KR100746998B1 - Apparatus and Method for Controlling Transmission Power in Orthogonal Frequency Division Multiplexing System - Google Patents

Abstract

The present invention relates to a transmission power control apparatus and method in an orthogonal frequency division multiplexing system.

In the present invention, the transmission power control apparatus configures a path for controlling the transmission power of the terminal device according to the power of the signal received at the terminal device receiving end, and in addition, controls the transmission gain according to the number of subchannels, According to the configuration, the power level may be adjusted so that the power density of the subchannel used by the terminal device can be controlled.

Accordingly, the transmission power control apparatus may determine whether to use the power concentrating function according to the location of the terminal apparatus, and accordingly, may control the transmission power of the terminal apparatus according to the distance and environment of the terminal apparatus and the base station apparatus.

According to the present invention, it is possible to effectively configure a transmission power control unit of a terminal device for a communication system using an orthogonal frequency division multiplexing scheme to expect a power concentrating effect of resolving an imbalance in transmission power of an uplink and a downlink.

Orthogonal Frequency Division Multiplexing System, transmit power, digital transmit power controller

Description

Apparatus and Method for Controlling Transmission Power in Orthogonal Frequency Division Multiplexing System

1 is a block diagram showing an internal configuration of a conventional transmission power control apparatus.

2 is a diagram illustrating cell coverage of a base station apparatus and a terminal apparatus according to uplink downlink power imbalance in an orthogonal frequency division multiplexing system using a subchannel.

3 is a block diagram illustrating an internal configuration of a transmission power control apparatus in an orthogonal frequency division multiplexing system according to an embodiment of the present invention.

4 is a block diagram illustrating an internal configuration of a control unit in a transmission power control apparatus according to an embodiment of the present invention.

5 is a flowchart illustrating a transmission power control method in an orthogonal frequency division multiplexing system according to an embodiment of the present invention.

The present invention relates to a transmission power control apparatus and method in an orthogonal frequency division multiplexing system, and more particularly, to control the gain of a transmission signal according to the number of subchannels, and the power level of the transmission signal that changes according to the number of subchannels. The present invention relates to a transmission power control apparatus and method for controlling transmission power of a terminal device.

In the code division multiplexing system, since multiple communications share the same frequency, there is a problem (perspective problem) of equalizing the strength of the interference wave (communication wave of another station) and the desired wave at the receiving end (perspective problem). This is severe in base station reception which simultaneously receives radio waves from multiple stations in the network.

In a code division multiplexing system, a plurality of channels use the same frequency, and the signal reception power (desired wave power) in a specific channel becomes interference wave power and serves to interfere with other channels. Therefore, when the desired wave power is more than a predetermined value in the uplink transmitted from the mobile station to the base station, the interference wave power can be increased to reduce the capacity of the channel. In order to prevent this, it is essential to strictly control the transmission power of the mobile station.

The transmission power control method includes open loop control performed on the basis of the reception level of the mobile station and closed loop control of feedback level information received from the base station from the base station to the mobile station as a control signal.

As a transmission power control apparatus using such a code division multiplexing scheme, Patent Publication No. 1999-72436 entitled 'Transmission power control apparatus and method and wireless communication apparatus and method' (1999.9.27) is described below. 1 is a block diagram showing an internal configuration of a conventional transmission power control device.

The prior art transmission power control apparatus includes a portion for calculating desired wave reception power from a received signal, a portion for storing received power, a portion for storing past transmission power, and a control signal periodically included in the received signal. It has a part to demodulate and a part which determines a transmission power setting value, and uses the system of determining the transmission power value using the past transmission power, desired wave reception power, and a control signal.

This method simply determines the transmission power based on the value received from the base station apparatus and the past transmission power value. That is, the terminal device power control method of the existing communication system adopts a method of simply controlling the transmission power of the terminal device according to the signal power received at the receiving end of the terminal device.

This method is not suitable in a communication system using an orthogonal frequency division multiplexing method using subchannels.

In the orthogonal frequency division multiplexing system using subchannels, in order to maintain the same link state in spite of a transmission power imbalance between a base station apparatus transmitting a relatively small power compared to a base station apparatus and a base station apparatus transmitting a high power compared to the terminal apparatus. It is designed to form a subchannel by binding a certain number of subcarriers to a transmission signal and to form a channel band by binding a certain number of subchannels.

By using such a subchannel, even if a terminal apparatus transmits a signal with the same transmission power in the same channel band, the power density of data actually transmitted varies according to the number of subchannels occupied by the transmitting signal.

Accordingly, since the conventional transmission power control apparatus shown in FIG. 1 cannot extract the power gain value due to the number of subchannels that can be changed instantaneously, the power concentration can be changed according to the number of subchannels used. There is a problem that can not implement the effect.

In order to solve such a problem, the present invention can control the gain of the transmission signal according to the number of subchannels, and transmit power control in an orthogonal frequency division multiplexing system controlling the power level of the transmission signal that varies according to the number of subchannels. To provide an apparatus and method.

In accordance with one aspect of the present invention, an apparatus for controlling transmission power in an orthogonal frequency division multiplexing system includes a digital transmitter for transmitting a baseband transmission signal; A first digital transmit power controller which receives information on the number of subchannels from the digital transmitter and controls a gain of a transmission signal that varies according to the number of subchannels; An analog modulator for modulating a baseband transmit signal into a signal in an intermediate frequency band; A first band pass filter for canceling intermodulation signals and higher order mode signals generated from the analog modulator; A first analog transmit power controller for compensating for the power level of the varying transmit signal; And a control unit controlling the first digital transmit power controller and the first analog transmit power controller to control the power density of the subchannels according to the number of subchannels.

According to another aspect of the present invention, a method for controlling transmission power of a terminal device in an orthogonal frequency division multiplexing system includes (a) receiving information on the number of subchannels from a digital transmitter and generating and transmitting a gain control signal according to subchannel coefficients. Doing; (b) receiving transmission timing information from the digital receiver and determining whether to use the power concentrating function according to the terminal location; (c) when determining the use of the power concentrating function in step (b), generating and transmitting gain variation information according to the use of the power concentrating function; And (d) controlling the transmission power of the terminal device according to the amount of power received from the digital receiver.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

In addition, when a part is said to "include" a certain component, it means that it may further include other components, without excluding other components unless otherwise stated.

An apparatus and method for controlling transmission power in an orthogonal frequency division multiplexing system according to an embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

2 is a diagram illustrating cell coverage of a base station apparatus and a terminal apparatus according to uplink downlink power imbalance in an orthogonal frequency division multiplexing system using a subchannel.

In FIG. 2, region 1 represents cell coverage by transmission power of the base station apparatus, and region 2 represents cell coverage by transmission power of the terminal apparatus.

Since the base station apparatus can be fabricated with a sufficiently large transmission power, it can be fabricated to cover region 1, which is required cell coverage. However, a terminal device with a limited power consumption may cover up to area 2 relatively smaller than area 1.

When the terminal device is located between the area 2 and the area 1 due to this power imbalance, uplink cannot be formed and communication between the base station device and the terminal device is impossible.

In order to solve the link disconnection problem caused by the power imbalance, the transmission power control apparatus of the embodiment of the present invention reduces the number of subchannels used by the terminal apparatus when the terminal apparatus exceeds the area 2, and uses the same transmission power. By increasing the power density of the subchannel, the power concentration effect to solve the link disconnection problem is realized.

3 is a block diagram illustrating an internal configuration of a transmission power control apparatus in an orthogonal frequency division multiplexing system according to an embodiment of the present invention.

According to an embodiment of the present invention, a transmission power control apparatus includes a digital transmitter 300, a first digital transmission power controller 310, an analog modulator 320, a first band pass filter 330, and a first analog transmission power controller ( 340, the frequency mixer 350, the second band pass filter 360, the second analog transmit power controller 370, the power amplifier 380, the controller 400, and the like.

The digital transmitter 300 is a device for generating a baseband transmission signal, and outputs a transmission signal to the first digital transmission power controller according to the number of subchannels used when transmitting a signal from the terminal device.

The first digital transmit power controller 310 is a device for controlling the gain of the transmission signal according to the number of subchannels used by the terminal device. The first digital transmit power controller 310 receives information on the number of subchannels used by the terminal device from the digital transmitter 300. The digital gain is controlled to output a constant level of output signal to a transmission input signal that varies according to the number of subchannels.

The analog modulator 320 is a device for modulating a baseband transmission signal into a signal of an intermediate frequency band. The analog modulator 320 modulates an output signal of the first digital transmission power controller 310 into an analog signal of an intermediate frequency band to filter the first band pass. Output to (330).

The first band pass filter 330 functions to remove intermodulation signals and higher order mode signals generated from the analog modulator 320.

The first analog transmission power controller 340 is a device for compensating the power level of a transmission signal that is varied from the digital power variable device. The first analog transmission power controller 340 compensates for the power level of the transmission signal whose level varies in accordance with the number of subchannels. Power density can be controlled.

The frequency mixer 350 converts the intermediate frequency signal into a signal of a transmission band and outputs the signal to the second band pass filter 360.

The second band pass filter 360 functions to remove intermodulation signals and higher order mode signals generated from the frequency mixer 350.

The second analog transmission power controller 370 is a device for controlling the transmission signal power of the terminal device based on the signal level received from the base station device, and the function of controlling the final transmission power of the terminal device according to the power received from the base station device. Do it.

The power amplifier 380 amplifies the transmission band signal output from the second analog transmission power controller 370 and transmits the signal to the base station apparatus.

The controller 400 controls the transmission power of the terminal device according to the power of the signal received at the receiving end of the terminal device. In addition, the controller 400 receives information on the number of subchannels to control the gain of the transmission signal, and thereby controls the power level of the variable transmission signal to change the power density according to the number of subchannels. .

Hereinafter, an internal configuration of the control unit 400 of the transmission power control apparatus in FIG. 4 will be described in detail.

4 is a block diagram illustrating an internal configuration of a control unit in a transmission power control apparatus according to an embodiment of the present invention.

The control unit 400 according to an embodiment of the present invention may include a first memory access block 410, a first memory unit 420, a first gain control signal generator 430, a second memory access block 440, and a first memory access block 440. And a second memory unit 450, a second gain control signal generator 460, a third memory access block 470, a third memory unit 480, and a third gain control signal generator 490.

The first digital gain control unit includes a first memory access block 410, a first memory unit 420, and a first gain control signal generator 430.

The first analog gain control unit includes a second memory access block 440, a second memory unit 450, and a second gain control signal generator 460.

The second analog gain control unit includes a third memory access block 470, a third memory unit 480, and a third gain control signal generator 490.

The first memory access block 410 receives information on the number of subchannels used by the terminal device from the digital transmitter 300, calculates and stores a gain change amount according to the number of subchannels, and stores the calculated gain change amount in the first memory. Transmit to unit 420.

The first memory unit 420 stores a gain change amount according to the number of subchannels, and transmits gain change amount information according to the stored number of subchannels to the first gain control signal generator 430.

The first gain control signal generator 430 receives the gain variation information according to the number of subchannels of the first memory unit 420, and generates a gain control signal according to the number of subchannels using the received gain variation information. Transmit to the first digital transmit power controller 310.

The second memory access block 440 receives information on the amount of power received by the terminal device from the digital receiver 500, calculates and stores gain change information according to the amount of power, and stores the gain change information according to the calculated amount of power. Transfer to the memory unit 450.

The second memory unit 450 stores gain change information according to the amount of power received by the terminal device, and transmits the gain change information according to the stored amount of power to the second gain control signal generator 460.

The second gain control signal generator 460 receives the gain change information according to the power amount of the second memory unit 450 and generates a gain control signal according to the received power amount using the received gain change information to generate the second analog signal. Transmit to transmit power controller 370.

The third memory access block 470 receives the transmission timing information of the terminal device extracted and corrected in the initial access process between the terminal device and the base station device from the digital receiver 510, and uses the transmission timing information to transmit the power concentration function. It determines whether it is implemented, and transmits the gain change amount information according to whether the power concentrating function is implemented to the third memory unit 480. Here, as shown in FIG. 2, the power concentrating function reduces the number of subchannels used by the terminal device when the terminal device crosses the region 2 and increases the power density of the subchannels used at the same transmission power. It means the function to solve the problem of link disconnection.

Accordingly, the third memory access block 470 determines whether to use the power concentrating function according to the position of the terminal using transmission timing information of the terminal device, and obtains the gain change amount information (voltage information) according to whether the power concentrating function is used. The difference is generated, and the generated gain change amount information is transmitted to the third memory unit 480.

The third memory unit 480 stores gain variation information for determining whether to implement the power concentrating function, and transmits the stored gain variation information to the third gain control signal generator 490.

The third gain control signal generator 490 receives the gain change amount information of the third memory unit 480 and generates a gain control signal based on whether the power concentrating function is implemented using the received gain change amount information. Transmit to the analog transmit power controller 340.

In the exemplary embodiment of the present invention, when the terminal apparatus is located in an area requiring the power concentrating function, the transmission power concentrating function may be controlled by controlling the gain of the first analog transmit power controller 340.

In the embodiment of the present invention, the transmission power control apparatus controls the gain of the first analog transmission power controller 340 when the terminal apparatus is located in a region adjacent to the base station apparatus and does not require the transmission power concentrating function. The transmit power concentration function may not be implemented.

In addition, the apparatus for controlling transmission power improves the problem of signal-to-noise ratio reduction of a transmission signal that may occur when the power concentrating function is implemented only by the first analog transmission power controller 340 by configuring the first digital transmission power controller 310. can do.

Hereinafter, a transmission power control method in an orthogonal frequency division multiplexing system will be described in detail with reference to FIG. 5.

The controller 400 receives information on the number of subchannels used by the terminal device from the digital transmitter 300 and calculates and stores a gain change amount according to the number of subchannels using the information on the number of subchannels (S500). .

The controller 400 generates a gain control signal according to the number of subchannels using the gain change amount information corresponding to the number of subchannels, and transmits the generated gain control signal to the first digital transmit power controller 310 (S502).

The controller 400 receives transmission timing information of the terminal device extracted and corrected in the initial access process between the terminal device and the base station device from the digital receiver 510 (S504). Subsequently, the controller 400 determines whether to use the power concentrating function according to the terminal location using the transmission timing information of the terminal device (S506).

As a result of the determination in step S506, when the controller 400 determines to use the power concentrating function in the terminal device (that is, out of the cell coverage area due to the transmission power of the terminal device), the controller 400 uses the power concentrating function. The gain change amount information (voltage information) is generated, and the gain control signal according to the use of the power concentration function is generated using the generated gain change amount information, and is transmitted to the first analog transmit power controller 340 (S508).

The control unit 400 receives information on the amount of power received from the base station apparatus by the terminal device from the digital receiver 500, calculates gain change information according to the amount of power, and uses the gain change information according to the calculated amount of power according to the amount of power. A gain control signal is generated and transmitted to the second analog transmit power controller 370 (S510).

As a result of the determination in step S506, when the controller 400 determines not to use the power concentrating function for the terminal device (that is, located in the cell coverage area by the transmission power of the terminal device), the controller 400 proceeds to step S550. Proceeding by generating a gain control signal according to the amount of power received to control the transmission power of the terminal device.

As shown in FIG. 5, when the control unit 400 controls the transmission power through steps S530, S540, and S550, a power concentration function may be used, and when the transmission power is controlled through steps S530 and S550. In this way, the transmission power is controlled according to the amount of power received in the conventional manner without using the power concentration function.

Here, as shown in FIG. 2, the power concentrating function reduces the number of subchannels used by the terminal device when the terminal device crosses the region 2 and increases the power density of the subchannels used at the same transmission power. It means the function to solve the problem of link disconnection.

Accordingly, the transmission power control device determines whether to use the power concentrating function according to the location of the terminal device, and accordingly, can control the transmission power of the terminal device according to the distance and environment of the terminal device and the base station device.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

According to the above-described configuration, the present invention can expect a power concentrating effect of effectively configuring a transmission power control unit of a terminal apparatus for a communication system using an orthogonal frequency division multiplexing scheme to solve an imbalance in transmission power of an uplink and a downlink. have.

According to the present invention, even when using a small number of subchannels, an effect of not deteriorating a characteristic of a signal-to-noise ratio of a transmission signal can be expected.

The present invention can use the configuration and control algorithm of the second transmission power controller that has been used for the conventional transmission power control can be expected to have the advantage that there is no difficulty in the separate design and configuration for the RF block.

Claims (11)

A transmission power control apparatus in an orthogonal frequency division multiplexing system, A digital transmitter for transmitting a baseband transmission signal; A first digital transmit power controller which receives information on the number of subchannels from the digital transmitter and controls a gain of a transmission signal that varies according to the number of subchannels; An analog modulator for modulating the baseband transmit signal into a signal in an intermediate frequency band; A first band pass filter for removing intermodulated signals and higher order mode signals generated from the analog modulator; A first analog transmit power controller for compensating for the power level of the variable transmit signal; And A control unit controlling the first digital transmit power controller and the first analog transmit power controller to control the power density of the subchannels according to the number of subchannels Transmission power control apparatus comprising a. The method of claim 1, wherein the control unit, When the terminal device is located in an area where a power concentrating function is required, the gain of the first analog transmit power controller is controlled to implement the power concentrating function, and the terminal device is located in an area where the power concentrating function is not required. In this case, the transmission power control apparatus characterized in that the power concentration function is not implemented by controlling the gain of the first analog transmission power controller. The method of claim 1, wherein the control unit, A first digital gain controller which receives information on the number of subchannels from the digital transmitter and generates a digital gain control signal according to the number of subchannels; And A second analog gain controller which receives the transmission timing information from the digital receiver and generates a gain control signal according to whether to implement a power concentrating function Transmission power control apparatus comprising a. The method of claim 3, wherein the first digital gain control unit, A first memory access block receiving information on the number of subchannels from the digital transmitter and calculating gain variation information according to the number of subchannels; A first memory unit configured to receive and store gain variation information according to the number of subchannels from the first memory access block; And A first gain control signal generator which extracts the gain variation information from the first memory unit, generates a digital gain control signal according to the number of subchannels, and transmits the digital gain control signal to the first digital transmit power controller Transmission power control apparatus comprising a. The method of claim 3, wherein The control unit further includes a first analog gain control unit for generating a gain control signal according to the amount of power. The method of claim 5, wherein the first analog gain control unit, A second memory access block receiving power amount information from a digital receiver and calculating gain change information according to power amount; A second memory unit configured to receive and store gain change information according to the amount of power from the second memory access block; And A second gain control signal generator which extracts the gain change information from the second memory unit, generates a gain control signal according to the amount of power, and transmits the gain control signal to a second analog transmission power controller; Transmission power control apparatus comprising a. The method of claim 3, wherein the second analog gain control unit, A third memory access block receiving the transmission timing information of the terminal device from a digital receiver, determining whether to use the power concentrating function according to the terminal position, and generating and transmitting gain variation information according to whether the power concentrating function is used; A third memory unit configured to receive, store, and output gain variation information according to whether to use the power concentrating function from the third memory access block; And A third gain control signal generator which extracts the gain variation information from the third memory unit, generates a gain control signal according to whether the power concentrating function is used, and transmits the gain control signal to the first analog transmit power controller Transmission power control apparatus comprising a. According to claim 1, The transmission power control device, A frequency mixer for converting a signal of an intermediate frequency band, which is an output signal of the first analog transmission power controller, into a signal of a transmission band; A second band pass filter for removing intermodulation signals and higher order mode signals generated from the frequency mixer; A second analog transmit power controller for controlling the final transmit power of the terminal device according to the power received from the base station device; And A power amplifier for amplifying a signal of a transmission band output from the second analog transmission power controller Transmission power control apparatus further comprising. The method of claim 2 or 3, The power concentrating function reduces the number of the subchannels and increases the power density of the subchannels. In the method for controlling the transmission power of a terminal device in an orthogonal frequency division multiplexing system, (a) receiving information on the number of subchannels from a digital transmitter and generating and transmitting a gain control signal according to subchannel coefficients; (b) receiving transmission timing information from the digital receiver and determining whether to use the power concentrating function according to the terminal location; (c) when determining the use of the power concentrating function in step (b), generating and transmitting gain variation information according to the use of the power concentrating function; And (d) controlling the transmission power of the terminal device according to the amount of power received from the digital receiver; Transmission power control method comprising a. The method of claim 10, If it is determined in step (b) that the power concentrating function is not to be used, controlling the transmission power of the terminal device according to the amount of power received from the digital receiver.

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