KR100274087B1 - Reverse power control apparatus and method for reducing interference - Google Patents

Abstract

PURPOSE: A reverse power control apparatus and method for reducing interference is provided to gain a similar effect with an order of increasing of power and reduce an interference about a neighboring cell and lengthen a time using a battery of terminal by reducing a transmitting power of the terminal. CONSTITUTION: A power control order generating unit generates a power control order by receiving and analyzing the transmitting signals of terminals. A power control unit examines the power control bits, and when a power increasing order exceeds a set point, generates a power decreasing order. A multiplexing unit generates the transmitting signal by multiplexing an output the power control unit to the transmitting signal of a base station.

Description

Reverse power control device and method for reducing interference

The present invention relates to an apparatus and method for controlling power of a spread spectrum communication system, and more particularly, to an apparatus and method for controlling power of a terminal in a base station.

In general, in a spread spectrum communication system, in order to obtain a reception signal having a desired strength, a base station compares a transmission power of a terminal with a threshold value, and instructs the transmission power of the terminal to decrease in large cases and an increase in small cases. In a communication system using a spread spectrum communication method, it is preferable to reduce the transmission power of a terminal because it reduces the amount of interference from another terminal's point of view.

The operation of controlling the power of a terminal in a conventional code division multiple access communication system will be described. First, the reception operation of the base station, the demodulator receives and demodulates the signal transmitted from the terminal and outputs. In this case, the demodulator may include an RF demodulator for frequency converting a received RF signal into a baseband, and a baseband demodulator for despreading the baseband converted signal and demodulating the original signal. . A signal power measurement part receives the output of the demodulator and measures the signal power to receive a received signal strength indicator (RSSI), a signal-to-interference ratio (SIR) or Measures the quality of a signal such as a bit error rate (BER). The power generator generates a power control bit (PCB) by receiving the power measurement result.

Second, referring to a reception operation of a base station, a PCB multiplexer multiplexes the power control bits to a transmission signal output from the baseband signal processor. The modulator modulates the transmission signal including the power control bit output from the multiplexer 33 at high frequency and outputs the modulated signal. The adder adds and outputs the transmission signals output from the modulator 35, and the RF signal processor converts the transmission signal output from the adder into an RF signal and outputs the RF signal.

However, as the base station increases the transmission power of the terminal as described above, since interference increases from the standpoint of the terminal, this causes a deterioration of the quality of the magnetic signal, and to compensate for this, an increase in the transmission power of the magnetic signal is required. This resulted in a problem that caused a vicious cycle of quality deterioration to be repeated.

Accordingly, an object of the present invention is to provide an apparatus and method for controlling a transmission power of a terminal by a base station in a mobile communication system.

Another object of the present invention is to reduce the transmission power of all the terminals that need to be increased if the number of terminals that need to be increased when the base station controls the transmission power of the terminal in the mobile communication system is larger than the set threshold value. The present invention provides an apparatus and method for reducing power interference by other terminals by controlling power in a reverse direction.

The terminal power control method of the mobile communication system according to an embodiment of the present invention for achieving the above object, the process of setting the channel number threshold for executing the reverse power control, the effective number of channels currently being serviced for a certain period of time and Comparing the threshold value, and performing a reverse power control process of transmitting a power reduction command to the corresponding terminals when the effective number of channels currently being serviced is greater than the threshold value in the comparison process; A normal power control process for transmitting a power control command to the corresponding terminals may be performed.

1 is a diagram showing the configuration of an apparatus for controlling a transmission power of a terminal by a base station in a code division multiple access communication system;

2 is a flowchart illustrating a process of controlling a transmission power of a terminal in a base station according to an embodiment of the present invention.

3 is a flowchart illustrating a process of controlling a transmission power of a terminal in a base station according to another embodiment of the present invention.

4 is a flowchart illustrating a process of controlling a transmission power of a terminal in a base station according to another embodiment of the present invention.

In the mobile communication system, if the base station measures the signal quality such as signal strength, signal-to-interference ratio, or bit error rate from the terminal, and does not reach the desired level, it is necessary to increase the transmission power of the terminal to improve the quality. . In this case, the base station instructs the mobile station to increase the transmit power by using a power control bit such as a power control bit. For example, it would be a way to send a value of "0" when requesting an increase in transmit power and a value of "1" when requesting a decrease. In an embodiment of the present invention, the number of effective numbers of terminals or channels requiring an increase in transmission power is determined and compared with a threshold set in the base station. At this time, if the threshold value is smaller than the threshold value, the power control of all terminals is performed in the same manner as the conventional method. Perform a reverse power control command.

1 is a diagram illustrating a configuration of a base station for controlling power of a terminal in a base station in a code division multiple access communication system according to an embodiment of the present invention.

Referring to FIG. 1, the demodulator 13 receives, demodulates, and outputs a signal transmitted from the terminal. The demodulator 13 may include an RF demodulator for frequency converting a received RF signal into a baseband, and a baseband demodulator for despreading the baseband converted signal and demodulating the original signal. . A signal power measurement part 15 receives the output of the demodulator 13 and measures signal power to receive a received signal strength indicator (RSSI) and a signal-to-interference ratio (SIR). Or measure the quality of the signal, such as the bit error rate (BER). The power generator bit generator 17 receives the power measurement result and generates a power control bit (PCB). The baseband signal processor 19 configures a function of processing channel signals output from the baseband demodulator of the demodulator 13.

The reverse power controller 100 analyzes the power control bits output from the PCB generators 17 and generates power control signals for controlling transmission power of the terminals. At this time, the reverse power controller 100 analyzes the power control bits and generates a power control signal for reducing the power of all terminals when a power control increase command is generated. That is, the reverse power controller 100 analyzes the values of the power control bits of the PCB generators 17 and determines that inversely, commanding the output power reduction rather than the base station commanding the output power increase of the terminal improves the situation of the system. In the following case, the base station instructs the terminals in the cell to control the transmission power. An exclusive OR gate 31 performs an exclusive OR on the outputs of the PCB generator 17 and the outputs of the reverse power controller 100 and outputs the power control command.

The baseband signal processor 41 processes transmission data for transmission from the base station to each terminal. A PCB multiplexer 33 multiplexes the power control bits to a transmission signal output from the baseband signal processor 41 and outputs the multiplexed power control bits. The modulator 35 modulates and transmits the transmission signal including the power control bit output from the multiplexer 33 at a high frequency. The adder 35 adds and outputs the transmission signals output from the modulator 35. The RF signal processor 39 converts the transmission signal output from the adder 37 into an RF signal and outputs the RF signal.

In FIG. 1, the reverse power controller 100 includes a controller for processing a program as illustrated in FIG. 2, a memory for storing a program for executing the program as illustrated in FIG. 2 and data generated during program execution. And the like.

2 is a flowchart illustrating a process of controlling power of a terminal in the reverse power controller 100 of the base station as described above. In Figures 2, 3 and 4, m means the number of the terminal in service. T _P means a threshold of the effective number of channels for reverse power control. N means the effective number of channels that should command power increase. Q is a variable for storing the number of terminals to command power increase. M means the number of terminals currently in service. H means the effective number of currently serving channels calculated based on the most basic channel. C [m] is a power control command for the terminal, where “0” is a command for increasing the output power of the terminal m and “1” is a command for reducing the output power of the terminal m. DR [m] means an increase function according to the transmission data rate or the transmission data rate of the terminal m. (m = 1,2, ..., M) When all terminals perform the same service with the same data rate in a single code method, the number of channels and the number of terminals are the same. However, the effective number of channels depends on the data rate and the quality of service required. For example, if the same bit energy-to-interference ratio is required, serving 64 kbps with a single code is considered to use approximately twice as many channels as serving 32 kbps with a single code. Are the same, but the effective number of channels may be different. When the same data rate is transmitted but the required bit energy-to-interference ratio is 2 times (3 dB), it requires relatively twice the output power. Therefore, the effective number of channels is smaller than the case where the required bit energy-to-interference ratio is small as in the above case. Can be seen as twice.

A case where the effective number H of the channels being served and the number M of terminals are the same when all terminals perform the same service having the same data rate in a single code manner without departing from the gist of the present invention will be described.

Referring to FIG. 2, the reverse power controller 100 of the base station sets a threshold value T _P for reverse power control in step 111, checks the number M of terminals currently in service in step 113, and then, in step 115, the current service. The number M of active terminals and the threshold value T _P are compared.

The number M of terminals includes all currently serving channels to command power increase and decrease. If the number M of terminals is less than the threshold value T _P , the process waits for a predetermined time in step 117 and returns to step 113 to repeat the above process.

If the number M of terminals currently being serviced is greater than the channel threshold value T _{P in} step 115, the initialization operation is performed for power control in step 119. In the initialization process, the number Q of the terminal to command the power increase is set to 0, and the terminal number m is set to 1.

Thereafter, steps 121 to 129 are performed to sequentially check all channels currently being serviced, and to check power control values required for the corresponding channels. For this purpose, it is checked in step 121 whether the terminal number m currently being checked is the final terminal number. That is, in step 121, it is checked whether the current terminal number m is larger than the number M of terminals currently being serviced. If m is smaller than M, in step 123, the power control value required for the terminal is C [m] = 0. Check it. Here, if C [m] = 0, the command indicates an increase in transmission power of the corresponding terminal. If C [m] = 1, it indicates a decrease in transmission power of the corresponding terminal. In step 123, if C [m] = 0, in step 125, the number of terminals to command power increase is increased by 1 (N = N + 1), and in step 127, P [Q is the Qth storage location of the corresponding terminal number. ]. If C [m] = 1 in step 123, the flow proceeds directly to step 129. After completing the current test, the terminal number m is increased (m = m + 1) in step 129 and the process returns to step 121 above.

While repeating the above process, it checks the power request of the terminals currently in service, and stores the terminal number that needs to be increased. In addition, the number Q of terminals requesting power increase is accumulated and stored.

In this case, if the current terminal number is the last terminal number (m = M) currently being serviced in step 121, the number of terminals Q to which the power increase command should be sent in step 131 is compared with the threshold channel number T _P for reverse power control. . In this case, if Q is less than T _P , there is no need to perform reverse power control. Therefore, the process proceeds to step 141 and waits for a predetermined time before returning to step 113.

However, if Q is greater than T _P in step 131, the reverse power control process is performed. Then, the base station initializes the terminal number n to perform reverse power control to 1 in step 133, and checks whether the current terminal number n which has performed the reverse power control process in step 135 is less than the total number Q of terminals to be reverse power controlled. (N ≦ Q). Here, the variable n is an address of a table that stores the number of channels that have undergone the reverse power control process. In step 135, the reverse power control of all channels requiring the reverse power control process is examined.

In this case, if the condition of n≤Q is satisfied in step 135, a reverse power control process should be performed. In step 137, reverse power control is commanded to reduce transmission power to the channel number corresponding to n (C [P [n]). ] = 1), in step 139, after increasing the address of the table in which the channel number requiring the next reverse power control is stored (n = n + 1), the process returns to step 135 above. The reverse power control operation as described above is repeatedly performed until n> Q.

Referring to FIG. 3, the reverse power controller 100 of the base station sets a threshold value T _P for reverse power control in step 111, checks the number M of terminals currently in service in step 113, and then, in step 115, the current service. The number M of active terminals and the threshold value T _P are compared.

The number M of terminals includes all currently serving channels to command power increase and decrease. If the number M of terminals is less than the threshold value T _P , the process waits for a predetermined time in step 117 and returns to step 113 to repeat the above process.

If the number M of terminals currently being serviced is greater than the threshold value T _{P in} step 115, the initialization operation is performed for power control in step 319. In the initialization process, the effective number N of channels to command power increase is set to 0, the number Q of terminals to command power increase is set to 0, and the channel number m is set to 1.

Thereafter, steps 121, 123, 325, 326, 127, and 129 are sequentially performed to sequentially check all channels currently being serviced, and to check power control values required for the corresponding channels. For this purpose, it is checked in step 121 whether the terminal number m currently being checked is the final terminal number. That is, in step 121, it is checked whether the current terminal number m is larger than the number M of terminals currently being serviced. If m is smaller than M, in step 123, the power control value required for the terminal is C [m] = 0. Check it. Here, if C [m] = 0, the command indicates an increase in transmission power of the corresponding terminal. If C [m] = 1, it indicates a decrease in transmission power of the corresponding terminal. If C [m] = 0 in step 123, the effective number of channels to command power increase is increased by one (N = N + 1) and the number Q of terminals requiring power increase is increased by one. In step 127, the terminal number m is stored in P [Q], which is the Qth storage location. If C [m] = 1 in step 123, the effective number of channels to command power increase is decreased by 1 in step 326. (N = N-1) In step 129, the terminal number m is increased in step 129 after the completion of the current inspection (m = m + 1), and the process returns to step 121 above.

By repeating the above process, the power increase / decrease request of the terminals currently in service is examined. The effective number N of the channels requiring the power increase is accumulated and stored.

In this case, if the current terminal number is the last terminal number (m = M) currently being serviced in step 121, the number of channels to be increased in power N and the threshold number of channels T _P for reverse power control are compared in step 331. In this case, if the number N of the channels requiring the power increase is less than the threshold number of channels T _P , there is no need to perform reverse power control. Therefore, the process proceeds to step 141 and waits for a predetermined time before returning to step 113.

However, if the effective number N of the channels requiring the power increase in step 331 is greater than the threshold number of channels T _P , a reverse power control process is performed. Then, the base station initializes the channel number n to perform reverse power control to 1 in step 133, and checks whether the current channel number n, which has performed the reverse power control process in step 335, is less than the number Q of terminals to be controlled in reverse power. (N ≦ Q). Here, the variable n is an address of a table that stores the number of channels that have undergone the reverse power control process. In step 135, the reverse power control of all channels requiring the reverse power control process is examined.

In this case, if the condition of n≤Q is satisfied in step 335, a reverse power control process should be performed, so in step 137, reverse power control is commanded to reduce transmission power to the channel number corresponding to n (C [P [n]). ] = 1), in step 139, after increasing the address of the table in which the channel number requiring the next reverse power control is stored (n = n + 1), the process returns to step 335. The reverse power control operation is repeatedly performed until n> Q.

Referring to FIG. 4, the reverse power controller 100 of the base station sets a threshold value T _P for reverse power control in step 111. In step 413, the number M of terminals currently in service and the transmission data rate DR of each terminal [ m]. (m = 1,2,3, ..., M). In operation 414, the effective number H of the terminal currently being serviced is calculated based on the value and the required quality of service. In operation 415, the effective number H of the currently serving terminal is compared with the threshold value T _P.

The number M of terminals includes all currently serving channels to command power increase and decrease. If the number M of terminals is less than the threshold value T _P , the process waits for a predetermined time in step 117 and returns to step 113 to repeat the above process.

In this case, if the effective number H of the currently serving terminal is greater than the channel threshold value T _{P in} step 115, the initialization operation is performed for power control in step 419. In the initialization process, the number N of channels to command power increase is set to 0, the number Q of terminals to command power increase is set to 0, and the channel number m is set to 1.

Subsequently, steps 121, 123, 425, 426, 127, and 129 are sequentially performed to sequentially check all channels currently being serviced to check power control values required for the corresponding channels. For this purpose, it is checked in step 121 whether the terminal number m currently being checked is the final terminal number. That is, in step 121, it is checked whether the current terminal number m is larger than the number M of terminals currently being serviced. If m is smaller than M, in step 123, the power control value required for the terminal is C [m] = 0. Check it. Here, if C [m] = 0, the command indicates an increase in transmission power of the corresponding terminal. If C [m] = 1, it indicates a decrease in transmission power of the corresponding terminal. If C [m] = 0 in step 123, the effective number of channels to command power increase in step 425 is increased by an amount DR [m] proportional to the transmission data rate of the corresponding terminal (N = N + DR [m]). Increase the number Q of terminals that need to increase power by one. In step 127, the terminal number m is stored in P [Q], which is the Qth storage location. If C [m] = 1 in step 123, the effective number of channels to command power increase is reduced by an amount DR [m] proportional to the transmission data rate of the corresponding UE in step 426. (N = N-DR [m ]) DR [m] is an increase function according to the transmission data rate or the transmission data rate of the terminal m. After completing the current test, the terminal number m is increased (m = m + 1) in step 129 and the process returns to step 121 above.

While repeating the above process, it checks the power request of the terminals currently in service, and stores the terminal number that needs to be increased. The effective number N of the channels requiring the power increase is accumulated and stored.

In this case, if the current terminal number is the last terminal number (m = M) currently being serviced in step 121, the effective number N of channels to increase power is compared with the critical channel number T _P for reverse power control in step 431. In this case, if the effective number N of the channels requiring the power increase is less than the threshold number of channels T _P , there is no need to perform reverse power control. Therefore, the process proceeds to step 141 and waits for a predetermined time before returning to step 413.

However, if the effective number N of channels for which the power increase is requested in step 431 is greater than the threshold number of channels T _P , a reverse power control process is performed. Then, the base station initializes the terminal number n to perform reverse power control to 1 in step 133 and checks whether the current terminal number n, which has performed the reverse power control process in step 435, is smaller than the number Q of terminals to be controlled in reverse power. (N ≦ Q). Here, the variable n is an address of a table that stores the number of terminals that have undergone the reverse power control process. In step 435, it is checked whether reverse power control of all terminals that require reverse power control process is finished.

In this case, if the condition of n≤Q is satisfied in step 435, a reverse power control process should be performed, so in step 137, reverse power control is commanded to reduce the transmission power to the terminal corresponding to n (C [P [n]]). = 1), after increasing the address of the table in which the terminal number requiring the next reverse power control is stored (n = n + 1) in step 139, the process returns to step 435. The reverse power control operation as described above is repeatedly performed until n> Q.

As described above, when the base station measures the signal quality such as the received signal strength, signal-to-interference ratio, bit energy-to-interference ratio, or bit error rate from the terminal, and does not reach the desired level, the conventional method uses the power of the corresponding terminal. To increase the quality. At this time, when the command to reduce the transmission power outputs a command to reduce the transmission power as it is. However, in the present invention, when commanding the transmission power increase, after confirming how many terminals need to increase the transmission power, if the base station has less than the threshold value T _P which the base station has, the same process as the conventional power control method is performed. However, if the base station has more than the threshold value T _P , the reverse power control process is performed to instruct a decrease in transmit power to all terminals attempting to increase the transmit power. If the signal from the same terminals that received the command and lowered the transmission power even after performing the above process by the threshold value T _P does not have the desired quality, the existing power control method within the allowed range until the transmission power increase is not necessary. Alternating with reverse power control.

As described above, in a mobile communication system, a base station has a threshold value for the number of terminals, effective number of channels, or power level for reverse power control, and channels currently being serviced when the base station controls transmission power of terminals. If the sum of the effective number or the total power level of the channel that requires an increase in the power exceeds the channel threshold, a command is outputted to reduce the transmission power. By reducing the transmission power of the terminal as described above, interference by signals of other terminals is reduced, so that an effect similar to when power is commanded can be obtained, and interference to adjacent cells can be reduced, and due to the reduction of terminal transmission power. There is an advantage in that the battery life of the terminal can be extended.

Claims (7)

An apparatus for controlling power of a terminal in a base station of a mobile communication system, Power control command generators for receiving and analyzing transmission signals of terminals to generate a power control command; A power controller for inspecting the power control bits and generating power reduction commands when a power increase command exceeds a set value; And a multiplexing unit configured to generate a transmission signal by multiplexing an output of the power control unit to a transmission signal of the base station. The method of claim 1, wherein the power control unit, The power control commands are inputted and compared with a threshold value of the number of channels for reverse power control, and the number of power increase request channels is compared to the corresponding terminals when the effective number of channels that require the power increase is compared with the threshold value. A reverse power controller for generating a power reduction command in reverse; And a comparator configured to compare outputs of the reverse power controller and outputs of the power control command generators to generate a power control command of the terminal. 3. The terminal power control apparatus of a mobile communication system according to claim 2, wherein said comparator is an exclusive logical summator. An apparatus for controlling power of a terminal in a base station of a mobile communication system, Generating a power control command of the terminal by analyzing signals transmitted from the terminals; Analyzing the power control command and commanding the output power reduction of the terminal rather than the command to increase the output power of the terminal, when it is determined that the situation of the system improves the command to the terminal in the cell managed by the base station to reduce the transmission power Terminal power control method of a mobile communication system, characterized in that consisting of a process. The method of claim 4, wherein generating the power control command comprises: And if the number of channels of the power increase command is greater than the number of effective channels for increasing power, the terminal reverse power control method of the mobile communication system. In the terminal power control method of a mobile communication system, Setting a channel number threshold for executing reverse power control; Calculating the effective number of channels currently in service; Comparing the threshold with an effective number of channels currently in service at a predetermined time period; In the comparison process, if the effective number of channels currently being serviced is greater than the threshold value, the process of checking whether the power increase or decrease is requested in order of the number of channels being serviced is stored together with the channel number which is the power increase, and checking the number of power increase channels. and, And transmitting a power reduction command to the corresponding terminals only when the number of channels requiring the power increase is greater than a threshold value. 7. The method of claim 6, wherein the threshold comprises a power level.