KR20040041202A - Method for comprising of look up table about pdm code in mobile station - Google Patents

Abstract

PURPOSE: A method is provided to build an accurate lookup table by effectively selecting sample values of the lookup table and calculating an optimum PDM(pulse density modulation) code. CONSTITUTION: A method comprises a step(S300,S310) of determining the maximum value and the minimum value for the power level for building a PDM code lookup table, dividing the ranged between the maximum value and the minimum value into plural sections, and selecting the determined maximum value and the minimum value and values for discriminating the sections as a sample value; a step(S320) of selecting the PDM codes corresponding to the sample values for the selected power level; a step(S330) of measuring power for each of PDM codes from one or more mobile communication terminals by using the selected PDM codes; a step(S340 to S370) of calculating an average value of the measured values, and calculating a linear equation by using the average value; and a step(S380) of building a PDM code lookup table by calculating PDM code values for predetermined values of the power level by using the linear equation.

Description

METHODO FOR COMPRISING OF LOOK UP TABLE ABOUT PDM CODE IN MOBILE STATION}

The present invention relates to a method for configuring a PD code lookup table in a mobile communication terminal. The present invention relates to a PD code lookup table in a mobile communication terminal that efficiently selects sample values constituting the table and calculates an optimal PD code. It relates to how to configure.

In general, a terminal of a wireless communication system such as a code division multiple access (CDMA) scheme or a personal communication services (PCS) scheme transmits a radio frequency (RF) signal through an antenna. Receive a signal from a base station via an antenna. For this transmission and reception operation, a power amplifier is provided at a transmission end of a wireless communication terminal as is well known.

The power amplifier occupies a large proportion in the characteristics and power consumption of the system. The power amplifier is not always driven at the maximum transmission power, but the transmission power level varies according to the distance from the base station and the moving speed of the user. When the distance between the base station and the wireless communication terminal is close, that is, when the strength of the received signal is large, the output power level of the power amplifier is relatively decreased. On the other hand, when the wireless communication terminal moves to the furthest place within the cell radius, that is, when the strength of the received signal is small or the user's moving speed increases, the power amplifier has a high frequency signal close to the maximum output power level. Will be sent.

1 is a view showing the configuration of a control device for a power amplifier according to the prior art. The control device as described above is characterized in that the bias is continuously controlled in order to obtain the maximum efficiency according to the output level.

Referring to FIG. 1, a control device of a power amplifier includes a variable power supply 101, a first power amplifier 1 (PA1) 102, a PA2 103, a controller 104, and received signal strength. (RSSI; Received Strength Signal Indicator) detection unit 105. The RSSI detector 105 detects the strength of the received signal and outputs the detection result to the controller 104. The controller 104 inputs the detection result by the RSSI detector 105, and outputs a signal Vbias_cntl for controlling the current of the power amplifier and a signal for controlling the voltage. In addition, the controller 104 is output as a signal for controlling an AGC amplifier (not shown). Operations through the above configuration are well known techniques and will be omitted.

On the other hand, the control unit 104 may be configured as shown in FIG.

Referring to FIG. 2, the controller 104 may include RAMs 201 and 202 and pulse density modulation (PDM) signal generators, which are power amplifier look-up tables (PALUTs). 203 and 204, a transmission gain limiter (TX_GAIN_LIMIT) 205, a closed-loop power control value storage unit 206, and an adder 207.

The output of the transmission gain limiter 205 is applied to the first lookup table 201 and the second lookup table 202, and each of the lookup tables 201 and 202 is connected to the transmission gain limiter 205. Output the value corresponding to the output. The lookup tables 201 and 202 store output values corresponding to a series of input values, and output digital values for controlling the current of the power amplifiers.

More specifically, the PDM code lookup tables store PDM code values corresponding to each output value in order to generate a PDM signal for controlling the bias voltages of the power amplifiers. In addition, the power level output by setting the input PDM code value may output different values for each terminal due to characteristics of each terminal and various other factors.

For example, the Rx AGC PDM code and the Tx AGC PDM code are represented by the output of a digital analog converter (DAC) from a modem chip. If the bit of the signal output from the DAC is 10 bits, the number is 2 ^{10 bits} = 1024 and varies from 0 to 1024. The PDM code of the modem chip is consistent, but when the power is adjusted by adjusting the AGC of Rx and Tx by receiving the PDM at the RF (Radio Frequency) terminal of the terminal, the characteristics of the components are not the same, so the same PDM code is called. Even though not all terminals have the same power, the RF is not adjusted.

On the other hand, in the actual terminal mass production process, the power of the terminal is measured at a certain power level, and if the predetermined power level does not come out, the power level of the terminal is adjusted by giving an appropriate offset to the PDM code. In this case, the error range of the initially generated PDM code lookup table may be large, and the accuracy of the unmeasured power level value may not be reliable. In addition, there may be a problem in the accuracy of the power level due to the offset.

Therefore, conventionally, PDM codes were measured for each Rx and Tx power level in order to construct a PDM code lookup table. In the above work, if the interval between power levels to be measured is narrowed for accurate power level measurement, the time required for measurement is further increased, and the number of terminals to be reflected in the measurement is limited due to the increase in the measurement time.

Since the purpose of the PDM code lookup table is to construct the most optimal table statistically, if the number of measurement terminals is reduced, the reliability of the PDM code is also reduced. On the other hand, if an error occurs in the PDM code, the error of the power level increases, and the development and mass production of the problem of increasing the time and cost to meet the power level.

Accordingly, an object of the present invention relates to a method for efficiently constructing a PDM code lookup table, which predicts the accuracy of a power level measured by a sample using Monte Carlo Mothod, and the power measured by the sample. A method of constructing a PDM code lookup table using Monte Carlo method in a mobile communication terminal which makes a statistically more accurate PDM code lookup table by forming a linear equation that maintains the linearity of the lookup table using a level and a PDM code In providing.

The present invention for achieving the above object, in the method for configuring a PD code lookup table in a mobile communication terminal, determining the maximum value and the minimum value of the power level used in the configuration of the PD code lookup table, Dividing the range between the maximum value and the minimum value of the power level into one or more sections, selecting the determined maximum value, the minimum value and the values separating the sections as sample values, and sample values of the selected power level. Selecting the corresponding PD codes, measuring the power of each PD code from one or more mobile communication terminals by using the selected PD codes, and measuring the respective PD codes The average value is calculated from the values, and the linear domain linear equation is calculated using the average values of the calculated PDMS codes. Shipping is characterized in that by the process and, the calculated equation progress, including the step of configuring the Phi DM DM code look-up table to calculate the code values for the predetermined value of the power level.

When calculating the average value from the power measured values for each PD code, the average and the variance of power values in each measured PD code are calculated, and only the measured values within a predetermined error range among the measured values It is characterized in that for calculating the average value.

The process of selecting the PD codes corresponding to the sample values of the selected power level may be selected as a value measured from a predetermined terminal extracted as a sample.

The method for dividing the range between the maximum value and the minimum value of the power level into predetermined sections is characterized in that the range is divided to be equally spaced.

The PD code lookup table is a lookup table for transmission power control or a lookup table for reception power control.

The PD code lookup table is a lookup table for transmitting baseband automatic gain control or a lookup table for receiving baseband automatic gain control.

1 is a block diagram showing the configuration of a power amplifier control apparatus according to the prior art.

2 is a diagram illustrating a configuration of a controller including a PD code lookup table according to the related art.

3 is a flowchart illustrating a method of constructing a PD code lookup table according to an embodiment of the present invention.

Figure 4 is a procedure showing a method of calculating the equation of the straight line using the Monte Carlo method according to an embodiment of the present invention.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. In the following description of the reference numerals to the components of the drawings it should be noted that the same reference numerals as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or a chip designer, and the definitions should be made based on the contents throughout the present specification.

According to the Monte Carlo method applied to the present invention, first, N independent sample terminals are selected by randomly selecting a terminal to be used as a sample. The power level measured by the independent sample terminal does not affect each value, and indicates how much the distribution of the measured power levels of the N terminals is distributed from the average value.

The average and the variance are calculated using the power level and PDM code values measured at each sample terminal, and the values outside the variance range are excluded. The selected PDM code and power level are used to form a straight line equation using Fitting a straight line. Since the power level of the terminal is operated in a linear region within a dynamic range, the linearity of the PDM code operating range of the sample terminal, which is an assumption for making a linear equation, is satisfied.

Hereinafter, a method of configuring a PDM code lookup table using the actual measured value and the Monte Carlo method according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 and 4.

The PDM code lookup table may be applied for power control on the transmit (Tx) and receive (Rx) side or for baseband auto gain control (AGC). The structure of this relatively complicated transmission side PDM code lookup table will be described. On the other hand, it is obvious that the same method as the method described later also applies to the receiving side PDM code lookup table.

First, a dynamic range of a transmission power level is selected from +21 dBm (minimum value) to -50 dBm (maximum value) (S300), and a point to be measured by one sample terminal is arbitrarily selected (S310). For example, if five points including the minimum and maximum values of the power level are selected, the dynamic range 71dBm / 4 = 17.75dBm. Therefore, the positions of the five points to be measured are -50dBm and -32.25dBm. , -14.5dBm, 3.25dBm and 21dBm.

Next, when the PDM code at the point where the transmission power is output is selected by using a predetermined sample terminal (S320), it is possible to express in the form of coordinates such as (transmission power, PDM code). If the selection result is configured as (-50, 330), (-32.25, 457), (-14.5, 584), (3.25, 720) and (21, 841), the PDM code values 330, 457, 584, 720, and 841 are fixed values.

The power level is measured by inputting the determined PDM code values to all the measurement target terminals (S330). If four terminals are measured, the power level and the coordinate values of the PDM code are represented as shown in Table 1 below. Can be.

Sample terminal (Tx power (dBm), PDM Code) #One (-49.66, 330) (-32.35, 457) (-15.11, 584) (3.57, 720) (20.27, 841) #2 (-50.15, 330) (-33.45, 457) (-16.27, 584) (2.58, 720) (19.30, 841) # 3 (-49.52, 330) (-31.99, 457) (-14.66, 584) (4.31, 720) (20.91, 841) #4 (-48.74, 330) (-31.43, 457) (-13.93, 584) (4.58, 720) (20.59, 841)

For each PDM code, the above-described Monte Carlo method is applied to calculate an average value and a variance (S340), and values outside the calculated variance range are excluded from values for forming a linear equation (S350).

Dispersion according to the Monte Carlo method is shown in Equation 1 below.

In Equation 1, 'N' is the number of sample terminals, which is 4 according to <Table 1>, and 'P' is a power level of the corresponding PDM code. Referring to Table 1 and Equation 1, when the PDM code is '330', the variance σ is 0.256 and the average E is −49.51 dBm. At this time, the values of -48.74dBm of the # 4 sample terminal and -16.27dBm of the # 2 sample terminal outside of the range of E ± σ are less likely, so the values of the linear equations are excluded. On the other hand, when the PDM code is '457', the variance σ is 0.544 and the average E is -32.31 dBm. In the same way, -31.43dBm of the # 4 sample terminal and -33.45dBm of the # 2 sample terminal outside the range of E ± σ are excluded.

In addition, when the PDM code is '584', the variance σ is 0.721 and the average E is -14.99 dBm. -13.93dBm of the # 4 sample terminal and -16.27dBm of the # 2 sample terminal outside the range of E ± σ are excluded. When the PDM code is '720', the variance σ is 0.6 and the average E is 3.76 dBm. 4.58dBm of the # 4 sample terminal and 2.58dBm of the # 2 sample terminal outside the range of E ± σ are excluded.

Finally, when the PDM code is '841', the variance σ is 0.363 and the average E is 20.27 dBm. 20.91dBm of the # 3 sample terminal and 19.3dBm of the # 2 sample terminal outside the range of E ± σ are excluded.

In the above, since the excluded values are # 2 and # 4 or # 2 and # 3 terminals, when the average value is obtained as the power level of the # 1 and # 3 or the # 1 and # 4 terminals (S360), a final equation can be obtained. It is the value of five points. Therefore, the final values obtained as the average values are (-49.59, 330), (-32.17, 457), (-14.89, 584), (3.94, 720), and (20.43, 841).

The linear equations of the power level and the PDM code are obtained using the selected five points (S370). Four values of Equation 2 are first obtained to obtain the linear equations.

, , ,

In Equation 2, m = 5, x is a power level, and y is a PDM code value.

If y = ax + b, the linear equation can be used to construct a 2x2 matrix as shown in Equation 3 using Equation 2 above, and the solutions of the matrix are 'a' and 'b' Value.

Hereinafter, a method of calculating a linear linear equation using the matrix will be described in detail with reference to FIG. 4. First, as described above, the linear linear equation y = ax + b is defined (S400). A sample measurement point value (data point) m is selected (S410), and the sum of x and the sum of x ² are calculated (S420). Further, the sum of y and the sum of x x y are calculated (S430), and a normal equation matrix (2 x 2) is constructed (S440).

A unique solution of the constructed matrix is calculated (S450), and the linear solution equation is determined (S460) by substituting the calculated solution for the 'a' and 'b' values.

The values calculated by applying the data values of Table 1 to Equation 3 have a value of 'a' of 7.29 and a value of 'b' of 691.85.

Therefore, the final calculated linear equation is Becomes

Finally, a PDM code lookup table is configured by substituting the calculated linear equations into the respective power level values (S380), and the PDM code lookup table finally calculated by the values is shown in Table 2 below.

Tx power (dBm) PDM Code Tx power (dBm) PDM Code Tx power (dBm) PDM Code Tx power (dBm) PDM Code 21 845 3 714 -15 583 -33 451 20 838 2 706 -16 575 -34 444 19 830 One 699 -17 568 -35 437 18 823 0 692 -18 561 -36 429 17 816 -One 685 -19 553 -37 422 16 808 -2 677 -20 546 -38 415 15 801 -3 670 -21 539 -39 408 14 794 -4 663 -22 531 -40 400 13 787 -5 655 -23 524 -41 393 12 779 -6 648 -24 517 -42 386 11 772 -7 641 -25 510 -43 378 10 765 -8 634 -26 502 -44 371 9 757 -9 626 -27 495 -45 364 8 750 -10 619 -28 488 -46 357 7 743 -11 612 -29 480 -47 349 6 736 -12 604 -30 473 -48 342 5 728 -13 597 -31 466 -49 335 4 721 -14 590 -32 459 -50 327

As described above, the PDM code lookup table is not only applied to the illustrated transmit power PDM code lookup table, but the same method may be applied to a received power PDM code lookup table and a transmit / receive baseband AGC lookup table.

That is, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

As described above, the present invention can construct a more accurate lookup table when viewed statistically, and obtain a larger amount of measurement samples while maximally saving time for measurement. In addition, since a more accurate lookup table can be configured, the accuracy of the power level controlled by the PDM code is guaranteed.

Claims (8)

In the method for configuring a PD code lookup table in a mobile communication terminal, Determine a maximum value and a minimum value of a power level used to construct the PD code lookup table, and divide a range between the maximum value and the minimum value of the power level into one or more sections to determine the determined maximum value, minimum value, and the Selecting the values separating the intervals as sample values, Selecting PD codes corresponding to sample values of the selected power level, Measuring power of each PD code from one or more mobile communication terminals by using the selected PD codes; Calculating an average value from the measured values in each PD code, and calculating a linear domain linear equation using the calculated average values in each PD code; Comprising a process of configuring a PD code lookup table by calculating PD code values for the predetermined values of the power level according to the calculated equation using the Monte Carlo method in the mobile communication terminal How to configure a PDM code lookup table. The method of claim 1, When the average value is calculated from the measured values of the power for each PD code, The Monte Carlo method in the mobile communication terminal is calculated by calculating the average and the variance of the power values in each measured PD code, and selecting only the measured values within a predetermined error range among the measured values. How to construct a PD code lookup table using The method of claim 1, The process of selecting PD codes corresponding to the sample values of the selected power level is performed by using a Monte Carlo method in the mobile communication terminal, characterized in that the selected value is measured from a predetermined terminal extracted as a sample. How to organize code lookup tables. The method of claim 1, In the method for dividing the range between the maximum value and the minimum value of the power level into predetermined sections, the range is divided into equal intervals. The PD code lookup table using the Monte Carlo method in the mobile communication terminal. How to configure. The method of claim 1, And the PD code lookup table is a look-up table for transmission power control, and uses the Monte Carlo method to construct a PD code lookup table. The method of claim 1, And the PD code lookup table is a look-up table for receiving power control, and configures a PD code lookup table by using the Monte Carlo method. The method of claim 1, And the PD code lookup table is a look-up table for transmitting baseband automatic gain control, and uses the Monte Carlo method to configure the PD code lookup table. The method of claim 1, And the PD code lookup table is a lookup table for receiving baseband automatic gain control, and uses the Monte Carlo method to configure the PD code lookup table.