KR100291019B1 - Apparatus and method for pn acquisition in cdma system - Google Patents

Abstract

While calculating the phase of the mobile station PN sequence for the base station PN sequence continuously input in real time within the corresponding search window, each partial detection energy for the hypothesis corresponding to the phase shift is calculated and stored by accumulating according to the hypothesis. Then, the phase shift is performed to the first hypothesis in the corresponding search window, and the next partial detection energy for the hypothesis corresponding to each phase shift is calculated, and the accumulation is stored for each hypothesis. As a result, the time intervals between the partial detection energy calculation operations for the predetermined hypothesis are mutually different, and even if the received signal falls into fading, the PN capture probability does not decrease, thereby reducing the average PN capture time.

Description

Apparatus and method for capturing P-N in mobile communication system of code division multiple access method {APPARATUS AND METHOD FOR PN ACQUISITION IN CDMA SYSTEM}

The present invention relates to a receiver in a code division multiple access mobile communication system, and more particularly, to an initial synchronization acquisition device and method.

In general, spread-spectrum communication is a method of spreading and transmitting an information signal to be transmitted over a much wider frequency bandwidth, and then receiving and despreading the signal back to the original frequency bandwidth. In addition, the spread spectrum may be classified into a direct sequence method, a frequency hopping method, a time hopping method, and a hybrid method. A commercially available code division multiple access (hereinafter referred to as CDMA) mobile communication system uses the direct sequence spread spectrum communication technique. That is, when a base station of a CDMA mobile communication system transmits a spread signal by multiplying an information signal by a PN (Pseudo-Noise) sequence of a high data rate, the mobile station of the system generates a start position of itself and a base station of the base station generated PN sequence. Perform an initial synchronous acquisition operation that matches the start position of the mobile station-generated PN sequence.

On the other hand, in the CDMA mobile communication system, the initial synchronization acquisition operation may be classified into a PN acquisition operation and a PN tracking operation. The PN acquisition operation can be divided into an operation of calculating a detection energy according to a correlation between a base station generated PN sequence and a mobile station generated PN sequence received at an arbitrary time point, and comparing the calculated result with a threshold value. have. At this time, if the calculation result is less than the threshold value, the mobile station shifts the phase of the mobile station generated PN sequence, and then continuously performs the PN acquisition operation for the newly received base station generated PN sequence. However, if the calculation result is larger than the threshold, since the mobile station generated PN sequence and the base station generated PN sequence are within a predetermined limit phase error, the mobile station performs a PN tracking operation to find the correct synchronization. The capturing operation may be classified into a serial search method, a parallel search method, and a hybrid 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.

As shown in FIG. 2, the capture circuit of FIG. 2 includes the first series capturing circuit 110 to the N-th series capturing circuit 1N0. Each of the series acquisition circuits has the same configuration.

The despreader 112 provided in the first serial capture circuit 110 may input the base station PN sequence 111 and the mobile station PN sequence generated from the first mobile station PN generator 114 input at an arbitrary time point within the set integral period. Perform the multiplication operation. The despreader 112 outputs the result of the multiplication operation to the correlator 116. The correlator 116 calculates the detection energy according to the correlation between the two PN sequences. The controller 118 then compares the detected energy with a threshold. If the detected energy is less than the threshold value, the controller 118 outputs a phase shift control signal to the first mobile station PN generator 114 to phase shift the mobile station PN sequence by PN chip intervals. As a result, the first serial capture circuit 110 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 118 determines that the capture operation is successful. The operation of the second series acquisition circuit 120 to the Nth series acquisition circuit 1N0 is the same as the operation of the first series acquisition circuit 110 described above.

On the other hand, the base station PN sequence 111 to base station PN sequence 1N1 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 generator 114 to the Nth mobile station PN generator 1N4 may have different phase differences. That is, the first serial acquisition circuit 110 to the N-th serial acquisition circuit 1N0 may attempt to search from different mobile station PN sequence start points for the base station PN sequences to be inputted, respectively.

In the description of FIG. 1, the parallel acquisition circuit can be configured in parallel with a plurality of series acquisition circuits and can simultaneously process an input base station PN sequence. Therefore, the parallel acquisition circuit can perform a plurality of calculation operations and comparison operations on the hypothesis during the average acquisition time or the single PN chip period as fast as the number of serial acquisition circuits provided. However, the parallel acquisition circuit has a problem in that the operation is complicated and hardware implementation is not easy, such as an increase in hardware configuration, compared to the serial acquisition circuit.

2 is a diagram illustrating an example of a conventional PN acquisition circuit in a code division multiple access mobile communication system.

The first multiplier 215 and the second multiplier 220 input a received signal at an arbitrary time point from the antenna 210. In this case, the received signal may be a pilot signal transmitted from the base station in the serving cell, an interference signal transmitted from the serving cell and neighboring cells, and thermal noise generated by the mobile station itself. The pilot signal includes a base station generated PN signal of a serving base station. The first multiplier 215 and the second multiplier 220 are local carriers output from a carrier demodulator (not shown), respectively. Wow Multiplying by the received signal. Thus, the received signal is carrier demodulated and converted into baseband I (In Phase) signal and Q (Quadrature) signal, respectively. The first matched filter 225 and the second matched filter 230 perform a frequency filtering operation on the I and Q signals, respectively, to restore the signal waveform. The I and Q signals output from the first matched filter 225 and the second matched filter 230 are converted into a base station PN-I and a base station PN-Q signal by an A / D converter (not shown). The despreader 235 inputs a mobile station PN-I signal and a mobile station PN-Q signal corresponding to a predetermined hypothesis or first hypothesis from a PN generator (not shown), and the base station input at the arbitrary time point. PN despreading the PN-I signal and the base station PN-Q signal.

The first accumulator 240 and the second accumulator 245 are each a base station PN-I signal and a base station PN despread by the mobile station PN-I signal and the mobile station PN-Q signal corresponding to the first hypothesis, respectively. -Q signal is accumulated during the integration period (N chip period). The first squarer 240 and the second squarer 255 square the outputs of the first accumulator 240 and the second accumulator 245 to detect corresponding portions according to correlations during the integration period. Obtain the energy or first part detection energy. The adder 260 performs an operation of adding the outputs of the first squarer 240 and the second squarer 255.

On the other hand, the partial detection energy calculation operation for the hypothesis of the conventional PN capture circuit is repeated continuously on the time axis by the set number of times (L times). That is, the conventional PN acquisition circuit despreads and accumulates PN base station PN signals continuously received on the time axis with respect to the hypothesis, and obtains the first to Lth detection energy. That is, the third accumulator 265 accumulates the first to L th detection energy continuously input on the time axis with respect to the corresponding hypothesis or the first hypothesis. In this case, as described above, the third accumulator 265 accumulates and stores consecutive partial detection energies for each hypothesis and is implemented as an adder and a single shift register.

The peak detector 270 detects the largest energy value accumulated in the third accumulator 265 and outputs it to the controller 275.

The controller 275 then checks whether the detected energy for the corresponding hypothesis or first hypothesis is greater than the threshold. If the detection energy is less than the threshold value, the controller 275 outputs a phase shift control signal to the PN generator. The PN generator performs a phase shift operation of the mobile station PN signal such as the mobile station PN signal generation stop signal, and outputs a mobile station PN-I signal and a mobile station PN-Q signal corresponding to the next or second hypothesis. As a result, the conventional PN acquisition circuit performs PN despreading and accumulation of base station PN signals continuously received on the time axis for the next hypothesis or the second hypothesis, and performs partial detection energy calculation and comparison operation.

In the above description of FIG. 2, the conventional PN acquisition circuit despreads and accumulates PN base station PN signals continuously received on the time axis with respect to the hypothesis, and obtains the first partial detection energy to the Lth partial detection energy. The conventional PN capture circuit accumulates the first to Lth detection energy and detects the largest energy value. The conventional PN capture circuit performs a comparison operation between the highest energy value and the threshold value for the hypothesis. The operations on the hypothesis of the PN acquisition circuit are then repeated by the chip size of the search window.

3 is a view showing the operation of the conventional PN capture circuit on the time axis. A description with reference to FIG. 2 is as follows.

In FIG. 3, for convenience of explanation, it is assumed that the partial detection energy calculation count for each hypothesis is four times (L = 1 to 4), and the number of hypotheses for each search window is four (W = 1 to 4). In other words, it is assumed that the chip size of the search window is 4 chips. And shown Is the jth partial detection energy of the ith hypothesis, Denotes the detected energy of the Wth hypothesis.

Reference numeral 320 denotes a time axis of real time. That is, the base station PN sequence 300 is continuously input in real time. The start position of the base station PN sequence 300 is referred to as the time point NA 330, and it is assumed that the starting point of the mobile station PN sequence 305 is the time point NB 340. At this time, the base station PN sequence 300 and the mobile station PN sequence 305 is out of phase of the X chip interval 310.

The conventional PN acquisition circuit PN despreads and accumulates the base station PN sequences continuously received on the time axis with respect to the first hypothesis by the mobile station PN sequence output of the PN generator at time point NB 340, and accumulates the N chip intervals 315. First part detection energy of To fourth portion of detection energy Obtain That is, the conventional PN capture circuit continuously performs the calculation operation of the partial detection energies for the first hypothesis on the time axis.

At this time, the third accumulator 265 is the first partial detection energy for the obtained first hypothesis Fourth Partial Detection Energy for the First Hypothesis The peak value detector 170 accumulates the highest energy value, that is, the detection energy of the first hypothesis. Is detected. And controller 275 is And compare with threshold. If above If it is smaller than this threshold, the controller 275 outputs a phase shift control signal to the PN generator. The PN generator then performs a phase shift operation for the mobile station PN sequence. In FIG. 3, the PN generator stops the signal generation operation for one PN chip period, and performs a PN chip positive slew 250 with a mobile station PN sequence. Of course, in some cases, the PN generator may operate at twice the PN chip rate during the PN chip period in which the operation clock is operated, thereby performing PN chip negative slew with the mobile station PN sequence.

By the phase shift operation of the mobile station PN sequence of the PN generator, the conventional PN capture circuit detects the detected energy for the second hypothesis. Perform an operation to obtain. The operation of the second hypothesis of the PN acquisition circuit is the same as that of the first hypothesis described above. In the manner as described above, the conventional PN capturing circuit detects energy for each hypothesis by the number of hypotheses W = 1 to 4 set in the search window or the first search window k = 1. To ) And compare with the threshold value. If the detection energy for each hypothesis is less than the threshold value, the conventional PN capture circuit may detect the detection energy and the threshold value for each hypothesis within the next search window or the second search window (k = 2). Perform the comparison operation of.

In the description of FIG. 3, it can be seen that the conventional PN capture circuit performs the calculation operation of the partial detection energies for each hypothesis continuously on the time axis.

4 is a graph showing an operation process of a conventional PN capture circuit on the time axis. Hereinafter, a description will be given with reference to FIGS. 2 to 3.

As shown, the horizontal axis of the graph means the flow in real time, the vertical axis of the graph means the strength of the received signal. In FIG. 4, for convenience of explanation, it is assumed that the partial detection energy calculation count for each hypothesis is four times (L = 1 to 4), and the number of hypotheses for each search window is four (W = 1 to 4) That is, assume that the chip size of the search window is 4 chips. And shown Denotes the detected energy of the j-th portion of the i-th hypothesis. In addition, it is assumed that the chip section of the X chip section 310 of FIG. 3 is a single chip section.

As shown, TD1 430 means the calculation operation time of the partial detection energies for the first hypothesis, and TD2 440 means the calculation operation time of the partial detection energies for the second hypothesis. Also, TD3 450 denotes a calculation operation time of partial detection energies for the third hypothesis, and TD4 460 denotes a calculation operation time of partial detection energies for the fourth hypothesis.

As described above with reference to FIG. 3, the conventional PN acquisition circuit is a base station PN continuously received on the time axis with respect to the first hypothesis by the mobile station PN sequence output of the PN generator at time point NB 340 during TD1 430. FIG. Despreading and accumulating a sequence of PNs, and detecting the first portion of the first hypothesis for the first hypothesis in units of N chip intervals Fourth Partial Detection Energy for the First Hypothesis Obtain That is, the conventional PN capture circuit continuously performs the calculation operation of the partial detection energies for the first hypothesis on the time axis.

At this time, the third accumulator 265 is the first partial detection energy for the obtained first hypothesis Fourth Partial Detection Energy for the First Hypothesis The peak value detector 270 is the accumulated maximum energy value, that is, the detection energy of the first hypothesis Is detected. And controller 275 is And compare with threshold. If above If it is smaller than this threshold, the controller 275 outputs a phase shift control signal to the PN generator. And PS 350 means one PN chip positive slew of the mobile station PN sequence.

Similarly, the conventional PN acquisition circuit applies the phase shift of the mobile station PN sequence, that is, the second hypothesis, the third hypothesis, and the fourth hypothesis according to the PS 410, the PS 420, and the PS 370. The partial detection energies and the comparison operation with the threshold value are performed.

On the other hand, due to the characteristics of the mobile communication channel, the received signal may experience fading. In addition, when the received signal falls into deep fading, the power of the received signal is lowered by several tens of decibels (dB). Therefore, when the PN acquisition circuit performs the PN acquisition operation, if the received signal falls into fading as described above, the probability of success of the PN acquisition operation of the PN acquisition circuit becomes low. 2 to 4, the calculation operation of the partial detection energies for each hypothesis of the conventional PN capture circuit is continuous on the time axis. As a result, when the received signal falls into fading during the duration of the partial detection energy calculation operation for a hypothesis that the PN sequence synchronization coincides, the conventional PN acquisition circuit calculates the partial detection energies for each hypothesis continuously on the time axis. As a result, the probability of successful PN capturing operation decreases. The received signal strength 470 curve of FIG. 4 shows an example in which the received signal falls into fading during the calculation operation period of partial detection energies for the hypothesis that the actual PN sequence synchronization is consistent. Since it is assumed in FIG. 4 that the chip section of the X chip section 310 is a single chip section, the phase shift of the mobile station PN sequence, that is, the start position of the base station PN sequence 300 and the mobile station are actually performed by the PS 350. The starting position of the PN sequence 305 coincides. However, as shown in FIG. 4, the intensity curve of the received signal falls into fading during the calculation operation period for partial detection energies for the hypothesis that the actual PN sequence synchronization matches, and thus the detection energy for the second hypothesis. Is less than the threshold. That is, the PN capture circuit has a disadvantage in that the PN capture operation success probability decreases, thereby increasing the average capture time.

Accordingly, an object of the present invention is to provide a P-en capturing apparatus and method capable of obtaining time diversity by time difference in calculating operation of respective partial detection energies for a corresponding hypothesis in a code division multiple access type mobile communication system. .

Another object of the present invention is to detect each part of the hypothesis corresponding to each phase shift while moving the phase of the mobile station P-N sequence with respect to the base station P-N sequence in a code division multiple access method mobile communication system within a corresponding search window. Accumulate and store energy for each hypothesis, and accumulate and store each partial detection energy for the hypothesis corresponding to each phase shift, and phase shift to the first hypothesis in the search window, and then re-add to the hypothesis corresponding to each phase shift. The present invention provides an apparatus and a method for calculating a plurality of detection energy for each part of a next time and accumulating and storing the accumulated energy for each hypothesis.

In order to achieve the above objects, the present invention provides a capturing apparatus for a mobile communication system using a code division multiple access scheme, comprising: a mobile station P-N generator for generating a mobile station P-N sequence corresponding to a predetermined hypothesis; A despreader for despreading a P-N sequence into the mobile station P-N sequence, an accumulator for accumulating the output of the de-spreader for a corresponding integration period, and squaring the output of the accumulator to the predetermined hypothesis. A squarer for calculating each partial detection energies, a cumulative storage for accumulating and storing each partial detection energy for each hypothesis in the corresponding search window, and the largest energy among the detected energies of each hypothesis calculated and accumulated as many times as the hypothesis is stored. The P-enfo such as a peak detector for detecting a value and a comparison operation between the largest energy value and a threshold value Controls the overall operation of the apparatus, the blood-characterized by made of an a controller for outputting a phase shift control signal to the generator yen.

In addition, the present invention provides a method for acquiring a PN in a mobile communication system using a code division multiple access scheme, while shifting a phase of a mobile station PN sequence with respect to an inputted base station PN sequence by the number of hypotheses in the corresponding search window. A first process of calculating and storing each partial detection energy for each hypothesis corresponding to each phase shift and accumulating and storing the hypothesis for each hypothesis; and phase shifting the mobile station P-N sequence to the first hypothesis in the corresponding search window. A second process of performing the process again; a third process of performing a comparison between the largest energy value and a threshold value among the detected energies of each hypothesis that have been calculated and accumulated by the number of times set by each hypothesis; If the value is less than the threshold value, the mobile station P-N sequence is phase shifted in the phase shift direction to perform the first process for the next search window. For not performing a third process, again it characterized by a fourth constituted by any process.

1 is a view showing an example of a conventional acquisition circuit provided in a mobile station in a code division multiple access mobile communication system.

2 is a diagram illustrating an example of a conventional PN acquisition circuit in a code division multiple access mobile communication system;

3 is a view showing an operation process of a conventional PN capturing circuit on a time axis;

4 is a graph showing an operation process of a conventional PN capture circuit on a time axis;

5 illustrates a PN capture circuit in accordance with an embodiment of the present invention.

6 is a view showing an operation process of a PN acquisition circuit according to an embodiment of the present invention on a time axis;

7 is a graph showing an operation process of a PN acquisition circuit according to an embodiment of the present invention on a time axis;

8 is a flowchart illustrating a PN capture method according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific details appear in the following description, which is provided to aid a more general understanding of the present invention, and it should be understood by those skilled in the art that the present invention may be practiced without these specific details. It will be self explanatory. 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.

The PN capture circuit according to the present invention does not perform the calculation operation of the partial correlation energies for the hypothesis continuously on the time axis, but gives time difference to the calculation operation of each partial detection energy for the hypothesis. ) Get the effect.

The PN acquisition circuit according to the embodiment of the present invention shifts the phase of the mobile station PN sequence with respect to the base station PN sequence which is continuously input in real time, in order to time the calculation operation of each partial detection energy for the corresponding hypothesis described above. Computation of each partial detection energy for the hypothesis (eg, W = 1 to 4) corresponding to each phase shift is accumulated and stored for each hypothesis. The PN capture circuit shifts the phase to the first hypothesis in the corresponding search window, calculates the next partial detection energy for the hypothesis (W = 1 to 4) corresponding to each phase shift, and accumulates each hypothesis. Perform the save operation. At this time, the phase shift to the first hypothesis in the corresponding search window may be implemented by phase shifting the mobile station PN sequence during the corresponding period in the opposite direction to each phase shift described above. The number of operations described above may be as many as the number of hypotheses in the search window. The number of partial detection energy calculations for each hypothesis can be preset and variable.

5 shows a PN capture circuit according to an embodiment of the invention. Hereinafter, a description will be given with reference to FIGS. 2 to 4.

In FIG. 5, for convenience of explanation, it is assumed that the partial detection energy calculation count for each hypothesis is four times (L = 1 to 4), and the number of hypotheses for each search window is four (W = 1 to 4). In other words, it is assumed that the chip size of the search window is 4 chips. And and shown Is the jth partial detection energy of the ith hypothesis, Denotes the detection energy of the W th hypothesis accumulated and stored for each hypothesis in the accumulator 520.

The first despreader 510 and the second despreader 515 respectively input a mobile station PN-I signal and a mobile station PN-Q signal corresponding to the first hypothesis from the PN generator 505 and are input at an arbitrary time point. PN despreading of the base station PN-I signal and the base station PN-Q signal.

The first accumulator 240 and the second accumulator 245 are each a base station PN-I signal and a base station PN despread by the mobile station PN-I signal and the mobile station PN-Q signal corresponding to the first hypothesis, respectively. -Q signal is accumulated during the integration period (N chip period). The first squarer 250 and the second squarer 255 square the outputs of the first accumulator 240 and the second accumulator 245 to obtain a first square according to the correlation during the integration period. First Partial Detection Energy for Hypothesis Obtain And the first adder 260 is the first partial detection energy for the first hypothesis Is output to the accumulator 520.

The PN acquisition circuit according to the embodiment of the present invention first applies to the base station PN sequence inputted in succession in real time in order to give a time difference to the calculation operation of each partial detection energy for the corresponding hypothesis. Partial detection energy Obtain and store for each first hypothesis. And the PN acquisition circuit performs the phase shift operation of the mobile station PN sequence and detects the first partial detection energy for the second hypothesis. Obtain and store by the second hypothesis. The PN capture circuit again performs a phase shift operation of the mobile station PN sequence and detects the first partial detection energy for the third hypothesis. Obtain and store for each third hypothesis. The PN acquisition circuit again performs a phase shift operation of the mobile station PN sequence and detects the first partial detection energy for the fourth hypothesis. Obtain and store by the fourth hypothesis.

However, at this time, the PN capture circuit according to the embodiment of the present invention again detects the second partial detection energy for the first hypothesis. In order to obtain, the phase of the mobile station PN sequence with respect to the base station PN sequence is shifted in the opposite direction to the phase shifted direction (the number of hypotheses (W = 4) -1) in the corresponding search window.

In addition, the PN acquisition circuit according to the embodiment of the present invention provides the second partial detection energy for the first hypothesis with respect to the base station PN sequence which is continuously input in real time. Obtain and store cumulatively by the first hypothesis. And the PN acquisition circuit performs the phase shift operation of the mobile station PN sequence and detects the second partial detection energy for the second hypothesis. Obtain and store cumulatively for each second hypothesis. The PN capture circuit again performs a phase shift operation of the mobile station PN sequence and detects the second partial detection energy for the third hypothesis. Obtain and store cumulatively for each third hypothesis. The PN acquisition circuit again performs a phase shift operation of the mobile station PN sequence and detects the second partial detection energy for the fourth hypothesis. Obtain and store cumulatively by the fourth hypothesis.

Similarly, the PN acquisition circuit may shift the phase of the mobile station PN sequence with respect to the base station PN sequence which is continuously input in real time, and the third portion for the hypotheses corresponding to each phase shift (eg, W = 1 to 4). Detection energy ( , , , ) And accumulate and store each hypothesis. Similarly, the PN acquisition circuit shifts the phase of the mobile station PN sequence with respect to the base station PN sequence which is continuously input in real time, and detects the fourth partial detection energy for the hypotheses corresponding to each phase shift. , , , ) And accumulate and store it according to the fourth hypothesis.

That is, the accumulator 520 according to the embodiment of the present invention may generate partial detection energies (eg, generated by the phase shift of the mobile station PN sequence). , , , ) Is accumulated by hypothesis and stored. The accumulator 520 may be implemented as a shift register connected in series with the adder and the number of hypotheses. In addition, the accumulator 520 may be implemented as a memory in which regions are divided according to each hypothesis in order to ensure flexibility.

The peak detector 530 may accumulate and store partial detection energies accumulated for each hypothesis in the third accumulator 265. ) Detects the largest energy value. And the controller 540 controls the overall operation of the PN capture circuit of FIG. In particular, the controller 540 performs a comparison operation between the output of the peak detector 530 and the threshold value. If the output is smaller than the threshold value, the phase shift control signal is output to the PN generator 505 to attempt a PN capture operation for the next search window.

6 is a view showing the operation of the PN acquisition circuit according to an embodiment of the present invention on the time axis. Hereinafter, a description will be given with reference to FIGS. 2 to 5.

In FIG. 6, for convenience of explanation, it is assumed that the partial detection energy count for each hypothesis is four times (L = 1 to 4), and the number of hypotheses for each search window is four (W = 1 to 4). In other words, it is assumed that the chip size of the search window is 4 chips. And and shown Is the jth partial detection energy of the ith hypothesis, Denotes the detection energy of the W th hypothesis accumulated and stored for each hypothesis in the accumulator 520.

Reference numeral 320 denotes a time axis in real time. That is, the base station PN sequence 300 is continuously input in real time. The start position of the base station PN sequence 300 is referred to as the time point NA 330, and it is assumed that the starting point of the mobile station PN sequence 600 is the time point NB 340. At this time, the base station PN sequence 300 and the mobile station PN sequence 600 is out of phase of the X chip interval 310.

The PN acquisition circuit according to the embodiment of the present invention uses the PN at the time point NB 340 with respect to the base station PN sequence 300 which is continuously input in real time to give a time difference to the calculation operation of each partial detection energy for the hypothesis. The first portion of the first hypothesis detected energy from the generator 505 to the N chip interval 310 by the mobile station PN sequence output. Obtained and stored in the cumulative storage 520 for each first hypothesis. The PN acquisition circuit then performs one PN chip positive slew 610 of the mobile station PN sequence 600, and detects the first partial detection energy for the second hypothesis. Obtain and store in the cumulative storage 520 for each second hypothesis. The PN acquisition circuit again performs one PN chip positive slew 615 of the mobile station PN sequence 600 and detects the first partial detection energy for the third hypothesis. Obtain and store for each third hypothesis of the cumulative storage 520. The PN capture circuit again performs a PN chip positive slew 620 of the mobile station PN sequence 600 and detects the first partial detection energy for the fourth hypothesis. Obtain and store for each of the fourth hypothesis of the cumulative storage 520.

However, at this time, the PN capture circuit according to the embodiment of the present invention again detects the second partial detection energy for the first hypothesis. In order to obtain, the phase of the mobile station PN sequence with respect to the base station PN sequence is shifted in the opposite direction to the phase shifted direction (the number of hypotheses (W = 4) -1) in the corresponding search window. That is, the time point NS 625 means a negative slew operation period of the PN generator 505 under the control of the controller 540. As shown, PN generator 505 operates at twice the PN chip rate during time point NS 625 to generate mobile station PN sequence 600.

In addition, the PN acquisition circuit according to the embodiment of the present invention detects the second partial energy of the first hypothesis with respect to the base station PN sequence which is continuously input in real time. Obtain and store cumulatively by the first hypothesis. And the PN acquisition circuit performs the phase shift operation of the mobile station PN sequence and detects the second partial detection energy for the second hypothesis. Obtain and store cumulatively for each second hypothesis. The PN capture circuit again performs a phase shift operation of the mobile station PN sequence and detects the second partial detection energy for the third hypothesis. Obtain and store cumulatively for each third hypothesis. The PN acquisition circuit again performs a phase shift operation of the mobile station PN sequence and detects the second partial detection energy for the fourth hypothesis. Obtain and store cumulatively by the fourth hypothesis.

In this manner, the PN acquisition circuit according to the embodiment of the present invention corresponds to each phase shift while shifting the phase of the mobile station PN sequence 600 with respect to the base station PN sequence 300 which is continuously input in real time. Third Partial Detection Energy for Hypotheses (e.g., W = 1-4) , , , ) And accumulates and stores the cumulative storage for each third hypothesis in the accumulator 520. Similarly, the PN capturing circuit shifts the phase of the mobile station PN sequence 600 with respect to the base station PN sequence 300 which is continuously input in real time, and generates hypotheses W = 1 to 4 corresponding to each phase shift. Fourth part detection energy ( , , , ) And accumulates and stores the fourth hypothesis of the cumulative storage 520.

That is, the accumulator 520 according to an embodiment of the present invention may generate partial detection energies (eg, generated by the phase shift of the mobile station PN sequence 600). , , , ) Is accumulated by hypothesis and stored.

7 is a graph showing an operation process of a PN acquisition circuit according to an embodiment of the present invention on a time axis. Hereinafter, a description will be given with reference to FIGS. 2 to 6.

As shown, the horizontal axis of the graph means the flow in real time, the vertical axis of the graph means the strength of the received signal. In FIG. 7, for convenience of explanation, it is assumed that the partial detection energy calculation count for each hypothesis is four times (L = 1 to 4), and the number of hypotheses for each search window is four (W = 1 to 4) That is, assume that the chip size of the search window is 4 chips. And shown Denotes the detected energy of the j-th portion of the i-th hypothesis. In FIG. 3, it is assumed that the chip section of the X chip section 310 is a single chip section.

And, as shown, TD5 (710) means the calculation operation time period for the first partial detection energy of the second hypothesis, TD6 (720) is the calculation operation time period for the second partial detection energy of the second hypothesis TD7 730 means a calculation operation time period for the third partial detection energy of the second hypothesis, and TD8 740 indicates a calculation operation time period for the fourth partial detection energy of the second hypothesis. It means liver.

That is, as described above, the PN capturing circuit according to the present invention does not continuously perform calculation operations on the partial detection energies for the second hypothesis whose synchronization is actually synchronized, without successively performing calculation operations on the partial hypothesis detection energies for the second hypothesis. By giving time difference to the calculation operation, the effect of time diversity is obtained.

The PN acquisition circuit according to the embodiment of the present invention is a method for the mobile station PN sequence 600 to the base station PN sequence 300 which is continuously input in real time in order to time the calculation operation of each partial detection energy for the hypothesis. As the phase shifts, each partial detection energy for the hypothesis corresponding to each phase shift (for example, W = 1 to 4) is calculated and accumulated and stored for each hypothesis. The PN capturing circuit shifts the mobile station PN sequence in the opposite direction to each phase shift during the corresponding period, i.e. (the number of hypotheses (W = 4) -1 in the corresponding search window), and again, each phase described above. It calculates the next detected energy of each part of the hypothesis (W = 1 ~ 4) corresponding to the movement and accumulates and stores the hypothesis by hypothesis.

As a result, it can be seen that the partial detection energy calculation operation time period for the second hypothesis whose synchronization is actually synchronized is time difference across the TD5 710, the TD6 720, the TD7 730, and the TD8 740. have. In addition, the PN capture circuit according to an embodiment of the present invention accumulates and stores the first partial correlation energy of the second hypothesis to the fourth partial correlation energy of the second hypothesis for each second hypothesis, and compares it with a threshold of the maximum peak value. Perform the action. Therefore, in the PN acquisition circuit according to the embodiment of the present invention, even if the received signal falls into fading, the PN acquisition probability does not decrease because the time interval between partial correlation energy calculation operations for each hypothesis is different from each other. You can see that

In FIG. 7, the received signal strength curve 470 shows an example in which the received signal falls into fading. In FIG. 3, it is assumed that the X chip section 310 is a single chip section. However, in the exemplary embodiment of the present invention, the test time intervals for the second hypothesis in which the PN sequence synchronization due to the phase shifting PS 610, NS 625, etc. of the mobile station PN sequence are matched are TD5 710, TD6 720, and TD7. There will be a time difference across 730 and TD8 740. As a result, even if the received signal temporarily fades, the remaining PN acquisition probability during the TD6 720 time period can be compensated by the remaining TD5 710, TD7 730, and TD8 740.

8 is a flowchart illustrating a PN capturing method according to an embodiment of the present invention. Hereinafter, a description will be given with reference to FIGS. 2 to 7.

In operation 805, the controller 540 initializes k (a search window number). In step 810, the controller 540 initializes i (the number of each hypothesis in the search window). The controller 540 initializes j (the number of partial detection energy calculations for each hypothesis). The controller 540 initializes Z (i) (memory region for each hypothesis) of the accumulator 520.

In step 815, the controller 540 shifts the phase of the mobile station PN sequence 600 with respect to the base station PN sequence 300 which is continuously input in real time, and applies the hypothesis (i = 1 to W) corresponding to the phase shift. For partial detection energy Calculate the jth partial detection energy for the ith hypothesis. In operation 820, the controller 540 accumulates and stores the partial detection energy for each hypothesis in the accumulator 520.

In operation 825, the controller 540 checks whether the current i is the last hypothesis in the corresponding search window. If the current i is not the last hypothesis in the search window, in step 830 the controller 540 controls the PN generator 505 to phase shift the mobile station PN sequence 600 in the corresponding direction. The controller 540 again performs the control operations of steps 815 and 820. If the current i is the last hypothesis in the search window, the controller 540 checks whether the partial detection energy is calculated by the number of times (L times) set for each hypothesis in the search window. If the partial detection energy is not calculated by the number of times (L times) set for each hypothesis in the corresponding search window, in step 840, the controller 540 controls the PN generator 505 to determine the phase shift in step 830. In the opposite direction, the mobile station PN sequence 600 is phase shifted during the interval, moving to the first hypothesis in the search window. In this case, the phase shift may be as much as (the number of hypotheses (number of W) -1) in the corresponding search window. The controller 540 again performs the control operations of steps 815, 820, and 825.

When the partial detection energy is calculated by the number of times (L times) set for each hypothesis in the corresponding search window, in step 845, the controller 540 controls the peak detector 530 to accumulate each hypothesis in the accumulator 520. Stored detection energy ( ) Detects the largest energy value. In operation 850, the controller 540 performs a comparison operation between the largest energy value and a threshold value. If the largest energy value is less than the threshold, controller 540 controls PN generator 505 to phase shift mobile station PN sequence 600 in the corresponding direction. The controller 540 performs the above-described control operation of steps 810 to 850 with respect to the next search window k ++.

In the description of FIG. 5 to FIG. 8, the PN capturing apparatus and method according to the present invention do not continuously perform calculation operations on partial correlation energies for a hypothesis on the time axis. With time difference, the effect of time diversity is obtained.

That is, the PN capturing apparatus and method according to an embodiment of the present invention provides a method for determining a mobile station PN sequence with respect to a base station PN sequence which is continuously input in real time in order to time the calculation operation of each partial detection energy for the corresponding hypothesis. As the phase shifts, each partial detection energy for the hypothesis corresponding to each phase shift (for example, W = 1 to 4) is calculated and accumulated and stored for each hypothesis. The PN capture circuit shifts the phase to the first hypothesis in the corresponding search window, calculates the next partial detection energy for the hypothesis (W = 1 to 4) corresponding to each phase shift, and accumulates each hypothesis. Perform the save operation. At this time, the phase shift to the first hypothesis in the corresponding search window may be implemented by phase shifting the mobile station PN sequence during the corresponding period in the opposite direction to each phase shift described above.

This results in a time difference between the partial detection energy calculation operation time periods for a given hypothesis, so that even if the received signal falls into fading, the PN capture probability does not decrease, so that the average PN capture time can be shortened.

On the other hand, in the detailed description of the present invention has been described with respect to the embodiment of the serial capture device, various modifications such as application to a parallel capture device and a hybrid capture device is possible without departing from the scope of the present invention, of course. . Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the PN capturing apparatus and method according to the embodiment of the present invention hypothesize corresponding to each phase shift while moving the phase of the mobile station PN sequence with respect to the base station PN sequence which is continuously input in real time within the corresponding search window. Calculate the detected energy for each part and accumulate and store by hypothesis. Then, the phase shift is performed to the first hypothesis in the corresponding search window, and the next partial detection energy for the hypothesis corresponding to each phase shift is calculated, and the accumulation is stored for each hypothesis. As a result, the time interval between the partial detection energy calculation operations for a given hypothesis is mutually different, and even if the received signal falls into fading, the PN capture probability does not decrease, so that the average PN capture time can be shortened.

Claims (13)

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 sequence corresponding to a predetermined hypothesis; A despreader for despreading the input base station P-en sequence into the mobile station P-en sequence; An accumulator for accumulating the output of the despreader for a corresponding integration period; A squarer that squares the output of the accumulator to calculate respective partial detection energies for the given hypothesis; A cumulative storage device for accumulating and storing each partial detection energy for each hypothesis in the search window; A peak detector that detects the largest energy value among the detected energies of each hypothesis that are calculated and accumulated as many times as set per hypothesis; And a controller for controlling the overall operation of the P-N capture device, such as a comparison operation between the largest energy value and a threshold value, and outputting a phase shift control signal to the P-N generator. Capture device. 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 sequence corresponding to a predetermined hypothesis; A despreader for despreading the input base station P-en sequence into the mobile station P-en sequence; An accumulator for accumulating the output of the despreader for a corresponding integration period; A squarer that squares the output of the accumulator to calculate respective partial detection energies for the given hypothesis; A cumulative storage device for accumulating and storing each partial detection energy for each hypothesis in the search window; A peak detector that detects the largest energy value among the detected energies of each hypothesis that are calculated and accumulated as many times as set per hypothesis; A plurality of serial P-en captures comprising a controller for controlling the overall operation of the P-En capture device, such as a comparison operation between the largest energy value and a threshold value, and outputting a phase shift control signal to the P-En generator. P-en capture device, characterized in that the device is configured in parallel. 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 sequence corresponding to a predetermined hypothesis; A despreader for despreading the input base station P-en sequence into the mobile station P-en sequence; An accumulator for accumulating the output of the despreader for a corresponding integration period; A squarer that squares the output of the accumulator to calculate respective partial detection energies for the given hypothesis; A cumulative storage device configured to accumulate and store each partial detection energy for each hypothesis in a corresponding search window by configuring a memory divided into regions for each hypothesis; A peak detector that detects the largest energy value among the detected energies of each hypothesis that are calculated and accumulated as many times as set per hypothesis; And a controller for controlling the overall operation of the P-N capture device, such as a comparison operation between the largest energy value and a threshold value, and outputting a phase shift control signal to the P-N generator. Capture device. 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 sequence corresponding to a predetermined hypothesis; A despreader for despreading the input base station P-en sequence into the mobile station P-en sequence; An accumulator for accumulating the output of the despreader for a corresponding integration period; A squarer that squares the output of the accumulator to calculate respective partial detection energies for the given hypothesis; A cumulative storage device configured to accumulate and store each partial detection energy for each hypothesis in a corresponding search window by configuring a memory divided into regions for each hypothesis; A peak detector that detects the largest energy value among the detected energies of each hypothesis that are calculated and accumulated as many times as set per hypothesis; A plurality of serial P-en captures comprising a controller for controlling the overall operation of the P-En capture device, such as a comparison operation between the largest energy value and a threshold value, and outputting a phase shift control signal to the P-En generator. P-en capture device, characterized in that the device is configured in parallel. In the P-N acquisition method of a mobile communication system using a code division multiple access method, Computing the partial detection energy for the hypothesis corresponding to each phase shift while accumulating and storing the hypothesis corresponding to each phase shift while moving the phase of the mobile station P-N sequence with respect to the inputted base station P-N sequence by the number of hypotheses in the corresponding search window. First course, A second process of performing the first process again by phase shifting the mobile station P-N sequence to the first hypothesis in the corresponding search window; A third process of performing a comparison between the largest energy value and a threshold value among the detected energies of each hypothesis that are calculated and accumulated as many times as set per hypothesis, and A fourth step of performing the first to third steps for a next search window by phase shifting the mobile station P-N sequence if the largest energy value is smaller than a threshold value; P-en capture method characterized in that consisting of. The method of claim 5, wherein the phase shift to the first hypothesis in the corresponding search window of the second process, And phase shifting the mobile station P-N sequence during the interval in the opposite direction to each phase shift. The method of claim 6, wherein during the corresponding interval, P-en capturing method characterized by the following equation (1). The method of claim 7, wherein the second process, If the partial detection energy is not calculated as many as the number of times set for each hypothesis in the corresponding search window, the first process is performed again by phase shifting the mobile station P-N sequence to the first hypothesis in the corresponding search window. P-en capture method. In the P-N acquisition method of a mobile communication system using a code division multiple access method, A first step of shifting a phase of a mobile station P-N sequence with respect to an inputted base station P-N sequence in a corresponding direction and accumulating and storing partial detection energy for a hypothesis corresponding to the phase shift and by hypothesis; A second process of performing the first process again if the hypothesis is not the last hypothesis in the search window; If the hypothesis is the last hypothesis in the search window, it is checked whether the partial detection energy has been calculated for a set number of times for each hypothesis in the search window, and the phase shifted to the first hypothesis in the search window. The third process of performing the second process again, A fourth process of performing a comparison between the highest energy value and a threshold value among the detection energies of each hypothesis calculated and accumulated for each hypothesis; A fifth step of performing the first to fourth steps for the next search window by phase shifting the mobile station P-N sequence when the largest energy value is smaller than a threshold value; P-en capture method characterized in that consisting of. The method of claim 9, wherein the phase shift to the first hypothesis in the corresponding search window of the third process, And phase shifting the mobile station P-N sequence during the interval in the opposite direction of the phase shift. The method of claim 10, wherein during the corresponding interval, P-en capturing method characterized in that corresponds to the following equation (2). The method of claim 11, wherein the third process, If the partial detection energy is not calculated as many times as the set number of times for each hypothesis in the search window, the first process and the second process are performed again by phase shifting to the first hypothesis in the search window. Capture method. The method of claim 12, wherein the P-en capture method, And if the partial detection energy is calculated a predetermined number of times for each hypothesis in the corresponding search window, the fourth process is performed.