KR100788892B1 - Apparatus and method for generating downlink signal, and apparatus and method for searching cell - Google Patents

Abstract

A downlink signal generation device and a cell search device are disclosed.

The downlink signal generating apparatus arranges a cell group identification sequence corresponding to a predetermined cell in a synchronization period of a downlink frame in the frequency domain so that a plurality of repetition patterns are formed in the time domain, and generates a downlink frame in the frequency domain using a time domain signal Convert to The downlink signal generating apparatus generates a downlink signal by multiplying a plurality of orthogonal identification codes constituting the frame synchronization identification sequence from the time domain signal by a plurality of repetition patterns.

The cell search apparatus multiplies the received signal by a frame synchronization identification sequence consisting of two orthogonal recognition codes, correlates the delayed signal of the multiplied signal with the multiplied signal, and finds a point in time when the magnitude of the correlation result is equal to or greater than a predetermined level. Cell search is performed by determining symbol synchronization and frame synchronization.

Frame, Sync, Cell Search, Cell Group, Downlink Signal

Description

Apparatus and method for generating a downlink signal, and apparatus and method for performing cell search {APPARATUS AND METHOD FOR GENERATING DOWNLINK SIGNAL, AND APPARATUS AND METHOD FOR SEARCHING CELL}

1 is a frame structure diagram illustrating an OFDM-based downlink frame according to an embodiment of the present invention.

2 is a frame structure diagram illustrating an OFDM-based sync block according to an embodiment of the present invention.

3 is a frame structure diagram illustrating an OFDM based downlink subframe 12 according to an embodiment of the present invention.

4 is a diagram illustrating bandwidth scalability of a downlink frame according to an embodiment of the present invention.

5 is a diagram illustrating bandwidth scalability of a downlink frame according to another embodiment of the present invention.

6 is a block diagram illustrating a downlink signal generating apparatus 100 according to an embodiment of the present invention.

7 is a flowchart illustrating a downlink signal generation method according to an embodiment of the present invention.

8 illustrates a method of applying a cell group identification sequence and a frame synchronization identification sequence according to an embodiment of the present invention.

9 is a diagram illustrating a method of applying a cell group identification sequence and a frame synchronization identification sequence according to another embodiment of the present invention.

10 is a flowchart illustrating a signal conversion process of a synchronization section according to an embodiment of the present invention.

11 is a block diagram illustrating a mobile station 200 performing a cell search in accordance with an embodiment of the present invention.

12 is a flowchart illustrating a cell searching method according to an embodiment of the present invention.

13 is a block diagram illustrating a synchronization detector 210 according to an embodiment of the present invention.

The present invention relates to an apparatus and method for generating a downlink signal, and to an apparatus and method for performing cell search. In particular, a method for searching for a cell in an orthogonal frequency division multiplexing (OFDM) based cellular system It is about.

The cellular system must be able to synchronize the time synchronization with the frequency synchronization by the terminal to the signal of the base station for the initial synchronization, and also be able to perform cell search. After the terminal synchronizes initially, it should be able to track time and frequency, and it should be able to perform time and frequency synchronization and cell search of neighbor cells for handover.

As a conventional technique for cell searching, two frame structures were proposed in a paper published in IEEE VTC Fall, OFDM Section IV-6 in September 2005. According to the first scheme, one frame is divided into four time blocks, and four time blocks are allocated synchronization recognition information, cell group recognition information, cell unique recognition information, and synchronization recognition information, respectively. On the other hand, according to the second scheme, one frame is divided into four time blocks, the first time block and the third time block are allocated synchronization recognition information and cell unique recognition information, and the second time block and the fourth time block. The block is allocated sync recognition information and cell group recognition information.

According to the first scheme above, since the symbol synchronization is acquired only in the first time block, it is impossible to obtain a fast synchronization within 4.5 ms specified when the terminal is powered on or when handover between heterogeneous networks. In addition, it is difficult to obtain diversity gain through accumulation of synchronization recognition information for fast synchronization acquisition.

On the other hand, according to the second method above, in order to obtain frame synchronization, cell unique recognition information or cell group recognition information must be correlated simultaneously with acquisition of a cell, so that a cell search process is complicated and fast cell search is difficult.

Meanwhile, as another technique for cell searching, a method of acquiring synchronization using a separate preamble and searching for a cell has been proposed, but this method is not applicable to a system in which a preamble does not exist. In addition, since the preamble is placed at the beginning of the frame, when the terminal wants to acquire synchronization at a time position other than the beginning of the frame, there is a problem of waiting for the next frame. In particular, when the terminal performs handoff between GSM mode, WCDMA mode, and 3GPP LTE mode, the initial symbol synchronization should be acquired within 4.5 msec, but the initial symbol synchronization can be obtained within 4.5 msec because synchronization can be obtained in units of frames. Occurs when there is no.

An object of the present invention is to provide a cell search method through fast synchronization acquisition and a downlink signal generation method that enables fast synchronization acquisition.

According to an embodiment of the present invention, an apparatus for generating a downlink signal for a predetermined cell includes a frame generator, a signal converter, and a frame synchronization applier. The frame generation unit generates a downlink frame and arranges a cell group identification sequence corresponding to the predetermined cell in a synchronization period of the downlink frame so that a plurality of repetition patterns are formed in the time domain. The signal converter converts the downlink frame into a time domain signal. The frame synchronization application unit generates a downlink signal by multiplying the plurality of orthogonal identification codes constituting the frame synchronization identification sequence from the time domain signal by the plurality of repetition patterns.

In this case, the frame generation unit generates a downlink frame including a plurality of sync blocks, and generates a cell group identification sequence corresponding to the predetermined cell in a sync period of each sync block so that a plurality of repetitive patterns are formed in a time domain. Can be placed.

In this case, the frame synchronization applying unit may generate the downlink signal with a plurality of frame synchronization identification sequences respectively corresponding to the plurality of sync blocks.

According to another embodiment of the present invention, a method for generating a downlink signal for a predetermined cell includes generating a downlink frame and the predetermined period in a synchronization period of the downlink frame such that a plurality of repetition patterns are formed in a time domain. Disposing a cell group identification sequence corresponding to a cell of the cell; converting the downlink frame into a time domain signal; and a plurality of orthogonal recognition codes constituting a frame synchronization identification sequence in the time domain signal; Generating a downlink signal by multiplying each of the repetition patterns.

According to another embodiment of the present invention, an apparatus for searching for a cell includes a sync detector, a downlink frame extractor, a sync interval multiplier, a signal converter, and a cell group determiner. The synchronization detector multiplies the received signal with a frame synchronization identification sequence consisting of two orthogonal recognition codes, correlates the multiplied signal with the delayed signal of the multiplied signal, and finds a point in time when the magnitude of the correlation result is equal to or greater than a predetermined level. Determine symbol synchronization and frame synchronization. The downlink frame extractor extracts a downlink frame in the time domain based on the symbol synchronization and the frame synchronization. The sync interval multiplier multiplies the sync interval of the downlink frame of the time domain by the frame sync identification sequence. The signal converter converts the downlink frame in the time domain multiplied by the frame synchronization identification sequence into a frame in the frequency domain. The cell group determination unit determines a cell group number by extracting a cell group identification sequence in a synchronization period of a frame of the frequency region.

In this case, the synchronization detector may determine the symbol synchronization and the frame synchronization by correlating the received signal with a plurality of frame synchronization identification sequences respectively corresponding to a plurality of sync blocks included in the downlink frame.

In this case, the synchronization detector may have a plurality of frame synchronization identification sequence groups respectively corresponding to a plurality of cell group sets, and may correlate the received signal to determine the symbol synchronization and frame synchronization and determine a cell group set number.

According to another embodiment of the present invention, a method of searching for a cell is generated by multiplying a received signal by a frame synchronization identification sequence consisting of two orthogonal identification codes, and generating a multiplied signal and multiplying the delayed signal of the multiplied signal by the multiplied signal. Calculating a correlation result by correlating a signal, determining a symbol synchronization and a frame synchronization by finding a time point at which the magnitude of the correlation result is greater than or equal to a predetermined level, and determining frequency synchronization by estimating a phase of the correlation result Extracting a downlink frame in a time domain based on the symbol synchronization, the frame synchronization, and the frequency synchronization; multiplying the frame synchronization identification sequence by a synchronization section of the downlink frame in the time domain; The downlink frame of the time domain multiplied by the frame synchronization identification sequence is a frame of a frequency domain. And extracting a cell group identification sequence in a synchronization period of the frame of the frequency domain to determine a cell group number.

DETAILED DESCRIPTION Hereinafter, exemplary 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. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

In addition, when a part is said to "include" a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated.

Hereinafter, a collection of a plurality of cells is called a cell group, and a collection of a plurality of cell groups is called a cell group set. A cellular system according to an embodiment of the present invention includes a plurality of cell groups, and one cell group includes a plurality of cells. Meanwhile, a cellular system according to another embodiment of the present invention includes a plurality of cell group sets, one cell group set includes a plurality of cell groups, and one cell group includes a plurality of cells.

Next, a structure of an OFDM-based downlink frame according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5.

1 is a frame structure diagram illustrating an OFDM-based downlink frame according to an embodiment of the present invention. In Figure 1 the horizontal axis is the time axis, the vertical axis is the frequency axis or subcarrier (subcarrier) axis.

As shown in FIG. 1, one downlink frame 10 according to an embodiment of the present invention includes four sync blocks 11 with a time interval of 10 msec. One sync block 11 includes five subframes 12 with a time interval of 2.5 msec. One subframe 12 has a time interval of 0.5 msec, and one downlink frame 10 includes a total of 20 subframes 12.

2 is a frame structure diagram illustrating an OFDM-based sync block according to an embodiment of the present invention.

As shown in FIG. 2, one sync block 11 includes five subframes 12, and one subframe 12 includes seven OFDM symbols. As shown in FIG. 2, one sync block 11 according to an embodiment of the present invention includes, but is not limited to, one sync section 13 corresponding to one OFDM symbol section at a start section of the sync block. It doesn't have to be. That is, one sync block 11 may include a sync section 13 in any section within the sync block 11, and may include two or more sync sections 13. According to the embodiment of FIG. 2, the repetition period of the synchronization section 13 is equal to the time occupied by the five subframes 12.

Meanwhile, as shown in FIG. 2, one subframe 12 according to an embodiment of the present invention includes one pilot section 14 including pilot symbols, and one pilot section 14 is 1. Corresponds to the OFDM symbol period, but is not necessarily limited thereto. That is, one subframe 12 may include two or more pilot sections 14. In addition, as shown in FIG. 2, the pilot symbols may be arranged in one OFDM symbol interval according to a time division multiplexing (TDM) structure, but may be arranged in a frequency domain-scattered division multiplexing (SDM) structure. Accordingly, it may be arranged in two or more OFDM symbol intervals.

3 is a frame structure diagram illustrating an OFDM based downlink subframe 12 according to an embodiment of the present invention.

As shown in FIG. 3, the subframe 12 according to the embodiment of the present invention includes a synchronization section 13, a pilot section 14, and a data section 15.

Elements of the cell group identification sequence are arranged at regular intervals in the frequency domain corresponding to the common synchronization channel of the synchronization section 13. According to FIG. 3, elements of the cell group identification sequence are arranged with subcarrier spacing 1. Meanwhile, the cell group identification sequence may be expressed as in Equation 1 below.

In Equation 1, k denotes a cell group number, and N _G denotes a length of a cell group identification sequence. According to an embodiment of the present invention, N _G may mean half of the total number of available subcarriers allocated to the common synchronization channel.

Meanwhile, a Hadamard sequence, a gold sequence, a Golay sequence, a KAZAC sequence, a generalized chirp like (GCL) sequence, a pseudo-noise (PN) sequence, and the like may be used to obtain a cell group identification sequence. An element c _n ^(k) of the cell group identification sequence according to the GCL sequence may be expressed as in Equation 2.

Meanwhile, the cell group identification sequence may be arranged in the frequency domain of the common sync channel as shown in FIG. 3. In the mobile communication system supporting the scaleable bandwidth as shown in Figs. 4 and 5, the mobile station using various bandwidths, such as the mobile station using the bandwidth of 1.25 MHz, the mobile station using the bandwidth of 2.5 MHz, may perform the cell group identification sequence. To receive it. According to an embodiment of the present invention, the common synchronization channel may use a central 1.25 MHz or 5 MHz except for a DC subcarrier. When the frequency domain of the common synchronization channel is 1.25 MHz, the number of subcarriers in the frequency domain is 76, so N _G = 38, thus the number of distinguishable cell groups is 38.

The pilot section 14 includes a pilot symbol and may include a data symbol and a cell identification sequence in addition to the pilot symbol.

The data interval 15 includes data symbols and may include a cell identification sequence.

The cell identification sequence may be arranged in the pilot section 14 or may be distributed in the pilot section 14 and the data section 15 in the time domain and the frequency domain.

Next, a downlink signal generating apparatus 100 according to an embodiment of the present invention will be described with reference to FIGS. 6 to 10.

6 is a block diagram illustrating a downlink signal generating apparatus 100 according to an embodiment of the present invention.

As shown in FIG. 6, the downlink signal generating apparatus 100 includes a downlink frame generator 110, an inverse fast fourier transform (IFFT) calculator 120, a frame synchronization applier 130, and a transmitter 140. It includes.

7 is a flowchart illustrating a downlink signal generation method according to an embodiment of the present invention.

First, the downlink frame generator 110 generates a downlink frame as shown in FIGS. 1 to 3 (S110). That is, the downlink frame generator 110 generates a frame including a plurality of sync blocks, and each sync block includes a sync period 13, and the downlink frame generator 110 is located in the time domain. The cell group identification sequence is arranged in the synchronization section 13 to form a plurality of repeating patterns.

Next, the IFFT calculator 120 performs a fast Fourier inverse transform with the downlink frame generated by the downlink frame generator 110 to generate a signal in the time domain (S120).

The frame synchronization application unit 130 generates a downlink signal by multiplying a plurality of repetition patterns existing in the synchronization period 13 of the signal in the time domain generated by the IFFT operation unit 120 with the frame synchronization identification sequence (S130). When there are two repetition patterns, the frame synchronization application unit 130 generates a downlink signal by multiplying two orthogonal recognition codes by two repetition patterns, respectively. The x-th frame synchronization identification sequence may be represented by Equation 3 below.

As in Equation 3, the x-th frame synchronization identification sequence includes a u-th orthogonal recognition code and a v-th orthogonal recognition code. In other words, the number x of the frame synchronization identification sequence is determined by the combination of the numbers u and v of the two orthogonal identification codes.

On the other hand, the u-th orthogonal identification code and the v-th orthogonal identification code can be expressed as Equation 4 below.

In Equation 4, u and v are numbers of orthogonal recognition codes. N _F is a length of an orthogonal identification code, which is determined by the number of samples corresponding to half of one OFDM symbol interval excluding a guard interval. In order to obtain an orthogonal recognition code, one of a Hadamard sequence, a Gold sequence, a Golay sequence, a GCL sequence, a KAZAC sequence, and a PN sequence may be used.

Meanwhile, the frame synchronization applying unit 130 may apply the same frame synchronization identification sequence to every sync block 11, but may apply a different frame synchronization identification sequence to every sync block 11. Specifically, when the cell group identification sequence and the frame synchronization identification sequence applied to one sync block 11 are represented by (k, x), the arrangement information of the cell group identification sequence and the frame sync identification sequences applied to one frame may be represented by the following equation. It can be expressed as 5. Where k is the number of the cell group identification sequence or the number of the cell group, and x is the number of the frame sync identification sequence.

In Equation 5, k0, k1, k2, and k3 are numbers of cell group identification sequences applied to sync blocks 0 to 3, respectively, and x0, x1, x2 and x3 are frame syncs applied to sync blocks 0 to 3, respectively. Number of the identification sequence. For example, when the downlink signal generating apparatus 100 of the cell group k uses a different frame synchronization identification sequence for each sync block 11, the cell group identification sequence and the frame synchronization identification sequence are [(k, 1), (k, 2), (k, 3), (k, 4)] generates a downlink signal arranged as.

Meanwhile, the frame synchronization application unit 130 may use a frame synchronization identification sequence group common to all cell groups, or may use a different frame synchronization identification sequence group for each set of cell groups. These two embodiments are described in FIGS. 8 and 9.

8 illustrates a method of applying a cell group identification sequence and a frame synchronization identification sequence according to an embodiment of the present invention.

The cellular system assigns every cell a cell number identification sequence, a cell-specific orthogonal code for scrambled common pilot symbols or data symbols. In order to increase the number of distinguishable cells, the cellular system bundles a plurality of cells into one cell group and assigns a cell group identification sequence to each cell group. In such a cellular system, a mobile station recognizes a cell group through a cell group identification sequence after acquiring frame synchronization, and recognizes a specific cell through a cell number identification sequence.

According to FIG. 8, the apparatus 100 for generating downlink signals of all cell groups includes a frame synchronization identification sequence group consisting of four frame synchronization identification sequences ({ G ⁽¹⁾ , G ⁽²⁾ , G ⁽³⁾ , and G ^{(4 )} . ⁾ }). That is, the downlink signal generating apparatus of cell group k generates a downlink signal having configuration information such as [(k, 1), (k, 2), (k, 3), (k, 4)]. .

The mobile station of the cellular system as shown in FIG. 8 can obtain a time domain diversity gain when obtaining frame synchronization. In the frame structure shown in FIGS. 1 to 3, assuming that the start point of the mobile station to acquire frame synchronization is in the middle of sync block 2, the mobile station acquires frame sync in sync block 3, Detect the cell number. In this case, when the cellular system is a synchronization system, all cells of the cellular system simultaneously transmit a frame synchronization identification sequence G ⁽⁴⁾ corresponding to sync block 3, and thus a gain such as a macro diversity gain is generated and received. The mobile station can have very good correlation characteristics.

On the other hand, when the frequency domain corresponding to the common synchronization channel is 1.25 MHz, the number of available subcarriers for the cell group identification sequence is 38. In this case, the number of distinguishable cell groups is 38.

9 is a diagram illustrating a method of applying a cell group identification sequence and a frame synchronization identification sequence according to another embodiment of the present invention.

The cellular system according to FIG. 9 uses three frame synchronization identification sequence groups as shown in Equation 6 below.

The cellular system according to FIG. 9 has three cell group sets. When the number of cell groups distinguishable by the cell group identification sequence is M, the first set is composed of cell group M in cell group 1, and the second set is 2M cell in cell group (M + 1). The third set consists of a cell group of 3M to a cell group of (2M + 1). The first set uses the frame sync identification sequence { G ⁽¹⁾ , G ⁽²⁾ , G ⁽³⁾ , G ⁽⁴⁾ }, and the second set uses the frame sync identification sequence { G ^{(1 ')} , G ^{(2 ')} , G ^(3') , G ^{(4 ')} }, and the third set is frame synchronization identification sequence { G ^{(1 ")} , G ^(2") , G ^{(3 ")} , G ^{(4 ")} }.

If the cellular system uses the cell group identification sequence and the frame synchronization identification sequence as shown in FIG. 9, the diversity gain may be reduced in the cell corresponding to the boundary of the set of cell groups than the cellular system of FIG. 8. However, there is an advantage that the number of distinguishable cell groups can be increased in proportion to the number of frame sync identification sequence groups used.

For example, if the cellular system uses 1.25 MHz as the frequency domain corresponding to the common synchronization channel and uses five frame synchronization identification sequence groups, the number of distinguishable cell groups is 190, 38 times five times.

Subsequently, FIG. 7 is described.

The transmitter 140 converts the downlink signal generated by the frame synchronization application unit 130 into an analog signal, modulates and demodulates the signal, and transmits the demodulated signal to the cell section through the antenna (S140).

10 is a flowchart illustrating a signal conversion process of a synchronization section according to an embodiment of the present invention.

As shown in FIG. 10, the downlink frame generation unit 110 arranges the cell group identification sequence in the synchronization period 13 with a subcarrier interval of 1. In this case, the downlink frame generation unit 110 places a null symbol in the interval between the cell group identification sequences.

As described above, when the synchronization period 13 in which the cell group identification sequence is arranged is inversely fast Fourier transformed, a time domain signal having two repetition patterns is generated as shown in FIG. 10.

The frame synchronization application unit 130 generates a downlink signal by multiplying different orthogonal identification codes by the repetition pattern of the generated time domain signal. In the downlink signal generated according to the embodiment of the present invention, since the frame synchronization identification sequence is applied to the time domain, the mobile station can obtain frame synchronization in the time domain.

The following describes a cell search method and a mobile station 200 performing a cell search according to an embodiment of the present invention with reference to FIGS. 11 to 13.

11 is a block diagram illustrating a mobile station 200 performing a cell search in accordance with an embodiment of the present invention.

As shown in FIG. 11, the mobile station 200 includes a sync detector 210, a downlink frame extractor 230, a sync interval multiplier 240, a fast fourier transform (FFT) calculator 250, and a cell group determiner. 260, a cell number determination unit 270.

12 is a flowchart illustrating a cell searching method according to an embodiment of the present invention.

First, the synchronization detector 210 multiplies a received signal with a frame synchronization identification sequence consisting of two orthogonal recognition codes and performs differential correlation to obtain symbol synchronization, frame synchronization, and frequency synchronization (S210).

Next, the synchronization detector 210 according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 13.

13 is a block diagram illustrating a synchronization detector 210 according to an embodiment of the present invention.

As shown in FIG. 13, the synchronization detector 210 includes a multiplier 211, a differential correlator 212, a comparator 213, and a phase estimator 214. The differential correlation unit 212 includes a delay unit 212-1 and a correlation unit 212-2.

The multiplier 211 multiplies the received signal with a frame synchronization recognition code consisting of two orthogonal recognition codes and outputs the multiplication unit.

The delay unit 212-1 delays and outputs the output signal of the multiplier 211 by a time corresponding to half of the length of the OFDM symbol interval.

The correlator 212-2 correlates the output signal of the multiplier 211 with the output signal of the delay unit 212-1 and outputs a correlation result. In particular, when different frame sync identification sequences are applied to each sync block, the correlation unit 212-2 performs correlation in parallel. Through this, the mobile station 200 may acquire frame synchronization in units of sync blocks. In addition, even when the cellular system uses different frame synchronization identification sequence groups for each cell group set as shown in FIG. 9, the correlation unit 211 performs correlation in parallel. Through this, the mobile station 200 may not only acquire frame synchronization on a sync block basis, but also grasp the set number of the cell group.

The comparison unit 213 calculates the magnitude (magnitude, I ² + Q ² ) of the correlation result output from the correlation unit 212-2 to determine a symbol synchronization by finding a sample time point of which the magnitude of the correlation result is greater than or equal to a certain level. do. In addition, the comparison unit 213 determines the frame synchronization by finding the number of the frame synchronization identification sequence so that the magnitude of the correlation result is equal to or greater than a predetermined level. According to the embodiment of FIG. 8, when the frame synchronization identification sequence number 3 is such that the magnitude of the correlation result is greater than or equal to a certain level, the comparison unit 215 indicates that the sample time point before the two synchronization blocks is frame synchronization. You can check it. According to the embodiment of FIG. 9, the comparator 215 may determine the frame synchronization by finding the frame synchronization identification sequence number so that the magnitude of the correlation result is greater than or equal to a predetermined level, and simultaneously identify the cell group set number. .

The phase estimator 214 estimates the phase of the correlation result output from the correlator 212-2 to obtain frequency synchronization.

As described above, according to an exemplary embodiment of the present invention, the synchronization detector 210 may simultaneously acquire symbol synchronization, frame synchronization, and frequency synchronization through correlation according to the number of frame synchronization identification sequences in the time domain.

12 will be described.

The downlink frame extractor 230 extracts the downlink frame 10 in the time domain from the received signal based on the symbol synchronization detected by the synchronization detector 210, the frame synchronization detected by the frequency synchronization detector 220, and the frequency synchronization detected by the frequency synchronized detector 220. Extract (S230).

The sync interval multiplier 240 finds the sync interval 13 in the downlink frame 10 of the time domain extracted by the downlink frame extractor 230 and multiplies the frame sync identification sequence (S240).

The fast fourier transform (FFT) calculator 250 performs a fast Fourier operation on the downlink frame 10 in the time domain in which the frame synchronization identification sequence is multiplied by the synchronization section 13, and outputs the downlink frame 10 in the frequency domain. (S250).

The cell group determination unit 260 extracts a cell group identification sequence in the synchronization period 13 of the downlink frame 10 in the frequency domain output by the FFT calculator 250 and uses a plurality of cell group identification sequences used by the cellular system. The cell group number is obtained through correlation with (S260).

The cell number determination unit 270 extracts a cell identification sequence distributed in the pilot section 14 or the data section 15 to obtain a cell number (S270). According to the embodiment of FIG. 8, the cell number determination unit 270 may identify the cell through the cell group number and the cell number obtained by the cell group determination unit 260. According to the embodiment of FIG. 9, the cell number determination unit 270 may further identify the cell using the set number of the cell group obtained by the correlator 212-2. The cell number determination unit 270 may demodulate the broadcast channel (BCH) to verify whether the cell identification sequence included in the broadcast channel is identical to the extracted cell identification sequence and verify the extracted cell identification sequence.

The embodiments of the present invention described above are not implemented only through the apparatus and the method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded. Implementation may be easily implemented by those skilled in the art from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

According to an embodiment of the present invention, since the downlink signal generating apparatus divides one frame into a plurality of sync blocks and arranges different frame sync identification sequences for each sync block, the mobile station can perform fast sync acquisition and cell search. Can be.

In addition, according to an embodiment of the present invention, since the downlink signal generation apparatus applies the frame synchronization identification sequence to the time domain, the mobile station can acquire the frame synchronization before performing the FFT, thereby enabling fast synchronization acquisition.

In addition, according to an embodiment of the present invention, since the cellular system regroups the cell groups and allocates the frame synchronization identification sequence group, the cell group distinguishable by interlocking the cell group identification sequence in the frequency domain and the frame synchronization identification sequence in the time domain The number of s increases and the mobile station can obtain a macro diversity gain.

Claims (8)

In the method for generating a downlink signal for a predetermined cell, Generating a downlink frame; Disposing a cell group identification sequence corresponding to the predetermined cell in a synchronization period of the downlink frame such that a plurality of repetition patterns are formed in a time domain; Converting the downlink frame into a time domain signal; And generating a downlink signal by multiplying the plurality of orthogonal identification codes constituting a frame synchronization identification sequence in the time domain signal by the plurality of repetition patterns, respectively. The method of claim 1, The downlink frame includes a plurality of sync blocks, Disposing the cell group identification sequence comprises disposing a cell group identification sequence corresponding to the predetermined cell in a synchronization period of each sync block such that a plurality of repetition patterns are formed in a time domain. The method of claim 2, Generating the downlink signal includes generating the downlink signal with a plurality of frame synchronization identification sequences corresponding to the plurality of sync blocks, respectively. The method of claim 3, The generating of the downlink signal includes generating the downlink signal with a frame synchronization identification sequence group corresponding to the predetermined cell among a plurality of frame synchronization identification sequence groups for grouping cell groups. In a method for searching a cell, Generating a multiplied signal by multiplying a frame synchronization identification sequence consisting of two orthogonal identification codes by a received signal, and calculating a correlation result by correlating a delayed signal of the multiplied signal with the multiplied signal; Determining symbol synchronization and frame synchronization by finding a time point at which the magnitude of the correlation result is equal to or greater than a predetermined level; Estimating the phase of the correlation result to determine frequency synchronization; Extracting a downlink frame in a time domain based on the symbol synchronization, the frame synchronization, and the frequency synchronization; Multiplying the frame sync identification sequence by the sync section of the downlink frame in the time domain; Converting the downlink frame in the time domain multiplied by the frame sync identification sequence into a frame in a frequency domain; And extracting a cell group identification sequence in a synchronization period of the frame in the frequency domain to determine a cell group number. The method of claim 5, Calculating the correlation result Calculating the correlation result with a plurality of frame synchronization identification sequences respectively corresponding to a plurality of sync blocks included in the downlink frame; The determining of the frame synchronization And determining the frame synchronization through the number of the frame synchronization identification sequence such that the magnitude of the correlation result is equal to or greater than the predetermined level. The method of claim 6, Calculating the correlation result Calculating the correlation result with a plurality of frame synchronization identification sequence groups respectively corresponding to a plurality of cell group sets, Identifying a cell group set number through a frame sync identification sequence group such that the magnitude of the correlation result is greater than or equal to the predetermined level. The method of claim 7, wherein Extracting a cell number identification sequence from the sync block to detect a cell number; Identifying said cell via said cell group set number and said cell group number and said cell number.

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