KR20120038773A - Method for acquiring initial synchronization in code division multiple access system and apparatus thereof - Google Patents

Abstract

PURPOSE: An initial synchronization acquiring method in a CDMA(Code Division Multiple Access) system and apparatus thereof are provided to minimize dwell time for processing correlation by checking the influence of a channel for a diffusion signal. CONSTITUTION: In case the correlation energy value of a search mode is bigger than a first critical level, an initial synchronization acquiring apparatus compares correlation energy values of a verification mode with a second critical level(S270). In case big energy values are more than reference numbers in the correlation energy value of the confirmation mode, the initial synchronization acquiring apparatus acquires synchronization from a PN(Pseudo Noise) code(S300, S310).

Description

METHOD FOR ACQUIRING INITIAL SYNCHRONIZATION IN CODE DIVISION MULTIPLE ACCESS SYSTEM AND APPARATUS THEREOF}

The present invention relates to a method and apparatus for initial synchronization acquisition in a CDMA system, and more particularly, to a CDMA system capable of performing synchronization acquisition quickly and efficiently according to SNR and channel influence without adding additional hardware. An initial synchronization acquisition method and apparatus therefor.

In general, in a mobile communication system, a terminal must first acquire synchronization in order to communicate with a base station. If a signal is transmitted and received in a state in which synchronization acquisition is not performed first, the signal transmitted and received only acts as an interference signal or noise between the terminal and the base station and cannot acquire any information. Therefore, initial synchronization acquisition between the terminal and the base station in all mobile communication systems is a very important factor.

In addition, a receiving end of a base station and a terminal of a code division multiple access (CDMA) system exchanges pilot channels with each other, and initially synchronizes, and spread signals are carried on a pilot channel, and the spread signals are pseudo noise codes. The initial synchronization is obtained when the noise code, hereinafter referred to as the " PN code "

In particular, the double-dwell serial search (DDSS) method

Reduce acquisition time by discarding misalignment between the received signal and the PN code. Average code sync acquisition time depends on signal-to-noise ratio (SNR), channel environment, threshold value and correlation length, and post-integration number.

Depending on how you set each parameter, performance can be affected.

The conventional double-dwell serial search (DDSS) algorithm is classified into a search mode and a verification mode. Correlation energy of the i th code phase in search mode

Energy is calculated on an I-Q noncoherent active correlator with a simple hardware structure and low power consumption and sent to an energylevel detector.

In the existing DDSS, performance depends largely on which threshold value is applied. Generally, the threshold value varies depending on the channel environment and SNR. However, since the receiver does not obtain information about the SNR until the initial synchronization is obtained, the receiver does not actively cope with the change of the SNR. Therefore, according to the Neyman-Pearson test method, it is fixed to a threshold obtained at a specific SNR (typically the lowest SNR at which the receiver is expected to operate) and applied to the entire SNR as it is. This method has a disadvantage in that performance is dramatically degraded in an actual communication environment in which SNR is flexible.

In addition, there is an automatic censoring algorithm to solve this problem and to shorten the initial synchronization acquisition time. The automatic judgment technique uses a correlator to estimate the level of noise and adjusts the threshold accordingly. This method sets a relatively low threshold in a low noise environment and uses a high threshold in a noisy environment such as a Rayleigh environment. It also improves initial acquisition time performance by adjusting the correlation length according to the estimated noise level. However, the complexity of the hardware is increased because a separate correlator for estimating the noise level is added, and a code having zero correlation with the currently received PN code interval has to be made and applied, which is practically limited.

Also, in order to solve the problems of the prior art, a method of setting a plurality of threshold levels and differently setting correlation conditions and threshold conditions for each of the threshold levels has also been proposed. However, there is a case in which a time is delayed in setting a plurality of threshold levels. As a result, there is a problem in that it impedes rapid synchronization.

The problem to be solved by the present invention provides an initial synchronization acquisition method and apparatus including a predump mode that can perform the synchronization acquisition quickly and efficiently according to the SNR and channel influence without adding additional hardware.

In the CDMA system according to an embodiment of the present invention for solving this problem, the initial synchronization acquisition method, receiving a spread signal from the base station, while shifting the PN code M times in the first phase to the M-th phase Calculating a correlation energy value for each phase, determining a maximum value among correlation energy values for each of the M phases as a correlation energy value in a predump mode, and using the correlation energy value in the predump mode to obtain a correlation energy value. Setting a first threshold level and a second threshold level, calculating a correlation energy value in a search mode and a correlation energy value in a confirmation mode using one of the M phases, and correlation in the search mode Comparing the energy value with the first threshold level, wherein the correlation energy value in the search mode is Comparing the correlation energy values in the confirmation mode with the second threshold level if greater than a first threshold level, and the correlation energy value greater than the second threshold level among the correlation energy values in the confirmation mode is a reference number. In the case of the above, the step of acquiring synchronization from the PN code of the corresponding phase.

When the correlation energy value in the search mode is smaller than the first threshold level or the correlation energy value larger than the second threshold level among the correlation energy values in the confirmation mode is less than the reference number, the PN code is M +. Shifting the M phase from the first phase to the 2M th phase over M times, and calculating a correlation energy value for each of the M + 1 th phase to the 2M th phase while the PN code is shifted through the M times; Can be.

The PN code may be cyclically shifted.

The first threshold level and the second threshold level may be expressed as follows, respectively.

Θ _s and θ _v are the first threshold level and the second threshold level, respectively, τ _S and τ _V are the scale indices in the seek mode and the verify mode, respectively, and e _{i , P} are the Correlation energy values are shown.

The correlation energy value in the search mode and the correlation energy value in the confirmation mode may be calculated using a first phase among the M phases.

The calculating of the correlation energy values in the predump mode, the search mode, and the confirmation mode may be calculated using the correlation length and the post-integral fraction in the predump mode, the search mode, and the confirmation mode.

A computer-readable medium according to an embodiment of the present invention records a program for causing a computer to execute any one of the above methods.

An initial synchronization acquisition device in a CDMA system according to another embodiment of the present invention includes a signal receiver for receiving a spread signal from a base station, a PN code generator for sequentially shifting a PN code, and the PN code is shifted over M times. The correlation energy value is calculated for each of the M phases from the first phase, and then the maximum value is determined as the correlation energy value in the predump mode, and the correlation in the search mode using one of the M phases. A correlation energy detector configured to calculate an energy value and a correlation energy value in the confirmation mode, a threshold level setting unit configured to set a first threshold level and a second threshold level using the correlation energy values in the predump mode, and in the search mode A searcher for comparing the correlation energy value of the first threshold level with the correlation energy value in the search mode If greater than the first threshold level, a verification unit for comparing the correlation energy values in the confirmation mode with the second threshold level, and the correlation energy value greater than the second threshold level among the correlation energy values in the confirmation mode is In the case of more than the reference number, a synchronization unit for obtaining synchronization from a PN code of a corresponding phase is included.

When the correlation energy value in the search mode is smaller than the first threshold level or the correlation energy value larger than the second threshold level among the correlation energy values in the confirmation mode is less than the reference number, the PN code generator may include: The PN code is shifted M times from the M + 1 th phase to the 2 M th phase, and the correlation energy detector is configured for each of the M + 1 th phase to the 2 M th phase while the PN code is shifted through the M times. The correlation energy value can be calculated.

Thus, according to the present invention, by including a predump mode for presetting the threshold level of the search mode and the confirmation mode, it is possible to check only how much the received spread signal is affected by the channel, that is, the SNR, correlation processing The integration time (dwell time) can be minimized. In addition, by flexibly changing the synchronization acquisition condition, the synchronization acquisition time is shortened and the probability of error occurrence is reduced in changing SNR and channel environments. In addition, power consumption may be minimized by performing synchronization acquisition using existing hardware without adding a filter and a correlator.

1 is a block diagram of an initial synchronization acquisition device in a CDMA system according to an embodiment of the present invention.
2 is a flowchart illustrating an initial synchronization acquisition method in a CDMA system according to an embodiment of the present invention.
3 is a diagram illustrating a process of shifting a PN code according to an embodiment of the present invention.
4 is a block diagram of an initial synchronization acquisition device for explaining FIG. 2.
5 is a diagram for describing a process of obtaining a correlation energy value through a spread signal and a PN code.
6A to 6C are diagrams for describing a method of a confirming unit comparing a correlation energy value and a threshold level in a confirmation mode according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

1 is a block diagram of an initial synchronization acquisition device in a CDMA system according to an embodiment of the present invention. As shown in FIG. 1, the initial synchronization acquisition device 100 includes a signal receiver 110, a correlation energy detector 120, a PN code generator 130, a threshold level setting unit 140, and a searcher 150. , The verification unit 160 and the synchronization unit 170.

The signal receiving unit 110 receives a spread signal from a base station. The spread signal represents a signal obtained by spreading an original signal into a wider band using a PN code in a code division multiple access (CDMA) system.

The correlation energy detector 120 may include a plurality of multipliers, integrators, or IQ noncoherent active correlators, and multiplies and integrates a spread signal and a PN code signal of a specific phase to perform a predump mode, The correlation energy values in the seek mode and confirm mode are calculated. The correlation energy detector 120 obtains correlation energy values for M phases formed by sequentially shifting the PN codes.

The PN code generator 130 generates a PN code sequence based on a code having a reference phase. The PN code generator 130 generates the PN code shifted to the next phase when the threshold condition is not satisfied in the search mode or the confirm mode.

The PN code generator 130 shifts the PN code from the first phase to the Mth phase so that the correlation energy detector 120 calculates correlation energy values for M phases (M is a natural number). . When the threshold condition is not satisfied in the search mode or the verify mode, the correlation energy detector 120 shifts the PN code from M + 1 th to 2M th phases as the next phases, and correlates the M energy with respect to M phases. Find the value.

The threshold level setting unit 140 determines the threshold level θs in the search mode and the threshold level θv in the confirmation mode. The mode in which the threshold level setting unit 140 determines the threshold levels θ s and θ v is called a “pre-dump mode” for convenience. The threshold level setting unit 140 receives the correlation energy values e _{i and p} in the predump mode from the correlation energy detector 120, where the correlation energy values e _{i and p} are obtained for M phases. One of the correlation energy values is set to the maximum value.

Then, the threshold level setting unit 140 obtains the threshold levels θs and θv using the selected correlation energy values e _{i and p} , and determines the determined threshold levels θs and θv by the searcher 150 and the confirmation unit. Transmit to 160, respectively. In the predump mode, it is possible to set a short dwell time for correlation processing because it checks only how much the received spread signal is affected by the channel, that is, the SNR.

The searcher 150 receives a correlation energy value e _{i , s} in the i-th code phase from the correlation energy detector 120. In particular, when the correlation energy detector 120 obtains the correlation energy values e _{i , s} for the M th phases from the first phase, the searcher 150 searches the correlation energy values e _{i , s} in the first phase. and delivered to, as M + 1 If to obtain the correlation energy value (e _{i, s)} with respect to the 2M-th phase from the second phase, the search for correlation energies (e _{i, s)} at the M + 1-th phase unit (150 To pass). The mode in which the search unit 150 compares the correlation energy values e _{i and s} with the threshold level θ s is called a “search mode” for convenience. That is, the search mode refers to a mode that primarily determines whether synchronization can be acquired using a PN code and a spread signal.

If the correlation energy value e _{i , s} in the search mode is larger than the threshold level θ s, the process proceeds to the verify mode. If the correlation energy value e _{i , s} is smaller than the threshold level θ s, the PN code generator 130 starts from the M + 1 th phase. Shift the PN code sequentially up to the 2M th phase.

The verification unit 160 receives the correlation energy values e _{i and v} in the i-th code phase from the correlation energy detector 120, and determines the correlation energy values e _{i and V} in the confirmation mode at the threshold level θ. _v ). If, as in the search section 150, correlation energy detection section 120 from the first phase to obtain the correlation energy value (e _{i, V)} with respect to the M-th phase, the correlation energy value of the first phase (e _{i, V} ) Is transmitted to the searcher 150. Similarly, when the correlation energy values e _{i and s are} obtained for the M + 1 th phase to the 2M th phase, the correlation energy values e _{i , s} ) is transmitted to the search unit 150. The mode in which the verification unit 160 compares the correlation energy values e _{i and v} and the threshold level θ _v is called a 'verification mode' for convenience. That is, the confirmation mode refers to a mode in which the searcher 150 secondarily determines whether synchronization acquisition is possible with respect to a signal primarily determined that synchronization acquisition is possible.

Ten thousand and one from a plurality of correlation energies (e _{i, V)} to from a threshold level (θ _v), large correlation energies than (e _{i, V)} not less than the number of the standard, the synchronization unit 170 PN code in the acknowledgment mode The synchronization is obtained and the subsequent PN code is tracked. On the other hand, a plurality of correlation energies (e _{i, V)} to from a threshold level (θ _v) large correlation energies (e _{i, V)} is the reference number, the corresponding phase (i.e., the first from the M second phase is less than than The PN code generator 130 sequentially shifts the PN code from the M + 1 th phase to the 2M th phase, by determining that the spread signal having the largest correlation energy value has not obtained initial synchronization.

Hereinafter, an initial synchronization acquisition method in a CDMA system will be described in more detail with reference to FIGS. 2 to 5. 2 is a flowchart illustrating a method for initial synchronization acquisition in a CDMA system according to an embodiment of the present invention, and FIG. 3 is a view for explaining a process of shifting a PN code according to an embodiment of the present invention. 4 is a block diagram of an initial synchronization acquisition apparatus for explaining FIG. 2. 5 is a diagram for describing a process of obtaining a correlation energy value through a spread signal and a PN code.

First, the signal receiver 110 receives a spread signal r (t) by CDMA from a base station (S210). The PN code generator 130 generates a PN code sequence based on a code having a reference phase (for convenience of description, setting the reference phase as the first phase) and performing M times from the first phase to the Mth phase. Shift the PN code (S220).

A process of shifting the PN code will be described in more detail with reference to FIG. 3. As shown in the left figure of FIG. 3, the spread signal r (t) and the PN code sequence are composed of V bits (0 to V-1). In the first phase Phase 1, it is assumed that bit numbers are the same. Here, when a failure alarm is generated, the PN code is shifted to the second phase (Phase 2). As shown in the right figure of FIG. 3, the PN code is cyclically shifted so that the V-1 th bit, which was the most backward, is 0. Go to the first bit.

While the PN code generator 130 shifts the PN code from the first phase to the Mth phase, the correlation energy detector 120 obtains the correlation energy values e _{i and m for} each of the M phases ( S230).

As shown in FIGS. 2 and 4, the correlation energy detector 120 uses a correlation length N _{W and M} and a post integration length Lm for each of the M phases. Calculate the value e _{i , m} . That is, as shown in FIG. 4, the received spread signal r (t) is divided into cosω _c (t), which is an I component, and sinω _c (t), which is a Q component, and I and Q components are respectively divided by I of the PN code. After correlating with the component PN _I and the Q component PN _Q of the PN code, the components are integrated corresponding to the correlation lengths N _{W and M} , respectively. In addition _{, a} correlation energy value (e _{i , m} ) may be obtained for each of the M phases by integrating the sum (z _{l , m} ) of squares of the integrated values by the post integration integral (Lm).

5 illustrates an example of a spread signal and a PN code in which correlation lengths N _{W and M} are 3 and post-integral fraction Lm is 2. The correlation energy detector 120 performs an integral operation by correlating three bit signals corresponding to the correlation lengths N _{W and M} , respectively, and then integrates the two groups corresponding to the post-integral integral Lm again. do.

As such, the correlation energy detector 120 receives the correlation lengths N _{W and P} and the post-integral fraction L _{P in} the predump mode from the threshold level setting unit 140 and correlates each of the M phases. Find the energy values (e _{i , m} ). The correlation energy detector 120 determines a maximum value among correlation energy values for each of the M phases as the correlation energy values e _{i and P} in the predump mode, and calculates the calculated correlation energy values e _{i and P.} Is transmitted to the threshold level setting unit 140. In addition, the correlation energy detector 120 receives the cumulative lengths N _{W and S} and the post-integral fraction L _S in the search mode from the searcher 150, and correlates a correlation energy value with respect to one of the M phases. (e _{i , S} ) is calculated and the calculated correlation energy values e _{i , S} are transmitted to the searcher 150. In addition, the correlation energy detector 120 receives the cumulative lengths N _{W and V} and the post-integral fraction L _V in the confirmation mode from the verification unit 160 and performs a plurality of correlations on one of the M phases. The energy values e _{i and V} are calculated, and the calculated plurality of correlation energy values e _{i and V} are transmitted to the verification unit 160 (S240). The correlation energy detector 120 may detect the correlation energy values e _{i , S} , e _{i , and V} for the first phase among the M phases.

The threshold level setting unit 140 determines the threshold level θ _s in the search mode and the threshold level θ _v in the confirmation mode (S250). That is, the threshold level setting unit 140 uses the correlation energy values e _{i and P} in the predump mode as shown in Equation 1 below to determine the threshold level θ _s in the search mode and the confirmation mode. Determine the threshold level θ _v .

Here, τ _S and τ _V represent scale indices for obtaining threshold values of the search mode SM and the confirm mode VM, respectively. Since the scale indices τ _S and τ _V are influenced by the SNR and the channel, it is difficult to find an ideal value. A method of setting the scale indices τ _S and τ _V will be described later with reference to FIG. 7.

In addition, the threshold level setting unit 140 determines the threshold level θ _s in the search mode and the threshold level θ _v in the verify mode, which are determined as in Equation 1, respectively. Transfer to (S260).

The searcher 150 compares the threshold level θ _s with the correlation energy values e _{i and S} in the search mode (S270), and if the threshold level θ _s is the correlation energy value e in the search mode, _{i , S} ), it is determined that the spread signal of the corresponding phase has not obtained the initial synchronization, and generates a failure alarm (S280). Then, the PN code generator 130 shifts the PN code to the M + 1 th phase, and then, based on the PN code having the M + 1 th phase, as described in S220, the 2M th phase from the M + 1 th phase. The PN code is sequentially shifted over M times (S290).

As described in S230, while the PN code generator 130 shifts the PN code from the M + 1 th phase to the 2M th phase, the correlation energy detector 120 performs a correlation energy value e _{i for} each of the M phases. _{, m} ) In addition, the processes of S240 to S270 are repeatedly performed, and the descriptions of steps S240 to S270 have been described above, and thus redundant descriptions thereof will be omitted.

On the other hand, if the threshold level θ _s is greater than the correlation energy values e _{i and S} in the search mode, the verification unit 160 determines the correlation energy values e _{i and V} and the threshold level (in the confirmation mode). θ _v ) is compared (S300).

The identification unit 160 receives a plurality of correlation energy values e _{i and V} from the correlation energy detector 120 and a correlation greater than the threshold level θ _v among the plurality of correlation energy values e _{i and V.} If the energy values e _{i and V} are greater than or equal to the reference number, it is determined that the spread signal of the corresponding phase has obtained initial synchronization (S310). In operation S320, code tracking is performed based on the initially synchronized spread signal and decoding is performed.

On the other hand, if less than the threshold level (θ _v) large correlation energies (e _{i, V)} number of the reference one among a plurality of correlation energies (e _{i, V)} is the spread signal of the phase could not obtain an initial synchronization In operation S280, a failure alert is generated. The PN code generator 130 shifts the PN code in the M + 1 th phase, and then sequentially shifts the PN code M times from the M + 1 th phase to the 2M th phase, as described in S290. And the process of S230 to S270 is repeated.

Hereinafter, the method of comparing the correlation energy values e _{i and V} and the threshold level θ _v in the confirmation mode will be described in more detail with reference to FIGS. 6A to 6C.

6A to 6C are diagrams for describing a method of a confirming unit comparing a correlation energy value and a threshold level in a confirmation mode according to an exemplary embodiment of the present invention.

First, as shown in FIG. 6A, the spread signal r (t) received from the base station is composed of four samples, each sample having four correlation lengths (N _{W , M} ) and two post-integral fractions (Lm). Assume that it is done. The correlation energy detector 120 then correlates the received spread signal r (t) with the PN code sequence to generate four correlation energy values. 6A to 6C illustrate four correlation energy values (e _{i , V, 1} , e _{i , V, 2} , e _{i , V, 3} , e _{i, V, 4} ) for convenience of description.

Meanwhile, for convenience of description, the verification unit 160 may correlate two or more of four correlation energy values e _{i , V, 1} , e _{i , V, 2} , e _{i, V, 3} , e _{i , V, 4} . It is assumed that only when the energy value is greater than the threshold level θ _v , it is determined that the spread signal of the phase has acquired initial synchronization.

That is, the four correlation energy value as shown in Figure 6b (e _{i, V, 1,} e _{i, V, 2,} e _{i, V, 3,} e _{i, V 4)} of the two correlation energies (e _{i, When V, 1} , e _{i , V, 3} ) is greater than the threshold level θ _v , the identification unit 160 determines that the spread signal of the phase has acquired initial synchronization. On the other hand, the four correlation energies as shown in Figure 6c (e _{i, V, 1,} e _{i, V, 2,} e _{i, V, 3,} e _{i, V 4)} from one correlation energies (e _{i, If} only _{V, 3} is greater than the threshold level θ _v , the identification unit 160 considers that the spread signal of the phase has failed to acquire the initial synchronization.

As described above, in the verification mode, the process proceeds to the next step S310 only when the correlation energy values e _{i and V} larger than the threshold level θ _v are among the plurality of correlation energy values e _{i and V.} More precisely, the initial synchronization of the spread signal can be obtained.

As described above, according to the exemplary embodiment of the present invention, the correlation energy values e _{i and P} obtained through the predump mode are used to determine the threshold levels θ _s and θ _v of the search mode and the confirmation mode. It can be used to obtain early rejection determination in the search mode and confirm mode, thereby greatly reducing the initial synchronization acquisition time. In other words, according to an embodiment of the present invention, by including a predump mode for presetting the threshold levels θ _s and θ _v of the seek mode and the confirm mode, the received spread signal is affected by the channel, that is, the SNR. Only the received data can be checked to minimize the dwell time for correlation processing.

In addition, according to an embodiment of the present invention, by changing the synchronization acquisition conditions in a fluid manner, the synchronization acquisition time is shortened and the probability of error occurrence is reduced in a changing SNR and channel environment. In addition, power consumption may be minimized by performing synchronization acquisition using existing hardware without adding a filter and a correlator.

Meanwhile, according to an embodiment of the present invention, at least two of correlation energy values in the predump mode, the search mode, and the confirmation mode may have the same value.

Embodiments of the present invention include a computer-readable medium having program instructions for performing various computer-implemented operations. This medium records a program for executing the initial synchronization acquisition method in the CDMA system described so far. The medium may include program instructions, data files, data structures, etc., alone or in combination. Examples of such media include magnetic media such as hard disks, floppy disks and magnetic tape, optical recording media such as CDs and DVDs, floppy disks and program commands such as magnetic-optical media, ROM, RAM, flash memory, and the like. Hardware devices configured to store and perform such operations. Alternatively, the medium may be a transmission medium such as an optical or metal wire, a waveguide, or the like including a carrier wave for transmitting a signal specifying a program command, a data structure, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

100: initial synchronization acquisition device, 110: signal receiving unit,
120: correlation energy detector, 130: PN code generator,
140: threshold level setting unit, 150: search unit,
160: confirmation unit, 170: synchronization unit

Claims (12)

Receiving a spread signal from a base station,
Shifting the PN code through M times to calculate a correlation energy value for each of the first to Mth phases,
The maximum value among the correlation energy values for each of the M phases is determined as a correlation energy value in a predump mode, and a first threshold level and a second threshold level are set using the correlation energy value in the predump mode. step,
Calculating a correlation energy value in a search mode and a correlation energy value in a confirmation mode using one phase among the M phases,
Comparing the correlation energy value in the search mode with the first threshold level,
If the correlation energy value in the search mode is greater than the first threshold level, comparing the correlation energy values in the confirmation mode with the second threshold level, and
And obtaining a synchronization from a PN code of a corresponding phase when a correlation energy value larger than the second threshold level among the correlation energy values in the confirmation mode is equal to or greater than a reference number. The method of claim 1,
When the correlation energy value in the search mode is smaller than the first threshold level or the correlation energy value larger than the second threshold level among the correlation energy values in the confirmation mode is less than the reference number,
Shifting the PN code M times from an M + 1 th phase to a 2 M th phase,
Calculating correlation energy values for each of the M + 1 th phase to the 2M th phase while the PN code is shifted over M times. The method of claim 2,
And the PN code is cyclically shifted. The method of claim 2,
Wherein the first threshold level and the second threshold level are each expressed as follows:

Θ _s and θ _v are the first threshold level and the second threshold level, respectively, τ _S and τ _V are the scale indices in the seek mode and the verify mode, respectively, and e _{i , P} are the Correlation energy values are shown. The method of claim 2,
And a correlation energy value in the search mode and a correlation energy value in the verify mode are calculated using a first phase of the M phases. The method of claim 2,
Computing the correlation energy value in the predump mode, the search mode and the confirmation mode,
The initial synchronization acquisition method in the CDMA system that is calculated using the correlation length and the post-integral fraction in the predump mode, search mode and confirmation mode. A computer readable medium having recorded thereon a program for causing a computer to execute the method of any one of claims 1 to 6. A signal receiver for receiving a spread signal from a base station,
PN code generation unit for sequentially shifting the PN code,
While the PN code is shifted over M times, a correlation energy value is calculated for each of the first to Mth phases, and then the maximum value is determined as the correlation energy value in the predump mode, and one of the M phases is determined. A correlation energy detector for calculating a correlation energy value in a search mode and a correlation energy value in a confirmation mode by using a phase of
A threshold level setting unit configured to set a first threshold level and a second threshold level by using the correlation energy value in the predump mode;
A searcher for comparing the correlation energy value in the search mode with the first threshold level;
A confirmation unit comparing the correlation energy values in the confirmation mode with the second threshold level when the correlation energy value in the search mode is greater than the first threshold level, and
And a synchronization unit for obtaining synchronization from a PN code of a corresponding phase when a correlation energy value greater than the second threshold level among the correlation energy values in the confirmation mode is included. The method of claim 8,
When the correlation energy value in the search mode is smaller than the first threshold level or the correlation energy value larger than the second threshold level among the correlation energy values in the confirmation mode is less than the reference number,
The PN code generation unit,
The PN code is shifted M times from the M + 1 th phase to the 2 M th phase,
The correlation energy detector,
And obtaining a correlation energy value for each of the M + 1 th phase to the 2M th phase while the PN code is shifted over M times. 10. The method of claim 9,
An initial synchronization acquisition device in a CDMA system, wherein the first threshold level and the second threshold level are each expressed as follows:

Θ _s and θ _v are the first threshold level and the second threshold level, respectively, τ _S and τ _V are the scale indices in the seek mode and the verify mode, respectively, and e _{i , P} are the Correlation energy values are shown. 10. The method of claim 9,
And a correlation energy value in the search mode and a correlation energy value in a confirmation mode are calculated using a first phase of the M phases. 10. The method of claim 9,
The correlation energy detector,
And a correlation energy value in the predump mode, the search mode, and the verify mode using the correlation length and the post-integral function in the predump mode, the search mode, and the verify mode.

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