KR100640337B1 - Aparatus for pn despreading in the cdma system - Google Patents

Abstract

The despreading apparatus sequentially spreads the N number of PN despread signals generated by despreading the N number of mobile station PN signals sequentially delayed in units of PN chip sections with respect to the base station PN signal at a rate of N multiples of the PN chip sections. Output In addition, since the configuration of performing the detection energy calculation and the comparison operation with the threshold value at the output terminal of the despreading device operates at a rate of N multiples of the PN chip interval unit, the capture device according to the present invention is determined as an efficient hardware configuration. N acquisitions can be performed for the hypothesis during the PN chip period.

Despreader, serial capture device, parallel capture device, PN high speed search device.

Description

Despreading device of mobile communication system using code division multiple access method {APARATUS FOR PN DESPREADING IN THE CDMA SYSTEM}             

1 is a diagram showing an example of a conventional acquisition circuit provided in a mobile station in a CDMA mobile communication system.

2 is a diagram showing an example of a conventional acquisition circuit provided in a mobile station in a CDMA mobile communication system.

3 illustrates a despreading apparatus according to an embodiment of the present invention.

Figure 4 is an operation waveform diagram of the actual implementation of the despreading apparatus according to an embodiment of the present invention.

Fig. 5 is a diagram showing an example of a CDMA acquisition circuit to which the present invention is applied.

The present invention relates to a receiver of a mobile communication system, and more particularly to a capture device of the receiver.

In a mobile communication system using a code division multiple access (hereinafter referred to as CDMA) scheme, an operation of an acquisition circuit provided in a mobile station detects a multipath above a predetermined power level for initial synchronization acquisition and handoff. Can be divided into actions.

When the power is turned on, the mobile station first performs an initial synchronization acquisition operation that acquires synchronization of a pilot channel. That is, the mobile station transmits its PN code to the phase of the one having the largest energy among the plurality of pilot signals received from neighboring base stations, that is, PN-Offset. Motivate After performing the initial synchronous acquisition operation, the mobile station performs symbol demodulating and channel decoding operations on the received signal to restore the original data at the transmitting end.

On the other hand, in the CDMA mobile communication system, the initial synchronization acquisition operation of the mobile station can be classified into two types. In this case, the mobile station first calculates the detection energy according to the correlation between the base station generated pseudo-niose (PN) sequence and the mobile station generated PN sequence received at an arbitrary time point. The mobile station then compares the result with the threshold. At this time, if the calculation result is less than the threshold value, the mobile station shifts the phase of the mobile station generation PN sequence for one PN chip period, and then performs calculation and comparison operation for a new hypothesis. However, if the calculation result is larger than the threshold value, since the mobile station generation PN sequence is within a predetermined limit error, the mobile station further refines the operation of calculating the detection energy and comparing the threshold value to find the correct synchronization. That is, the mobile station performs a tracking operation. In addition, various capturing operations have been proposed, such as adjusting the integration section or the number of hypotheses or adjusting the window chip size. The initial synchronization acquisition operation of the mobile station may be classified into a serial search method and a parallel search method.

1 is a diagram showing an example of a conventional acquisition circuit provided in a mobile station in a CDMA mobile communication system.

The despreader 110 performs an operation of multiplying a base station PN sequence input at an arbitrary time point and a mobile station PN sequence generated from the mobile station PN sequence generator 120 within a predetermined integration period. The despreader 110 outputs the result of the multiplication operation to the correlator 130. The correlator 130 calculates the detection energy according to the correlation between the two PN sequences. The controller 140 compares the detected energy with a threshold. If the detected energy is less than the threshold value, the controller 140 outputs a phase shift control signal to the mobile station PN sequence generator 120 to phase shift the mobile station PN sequence in units of PN chip intervals. As a result, the acquisition circuit performs a comparison operation between the calculation operation of the detection energy and the threshold for the new hypothesis phase shifted during the 1 PN chip period. However, if the detection energy is greater than the threshold value, the controller 140 determines that the capture operation is successful.

However, the acquisition circuit of FIG. 1 has the advantages of simplicity of operation and hardware implementation due to a single despreader configuration. However, as described above, the acquisition circuit of FIG. 2 performs a processing operation on an input base station PN sequence in series, and performs an acquisition time because a single calculation operation and a comparison operation on the hypothesis are performed during the PN chip period. There is a problem that this is slow.

2 is a diagram showing an example of a conventional acquisition circuit provided in a mobile station in a CDMA mobile communication system. A description with reference to FIG. 1 is as follows.

As shown in FIG. 2, the capture circuit of FIG. 2 includes the first series capture circuit 210 to the N-th series capture circuit 2N0. Each of the series acquisition circuits has the same configuration.

The despreader 212 provided in the first serial acquisition circuit 210 stores the mobile station PN sequence generated from the base station PN sequence 211 and the first mobile station PN sequence generator 214 input at an arbitrary time point within the set integral period. Multiply by. The despreader 212 then outputs the result of the multiplication operation to the correlator 216. The correlator 216 calculates the detection energy according to the correlation between the two PN sequences. The controller 218 then compares the detected energy with a threshold. If the detected energy is less than the threshold value, the controller 218 outputs a phase shift control signal to the first mobile station PN sequence generator 214 to phase shift the mobile station PN sequence by PN chip intervals. As a result, the first serial capture circuit 210 performs a comparison operation between the calculation operation of the detection energy and the threshold value again. However, if the detected energy is greater than the threshold, the controller 218 determines the capture operation as successful. The operation of the second series capture circuit 220 to the N-th series capture circuit 2N0 is the same as that of the first series capture circuit 210.

On the other hand, the base station PN sequence 211 to base station PN sequence 22N may be a signal transmitted by a single carrier, and may also be a signal transmitted by a plurality of carriers. Further, the mobile station PN sequences respectively output from the first mobile station PN sequence generator 214 to the Nth mobile station PN sequence generator 2N4 may have different phase differences. That is, the first serial acquisition circuit 210 to the N-th serial acquisition circuit 2N0 may attempt to search from different mobile station PN sequence start points with respect to the base station PN sequence to be inputted, respectively.

In the description of FIG. 2, the parallel acquisition circuit can be configured with a plurality of series acquisition circuits in parallel and can simultaneously process the inputted base station PN sequence. Therefore, the parallel acquisition circuit can perform a plurality of calculation and comparison operations for the hypothesis during the average acquisition time or the single PN chip period as fast as the number of series acquisition circuits provided. However, the parallel acquisition circuit has a complicated operation, and it is difficult to implement hardware, such as an increase in hardware configuration, compared to the serial acquisition circuit.

As described above, since the acquisition circuit of the conventional CDMA receiver uses the acquisition method of one PN chip interval unit, it can be seen that a problem occurs that the acquisition time becomes slow or the burden of hardware increases. have.

Accordingly, an object of the present invention is to despread an N number of PN despread signals generated by despreading an N number of mobile station PN signals sequentially delayed in units of PN chip intervals with respect to a base station PN signal input in a code division multiple access type mobile communication system. To provide a despreading device for sequentially outputting at a rate of N multiples of the PN chip interval unit.

Another object of the present invention is to provide a capturing apparatus for performing a plurality of capturing operations on a hypothesis during a predetermined PN chip period as an efficient hardware configuration in a code division multiple access mobile communication system.

In order to achieve the above object, according to the present invention, a despreading apparatus of a mobile communication system using a code division multiple access scheme sequentially delays N number of signals by sequentially delaying the input P-N signal in units of P-N chip intervals. A P-N signal delayer for outputting a mobile station P-N signal, and a N-number of mobile station P-N signals which are sequentially delayed in units of the P-N chip intervals with respect to the input base station P-N signal, A P-en despreader for outputting a P-en despread signal, a counter operating at a clock of N times the rate of the P-en chip, and a clock of the counter at a rate of N multiples of the P-en chip interval. And a multiplexer for sequentially outputting the N number of P-n despread signals.

In addition, the present invention provides an apparatus for acquiring a mobile communication system using a code division multiple access method, comprising: a mobile station P-en generator for generating a mobile station P-en signal, and a unit of P-en chip interval with respect to the inputted mobile station-en-signal. A P-N signal delayer which sequentially outputs N number of delayed mobile station P-N signals, a counter operating at a clock of N times the rate of the P-N chip, and an input base station P-N signal N multiples of the P-en despread signal generated by despreading the N number of mobile station P-en signals sequentially delayed in units of the P-en chip intervals, N times the unit of the P-en chip intervals through the clock of the counter A despreader that sequentially outputs the rate at a rate of; Characterized by a controller for instructing the phase made of an yen movement of chip interval units - group, and the detected energy is less than the threshold, the P-P of the circle generator.

In addition, the present invention provides an apparatus for acquiring a mobile communication system using a code division multiple access method, comprising: a mobile station P-en generator for generating a mobile station P-en signal, and a unit of pie-en chip interval with respect to an inputted mobile station P-en signal. A P-N signal delayer that sequentially outputs the N number of delayed P-N signals by sequentially delaying the P-N signal, and the N number of P-Ns which are sequentially delayed in units of P-N chip intervals with respect to the input base station P-N signal. A despreader for sequentially outputting the N number of P-n despread signals generated by despreading the signal at a rate of N multiples of the P-en chip interval unit, and outputting the despreading device during a predetermined integration period An accumulator that accumulates, an energy calculator that calculates a detected energy for the output of the accumulator, and a P-en chip section stage of the P-en generator if the detected energy is less than a threshold value. It is characterized in that a plurality of serial capturing device consisting of a controller for commanding the above phase shift is made in parallel.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in the following description of the present invention, if 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.

3 is a diagram illustrating a despreading apparatus according to an exemplary embodiment of the present invention. Hereinafter, a description will be given with reference to FIGS. 1 and 2.

PN generator 310 generates a mobile station PN_I signal and a mobile station PN_Q signal. The PN_I signal delay unit 320 and the PN_Q signal delay unit 330 input the mobile station PN_I signal and the mobile station PN_Q signal, respectively, to delay the corresponding number (N times) in units of PN chip sections, and delay each N number. The mobile station PN_I signal and the mobile station PN_Q signal are output to the despreader 330. The PN_I signal delay 320 may be configured of the first delay elements 321 to the Nth delay elements 32N. In addition, each delay element may be a shift register, and the PN_I signal delay units 320 are output from respective delay elements (N number), and the N number of mobile stations sequentially delayed in units of PN chip intervals. The PN_I signal is output to the despreader 330. Likewise, the PN_Q signal delay unit 330 may be configured of the first delay element 331 to the Nth delay element 33N. Each delay element can also be a shift register. The PN_Q signal delay unit 330 outputs the N number of mobile station PN_Q signals sequentially output from each delay element (N number) and sequentially delayed in units of PN chip sections to the despreader 330.

The despreader 330 multiplies or XORs the input base station PN_I signal and the base station PN_Q signal with each of the N number of mobile station PN_I signals and the mobile station PN_Q signals which are sequentially delayed in units of the PN chip interval, or the base station PN_I signal and the base station PN_I signal. Despread the PN_Q signal. As a result, the despreader 330 outputs the first PN_I despread signal and the first PN_Q despread signal to the Nth PN_I despread signal and the Nth PN_Q despread signal. However, at this time, each despread signal has a rate of the PN chip.

N 레이트의 클럭으로 동작하는 카운터(350)의 제어신호를 입력하여 상기 제1 PN_I 역확산신호 및 제1 PN_Q 역확산신호 내지 제N PN_I 역확산신호 및 제N PN_Q 역확산신호를 순차적으로 출력한다. 그런데 이때, 상기한 각 PN_I 역확산신호 및 PN_Q 역확산신호는 PN 칩

N 레이트가 된다.The multiplexer 340 is a PN chip.

The first PN_I despread signal, the first PN_Q despread signal, the Nth PN_I despread signal, and the Nth PN_Q despread signal are sequentially outputted by inputting a control signal of the counter 350 that operates at a N-rate clock. . In this case, each of the PN_I despread signal and the PN_Q despread signal are PN chips.

N rate.

4 is an operation waveform diagram of an actual implementation and experiment of the despreading apparatus according to the embodiment of the present invention. Hereinafter, a description will be given with reference to FIGS. 1 to 3.

Reference numeral 410 denotes a PN chip operating clock. Reference numeral 420 denotes a base station PN_I signal and a base station PN_Q signal, respectively. The PN_I signal delay unit 320 and the PN_Q signal delay unit 330 input the mobile station PN_I signal and the mobile station PN_Q signal, respectively, and delay the corresponding number (8 times) in units of PN chip intervals, and are denoted by reference numeral 430. The mobile station PN_I signal to the seventh delayed mobile station PN_I signal are output, and the mobile station PN_Q signal to the seventh delayed mobile station PN_Q signal, which are indicated by reference numeral 440, are outputted to the despreader 330.

The despreader 330 XORs each of the eight mobile station PN_I signals 430 and the mobile station PN_Q signals 440 which are sequentially delayed in units of the PN chip intervals to the base station PN_I signal and the base station PN_Q signal 420. A base station PN_I signal and a base station PN_Q signal 420 are despread for PN. As a result, the despreader 330 outputs the first PN_I despread signal to the eighth PN_I despread signal 450. The despreader 330 outputs the first PN_Q despread signal to the eighth PN_Q despread signal 460. At this time, each despread signal has a rate of the PN chip.

N 레이트의 클럭으로 동작하는 카운터 제어신호(470)에 따라, 입력되는 상기 제1 PN_I 역확산신호 내지 제8 PN_I 역확산신호 (450) 와 제1 PN_Q 역확산신호 내지 제8 PN_Q 역확산신호(460)를 순차적으로 출력한다.The multiplexer 340 is a PN chip

The first PN_I despread signal to the eighth PN_I despread signal 450 and the first PN_Q despread signal to the eighth PN_Q despread signal according to the counter control signal 470 operating at a clock of the N rate. 460 is sequentially output.

N 레이트의 클럭으로 상기한 제1 PN_I 역확산신호 및 제1 PN_Q 역확산신호 내지 제N PN_I 역확산신호 및 제N PN_Q 역확산신호(상기 도 4의 PN_I 역확산신호 및 PN_Q 역확산신호 참조)를 출력한다는 것을 알 수가 있다.In the description of FIGS. 3 to 4, the CDMA despreading apparatus according to an embodiment of the present invention uses the signal delay units 320 and 330 to output the mobile station PN_I signal and the mobile station PN_Q signal output from the PN generator 310. The N-delayed mobile station PN_I signals and the mobile station PN_Q signals are respectively outputted by sequentially delaying the PN chip sections. The despreader 330 multiplies or XORs each of the N number of mobile station PN_I signals and the mobile station PN_Q signals sequentially delayed in units of the PN chip interval to the input base station PN_I signal and the base station PN_Q signal, thereby demultiplexing the first PN_I despreader. A signal and a first PN_Q despread signal to an Nth PN_I despread signal and an Nth PN_Q despread signal. However, at this time, each despread signal has a rate (Rate) of the PN chip. The multiplexer 340 is a PN chip

The first PN_I despread signal and the first PN_Q despread signal to the Nth PN_I despread signal and the Nth PN_Q despread signal using the N-rate clock (see the PN_I despread signal and the PN_Q despread signal of FIG. 4). You can see that it outputs

5 is a diagram showing an example of a CDMA acquisition circuit to which the present invention is applied. Hereinafter, a description will be given with reference to FIGS. 1 to 4.

The input controller 510 receives the base station PN_I signal and the base station PN_Q signal, which are converted into the received and baseband, and outputs them to the ON despreader 520 and the LATE despreader 530.

The PN generator 505 generates a mobile station PN_I_ON signal, a mobile station PN_Q_ON signal, a mobile station PN_I_LATE signal, and a mobile station PN_Q_LATE signal having half chip phase differences from each other. The ON despreading device 520 despreads the PNs by the N number of mobile station PN_I_ON signals and the mobile station PN_Q signals which are sequentially delayed in units of PN chip intervals with respect to the base station PN_I signal and the base station PN_Q signal. Generate a number of PN_I_ON despread signals and PN_Q_ON despread signals. In this case, the N number of PN_I_ON despread signals and the PN_Q_ON despread signals have a rate of PN chip intervals. The ON despreader 520 again outputs the N number of PN_I_ON despread signals and the PN_Q_ON despread signals at a rate of N multiples of the PN chip period. Similarly, the LATE despreading apparatus 530 despreads the PNs with N mobile station PN_I_LATE signals and mobile station PN_Q_LATE signals sequentially delayed in units of PN chip intervals with respect to the base station PN_I signal and the base station PN_Q signal. Generate a number of PN_I_LATE despread signals and PN_Q_LATE despread signals. In this case, the N number of PN_I_ON despread signals and the PN_Q_ON despread signals have a rate of PN chip intervals. The LATE despreader 530 again outputs the N number of PN_I_LATE despread signals and the PN_Q_LATE despread signal at a rate of N multiples of the PN chip period. That is, it can be seen that the ON despreader 520 and the LATE despreader 530 respectively output N number of PN despread signals during a predetermined PN chip period. The ON despreader 520 and the LATE despreader 530 may be configured as the despreader of FIG. 3.

The gain controller 542 and the gain controller 544 input the PN_I_ON despread signal and the PN_Q_ON despread signal, respectively, to control the gain of the signal strength. Similarly, the gain controller 546 and the gain controller 548 input the PN_I_LATE despread signal and the PN_Q_LATE despread signal, respectively, to control the gain of the signal strength.

The first accumulator 552 to the first accumulator 558 respectively accumulate the outputs of the gain controller 542 to the gain controller 548 for the corresponding integration period. The ON energy calculator 562 and the LATE energy calculator 564 calculate the detected energy according to the correlation with respect to the cumulative integral values of the accumulators, respectively. The second accumulator 566 and the second accumulator 570 accumulate and store the number of times set for the outputs of the ON energy calculator 562 and the LATE energy calculator 564. The peak peak detector 568 detects the largest energy value among the energy values stored in the second accumulator 566 and the second accumulator 570 and outputs the highest energy value to the controller 580. The controller 580 outputs a signal to the PN generator 505 when the largest correlation energy value for the hypothesis is smaller than a threshold value. As a result, the PN generator 505 performs a phase shift of the mobile station PN_I signal and the mobile station PN_Q signal for one PN chip period such as a PN sequence generation stop light during one PN chip period, and performs a mobile station PN_I signal for a new hypothesis. Outputs the mobile station PN_Q signal.

In the description of FIG. 5, the two despreaders 520 and 530 output N number of PN despread signals during a predetermined PN chip period. In addition, the gain controller 542 to the gain controller 548 and the first accumulator 552 to the first accumulator 558 and the ON energy calculator provided at the output terminals of the two despreaders 520 and 530. 562, the LATE energy calculator 564, the second accumulator 566, the second accumulator 570, and the peak peak detector 568 operate as N multiples of the PN chip section.

That is, the capturing circuit according to the embodiment of the present invention of FIG. 5 may perform capturing operations such as calculation of detection energy of N times and comparison with a threshold value during a predetermined PN chip period. As a result, according to the embodiment of the present invention, N correlators or N correlators, which are provided at the output terminal of each despreader and calculate the detection energy according to the correlation of the PN sequence of the mobile station and the base station, as shown in FIG. And N controllers are unnecessary.

Also, since the acquisition circuit according to the embodiment of the present invention generates N PN despread signals during a predetermined PN chip period, the acquisition circuit of FIG. 1 performs a single acquisition operation for the hypothesis during the predetermined PN chip period. Compared with this, a plurality of capturing operations can be performed on the hypothesis during a predetermined PN chip period, so that the capturing time is improved. Of course, the despreading apparatus according to the embodiment of the present invention outputting N number of PN despread signals during a predetermined PN chip period may be applied to both FIGS. 1 and 2.

As described above, the despreader according to the embodiment of the present invention outputs N number of PN despread signals during a predetermined PN chip period, and an integrator, an energy calculator, a controller, and the like of the output terminal of the despreader are used for the PN chip period. It operates at a rate of N multiples of to calculate N detected energies and compare with a threshold value during a predetermined PN chip period. As a result, it is possible to reduce hardware for performing the operation of calculating the detection energy and comparing the threshold with the threshold value, and also, it is possible to perform a plurality of capturing operations on the hypothesis during a predetermined PN chip period, thereby increasing the capturing time. There is this.

Claims (13)

In the despreading device of a mobile communication system using a code division multiple access method, A P-N signal delayer for sequentially delaying the input P-N signal in units of P-N chip intervals to output N number of delayed P-N signals; A P-DNA despreader that despreads the N-PN signals which are sequentially delayed in units of the P-N chip intervals and outputs N N-P-N signals, , A counter operating at a clock rate of N multiples of the P-en chip; And a multiplexer for sequentially outputting the N number of P-N-despread signals at a rate of N multiples of the P-N chip period through the clock of the counter. The method of claim 1, wherein the P-en signal delay unit, And a N number of delay elements, and outputting the N number of delayed mobile station P-N signals from an output terminal of each delay element. The N-number de-spread signal output from the P-en despreader, And a rate of the P-en chip intervals. In the capture device of a mobile communication system using a code division multiple access method, A mobile station P-en generator for generating a mobile station P-en signal; A P-N signal delayer for sequentially delaying the input P-N signal in units of P-N chip intervals to output N number of delayed P-N signals; A counter operating at a clock rate of N multiples of the P-en chip; The N number of P-N despread signals generated by de-spreading the N number of mobile station P-N signals sequentially delayed in units of P-N chip sections with respect to the inputted base station P-N signal through the clock of the counter A despreading device that sequentially outputs at a rate of N multiples of the unit of the P-en chip; An accumulator for accumulating the output of the despreading device for a set integral period; An energy calculator for calculating the detected energy for the output of the accumulator; And a controller for instructing a phase shift of the P-en chip section of the P-en generator when the detected energy is less than a threshold value. The apparatus of claim 4, wherein the despreader is A P-N signal delay unit configured to sequentially delay the input P-N signal in units of the P-C chip intervals to output the N number of delayed P-N signals; A P-N inverse that despreads the N number of P-N signals sequentially delayed in units of the P-N chip intervals with respect to the inputted base station P-N signal, and outputs the N number of P-N despread signals. Diffuser, And a multiplexer for sequentially outputting the N number of P-en despread signals at a rate of N multiples of the P-en chip interval. The method of claim 5, wherein the P-en signal delay unit, And an N number of delay elements, and outputting the N number of delayed mobile station P-N signals from an output terminal of each delay element. 7. The method of claim 6, wherein the N number of P-en despread signals output from the P-en despreader is: And a rate of the P-en chip intervals. The method of claim 7, wherein the accumulator, energy calculator and controller, And operating at a rate of N multiples of the P-en chip interval to perform N-times calculation of the detected energy and a comparison with a threshold value during a predetermined P-en chip interval. In the capture device of a mobile communication system using a code division multiple access method, A mobile station P-en generator for generating a mobile station P-en signal; A P-N signal delayer for sequentially delaying the input P-N signal in units of P-N chip intervals to output N number of delayed P-N signals; The N number of P-en despread signals generated by despreading the N number of mobile station P-en signals sequentially delayed in units of P-en chip intervals with respect to the inputted base station P-en signal, unit of the P-en chip intervals A despreading device that sequentially outputs at a rate of N multiples of An accumulator for accumulating the output of the despreading device for a set integral period; An energy calculator for calculating the detected energy for the output of the accumulator; And a plurality of serial capturing devices comprising a controller for instructing a phase shift in units of the P-en chip section of the P-en generator when the detected energy is less than a threshold value. 10. The apparatus of claim 9, wherein the despreading apparatus provided in each serial capture device, A P-N signal delay unit configured to sequentially delay the input P-N signal in units of the P-C chip intervals to output the N number of delayed P-N signals; A P-N inverse that despreads the N number of P-N signals sequentially delayed in units of the P-N chip intervals with respect to the inputted base station P-N signal, and outputs the N number of P-N despread signals. Diffuser, A counter operating at a clock rate of N multiples of the P-en chip; And a multiplexer for sequentially outputting the N number of P-en despread signals at a rate of N multiples of the P-N chip interval through the clock of the counter. The method of claim 10, wherein the P-en signal delay unit, And an N number of delay elements, and outputting the N number of delayed mobile station P-N signals from an output terminal of each delay element. 12. The apparatus of claim 11, wherein the N number of P-en despread signals output from the P-en despreader is: And a rate of the P-en chip intervals. 13. The system of claim 12, wherein the accumulator, energy calculator and controller, And operating at a rate of N multiples of the P-en chip interval to perform N-times calculation of the detected energy and a comparison with a threshold value during a predetermined P-en chip interval.

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