KR20000001795A - Power control device and method for mobile communication system - Google Patents

Abstract

PURPOSE: A power control device for a mobile communication system is provided to control power while a traffic channel is off. CONSTITUTION: A power control device for a mobile communication system includes a base station and a mobile station. The base station has a transmission diversity function, generates a specific common channel signal for transmitting a traffic channel signal through a traffic-on antenna, and transmitting a reference value about a transmission power through a traffic-off antenna. The mobile station has a plurality of receivers according to transmission diversity. After the receivers store traffic power in case of a traffic-off, the mobile station detects a power variation of a common channel, calculates a virtual traffic power, generates virtual power control information according to the virtual traffic power, and transmits the virtual power control information to the base station through a backward link.

Description

Power control device and method for mobile communication system

The present invention relates to an apparatus and method for controlling power in a mobile communication system, and more particularly, to an apparatus and method for controlling power when a traffic channel is off.

In general, power control in a mobile communication system measures the power of a received signal according to the state of a radio link at a receiving side, and transmits the result to the transmitting side, and the transmitting side transmits the signal according to the receiving power control. Will increase or decrease the power. In order to control the transmit power of the base station in the mobile communication system, the mobile station measures a Signal to Interference Ratio (SIR) and compares it with a threshold to give a high or low result of the reverse channel to the base station. Report via power control bit. Then, the base station receiving the power control bit adjusts the power of the transmission signal by a predetermined step according to the received power control bit value. That is, in the forward link power control method of the mobile communication system, the mobile station measures the power of the base station transmission signal and reports the result to the base station, and the base station controls the power of the transmission signal according to the power control information of the mobile station. Closed Loop) method is used.

1 is a diagram illustrating a forward link power control process of a mobile communication system. Referring to FIG. 1, a signal transmitted from a base station as shown by 111 is delayed from 113 and received by a mobile station, and the mobile station measures power of the received signal. Thereafter, the mobile station generates a power control bit (PCB) according to the received power measurement result and transmits it to the base station as 115, and the base station receives the power control bit transmitted from the mobile station as 117 and then receives it. The power of the transmission signal is controlled as in 119 according to the value of the power control bit. As shown in FIG. 1, the power control is performed in units of a power control group (PCG), and the actual power is controlled by delaying one or more power control groups.

As described above, power control of the mobile communication system is performed once every time unit called a power control group. When the base station transmits a signal and the mobile station receives the signal, the mobile station measures the SIR of the received signal, compares the measured value with a threshold value, and transmits the generated power control bit to the base station according to the comparison result. Then, the base station analyzes the power control bit, and then applies it to control the transmission power of the next power control group. The power control method as described above is a method for controlling power when a traffic channel is continuously transmitted through a single transmission antenna. Power control of the traffic channel is performed based on power measurement of the traffic channel signal.

However, discontinuous transmission may occur in a specific channel transmission structure in which a traffic channel is turned on / off. That is, when the base station is equipped with a plurality of antennas and uses the forward transmission diversity scheme, the mobile station performs the handoff function or discontinuous transmission (DTX) depending on whether data is transmitted. As in the case of using a transmission) function, the power control method in a situation in which the traffic channel is turned on / off cannot use the general power control method as described above.

Referring to the case of using the transmit diversity scheme, the transmit diversity scheme is a technique that can be used for the forward link wireless transmission from the base station to the mobile station, and the base station transmits traffic signals through two or more transmit antennas. . Then, the mobile station measures different pilot signal strengths which are always transmitted from the antennas of the base station, and when the mobile station generates and sends a selection signal to the base station, the base station switches to the antenna selected by the selection signal and transmits traffic. In another method, a method of transmitting traffic by changing an antenna every time according to a predetermined conversion pattern may be used.

As described above, when using a transmit diversity scheme of switching on and off traffic through two or more transmit antennas and outputting a traffic signal, a new power control method for controlling power of a signal transmitted from two or more antennas is required. . That is, a method for controlling traffic transmission power for each antenna from a base station of a mobile communication system that transmits traffic signals while switching between two or more antennas using a diversity scheme is required. There is a need for a method for power control of an antenna.

Second, the handoff is when a mobile station communicates with a base station at some point and then with another base station. In the forward link transmission, the mobile station first receives a traffic signal from one base station and at some point a traffic signal from another base station. If you receive. At this time, the power control for the base station transmission is turned on and off to power control the transmission traffic signals of two or more base stations while switching between the base stations.

Third, discontinuous transmission is when there is a period of transmitting a traffic channel signal and a period of no transmission depending on the presence or absence of data. In this case, a method for power control while a traffic channel is not transmitted is needed.

Therefore, when the traffic channel is switched on / off while the base station and the mobile station form a call in the mobile communication system as described above, the traffic channel is turned off during the period in which the traffic channel is not transmitted. After virtually controlling the transmission power, it is necessary to execute power control immediately when communication is resumed.

Accordingly, an object of the present invention is to provide an apparatus and method for controlling the power of a traffic channel switched on / off in a mobile communication system.

Another object of the present invention is to provide an apparatus and method for controlling power of a mobile communication system using a transmit diversity scheme.

It is still another object of the present invention to provide an apparatus and method for controlling power by measuring a power of a signal output from a base station when a mobile station is handed off in a mobile communication system.

It is still another object of the present invention to provide an apparatus and method for measuring and controlling power of a channel in a state in which data is interrupted when using a discontinuous mode according to the presence or absence of data in a mobile communication system.

In order to achieve the above object, a power control apparatus of a mobile communication system according to an embodiment of the present invention has a transmit diversity function and transmits a traffic channel signal through a traffic-on antenna and transmits a traffic channel signal through a traffic offset antenna. And a base station apparatus for outputting a specific common channel signal to transmit a reference value, and receivers according to transmission diversity, wherein the receivers store the traffic power at the time of traffic off and detect a power change of the common channel to detect virtual traffic power. And generate a mobile power control information according to the virtual traffic power, and transmit the mobile station to the base station through the reverse link.

1 is a diagram illustrating a general power control method of a mobile communication system.

2 illustrates a virtual power control method in a mobile communication system according to an embodiment of the present invention.

3 is a diagram illustrating a base station structure of a mobile communication system performing a virtual power control function according to an embodiment of the present invention.

4 is a diagram illustrating a mobile station structure of a mobile communication system performing a virtual power control function according to an embodiment of the present invention.

FIG. 5 is a diagram showing the configuration of a modulator and an interference power meter in a mobile station having the structure as shown in FIG.

FIG. 6 is a diagram showing the configuration of a power control information generator in a mobile station having the structure as shown in FIG.

7 is a diagram illustrating a process of performing a virtual power control function in a mobile station according to the first embodiment of the present invention.

8 is a diagram illustrating a process of performing a virtual power control function at a base station according to the first embodiment of the present invention.

9 is a diagram illustrating a process of performing a power control function of an actual traffic channel in a mobile station according to the first embodiment of the present invention.

10 is a diagram illustrating a process of performing a power control function of an actual traffic channel at a base station according to the first embodiment of the present invention.

FIG. 11 shows transition characteristics of virtual power and pilot power of an antenna with a traffic channel off;

12 is a diagram illustrating a process of performing a virtual power control function in a mobile station according to a second embodiment of the present invention.

13 is a diagram illustrating a process of performing a virtual power control function in a base station according to the second embodiment of the present invention.

14 is a diagram illustrating a process of performing a virtual power control function in a mobile station according to a third embodiment of the present invention.

15 is a diagram illustrating a process of performing a virtual power control function in a base station according to a third embodiment of the present invention.

When controlling the power of a traffic channel in a mobile communication system according to an embodiment of the present invention, a common channel, that is, a perch or a pilot, transmitted at the same fixed power for each antenna in each sector of each base station (Pilot) A channel must always exist to obtain a reference value for transmit power. The transmission powers of the common channels are the same, but are distinguished using different codes in a code division multiple access (CDMA) communication system. That is, different PN sequences (PN sequenc), or orthogonal code (orthogonal code: Walsh code can be used), different, in this case, in order to increase the number of codes may be used Walsh code to extend the length of the Walsh sequence.

An embodiment of the present invention describes a method of controlling the power of a traffic channel that is virtually switched on / off by taking the case of forward transmit diversity as an example. However, the virtual power control method can be easily applied to handoff or discontinuous transmission.

2 is a diagram illustrating a forward power control method of a mobile communication system to which forward transmit diversity is applied. 2 illustrates an example in which a base station uses two transmit antennas. 2 illustrates a case in which power gains of two antennas are individually set to control power of the two antennas separately. In FIG. 2, a portion in bold line indicates a portion in which traffic is transmitted, and a portion in which a line is thin indicates a portion in which only a pilot is transmitted and no traffic is transmitted. Here, it is assumed that the antenna switch time length is relatively longer than the power control group time length.

Referring to FIG. 2, when the base station performs forward transmission to the mobile station, as shown in 212, the base station transmits to one antenna for a time equal to several times the power control group time, and then switches to another antenna. In this case, the switching between the antennas may actually allow the reception of the common pilot signal to be switched to the larger antenna, or may be switched according to a periodic pattern.

Then, the mobile station receives the traffic channel signal from antenna 1 during one power control group as shown in 214 and averages the measured value of the power of the received signal, averages the measured interference power, and calculates the ratio thereof. The power control bit is generated according to the result of comparing the SIR value with the threshold value. The mobile station also receives a common channel signal from antenna 2 during the same power control group and averages the measured power. The virtual power value is calculated from the average value of the received signal power, the amount of change from the previous value of the received value, and the cumulative power control command value, and the average of the measured interference power is used to average the ratio of the virtual power value and the interference power value. The power control bit is generated according to the result of comparing the obtained virtual SIR value with the threshold value. The virtual power value may be obtained by adding a pilot power change amount and a power control command cumulative value to the last measured power value received from the corresponding antenna.

The mobile station then obtains the power of the signals received from the two transmit antennas, and transmits the other two power control bits generated to the base station through the reverse link as shown in 216. Then, when the base station receives the power control bits for antenna 1 and antenna 2 transmitted from the mobile station as shown in step 218, the power gain corresponding to antenna 1 for each transmission of the next power control group according to the power control bits in step 220. Increase or decrease the power gain corresponding to and antenna 2. In this case, the controlled power gain is directly applied to the traffic transmission in the antenna where the traffic channel transmission is performed, and only the power gain value is updated in the antenna where the traffic channel transmission is not performed.

3 shows a structure of a base station transmitter using a transmit diversity scheme according to an embodiment of the present invention. Referring to FIG. 3, a modulator (baseband modulator) 311 receives data to be transmitted, channel codes, spreads, and transmits the received data. The modulator 311 may include a quadrature modulator, a PN diffuser, and the like. The switch controller 313 generates a control signal of the switch 315 for performing the transmit diversity function. The switch 315 switches and outputs the transmission signal output from the modulator 311 to the first antenna ANT1 and the second antenna ANT2 under the control of the switch controller 313. The PCB extractor 317 extracts the PCB from the received data and outputs the PCB.

A gain controller 319 generates the gain control signals G1 and G2 for controlling the channel gain of the transmitted signal by analyzing the power control bits. The multiplier 321 controls the gain of the transmission signal output to the first antenna ANT1 by multiplying the signal output from the switch 315 to the first antenna ANT1 and the gain control signal. The multiplier 323 multiplies the signal output from the switch 315 to the second antenna ANT2 and the gain control signal to control the gain of the transmission signal output to the second antenna ANT2. The adder 315 adds and outputs the first pilot signal and the transmission signal output from the multiplier 321. The adder 317 adds and outputs the transmission signal and the second pilot signal output from the multiplier 323. The RF transmitter 329 up-converts the signal output from the adder 325 into an RF signal and outputs it through the first antenna ANT1. The RF transmitter 331 up-converts the signal output from the adder 327 into an RF signal and outputs the result through the second antenna ANT2. At this time, the signal output through the first antenna ANT1 and the second antenna ANT2 has the form of a signal as shown in 212 of FIG.

Referring to FIG. 3, a transmission operation of a base station performing a transmission diversity function is transmitted to a transmission end of a first antenna ANT1 or a second antenna ANT2 by a switch 315. The transmission signal output to each of the antennas includes a portion that multiplies the gain determined by the gain controller 319. The gain controller 319 determines the gain of the transmission signal output to each antenna by analyzing the power control bit PCB received through the reverse channel.

4 is a diagram illustrating a structure of a mobile station receiver in a mobile communication system performing a transmit diversity function.

Referring to FIG. 4, the RF receiver 412 converts the signal received from the antenna by converting the signal to a baseband signal. The demodulation controller 414 controls the operation of despreading and decoding the received signal. The demodulator 410 despreads and decodes a signal received under the control of the demodulation controller 414. The demodulator may include a PN despreader, an orthogonal demodulator, and the like.

An interference power measurer measures and outputs power of an interference signal included in a received signal output from the RF receiver 412. The traffic signal power measurer 420 measures and outputs the power of the received traffic data signal output from the demodulator 416. The pilot signal power measurer 422 measures the power of the pilot signal output from the demodulator 416. The PCB generator 424 analyzes the power of the signals output from the measuring devices 418, 420, and 422 to generate a power control bit PCB for the forward link according to the received power. The PCB multiplexer 426 multiplexes the power control bits output from the PCB generator 424 to the transmission data of the reverse link.

Referring to the operation of the mobile station receiver having the structure as shown in FIG. 4, the mobile station measures the power of the traffic signal and the pilot signal power of the antenna in which the traffic is off, generates power control bits from them, and reverses the generated power control bits. Send multiplexed to the channel. The demodulator 416 demodulates the traffic signal of the antenna with the traffic channel and the pilot signal of the antenna without the traffic channel according to the command of the demodulation controller 414 to output the traffic data and the pilot signal, respectively. For example, if a traffic signal is transmitted through the first antenna ANT1 and a traffic signal is not transmitted to the second antenna ANT2, the demodulator 416 performs a traffic signal from the first antenna ANT1 and a pilot from the second antenna ANT2. Demodulate the signal. If a traffic signal is transmitted to the second antenna ANT2 and no traffic signal is transmitted to the first antenna ANT1, the traffic signal from the second antenna ANT2 and the pilot signal from the first antenna ANT1 are demodulated.

The demodulated traffic data and the pilot signal are applied to the corresponding traffic signal power measuring instrument 420 and the pilot signal power measuring instrument 422, respectively, and the power measurement values measured and output by the power measuring instruments 420 and 422 are used to generate the power control bits. do. In addition, the interference measurement value output from the interference power meter 418 is also used to generate the power control bit. The mobile station generates a power control bit corresponding to each antenna from the traffic power measurement value and the virtual power measurement value using the pilot signal, and multiplexes it in reverse transmission.

FIG. 5 is a diagram showing the configuration of the demodulator 416 and the respective power meters 418, 420, and 422 in FIG. First, referring to the configuration of the demodulator 416, the multiplier 511 multiplies the PN sequence by the received signal output from the RF receiver 412 to despread the PN. The multiplier 513 multiplies the output of the PN despread multiplier 511 by the orthogonal code of the traffic channel and outputs a signal of the traffic channel from the PN despread signal. The multiplier 515 multiplies the output of the PN despread multiplier 511 by the orthogonal code of the first pilot channel to output the signal of the first pilot channel in the PN despread signal. The multiplier 517 multiplies the output of the PN despread multiplier 511 by the orthogonal code of the second pilot channel to output the signal of the second pilot channel in the PN despread signal. That is, the multipliers 515 and 517 respectively distinguish and output signals of two pilot channels output through different antennas in the base station having the transmit diversity function.

The switch 519 inputs the outputs of the multipliers 515 and 517, and switches and outputs the outputs of the multiplier 515 or the multiplier 517 under the control of the demodulation controller 414. The switch 520 inputs the outputs of the multipliers 515 and 517, and switches the outputs of the multipliers 515 or the multipliers 517 under the control of the demodulation controller 414. The demodulation controller 414 causes the switch 519 to select a pilot channel signal of an antenna with traffic off and the switch 520 to select a pilot channel signal of an antenna with traffic on. That is, the demodulation controller 414 controls the switch 519 and the switch 520 to select pilot channel signals of antennas opposite to each other. At this time, the demodulation controller 414 shares switching information with the switch controller 313 in the base station transmitter through separate signaling or advance appointment.

A channel estimator 521 estimates a channel by inputting the selected pilot channel signal output from the switch 520. A data demodulator 523 demodulates the received data of the traffic channel output from the multiplier 513 using the output of the channel estimator 523 to generate data of the traffic channel. The pilot signal power is measured by inputting another selected pilot signal.

The interference power meter 418 includes an accumulator 531 and a squarer 533, and accumulates and squares a received signal output from the RF receiver 412 to measure interference power included in the signal. The traffic signal power meter 420 includes an accumulator 541 and a squarer 543, and accumulates and squares the signal of the traffic channel output from the demodulator 416 to measure the signal power of the traffic channel. The pilot signal power meter 422 includes an accumulator 551 and a squarer 553, and accumulates and squares a pilot signal output from the demodulator 416 to measure signal power of a pilot channel.

6 is a diagram showing the structure of the PCB generator 424 of FIG.

Referring to FIG. 6, the subtractor 642 subtracts the traffic signal power output from the traffic signal power meter 420 and the interference power output from the interference power meter 418. Comparator 644 generates a power control bit for controlling the power of the channel outputting the traffic signal from the base station by comparing the output of the subtractor 642 and the set threshold value.

The memory 630 includes a power control command value dp1 generated in the previous power control group when the traffic is turned off, a virtual traffic power value updated after being initialized with the last measured actual traffic power, and lpp1 which is a pilot received power measured in the previous power control group. buffers 632, 634 and 636 for storing last pilot power 1 values. The subtractor 612 subtracts the pilot signal power output from the pilot signal power meter 422 and lpp1 of the memory 630 and outputs the subtracted value. The adder 614 adds the output of the subtractor 612 and the virtual traffic power value of the memory 630 to output the sum. The adder 616 adds and outputs the output of the adder 614 and dp1 stored in the memory 630. The subtractor 618 subtracts the output of the subtractor 642 from the output of the adder 616 and outputs the subtractor 642. The comparator 620 generates a power control bit for virtually controlling the traffic power of the channel outputting only the pilot signal without the traffic channel signal by comparing the output of the subtractor 618 with a set threshold value.

When the traffic is off, the buffers 632, 634, and 636 of the memory 630 update and store the changed values. To this end, the delay unit 636 delays the pilot signal power and stores the pilot signal power as lpp1 in the buffer 636 of the memory 630. The delayer 626 delays the output of the adder 624 and stores the virtual traffic power in the buffer 634. Delay 622 delays the output of comparator 620 and stores dp1 in buffer 632.

When the mobile station having the structure as shown in FIGS. 4 to 6 analyzes the signal output from the antenna for transmitting the actual traffic signal and the antenna for outputting only the pilot signal, generates and transmits a power control bit, the base station transmits from the mobile station. The received power control bits are received and analyzed and then applied to gain control for each antenna. In this case, the gain is applied to the actual transmission in the case of the antenna to which the traffic signal is transmitted, but in the case of the antenna in which the traffic transmission is off, the gain is not applied to the actual transmission and is kept updated only until the traffic is turned on. In addition, the base station starts to apply a gain that is not updated until the traffic is turned off the antenna is turned on, but only the update is maintained. At the time when the traffic is off, a gain that is actually applied is not applied, and only the update is maintained.

The base station executes the above power control operation for each antenna and controls switching to the opposite operation when switching between the two antennas occurs. That is, when the base station is in the state of applying the actual power control of the first antenna ANT1, the base station does not perform the actual power control of the second antenna ANT2 and maintains only the power gain and updates the actual power control of the second antenna ANT2. In the state that is applied, only the power gain is maintained without updating the actual power control of the first antenna ANT1.

At this time, in the traffic transmission in the base station, as shown in FIG. 3, the switch 315 is controlled according to the command of the switch controller 313 to switch the traffic data to the two antennas, and the demodulation controller 414 of the mobile station corresponds thereto. Command demodulator 416 to demodulate the traffic and pilot signals from the appropriate antenna. The switching information is shared between the switch controller 313 and the demodulation controller 414 through separate signaling or advance appointment.

7 is a diagram illustrating a virtual power control process in a mobile station according to the first embodiment of the present invention, and FIG. 8 is a process similar to FIG. 7 in which a base station performs a virtual power control process according to a power control command generated by a mobile station. A diagram illustrating an operation for performing the operation.

Referring to FIG. 7, when switching off, the mobile station stores the virtual traffic power of the memory 630 as the last measured actual traffic power in step 711, stores lpp1 as the pilot received power measured in the previous power control group, and stores dp1. Save as the power control command value of the previous power control group. In step 713, it is checked whether a new power control group is applied. In this case, in step 715, the pilot received power of the antenna in which the traffic channel is turned off is measured, and then the first pilot signal power pp1 is used as the pilot received power of the antenna in which the traffic channel is turned off. The virtual traffic power + dp1 + (pp1-lpp1), and the virtual SIR as the virtual traffic power-interference power, and then the previous pilot signal power lpp1 as the current pilot signal power. The structure for measuring the virtual SIR as described above may be configured and implemented as shown in FIG. 6. The power addition and decrease equations shown in this specification represent operations on dB values.

Thereafter, in step 717, the virtual SIR value is compared with the set first threshold value Th1 to determine dp1. If the virtual SIR > Th1, dp1 is determined as -1 in step 719. Otherwise, dp1 is determined as +1 in step 721. do. Thereafter, in step 723, the dp1 value determined as described above is transmitted as the power control bit to the base station. After transmitting the power control bit to the base station as described above, the mobile station checks whether the traffic switch is on in step 725. If the traffic switch remains off, the mobile station returns to step 713 and repeats the above operation. If not, exit the routine.

Referring to FIG. 8, when the traffic switch is turned off, the base station sets the gain control value gain1 of the antenna of which traffic is turned off as the last actual traffic gain in step 812. In step 814, when the power control bit PCB is received from the mobile station, in step 816, the gain gain1 of the transmitter whose traffic is turned off is controlled (gain1 + dp1). If it is detected in step 818 that the new power control group is detected, in step 820, the traffic switch is turned on. If the traffic switch remains off, the process returns to step 814 and repeats the above operation. do.

Therefore, as shown in FIG. 7 and FIG. 8, the virtual power control process in the antenna of the traffic-off transmitter is as follows.

Virtual traffic power = last measured actual traffic power

last pilot power 1 = previously measured pilot received power

dp1 = previous power control command value

From traffic switch off to traffic switch on, repeat the following for each power control group

{

Measuring Pilot Receive Power for Antennas with Traffic Channel Off

pilot power 1 = pilot receive power of the antenna with the traffic channel off

Virtual traffic power = virtual traffic power + dp1

+ (pilot power 1-last pilot power 1)

Virtual SIR = Virtual Traffic Power-Interference Power

last pilot power 1 = pilot power 1

if (virtual SIR> threshold 1)

dp1 = -1

else

dp1 = + 1

PCB (dp1 value) transmission from mobile station to base station

Virtual traffic power (at base station) = virtual traffic power + dp1

}

Therefore, virtual SIR = initial value of virtual traffic power + cumulative power control command value + pilot power change amount-interference power, and the cumulative power control command value is the power control command value (PCB) from the traffic switch off point to the immediately previous power control group. Dp1 values to be sent to the sum.

FIG. 11 is a characteristic diagram illustrating transitions of virtual power and pilot signal power in the antenna in which the traffic channel is turned off as described above. In FIG. 11, a portion indicated by a thin solid line is a diagram showing a transition of pilot signal power, and a portion shown by a thick solid line is a curve showing a transition of virtual power control made according to the transition of the pilot signal power as described above.

FIG. 9 is a diagram illustrating a process of controlling actual traffic power in a mobile station according to an embodiment of the present invention, and FIG. 10 is a process similar to FIG. 9 in which a base station determines an actual traffic channel according to a power control command generated by the mobile station. It is a figure which shows the operation | movement which controls electric power.

Referring to FIG. 9, in operation 911, the mobile station sets the actual traffic power to the last calculated virtual traffic power. Thereafter, in step 913, it is checked whether the new power control group is applied. In step 915, the actual traffic power is measured. In step 915, the actual traffic measurement is performed with actual SIR = actual traffic power-interference power, as shown in FIG.

Thereafter, in step 917, the actual SIR value is compared with the set second threshold value Th2 to determine dp2. If the virtual SIR> Th2, dp2 is determined to be -1 in step 919, otherwise, dp2 is determined to be +1 in step 921. do. Thereafter, in step 923, the dp2 value determined as described above is transmitted as the power control bit to the base station. After transmitting the power control bit to the base station as described above, the mobile station checks whether the traffic switch is off in step 925. If the traffic switch remains on, the mobile station returns to step 913 and repeats the above operation. If not, exit the routine.

Referring to FIG. 10, when the traffic switch is turned on, the base station sets the gain control value gain2 of the antenna of which the traffic is turned on as the last virtual traffic gain in step 1012. If the power control bit PCB (dp2) is received from the mobile station in step 1014, the control gain (gain2 + dp2) of the gain on the transmitter is turned on in step 1016. If it is detected in step 1018 that the new power control group is detected, the traffic switch is checked in step 1020. If the traffic switch remains on, the process returns to step 1014 and repeats the above operation. do.

9 and 10, the actual traffic power control process in the traffic-on antenna is as follows.

Actual traffic power = last calculated virtual traffic power

From traffic switch on to traffic switch off, repeat the following for each power control group

{

Actual traffic power measurement

Real SIR = Real Traffic Power-Interference Power

if (actual SIR> threshold 2)

dp2 = -1

else

dp2 = + 1

PCB (dp2 value) transmission from mobile station to base station

Real traffic power (at base station) = real traffic power + dp2

}

12 and 13 are flowcharts illustrating another embodiment in which the mobile station and the base station control the virtual power when the traffic is turned off. That is, FIG. 12 is a flowchart illustrating a virtual power control process of the mobile station according to the second embodiment of the present invention, and FIG. 13 is a flowchart illustrating a virtual power control process in the base station according to the second embodiment.

Referring to FIG. 12, when switching off, the mobile station stores the virtual traffic power as the last measured actual traffic power in step 1212, and stores the previous pilot power 1 (lpp1) as the measured pilot received power in the previous power control group. , dp1 is stored as the power control command value of the previous power control group, and sum1 is 0. Here, sum1 is a variable that stores the cumulative value of the power control command. In step 1214, it is checked whether a new power control group is applied. In this case, in step 1216, after measuring the reception power of the pilot signal of the antenna in which the traffic channel is off, the first pilot signal power pp1 is the pilot reception power of the antenna in which the traffic channel is off. The power is assumed to be virtual traffic power + dp1 + (pp1-lpp1), and the virtual SIR is set to virtual traffic power-interference power, and then the previous pilot signal power lpp1 is used as the current pilot signal power.

Thereafter, in step 1218, the virtual SIR value is compared with the set first threshold value Th1 to determine dp1. If the virtual SIR> Th1, dp1 is determined to be -1 in step 1220; otherwise, dp1 is determined to be +1 in step 1222. do. Thereafter, in step 1224, the sum1 value is updated by adding the dp1 value determined as described above to the sum1, and in step 1226, the traffic switch on is checked to be ready. If the traffic switch is not in the ready state, the process returns to step 1214 and repeats the above operation to perform the virtual power control operation. However, if the traffic switch is in the ready state, in step 1228 the sum1 value is transmitted to the base station and the routine ends.

Referring to FIG. 13, when the traffic switch is turned off, the base station sets the gain control value gain1 of the antenna whose traffic is turned off as the last actual traffic gain in step 1311. Thereafter, it is checked whether the traffic switch is turned on in step 1313. If the traffic switch remains off, the gain value determined in step 1311 is maintained. However, if the traffic switch is ready to transition to the ON state in step 1313, the sum1 value transmitted from the mobile station is received in step 1315, and in step 1317, the sum1 value is added to the gain1 value determined in step 1311. A new gain control value is set to control the gain on the antenna side to transition to the traffic on state. Thereafter, the apparatus waits until the traffic switch is turned on in step 1319, and outputs a base station transmission signal through the corresponding traffic channel when the traffic switch is turned on.

As described above, the virtual power control method of the second embodiment as shown in FIGS. 12 and 13 does not transmit power control bits for a channel in which traffic is turned off, and has been updated until the traffic is turned on. The power value is sent in the reverse message. In this case, the virtual power control method for the antenna in which the traffic channel is turned off does not send a power control bit (PCB) for each power control group, but instead the virtual traffic power value to be applied to the traffic channel immediately before the traffic channel is switched on. The same is true except that it is sent in a message. Here, the power control bit needs only one bit for the antenna with the traffic channel turned on.

14 and 15 are flowcharts illustrating another embodiment in which the mobile station and the base station control the virtual power when the traffic is turned off. That is, FIG. 14 is a flowchart illustrating a virtual power control process of the mobile station according to the third embodiment of the present invention, and FIG. 15 is a flowchart illustrating a virtual power control process in the base station according to the third embodiment.

Referring to FIG. 14, when switching off, the mobile station stores the virtual traffic power as the last measured actual traffic power in step 1412 and stores the previous pilot power 1 (lpp1) as the measured pilot received power in the previous power control group. . Thereafter, in step 1414, the traffic switch is ready for check. At this time, if the traffic switch is in the off state, the virtual traffic power and the previous pilot signal power determined in step 1412 is maintained while waiting. However, if it detects that the traffic switch on the ready state in step 1414, the interference power is specified in step 1416, after measuring the received power of the pilot signal of the antenna off the traffic channel, the first pilot signal power (pp1) is After the traffic channel is the pilot received power of the off antenna, the virtual SIR is the virtual traffic power + (first pilot signal power-previous pilot signal power)-interference power, and then the previous pilot signal power lpp1 Let pilot signal power.

In step 1418, the first threshold value Th1 is subtracted from the virtual SIR value to determine the step1 value. In step 1420, the step1 value is transmitted to the base station and the routine is terminated.

Referring to FIG. 15, when the traffic switch is turned off, the base station sets the gain control value gain1 of the antenna whose traffic is off in step 1511 as the last actual traffic gain. Thereafter, it is checked whether the traffic switch is turned on in step 1513. If the traffic switch remains off, the gain value determined in step 1311 is maintained. However, if the traffic switch is ready to transition to the ON state in step 1513, in step 1515, a step1 value transmitted from the mobile station is received, and in step 1317, the step1 value is added to the gain1 value determined in step 1511. A new gain control value is set to control the gain on the antenna side to transition to the traffic on state. Thereafter, the apparatus waits until the traffic switch is turned on in step 1519, and outputs a base station transmission signal through the corresponding traffic channel when the traffic switch is turned on.

As described above, the virtual power control method of the third embodiment as shown in FIGS. 14 and 15 does not transmit power control bits for the channel in which traffic is turned off, and measures pilot and interference signals just before the traffic is turned on. It calculates the required power up / down value and sends it in reverse message. That is, the power control value is calculated as follows from the difference between the pilot and interference signal power just before the traffic switch is turned off and the pilot and interference signal power difference just before the switch is turned on.

Power control value = SIR immediately before switch-off + (pilot signal power just before switch-on-pilot signal power just before switch-off)-(interference signal power just before switch-on-interference signal power just before switch-off)-Th1

The mobile station sends the calculated power control value to the base station through a reverse message immediately before the traffic channel is turned on. Here, the power control bit needs only one bit for the channel on which the traffic is turned on. In addition, the mobile station does not have to perform power measurements and virtual power calculations for each power control group.

The virtual power control method performed by the above process works well when there is no transmission error in the channel. However, when many channel errors occur, a random walk problem may occur in which the virtual power value floats away from the actual power value. You can use the following methods to solve this problem. First, if the reverse channel quality is bad (reverse SIR is not good), the received cumulative transmit power control command does not reflect the time command. Secondly, it limits the upper limit of the cumulative command value. Thirdly, the antenna is switched periodically (comparatively large period) to compensate.

In addition, when the virtual power control method according to an embodiment of the present invention is applied at the time of handoff, the antennas belong to different base stations at the time of handoff while the two antennas belong to the same base station in the transmission diversity example. It is assumed that it is located in a base station control station (BSC) that manages two base stations.

When the virtual power control method according to the embodiment of the present invention is applied to a mobile communication system using a discontinuous transmission mode, it is assumed that there is only one antenna and the traffic channel on the antenna is turned on and off.

As described above, the power control method according to the embodiment of the present invention has an effect of efficiently controlling power so that reception performance is improved while minimizing interference to other users when the switch sends out a signal through a transmission antenna on / off. Can be obtained. In particular, there is an advantage in that power control can be performed such that traffic continues to be transmitted while traffic channel transmission is interrupted.

Claims (14)

A power control apparatus of a mobile communication system, comprising: a device for transmitting a traffic channel signal to be switched on and off and having a specific common channel turned on in a switched off state to provide a reference value for transmission power A demodulator for demodulating a received signal to generate a signal of the specific common channel; A common signal power measuring device measuring signal power of the common channel; An interference power measuring device measuring interference power included in the received signal; Inputting the outputs of the power meters, measuring the virtual signal-to-interference ratio by adding or subtracting the change of the pilot signal power and the interference power to the traffic gain when the traffic is off, and comparing the virtual signal-to-interference ratio with a set threshold value With a power control information generator for generating power control information, And transmitting the output of the power control information generator to the transmitting device to control the transmission gain of the traffic channel. The method of claim 1, wherein the power control information generator The virtual traffic power is set to the last traffic power actually measured when the traffic is off, the previous pilot power is set to the pilot power measured from the previous power control group, and the power control command value is set to the power control command value of the previous power control group. After setting, the signal-to-interference ratio measuring unit for calculating the virtual signal-to-interference ratio as shown in <Equation 1> in the power control group unit, And a comparator configured to determine the power control command value by comparing the virtual signal-to-interference ratio with a set threshold value. The power control device of claim 1, wherein the specific common channel is a pilot channel. In the power control device of a mobile communication system, A base station apparatus having a transmit diversity function and outputting a specific common channel signal for transmitting a traffic channel signal through a traffic-on antenna and transmitting a reference value for transmission power through the traffic offset antenna; And receivers according to transmit diversity, wherein the receivers store traffic power at the time of traffic off, detect a power change of the common channel, calculate virtual traffic power, and generate virtual power control information according to the virtual traffic power. And a mobile station transmitting to the base station through a reverse link. 5. The method of claim 4, wherein the mobile station A demodulator for demodulating a received signal to generate a traffic signal and a signal of the specific common channel; A traffic signal power measuring device measuring power of the traffic signal; A common signal power measuring device measuring signal power of the common channel; An interference power measuring device measuring interference power included in the received signal; A second power control information generator for inputting outputs of the power meters and subtracting the traffic power and interference power when the traffic is turned on, and generating power control information of the traffic channel by comparing with a second threshold value; A first power for measuring a virtual signal-to-interference ratio by adding or subtracting a change in the pilot signal power and interference power to the traffic gain when the traffic is off, and comparing the virtual signal-to-interference ratio with a set threshold value to generate power control information; With a control information generator, And controlling the transmission gain by transmitting the outputs of the power control information generators to the transmitter. The method of claim 5, wherein the first power control information generator The virtual traffic power is set to the last traffic power actually measured when the traffic is off, the previous pilot power is set to the pilot power measured from the previous power control group, and the power control command value is set to the power control command value of the previous power control group. A signal-to-interference ratio measurer that calculates a virtual signal-to-interference ratio as shown in Equation 2 below, after setting And a comparator configured to determine the power control command value by comparing the virtual signal-to-interference ratio with a set threshold value. The apparatus of claim 4, wherein the specific common channel is a pilot channel. In the power control method of a mobile communication system having a transmit diversity function, Outputting a specific common channel signal to transmit a traffic channel signal through the traffic-on antenna and to transmit a reference value for transmission power through the traffic offset antenna; After receiving the transmission signal, storing the last actual traffic power at the time of traffic off, detecting power change of the common channel to adjust the traffic power virtually, and generating virtual power control information according to the virtual traffic power. A power control method of a mobile communication system, characterized in that the process consisting of the transmission through the reverse link. The method of claim 8, wherein the receiving the signal to generate virtual power control information comprises: Demodulating a received signal to generate a traffic signal and a signal of the specific common channel; Measuring power of the traffic signal, signal power of the common channel, and interference power included in the received signal; Generating second power control information of a traffic channel by subtracting the traffic power and the interference power when the traffic is turned on and comparing it with a second threshold value; The virtual signal-to-interference ratio is measured by adding or subtracting the change of the pilot signal power and the interference power to the traffic gain when the traffic is off, and generating first power control information by comparing the virtual signal-to-interference ratio with a set threshold value. Consist of, And controlling the transmission gain by transmitting the power control information via a reverse link. The method of claim 9, wherein the generating of the first power control information comprises: The virtual traffic power is set to the last traffic power actually measured when the traffic is off, the previous pilot power is set to the pilot power measured from the previous power control group, and the power control command value is set to the power control command value of the previous power control group. After setting, the process of calculating the virtual signal-to-interference ratio in the power control group unit as shown in Equation 3 below, And determining the power control command value by comparing the virtual signal-to-interference ratio with a set threshold value. The method of claim 8, wherein the specific common channel is a pilot channel. It has a transmit diversity function, and receives a signal output from a base station apparatus that outputs a specific channel channel signal for transmitting a traffic channel signal through a traffic-on antenna and a reference value for transmission power through a traffic offset antenna. In the power control method of a mobile communication system for controlling the power of the forward link, When the traffic is off, the virtual traffic power is set to the final actual traffic power, the previous pilot power is set to the pilot power measured in the previous power control group, and the power control command value is set to the power control command value of the previous power control group. Process, Measuring pilot power of the traffic-off antenna in the power control group period; Measuring a virtual signal-to-interference ratio of the traffic-off channel by Equation 4 below; Determining a power control command value for controlling a transmission power of a base station by comparing the signal-to-interference ratio with a set threshold value; And transmitting the power control command value to the base station. It has a transmit diversity function, and receives a signal output from a base station apparatus that outputs a specific channel channel signal for transmitting a traffic channel signal through a traffic-on antenna and a reference value for transmission power through a traffic offset antenna. In the power control method of a mobile communication system for controlling the power of the forward link, When the traffic is off, the virtual traffic power is set to the final actual traffic power, the previous pilot power is set to the pilot power measured in the previous power control group, and the power control command value is set to the power control command value of the previous power control group. , Initializing the cumulative variable, Measuring pilot power of the traffic-off antenna in the power control group period; Measuring the virtual signal-to-interference ratio of the traffic-off channel by Equation 5 below; Determining a power control command value for controlling a transmission power of a base station by comparing the signal-to-interference ratio with a set threshold value; Adding the power control command value to the cumulative variable to update the cumulative variable and transitioning to a traffic-on state; if not, repeating the process; And transmitting the cumulative variable to the base station when the traffic is switched on in the process. It has a transmit diversity function, and receives a signal output from a base station apparatus that outputs a specific channel channel signal for transmitting a traffic channel signal through a traffic-on antenna and a reference value for transmission power through a traffic offset antenna. In the power control method of a mobile communication system for controlling the power of the forward link, Setting the virtual traffic power to the final actual traffic power at the time of traffic off, and setting the previous pilot power to the pilot power measured in the previous power control group; Checking whether the traffic on switching state is performed after performing the process, and if not, maintaining the state; Measuring the interference power and the pilot power at the time of the traffic on state transition; Measuring a virtual signal-to-interference ratio of the traffic-off channel by Equation 6 below; And subtracting a predetermined threshold value from the signal-to-interference ratio, and transmitting the subtraction result as power control information to the base station.