CN1177425C - Peak power inhibiting method and device suitable for CDMA communication system - Google Patents

Abstract

The present invention discloses a peak power inhibiting method suitable for a CDMA communication system. In the method, signal amplitude sent to a system power amplifier is predicted in a base band part. If the predicted signal amplitude is larger than a peak-to-average ratio threshold, the base-band signals of each circuit are processed by correspondingly lowering peak-to-average ratio. The present invention discloses a peak power inhibiting device suitable for a CDMA communication system simultaneously, which comprises a digital control oscillator, a predictor, a time delay compensator of the predictor and a preprocessor, wherein the digital control oscillator generates frequency carrying signals. After the base-band signals are modulated by the frequency carrying signals, the base-band signals are sent to the predictor which predicts the signal amplitude. The time delay compensator of the predictor compensates for time delay errors introduced by the predictor. The preprocessor carries out the processing of lowering the peak-to-average ratio to the signals sent out by the time delay compensator of the predictor according to the information of the signal amplitude predicted by the predictor. Due to the adoption of the proposal, the inhibition for the peak-to-average ratio of signals is accurate, the regeneration for the outside band spectrum of the modulated signals can not be caused, and the influence on the signals of an adjacent channel is small.

Description

A kind of method and device that is applicable to the inhibition peak power of cdma communication system

Technical field:

The present invention relates to the inhibition method and the device of the peak power in the cdma communication system.

Background technology:

In cdma communication system, if the signal peak-to-average that is input to the radio-frequency (RF) power amplification end is bigger than the ratio of average power (peak power with), can make that then signal amplitude surpasses the range of linearity of power amplifier, producing Intermodulation Interference and signal band regenerates outward, adjacent channel is caused high interference, and make system transmissions debase, power system capacity reduces.If signal to be sent has higher peak-to-average ratio, for fear of causing out of band signal regeneration, just need power amplifier to have the bigger range of linearity, make power amplifier that bigger rollback be arranged, this can cause power amplification efficiency lower.As seen, peak-to-average ratio is crossed the operational efficiency that senior general influences practical communication system, and reduces the power that peak-to-average ratio can effectively increase power amplifier, improves the efficient of power amplifier, and then reduces to spend in the cost on the power amplifying device.

In the reality, if each single-carrier signal of system is all regarded as phase place cosine signal at random, the inevitable amplitude envelops of multi-carrier signal synthetic after then some single-carrier signal stacks rises and falls non-constant, and occur many higher peak values inevitably, cause the multicarrier signal peak level ratio to be higher than the single-carrier signal peak-to-average ratio.Therefore, the peak-to-average ratio of CDMA multiple carrier communication system signal can be than single carrier cdma communication system signal peak-to-average than higher, and along with the increase of carrier number, the peak-to-average ratio that transmits also can increase.

At present, reduce the cdma communication system signal peak-to-average than following several method is generally arranged: each subcarrier initial phase, the outer artificial signal of superposition band etc. in direct amplitude limit, design spreading code, the change multi-carrier signal.Directly amplitude limit can effectively reduce the signal peak-to-average ratio, but causes in-band noise to disturb easily and the regeneration of modulated signal out of band spectrum, influences adjacent channel, and then can have influence on power system capacity; The redesign spreading code can be subjected to much limiting and bringing a series of problems for the system that agreement limits; Change the initial phase of each sub-carrier signal in the multi-carrier signal, operability is not strong, implements the comparison difficulty; The outer artificial signal of superposition band can reduce cdma communication system signal peak-to-average ratio, but needing to spend than higher cost comes the elimination out of band signal at the rf inputs designing filter in real system.

Summary of the invention

At the problems referred to above, the object of the present invention is to provide a kind of method and device that is applicable to the inhibition peak power of cdma communication system, use said method or device to be with interior frequency spectrum influence smaller so that reduce operating in of peak-to-average ratio to signal, and it is bigger at attenuation outside a channel, less to the neighboring trace effect of signals simultaneously, operation is consuming time less, it is more accurate to suppress signal peak-to-average, and easy operating.

For achieving the above object, the method that is applicable to the inhibition peak power of cdma communication system provided by the invention comprises:

(1) use the standard CF signal baseband signal to be modulated the baseband signal after obtaining modulating;

(2) according to the parameter of the actual downstream link of base station, the Mathematical Modeling of described operating parameter is set up in operations such as paired pulses shaping filter, filtering interpolation and numerical control vibration, and relevant parameter is solidificated in this Mathematical Modeling;

(3) according to the baseband signal after described parameter model and the described modulation, the baseband signal that each carrier wave of system is set through actual pulse shaping, interpolation, modulate, close the peak-to-average ratio behind the road;

(4) according to the baseband signal of each carrier wave of baseband signal prognoses system after described parameter model and the described modulation through actual pulse shaping, interpolation, modulate, close the peak value behind the road;

(5) baseband signal of judging each carrier wave of system according to the baseband signal after described parameter model and the described modulation through actual pulse shaping, interpolation, modulate, close the envelope peak that whether occurs surpassing default peak-to-average ratio thresholding correspondence behind the road, if peak value is done the corresponding operation that reduces peak-to-average ratio to each roadbed band signal.

Above-mentioned is when the signal amplitude that dopes is higher than the peak-to-average ratio thresholding of setting to the corresponding operation that reduces peak-to-average ratio of each roadbed band signal do, and each roadbed band signal of importing is deducted certain numerical value.

Described certain numerical value is for the signal amplitude that dopes deducts described peak-to-average ratio thresholding.

The present invention also provides a kind of device that is applicable to the inhibition peak power of cdma communication system simultaneously, comprising: digital controlled oscillator, fallout predictor, fallout predictor compensation of delay device and preprocessor; Wherein:

Described digital controlled oscillator is used to produce the standard CF signal, so that baseband signal is modulated, obtains base band signal modulated;

Described fallout predictor, be used to receive the process base band signal modulated of described digital controlled oscillator output, parameter according to the real base station down link, the various devices of pulse shaping filter, interpolation filter and digital controlled oscillator for system are set up Mathematical Modeling, and relevant operating parameter is solidificated in this Mathematical Modeling, predicts that the baseband signal of each carrier wave is passed through actual pulse shaping, interpolation, modulated, closes the signal amplitude information that occurs behind the road;

Fallout predictor compensation of delay device is used to produce certain time-delay, with the delay time error of compensation preprocessor introducing;

Preprocessor, be used for the signal amplitude information that goes out according to predictor predicts, the signal that described fallout predictor compensation of delay device is sent reduces the processing of peak-to-average ratio, makes when the signal amplitude that dopes is higher than the peak-to-average ratio thresholding of setting, reduces peak-to-average ratio and operates.

The present invention predicts the signal amplitude of delivering to system power amplifier in baseband portion, if the signal amplitude of prediction is greater than the peak-to-average ratio thresholding, each roadbed band signal is made the corresponding peak-to-average ratio that reduces to be handled, and then make system's peak-to-average ratio controlled, because described processing was carried out before base band pulse is shaped, it is smaller to make that the reduction peak-to-average ratio of the method for the invention operates in the band frequency spectrum influence to signal, attenuation ratio is bigger outside the signal bandwidth scope, and can not cause the regeneration of modulated signal out of band spectrum, thereby the neighboring trace effect of signals is reduced greatly; Simultaneously this method is done consuming time fewly in the time domain drilling, suppresses more accurate, the easy operating of signal peak-to-average, implement to spend cost less.

Description of drawings:

Fig. 1 is four a carrier waves vector composite diagram of delivering to rf inputs;

Fig. 2 is the schematic diagram that the four carrier wave composite vectors of delivering to rf inputs is reduced the peak-to-average ratio operation;

Fig. 3 is the schematic flow sheet of the method for the invention embodiment;

Fig. 4 is 4 carrier wave base station block diagrams of using device of the present invention;

Fig. 5 is a single carrier cdma system block diagram of using device of the present invention;

Fig. 6 is a multi-carrier CDMA system block diagram of using device of the present invention;

Fig. 7 is another multi-carrier CDMA system block diagram of using device of the present invention.

Embodiment:

The present invention is described in further detail below in conjunction with accompanying drawing.

Be that example is introduced the present invention at first with 4 carrier communication systems.With reference to figure 1, through behind the digital controlled oscillator, the vector of four carrier waves is respectively A1, A2, A3, A4, and they form vector M after closing the road, therefore finally need investigate the peak-to-average ratio index at M.Among Fig. 1, the projection final composite vector M of Ai (i=1,2,3,4) on the M direction that is to say that each Ai is right | the contribution of M| value is different.

That is: $\left|M\right|=\underset{i=1}{\overset{4}{\mathrm{\Σ}}}\left|A_i\right|\cos \left(a_i\right)(i=\mathrm{1,2,3,4})$

A in the following formula _iIt is the angle of Ai and M.

Supposing | M| has surpassed thresholding Th, does not transfinite the equidirectional Δ E=|M|-Th that prunes of reply composite vector M in order to guarantee peak-to-average ratio.This is equivalent to reverse vectorial Ai ' of each Ai superposition, with reference to figure 2.Among Fig. 2, | Ai ' | value will be according to each carrier wave vector Ai for closing the contribution degree γ that the road forms M _iDecide.γ _iBe defined as follows:

${\mathrm{\γ}}_i=\frac{\left|A_i\right|\cos \left(a_i\right)}{\underset{i=1}{\overset{4}{\mathrm{\Σ}}}\left|A_i\right|\cos \left(a_i\right)}(i=\mathrm{1,2,3,4})$

So | Ai ' | can calculate with following formula:

$\left|A_i^{\′}\right|=\mathrm{\ΔE}\·{\mathrm{\γ}}_i/\cos \left(a_i\right)=\frac{\mathrm{\ΔE}\·\left|A_i\right|}{\left|M\right|}(i=\mathrm{1,2,3,4})$

So just will close the vector that should reduce on the vector M of road be mapped to each carrier wave through the vector behind the digital controlled oscillator on.If operating in base band, the reduction peak-to-average ratio carries out, then by handle | Ai ' | further be mapped to the operation that just can realize reducing peak-to-average ratio on the base band vector.This operation is all identical for four carrier waves.

Finish aforesaid operations, at first, on time domain, be provided with and reduce peak-to-average ratio thresholding Threshold, and the amplitude peak X that delivers to the rf inputs signal is predicted.If the signal amplitude peak value surpasses thresholding, be X＞Threshold, then write down the feature of peak value, such as parameters such as time of origin, peak height, peak phases, by these parameters signal is handled accordingly, reduced signal peak, make that delivering to radio-frequency (RF) power amplification end signal peak value reduces to below the thresholding Threshold, thereby reduce cdma communication system signal peak-to-average ratio, the line output of going forward side by side.If the rf inputs signal amplitude peak value of prediction is no more than thresholding, promptly X＜Threshold does not then handle.

Make the peak-to-average ratio of cdma communication system signal be lower than threshold value, can adopt method of the present invention.Fig. 3 is the schematic flow sheet of the method for the invention embodiment.Implement the present invention according to Fig. 3, the peak-to-average ratio threshold value to be set in advance, be used to judge whether each roadbed band signal is done the corresponding operation that reduces peak-to-average ratio, like this in the step 1 of the method for the invention, use standard CF signal is modulated baseband signal, the baseband signal after obtaining modulating; In step 2, according to the parameter of the actual downstream link of base station, the Mathematical Modeling of described operating parameter is set up in operations such as paired pulses shaping filter, filtering interpolation and numerical control vibration, and relevant parameter is solidificated in this Mathematical Modeling; In step 3, whether the baseband signal of judging each carrier wave of system according to the baseband signal after described parameter model and the described modulation envelope peak occurs through actual pulse shaping, interpolation, after modulating, close the road, if peak value do not occur, directly carry out step 6 output signal, if peak value, carry out step 4 pair and described envelope peak is carried out the peak value prediction, do the corresponding operation that reduces peak-to-average ratio at step 5 pair each roadbed band signal then according to the baseband signal after the described modulation.That is to say, when the signal amplitude that dopes is higher than the peak-to-average ratio thresholding of setting, each roadbed band signal to input deducts certain numerical value, and this numerical value is the value that the signal amplitude that dopes deducts described peak-to-average ratio thresholding, at last in step 6 output through reducing the signal of peak-to-average ratio.

In above-mentioned steps 3, mainly consider the modeling of paired pulses forming filter.Pulse shaping filter can equivalence be the finite impulse response filter of certain exponent number generally, and the final output result of the finite impulse response filter linearity that can regard the unit impact response of individual data in the list entries as adds and.If peak value has appearred in the envelope that closes behind the road, just need do the corresponding processing that reduces peak-to-average ratio to each roadbed band signal, and then output.

The present invention also provides a kind of device that is applicable to the inhibition peak power of cdma communication system, and this device is called predistorter in concrete the application, reduces system's peak-to-average ratio operation and also can finish by predistorter.The concrete structure of described predistorter embodiment is with reference to the predistorter among the figure 4, it is predicted at the peak value that rf inputs occurs for signal, and carry out preliminary treatment, to reduce the peak-to-average ratio of signal, reach the purpose of control signal peak power, it comprises: digital controlled oscillator 44, fallout predictor 43, fallout predictor compensation of delay device 42 and preprocessor 45; Wherein:

Digital controlled oscillator 44, be used to produce the standard CF signal, baseband signal is modulated, obtain base band signal modulated, make fallout predictor 43 to deliver to the rf inputs signal amplitude by accurately predicting, and the signal amplitude information that dopes is passed to preprocessor 45.

Fallout predictor 43, be used to receive obtaining of described digital controlled oscillator output through base band signal modulated, parameter according to the real base station down link, set up Mathematical Modeling for various devices such as pulse shaping filter, interpolation filter and digital controlled oscillators, and relevant parameter is solidificated in this Mathematical Modeling, according to the described baseband signal of predicting each carrier wave through base band signal modulated through actual pulse shaping, interpolation, modulate, close the envelope peak that occurs behind the road.This process is mainly considered the modeling of paired pulses forming filter.Pulse shaping filter can equivalence be the finite impulse response filter of certain exponent number generally, and the final output result of the finite impulse response filter linearity that can regard the unit impact response of individual data in the list entries as adds and.If peak value has appearred in the envelope that closes behind the road, just each roadbed band signal is done the corresponding processing that reduces peak-to-average ratio, and then output.

Fallout predictor compensation of delay device 42 is used to produce certain time-delay, with the delay time error of compensation preprocessor introducing.It comprises a register, and this register reads in the data of baseband portion, and preserves a period of time in register, produces certain time-delay, with the delay time error of compensation predistorter and preprocessor introducing.

Preprocessor 45, the signal amplitude information that goes out according to predictor predicts, the signal that fallout predictor compensation of delay device is sent reduces the processing of peak-to-average ratio: if the signal amplitude that dopes is higher than the peak-to-average ratio thresholding of setting, then reduce the peak-to-average ratio operation; Otherwise do not handle.

Because preprocessor 45 reduces the operation of peak-to-average ratio and carries out at numeric field, therefore the digital signal that only need send for fallout predictor compensation of delay device in the Mathematical Modeling of being set up is operated, promptly directly deduct certain numerical value for the baseband signal of importing, the size of this numerical value equals the signal amplitude that predictor predicts goes out and deducts set peak-to-average ratio thresholding, make and reach the index request that reduces peak-to-average ratio by the reduction peak-to-average ratio thresholding that the pretreated signal amplitude of result equals to be provided with.

Fig. 4 is 4 carrier wave base station block diagrams of using device of the present invention.Among Fig. 4, on each carrier wave down link of 4 carrier wave base stations, unit 41 produces baseband signal, delivers to the predistorter of back level.Predistorter predicts at the peak value that rf inputs occurs for signal, and carries out preliminary treatment, to reduce the peak-to-average ratio of signal, reaches the purpose of control signal peak power.At first, the baseband signal that baseband signal unit 41 produces is sent in the fallout predictor 43, and digital controlled oscillator 44 produces CF signal, and baseband signal is modulated, deliver to the rf inputs signal amplitude with prediction, and the signal amplitude information that dopes is passed to preprocessor 45.Fallout predictor compensation of delay device 42 produces certain time-delay, with the delay time error of compensation predistorter introducing.The signal amplitude information that preliminary treatment 45 dopes according to fallout predictor 43, the signal that fallout predictor compensation of delay unit 42 is sent reduces the processing of peak-to-average ratio: if the signal amplitude that dopes is higher than the reduction peak-to-average ratio thresholding of setting, then reduce the peak-to-average ratio operation; Otherwise do not handle.Signal through predistorter was handled is sent to pulse shaping filter 46.Pulse shaping filter 46 carries out pulse-shaping for signal, to reduce intersymbol interference.2 tunnel CF signal that produce through 2 road signals of pulse-shaping and digital controlled oscillator 47 in multiplier, multiply each other the back and add and, (handle about coherent signal in the multiplier, see accompanying drawing 5 and explanation thereof for details) carried out intermediate frequency quadrature and modulated.Signal addition in adder 49 that each carrier wave down link produces becomes the multi-transceiver combination signal.Signal is sent to rf inputs then.

Fig. 5 is a single carrier cdma system block diagram of using device of the present invention.Among Fig. 5, on the down link of single carrier, the sequence of complex-valued chips that produces by spread spectrum is divided into real part and imaginary part 2 road signals after by deserializer 51, and this 2 road signal is sent into predistorter 52 respectively and predicted and preliminary treatment.Treated signal is delivered to pulse shaping filter 53 and is carried out pulse-shaping, to reduce intersymbol interference.2 tunnel CF signal that 2 road signals and digital controlled oscillator 54 produce multiply each other in multiplier 55, and sum up in adder 56, carry out the intermediate frequency quadrature modulation.

Fig. 6 is a multi-carrier CDMA system block diagram of using device of the present invention.Among Fig. 6, on each carrier wave down link, the sequence of complex-valued chips that produces by spread spectrum is divided into real part and imaginary part 2 road signals after by deserializer 61, and this 2 road signal is sent into predistorter 62 respectively and predicted, and carries out preliminary treatment.Treated signal is delivered to pulse shaping filter 63 and is carried out pulse-shaping, to reduce intersymbol interference.2 tunnel CF signal that 2 road signals and digital controlled oscillator 64 produce multiply each other in multiplier 65, and sum up in adder 66, carry out the intermediate frequency quadrature modulation.The carrier frequency that it should be noted that each carrier wave down link is mutually different, and promptly in each carrier wave down link, the frequency of the CF signal that digital controlled oscillator 64 produces is different.Signal addition in adder 67 that each carrier wave down link produces is carried out digital signal and is closed the road, becomes the multi-transceiver combination signal.Deliver to radio frequency then.

Fig. 7 is another multi-carrier CDMA system block diagram of using device of the present invention.Among Fig. 7, on each carrier wave down link, the sequence of complex-valued chips that produces by spread spectrum separately becomes real part and imaginary part 2 road signals after by deserializer 71, and this 2 road signal is sent into predistorter 72 respectively and predicted, and carries out preliminary treatment.Treated signal is delivered to pulse shaping filter 73 and is carried out pulse-shaping, to reduce intersymbol interference.2 tunnel CF signal that 2 road signals and digital controlled oscillator 74 produce multiply each other in multiplier 75, and sum up in adder 76, carry out the intermediate frequency quadrature modulation.The carrier frequency that it should be noted that each carrier wave down link is mutually different, and promptly in each carrier wave down link, the frequency of the CF signal that digital controlled oscillator 74 produces is different.The signal that each carrier wave down link produces becomes analog signal by analog to digital converter 77.Analog signal addition in analog adder 78 that each carrier wave down link produces is carried out analog signal and is closed the road, becomes the multi-transceiver combination signal.This multi-transceiver combination signal is sent in the controller 79.Controller 79 is provided with a switching signal K: work as K=1, signal is sent to radio frequency; K=0, signal are sent to envelope detector 710.The initial value of described switching signal K is set to 0.When starting with preheating in the base station, because the initial value of switching signal K is set to 0, signal is not sent to rf inputs, but delivers to envelope detector 710 earlier, carries out envelope detection, and the peak-to-average ratio of signal calculated.The peak-to-average ratio information of signal is sent in the delay process unit 713.For analogue device, such as the later analog line of digital to analog converter 77, analog adder 78 devices such as grade have been introduced the time-delay of different numerical value in each single carrier passage, causing each single carrier to close the road is after the multi-carrier signal, the signal peak-to-average ratio is still than higher phenomenon, delay process unit 73 can carry out certain adjustment to the parameter setting of predistorter 72, such as readjusting each carrier wave fallout predictor compensation of delay unit 42, though make analogue device in each single carrier passage, introduce the time-delay of different numerical value, but it is that peak-to-average ratio still can be lower than set thresholding after the multi-carrier signal that each single carrier closes the road.

Finish when above-mentioned adjustment process starts with preheating in the base station,, can think that in considerable time, this parameter needn't be adjusted again in case the parameter adjustment of predistorter finishes.Therefore the process of this adjustment does not influence the continuous output of base station signal, can not cause the interruption of base station communication.In case the parameter adjustment of predistorter finishes, it is constant that switching signal K=1 keeps, and treated signal will directly be delivered to radio frequency.

Claims (5)

1, a kind of method that is applicable to the inhibition peak power of cdma communication system comprises:

(1) use the standard CF signal baseband signal to be modulated the baseband signal after obtaining modulating;

(2) according to the parameter of the actual downstream link of base station, the Mathematical Modeling of described operating parameter is set up in operations such as paired pulses shaping filter, filtering interpolation and numerical control vibration, and relevant parameter is solidificated in this Mathematical Modeling;

(3) according to the baseband signal after described parameter model and the described modulation, the baseband signal that each carrier wave of system is set through actual pulse shaping, interpolation, modulate, close the peak-to-average ratio behind the road;

(4) according to the baseband signal of each carrier wave of baseband signal prognoses system after described parameter model and the described modulation through actual pulse shaping, interpolation, modulate, close the peak value behind the road;

(5) whether the baseband signal of judging each carrier wave of system according to the baseband signal after described parameter model and the described modulation envelope peak occurs through actual pulse shaping, interpolation, after modulating, close the road, if peak value is done the corresponding operation that reduces peak-to-average ratio to each roadbed band signal.

2, the method for inhibition peak power according to claim 1, it is characterized in that: the described operation of each roadbed band signal being made corresponding reduction peak-to-average ratio, be when the signal amplitude that dopes is higher than the peak-to-average ratio thresholding of setting, each roadbed band signal of importing is deducted certain numerical value.

3, the method for inhibition peak power according to claim 2 is characterized in that: described certain numerical value, and for the signal amplitude that dopes deducts described peak-to-average ratio thresholding.

4, a kind of device that is applicable to the inhibition peak power of cdma communication system comprises: digital controlled oscillator, fallout predictor, fallout predictor compensation of delay device and preprocessor;

Described digital controlled oscillator is used to produce the standard CF signal, and baseband signal is modulated, and obtains base band signal modulated;

Described fallout predictor, be used to receive the process base band signal modulated of described digital controlled oscillator output, parameter according to the real base station down link, the various devices of pulse shaping filter, interpolation filter and digital controlled oscillator for system are set up Mathematical Modeling, and relevant operating parameter is solidificated in this Mathematical Modeling, predicts that the baseband signal of each carrier wave is passed through actual pulse shaping, interpolation, modulated, closes the signal amplitude information that occurs behind the road;

Fallout predictor compensation of delay device is used to produce certain time-delay, with the delay time error of compensation preprocessor introducing;

Preprocessor, be used for the signal amplitude information that goes out according to predictor predicts, the signal that described fallout predictor compensation of delay device is sent reduces the processing of peak-to-average ratio, makes when the signal amplitude that dopes is higher than the peak-to-average ratio thresholding of setting, reduces peak-to-average ratio and operates.

5, the method for inhibition peak power according to claim 4, it is characterized in that: described fallout predictor compensation of delay device also comprises register, described register is used to read in the data of baseband portion, and preserves a period of time in register, to produce certain time-delay.

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