KR100223365B1 - Apparatas and method for tracking transmission power in cdma communication system - Google Patents

Abstract

In the implementation of the transmitter of the mobile communication system, a power detector is provided in each transceiver, and the transmission / reception controller compares the actually detected transmission power with the reference transmission power and variably controls the gain of the transmission signal to be a constant output.

A transmitting apparatus of a mobile communication system according to an embodiment of the present invention includes a detecting unit connected to each transmitting and receiving unit to detect transmission power, receives channel gain values output from a channel element, calculates a reference transmission power value, The actual transmission power value output from the detection unit is compared with the calculated transmission power value, and the gain of the transmitter is variably adjusted by obtaining an error value when the two transmission power values are different from each other.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and method for tracking transmission power of a mobile communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a transmitter and a transmitter control method for a mobile communication system, and more particularly, to an apparatus and a method for controlling transmission power in a transmitter.

Generally, a mobile communication system measures transmission power of a base station and then controls transmission power according to a measurement result. For this purpose, a directional coupler of a base station transmission RF stage is connected and the power of a transmission signal output from the directional coupler is measured using a power measuring device.

FIG. 1 is a diagram illustrating a structure for tracking transmission power in a mobile communication system. FIG. 2 is a diagram illustrating a structure of a transmission power tracking loop (hereinafter referred to as TPTL) . 1 and 2, the transmission / reception unit includes a transceiver main controller 24, a transceiver 23, an amplifier (Liner Power Amplifier) 22, and a coupler directional coupler 21, and is configured for each sector. FIG. 1 shows an example of three sectors of?,?, And?. The channel element 11 outputs sector-specific traffic data to the transmission / reception main part 24 of the corresponding sector, and the transmission / reception main part 24 outputs traffic data for each frequency to the corresponding transmission / reception part 23. The transceiver 23 includes a transmitter, a receiver, and transmission / reception controllers, and the transmitter includes an upconverter and a variable attenuator for up-converting a transmission signal to an RF signal. The power detector 14 detects and outputs the transmission power for each sector output from the directional couplers 21a-21c connected to the final output terminal of each sector transceiver unit. The power detection control unit 15 outputs the transmission power for each sector output from the power detector 14 through the system communication line 16. [ The TPTL control unit 13 receives the transmission power of each sector received through the system communication line 16, calculates an error, and compensates.

The conventional technique as described above includes a power detector 14 for detecting transmission power of each sector, a TPTL controller 13 for collectively processing the transmission power, and a path switching unit for selecting each transmission sector, As shown in FIG.

Particularly, when the mobile communication system is a CDMA (Code Division Multiplexing Access) system, power control always occurs due to system characteristics. Therefore, in the CDMA system, in order to compensate the difference between the actually measured power and the transmission power difference required in the system, information on the system traffic at the time of measurement is required. That is, the TPTL controller 13 collects all the synthesized information such as the number of traffic at the time of measurement, the activity of the traffic, the digital gain of the traffic, the gain of the transmission RF stage, And determines whether there is an error in the transmission power. If an error occurs in the transmission power, the TPTL controller 13 controls the variable attenuator located in the transmitter of the corresponding base station transmitter 23 to adjust the transmission gain. Also, in this case, it is necessary to transmit information between the traffic control units responsible for the traffic, the base station transmission RF control unit, the control unit of the power detector 14, and the TPTL control unit 13, which is a main process for tracking the transmission power.

As described above, in the conventional transmission power tracking algorithm, since a lot of information is transmitted between many processors and these information must be processed, the overall configuration becomes very complicated, causing a large load on the communication line between the system building blocks, A high performance system is required to track power control.

As a method for solving the problems occurring in the conventional transmission tracking loop structure, the transmission power generated in the various sectors is collectively determined, and the transmission power is independently controlled in each sector. That is, a single power detector 15 measures the transmission power generated by each sector and frequency, processes all the data in the controller, and transmits the data to the corresponding RF controller. In each RF controller, It is preferable to use a method of directly measuring and correcting errors.

It is therefore an object of the present invention to provide a transmission apparatus and method in which a transmitter unit of each sector in a mobile communication system independently detects a transmission power and calculates an error of transmission power and directly compensates.

It is another object of the present invention to provide an apparatus and method for correcting an error transmission power of a transmitter by calculating an error value after a transmitter has a power detector and detecting a transmission power output from a corresponding transmitter in a CDMA system .

According to another aspect of the present invention, there is provided a transmission apparatus for a mobile communication system, including a detection unit connected to each transmission / reception unit and detecting transmission power, The transmission power value is calculated, the actual transmission power value output from the detection section is compared with the calculated transmission power value, and the gain value of the transmitter is variably adjusted by obtaining an error value when the two transmission power values are different .

1 is a diagram showing a configuration of a conventional mobile communication system

FIG. 2 is a diagram showing in a simplified manner a configuration for tracking the transmission power of a transmitter and a transmitter in FIG.

3 is a diagram showing a configuration for tracking transmission power of a transmitter according to an embodiment of the present invention;

4 is a diagram showing the configuration of the transmitter in Fig. 3

5 is a flowchart illustrating a process of tracking the transmission power of a transmitter according to an embodiment of the present invention.

3 is a diagram illustrating a structure of a transmission power tracking loop for measuring and correcting transmission power in a transmitter of a mobile communication system according to an embodiment of the present invention. Referring to FIG. 3, a channel element 11 outputs transmission / reception data to the corresponding transmission / reception unit 35 under the control of the channel element and the system interface control unit 31. The channel element and system interface control unit 31 outputs traffic information through a system communication line. The transmission / reception unit 15 modulates the frequency of the transmission data modulated by the corresponding channel element 32 and outputs the frequency of the transmission data output from the system interface unit 33 under the control of the transmission / reception main control unit 34, and converts it into an RF signal. The transmission / reception unit 35 detects the power of the RF signal transmitted at the current channel frequency, detects the transmission power of the currently output RF signal by performing a transmission power tracking loop, and detects the transmission power between the detected value and the calculated power value Obtain an error and compensate for it. An amplifier (LPA) 36 amplifies the transmission RF signal output from the transmission / reception unit 35 and outputs the amplified transmission RF signal through an antenna 37. A directional coupler 37 is connected to an output terminal of the amplifier 36, separates the RF signal output from the amplifier 36, and outputs the RF signal to the transceiver 35. The transmission / reception main control unit 34 is connected to the system communication line and controls the operation of the plurality of transmission / reception units 35 under the control of the upper control unit.

The transmission / reception unit 35 includes a transmitter, a receiver, and transmission / reception control units. In the embodiment of the present invention, since the transmission power is tracked and the error is corrected, the description of the configuration and operation of the receiver will be omitted. The transmitter-receiver unit 35 according to an embodiment of the present invention includes a transmitter 41, a power detector 42, and a transmitter-receiver controller 43. The transmitter 41 up-converts the frequency of the channel data output from the corresponding channel element 32 and input through the system interface 41 to generate a transmission RF signal. The transmitter 41 includes a variable attenuator to adjust the gain of the RF signal transmitted by the received attenuation control signal. The power detector 42 is connected to the directional coupler 37 and detects a transmission power of an RF signal transmitted through a corresponding channel. The transmission / reception control unit 43 controls the operation of the transmitter 41. Also, the base station receives the transmission power output from the power detector 42, calculates a reference transmission power value according to the current number of traffic, compares the received transmission power with the received transmission power to obtain an error, generates an attenuation control signal corresponding to the error, And controls the variable attenuator of the transmitter 41.

3 shows a detailed configuration of the transceiver 35. The transmitter 41 includes a primary up-conversion unit including amplifiers 51 and 54, a mixer 52, and an IF filter (intermediate filter) 53, a mixer 55, 56, and an amplifier 57, and a variable attenuator 58. In the present embodiment, The first up-conversion unit mixes the IF signal (4.95 MHz) of the channel output from the system interface unit 33 with the local frequency LO1 (110 MHz) generated by the first local oscillator 67 of the frequency synthesizer, And generates a rising frequency IF1. At this time, the IF filter 53 filters the IF + LO1 frequency and outputs the IF1 raised. The second up-conversion unit mixes the IF1 signal (IF + LO1) output from the first up-conversion unit and the local frequency LO2 (frequency in the UHF band) generated by the second local oscillator 66 of the frequency synthesizer 44, And generates a rising frequency IF2. Here, since the second local frequency LO2 is a frequency for determining a channel, the second rising frequency IF2 is channel-determined and up-converted by the second local frequency IF2. At this time, the IF filter 56 filters the frequency of IF1 + LO2 and outputs the IF2 raised. Here, the IF2 signal is an up-converted RF signal. The variable attenuator 58 is a voltage-controlled attenuator that is located in the transmitter 41 and adjusts the gain of the up-converted RF signal. The variable attenuator 58 adjusts the output gain of the RF signal up-converted by the attenuation control signal output from the transmission /

The power detector 42 detects the power of the RF signal output from the directional coupler 37. Referring to the configuration of the power combiner 42, the mixer 61 mixes a second local frequency LO2 output from the second local oscillator 66 of the frequency synthesizer 44 with an RF signal coupled by the directional coupler 37. A filter (SAW filter) 62 down-converts the mixed signal output from the mixer 61 to filter the IF signal of the corresponding channel band. The detection unit 63 converts the IF signal of the channel output from the filter 62 into a voltage value, and detects and outputs the transmission power of the transmission RF signal. The detection unit 63 may include an envelope detector and an operational amplifier. Therefore, the power detector 42 down-converts and filters the signal coupled to the directional coupler 37 at the front end of the transmitting antenna 37 using the same local frequency of the transmitted RF signal, thereby converting the RF signal It is possible to accurately detect the transmission power of the mobile station.

The frequency synthesizer 44 generates the first local frequency LO1 and the second local frequency LO2 of the transmitter 41 under the control of the transmission / Referring to the configuration of the frequency synthesizer 44, the first local oscillator 67 generates a first local frequency LO1 of 110 MHz under the control of the transmission / reception controller 43, and outputs the first local frequency LO1 to the mixer 52. The second local oscillator 66 generates a second local frequency LO2 in the UHF band under the control of the transmission / reception controller 43, and outputs the second local frequency LO2 to the mixer 55 and the mixer 61.

The transmission / reception control unit 43 controls the function and state of each module in the corresponding transceiver 35 under the control of the transmission / reception main control unit 34, and controls and processes communication and alarm with the transmission / reception main control unit 34. The transmission / reception control unit 43 performs a function of tracking the transmission power of the corresponding transceiver 35 to obtain an error, and compensating transmission power according to the error. An analog-to-digital converter (ADC) 64 is connected to the detector 63 of the power detector 42 and converts the transmission power output from the detector 63 into digital data. The D / A converter 65 converts the attenuation control data into an analog attenuation control signal and outputs the same to the variable attenuator 58. Therefore, in order to correct the transmission power error, the transmission / reception control unit 43 measures the transmission power through the voltage detection value of the transmission RF signal output from the detection unit 42, calculates the traffic data output from the channel element 31, And calculates the transmission power to be outputted to the transmission antenna 37. [ The data for calculating the transmission power include a digital gain of a pilot channel, a digital gain of a synchronization channel, a digital gain of a paging channel, a digital gain of each traffic channel, a voice activity of each traffic channel, and a gain of a base station transmitter. In the above values, the gain of the base station transmitter, the digital gain of the pilot channel, the digital gain of the synchronization channel, and the digital gain of the paging channel are constants set in the base station setting. Values except for the base station gain, the digital gain of the pilot channel, the digital gain of the synchronization channel, and the digital gain of the paging channel are transmitted to the transmission / reception main part 34 of each sector in the channel element 31, And transmits the data for each frequency to the transmission / reception control unit 43. At this time, the calculation of the transmission power is calculated according to the following equation (1).

In Equation (1), PiG is the pilot channel digital gain of the pilot channel, SyG is the pilot channel digital gain of the synchronization channel, PaG is the paging channel digital gain of the paging channel, TG is the traffic channel digital gain of the traffic channel, VA is the traffic channel voice activity of the traffic channel, and TxG is the RF gain of the base station transmitter. Thereafter, the calculated transmission power is compared with the actually detected transmission power to obtain an error, and a value corresponding to the error is output as attenuation control data.

As described above, in the method of tracking and correcting the transmission power of the transmitter according to the embodiment of the present invention, the power detector 42 independent from the transceiver 35 is installed and control is performed by the transmission / reception controller 43 of the corresponding transceiver unit. At this time, the power detector 42 measures only the transmission power of each transceiver 35 and uses the corresponding local frequency of the transceiver 35, which simplifies the hardware and facilitates the hybrid IC. In addition, since the control for each transmission frequency is integrated, the information movement between the controllers can be reduced, and the tracking loop of the transmission power can be executed quickly.

5 is a flow chart illustrating a method for tracking and compensating for transmit power in an embodiment of the present invention. Referring to FIG. 5, the channel element and system interface controller 31 inputs traffic information output from the channel element 32, processes the processed traffic information for each sector, and outputs the traffic information to the transmission / reception main controller 34 through a system communication line. Then, the transmission / reception main controller 34 processes the traffic information output from the channel element and the system interface controller 31 into frequency-specific data and outputs the processed traffic information to the corresponding transmission / reception controller 43. Then, the transmission / reception control unit 43 receives the frequency-dependent data in step 511, and calculates transmission power to be theoretically output according to the equation (1) and the calculation formula in step 513. In Equation (1), the RF gain of the base station transmitter, the digital gain of the pilot channel, the digital gain of the synchronization channel, and the digital gain of the paging channel are fixed values, And the values are transferred from the channel element 32. The transmission power value calculated by Equation (1) is used as a reference value for adjusting the gain of the transmitted RF signal.

After calculating the theoretical transmission power value as described above, the transmission / reception control unit 43 receives the voltage of the transmission RF signal output from the power detector 42 in step 515 and obtains the actually measured transmission power. In step 517, the transmission / reception controller 43 compares the actually measured transmission power with a reference transmission power value to calculate an error. At this time, if the two transmission power values are equal to each other, the transmission / reception control unit 43 detects it in step 519 and maintains the attenuation control data as it is, and returns to step 511 to prepare for the next operation. This means that the gain control of the transmission RF signal, which is currently adjusted by the variable attenuator 58, is in a normal state. However, if the two transmission power values are different in step 519, the transmission / reception controller 43 detects that the error is generated in step 519, and outputs the attenuation control data for correcting the corresponding error magnitude in step 521. [ Then, the D / A converter 65 of the transmission / reception control unit 43 converts the attenuation control data into an attenuation control signal and applies the attenuation control signal to the variable attenuator 58.

When the attenuation control signal is converted, the variable attenuator 55 increases / decreases the transmission gain of the up-converted RF signal according to the converted attenuation control signal, and thus the transmission power of the RF signal output through the transmission antenna 59 also increases Lt; / RTI > Then, the transmission / reception control unit 43 repeats the operation shown in FIG. 5 and outputs the attenuation control data for controlling the variable attenuator 55 until the transmission power of the adjusted transmission RF signal has the same value as the set transmission power.

In the transmission power tracking and correction method as shown in FIG. 5, theoretical transmission power is first calculated, and then the actually measured transmission power is received and compared. However, after the actual measured transmission power is received, It can be seen that the same effect can also be achieved in the order of calculating.

As described above, when tracking and correcting the transmission power in the mobile communication system according to the embodiment of the present invention, a power detector is installed in each transceiver, and the transmission / reception controller of the mobile communication system compares the measured transmission power with the reference transmission power And corrects the transmission gain by the generated error magnitude. Therefore, it is possible to perform a transmission power tracking loop, which is an important factor in capacity optimization in a mobile communication system, in a simple and quick manner, thereby improving the performance of the overall system.

Claims (3)

A transmission apparatus of a mobile communication system, A channel element for generating digital gain information per channel, Transmitters for generating a RF transmission signal by up-converting the signal in the channel element and adjusting the gain of the transmission signal by the variable attenuator based on the attenuation control data; Directional couplers connected to output terminals of the corresponding transmitters, respectively, A power detector for detecting transmission powers of the respective transmitters coupled in the directional couplers, Calculating a reference transmission power according to Equation (11) according to channel gain information output from the channel element, receiving actual transmission power output from the power detector, and comparing two transmission power values, And a transmission / reception controller for controlling the variable attenuator to increase / decrease the transmission power of the transmitter by an error amount when the difference is different. &Quot; (11) " . In Equation (11), PiG denotes a digital gain of a pilot channel, SyG denotes a digital gain of a synchronization channel, PaG denotes a digital gain of a paging channel, TG denotes a digital gain of a traffic channel, VA denotes a voice activity of a traffic channel, RF gain. 2. The apparatus of claim 1, A mixer for mixing an output of the directional coupler and a local frequency of the transmitter; A filter for detecting a transmission signal component by filtering the down-converted signal from the output of the mixer, And a detector for converting an output of the filter into an envelope detection voltage and outputting the envelope voltage to the transmission / reception control unit as transmission power. A transmission power tracking and correction method of a mobile communication system including a transmitter having variable attenuation and a circuit for detecting transmission power of the transmitter, Receiving channel gain values output from the channel element and calculating a reference transmission power value according to Equation (12) Comparing the actual transmission power value output from the detection circuit with the transmission power value calculated by Equation (12) And varying the gain of the transmitter by obtaining an error value when the two transmission power values are different from each other in the comparing step. &Quot; (12) " . In Equation 12, PiG denotes a digital gain of a pilot channel, SyG denotes a digital gain of a synchronization channel, PaG denotes a digital gain of a paging channel, TG denotes a digital gain of a traffic channel, VA denotes a voice activity of a traffic channel, RF gain.