WO2011088680A1

WO2011088680A1 - Method and device for determining cubic metric and maximum power reduction

Info

Publication number: WO2011088680A1
Application number: PCT/CN2010/076613
Authority: WO
Inventors: 郭阳; 禹忠
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-01-21
Filing date: 2010-09-03
Publication date: 2011-07-28
Also published as: CN102136856A

Abstract

The present invention provides a method for determining a cubic metric. The method includes: obtaining the value of an initial cubic metric according to the following equation: (I), and outputting the initial cubic metric as the cubic metric, wherein CM represents the initial cubic metric, K is a constant, K>0, (II), (III), x' represents the conjugate transpose of the vector x, the length of x is N=1, v(t) is the input signal of the power amplifier, (IV), (V), and vref(t) represents the reference signal of the power amplifier. The present invention also provides a method for determining the maximum power reduction.

Description

Method and device for determining cubic measure and maximum back-off power

Technical field

The present invention relates to the field of radio frequency testing technologies for wireless communication products, and in particular, to a method and apparatus for determining a cubic metric and a maximum backoff power suitable for an LTE (Long Term Evolution) system.

Background technique

With the development of modern industry, all kinds of wireless communication products can only guarantee the communication quality if they have good transmitting and receiving performance. In wireless communication systems, two metrics are used to examine the effects of transmission techniques on the nonlinearity of the upstream power amplifier, namely PAPR (Peak to Average Power Ratio) and CM (Cubic Metric). In the past, the power processing performance of a power amplifier was evaluated by PAPR, that is, under the premise of a given power amplifier, the average power performance of the power amplifier decreased as the PAPR increased. Recent tests have shown that PAPR does not adequately describe the output performance of a power amplifier. Another parameter can be used to describe the output performance of a power amplifier, which is the CM. LTE finalizes CM is the most accurate way to measure the power efficiency of a power amplifier, which has an impact on the choice of related technologies, including uplink transmission and modulation.

The power backoff method is to compress the output power of the power amplifier from the ldB compression point (the amplifier has a linear dynamic range. In this range, the output power of the amplifier increases linearly with the input power. As the input power continues to increase, the amplifier gradually enters. In the saturation region, the power gain begins to decrease. Usually, the output power value when the gain is reduced to ldB lower than the linear gain is defined as the ldB compression point of the output power, expressed by PldB.) Backward 6-10 decibels, working far away Below the level of the ldB compression point, the power amplifier is moved away from the saturation region into the linear operating region, thereby improving the third-order intermodulation coefficient of the power amplifier. In general, when the fundamental power is reduced by ldB, the third-order intermodulation distortion is improved by 2 dB.

In actual use by various manufacturers, the power backoff is to take the output power of the power amplifier from the reference point (the reference point should be the maximum transmit power, because each family does not strictly use the ldB compression point as the maximum transmit power.) Backward retreat Decibels. The amount of backlash is closely related to the size of the CM value.

The power back-off method is simple and easy to implement, and does not require any additional equipment. It is an effective way to improve the linearity of the amplifier. However, when the power falls back to a certain extent, when the third-order intermodulation is reached Continuing the retraction below -50dBc will no longer improve the linearity of the amplifier, so it is necessary to determine the appropriate back-off power. MPR (Maximum Power Reduction) is the amount of power that needs to be rolled back. The size of the MPR depends on the value of the CM, and how the MPR is obtained by the CM is not yet determined in the prior art.

Summary of the invention

The present invention provides a method and apparatus for determining a cubic measure and a maximum back-off power.

In order to solve the above problems, the present invention provides a method for determining a cubic metric, comprising: obtaining an initial cubic metric value according to the following equation, and outputting the initial cubic metric value as a cubic metric:

201 _0§10 {歴( ))}- r .

CM:

K where CM denotes the initial cubic metric value, K is a constant, K>0, rms(x) = JV^ N- v _norm (t) = ^{1 1} , , x' denotes the conjugate transpose of the vector ,, N Indicates the length of the vector X, N= l,

Rms(v(t))

II represents the absolute value, O is the input signal of the power amplifier, ref _dB - vref ',

20log _w {rm _S (vref _orm (t))} , where

¹ , / (t) represents the rms rej (t) of the power amplifier

Reference signal.

For long-term evolution systems, K can be 1.56; for wideband code division multiple access systems, K can be 1.85.

The method of the present invention may further comprise:

Before outputting the cubic metric, the initial cubic metric value is added to the bandwidth compensation factor to obtain the corrected cubic metric value, and the corrected cubic metric value is output as the cubic metric, that is: CA^CM + C where the corrected cubic metric value is the bandwidth Compensation factor. The method may further include: before outputting the cubic metric, performing the following processing on the corrected cubic metric value to obtain a rounded metric value, and outputting the rounded cubic metric value as a cubic metric, ie: CM _fina i =CEIL{CM where CM _Flunal is the integer cube metric value, G is the unit of the up carry, and the CEIL operation is the value of the upward value of G. The method may further include: before outputting the cubic metric, performing the following processing on the initial cubic metric value CM to obtain a rounded cubic metric value, and outputting the rounded cubic metric value as a cubic metric, ie: CM _flnal =CEIL{CM,G} Where CM^ is the integer cubic metric value, G is the unit of the upward carry, and the CEIL operation is the operation of taking the value up by G.

The present invention also provides a method for determining a maximum back-off power, comprising: determining a maximum back-off power as a cubic metric and a constant A when the difference between the cubic metric and a constant A is not less than 0 after determining the cubic metric according to the method of the present invention. The difference, when the difference between the cubic metric and the constant A is less than 0, determines that the maximum back-off power is 0, where A is a constant and 0 < A < 5.

A can be 1 or 1.2.

The present invention also provides a cubic metric determining apparatus, the apparatus comprising an initial calculating unit configured to obtain an initial cubic metric value by outputting the initial cubic metric value as a cubic metric:

201 _0§10 {歴( ))}- r .

CM:

K where CM is the initial cubic metric value, K, K>0, rms(x) = A^^- , v _norm (t)-.

Ν rms(v(t)) χ' denotes the conjugate transpose of vector x, N denotes the length of vector X, N=l, II denotes the absolute value, ) is the input signal to the power amplifier, re = 20log _w {rm _S (vref _orm (t))} ,

) = ^{jWej < |} , m^(t) represents the reference signal of the power amplifier,

Rms(vref (t))

The apparatus of the present invention may further include: a correction unit connected to the initial calculation unit and configured to add the initial cubic metric value and the bandwidth compensation factor to obtain a corrected cubic metric value, and the obtained corrected cubic metric value is used as a cube The measurement output, namely: G^^GM + C^ where CM is the corrected cubic metric value and is the bandwidth compensation factor. The apparatus may further include: a rounding unit, the rounding unit is connected to the initial calculating unit and/or the correcting unit, and is configured to perform the following processing on the initial cubic metric value CM or the corrected cubic metric value to obtain a rounded cubic metric value CM, , will take the cube value CM. , as a cubic measure output: CM _flnal = CEIL{CM , G ^CEIL{CM

Where CM is the integer cubic metric value, G is the unit of the upward carry, and the CEIL operation is G The operation of the unit up value.

The apparatus of the present invention may further include: a rounding unit, the rounding unit is connected to the initial calculating unit, and is configured to perform the following processing on the initial cubic metric value to obtain a rounding metric value CM^, which will take the whole cubic metric value CM ^ As the cubic metric output: CM _flna i = CEIL{CM, GY, where CM is the integer cubic metric value, G is the unit of the upward carry, and CEIL operation is the upward value of G.

The present invention also provides a maximum back-off power determining device, where the device includes a cubic metric determining module and a maximum back-off power determining module, where

The cubic metric determination module is configured to determine a cubic metric according to the method of the present invention;

The maximum back-off power determining module is connected to the cubic metric determining module, and is configured to determine a maximum back-off power by: subtracting a cubic metric from a constant A to obtain a difference, when the difference is not less than 0 The maximum back-off power is determined as the difference between the cubic metric and the constant A. When the difference is less than 0, the maximum back-off power is determined to be 0, where 0<A<5.

A can be 1 or 1.2.

The present invention provides a method and apparatus for determining a cubic metric and determining a maximum back-off power based on a cubic metric, capable of determining a maximum back-off power and improving power amplifier efficiency.

BRIEF abstract

The drawings are intended to provide a further understanding of the invention, and are intended to be a part of the description of the invention.

1 is a flowchart of a method for calculating an MPR according to an embodiment of the present invention;

2 is a block diagram of a cubic metric determining apparatus according to an embodiment of the present invention;

FIG. 3 is a block diagram of a maximum back-off power determining apparatus according to an embodiment of the present invention.

Preferred embodiment of the invention

The present invention provides a method for determining a cubic measure, and is specifically referred to the first method to the fourth method of the embodiment. method one Calculate the initial cubic metric value according to the following formula, and use the initial cubic metric value as the cubic metric:

In the equation (1 - 1) is the normalized voltage waveform of the input signal, e/ is the normalized voltage waveform of the reference signal (12.2 kbps AMR Speech), where: rms{x) =

x' denotes the conjugate transpose of vector x, N denotes the length of vector x, N=l in this method, II denotes absolute value, 0 is the input signal of power amplifier, m^(t) denotes reference signal of power amplifier ; Among them, 201o _gl . {r wish|r _e / _m (t)|} is a constant term, and the constant term can be named ^, ie =

The preferred value of ^ is 1.52, then the basic formula of CM can be transformed into the following formula:

2. Log ₁₀ {履|v. (t)|}- ref _dB

CM-

K ; (1-2)

For the constant Κ, Κ > 0 in the above formula, the preferred values given by the present invention are: For LTE systems, the preferred value for Κ is 1.56; for W-CDMA systems, the preferred value for Κ is 1.85.

Method Two

The initial cubic metric value can be corrected by modifying the CM for the different bandwidths that are applied to obtain the corrected cubic metric value and outputting the corrected cubic metric value as a cubic metric:

, ²⁰¹ °§10 {履^V orm (0

CM = I" ref _dB

+ C _dB ; (2) where is the bandwidth compensation factor for different bandwidths.

In general, the preferred value is 0, the preferred value for the 3.84 MHz bandwidth is 0; the preferred value for the 4.51 MHz bandwidth is 0.77; other values are also within the scope of the present invention. Method three

In some cases, it is not desirable to process multiple digits after the decimal point of the CM value. It is desirable to perform the following processing on the value of the CM, and round the initial cubic metric value to obtain a rounded cube metric value as a cubic metric. Output, see the following formula:

Where G is the unit of the upward carry. The preferred value of G is 0.5; 0.1; 0.2; 0.3; 0.4.

The CEIL operation takes the value up in G.

Taking G as 0.3 as an example, the value of CM is [0, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8, ..., xia], where CM is the maximum value that CM can take, and the value of CM is to be determined.

For example, the value of CM is 1.0. After CEIL, the value of CM is 1.2.

Method four

Combining method 2 and method 3, method 4 can be obtained. As shown in the following formula, the corrected cubic metric value is rounded to obtain a rounded cubic metric value, and the rounded cubic metric value is used as a cubic metric value.

The meaning of each symbol is as described above.

The parameters in each expression have the same meaning, and the preferred values are the same, and can be applied to each other. The present invention also provides a method for determining MPR. After determining CM according to method one, two, three or four, when the difference between CM and a constant A is not less than 0, the maximum back-off power is the difference between CM and constant A. When the difference between CM and constant A is less than 0, the maximum back-off power is 0, where A is a constant and 0 < A < 5. It can be expressed by the following formula: MPR=MAX(CM-A, 0), that is, when CM-A is not less than 0, CM-A is output as the maximum back-off power, and when CM-A is less than 0, output 0 is the maximum back-off. power. Wherein A is a constant, 0 < A < 5, and a preferred value of A is 1 or 1.2.

The method for determining the MPR after determining the CM according to the method 4 is as shown in FIG. 1 , including: Step 110, first calculating the initial cubic metric, as follows

20 log ₁₀ {calendar

CM = - IV _m (t)|} - ref _m ·

K

Step 120, correcting the initial cubic metric, and obtaining

Step 130, rounding CM ₂ to obtain

Step 1 ⁴ 0, the maximum backoff power is obtained according to MPR=MAX(CM, -A, 0).

The present invention also provides a cubic metric determining device, as shown in FIG. 2, comprising an initial calculating unit, a correcting unit and a rounding unit, wherein:

The initial calculation unit is configured to obtain an initial cubic metric value according to the following formula, and output the initial cubic metric value as a cubic metric:

201 _0§10 {歴( ))} - r .

CM:

K where CM is the initial cubic metric value, K, ^ is a constant, Κ>0, rms(x) = _v 』= , x, which represents the conjugate transpose of vector x, Ν represents the length of vector X, this method rms (v(t))

Medium Ν=1, I I means absolute value, 0 is power amplifier input signal, =

20\og _w {rms(vref _m (t))} , vref _norm (t) = ¹ /, ,, m^(t) denotes the reference rmsi ref ( ) of the power amplifier

Signal; Preferably, for long term evolution systems, K is 1.56; for wideband code division multiple access systems, K is 1.85.

The correction unit is connected to the initial calculation unit, and is configured to add the initial cubic metric value and the bandwidth compensation factor to obtain a corrected cubic metric value, and output the corrected cubic metric value as a cubic metric:

CM _new = CM + C _dB ;

Where CM is the corrected cubic metric value and is the bandwidth compensation factor.

The rounding unit is connected to the initial calculating unit and/or the correcting unit, and is configured to perform the following processing on the initial cubic metric value CM or the modified cubic metric value 1 to obtain a rounded cubic metric value CM^ Describe the whole cubic metric value CM as the cubic metric output:

CM _flnal = CEIL {CM, G] or CEIL {CM _new , G];

Among them, CM^ is the value of the whole cubic metric, G is the unit of the upward carry, and the CEIL operation takes the value of G upward. The cubic metric determining means may include only the initial calculating unit, or only the initial calculating unit and the correcting unit; or only the initial calculating unit and the rounding unit.

The present invention further provides a maximum back-off power determining device, as shown in FIG. 3, including a cubic metric determining module and a maximum back-off power determining module, where

The cubic metric determination module is configured to determine a metric according to the method described in the method embodiment of the present invention;

The maximum back-off power determination module is connected to the cubic metric determination module, and is configured to: subtract the cubic metric from a constant A to obtain a difference, and when the difference is not less than 0, determine the maximum back-off power as a cubic metric and a constant The difference between A, when the difference is less than 0, it is determined that the maximum back-off power is 0, wherein 0<A<5. Preferably, the A is 1 or 1.2.

The above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Industrial applicability

Compared with the prior art, the present invention can determine the maximum back-off power and improve the efficiency of the power amplifier.

Claims

Claim

1. A method of determining a cubic measure, comprising:

The initial cubic metric value is obtained according to the following formula, and the obtained initial cubic metric value is output as a cubic metric:

201 _0§10 {歴( ))}- r .

CM:

Rms(v(t))

20log _w {rm _S (vref _orm (t))} , where vref _norm (t)= ¹ , /(t) denotes rms rej (t) of the power amplifier

Reference signal.

2. The method of claim 1 wherein K is 1.56 for a Long Term Evolution system and K is 1.85 for a Wideband Code Division Multiple Access system.

3. The method of claim 1 further comprising:

Before outputting the initial cubic metric value as a cubic metric, adding the initial cubic metric value to the bandwidth compensation factor to obtain a corrected cubic metric value, and outputting the corrected cubic metric value as a cubic metric, namely:

CM _new = CM + C _dB ;

4. The method according to claim 3, further comprising: before outputting the corrected cubic metric value as a cubic metric, performing the following processing on the corrected cubic metric value to obtain a rounded cubic metric value, and the rounding The cubic metric value is output as a cubic metric, ie:

CM _flnal =CEIL{CM _new ,G}; where CM^ is the integer cube metric value, G is the unit of the up carry, and the CEIL operation is the value of the upward value of G.

5. The method of claim 1 further comprising: using said initial cubic metric value as a cube Before measuring the output, the initial cubic metric value CM is processed as follows to obtain a rounded cubic metric value, and the rounded cubic metric value is output as a cubic metric, namely:

CM _flnal =CEIL{CM,G}- where CM^ is the integer cubic metric value, G is the unit of the upward carry, and the CEIL operation is the upward value of G.

6. A method for determining a maximum back-off power, comprising: determining a maximum back-off after determining a cubic metric according to the method of any one of claims 1 to 5, when a difference between the determined cubic metric and a constant A is not less than 0 The power is the difference between the cubic metric and the constant A; when the difference between the determined cubic metric and the constant A is less than 0, the maximum back-off power is determined to be 0; wherein A is a constant, and 0 < A < 5.

7. The method of claim 6, wherein the A is 1 or 1.2.

8. A cubic metric determining apparatus, comprising an initial calculating unit, wherein the initial calculating unit is configured to obtain an initial cubic metric value by the following formula, and output the obtained initial cubic metric value as a cubic metric:

201 _0§10 {歴( ))}- r .

CM:

) = ^{jWej < |} , m^(t) represents the reference signal of the power amplifier,

Rms(vref (t))

9. Apparatus according to claim 8 wherein K is 1.56 for a Long Term Evolution system and K is 1.85 for a Wideband Code Division Multiple Access system.

10. The apparatus of claim 8 further comprising a correction unit,

The correction unit is connected to the initial calculation unit, and is configured to add an initial cubic metric value obtained by the initial calculation unit to a bandwidth compensation factor to obtain a corrected cubic metric value, and the corrected cubic metric value is used as a cubic metric Output, ie:

CM _new = CM + C _dB ;

Where CM is the corrected cubic metric value and C _dB is the bandwidth compensation factor.

11. The apparatus of claim 10, further comprising: a rounding unit, the rounding unit being coupled to the initial computing unit and/or the modifying unit and configured to pair the initial cubic metric value or the corrected cubic metric value The following processing is performed to obtain a rounded cubic metric value CM, and the rounded cubic metric value CM _{flrud is} output as a cubic metric:

CM _flml = CEIL {CM, G] or CEIL {CM _new , G]; where CM^ is the integer cubic metric value, G is the unit of the upward carry, and the CEIL operation is the upward value of G.

12. The apparatus according to claim 8, further comprising: a rounding unit, wherein the rounding unit is connected to the initial calculating unit, and is configured to perform the following processing on the initial cubic metric value CM obtained by the initial calculating unit, to obtain The whole cubic metric value CM^ is taken, and the rounded cubic metric value CM^ is output as a cubic metric:

CM _flnal = CEIL{CM,G} - where CM^ is the integer cubic metric value, G is the unit of the up carry, and CEIL operation is the upward value of G.

13. A maximum back-off power determining device, comprising a cubic metric determining module and a maximum back-off power determining module, wherein

The cubic metric determination module is configured to determine a metric according to the method of any one of claims 1 to 5;

The maximum back-off power determining module is connected to the cubic metric determining module, and is configured to determine a maximum back-off power by: subtracting a cubic metric determined by the cubic metric determining module from a constant A to obtain a difference When the difference is not less than 0, the maximum back-off power is determined as the difference between the cubic metric and the constant A. When the difference is less than 0, the maximum back-off power is determined to be 0, where 0<A<5.

14. The apparatus according to claim 13, wherein said A is 1 or 1.2.