of increasing the maximum power level. The differential application method is used. In addition to the above two methods, a method of selectively lowering the maximum power level by a predetermined value, for example, by 1 or 2 dBm, may be applied to a specific terminal having a very good reception environment.

The second method considers the reception environment of each terminal, and differentially applies the transmission power drop value according to the reception environment. Specifically, similarly to the process of increasing the maximum power level, the average possible falling value Pmean_down of the transmission power of each terminal as shown in Equation 2 below is obtained.

Pmean_down = (P-Pth) / N

Where Pth is the threshold received power, P is the sum of received power, and N is the total number of terminals connected to the base station.

Then, considering the SIR of each terminal connected to the base station, the transmission power drop value is determined by adding or subtracting a predetermined value to the Pmean_down value, and the base station transmits the differential transmission power drop value information to each terminal to the traffic channel. Send it through. Each terminal connected to the base station receives the transmission power drop value information and lowers the maximum power level stored in the terminal's RASRAM by the transmission power drop value. Of course, even at this time, the minimum maximum power level must be guaranteed.

The power control method of the mobile communication system according to the present invention has the following effects.

In consideration of the noise margin of the base station, the sum of the received power of the base station, the critical received power, and the like, the maximum power level of the terminal connected to the base station may be increased or decreased depending on the receiving environment of the terminal. Stable coverage of call connection and call quality can be achieved.

Claims (5)

In the power control method of the mobile communication system for controlling the power level between the mobile communication terminal and the base station, Comparing the signal-to-interference ratio (measurement SIR) and the target signal-to-interference ratio (Target SIR) of the channel signal transmitted from the mobile communication terminal to the base station; If the <measurement SIR> is less than <Target SIR>, comparing a total P of received powers received by the base station with a threshold received power Pth that the base station can accommodate; If the sum P of the received powers is less than the threshold received power Pth, the difference Pth-P between the threshold received power Pth and the sum P of the received powers Pth-P of the terminal connected to the corresponding base station is determined. A value ((Pth-P) / N) divided by the total number (N) is used as a reference transmission power increase value, and a predetermined value is subtracted or added from the reference transmission power rise value in consideration of <measurement SIR> of each terminal. And applying each of the differential transmission power rise values to each terminal to increase the maximum power level of each terminal by the transmission power rise value. The mobile communication system of claim 1, wherein a transmission power increase value applied to a terminal having a relatively low measurement SIR is higher than a transmission power rise value applied to a terminal having a relatively high measurement SIR. Power control method. The method according to claim 1, wherein the sum of received power (P) received by the base station is compared with the threshold received power (Pth) that the base station can accommodate, and the sum of received power (P) is the threshold received power (Pth). Is greater than, Reference transmission based on (P-Pth) / N obtained by dividing the difference (P-Pth) between the sum of received power (P) and the threshold received power (Pth) by the total number (N) of terminals connected to the base station. It is assumed that the power drop value is determined by subtracting or adding a predetermined value from the reference transmission power drop value in consideration of the <measurement SIR> of each terminal to apply the differential transmission power drop value to each terminal to maximize each terminal. And decreasing a power level by the transmission power falling value. The method according to claim 1, wherein the sum of received power (P) received by the base station is compared with the threshold received power (Pth) that the base station can accommodate, and the sum of received power (P) is the threshold received power (Pth). Is greater than, A method for controlling power of a mobile communication system, characterized in that the maximum power level of each terminal is lowered by 1 to 2 dBm uniformly with respect to all terminals connected to the base station. The mobile terminal of claim 4, wherein the maximum power level is selectively lowered by 1 to 1 dBm for a terminal having a relatively high <measurement SIR> in consideration of the <measurement SIR> of each terminal connected to the corresponding base station. Power control method of communication system.

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