Background technology
Power control is one of core technology of Modern Mobile Communications Systems, its objective is to overcome near-far interference, makes system can keep high quality communication, other users that take same channel is not produced unnecessary interference again.
Power control is divided into downlink power control and up-link power control, and downlink power control is to adjust the base station to user terminal (UE, User Equipment) emitted power; Up-link power control is exactly the size of controlling the transmitting power of each user terminal, and it can be divided into open Loop Power control and closed power control.
The precondition of up link open Loop Power control is that hypothesis is up identical with the downlink transfer loss, portable terminal receives and measures the signal strength signal intensity that send the base station, and estimation downlink transfer loss, then according to this estimation, terminal is adjusted its transmitting power voluntarily, just received signal strengthens, and just reduces its puberty power; Received signal weakens, and just increases its transmitting power.Uplink closed loop is promptly detected the signal strength signal intensity or the signal to noise ratio of self terminal by the base station, compare with desired value according to recording the result, forms power control instruction (TPC, Transmit Power Control), and the notice terminal is adjusted its transmitting power.
Generally speaking, the power control system of terminal radio frequency circuit is made up of power amplifier, sender, Base Band Unit and 4 parts of memory, the performance number that Base Band Unit is exported from memory as required reads corresponding APC (Auto Power Control) control word, then with the signal of this APC control word control sender emission with the corresponding power of this APC control word, this signal is launched behind power amplifier, the storage format of APC control word APC table normally in the memory.
Usually APC control word and emitted power possess good linear relationship, but the physical characteristic owing to the employed device of terminal can not present perfect characteristic in the reality, mainly shows two aspects:
1. the gain of device such as sender, power amplifier or circuit has bigger discreteness, that is: different its gains of device are different;
The gain of device or circuit be with environmental condition particularly the variation of temperature and voltage change and its Changing Pattern is not an ideal linearity.
At these two characteristics of device, the prior art scheme has proposed corresponding solution: at discreteness, solve by the measure of every terminal all being produced calibration, calibration result adopts the form of APC calibration chart to deposit usually; And gain is subjected to the problem of environmental influence, except improving the characteristic of using device or circuit requires, adopt the compensating circuit of environmental factors such as increasing temperature, voltage, humidity to solve.
Figure 1A shows in the prior art scheme fundamental diagram that compensates by to temperature and voltage, this scheme increases temperature sensing circuit and voltage detecting circuit in terminal, make testing environment temperature and operating voltage that terminal can be real-time, improve accuracy rate terminal power control by compensation to temperature and voltage.Its to the key step of terminal power control shown in Figure 1B:
Step 101: when producing calibration, calibrate out the corresponding APC control word of all power grades at every station terminal, form an APC calibration chart, high-ranking officers are punctual simultaneously when calibration APC control word production calibration temperature and production calibration voltage are recorded in the APC calibration chart; And record the penalty coefficient C of temperature and voltage by experiment
1, C
2, also being recorded in the APC calibration chart, the content that writes down in the last APC calibration chart is as shown in table 1.
Step 102: terminal when operate as normal, testing environment temperature T regularly
1With voltage V
1
Step 103: Shu Chu power reads corresponding APC control word APC in the APC calibration chart as required
TABLEAnd corresponding production calibration temperature T
0With production calibration voltage V
0
Step 104: ambient temperature during computing terminal work and the difference DELTA T=T between voltage and production calibration temperature and the voltage
1-T
0With Δ V=V
1-V
0
Step 105: by the value of the APC control word behind following formula calculating carrying out temperature, the voltage compensation;
Step 106: the signal of launching corresponding power grade with the control of the APC control word after the compensation of calculating gained sender.
The APC calibration chart of table 1. prior art
This method is the compensation method of open loop, need do independent consideration to the factor of each influence gain, has increased temperature sensing circuit and voltage detecting circuit, if influencing factor is many more, compensate complicatedly more, the testing circuit of increase is also just many more, and the shared memory headroom of APC calibration chart is also just big more; In addition, because environmental factors such as temperature when needing each power grade calibration of test and voltages, the time that causes producing calibration is longer, and if consider that the factor of influence is many more, the time of producing calibration is long more.
Embodiment
Inserting (TD-SCDMA, Time Division-Synchronous Code Division Multiple Access) system terminal with TD SDMA in the present embodiment is that example describes.
Press 3G (Third Generation) Moblie collaborative project group (3GPP, 3rd Generation Partnership Project) standard, the TD-SCDMA terminal is as follows to the specific requirement of up-link power control:
1) UE peak power output
Table 2 has been listed the maximum nominal power output and the tolerance limit of different capacity tier definition.
Table 2.UE peak power output and tolerance limit
Power grade |
Peak power output |
Tolerance limit |
1 |
+30dBm |
+1dB/-3dB |
2 |
+24dBm |
+1dB/-3dB |
3 |
+21dBm |
+2dB/-2dB |
4 |
+10dBm |
+4dB/-4dB |
2) open Loop Power control
Open Loop Power control is that the UE transmitter is provided with the ability that its power output is a designated value.Table 3 has been listed the minimum tolerance limit requirement of open Loop Power control.
The minimum tolerance limit of table 3 open Loop Power control
Normal condition |
±9dB |
Extreme situation |
±12dB |
3) closed power control
Receive power control command (TPC_cmd at UE, Transmit Power Control Command) in the next time slot after, transmitter have changes the ability of its power output 1,2 or 3dB according to the numerical value of TPC or RP-TPC, and its minimum requirements is as follows:
The power output step-length scope of table 4 transmitter when using closed power control
The average output power step-length scope of table 5 transmitter when using closed power control
Power control command group (TPC_cmd group) is the combination of one group of power control command, and it can obtain according to a series of lasting power control command in the identical time.
4) transmitting power accuracy of measurement
Table 6 transmitting power accuracy of measurement
By above requirement as can be seen, in the TD-SCDMA terminal, lower to the requirement of up link open Loop Power control, the characteristic of device itself just can satisfy, and closed power control requires than higher, maximum transmission power and transmitting power accuracy of measurement is then allowed to exist the tolerance of certain limit.If terminal can not satisfy these requirements, then possibly can't test by RF consistency, further may influence testing protocol consistency.For making terminal satisfy these requirements, the embodiment of the invention proposes a kind of method and apparatus of terminal power control.
Engage Figure of description below, specific implementation process of the present invention is described.
Fig. 2 shows a kind of terminal structure schematic diagram of the embodiment of the invention, comprises power amplifier, sender, memory and signal processor.Wherein,
Memory except the corresponding relation that is used for storage power grade and power control signal, also is used for the corresponding relation of storage power detected value and power output.
These data that memory is preserved are to calibrate in the production of terminal to obtain.
In specific implementation process, power control signal is APC (Auto Power Control) control word, when producing calibration, the power amplifier of terminal sends the power of different brackets respectively, corresponding APC control word when obtaining each power controlling grade of emission is stored in each power grade and corresponding APC control word in the memory.
In order to make the relation between power grade and the APC control word satisfy linear relationship, can carry out linear fit to storage power grade and APC control word, the data after the match are kept in the memory.
The corresponding relation of power detection value and power output also obtains when producing calibration, the power detection value of preserving in the memory and the corresponding relation of power output can be each power output with its corresponding power detection value between relation, it also can be the characteristic of determining the relation between power detection value and the power output, because usually, should satisfy linear relationship between power detection value and the power output.For the previous case, can when producing calibration, allow terminal send the power of different brackets respectively, measure and preserve corresponding power detection value.For latter event, can select a benchmark power output and a reference output power, allow terminal send this two power respectively, measure two kinds of power detection values under the situation, thereby can draw the coefficient of determining the relation between power detection value and the power output.
Signal processor, be used to receive power adjustment instruction from the base station, detect by transmitting power described power amplifier emission, obtain the power detection value, according to the corresponding relation of described power detection value and power output, obtain the power output of described power detection value correspondence, and according to described power output and described power adjustment instruction, determine to want the emitted power grade next time, and send the power control signal of described power grade correspondence to described sender.
Further, described signal processor comprises: feedback circuit and Base Band Unit.Wherein,
Feedback circuit is connected with described power amplifier, is used for the transmitting power of described power amplifier emission is detected, and the power detection value that detection obtains is fed back to Base Band Unit;
Base Band Unit, be connected with described feedback circuit, be used to receive the power detection value that described feedback circuit sends, according to the power detection value of storage and the corresponding relation of power output, obtain the power output of described power detection value correspondence, and according to described power output, and the power adjustment instruction from the base station that receives, determine emitted power grade next time, and send the power control signal of described power grade correspondence to described sender.
And described feedback circuit further comprises: sample circuit and power-sensing circuit.Wherein,
Sample circuit is connected with described power amplifier, is used for that described power amplifier is connected the transmitting power of launching and takes a sample, and send the power of sampling to power-sensing circuit;
Power-sensing circuit is connected with sample circuit, is used to measure the power of described sample circuit sampling, and sends the power detection value that measures to Base Band Unit.
As can be known from Table 6, the scope of the transmitting power that need detect is about 10dB, and the performance number scope of power-sensing circuit can design about 20dB, and the scope of power detection value and detected emitting power grade can mate.
In specific implementation process, sample circuit and power-sensing circuit can have multiple implementation, such as, can use a directional coupler as sample circuit, use a diode as power-sensing circuit.
The idiographic flow of the method for a kind of terminal power control that the invention process provides mainly may further comprise the steps as shown in Figure 3:
Step 301: signal processor according to the indication of this power adjustment instruction and current power detection value, is determined emitted power grade next time when receiving from the power adjustment of base station instruction.
Concrete, step 301 can comprise:
Step 301a: from feedback circuit, obtain current power detection value,, obtain the power output of described power detection value correspondence according to the power detection value of preserving and the corresponding relation of power output;
The corresponding relation of power detection value and power output is to obtain when producing calibration, and the corresponding relation of power detection value and power output can have two kinds of file layouts, and a kind of is to store each fixedly power detection value of power output correspondence; Usually, be linear between power detection value and the power output, so also can store the coefficient of determining the relation between power output and the power detection value.
At first kind of file layout, when producing calibration, the method for obtaining the corresponding relation of power detection value and power output comprises:
The power amplifier of described terminal sends different power outputs respectively, measures the power detection value of this power output correspondence from testing circuit, and power output and the corresponding power detection value thereof that obtains is kept in the memory.Adopt this storage mode, in order to obtain being worth as far as possible accurately, the power output that need detect gets many as much as possible, and the memory space that takies so also will increase, and, increased the time of calibrating.
At second kind of file layout, when producing calibration, the method for obtaining the corresponding relation of power detection value and power output comprises:
A given benchmark power output D
0With reference output power P
1, the power amplifier of described terminal sends this benchmark power output D respectively
0With reference output power D, from testing circuit, measure the power detection value V of correspondence when sending the benchmark power output
0The power detection value V of correspondence during with transmission reference output power D
1, because be linear between power output and the power detection value, therefore, have following equation to set up:
P
1=D
0+C(V
1-V
0)
According to this equation, can calculate the value of C, then, can obtain its corresponding power output P for any one power detection value V
Out:
P
out=D
0+C(V-V
0)
In memory, preserve parameter D
0, V
0, and C.Adopt this file layout,, all can calculate its corresponding power output for any power detection value, the accuracy rate height, and also the memory space that takies is also seldom, has also reduced the time of calibration simultaneously.
Step 301b: according to the indication of received power adjustment instruction, and the relation between described power output and the default maximum rated power output, last emitted power grade done corresponding adjustment after, as emitted power grade next time.
If described power adjustment instruction is when falling DOWN, then step 301b comprises:
Behind step-length STEP of last emitted power grade downward modulation, as emitted power grade next time.Wherein, step-length STEP gives terminal by network side by transmitting signaling downwards, can be 3dB, 2dB or 1dB.
If described power adjustment commands is that then step 301b comprises when rising UP:
Judge described power output P
OutWhether more than or equal to the maximum rated power output P of this terminal
MaxAmount of offseting downward δ with it
MinPoor, promptly judge (P
Out〉=P
Max-δ
Min), if, with last emitted power grade as emitted power grade next time, otherwise, enter steps A;
Steps A, judgement (P
Out+ STEP) whether greater than (P
Max+ δ
Max), δ wherein
MaxFor the maximum rated power output side-play amount that makes progress, if then continue step B, otherwise enter step C;
Step B, judge whether STEP equals 1dB, if, then last emitted power grade is handed over the emitted power grade as next, otherwise described current step-length is deducted 1dB as current effective power step-length, promptly STEP=STEP-1 returns steps A;
Step C, last emitted power grade raised a current step-length STEP after, as emitted power grade next time.
Step 302: according to the power grade of storage and the corresponding relation of power control signal, obtain the power control signal of described power grade correspondence, and this power control signal is sent to sender.
Wherein, the corresponding relation of power grade and power control signal determines that when producing calibration in specific implementation process, power control signal is the APC control word.
When producing calibration, the method for corresponding relation of obtaining power grade and APC control word comprises shown in Fig. 4 A:
S401A: launch the power of all grades respectively at power amplifier, measure and preserve the APC control word of each power grade correspondence;
S402A: judge the proportionate relationship between each group power grade and APC control word, the APC control word that departs from linear concerns carried out linear fit, shown in Fig. 4 B, and with the data record after the match in the APC calibration chart.
This calibrating mode has solved the nonlinear characteristic between power grade and the APC control word, for bigger input power, also can obtain corresponding APC control word, and can eliminate of the influence of extraneous factors such as temperature, voltage the corresponding relation of power grade and APC control word according to linear fit.
Certainly, if less demanding, can be not the corresponding relation of power grade and APC control word not be carried out linear fit yet.
Description above engaging, as can be known, when producing calibration, the data that deposit in the memory are as shown in table 7.
The APC calibration chart of table 7 embodiment of the invention
Benchmark power output D
0 |
xxxx |
Benchmaring power V
0 |
xxxx |
Detection power coefficient C |
xxxx |
Power grade (dBm) |
The APC control word |
26 |
xxxx |
25 |
xxxx |
24 |
xxxx |
23 |
xxxx |
22 |
xxxx |
21 |
xxxx |
... |
... |
xxxx |
xxxx |
... |
... |
-50 |
xxxx |
Behind definite emitting power grade next time, Base Band Unit reads corresponding APC control word from memory, the APC control word is sent to sender.
Step 303: sender sends the signal of corresponding power size according to described APC control word.
In the embodiment of the invention method flow of measuring terminals transmitting power as shown in Figure 5, this method is applied to comprise the terminal of power amplifier, sender, memory and signal processor.Mainly comprise the steps:
Step 501: when the terminal operate as normal, obtain the current power detection value that described signal processor measures.
Step 502:, determine the power output of described power detection value correspondence, i.e. the transmitting power of current terminal according to the power detection value of preserving in the memory and the corresponding relation of power output.
If what preserve in the memory is the coefficient of determining the relation between power detection value and the power output, then can calculate current transmission power level according to current power detection value.
If what preserve in the memory is the power detection value of concrete power output correspondence, then can therefrom obtains with current power detection and be worth the corresponding power output of immediate power detection value, the i.e. transmission power level of described terminal.
Though above-mentioned is that example describes with the TD-SCDMA terminal, is not limited to this, according to foregoing description, the processing mode of obviously knowing its processing mode and TD-SCDMA system terminal in like manner for other similar systems those skilled in the art.
The embodiment of the invention is a kind of terminal power control method based on closed loop, employing to the insensitive sample circuit of environmental factor and power-sensing circuit to the detection of taking a sample of terminal emitted power, according to the transmitting power of the performance number control terminal that detects, reduced the complexity of circuit again; When producing calibration, when power grade greatly when making power grade and APC control word not satisfy linear relationship, the method for employing linear fit is carried out match, has solved the nonlinear characteristic of power amplifier; Because the embodiment of the invention has been carried out accurate control to the maximum transmission power of terminal, improved the accuracy of maximum transmission power, make the index affluence of maximum transmission power measure, thereby can reduce the required precision of producing calibration and test, thereby enhance productivity; The power control algorithm that provides of the embodiment of the invention is simple in addition, understands easily, in practice operation easily.
Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these changes and modification interior.