KR20100062709A - Method and device for controlling uplink power in ofdm wideband mobile communication systems - Google Patents

Abstract

PURPOSE: An uplink power control method of an OFDM(Orthogonal Frequency Division Multiplexing) broadband mobile communication system and a device thereof are provided to prevent deterioration of a transmission signal quality of a terminal according to excessive difference of an inter-channel transmission power by keeping difference of a transmission power of an uplink control channel and a transmission power of a uplink data traffic channel below a predetermined level. CONSTITUTION: A control channel power controller(150) controls a transmission power level of a uplink control channel. A data traffic channel power controller(160) controls a transmission power level of a uplink data traffic channel. In order that difference of a transmission power of the uplink control channel and a transmission power of the uplink data traffic channel is kept below a predetermined threshold value, the control channel power controller and the data traffic channel power controller controls the transmission power levels.

Description

TECHNICAL AND DEVICE FOR CONTROLLING UPLINK POWER IN OFDM WIDEBAND MOBILE COMMUNICATION SYSTEMS

The present invention relates to a mobile communication system, and more particularly, to a method and apparatus for controlling uplink power of a broadband mobile communication system using an orthogonal frequency division access.

Mobile communication services are evolving from voice-oriented services to data-oriented services. 3G mobile communication systems such as cdma2000 1xEV-DO (Evolution Data Only) / cdma2000 1xEV-DV (Evolution Data & Voice) or UMTS Universal Mobile Telecommunications System High Speed Packet Access (HSPA) to provide high-speed data communication services are fundamental. Compared to the Code Division Multiple Access (Code Division Multiple Access) scheme, the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), the fourth generation broadband mobile communication air interface standard, is used for Orthogonal Frequency Division. Multiplexing (OFDM) scheme is adopted.

The OFDM scheme is a modulation scheme in which a high-speed transmission signal is multiplexed into multiple narrowband carriers orthogonal to each other on a time axis to transmit and receive. The OFDM method uses a plurality of carriers having mutual orthogonality, and thus has high frequency utilization efficiency. In addition, according to the OFDM scheme, since a process of modulating / demodulating a plurality of carriers in a transmitter / receiver can be implemented at high speed using inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT), respectively, It is especially suitable for the data transmission of.

In the mobile communication system using the OFDM scheme, the strength of the uplink physical channel signals received from the terminals in the cell within a predetermined range for each physical channel in order to provide services to a large number of terminals in a limited frequency band. It is preferred to be controlled to be similar to This is because when a sudden change in transmission power occurs in a signal transmitted from a terminal, quality degradation of a signal transmitted from the terminal may occur, and thus a loss rate of an uplink data packet may increase. Therefore, in the OFDM system, it is required to control the power variation of the uplink signal for each physical channel so as not to deviate from an appropriate range.

In an OFDM system supporting wideband, the uplink includes a control channel for transmitting a control signal and a data traffic channel for transmitting data traffic. The terminal transmits only a control signal through a control channel when there is no data traffic to be transmitted to the base station for a predetermined unit time, and transmits a data signal through the data traffic channel together with a control signal through the control channel when there is data traffic to be transmitted. . In relation to the power control of the uplink signal described above, it is known that in OFDM systems supporting broadband, it is advantageous to independently control the transmission power of the uplink control channel and the uplink data traffic channel in terms of utilization efficiency of frequency resources. . Accordingly, the LTE (Long Term Evolution) standard, which is the current 4th generation broadband mobile communication air interface standard, specifies to separately control the control channel and the data traffic channel with respect to the control of the transmission power of the terminal. According to the current LTE specification, the base station receives a Signal to Interference and Noise Ratio (SINR) of a signal received by an uplink control channel and a SINR of a signal received by an uplink data traffic channel. Are respectively measured, and the SINR measured for each channel is compared with a threshold set for each channel to independently generate information for power control of each channel and transmit it to the terminal. Accordingly, the terminal determines transmission power of the uplink control channel and the uplink data traffic channel, respectively, using the power control information received from the base station through the downlink. That is, since the power control information transmitted from the base station to the terminal is independent of each of the control channel and the data traffic channel, the power level transmitted by the terminal through the control channel and the data traffic channel is also independently controlled for each channel.

However, when a downlink resource for use by the base station to transmit power control information to the terminal is temporarily depleted, when the radio channel environment is suddenly changed, when the power control information transmitted through the downlink is lost, or constant When data traffic with burst characteristics such that data traffic is continuously transmitted during a time interval or no data traffic is transmitted at all during a time interval is transmitted, for example, between the transmission power of the control channel and the transmission power of the data traffic channel. Large separations can occur. In fact, when the power level variation of each channel of the signal transmitted by the terminal is severe, more than 40dB may occur. As such, when the separation between the transmission power between the uplink control channel and the data traffic channel becomes abnormally large, a quality degradation of the terminal transmission signal occurs, a degradation of the uplink SINR measurement accuracy of the base station, and thus an incorrect uplink. Many problems occur, such as power control or uplink data packet loss.

Disclosure of Invention An object of the present invention is to provide a method for controlling an uplink power of a control channel and a data channel in an OFDM broadband mobile communication system to compensate for independent control of each channel so that a difference in power levels between two channels does not exceed a predetermined range. It is to provide a device.

According to an embodiment of the present invention, there is provided a terminal device including a control channel power control unit for controlling a transmission power level of an uplink control channel, and a data traffic channel power control unit for controlling a transmission power level of an uplink data traffic channel. do. According to an embodiment, the control channel power control unit and the data traffic channel power control unit are configured such that a difference between the transmission power level of the uplink control channel and the transmission power level of the uplink data traffic channel is equal to or less than a predetermined threshold. Outgoing power levels can be controlled.

According to embodiments of the present invention, the difference between the outgoing power of the uplink control channel and the outgoing power of the data traffic channel in the OFDM broadband mobile communication system is kept below a certain level, resulting in excessive difference in outgoing power between channels The deterioration of the quality of the terminal transmission signal can be prevented.

Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention. However, in the following description, when there is a risk of unnecessarily obscuring the gist of the present invention, a detailed description of well-known functions and configurations will be omitted. In addition, it should be understood that the following embodiments are merely intended to illustrate the present invention, but not to limit the present invention.

1 illustrates a structure of a user terminal that can be used in a mobile communication system according to an embodiment of the present invention. As shown in FIG. 1, the terminal 100 according to an embodiment may include a receiver 110 that receives a signal transmitted from a communication device such as a base station (not shown). According to an embodiment, the signal received through the receiver 110 may be a signal message (for example, a call setup message or a handover message) sent by a base station to a specific terminal and / or a broadcast message sent by the base station to all terminals in a cell. It may include.

The terminal 100 may further include a demodulator 120 and a processor 130. According to an embodiment, the demodulator 120 demodulates the signal received by the receiver 110 in an appropriate format. Then, the processor 130 may receive the appropriately demodulated signal from the demodulator 120 to analyze desired information from the corresponding signal, or generate signal information to be transmitted to another communication device such as a base station. According to an embodiment, the processor 130 may perform a function of controlling various components included in the terminal 100. The processor 130 may also generate and process a signal that the terminal 100 intends to transmit.

The terminal 100 may further include a memory 140. According to an embodiment of the present disclosure, the memory 140 may be connected to the processor 130 and store various types of information analyzed by the processor 130. In particular, the memory 140 may store information regarding power control of an uplink signal to be transmitted by the terminal 100. In such a case, the information about power control of the uplink signal to be transmitted by the terminal 100 stored in the memory 140 may be based on information received from the base station. According to one embodiment, the base station (not shown), the control channel for the terminal 100 using the signal-to-noise and interference ratio (SINR) of the uplink control channel and data traffic channel from the terminal 100 The power control information and the data traffic channel power control information may be generated and transmitted to the terminal 100.

The terminal 100 may further include a control channel power control unit 150 and a data traffic channel power control unit 160. The control channel power control unit 150 and the data traffic channel power control unit 160 may adjust the transmission signal generated and processed by the processor 130, that is, the control signal and the data traffic signal, respectively, to an appropriate power level. According to an embodiment, the control channel power control unit 150 may control the power level of the uplink control channel signal to be transmitted from the terminal 100 to the base station, and the data traffic channel power control unit 160 may control the terminal ( In step 100), power level control on the uplink data traffic channel signal to be transmitted to the base station may be performed. As described above, according to an embodiment, the memory 140 may store information about power control of an uplink signal to be transmitted by the terminal 100, and the control channel power controller 150 and the data traffic channel power controller Each of the 160 may perform power level control of each channel using information stored in the memory 140.

According to an embodiment, the control channel power control unit 150 and the data traffic channel power control unit 160 may be configured to communicate with each other. Control of the power level of the uplink control channel signal and control of the power level of the data traffic channel in the terminal 100 should be made so that the difference between the power levels of both channels does not deviate from a predetermined range according to the principles of the present invention described later. In this case, the control channel power control unit 150 and the data traffic channel power control unit 160 may achieve control of such a power level through communication with each other. In FIG. 1, although the control channel power control unit 150 and the data traffic channel power control unit 160 are illustrated as separate components that can communicate with each other, according to another embodiment of the present invention, they are combined as one component. It should be appreciated that it may be used.

According to an embodiment of the present invention, the control channel power control unit 150 and the data traffic channel power control unit 160 compare the power levels of the outgoing signals of each channel to each other so that the difference between the two does not exceed a predetermined threshold value. Can be controlled. For example, when it is determined that the difference between the power levels of both channels exceeds a predetermined threshold, the power level of the signal with the higher power level of both channels is adjusted so that the difference between the two power levels does not become larger than the predetermined threshold. Can be adjusted.

According to one embodiment of the invention, the predetermined threshold value used for the comparison of the difference between the outgoing power levels of the control channel and the data traffic channel is a signal received from the base station, for example a call setup message or hand for the terminal 100. It may be determined based on an over message or other broadcast message. According to another embodiment, the predetermined threshold value may be a value set inside the terminal 100. According to an embodiment of the present invention, the predetermined threshold may be '0', in which case, the terminal 100 may receive only power control information for the control channel and use it for data traffic channel power control. .

Referring to FIG. 1, the terminal 100 may further include a modulator 170 and a transmitter 180. The modulator 170 may modulate the transmission signal to be transmitted by the terminal 100 in an appropriate format. The signal modulated by the modulator 170 may be transmitted to the base station by the transmitter 180.

The structure of the terminal 100 shown in FIG. 1 is exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible.

2 is a flowchart of a method of controlling uplink power in a terminal 100 according to an embodiment of the present invention. Hereinafter, an embodiment of a method of performing power control for each channel of an uplink in an OFDM broadband mobile communication system will be described with reference to FIG. 2. In the following embodiments, P _a (n) and P _b (n) represent the power level of the control channel signal and the power level of the data traffic channel signal at the nth Transmission Time Interval (TTI), respectively. P _{diff_thresh} represents a threshold that defines the maximum allowable difference between the power level of the control channel signal and the power level of the data traffic channel signal.

As shown in FIG. 2, in step 205, the terminal 100 may determine whether power control information for the control channel has been received from the base station in any n-th TTI. If it is determined in step 205 that the terminal 100 has not received power control information for the control channel, the terminal 100 transfers the transmission power level of the control channel signal in the nth transmission time interval (n−). First, it can be set similarly to the case of the transmission time interval (step 210). Then, the terminal 100 may determine whether the power control information for the data traffic channel is received from the base station (step 215).

If it is determined in step 215 that power control information for the data traffic channel has not been received, the terminal 100 transfers the transmission power level of the data traffic channel signal in the nth transmission time interval (n-1th). As in the case of the transmission time interval, it can be set (step 220). Then, the terminal 100 may compare the difference between the transmission power level of the control channel signal and the transmission power level of the data traffic channel signal (| P _a (n) -P _b (n) |) with a threshold value P _{diff_thresh} . (Step 225). If it is determined in step 225 that the difference between the outgoing power level of the control channel signal and the outgoing power level of the data traffic channel signal (| P _a (n) -P _b (n) |) is greater than the threshold value P _{diff_thresh} The output power level of the channel having the larger output power level among the control channel and the data traffic channel, and the sum of the output power value and the threshold value of the channel having the smaller output power level (min (P _a (n), P _b (n)) + P _{diff_thresh} ) (step 230). In step 225, the difference between the outgoing power level of the control channel signal and the outgoing power level of the data traffic channel signal (| P _a (n) -P _b (n) |) is less than or equal to the threshold value P _{diff_thresh} . If so, each outgoing power level of the control channel signal and the data traffic channel can be maintained as in the previous (n−1) th transmission time interval.

If it is determined in step 215 that the power control information for the data traffic channel has been received, the terminal 100 receives the predetermined power control information based on the received power control information of the data traffic channel signal in the nth transmission time interval. Update by the amount ΔP ₂ (step 235). Then, the terminal 100 compares the difference between the transmission power level of the control channel signal and the transmission power level of the data traffic channel signal (| P _a (n) -P _b (n) |) with a threshold value P _{diff_thresh} . May be step 240. If it is determined in step 240 that the difference between the outgoing power level of the control channel signal and the outgoing power level of the data traffic channel signal (| P _a (n) -P _b (n) |) is greater than the threshold P _{diff_thresh} In operation 245, the terminal 100 may adjust the transmission power level of the control channel signal by a predetermined amount ΔP ₂ as used for updating the transmission power level of the data traffic channel signal. In step 240, it is determined that the difference between the outgoing power level of the control channel signal and the outgoing power level of the data traffic channel signal (| P _a (n) -P _b (n) |) is less than or equal to the threshold value P _{diff_thresh} . In one case, the outgoing power level of the control channel signal can be maintained as in the previous (n−1) th transmission time interval.

If it is determined in step 205 that the terminal 100 has received the power control information for the control channel, the terminal 100 receives the power control information of the transmission power level of the control channel signal in the nth transmission time interval Can be updated by a predetermined amount ΔP ₁ based on (step 250). Then, the terminal 100 may determine whether power control information for the data traffic channel is received from the base station (step 255).

If it is determined in step 255 that the power control information for the data traffic channel has not been received, the terminal 100 transfers the transmission power level of the data traffic channel signal in the nth transmission time interval (n-1th). As in the case of the transmission time interval, it can be set (step 260). Then, the terminal 100 compares the difference between the outgoing power level of the updated control channel signal and the outgoing power level of the data traffic channel (| P _a (n) -P _b (n) |) with a threshold value P _{diff_thresh} . May be step 265. If it is determined in step 265 that the difference between the outgoing power level of the control channel signal and the outgoing power level of the data traffic channel signal (| P _a (n) -P _b (n) |) is greater than the threshold value P _{diff_thresh} In operation 270, the terminal 100 may adjust the transmission power level of the data traffic channel signal by a predetermined amount ΔP ₁ as used for updating the transmission power level of the control channel signal. In step 265, it is determined that the difference between the outgoing power level of the control channel signal and the outgoing power level of the data traffic channel signal (| P _a (n) -P _b (n) |) is less than or equal to the threshold value P _{diff_thresh} . In one case, the outgoing power level of the data traffic channel signal may be maintained as in the previous (n−1) th transmission time interval.

If it is determined in step 255 that the power control information for the data traffic channel has been received, the terminal 100 receives a predetermined amount based on the received power control information for the power level of the data traffic channel in the nth transmission time interval. It can be updated by [Delta] P ₂ (step 275). The procedure may then proceed to step 225.

Although various functional components have been described in the embodiments herein, the embodiments may be implemented in hardware, software, firmware, middleware, or a combination thereof, and may be used in a system, subsystem, component, or subcomponent thereof. Should know. When implemented in software, a component of the embodiments is an instruction / code segment for performing a required task. The program or code segment may be stored on a machine readable medium, such as a processor readable medium or a computer program product, or transmitted over a transmission medium or communication link by a computer data signal embodied in a carrier wave or a signal modulated by a carrier. have. Machine readable media or processor readable media may include any medium that can store or transmit information in a form readable and executable by a machine (eg, processor, computer, etc.).

Although the method and apparatus of the present invention have been described with reference to the embodiments illustrated in the drawings for clarity, this is merely illustrative, and various modifications and equivalent other embodiments of the present invention may be made by those skilled in the art. I understand that it is possible. Therefore, the true technical protection scope of the present invention should be defined by the following claims.

1 is a view showing the structure of a terminal that can be used in a mobile communication system according to an embodiment.

2 is a flowchart of an uplink power control method according to an embodiment.

Claims (12)

As a terminal device, A control channel power control unit for controlling a transmission power level of the uplink control channel, and A data traffic channel power control unit for controlling an outgoing power level of an uplink data traffic channel; The control channel power control unit and the data traffic channel power control unit control the outgoing power levels so that a difference between the outgoing power level of the uplink control channel and the outgoing power level of the uplink data traffic channel is equal to or less than a predetermined threshold. A terminal device in operation. The method of claim 1, The control channel power control unit and the data traffic channel power control unit may control the uplink control channel when the difference between the outgoing power level of the uplink control channel and the outgoing power level of the uplink data traffic channel exceeds the threshold. And adjust an output power level of a channel having a higher output power level among the uplink data traffic channels. The method of claim 1, And a receiver configured to receive control information for determining a transmission power level of the uplink control channel or control information for determining the transmission power level of the data traffic channel by a downlink signal. The method of claim 3, If the receiving unit receives only one of control information for determining the outgoing power level of the uplink control channel or control information for determining the outgoing power level of the uplink data traffic channel by the downlink signal, the control channel The power control unit and the data traffic channel power control unit update the transmission power level of one of the uplink control channel and the related one of the uplink data traffic channel based on the received control information, and update the uplink control channel and the uplink control channel. And if the difference between the outgoing power levels of the link data traffic channels exceeds the threshold, adjust the outgoing power level of the other other channel. The method of claim 3, The control channel power when the receiver receives both control information for determining the outgoing power level of the uplink control channel and control information for determining the outgoing power level of the uplink data traffic channel by the downlink signal; The control unit and the data traffic channel power control unit update the outgoing power levels of the uplink control channel and the uplink data traffic channel based on the received control information, and the uplink control channel and the uplink data traffic channel. And when the difference between the outgoing power levels of the exceeds the threshold value, the outgoing power level of the uplink control channel and the uplink data traffic channel, the outgoing power level of the higher channel. The method of claim 1, And a receiving unit which receives control information for determining the threshold value by a downlink signal. The method of claim 6, Control information for determining the threshold value is included in a call setup message received by the receiver by the downlink signal. The method of claim 6, The control information for determining the threshold value is included in a handover message received by the receiver by the downlink signal. The method of claim 6, The control information for determining the threshold value is included in a broadcast message received by the receiver by the downlink signal. The method of claim 1, The threshold value is a terminal device which is a preset value in the terminal device. The method of claim 1, The terminal device is used in a broadband mobile communication system using an Orthogonal Frequency Division Access (OFDM) scheme. A method of controlling uplink power in a broadband mobile communication system, Calculating a difference between the outgoing power level of the uplink control channel and the outgoing power level of the uplink data traffic channel; Comparing the calculated difference in power output levels of both channels with a predetermined threshold value, Adjusting a transmission power level of a channel having a higher transmission power level among the uplink control channel and the uplink data traffic channel when the difference between the calculated transmission power levels of both channels exceeds the threshold value. How to include.

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