JP2008263576A - Cell search method, base station device, and mobile station device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance cell search performance as a whole without reducing scramble code detection performance at a sector end even when using a plurality of primary synchronization codes (PSCs). <P>SOLUTION: In a cell search method in a wireless communication system using a plurality of PSCs as a primary synchronization channel (P-SCH) for each sector, a plurality of PSCs are set such that a part of each PSC becomes common, either the common one part of the plurality of PSCs or any PSC is selected, and propagation path estimation is performed using either the common one part of the plurality of PSCs or any one PSC. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cell search method, a base station apparatus, and a mobile station apparatus, and more particularly to a synchronization channel (SCH) included in a downlink (downlink transmission) signal of cellular mobile communication employing a multicarrier communication system. The present invention relates to a cell search method, a base station apparatus, and a mobile station apparatus that improve cell search performance by using the same.

  In recent years, the third generation mobile communication (3G) including the W-CDMA system has become widespread worldwide, and the fourth generation that realizes a communication speed of 100 Mb / s to 1 Gb / s in the downlink. Mobile communication (4G) is being studied. In addition, in order to smoothly transition from the 3rd generation (3G) to the 4th generation (4G), a communication system with high compatibility with 4G new technology was introduced while using the 3G frequency band. The standardization of E-UTRA (Evolved-UTRA), which speeds up communication, is also in progress.

  In a mobile communication system, a mobile station needs to detect a base station to which the mobile station is to connect and an antenna of the base station for initial synchronization establishment or for handover. In this way, the time synchronization performed for establishing a connection with the base station with which the mobile station is to communicate, that is, the work for adjusting the timing for accurately receiving the communication frame transmitted from the base station, The operation of acquiring information such as communication parameters required for communication with a base station is generally called “cell search”. Normally, cell search is performed from time synchronization. Even after the connection with the base station is established, synchronization is maintained using a known signal (for example, SCH) by the same method as the cell search.

  For example, the cell search in the third generation mobile communication using the W-CDMA system is executed by a method divided into three steps called a three-stage cell search. In the three-stage cell search, generally, a synchronization channel (SCH) and a common pilot channel (CPICH) are first used to detect the reception timing of the SCH (first stage), and then the SCH code. The frame timing and the scramble code group are identified by the correlation detection (second stage), and then the scramble code is identified by the correlation detection using the CPICH (third stage). ing.

  In addition, in E-UTRA, which is the next-generation mobile communication standard, OFDM (Orthogonal Frequency Division Multiplexing) is used as a modulation method, but the cell search follows the above-described three-stage cell search concept. Have been proposed (see, for example, Non-Patent Document 1).

  In Non-Patent Document 1, time synchronization is performed by a first synchronization channel (P-SCH) in a three-stage cell search in a multicarrier communication scheme (using an OFDM communication scheme). A code (PSC: Primary Synchronization Code) known by the base station and the mobile station is assigned to the P-SCH and transmitted from the base station.

  Furthermore, information such as communication parameters is acquired from a second synchronization channel (S-SCH) and a common reference signal (C-RS) corresponding to a W-CDMA CPICH.

  In addition, a plurality of types of PSCs are arranged so as not to interfere with each other between adjacent cells (3 cell reuse), and a time synchronization and initial connection information acquisition to a desired base station can be performed accurately, that is, a cell search can be performed. -A SCH structure has also been proposed.

  In Non-Patent Document 2 and Non-Patent Document 3, it is possible to select an optimal base station with which a mobile station communicates by properly using three orthogonal PSCs between sectors in a cell controlled by the same base station. Proposals have been made.

  Further, in Non-Patent Document 3, propagation path estimation is performed from the difference between the received P-SCH signal waveform and the replica signal waveform held in the mobile station, and adjacent time regions are obtained using this propagation path estimation result. Compensation of the propagation path of the S-SCH transmitted in (1) is also described.

  FIG. 16 shows a radio frame proposed in Non-Patent Document 3. As shown in FIG. 16, a 10 ms frame is composed of 20 subframes of 0.5 ms. Each subframe is composed of seven OFDM symbols. The P-SCH is arranged in the last OFDM symbol of the first subframe and the eleventh subframe in one frame, and the S-SCH is arranged in the second OFDM symbol from the last.

  Next, FIG. 17 shows an example of a cell configuration. As shown in FIG. 17, cells a, b, and c are each composed of three sectors, and the above-mentioned frame is transmitted from base stations a, b, and c at the center of each cell to each sector in each cell. Structure radio waves are transmitted.

  Here, the code (SSC: Secondary Synchronization Code) assigned to the S-SCH is a signal unique to each cell, that is, the same SSC is transmitted to the S-SCH of each sector in the same cell. Shall be.

  In the cell shown in FIG. 17, it is assumed that the three orthogonal PSCs are used properly between sectors in the same cell as described above. The same PSC with the same sector number is used between different cells.

  The mobile station 1 performing the initial cell search receives signals transmitted from the sector 2 of the base station a, the sector 3 of the base station b, and the sector 1 of the base station c. Then, the correlation between the replicas held in the three types of P-SCHs and the received signal is observed for a certain period, and from the time when the correlation peak becomes maximum and the type of PSC, The sector number (here, sector 3) and the frame timing are acquired.

  Next, mobile station 1 performs channel estimation from the difference between the PSC replica of sector 3 and the received P-SCH signal. When the PSC of each sector is orthogonal, propagation path estimation can be performed in the orthogonal unit. Furthermore, the position of the S-SCH is identified from the acquired frame timing, and propagation path compensation is performed using the above-described P-SCH propagation path estimation result.

  Then, a scramble code group is identified from the S-SCH subjected to propagation path compensation, and a scramble code is identified from the C-RS. Here, although the scramble code is identified by the C-RS, it is also possible to construct a system for identifying the scramble code using the S-SCH.

  In the above, the case where three different PSCs are used has been described. When a plurality of different PSCs are used in this way, P-SCHs received from a plurality of cells (sectors) can be separated, and the channel estimation accuracy using these P-SCHs can be improved. it can. Thereby, propagation path compensation accuracy by S-SCH is improved, and propagation path compensation for each sector is possible, so that cell search performance (scramble code identification probability) can be improved.

On the other hand, when a common PSC is used in each sector, the P-SCH received from a plurality of cells (sectors) cannot be separated, so that the channel estimation accuracy using the P-SCH deteriorates. As a result, the S-SCH channel compensation accuracy is degraded, and the detection error of the scramble code is increased as compared with the case where a plurality of PSCs are used.
3GPP contributions “R1-0627222”, “Three-Step Cell Search Method for E-UTRA”, [November 1, 2006], Internet (URL: ftp://ftp.3gpp.org/TSG_RAN/WG1_RL1/TSG1_RL1/TSR1 Docs / R1-0662722.zip) 3GPP contributions “R1-070216,“ Further Results on Multiple P-SCH Complexity for E-UTRA Cell Search ”, [January 15, 2007 search], Internet (URL: ftp: //ftp.3gppp.Ng/TS /WG1_RL1/TSGR1_47bis/Docs/R1-070216.zip) 3GPP contribution “R1-070086”, “Investations on Primary-SCH sequences for E-UTRA Downlink”, [searched on January 15, 2007], Internet (URL: ftp: //ftp.3gpp.Org/TSG_R1/LG/RSG1/RG1/RSG1/RG TSGR1_47bis / Docs / R1-070086.zip)

  By the way, in E-UTRA, as described above, a cell search technique using a plurality of PSCs has been studied. However, in the mobile station at the sector end in the same cell as the mobile station 2 shown in FIG. 17, either the PSC replica of the sector 2 or the PSC of the sector 3 transmitted from the base station a (here, Propagation path estimation is performed using a replica of sector 2. For this reason, when identifying the scramble code group from the S-SCH, although the S-SCH of the other (sector 3) is the same SSC signal as the sector 2, it becomes an interference component and scramble code detection Performance will deteriorate. When a plurality of PSCs are used in this way, the scrambling code detection capability is improved at the cell end, but there is a problem that the detection capability is reduced at the sector end.

  On the other hand, when a single PSC is used, both S-SCH of sector 2 and S-SCH of sector 3 can be received as signal components. Scramble code detection capability is improved.

  The present invention has been made in view of such circumstances, and even when a plurality of PSCs are used, the overall cell search performance can be improved without reducing the scramble code detection capability at the sector end. It is an object of the present invention to provide a cell search method, a base station apparatus, and a mobile station apparatus.

  (1) In order to achieve the above object, the present invention has taken the following measures. That is, the cell search method according to the present invention is a cell search method in a radio communication system using a plurality of different PSCs as P-SCHs for each sector, and the plurality of PSCs are shared so that a part of each PSC is common. Setting, selecting either a common part of the plurality of PSCs or one of the PSCs, and performing propagation path estimation using the common part of the plurality of PSCs or any PSC. It is a feature.

  In this way, propagation path estimation is performed using a part or any of the PSCs common to the plurality of PSCs. For this reason, for example, when the mobile station apparatus exists at the sector end, the channel estimation is performed by using a part common to the plurality of PSCs, thereby performing the same as the channel estimation at the sector end with a single PSC. Characteristics can be obtained. As a result, it is possible to improve the overall cell search performance without degrading the scramble code detection capability at the sector end. When the mobile station apparatus exists at a position other than the sector end, the scramble code detection capability at the cell end or the like can be improved by performing propagation path estimation using any PSC.

  (2) In the cell search method according to the present invention, the position of the mobile station apparatus is estimated, and one of the common parts of the plurality of PSCs and one of the PSCs is selected according to the estimation result. It is characterized by that.

  In this way, a common part of a plurality of PSCs and any one of the PSCs are selected according to the estimation result of the position of the mobile station apparatus, and therefore, the propagation path depends on the position of the mobile station apparatus. The PSC used for estimation can be switched. For this reason, for example, when the mobile station apparatus exists at the sector end, the channel estimation is performed by using a part common to the plurality of PSCs, thereby performing the same as the channel estimation at the sector end with a single PSC. Characteristics can be obtained.

  (3) The cell search method according to the present invention is characterized in that the mobile station apparatus measures the received power of the received signal and estimates the position of the mobile station apparatus according to the magnitude of the received power. .

  Thus, since the position of the mobile station apparatus is estimated according to the magnitude of the received power, the PSC used for propagation path estimation can be switched according to the distance between the mobile station apparatus and the base station apparatus. For example, when the mobile station apparatus exists at the sector end, the same channel path estimation at a sector end with a single PSC is performed by performing channel estimation using a part common to a plurality of PSCs. Obtainable.

  (4) In the cell search method according to the present invention, the plurality of PSC replica signal waveforms are held in the mobile station apparatus, and the plurality of PSC received by the mobile station apparatus and the plurality of PSC replica signal waveforms The position of the mobile station apparatus is estimated according to the magnitude of the correlation value between

  Thus, since the position of the mobile station apparatus is estimated according to the magnitude of the correlation value between the received plurality of PSCs and the replica signal waveforms of the plurality of PSCs, the correlation between the plurality of PSCs is used. The PSC used for propagation path estimation can be switched. For example, when the mobile station apparatus exists at the sector end, the same channel path estimation at a sector end with a single PSC is performed by performing channel estimation using a part common to a plurality of PSCs. Obtainable.

  (5) In the cell search method according to the present invention, the plurality of PSC replica signal waveforms are held in the mobile station apparatus, and the plurality of PSC received by the mobile station apparatus, and the plurality of PSC replica signal waveforms The position of the mobile station apparatus is estimated according to the magnitude of the correlation value with the received time and the received time.

  As described above, since the position of the mobile station apparatus is estimated in accordance with the magnitude of the correlation value between the received plurality of PSCs and the replica signal waveforms of the plurality of PSCs and the received time, the correlation between the plurality of PSCs is estimated. The PSC used for propagation path estimation can be switched according to the relationship and the reception time of a plurality of PSCs. For example, when the mobile station apparatus exists at the sector end, the same channel path estimation at a sector end with a single PSC is performed by performing channel estimation using a part common to a plurality of PSCs. Obtainable.

  (6) In the cell search method according to the present invention, the PSC having the maximum correlation value among the plurality of PSCs is selected as one of the PSCs.

  As described above, since the PSC having the maximum correlation value among the plurality of PSCs is selected as one of the above PSCs, the scramble code detection capability can be improved even when performing propagation channel estimation using any one of the PSCs. It becomes possible to improve the cell search performance.

  (7) The base station apparatus of the present invention is a base station apparatus of a wireless communication system that uses a plurality of different PSCs as P-SCHs for each sector, and generates the plurality of PSCs having a common part in each PSC. A synchronization signal generation unit; and an output unit that outputs the plurality of PSCs generated by the synchronization signal generation unit for each sector.

  As described above, a plurality of PSCs having a common part in each PSC are generated and output for each sector. For example, when a mobile station device exists at the sector edge, a common part in the plurality of PSCs is obtained. By performing propagation path estimation using the same, it is possible to obtain the same characteristics as propagation path estimation at the sector edge with a single PSC. As a result, it is possible to improve the overall cell search performance without degrading the scramble code detection capability at the sector end.

  (8) The base station apparatus of the present invention is a base station apparatus of a radio communication system that uses a plurality of different PSCs as P-SCHs for each sector, and generates the plurality of PSCs having a common part in each PSC. A synchronization signal generation unit; and an output unit that outputs the plurality of PSCs generated by the synchronization signal generation unit for each sector. The synchronization signal generation unit includes S- Information that is a part of SCH and has high priority in cell search is arranged.

  As described above, a plurality of PSCs having a common part in each PSC are generated and output for each sector. For example, when a mobile station device exists at the sector edge, a common part in the plurality of PSCs is obtained. By performing propagation path estimation using the same, it is possible to obtain the same characteristics as propagation path estimation at the sector edge with a single PSC. Since information that is part of the S-SCH and has a high priority in cell search is arranged on subcarriers that share a common PSC, it is possible to enhance the demodulation system for information with a high priority. As a result, it is possible to improve the overall cell search performance without reducing the scramble code detection capability at the sector end.

  (9) The mobile station apparatus of the present invention is a mobile station apparatus of a wireless communication system that uses a plurality of different PSCs as P-SCHs for each sector, and the plurality of the plurality of PSCs set so as to share a part in each PSC. A receiving unit that receives the PSC, a PSC that maximizes a correlation value between the plurality of PSCs and the replica signal waveforms of the plurality of PSCs, and a reception power of the plurality of PSCs and a predetermined threshold value A synchronization unit that determines a subcarrier to be used for channel estimation by comparison and a channel estimation unit that performs channel estimation based on the subcarrier determined by the synchronization unit are provided.

  As described above, the PSC having the maximum correlation value between the plurality of PSCs and the replica signal waveforms of the plurality of PSCs is detected and used for propagation path estimation by comparing the received power of the plurality of PSCs with a predetermined threshold value. The subcarrier to be determined is determined. As a result, the PSC used for propagation path estimation can be switched according to the magnitude of the received power, so that the PSC used for propagation path estimation can be effectively selected according to the distance between the mobile station apparatus and the base station apparatus. Can do. For this reason, for example, when the mobile station apparatus exists at the sector end, the channel estimation is performed by using a part common to the plurality of PSCs, thereby performing the same as the channel estimation at the sector end with a single PSC. Characteristics can be obtained. As a result, it is possible to improve the overall cell search performance without degrading the scramble code detection capability at the sector end.

  (10) The mobile station apparatus of the present invention is a mobile station apparatus of a radio communication system that uses a plurality of different PSCs as P-SCH for each sector, and the plurality of the plurality of PSCs set so that a part of each PSC is common And detecting a maximum correlation value of each PSC from a correlation value between the plurality of PSCs and the replica signal waveforms of the plurality of PSCs, and a predetermined correlation value with the maximum correlation value of each PSC And a synchronization unit that determines a subcarrier to be used for channel estimation and a channel estimation unit that performs channel estimation based on the subcarrier determined by the synchronization unit.

  As described above, the maximum correlation value of each PSC is detected from the correlation values of the plurality of PSCs and the replica signal waveforms of the plurality of PSCs, and the propagation path is estimated by comparing the maximum correlation value of each PSC with a predetermined threshold value. The subcarriers to be used for are determined. As a result, the PSC used for propagation path estimation can be switched according to the correlation value between the plurality of PSCs and the replica signal waveforms of the plurality of PSCs. The PSC to be used can be selected. For this reason, for example, when the mobile station apparatus exists at the sector end, the channel estimation is performed by using a part common to the plurality of PSCs, thereby performing the same as the channel estimation at the sector end with a single PSC. Characteristics can be obtained. As a result, it is possible to improve the overall cell search performance without degrading the scramble code detection capability at the sector end.

  (11) The mobile station apparatus of the present invention is a mobile station apparatus of a wireless communication system using a plurality of different PSCs as P-SCHs for each sector, and the plurality of the plurality of PSCs set so as to share a part in each PSC. And detecting the maximum correlation value of each PSC and the detection timing of the maximum correlation value from the correlation values of the plurality of PSCs and the replica signal waveforms of the plurality of PSCs. A synchronization unit that determines a subcarrier to be used for channel estimation by comparing the maximum correlation value and the detection timing of the maximum correlation value with a predetermined threshold, and channel estimation based on the subcarrier determined by the synchronization unit And a propagation path estimation unit for performing the above.

  Thus, the maximum correlation value of each PSC and the detection timing of the maximum correlation value are detected from the correlation values of the plurality of PSCs and the replica signal waveforms of the plurality of PSCs, and the maximum correlation value and the maximum correlation of each PSC are detected. A subcarrier used for channel estimation is determined by comparing the value detection timing with a predetermined threshold. As a result, the PSC used for channel estimation can be switched according to the correlation value between the plurality of PSCs and the replica signal waveforms of the plurality of PSCs. A PSC used for propagation path estimation can be effectively selected according to the position. For this reason, for example, when the mobile station apparatus exists at the sector end, the channel estimation is performed by using a part common to the plurality of PSCs, thereby performing the same as the channel estimation at the sector end with a single PSC. Characteristics can be obtained. As a result, it is possible to improve the overall cell search performance without degrading the scramble code detection capability at the sector end.

  (12) The mobile station apparatus of the present invention is a mobile station apparatus of a wireless communication system using a plurality of different PSCs as P-SCH for each sector, and the plurality of the plurality of PSCs set so that a part of each PSC is common And a propagation path estimator that estimates a propagation path of a signal that is common in a sector using the PSCs of some of the common subcarriers.

  In this way, since the propagation path of the signal common to the sectors is estimated using the PSC of some common subcarriers, the demodulation system can be improved and the cell search performance can be improved. .

  (13) The mobile station apparatus of the present invention is a mobile station apparatus of a wireless communication system using a plurality of different PSCs as P-SCHs for each sector, and the plurality of the plurality of PSCs set so as to share a part in each PSC. Propagation for estimating the propagation path of subcarriers of information that is a part of S-SCH and has high priority in cell search, using a receiving unit that receives the PSC of the subcarrier and the PSCs of the common subcarriers A road estimation unit.

  In this way, using the plurality of PSCs set so that a part of each PSC is common, the subcarrier propagation path estimation of information that is a part of S-SCH and has a high priority in cell search is performed. Therefore, for example, by performing propagation path estimation using a part common to a plurality of PSCs when existing at the sector edge, characteristics similar to propagation path estimation at the sector edge with a single PSC are obtained. be able to. In addition, it is possible to enhance the demodulation system of information with high priority in cell search. As a result, it is possible to improve the overall cell search performance without reducing the scramble code detection capability at the sector end.

  According to the present invention, propagation path estimation is performed using a common part or any one of a plurality of PSCs among a plurality of PSCs set so that a part of each PSC is common. From the above, for example, when the mobile station apparatus exists at the sector end, the channel estimation is performed by using a part common to the plurality of PSCs, and thus the same as the channel estimation at the sector end with a single PSC. Characteristics can be obtained. As a result, even when a plurality of PSCs are used, it is possible to improve the overall cell search performance without reducing the scramble code detection capability at the sector end.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
First, P-SCH used in the cell search method according to the present invention will be described below. The P-SCH in the present invention uses a plurality of PSCs, and those designed so that the signals of some subcarriers of each PSC arranged on the frequency axis are the same.

FIG. 1 is a diagram illustrating an example of P-SCHs arranged on subcarriers on the frequency axis used in the cell search method according to the first embodiment of the present invention. As shown in FIG. 1, a P-SCH code (PSC (1, n)) for sector 1, a P-SCH code (PSC (2, n)) for sector 2, and a P-SCH code (PSC (3) for sector 3 , N)) is expressed by the following equation.
PSC (1, n) = A (n) * exp (j * 2 * pi * 0/3 * n)
PSC (2, n) = A (n) * exp (j * 2 * pi * 2/3 * n)
PSC (3, n) = A (n) * exp (j * 2 * pi * 4/3 * n)
n = 0, 1, 2,..., N-1 (N is the code length used in P-SCH)

If A (n) = 1 (n = 0, 1,..., 12-1), PSC (1), PSC (2), and PSC (3) are expressed as follows according to FIG. From exp (j * 0) = 1, the same signal (= 1) appears in three PSCs at intervals of 4 subcarriers. This is also true when A (n) takes an arbitrary value.
PSC (1) = [1 1 1 1 1 1 1 1 1 1 1 1]
PSC (2) = exp (j * [0 2π / 3 4π / 3 0 2π / 3 4π / 3 0 2π / 3 4π / 3 0 2π / 3 4π / 3])
PSC (3) = exp (j * [0 4π / 3 2π / 3 0 4π / 3 2π / 3 0 4π / 3 2π / 3 0 4π / 3 2π / 3])

  Here, an example of a base station apparatus (hereinafter referred to as “base station” where appropriate) that transmits the above three types of PSCs as P-SCH of each sector is shown. FIG. 2 is a block diagram illustrating a configuration of the base station according to the first embodiment.

  As shown in FIG. 2, the base station 100 according to the first embodiment includes a control unit 101 that controls each circuit block, a reception antenna unit 102, a reception analog circuit unit 103, an A / D conversion unit 104, and A demodulation processing unit 105 is provided. The base station 100 includes a data modulation unit 106, a control signal modulation unit 107, a synchronization signal generation unit 108, a multiplexing / modulation processing unit 109, a D / A conversion unit 110, a transmission analog circuit unit 111, and a transmission antenna unit 112. ing.

  The receiving antenna unit 102 receives radio waves from each mobile station in each of the three sectors. The reception analog circuit unit 103 converts the received signal into a frequency that can be demodulated. The A / D conversion unit 104 converts the analog signal processed by the reception analog circuit unit 103 into a digital signal. The demodulation processing unit 105 demodulates the digital signal converted by the A / D conversion unit 104.

  The data modulation unit 106 modulates transmission data to a mobile station apparatus (hereinafter referred to as “mobile station”) 200 described later. The control signal modulation unit 107 modulates a control signal to the mobile station 200. The synchronization signal generation unit 108 generates the synchronization signal (P-SCH, S-SCH). The multiplexing / modulation processing unit 109 performs multiplexing / modulation processing using the synchronization signal, the control signal, and the data signal as transmission frames. The D / A converter 110 converts the modulated signal into an analog signal. The transmission analog circuit unit 111 converts the D / A converted analog signal into a frequency necessary for transmission. The transmission antenna unit 112 is an antenna for transmitting to each mobile station 200.

  Base station 100 has such a configuration, and PSC (1), PSC (2), and PSC (3) described above are assigned by synchronization signal generation section 108 for each sector. This makes it possible to generate and transmit P-SCH in which the same signal appears in three PSCs at a constant subcarrier interval.

  The mobile station 200 near the sector edge in the same cell performs propagation path estimation using only the PSC of the subcarrier to which the same signal is transmitted by the above-described PSC, so that the mobile station 200 at the sector edge in the single PSC It is possible to obtain the same characteristics as the propagation path estimation.

  When performing such propagation path estimation, the mobile station 200 must appropriately grasp the position of the own station in the cell. For this reason, the mobile station 200 according to the present invention estimates the position of the local station and selects a subcarrier to be used for channel estimation. Hereinafter, an example of the mobile station 200 according to the first embodiment is shown. FIG. 3 is a block diagram showing the configuration of the mobile station according to the first embodiment.

  As shown in FIG. 3, the mobile station 200 according to the first embodiment includes a reception antenna unit 201, a reception analog circuit unit 202, an A / D conversion unit 203, a synchronization unit 204, a GI removal unit 205, and an S / P conversion. Unit 206, FFT unit 207, propagation path estimation unit 208, and demodulation unit 209. In addition, the mobile station 200 includes a modulation unit 210, an IFFT unit 211, a P / S conversion unit 212, a GI addition unit 213, a D / A conversion unit 214, a transmission analog circuit unit 215, a transmission antenna unit 216, and a control unit 217. ing.

  The receiving antenna unit 201 receives a signal transmitted from the base station 100. The reception analog circuit unit 202 converts the received analog signal into a signal having a frequency that can be demodulated. The A / D converter 203 converts the analog signal processed by the reception analog circuit unit 202 into a digital signal. The synchronization unit 204 performs synchronization with the base station 100 based on the received digital signal. The GI removal unit 205 removes the guard interval (GI) at the synchronized timing. The S / P converter 206 converts the serial signal from which the GI has been removed into a parallel signal. The FFT unit 207 performs FFT on the time domain signal converted into the parallel signal to convert it into a frequency domain signal. Based on the control signal from control section 217, propagation path estimation section 208 selects only the signal used for propagation path estimation from the signal converted into the frequency domain, and performs propagation path estimation. The demodulator 209 demodulates the signal converted into the frequency domain.

  Modulation section 210 modulates transmission data from mobile station 200. The IFFT unit 211 converts the modulated frequency domain signal into a time domain signal. The P / S converter 212 converts the time domain parallel signal converted by the IFFT unit 211 into a serial signal. The GI adding unit 213 adds a GI to the P / S converted signal. The D / A converter 214 converts the digital signal to which the GI is added into an analog signal. The transmission analog circuit unit 215 converts the D / A converted analog signal into a frequency necessary for transmission. The transmission antenna unit 216 is an antenna for transmitting to the base station 100. The control unit 217 controls the operation of each circuit.

  Here, the configuration of the synchronization unit 204 included in the mobile station 200 according to the first embodiment will be described. FIG. 4 is a block diagram illustrating a configuration of the synchronization unit 204 included in the mobile station 200 according to the first embodiment.

  As illustrated in FIG. 4, the synchronization unit 204 includes first to third correlators 301 to 303, first to third buffers 304 to 306, a maximum value detector 307, and a received power measurement unit 308. Use subcarrier setting section 309.

  First to third correlators 301 to 303 correlate three types of PSC replicas held in advance with received signals. The first to third buffers 304 to 306 hold the correlation results (correlation values) of the first to third correlators 301 to 303, respectively, for a certain period. The maximum value detector 307 acquires the type of the PSC that takes the maximum value, the maximum timing, and the maximum value from the correlation values held in the first to third buffers 304 to 306. Received power measuring section 308 measures the power of the received signal. The used subcarrier setting unit 309 compares the received power measured by the received power measuring unit 308 with a threshold value, and outputs subcarrier information used for channel estimation (channel estimation usage subcarrier information).

  Note that the synchronization unit 204 determines that the received power is larger as the propagation path estimation utilization subcarrier information, that it is closer to the base station 100. If the received power is equal to or greater than the threshold, the P-SCH of another cell is not received. Therefore, a signal using only the PSC of the subcarrier to which the same signal is transmitted by the three PSCs described above is output. In contrast, if the received power is smaller, it is determined that the received power is farther from the base station. If the received power is less than the threshold, it is considered that the P-SCH of another cell is also received, and the PSC having the maximum correlation value in the PSC described above A signal using is output.

  As described above, according to the cell search method according to the first embodiment, by using the mobile station 200 including the synchronization unit 204 having the above-described configuration, the same PPS can be used in three PSCs according to the position of the mobile station 200. It is possible to select a PSC of a subcarrier to which a signal is transmitted or a PSC having a maximum correlation value, and appropriately select a P-SCH subcarrier used for S-SCH channel estimation. As a result, the cell search performance can be improved.

  In particular, in the cell search method according to the first embodiment, propagation path estimation is performed using PSCs of subcarriers in which the same signal is transmitted by three PSCs, which corresponds to a part common to a plurality of PSCs. Therefore, the same characteristics as the propagation path estimation at the sector edge with a single PSC can be obtained. As a result, it is possible to improve the overall cell search performance without degrading the scramble code detection capability at the sector end.

  In the cell search method according to the first embodiment, since the position of the mobile station 200 is estimated according to the magnitude of received power, the propagation path is estimated according to the distance between the mobile station 200 and the base station 100. The PSC used for the can be switched.

  Note that threshold values input to the used subcarrier setting unit 309 shown in FIG. 4 include, for example, i) a value determined in advance by system specifications, ii) a fixed value determined in advance by the mobile station 200, and iii) movement. Various values such as a value calculated based on the number of cell search failures at the station 200 can be used.

(Second Embodiment)
In the cell search method according to the first embodiment, a case is described in which received power is used for calculation of propagation path estimation utilization subcarrier information. On the other hand, the cell search method according to the second embodiment is different from the cell search method according to the first embodiment in that another method is used for calculation of propagation path estimation utilization subcarrier information.

  Note that the cell search method according to the second embodiment is different from the cell search method according to the first embodiment only in the synchronization unit 204 provided in the mobile station 200. Since the configurations of the base station 100 and the mobile station 200 are the same as those of the cell search method according to the first embodiment, the description thereof is omitted.

  FIG. 5 is a block diagram illustrating a configuration of the synchronization unit 204 included in the mobile station 200 according to the second embodiment. 5 that have the same reference numerals as those in FIG. 4 have the same functions, and a description thereof will be omitted. As shown in FIG. 5, the synchronization unit 204 according to the second embodiment includes the first to third maximum value detectors 401 to 403, a comparison unit 404, and a used subcarrier setting unit 405. This is different from the synchronization unit 204 according to the embodiment.

  The first to third maximum value detectors 401 to 403 obtain respective maximum timings and respective maximum values from the correlation values held in the first to third buffers 304 to 306. The comparison unit 404 selects the maximum PSC type from the correlation values acquired by the first to third maximum value detectors 401 to 403 and outputs it as the sector determination result, while the maximum timing is set to the time. Output as synchronization timing. The used subcarrier setting unit 405 outputs channel estimation utilization subcarrier information using the input parameters and the maximum values of the correlation values acquired by the first to third maximum value detectors 401 to 403. .

  As described in the cell search method according to the first embodiment, in a plurality of PSCs, performing channel estimation using only PSC signals of subcarriers to which the same signal is transmitted exists near the sector edge. This is effective for the mobile station 200 to be operated. For this reason, in the cell search method according to the second embodiment, the used subcarrier setting unit 405 determines the input parameters and the correlation values acquired by the first to third maximum value detectors 401 to 403. Using the maximum value, it is determined whether or not the mobile station 200 is at the sector end, and propagation path estimation utilization subcarrier information corresponding to the determination result is output. The configuration and operation of the used subcarrier setting unit 405 according to the second embodiment will be described below. Here, two aspects will be described.

  In the used subcarrier setting section 405 (hereinafter referred to as “first used subcarrier setting section 405”) of the first aspect, a threshold value is input as a parameter. The first used subcarrier setting unit 405 compares this threshold value with each correlation value acquired by the first to third maximum value detectors 401 to 403. If there are two values that are equal to or greater than the threshold, a signal using only the PSC signal of the subcarrier in which the same signal is transmitted using three PSCs is output as the propagation path estimation utilization subcarrier information. On the other hand, if there are other than two values that are equal to or greater than the threshold, a signal using the PSC with the maximum correlation value is output as the propagation channel estimation utilization subcarrier information.

  That is, when two types of PSCs with high power are observed, it is determined that the mobile station 200 is not at the cell edge but at the sector edge, but otherwise, the mobile station 200 is at the sector center or cell edge. Determine that you are in In the former case, since propagation path estimation is performed using PSCs of subcarriers in which the same signal is transmitted with three PSCs, characteristics similar to those of propagation path estimation at the sector end with a single PSC. Can be obtained. As a result, it is possible to improve the overall cell search performance without degrading the scramble code detection capability at the sector end.

  The operation of the first used subcarrier setting unit 405 will be described with reference to FIG. FIG. 6 is a flowchart for explaining the operation of the first used subcarrier setting unit 405 according to the second embodiment.

  As shown in FIG. 6, first used subcarrier setting section 405 first resets variable Th to 0 (step (hereinafter referred to as “ST”) 11), and proceeds to ST12. In ST12, the correlation value 1 acquired from the first maximum value detector 401 is compared with the threshold value. As a result of the comparison, if the correlation value 1 is greater than or equal to the threshold, the process proceeds to ST13, and if it is less than the threshold, the process proceeds to ST14. In ST13, 1 is added to the value of the variable Th, and the process proceeds to ST14.

  In ST14, the correlation value 2 acquired from the second maximum value detector 402 is compared with the threshold value. If the correlation value 2 is greater than or equal to the threshold value as a result of comparison, the process proceeds to ST15, and if it is less than the threshold value, the process proceeds to ST16. In ST15, 1 is added to the value of the variable Th, and the process proceeds to ST16. In ST16, the correlation value 3 acquired from the third maximum value detector 403 is compared with the threshold value. As a result of the comparison, if the correlation value 3 is greater than or equal to the threshold, the process proceeds to ST17, and if it is less than the threshold, the process proceeds to ST18. In ST17, 1 is added to the value of the variable Th, and the process proceeds to ST18.

  In ST18, it is determined whether or not the value of the variable Th is 2. As a result of this determination, if the value of the variable Th is 2, the process proceeds to ST19, and if other than 2, the process proceeds to ST20. In ST19, a signal using only the PSC of the subcarrier in which the same signal is transmitted using three PSCs is output to control section 217 as the propagation path estimation utilization subcarrier information. On the other hand, in ST20, a signal using the PSC having the maximum correlation value is output to the control unit as the propagation path estimation utilization subcarrier information. By such an operation, it is possible to determine whether or not the mobile station 200 is at the sector edge, and to output the channel estimation utilization subcarrier information according to the determination result to the control unit 217.

  On the other hand, in use subcarrier setting section 405 (hereinafter referred to as “second use subcarrier setting section 405”) of the second mode, threshold 1 and threshold 2 are input as parameters. The second used subcarrier setting unit 405 compares the magnitudes of the correlation values (correlation value 1, correlation value 2, correlation value 3) acquired by the first to third maximum value detectors 401 to 403. Then, the absolute value (Da) of the difference between the maximum value and the second largest value and the absolute value (Db) of the difference between the second largest value and the minimum value are calculated. Then, these absolute values (Da, Db) are compared with the threshold values (threshold value 1 and threshold value 2). If Da is less than threshold value 1 and Db is greater than or equal to threshold value 2, a signal using only PSCs of subcarriers where the same signal is transmitted using three PSCs is output as propagation path estimation utilization subcarrier information. On the other hand, otherwise, a signal using the PSC having the maximum correlation value is output as the propagation path estimation utilization subcarrier information.

  That is, when two types of PSCs are observed at the same power level and the remaining types of PSCs are observed at a low power level, the mobile station 200 is determined to be at the sector end. It is determined that the mobile station 200 is at the sector center or the cell edge. In the former case, since propagation path estimation is performed using PSCs of subcarriers in which the same signal is transmitted with three PSCs, characteristics similar to those of propagation path estimation at the sector end with a single PSC. Can be obtained. As a result, it is possible to improve the overall cell search performance without degrading the scramble code detection capability at the sector end.

  The operation of the second used subcarrier setting unit 405 will be described with reference to FIG. FIG. 7 is a flowchart for explaining the operation of the second used subcarrier setting unit 405 according to the second embodiment.

  As illustrated in FIG. 7, the second used subcarrier setting unit 405 first acquires the correlation value 1 acquired from the first maximum value detector 401 and the second maximum value detector 402 in ST21. The correlation value 2 is compared with the correlation value 3 acquired from the third maximum value detector 403, the maximum value is A, the second largest value is B, and the minimum value is C, and the process proceeds to ST22. In ST22, Da = A−B and Db = B−C are calculated, and the process proceeds to ST23.

  In ST23, Da is compared with threshold value 1. As a result of the comparison, if Da is less than the threshold value 1, the process proceeds to ST24, and if it is equal to or greater than the threshold value 1, the process proceeds to ST26. In ST24, Db is compared with threshold value 2. If Db is greater than or equal to the threshold value 2 as a result of the comparison, the process proceeds to ST25, and if it is less than the threshold value 2, the process proceeds to ST26.

  In ST25, a signal using only the PSC of the subcarrier in which the same signal is transmitted using three PSCs is output to control section 217 as the propagation path estimation utilization subcarrier information. On the other hand, in ST26, a signal using the PSC having the maximum correlation value is output to control section 217 as the propagation path estimation utilization subcarrier information. By such an operation, it is possible to determine whether or not the mobile station 200 is at the sector edge, and to output the channel estimation utilization subcarrier information according to the determination result to the control unit 217.

  In ST24, the difference between the correlation values is compared with the threshold value 2, but it is also possible to make a determination by comparing the minimum correlation value with the threshold value 2. In this case, the maximum correlation value should also be compared with another threshold 3 (threshold 3> threshold 2) to determine whether the difference from the minimum correlation value is sufficiently large. .

(Third embodiment)
In the cell search method according to the second embodiment, only the maximum value of each correlation value acquired by the first to third maximum value detectors 401 to 403 is used for calculation of propagation path estimation utilization subcarrier information. It explains about. On the other hand, in the cell search method according to the third embodiment, the maximum value of each correlation value acquired by the first to third maximum value detectors 401 to 403 is used to calculate the propagation path estimation utilization subcarrier information. In addition, it differs from the cell search method according to the second embodiment in that each maximum timing is used.

  Note that the cell search method according to the third embodiment is different from the cell search method according to the second embodiment only in the synchronization unit 204 provided in the mobile station 200. The configurations of the base station 100 and the mobile station 200 are the same as those of the cell search method according to the second embodiment, and thus description thereof is omitted.

  FIG. 8 is a block diagram illustrating a configuration of the synchronization unit 204 included in the mobile station 200 according to the third embodiment. In addition, in FIG. 8, about the structure which attached | subjected the code | symbol same as FIG. 5, it shall have the same function and the description is abbreviate | omitted. As illustrated in FIG. 8, the synchronization unit 204 according to the third embodiment is different from the synchronization unit 204 according to the second embodiment in that a use subcarrier setting unit 501 is provided.

  The used subcarrier setting unit 501 uses the input parameters, the maximum values of the correlation values acquired by the first to third maximum value detectors 401 to 403, and the propagation path estimation using the maximum timing. Use subcarrier information is output. That is, it differs from the used subcarrier setting unit 405 according to the second embodiment in that the propagation path estimation using subcarrier information is output using not only the maximum value of each correlation value but also the maximum timing.

  The used subcarrier setting unit 501 uses the input parameters, the maximum values of the correlation values acquired by the first to third maximum value detectors 401 to 403, and the timings at which the maximum values are obtained. Is at the edge of the sector, and propagation path estimation utilization subcarrier information corresponding to the determination result is output. Hereinafter, the configuration and operation of the used subcarrier setting unit 501 according to the third embodiment will be described. Here, two aspects will be described.

  In used subcarrier setting section 501 (hereinafter referred to as “first used subcarrier setting section 501”) of the first aspect, threshold value P and threshold value t are input as parameters. Of these, the first used subcarrier setting unit 501 compares the threshold value P with each correlation value acquired by the first to third maximum value detectors 401 to 403. If there are two values greater than or equal to the threshold value P and the difference between the two maximum timings is less than or equal to the threshold value t, the same signal is transmitted by three PSCs as propagation path estimation subcarrier information. A signal using only the subcarrier PSC signal is output. On the other hand, otherwise, a signal using the PSC having the maximum correlation value is output as the propagation path estimation utilization subcarrier information.

  That is, when two types of PSCs with strong power (greater than or equal to the threshold value P) are observed at approximately the same time (within the threshold value t), the mobile station 200 determines that the mobile station 200 is not at the cell edge but at the sector edge, Otherwise, it is determined that the mobile station 200 is at the sector center or cell edge. In the former case, since propagation path estimation is performed using PSCs of subcarriers in which the same signal is transmitted with three PSCs, characteristics similar to those of propagation path estimation at the sector end with a single PSC. Can be obtained. As a result, it is possible to improve the overall cell search performance without degrading the scramble code detection capability at the sector end.

  The operation of the first used subcarrier setting unit 501 will be described with reference to FIG. FIG. 9 is a flowchart for explaining the operation of the first used subcarrier setting unit 501 according to the third embodiment.

  As shown in FIG. 9, first used subcarrier setting section 501 first acquires correlation value 1 acquired from first maximum value detector 401 and second maximum value detector 402 in ST31. The correlation value 2 is compared with the correlation value 3 acquired from the third maximum value detector 403, the maximum value is A, the timing is At, the second largest value is B, the timing is Bt, and the minimum value is Go to ST32 and go to ST32.

  In ST32, A and the threshold value P are compared. As a result of the comparison, if A is greater than or equal to the threshold P, the process proceeds to ST33, and if it is less than the threshold P, the process proceeds to ST37. In ST33, B and threshold P are compared. If B is greater than or equal to the threshold P as a result of the comparison, the process proceeds to ST34, and if B is less than the threshold P, the process proceeds to ST37. Further, in ST34, C and threshold value P are compared. If C is less than the threshold value P as a result of the comparison, the process proceeds to ST35, and if it is equal to or greater than the threshold value P, the process proceeds to ST37.

  In ST35, the difference between At and Bt (the absolute value of At-Bt) is compared with the threshold value t. As a result of the comparison, if the difference between At and Bt is less than the threshold t, the process proceeds to ST36, and if the difference is greater than or equal to the threshold t, the process proceeds to ST37.

  In ST36, a signal using only the PSC of the subcarrier in which the same signal is transmitted using three PSCs is output to control section 217 as the propagation path estimation utilization subcarrier information. On the other hand, in ST37, a signal using the PSC having the maximum correlation value is output to control section 217 as the propagation path estimation utilization subcarrier information. By such an operation, it is possible to determine whether or not the mobile station 200 is at the sector edge, and to output the channel estimation utilization subcarrier information according to the determination result to the control unit 217.

  On the other hand, in the used subcarrier setting section 501 (hereinafter referred to as “second used subcarrier setting section 501”) of the second mode, threshold 1 and threshold 2 and threshold t are input as parameters. The second used subcarrier setting unit 501 compares the magnitudes of the correlation values (correlation value 1, correlation value 2, and correlation value 3) acquired by the first to third maximum value detectors 401 to 403. Then, the absolute value (Da) of the difference between the maximum value and the second largest value and the absolute value (Db) of the difference between the second largest value and the minimum value are calculated.

  If Da is less than threshold value 1 and Db is greater than or equal to threshold value 2 and the difference in correlation timing that takes the second largest value from the maximum value is less than or equal to threshold value t, the channel estimation utilization subcarrier information is 3 A signal using only the PSC of the subcarrier in which the same signal is transmitted by one PSC is output. On the other hand, otherwise, a signal using the PSC having the maximum correlation value is output as the propagation path estimation utilization subcarrier information.

  That is, when two types of PSCs are observed at approximately the same time with the same power level and the remaining types of PSCs are observed at low power levels, it is determined that the mobile station 200 is at the sector end, Otherwise, it is determined that the mobile station 200 is at the sector center or cell edge. In the former case, since propagation path estimation is performed using PSCs of subcarriers in which the same signal is transmitted with three PSCs, characteristics similar to those of propagation path estimation at the sector end with a single PSC. Can be obtained. As a result, it is possible to improve the overall cell search performance without degrading the scramble code detection capability at the sector end.

  The operation of the second used subcarrier setting unit 501 will be described with reference to FIG. FIG. 10 is a flowchart for explaining the operation of the second used subcarrier setting unit 501 according to the third embodiment.

  As shown in FIG. 10, the second used subcarrier setting section 501 first acquires the correlation value 1 acquired from the first maximum value detector 401 and the second maximum value detector 402 in ST41. The correlation value 2 is compared with the correlation value 3 acquired from the third maximum value detector 403, the maximum value is A, the second largest value is B, and the minimum value is C, and the process proceeds to ST42. In ST42, Da = A−B and Db = B−C are calculated, and the process proceeds to ST43.

  In ST43, Da is compared with threshold value 1. As a result of the comparison, if Da is less than threshold value 1, the process proceeds to ST44, and if it is greater than or equal to threshold value 1, the process proceeds to ST47. In ST44, Db is compared with threshold value 2. As a result of the comparison, if Db is greater than or equal to the threshold value 2, the process proceeds to ST45, and if it is less than the threshold value 2, the process proceeds to ST47. In ST45, the difference between At and Bt (the absolute value of At-Bt) is compared with the threshold value t. As a result of the comparison, if the difference between At and Bt is less than the threshold value t, the process proceeds to ST46, and if the difference is greater than or equal to the threshold value t, the process proceeds to ST47.

  In ST46, a signal using only the PSC of the subcarrier in which the same signal is transmitted using three PSCs is output to control section 217 as the propagation path estimation utilization subcarrier information. On the other hand, in ST47, a signal using the PSC having the maximum correlation value is output to the control section 217 as the propagation path estimation utilization subcarrier information. With such an operation, it is possible to determine whether or not the mobile station 200 is at the sector edge, and to output the channel estimation utilization subcarrier information according to the determination result to the control unit 217.

  In ST44, as in ST24 in the second embodiment, the difference between the correlation values is compared with the threshold 2. However, it is also possible to make a determination by comparing the minimum correlation value with the threshold 2. is there. In this case, the maximum correlation value should also be compared with another threshold 3 (threshold 3> threshold 2) to determine whether the difference from the minimum correlation value is sufficiently large. .

(Fourth embodiment)
In the cell search methods according to the first to third embodiments, a case has been described in which three orthogonal PSCs are generated by changing the phase of one sequence. On the other hand, the cell search method according to the fourth embodiment is different from the first to third embodiments in that three types of PSCs are generated by frequency multiplexing PSCc and PSCd, which will be described later. This is different from the cell search method. In the cell search method according to the fourth embodiment, the base station 100 and the mobile station 200 according to the first to third embodiments can be used.

  FIG. 11 shows an example of P-SCH used in the cell search method according to the fourth embodiment. As shown in FIG. 11, the P-SCH code (PSC (1)) for sector 1, the P-SCH code (PSC (2)) for sector 2, and the P-SCH code (PSC (3)) for sector 3 are It consists of PSCc, PSCd (1), PSCd (2), and PSCd (3).

  Here, PSCd (1), PSCd (2), and PSCd (3) are orthogonal to each other. The PSCc and each PSCd may or may not be orthogonal, but the signals in the time domain of the PSC (1), PSC (2), and PSC (3) configured in combination are synchronized. Therefore, it is desirable that the cross-correlation value is low.

  In this way, the PSC is set, and the propagation path estimation unit 208 of the mobile station 200 performs propagation path estimation using only PSCd at the cell edge, while only PSCc or both PSCc and PSCd are near the cell center. By performing propagation path estimation using, it is possible to obtain the same effects as those of the cell search methods according to the first to third embodiments.

(Fifth embodiment)
In the cell search method according to the fourth embodiment, a case has been described in which three types of PSCs are generated by frequency-multiplexing PSCc and PSCd. In contrast, the cell search method according to the fifth embodiment is different from the cell search method according to the fourth embodiment in that three types of PSCs are generated by time-multiplexing PSCc and PSCd. In the cell search method according to the fifth embodiment, the base station 100 and the mobile station 200 according to the first to third embodiments are similar to the cell search method according to the fourth embodiment. Can be used.

  FIG. 12 is a diagram for explaining a radio frame in the cell search method according to the fifth embodiment. As shown in FIG. 12, the radio frame (10 ms) in the cell search method according to the fifth embodiment is composed of 20 subframes of 0.5 ms. Each subframe is composed of seven OFDM symbols. The P-SCH according to the fifth embodiment is configured using two OFDM symbols, and a PSCc common between sectors is arranged in the OFDM symbol of the first P-SCH, and the second P-SCH is used. In the SCH OFDM symbol, orthogonal PSCd is arranged between sectors. 12A shows the case where two P-SCHs are arranged in one subframe, and in FIG. 12B, two P-SCHs are arranged in one frame. Shows when to do.

  FIG. 13 shows an example of P-SCH used in the cell search method according to the fifth embodiment. As shown in FIG. 13, the P-SCH code (PSC (1)) for sector 1, the P-SCH code (PSC (2)) for sector 2, and the P-SCH code (PSC (3)) for sector 3 are It is composed of PSCc arranged in the first OFDM symbol and PSCd (1), PSCd (2) and PSCd (3) arranged in the second OFDM symbol.

  Here, PSCd (1), PSCd (2), and PSCd (3) are orthogonal to each other. PSCc and each PSCd may or may not be orthogonal.

  While the PSC is set in this way, the propagation path estimation unit 208 of the mobile station 200 performs propagation path estimation using only PSCd at the cell edge, as in the cell search method according to the fourth embodiment. By performing propagation path estimation using only PSCc or both PSCc and PSCd in the vicinity of the cell center, the same effects as those of the cell search methods according to the first to third embodiments can be obtained. .

(Sixth embodiment)
In the fourth embodiment, the method for selecting whether to use only the PSC of the subcarrier in which the same signal is transmitted with three PSCs or the PSC with the maximum correlation value has been described for channel estimation. . In the present embodiment, information having a high priority in cell search (for example, micro cell division information such as a normal macro cell / hot spot of the cell, S-SCH, etc.) for subcarriers to which the same signal is transmitted by three PSCs. A method for improving the cell search performance by arranging a part of the S-SCH having the scrambling code information (such as information on the scrambled code) in FIG. Since the configurations of the base station 100 and the mobile station 200 used in the present embodiment are the same as those in the cell search method according to the fourth embodiment, description thereof is omitted.

  FIG. 14 is a diagram illustrating an example of arrangement of P-SCH and S-SCH on the frequency axis in the present embodiment. In FIG. 14, the arrangement shown in FIG. 16 is used on the time axis. Similar to the fourth embodiment, the P-SCH used in the present embodiment on the frequency axis is such that PSCc, which is a code common to the sectors, is arranged on the subcarriers at regular intervals. Next, the S-SCH code is composed of a plurality of codes shorter than the entire length of the S-SCH code. Here, as shown in FIG. 14, it is assumed that an S-SCH code having a length of 11 is composed of two codes (length 3 of s1 and length 9 of s2). s1 is arranged on the same subcarrier as the subcarrier on which PSCc of P-SCH is arranged. S2 is arranged on other subcarriers.

  The propagation path estimation unit in the present embodiment of the mobile station 200 performs propagation path estimation using only PSCd at the cell edge, while performing propagation path estimation using only PSCc or both PSCc and PSCd near the cell center. By performing, the same effect as the cell search method according to the first to third embodiments can be obtained.

  Here, regarding the propagation path compensation of s1 in the vicinity of the cell center, as shown in FIG. 15, the received signal c ′ of PSCc on the same subcarrier and the code c held by the mobile station for each subcarrier. Compensation processing is performed by performing propagation path estimation from the amplitude / phase difference and performing compensation for each subcarrier on the received s1 ′ using the propagation path estimation value (s1 = s1 ′ × c / c ′). It is possible to perform accurate compensation without using the above. That is, by arranging a part of the S-SCH having high priority information (here, s1) in the subcarriers where the same signal is transmitted by the three PSCs, the demodulation accuracy of s1 can be improved. Search performance can be improved.

  If the high priority information is a macro cell / micro cell classification, it is possible to move to the next cell search if the mobile station is not the cell desired by the mobile station before obtaining the information from the code of s2. . If the high priority information is scrambling code information multiplied by s2, the information is obtained from s2 by removing the scramble of s2 after obtaining the scrambling code information from s1. Can do.

  In the present embodiment, s1 is arranged on the same subcarrier as the PSCc subcarrier, but can be arranged on an adjacent subcarrier as long as a reduction in propagation path compensation accuracy can be allowed. Moreover, although the P-SCH code in the fourth embodiment is used in the present embodiment, the same effect can be obtained even if the P-SCH code in the first to third embodiments is used. Further, in the first to sixth embodiments, in order to perform propagation path compensation of S-SCH, which is a signal common to sectors, propagation using PSC of subcarriers in which the same signal is transmitted by three PSCs. Although path estimation is performed, the PSC can be used for propagation path compensation of another signal common to sectors (for example, a broadcast channel that broadcasts to the entire cell).

  In the cell search methods according to the first to sixth embodiments, propagation path estimation is performed using only PSCs of subcarriers where the same signal is transmitted using three PSCs, or correlation values are used. Shows only using the largest PSC. In this case, there are two types of methods using the PSC having the maximum correlation value.

  The first method is to grasp the deviation in the frequency domain between the received P-SCH signal and the PSC as it is. This method is suitable for channel estimation near the center of the cell where no other PSC is received. The second method uses the orthogonality of the PSC, and makes use of the fact that each PSC can be separated in units that are orthogonal, and the frequency domain between the received P-SCH signal and the PSC. It is intended to grasp the deviation in the orthogonal unit. This method is suitable for channel estimation in the vicinity of the cell edge where the PSC of another cell is received.

  Therefore, in the cell search method according to the first embodiment, it is conceivable to always perform channel estimation using the second method if the received power is less than a threshold value. Further, in the cell search methods according to the second to sixth embodiments, when performing using the PSC having the maximum correlation value, if the maximum correlation value is equal to or greater than a certain threshold, It is considered that channel estimation is performed using the first method, and channel estimation using the second method is performed if it is less than the threshold value.

  The present invention is not limited to the embodiment described above, and can be implemented with various modifications. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the cell search methods according to the first to sixth embodiments, the case where three types of PSC are used is described, but the type of PSC is not limited to this, Changes can be made as appropriate. Even if there are a plurality of types other than the three types, in the cell search method according to the first embodiment, the cell search methods according to the second to sixth embodiments have “the top two types with large correlation”. This can be realized by measuring the power difference and the timing difference for the “other” PSC.

It is a figure which shows an example of P-SCH used with the cell search method which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structure of the base station which concerns on 1st Embodiment. It is a block diagram which shows the structure of the mobile station which concerns on 1st Embodiment. It is a block diagram which shows the structure of the synchronizer with which the mobile station which concerns on 1st Embodiment is provided. It is a block diagram which shows the structure of the synchronizer with which the mobile station which concerns on the 2nd Embodiment of this invention is provided. It is a flowchart for demonstrating operation | movement of the 1st use subcarrier setting part which concerns on 2nd Embodiment. It is a flowchart for demonstrating operation | movement of the 2nd use subcarrier setting part which concerns on 2nd Embodiment. It is a block diagram which shows the structure of the synchronizer with which the mobile station which concerns on the 3rd Embodiment of this invention is provided. It is a flowchart for demonstrating operation | movement of the 1st use subcarrier setting part which concerns on 3rd Embodiment. It is a flowchart for demonstrating operation | movement of the 2nd use subcarrier setting part which concerns on 3rd Embodiment. It is a figure which shows an example of P-SCH used with the cell search method which concerns on the 4th Embodiment of this invention. It is a figure for demonstrating the radio | wireless frame in the cell search method which concerns on the 5th Embodiment of this invention. It is a figure which shows an example of P-SCH used with the cell search method which concerns on 5th Embodiment. It is a figure which shows the example of arrangement | positioning on the frequency axis of P-SCH and S-SCH in 6th Embodiment. In the sixth embodiment, the propagation path is estimated from the amplitude / phase difference for each subcarrier between the received signal c ′ of the PSCc on the same subcarrier and the code c held by the mobile station, and the received s1 ′ It is a figure which shows a mode that compensation for every subcarrier is performed. It is the conventional radio | wireless frame figure. It is a figure which shows an example of a structure of a cell.

Explanation of symbols

100 Base station equipment (base station)
101 Control Unit 102 Reception Antenna Unit 103 Reception Analog Circuit Unit 104 A / D Conversion Unit 105 Demodulation Processing Unit 106 Data Modulation Unit 107 Control Signal Modulation Unit 108 Synchronization Signal Generation Unit 109 Multiplex / Modulation Processing Unit 110 D / A Conversion Unit 111 Transmission Analog circuit unit 112 Transmitting antenna unit 200 Mobile station device (mobile station)
201 reception antenna unit 202 reception analog circuit unit 203 A / D conversion unit 204 synchronization unit 205 GI removal unit 206 S / P conversion unit 207 FFT unit 208 propagation path estimation unit 209 demodulation unit 210 modulation unit 211 IFFT unit 212 P / S conversion Unit 213 GI addition unit 214 D / A conversion unit 215 transmission analog circuit unit 216 transmission antenna unit 217 control unit 301 first correlator 302 second correlator 303 third correlator 304 first buffer 305 second Buffer 306 Third buffer 307 Maximum value detector 308 Received power measurement unit 309, 405, 501 Used subcarrier setting unit 401 First maximum value detector 402 Second maximum value detector 403 Third maximum value detector 404 comparison part

Claims (13)

A cell search method in a wireless communication system using a plurality of different PSCs as P-SCH for each sector,
The plurality of PSCs are set so that a part in each PSC is common, a common part in the plurality of PSCs and any one of the PSCs are selected, and a common part in the plurality of PSCs Alternatively, a cell search method characterized by performing propagation path estimation using any PSC.   2. The cell search method according to claim 1, wherein the position of the mobile station apparatus is estimated, and one of the plurality of PSCs and one of the PSCs is selected according to the estimation result. .   The cell search method according to claim 2, wherein the mobile station apparatus measures the received power of the received signal and estimates the position of the mobile station apparatus according to the magnitude of the received power.   The replica signal waveforms of the plurality of PSCs are held by the mobile station apparatus, and the movement is performed according to the magnitude of the correlation value between the plurality of PSCs received by the mobile station apparatus and the replica signal waveforms of the plurality of PSCs The cell search method according to claim 2, wherein the position of the station apparatus is estimated.   The replica signal waveforms of the plurality of PSCs are held by the mobile station apparatus, and the magnitude of the correlation value between the plurality of PSCs received by the mobile station apparatus and the replica signal waveforms of the plurality of PSCs, and the received time The cell search method according to claim 2, wherein the position of the mobile station apparatus is estimated according to   6. The cell search method according to claim 4, wherein a PSC having a maximum correlation value among the plurality of PSCs is selected as one of the PSCs. A base station apparatus of a wireless communication system using a plurality of different PSCs as P-SCH for each sector,
A synchronization signal generating unit that generates the plurality of PSCs, each of which is common in each PSC;
An output unit that outputs the plurality of PSCs generated by the synchronization signal generation unit for each sector. A base station apparatus of a wireless communication system using a plurality of different PSCs as P-SCH for each sector,
A synchronization signal generating unit that generates the plurality of PSCs, each of which is common in each PSC;
An output unit that outputs the plurality of PSCs generated by the synchronization signal generation unit for each sector;
The synchronization signal generator is
A base station apparatus characterized in that information having a high priority in cell search is arranged on a subcarrier sharing the PSC. A mobile station apparatus of a wireless communication system using a plurality of different PSCs as P-SCH for each sector,
A receiving unit that receives the plurality of PSCs set so that a part of each PSC is common;
A PSC that maximizes the correlation value between the plurality of PSCs and the replica signal waveforms of the plurality of PSCs is detected, and a sub-channel that is used for propagation path estimation by comparing the received power of the plurality of PSCs with a predetermined threshold value. A synchronization unit for determining a carrier;
A mobile station apparatus comprising: a propagation path estimation unit that performs propagation path estimation based on the subcarrier determined by the synchronization unit. A mobile station apparatus of a wireless communication system using a plurality of different PSCs as P-SCH for each sector,
A receiving unit that receives the plurality of PSCs set so that a part of each PSC is common;
The maximum correlation value of each PSC is detected from the correlation value between the plurality of PSCs and the replica signal waveforms of the plurality of PSCs, and is used for propagation path estimation by comparing the maximum correlation value of each PSC with a predetermined threshold value. A synchronization unit for determining a subcarrier to be
A mobile station apparatus comprising: a propagation path estimation unit that performs propagation path estimation based on the subcarrier determined by the synchronization unit. A mobile station apparatus of a wireless communication system using a plurality of different PSCs as P-SCH for each sector,
A receiving unit that receives the plurality of PSCs set so that a part of each PSC is common;
The maximum correlation value of each PSC and the detection timing of the maximum correlation value are detected from the correlation values of the plurality of PSCs and the replica signal waveforms of the plurality of PSCs, and the maximum correlation value and the maximum correlation value of each PSC are detected. A synchronization unit that determines a subcarrier to be used for channel estimation by comparing the detection timing with a predetermined threshold;
A mobile station apparatus comprising: a propagation path estimation unit that performs propagation path estimation based on the subcarrier determined by the synchronization unit. A mobile station apparatus of a wireless communication system using a plurality of different PSCs as P-SCH for each sector,
A receiving unit that receives the plurality of PSCs set so that a part of each PSC is common;
A mobile station apparatus comprising: a propagation path estimator that performs propagation path estimation of a signal that is common in a sector using PSCs of the common subcarriers. A mobile station apparatus of a wireless communication system using a plurality of different PSCs as P-SCH for each sector,
A receiving unit that receives the plurality of PSCs set so that a part of each PSC is common;
A propagation path estimator that performs propagation path estimation of information subcarriers that are part of the S-SCH and have high priority in cell search, using the PSC of some of the common subcarriers. A featured mobile station apparatus.

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