JP2007019799A - Base station apparatus, mobile station apparatus, and frame transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base station apparatus, a mobile station apparatus, and a frame transmission method capable of achieving high speed cell searching by reducing a time required for the cell searching. <P>SOLUTION: A base station 100 forms a frame arranged with a group pilot symbol comprising a pilot signal and a code group sequence for identifying a group of a base station scrambling code, forms a modified scrambling code from the base station scrambling code on the basis of a modified parameter corresponding to the number of the base station scrambling code, multiplies the modified scrambling code with the frame formed in this way, and transmits a frame multiplied with the modified scrambling code. Then a mobile station 200 uses a formed modified scrambling code replica to detect the modified scrambling code, and applies success/failure discrimination to the cell searching on the basis of the result of the detection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a base station apparatus that transmits a frame used for an initial cell search, a mobile station apparatus that receives the frame and performs an initial cell search, and a method for transmitting the frame.

  A mobile station such as a mobile phone can communicate by appropriately selecting and using a cell (base station) at power-on or handover. The selection of a cell by the mobile station is called cell search. In the initial cell search, an optimal cell to be connected when the mobile station is turned on is selected. Specifically, each cell is identified by a unique scrambling code, and cell search is performed by the mobile station detecting the scrambling code of the cell that transmits the signal with the highest received power in the downlink. .

  As a related art related to this, for example, a cell search method using a common pilot channel (CPICH) of one symbol is proposed as an initial cell search method in the OFCDM (Orthogonal Frequency and Code Division Multiplexing) method. (For example, refer nonpatent literature 1). This initial cell search is performed for the purpose of symbol timing synchronization, frame timing synchronization, and scrambling code identification.

  FIG. 15 shows the structure of a frame used in the conventional cell search method. As shown in the figure, a CPICH of one OFDM symbol is arranged at the head of the frame, and a DPCH in which a plurality of data channels, control channels and the like are multiplexed is arranged in the remaining symbols.

  The CPICH is created in the base station as follows. That is, in the first stage, as a pilot signal, a code group sequence corresponding to the base station scrambling code assigned to the base station (from chip GC (1) to chip GC (K / 2) in FIG. 16). Are prepared, and each of GC (1) to GC (K / 2) is repeated with repetition factor (RF) = 2. That is, the pilot signal takes a common form for each code group in which the base station scrambling codes are grouped. The code group sequence is a sequence having a sequence length K / 2 from GC (1) to GC (K / 2). Here, K represents the number of OFCDM subcarriers. The pilot symbol is composed of K symbols.

  In the second stage, the even-numbered symbols of the pilot signal prepared in the first stage are multiplied by each of the code group series GC (1) to GC (K / 2), and the odd-numbered symbols are multiplied by 1. To do. A signal obtained by this (sometimes referred to as “group pilot” in this specification) has a common form for each code group.

  Here, the group pilot obtained through the first stage and the second stage is actually created in a process as shown in FIG. That is, two symbols in the group pilot are formed from each symbol of the code group sequence, and the code group sequence symbol itself is applied to one of the two symbols of the group pilot, and the symbol of the code group sequence is assigned to the other. A square is applied.

  Next, in the third stage, the first half (S (1) to S (K / 2)) of the base station scrambling codes consisting of S (1) to S (K) is RF = 2 (repetition factor = 2). ) Is multiplied by the group pilot obtained in the second stage. Thereby, CPICH can be created. Note that the DPCH on which a normal data channel and control channel are carried is, as shown in FIG. 18, a base station scrambling code (S (1) ˜) for each data sequence of d (1) ˜d (K) which is one OFDM symbol. S (K)).

  A frame including CPICH and DPCH created in this way is transmitted by the base station, and the mobile station on the receiving side performs an initial cell search using the frame transmitted in this format. FIG. 19 shows operations in the initial cell search performed by the mobile station. As shown in the figure, the mobile station performs an initial cell search in three stages.

  Specifically, in the first stage, the mobile station detects OFDM symbol timing (FFT window timing) using the correlation characteristics of the OFDM guard interval (GI).

  In the second stage, the mobile station performs FFT processing at the FFT window timing detected in the first stage, and performs frame timing detection and code group identification using the signal after OFDM demodulation. At that time, the above-described configuration of CPICH and the characteristics of the code group sequence multiplied by this are used. That is, since the adjacent subcarriers are multiplied by the same element of the scrambling code, the code group sequence GC can be identified using the correlation sequence obtained by performing the correlation calculation between the adjacent subcarriers. In other words, in order to identify the code group sequence, all the code group sequence candidates known to the mobile station are multiplied by the correlation sequence between adjacent subcarriers to obtain a correlation, and the timing at which the maximum correlation value is obtained is obtained. A code group sequence candidate detected as a frame timing and multiplied when obtaining the maximum correlation value is identified as a code group sequence.

  In the third stage, CPICH is extracted based on the frame timing detected in the second stage, and CPICH replicas are generated using all the codes belonging to the code group identified in the second stage. Then, the correlation between all replicas and the extracted CPICH is taken, and the scrambling code is identified by detecting the code that gives the maximum correlation value. The details of the above cell search procedure are described in Non-Patent Document 1.

In general, it is necessary to determine whether or not the scrambling code identified after the third stage is correct (verification).
Morita, Futaki, Minamisato, Takasaki, “Optimization of pilot channel in downlink OFDM wireless access and 4-stage cell search method and its characteristics,” RCS2004-254, January 2005

  However, in the conventional cell search, no consideration is given to the end determination. However, in the actual environment, the mobile station side does not know the correct scrambling code used on the base station side, so some termination determination is necessary. In a general termination determination method, CRC error check is performed by decoding BCH, DPCH, etc. using the scrambling code identified in the third stage as shown in FIG. If the CRC error check is OK, the mobile station completes the initial cell search and starts a predetermined procedure for connecting to the network. On the other hand, if the CRC error check is NG, it is determined that the initial cell search has failed, and it is necessary to start again from the first stage as shown in FIG. That is, the success / failure determination of the scrambling code identification in the third stage must be performed once until CRC error check such as BCH or DPCH, and there is a problem that it takes time to start a predetermined retry process.

  The present invention has been made in view of such points, and an object of the present invention is to provide a base station apparatus, a mobile station apparatus, and a frame transmission method capable of reducing the time required for cell search and realizing high-speed cell search. And

  The base station apparatus of the present invention forms a frame in which a group pilot symbol formed from a pilot signal and a code group sequence for identifying a group of base station scrambling codes assigned to the base station is arranged. Means, a modified scrambling code forming means for forming a modified scrambling code from the base station scrambling code based on a modification parameter corresponding to the number of the base station scrambling code, and the modification to the formed frame. A configuration is provided that includes multiplication means for multiplying the scrambling code and transmission means for transmitting the frame multiplied by the modified scrambling code.

  The mobile station apparatus of the present invention is a mobile station apparatus that performs cell search based on a frame transmitted from a base station apparatus, wherein the frame includes a pilot signal and a base station scrambling code assigned to the base station apparatus A group pilot symbol formed from a code group sequence for identifying a group of the base station and a modified scrambling formed from the base station scrambling code based on a modification parameter corresponding to the number of the base station scrambling code A ring code is multiplied, and a frame timing and the code group sequence are detected based on the correspondence table in which the base station scrambling code, the code group sequence, and the modification parameter are associated with each other, and the group pilot symbol. First detection to And forming a modified scrambling code candidate from a plurality of base station scrambling codes corresponding to the detected code group sequence based on the modified parameter, and using the modified scrambling code candidate, A configuration is adopted that includes second detection means for detecting, and determination means for determining success or failure of the cell search based on a detection result of the second detection means.

  The frame transmission method of the present invention includes a step of forming a frame in which a group pilot symbol formed from a pilot signal and a code group sequence for identifying a group of base station scrambling codes is arranged, and the base station scrambling Forming a modified scrambling code from the base station scrambling code, multiplying the formed frame by the modified scrambling code based on the modified parameter corresponding to the code number, and the modified scrambling Transmitting a frame multiplied by the code.

  According to the present invention, it is possible to provide a base station apparatus, a mobile station apparatus, and a frame transmission method capable of reducing the time required for cell search and realizing high-speed cell search.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiment, the same components are denoted by the same reference numerals, and the description thereof will be omitted because it is duplicated.

(Embodiment 1)
As shown in FIG. 1, base station 100 of Embodiment 1 includes an encoding section 105, a pilot signal generation section 110, a code group sequence generation section 115, a CPICH generation section 120, a frame configuration section 125, a scrambling section. Ring code generation section 130, scramble section 135, OFDM modulation section 140, GI (guard interval) insertion section 145, radio transmission section 150, radio reception section 155, demodulation section 165, and decoding section 170 Have.

  Encoding section 105 receives a transmission signal (DCH or the like), performs predetermined encoding, and outputs the encoded signal to frame configuration section 125.

  Pilot signal generation section 110 generates a pilot signal. Specifically, for example, pilot signal generation section 110 inputs a code group sequence number and a subcarrier block number N corresponding to a base station scrambling code assigned to base station 100, and corresponds to the code group number. GC (K / N) is generated from GC (1) of the chips of the code group series (the generated signal is referred to as “basic pilot signal”), and further, GC (1) to GC (K / N) Each of them is generated with repetition factor (RF) = N (the generated signal is referred to as “pilot signal”). The pilot signals in this generation example are GC (1) =... = GC (N), GC ((i-1) * N + 1) = ... = GC (i * N),. (K / N−1) * N + 1) =... = GC (K). (However, i = 1,..., K / N) The pilot signal is not limited to such a form, and may be a form common to all cells. However, even in the case of a pilot signal common to all cells, the pilot signals in the block are the same signal.

  The code group sequence generation unit 115 receives the code group sequence number and the number N of subcarrier blocks, and generates GC (K / N) from GC (1) of the code group sequence chips corresponding to the code group sequence number. , KK / N predetermined chips are added to generate a series of K chips. Specifically, for example, the chip immediately before GC (1) is set to 1, and 1 is put into N-2 chips from the chip next to GC (1). The same applies to GC (2) to GC (K / N). As another method, 1 may be inserted into N-1 chips from the chip next to GC (1), and the same may be applied to GC (2) to GC (K / N). As another method, 1 is put in the chip immediately before GC (1), and the combination of this 1, GC (1) is repeated N / 2 times, and from GC (2) to GC (K / N) May be the same. As another method, 1 is put in the chip immediately after GC (1), and this combination of GC (1) and 1 is repeated N / 2 times, and from GC (2) to GC (K / N) May be the same.

  Then, the code group sequence generation unit 115 outputs the generated sequence to the CPICH generation unit 120.

  CPICH generation unit 120 receives the pilot signal generated by pilot signal generation unit 110 and the sequence generated by code group sequence generation unit 115 and multiplies the pilot signal and the sequence to generate a “group pilot”. Is generated. As described above, this “group pilot” has a common form for each code group.

  Frame configuration section 125 inputs the encoded signal from encoding section 105 and the group pilot from CPICH generation section 120. Then, frame configuration section 125 forms a frame having a configuration in which the group pilot is arranged at the head and the encoded signal (data) is arranged in the rest (see FIG. 2). Frame configuration section 125 then outputs an OFDM symbol in units of OFDM symbols that are N subcarrier symbols.

  The scrambling code generation unit 130 generates a base station scrambling code block corresponding to the base station scrambling code number among the base station scrambling codes assigned to the own device. That is, the base station scrambling code number is divided into M sets (aggregates), and the base station scrambling code is also divided into M blocks, and a base station scrambling code number and a set of base station scrambling code numbers ( Hereinafter, a correspondence table between the base station scrambling code block and a base station scrambling code block is prepared, and the scrambling code generation unit 130 sets the base station scrambling code number to a set to which the base station scrambling code number belongs. A corresponding base station scrambling code block is generated. Specifically, for example, when the base station scrambling code number is divided into two sets, when the base station scrambling code number is an even number, a base station scrambling code block of the first half of the base station scrambling code is generated, When the station scrambling code number is an odd number, a base station scrambling code block in the latter half of the base station scrambling code is generated (see FIG. 3). The set number M of base station scrambling codes is actually determined from a repetition factor determined in advance by the system based on the cell radius covered by base station 100, the transmission power of CPICH to be transmitted, and the like.

  Then, scrambling code generation section 130 performs repetition with the repetition factor (RF) as M, and outputs the sequence obtained by repetition to scrambling section 135.

  That is, the scrambling code generation unit 130 applies a modification corresponding to the base station scrambling code set to the base station scrambling code to form a modified scrambling code to be multiplied by the group pilot. Specifically, a correspondence table in which a base station scrambling code number, base station scrambling code set identification information, and a modification method are associated with each other is prepared, and the scrambling code generation unit 130 includes a base station scrambling code. A modified scrambling code is formed by a modification method corresponding to the set identification information. For example, the identification information of the base station scrambling code block forms a modified scrambling code from the base station scrambling code using the base station scrambling code block. Available as In the above specific example, the sequence obtained by repetition corresponds to the modified scrambling code.

  The scramble unit 135 receives a sequence (modified scrambling code) that has been repeated from the scrambling code generation unit 130 and has the same length as the base station scrambling code, and the base station scrambling code. Transmission data is input in units of OFDM symbols, and spreading is performed by multiplying the above sequences for each OFDM symbol. Specifically, scrambling section 135 multiplies the modified scrambling code when an OFDM symbol corresponding to a group pilot is input, and base station scrambling code when an OFDM symbol corresponding to DPCH is input. Multiply The scrambled transmission data is output to OFDM modulation section 140.

  OFDM modulation section 140 receives the scrambled transmission data, performs OFDM modulation, and outputs the result to GI insertion section 145.

  The GI insertion unit 145 inserts a guard interval for each OFDM symbol, and outputs the signal after the insertion of the guard interval to the radio transmission unit 150.

  Radio transmission section 150 receives the signal after the insertion of the guard interval from GI insertion section 145, performs RF processing such as up-conversion, and transmits it through the antenna.

  Radio receiving section 155 receives a signal from a mobile station via an antenna, performs RF processing such as down-conversion, and outputs the RF-processed signal to demodulation section 165.

  The demodulator 165 performs demodulation by performing synchronous detection corresponding to a predetermined modulation method.

  Decoding section 170 receives the demodulated signal from demodulation section 165, performs appropriate error correction decoding, and extracts the received signal.

  As shown in FIG. 4, mobile station 200 according to Embodiment 1 includes reception control section 205, radio reception section 210, symbol timing detection section 215, GI removal section 220, FFT processing section 225, and adjacent subcarriers. Correlation unit 230, code group sequence replica generation unit 235, code group sequence correlation unit 240, frame timing / code group detection unit 245, scrambling code identification unit 250, scrambling code replica generation unit 255, cell A search success / failure determination unit 260, a descrambling unit 265, a decoding unit 270, a CRC check unit 275, an encoding unit 280, a modulation unit 285, and a wireless transmission unit 295 are included.

  The reception control unit 205 receives the radio reception unit 210 and the FFT processing unit 225 according to the state of the mobile station 200, that is, the number of stages in the initial cell search mode or the normal reception mode, or the success or failure of code identification. The output destination of the output signal from is controlled. Specifically, output destination command signals are output to the wireless reception unit 210 and the FFT processing unit 225 to control the output destinations of the output signals from the wireless reception unit 210 and the FFT processing unit 225. The content of the output destination command signal to the radio reception unit 210 is that the symbol timing detection unit 215 is the output destination when the mobile station 200 is in the first stage of the initial cell search mode. If it is other than one stage, the contents indicate that the GI removal unit 220 is the output destination. The reception control unit 205 receives the frame timing information when the frame timing / code group detection unit 245 detects the frame timing. The reception control unit 205 outputs an output destination command signal that controls the output destination of the output signal of the FFT processing unit 225 based on the frame timing information. In addition, when the cell search success / failure determination unit 260 determines that the initial cell search has failed, the reception control unit 205 needs to detect the first stage symbol timing again. Therefore, the cell search success / failure determination unit 260 receives the search retry signal. And the output destination of the output signal of the wireless reception unit 210 is controlled.

  The radio reception unit 210 receives a signal from the base station 100 via an antenna and performs RF processing such as down-conversion. Then, the wireless reception unit 210 outputs a signal after RF processing to the output destination indicated by the output destination command signal from the reception control unit 205.

  Symbol timing detection section 215 receives a signal after RF processing from radio reception section 210 when mobile station 200 is in the first stage of the initial cell search mode. The symbol timing detection unit 215 takes the guard interval correlation and detects the OFDM symbol timing using the correlation characteristics of the guard interval in the OFDM symbol. This OFDM symbol timing is an FFT window timing for performing FFT. Then, the symbol timing detection unit 215 outputs a result of the detected symbol timing to the GI removal unit 220 and also notifies the fact that the symbol timing has been detected, that is, the first stage of the cell search has been completed. A stage end notification signal is output to reception control section 205. In this specification, a period between successive OFDM symbol timings is referred to as an “OFDM symbol period”.

  GI removal section 220 removes the guard interval from the received signal after RF processing in accordance with the OFDM symbol timing from symbol timing detection section 215, and outputs the result to FFT processing section 225.

  The FFT processing unit 225 inputs the received signal after removal of the guard interval from the GI removal unit 220 in units of OFDM symbols, and performs FFT processing on this input signal. Then, the FFT processing unit 225 outputs the signal after the FFT processing to an output destination corresponding to the output destination command signal from the reception control unit 205. Specifically, when the current state of the mobile station 200 is the second stage of cell search, the FFT processing unit 225 receives an output destination command signal indicating that the adjacent subcarrier correlation unit 230 is an output destination. Then, the signal after the FFT processing is output to the adjacent subcarrier correlation unit 230. Further, when the current state of the mobile station 200 is the third stage of cell search, the FFT processing unit 225 receives an output destination command signal indicating that the scrambling code identification unit 250 is an output destination, and receives it. Based on the frame timing information from the control unit 205, the OFDM symbol including the “group pilot” after the FFT processing and disposed at the head of the frame is output to the scrambling code identification unit 250. Also, the FFT processing unit 225 outputs from the reception control unit 205 other than the output destination command signal that is the output destination of the adjacent subcarrier correlation unit 230 and the output destination command signal that the scrambling code identification unit 250 is the output destination. When the previous command signal is input, the signal after the FFT processing is output to the descrambling unit 265.

  Adjacent subcarrier correlation section 230 receives the signal after FFT processing from FFT processing section 225, correlates subcarrier signals adjacent in the frequency direction in each OFDM symbol section, and at least NS + 1st subcarrier signal and NS + 2 A correlation sequence is calculated for each OFDM symbol interval from the correlation value with the first subcarrier signal (see FIG. 5). S is an integer of 1 or more and K / N or less. This correlation sequence calculation is performed over one frame.

  The case where N = 4 will be specifically described with reference to FIG. Here, the sequence generated by the code group sequence generation unit 115 multiplied by the frame transmitted from the base station 100 on the transmission side is the state shown in the upper part of FIG. It is assumed that the input signal is multiplied by the series. In the figure below, chip numbers are shown.

  At this time, if the adjacent subcarrier correlation unit 230 calculates a correlation sequence for each OFDM symbol section from the correlation value between the NS + 1st subcarrier signal and the NS + 2nd subcarrier signal, the correlation sequence is used by the base station 100. Code group series. The code group sequence is also obtained from the correlation value between the NS + 2nd subcarrier signal and the NS + 3rd subcarrier signal. In this case, the correlation value between the NS + 1st subcarrier signal and the NS + 2nd subcarrier signal and the NS + 2nd subcarrier signal are also obtained. By adding the correlation value between the signal and the NS + third subcarrier signal, the code group sequence can be obtained more accurately. However, here, it is sufficient that the code group sequence can be obtained by using the correlation value of the adjacent subcarrier signal corresponding to the format of the sequence generated by the code group sequence generation unit 115 of the base station 100, and is limited to the above method. Is not to be done.

  The calculated correlation sequence for each OFDM symbol section is output to code group sequence correlation section 240.

  The code group sequence replica generation unit 235 generates all the code group sequences predetermined in the system and outputs them to the code group sequence correlation unit 240.

  The code group sequence correlator 240 receives the correlation sequence calculated by the adjacent subcarrier correlation unit 230 and the code group sequence from the code group sequence replica generation unit 235, and performs a correlation operation between the correlation sequence and all code group sequences. I do. This correlation calculation is performed for all OFDM symbols in one frame. Note that this correlation calculation may be performed for all OFDM symbols of a plurality of frames, and the correlation value may be averaged between frames to improve the performance.

  The frame timing / code group detection unit 245 receives the correlation value or average correlation value for one frame from the code group sequence correlation unit 240 and detects the maximum correlation value. Frame timing / code group detection section 245 simultaneously detects the OFDM symbol timing at which the maximum correlation value is obtained and the code group sequence multiplied when obtaining the maximum correlation value. Then, the frame timing / code group detection unit 245 outputs the detected frame timing information to the scrambling code identification unit 250 and the reception control unit 205, and code group sequence identification information (for example, for identifying the detected code group sequence). Code group sequence number) is output to scrambling code identification section 250.

  The scrambling code replica generation unit 255 inputs the code group sequence identification information via the scrambling code identification unit 250, and obtains all the base station scrambling code replicas corresponding to the code group indicated by the code group sequence identification information. Generate. Specifically, all base station scrambling codes corresponding to the code group and N modified scrambling code replicas from each base station scrambling code are generated. Here, the N modified scrambling codes are SC (1) to SC (K / N) and SC (K / N + 1) to SC (2K) which are the base station scrambling code blocks of the original scrambling code. / N),..., SC ((N−1) * K / N + 1) to SC (K) are codes obtained by repetition with a repetition factor N.

  That is, the scrambling code replica generation unit 255 converts the base station scrambling code corresponding to the code group indicated by the code group sequence identification information detected by the frame timing / code group detection unit 245 using all the deformation methods. Then, a modified scrambling code replica corresponding to each modification method is generated. Then, when identifying the base station scrambling code, a modified scrambling code replica of the candidate base station scrambling code is output to scrambling code identification section 250.

  Incidentally, when the number M of scrambling code sets is 4 and 16 base station scrambling codes are included in one code group, it is obtained by the repetition output from the scrambling code replica generation unit 255. The number of sequences (modified scrambling code replicas) is 64.

  The scrambling code identification unit 250 repeats each base station scrambling code block received from the scrambling code replica generation unit 255 for the OFDM symbol including the group pilot located at the head of the frame received from the FFT processing unit 225. Are multiplied by the series obtained (i.e., modified scrambling code replicas) to perform correlation calculation. Then, the base station scrambling code that is the basis of the base station scrambling code block corresponding to the “modified scrambling code replica” that provides the largest value among the obtained correlation values is identified. Then, the base station scrambling code block identification information used for identifying the base station scrambling code and the identified base station scrambling code number are output to cell search success / failure determination section 260. Further, the scrambling code identification unit 250 causes the scrambling code replica generation unit 255 to generate the identified base station scrambling code and outputs it to the cell search success / failure determination unit 260.

  That is, the scrambling code identification unit 250 uses the deformation method identification information used when the “modified scrambling code replica” that provides the largest correlation value is formed, and the “modified scrambling code replica”. ”Is output to the cell search success / failure determination unit 260.

  The cell search success / failure determination unit 260 is the same as the base station 100 has, a correspondence table that associates base station scrambling code numbers, base station scrambling code set identification information, and modification methods, specifically, Holds a correspondence table of base station scrambling code numbers, base station scrambling sets, and base station scrambling code blocks. Then, the cell search success / failure determination unit 260 determines whether or not the set of the base station scrambling code number and the base station scrambling code block received from the scrambling identification unit 250 is associated in the correspondence table. .

  As a result of the determination, if the combination of the base station scrambling code number received from the scrambling code identification unit 250 and the base station scrambling code block is associated in the correspondence table, the cell search success / failure determination unit 260 It is determined that the cell search is successful, and the base station scrambling code received from the scrambling code identification unit 250 is output to the descrambling unit 265.

  On the other hand, as a result of the determination, if the combination of the base station scrambling code number received from the scrambling identification unit 250 and the base station scrambling code block is not associated in the correspondence table, the cell search success / failure determination unit 260 Determines that the cell search has failed, and outputs a cell search retry signal to the reception control unit 205 so as to start the cell search again from the first stage. Conventionally, the mobile station 200 can determine the success or failure of the cell search in the previous stage of the CRC check, whereas the mobile station 200 can determine the success or failure of the cell search in the previous stage of the CRC check. Can be speeded up. When receiving the cell search retry signal, the reception control unit 205 outputs to the radio reception unit 210 an output destination command signal indicating that the symbol timing detection unit 215 is an output destination.

  The descrambling unit 265 inputs the signal after the FFT processing from the FFT processing unit 225, performs the descrambling by multiplying the base station scrambling code received from the cell search success / failure determination unit 260, and decodes the descrambled signal To the unit 270.

  Decoding section 270 receives the descrambled signal, performs appropriate error correction decoding, and outputs the error correction decoding result to CRC check section 275.

  The CRC check unit 275 performs a CRC error check on the error correction decoding result from the decoding unit, and determines that the initial cell search is completed when there is no error. On the other hand, if an error exists, the CRC check unit 275 outputs a CRC error check result to the reception control unit 205 in order to start the initial cell search again from the first stage. When receiving the CRC error check result output when this error exists, the reception control unit 205 outputs to the wireless reception unit 210 an output destination command signal indicating that the symbol timing detection unit 215 is the output destination. It will be.

  Encoding section 280 receives a transmission signal such as DPCH, performs predetermined encoding, and outputs the encoded signal to modulation section 285.

  Modulation section 285 performs processing such as predetermined multi-level modulation and outputs a modulated signal to radio transmission section 295.

  The wireless transmission unit 295 receives the modulation signal from the modulation unit 285, performs RF processing such as up-conversion, and transmits it through the antenna.

  Next, the operation of mobile station 200 having the above configuration will be described with reference to FIG.

  In Step ST1001, the symbol timing detection section 215 of the mobile station 200 takes the guard interval correlation and detects the OFDM symbol timing using the correlation characteristics of the guard interval in the OFDM symbol. This is the first stage of cell search.

  In Step ST1002, the adjacent subcarrier correlation section 230 receives the signal after FFT processing from the FFT processing section 225, correlates between the subcarrier signals adjacent in the frequency direction in each OFDM symbol section, and at least the NS + 1th sub A correlation sequence is calculated (correlation calculation) for each OFDM symbol section from the correlation value between the carrier signal and the NS + second subcarrier signal.

  In step ST1003, code group sequence correlator 240 receives the correlation sequence calculated by adjacent subcarrier correlator 230 and the code group sequence from code group sequence replica generator 235, and the correlation sequence and all code group sequences. And the correlation calculation. This correlation calculation is performed for all symbols in one frame. The correlation calculation may be performed over a plurality of frames and averaged between the frames.

  Frame timing / code group detection section 245 receives the correlation value (or average correlation value) from code group sequence correlation section 240 and detects the maximum correlation value. Then, the frame timing / code group detection unit 245 detects the symbol timing at which the maximum correlation value is obtained and the code group sequence that is multiplied when obtaining the maximum correlation value. That is, in step ST1004, frame timing / code group detection section 245 identifies frame timing and code group series. The symbol position where the maximum correlation value is obtained in the virtual frame may be identified as the frame timing, and the subsequent signal processing may be performed after adjusting the virtual frame position to the identified frame timing.

  The scrambling code identification unit 250 repeats each base station scrambling code block received from the scrambling code replica generation unit 255 for the OFDM symbol including the group pilot located at the head of the frame received from the FFT processing unit 225. The N sequences (that is, modified scrambling code replicas) obtained by the above are respectively multiplied and correlation calculation is performed. Then, the base station scrambling code that is the basis of the base station scrambling code block corresponding to the “modified scrambling code replica” that provides the largest value among the obtained correlation values is identified (step ST1005).

  Then, the base station scrambling code block identification information used for identifying the base station scrambling code and the identified base station scrambling code number are output to cell search success / failure determination section 260. Further, the scrambling code identification unit 250 causes the scrambling code replica generation unit 255 to generate the identified base station scrambling code and outputs it to the cell search success / failure determination unit 260.

  In Step ST1006, the cell search success / failure determination unit 260 associates the set of the base station scrambling code number received from the scrambling identification unit 250 and the identification information of the base station scrambling code block in the correspondence table. Determine whether or not.

  As a result of the determination, when the set of the base station scrambling code number received from the scrambling identification unit 250 and the base station scrambling code block identification information is associated in the correspondence table (step ST1006: YES), The cell search success / failure determination unit 260 determines that the cell search is successful, and outputs the base station scrambling code received from the scrambling code identification unit 250 to the descrambling unit 265.

  In step ST1007, decoding section 270 inputs the broadcast channel (BCH) signal that has been descrambled by descrambling section 265, performs appropriate error correction decoding, and sends the error correction decoding result to CRC check section 275. Output.

  In step ST1008, CRC check section 275 performs a CRC error check on the error correction decoding result from decoding section 270. If there is no error (step ST1008: YES), it is determined that the initial cell search has been completed. The cell search process ends.

  As a result of the determination, when the combination of the base station scrambling code number received from the scrambling identification unit 250 and the base station scrambling code block identification information is not associated in the correspondence table (step ST1006: NO), The cell search success / failure determination unit 260 determines that the cell search has failed, outputs a cell search retry signal to the reception control unit 205, and starts the cell search again from the first stage.

  As described above, according to Embodiment 1, group pilot symbols formed from a pilot signal and a code group sequence for identifying a group of base station scrambling codes assigned to the base station 100 are arranged in base station 100. A frame composing unit 125 that forms the generated frame, a scrambling code generating unit 130 that forms a modified scrambling code from the base station scrambling code based on the modification parameter corresponding to the base station scrambling code number, A scramble unit 135 that multiplies the frame formed by the frame configuration unit 125 by the modified scrambling code formed by the scrambling code generation unit 130, and a wireless transmission unit 150 that transmits the frame multiplied by the modified scrambling code. And provide .

  By doing so, the base station 100 transmits a frame obtained by multiplying the modified scrambling code obtained by modifying the base station scrambling code based on the modified parameter corresponding to the base station scrambling code number of its own device. Whether the base station scrambling code specified on the frame receiving side is actually the base station scrambling code used in the base station 100, that is, whether the cell search is successful, and the specified base station scrambling code This determination can be made based on the correspondence relationship with the deformation parameter used when the base station scrambling code is transformed into the modified scrambling code. As a result, it is possible to determine the success of the cell search without performing the CRC check used for the success determination of the conventional cell search. If the cell search fails, the cell search can be performed again earlier. Speeding up can be realized.

  The deformation parameter is a base station scrambling code block obtained by dividing a base station scrambling code into a predetermined number, and the scrambling code generation unit 130 adds a base station scrambling code block corresponding to a base station scrambling code number. A modified scrambling code is formed by performing repetition according to a predetermined number.

  Further, according to Embodiment 1, group pilot symbols formed from a pilot signal and a code group sequence for identifying a group of base station scrambling codes assigned to base station 100 are arranged in mobile station 200. A radio reception unit 210 that receives a frame multiplied by a modified scrambling code formed from the base station scrambling code based on a modified parameter corresponding to the base station scrambling code number, and a base station scrambling code A correspondence table in which code group sequences are associated with deformation parameters, a frame timing / code group detection unit 245 that detects frame timing and code group sequences based on group pilot symbols, and a frame timing / code A modified scrambling code replica is formed based on a modified parameter from a plurality of base station scrambling codes corresponding to the code group sequence detected by the group detection unit 245, and the modified scrambling code is generated using the modified scrambling code replica. A scrambling code replica generation unit 255 and a scrambling code identification unit 250 to detect, and a cell search success / failure determination unit 260 that determines the success or failure of the cell search based on the detection result of the scrambling code identification unit 250 are provided.

  In this way, a frame obtained by multiplying the base station scrambling code by modifying the base station scrambling code based on the base station scrambling code number and the modified scrambling code is received. The success or failure of the cell search can be determined based on this. As a result, it is possible to determine the success of the cell search without performing the CRC check used for the success determination of the conventional cell search, so that if it fails, the cell search can be restarted at an early stage. Speeding up can be realized.

  In addition, by dividing the base station scrambling code number into a plurality of sets and changing the deformation parameters according to this set, it is possible to determine the success or failure of the cell search than when changing the deformation parameters for every base station scrambling code. Although the accuracy is lowered, the processing amount is reduced, so that the cell search can be further speeded up.

  The scrambling code identification unit 250 performs a correlation operation between each of the formed modified scrambling codes and the group pilot, and detects a modified scrambling code having the largest obtained correlation value.

  The scrambling code identification unit 250 identifies the base station scrambling code and the deformation parameter corresponding to the detected modified scrambling code, and the cell search success / failure determination unit 260 identifies the identified base station scrambling code. The success or failure of the cell search is determined based on whether or not the transformation parameters are associated with each other in the correspondence table.

(Embodiment 2)
In the first embodiment, the base station 100 multiplies the transmission frame with the modified scrambling code formed by applying the modification corresponding to the base station scrambling code set assigned to the base station to the base station scrambling code. The mobile station 200 which is the frame receiving side shows the correspondence between the modified scrambling code modified by the frame transmitted to the frame transmitted at the end of the cell search determination and the set of identified base station scrambling code numbers. Used to determine the end of the search. On the other hand, in the second embodiment, instead of the base station scrambling code set, the correspondence between the code group sequence set obtained by dividing the code group sequence into a plurality of sets and the modification method is determined as the end of cell search To use.

  As shown in FIG. 8, base station 300 of Embodiment 2 has scrambling code generation section 310.

  The scrambling code generator 310 generates a base station scrambling code block corresponding to the code group sequence set corresponding to the base station scrambling code among the base station scrambling codes assigned to the own device. That is, the code group sequence is divided into M sets, and the base station scrambling code is also divided into M blocks. The code group sequence number and the correspondence between this code group sequence set and the base station scrambling code block A table is prepared, and scrambling code generation section 310 generates a base station scrambling code block corresponding to a code group sequence set corresponding to the base station scrambling code. Specifically, for example, when the code group sequence is divided into two sets, when the number of the code group sequence corresponding to the base station scrambling code is an even number, the base station scrambling code block in the first half of the base station scrambling code is When the code group sequence number is an odd number, a base station scrambling code block in the latter half of the base station scrambling code is generated.

  Then, scrambling code generation section 310 performs repetition using M as the number of blocks of the base station scrambling code as a repetition factor (RF), and outputs the sequence obtained by repetition to scrambling section 135.

  That is, scrambling code generation section 310 applies a modification according to the code group sequence set corresponding to the base station scrambling code to the base station scrambling code to form a modified scrambling code. Specifically, a correspondence table is prepared in which a base station scrambling code, a code group sequence number to which the base station scrambling code belongs, a code group sequence set identification information, and a modification method are associated with each other. The code generation unit 310 forms a modified scrambling code by a modification method corresponding to the code group sequence set identification information corresponding to the base station scrambling code. The identification information of the base station scrambling code block is transformed from the base station scrambling code by performing repetition using M as the repetition factor (RF) using the base station scrambling code block. Since the scrambling code is formed, it can be used as modification method identification information or modification method parameters. In the above specific example, the sequence obtained by repetition corresponds to the modified scrambling code.

  As shown in FIG. 9, mobile station 400 of Embodiment 2 includes scrambling code replica generation section 410, scrambling code identification section 420, and cell search success / failure determination section 430.

  Scrambling code replica generation section 410 inputs code group sequence identification information via scrambling code identification section 420, and base station scrambling related to the base station scrambling code corresponding to the code group indicated by this code group sequence identification information Generate a ring code block. Then, the base station scrambling code block number M is set to RF, each base station scrambling code block is repeated, and the sequence obtained by the repetition is output to the scrambling code identification unit 420.

  That is, the scrambling code replica generation unit 410 corresponds the base station scrambling code corresponding to the code group indicated by the code group sequence identification information (code group sequence number) to the code group sequence set including the code group sequence number. Then, a modified scrambling code replica is generated by using the modification method.

  Incidentally, when the number M of code group sequence sets is 4 and 16 base station scrambling codes are included in one code group, the repetition output from the scrambling code replica generation unit 255 causes the above repetition. The number of obtained sequences (modified scrambling code replicas) is 16. By associating the code group sequence set with the modification method in this way, it is not necessary to generate a modified scrambling code replica using all the modification methods, so the processing amount is reduced and the cell search is made faster. can do.

  The scrambling code identification unit 420 repeats each base station scrambling code block received from the scrambling code replica generation unit 410 for the OFDM symbol including the group pilot located at the head of the frame received from the FFT processing unit 225. Are multiplied by the series obtained (i.e., modified scrambling code replicas) to perform correlation calculation. Then, the base station scrambling code that is the base of the base station scrambling code block corresponding to the “modified scrambling code replica” that is equal to or greater than the predetermined value among the obtained correlation values is identified. To do. Then, code group sequence set identification information corresponding to the base station scrambling code block used for identification of the base station scrambling code is output to cell search success / failure determination section 430. Further, scrambling code identification section 420 causes scrambling code replica generation section 410 to generate the identified base station scrambling code and outputs it to cell search success / failure determination section 430.

  The cell search success / failure determination unit 430 receives the code group sequence set identification information only when the correlation value obtained by the scrambling code identification unit 420 has a predetermined value or more. When the identification information is received, it is determined that the cell search is successful, and the base station scrambling code received from the scrambling code identification unit 420 is output to the descrambling unit 265. On the other hand, the cell search success / failure determination unit 430 determines that the cell search has failed when the correlation value obtained by the scrambling code identification unit 420 does not have a predetermined value or more, and performs the cell search. The cell search retry signal is output to the reception control unit 205 so as to start again from the first stage.

  As described above, according to the second embodiment, group pilot symbols formed from a pilot signal and a code group sequence for identifying a group of base station scrambling codes assigned to the base station 300 are arranged in base station 300. A frame configuration unit 125 that forms a generated frame, a scrambling code generation unit 310 that forms a modified scrambling code from the base station scrambling code based on a modification parameter corresponding to the number of the base station scrambling code, A scramble unit 135 that multiplies the frame formed by the frame configuration unit 125 by the modified scrambling code formed by the scrambling code generation unit 310, and a wireless transmission unit 150 that transmits the frame multiplied by the modified scrambling code. And provide The deformation parameters are different for each code group sequence.

  By doing so, the base station 300 transmits a frame obtained by multiplying the modified scrambling code obtained by transforming the base station scrambling code based on the modified parameter corresponding to the base station scrambling code number of its own device, and Since the deformation parameters differ for each code group sequence, the reception parameters of this frame can narrow down the deformation parameters that are considered to be used in the base station 300 when the group code sequence is detected. As a result, the cell search can be further speeded up as compared with the base station 100 of the first embodiment.

  Further, according to Embodiment 2, group pilot symbols formed from a pilot signal and a code group sequence for identifying a group of base station scrambling codes assigned to base station 300 are arranged in mobile station 400. A radio reception unit 210 that receives a frame multiplied by a modified scrambling code formed from the base station scrambling code based on a modified parameter corresponding to the base station scrambling code number, and a base station scrambling code A correspondence table in which code group sequences are associated with deformation parameters, a frame timing / code group detection unit 245 that detects frame timing and code group sequences based on group pilot symbols, and a frame timing / code A modified scrambling code replica is formed based on a modified parameter from a plurality of base station scrambling codes corresponding to the code group sequence detected by the group detection unit 245, and the modified scrambling code is generated using the modified scrambling code replica. A scrambling code replica generation unit 410 and a scrambling code identification unit 420 to detect, and a cell search success / failure determination unit 430 that determines the success or failure of the cell search based on the detection result of the scrambling code identification unit 420 are provided.

  The deformation parameter differs for each code group sequence, and the scrambling code replica generation unit 410 and the scrambling code identification unit 420 detect the detected code from a plurality of base station scrambling codes corresponding to the detected code group sequence. A modified scrambling code replica is formed based on a modified parameter corresponding to the group sequence, a modified scrambling code is detected using the modified scrambling code replica, and the cell search success / failure determination unit 430 includes a scrambling code identification unit 420. When the modified scrambling code is detected, it is determined that the cell search is successful. When the scrambling code identification unit 420 cannot detect the modified scrambling code, the cell search is determined to have failed. To.

  In this way, the mobile station 400 transmits a frame obtained by multiplying the base station 300 by the modified scrambling code obtained by modifying the base station scrambling code based on the base station scrambling code number and the corresponding modification parameter. Since frames with different deformation parameters for each code group sequence are received, it is possible to narrow down the deformation parameters that are considered to be used in the base station 300 when the group code sequence is detected. Then, a modified scrambling code replica is formed after reducing the number of deformation parameters, and the scrambling code identification unit 420 performs direct cell search based on the result of detecting the modified scrambling code using the modified scrambling code replica. Success or failure can be determined. As a result, the cell search can be further speeded up as compared with the base station 100 of the first embodiment.

(Embodiment 3)
In the first embodiment, the shape of the modified scrambling code is not particularly limited. On the other hand, in the third embodiment, the shape of the modified scrambling code formed from one base station scrambling code is the same in the order of chips and only the phase is different. As an example of the modified scrambling code of the third embodiment, the first half part and the second half part of two lower half sequences of the Hadamard sequence shown in FIG. 11 can be cited.

  As shown in FIG. 10, base station 500 of Embodiment 3 has scrambling code generation section 510.

  The scrambling code generation unit 510 generates a base station scrambling code block corresponding to the base station scrambling code number among the base station scrambling codes assigned to the own device. That is, the base station scrambling code number is divided into M sets, and the base station scrambling code is also divided into M blocks. The base station scrambling code number, the scrambling code set, and the base station scrambling code block The scrambling code generation unit 510 generates a base station scrambling code block corresponding to the base station scrambling code set to which the base station scrambling code number belongs.

  Here, the base station scrambling code blocks generated by the scrambling code generation unit 510 from one base station scrambling code have the same chip arrangement order and differ only in phase.

  Specifically, for example, when base station scrambling code numbers are divided into two sets, when the base station scrambling code number is an even number, the first half of one of the two lower half sequences of the Hadamard sequence shown in FIG. A base station scrambling code block is generated. When the base station scrambling code number is an odd number, the latter half is generated as a base station scrambling code block.

  Then, scrambling code generation section 510 performs repetition using M, which is the number of base station scrambling code blocks, as a repetition factor (RF), and outputs a sequence obtained by repetition to scrambling section 135.

  That is, scrambling code generation section 510 applies a modification according to the scrambling code set to the base station scrambling code to form a modified scrambling code. Specifically, a correspondence table in which the base station scrambling code number, the scrambling code set identification information, and the modification method are associated with each other is prepared, and the scrambling code generation unit 510 includes the scrambling code set identification information, A modified scrambling code is formed by a corresponding deformation method. The changed scrambling codes obtained from one base station scrambling code have the same chip arrangement order and different phases only.

  As shown in FIG. 12, mobile station 600 according to Embodiment 3 includes scrambling code replica generation section 610 and scrambling code identification section 620.

  Scrambling code replica generation section 610 receives code group sequence identification information via scrambling code identification section 620, and base station scrambling related to the base station scrambling code corresponding to the code group indicated by the code group sequence identification information Generate a ring code block. Then, repetition of each base station scrambling code block is performed with M as the number of scrambling code sets M, and the sequence obtained by the repetition is output to scrambling code identification section 620.

  That is, scrambling code replica generation section 610 generates a modified scrambling code replica by modifying all of the base station scrambling codes corresponding to the code group indicated by the code group sequence identification information using one modification method.

  Incidentally, when the number M of scrambling code sets is 4 and 16 base station scrambling codes are included in one code group, it is obtained by the repetition output from the scrambling code replica generation unit 255. The number of sequences (that is, modified scrambling code replicas) is 16.

  The scrambling code identification unit 620 repeats each base station scrambling code block received from the scrambling code replica generation unit 610 for the OFDM symbol including the group pilot located at the head of the frame received from the FFT processing unit 225. Each of the sequences (modified scrambling code replicas) obtained by (2) is multiplied and correlation calculation is performed, and the phase difference between the modified scrambling code and the modified scrambling code replica multiplied by the base station 500 on the transmission side is calculated. Make a decision. Based on the determined phase difference determination result, the modified method used in the base station 500 on the transmission side is specified, and the largest value among the obtained correlation values is obtained “modified scrambling code replica The base station scrambling code that is the base of the base station scrambling code block corresponding to "is identified.

  Then, scrambling code identification section 620 outputs the identified modification method and the identified base station scrambling code number to cell search success / failure determination section 260. Further, the scrambling code identification unit 620 causes the identified base station scrambling code to be generated by the scrambling code replica generation unit 610 and outputs it to the cell search success / failure determination unit 260.

  That is, the scrambling code identification unit 620 forms the “modified scrambling code replica” in which the identification information of the modification method identified based on the phase difference determination result and the largest value among the correlation values are obtained. The base station scrambling code number used is output to cell search success / failure determination section 260.

  Thus, according to Embodiment 3, group pilot symbols formed from a pilot signal and a code group sequence for identifying a group of base station scrambling codes assigned to the own apparatus are arranged in base station 500. A frame configuration unit 125 that forms the generated frame, a scrambling code generation unit 510 that forms a modified scrambling code from the base station scrambling code based on a modification parameter corresponding to the base station scrambling code number, A scramble unit 135 that multiplies the frame formed by the frame configuration unit 125 by the modified scrambling code formed by the scrambling code generation unit 510, and a radio transmission unit 150 that transmits the frame multiplied by the modified scrambling code. And provide The modified scrambling code is made of the same chip row, and only the phases are different from each other.

  By doing so, the base station 500 transmits a frame obtained by multiplying the modified scrambling code obtained by modifying the base station scrambling code based on the modified parameter corresponding to the base station scrambling code number of the own apparatus, and Since the modified scrambling codes are composed of the same chip sequence and differ only in phase, the receiving side of this frame pays attention to the phase difference even if the modified scrambling code candidates are formed by focusing on one modification parameter. As a result, the modified scrambling code can be detected. Further, since the success or failure of the cell search can be determined by detecting the modified scrambling code itself, the cell search can be further speeded up as compared with the first embodiment.

  Further, according to Embodiment 3, group pilot symbols formed from a pilot signal and a code group sequence for identifying a group of base station scrambling codes assigned to base station 500 are arranged in mobile station 600. A radio reception unit 210 that receives a frame multiplied by a modified scrambling code formed from the base station scrambling code based on a modified parameter corresponding to the base station scrambling code number, and a base station scrambling code A correspondence table in which code group sequences are associated with deformation parameters, a frame timing / code group detection unit 245 that detects frame timing and code group sequences based on group pilot symbols, and a frame timing / code A modified scrambling code replica is formed based on a modified parameter from a plurality of base station scrambling codes corresponding to the code group sequence detected by the group detection unit 245, and the modified scrambling code is generated using the modified scrambling code replica. A scrambling code replica generation unit 610 and a scrambling code identification unit 620 to detect, and a cell search success / failure determination unit 260 that determines the success or failure of the cell search based on the detection result of the scrambling code identification unit 610 are provided.

  The modified scrambling codes are composed of the same chip sequence and differ only in phase, and the scrambling code identification unit 620 determines one modified parameter from a plurality of base station scrambling codes corresponding to the detected code group sequence. A modified scrambling code candidate is formed based on the above, and the modified scrambling code is detected based on the phase difference of the modified scrambling code candidate from the modified scrambling code.

  In this way, the mobile station 600 transmits a frame in which the base station 500 has multiplied the modified scrambling code obtained by modifying the base station scrambling code based on the modified parameter corresponding to the base station scrambling code number, In addition, since the modified scrambling code is composed of the same chip sequence and is different only in phase, it can be narrowed down to one deformation parameter. Then, a modified scrambling code replica is formed from the one modified parameter, and the scrambling code identification unit 620 determines whether or not the direct cell search has succeeded based on the result of detecting the modified scrambling code using the modified scrambling code replica. Can be determined. As a result, the cell search can be further speeded up as compared with the base station 100 of the first embodiment.

(Embodiment 4)
The first embodiment has been described on the assumption that if the cell search success / failure determination unit 260 determines that the cell search has failed, the cell search immediately returns to the first stage of the cell search. On the other hand, in Embodiment 4, when cell search success / failure determination section 260 determines that the cell search has failed, the correlation value obtained by multiplying the base station scrambling code block and the modified scrambling code. The correlation value having the next magnitude of the correlation value used to identify the base station scrambling code immediately before is the maximum correlation value (the correlation used to identify the base station scrambling code first. It is determined whether it is larger than the threshold value obtained from (value). Then, the return destination is changed between the first stage of cell search and the third stage of cell search according to the determination result.

  As shown in FIG. 13, mobile station 700 of Embodiment 4 has scrambling code identification section 710 and cell search success / failure determination section 720.

  The operation of mobile station 700 having this configuration will be described with reference to FIG.

  Similar to mobile station 200, mobile station 700 first performs operations from step ST1001 to step ST1006.

  As a result of the determination, when the base station scrambling code number received from the scrambling identification unit 710 and the base station scrambling code block identification information are associated with each other in the correspondence table (step ST1006: YES). The cell search success / failure determination unit 720 determines that the cell search is successful, outputs the base station scrambling code received from the scrambling code identification unit 710 to the descrambling unit 265, and, similarly to the mobile station 200, performs step ST1007. And step ST1008 is performed.

  On the other hand, as a result of the determination, when the combination of the base station scrambling code number received from the scrambling identification unit 710 and the base station scrambling code block identification information is not associated in the correspondence table (step ST1006: NO). The cell search success / failure determination unit 260 determines that the cell search has failed, and outputs control information indicating that the cell search has failed to the scrambling code identification unit 710.

  In step ST2001, the scrambling code identification unit 710 receives the control information from the cell search success / failure determination unit 720, and obtains it from the maximum correlation value used to identify the base station scrambling code for the first time in step ST1005. The threshold value is compared with a correlation value having the next magnitude of the correlation value used to identify the base station scrambling code last time.

  As a result of the comparison, a correlation value having the next magnitude of the correlation value used to identify the base station scrambling code last time is obtained from the maximum correlation value used to identify the base station scrambling code for the first time. If it is greater than the threshold value (step ST2001: YES), the scrambling code identification unit 710 returns to step ST1005 again, and next to the correlation value used to identify the base station scrambling code last time. The base station scrambling code that is the basis of the base station scrambling code block corresponding to the “modified scrambling code replica” from which a correlation value having a magnitude is obtained is identified.

  On the other hand, as a result of comparison, the correlation value having the next magnitude of the correlation value used to identify the base station scrambling code last time is the maximum correlation value used to identify the base station scrambling code for the first time. If it is equal to or less than the threshold obtained from step ST2001 (NO), scrambling code identification section 710 outputs control information to that effect to cell search success / failure determination section 720, and cell search success / failure determination section 720 It is determined that the search has failed, a cell search retry signal is output to the reception control unit 205, and the cell search is started again from the first stage.

  As described above, according to the fourth embodiment, mobile station 700 has a group pilot symbol formed from a pilot signal and a code group sequence for identifying a group of base station scrambling codes assigned to base station 100. A radio reception unit 210 configured to receive a frame multiplied by a modified scrambling code formed from the base station scrambling code based on a modified parameter corresponding to a base station scrambling code number and a base station scrambling code; A correspondence table associating a ring code, a code group sequence, and a deformation parameter; a frame timing / code group detection unit 245 that detects a frame timing and a code group sequence based on a group pilot symbol; and a frame timing A modified scrambling code replica is formed from a plurality of base station scrambling codes corresponding to the code group sequence detected by the code group detecting unit 245 based on the modified parameter, and the modified scrambling code replica is generated using the modified scrambling code replica. The scrambling code replica generation unit 255 and the scrambling code identification unit 710 for detecting the cell search, and the cell search success / failure determination unit 720 for determining the success or failure of the cell search based on the detection result of the scrambling code identification unit 710 are provided.

  Then, the cell search success / failure determination unit 720 performs a correlation calculation between each of the formed modified scrambling codes and the group pilot, and detects a modified scrambling code having the largest obtained correlation value.

  Then, when the cell search success / failure determination unit 720 determines that the cell search has failed, the scrambling code identification unit 710 detects the threshold value obtained from the maximum correlation value used to identify the base station scrambling code for the first time. The cell search retry step is changed according to the comparison result between the correlation value having the next magnitude of the correlation value used to identify the base station scrambling code and the previous time.

  By doing so, it is possible to increase the speed of the cell search as compared with the case of retrying from the first stage of the cell search in any case when it is determined that the cell search is unsuccessful.

(Other embodiments)
In the first embodiment, the scrambling code replica generation unit 255 modifies the base station scrambling code corresponding to the code group indicated by the code group sequence identification information using all the modification methods, A modified scrambling code replica was generated. Then, the scrambling code identification unit 250 receives the OFDM symbol including the group pilot located at the head of the frame received from the FFT processing unit 225 for each base station scrambling code block received from the scrambling code replica generation unit 255. Each series (modified scrambling code replica) obtained by repetition is multiplied and correlation calculation is performed. Then, the base station scrambling code that is the basis of the base station scrambling code block corresponding to the “modified scrambling code replica” that provides the largest value among the obtained correlation values was identified. Then, the cell search success / failure determination unit 260 determines whether or not the set of the base station scrambling code number and the base station scrambling code block identification information received from the scrambling identification unit 250 is associated in the correspondence table. Judged.

  However, the present invention is not limited to this, and in particular, when there are two scrambling code sets, the scrambling code replica generation unit 255 has a base corresponding to the code group indicated by the code group sequence identification information. The station scrambling code may be modified using one of the two modification methods to generate a modified scrambling code replica.

  In this case, the scrambling code identification unit 250 receives each OFDM symbol including the group pilot located at the head of the frame received from the FFT processing unit 225 from the scrambling code replica generation unit 255. Each sequence obtained by repetition of the ring code block (that is, a modified scrambling code replica) is multiplied and correlation calculation is performed. Then, the base station scrambling code that is the base of the base station scrambling code block corresponding to the “modified scrambling code replica” that is equal to or greater than the predetermined value among the obtained correlation values is identified. To do. Then, the base station scrambling code block identification information used for identifying the base station scrambling code and the identified base station scrambling code number are output to cell search success / failure determination section 260. Further, the scrambling code identification unit 250 causes the scrambling code replica generation unit 255 to generate the identified base station scrambling code and outputs it to the cell search success / failure determination unit 260.

  The cell search success / failure determination unit 260 determines whether a set of base station scrambling code numbers and base station scrambling code blocks received from the scrambling identification unit 250 is associated in the correspondence table.

  As a result of the determination, if the combination of the base station scrambling code number received from the scrambling identification unit 250 and the base station scrambling code block is associated in the correspondence table, the cell search success / failure determination unit 260 It is determined that the search is successful, and the base station scrambling code received from the scrambling code identification unit 250 is output to the descrambling unit 265.

  On the other hand, the cell search success / failure determination unit 260 determines that the cell search has failed when the correlation value obtained by the scrambling code identification unit 250 does not have a predetermined value or more, and performs the cell search. The cell search retry signal is output to the reception control unit 205 so as to start again from the first stage.

  INDUSTRIAL APPLICABILITY The base station apparatus, mobile station apparatus, and frame transmission method of the present invention are useful as those capable of reducing the time required for cell search and realizing high-speed cell search.

The block diagram which shows the structure of the base station which concerns on Embodiment 1 of this invention. Frame configuration diagram used in Embodiment 1 The figure for demonstrating an example of the formation method of a deformation | transformation scrambling code | cord | chord Block diagram showing a configuration of a mobile station according to the first embodiment The figure which uses for description of operation | movement of the adjacent subcarrier correlation part of FIG. FIG. 4 is another diagram for explaining the operation of the adjacent subcarrier correlation unit in FIG. Flow chart for explaining the operation of the mobile station of FIG. Block diagram showing the configuration of a base station according to Embodiment 2 Block diagram showing a configuration of a mobile station according to Embodiment 2 FIG. 9 is a block diagram showing a configuration of a base station according to Embodiment 3 A diagram for explaining an example of a modified scrambling code used in the third embodiment Block diagram showing a configuration of a mobile station according to Embodiment 3 Block diagram showing a configuration of a mobile station according to Embodiment 4 Flow chart for explaining the operation of the mobile station of FIG. Frame structure diagram used in conventional cell search method Diagram for explaining conventional CPICH creation method Diagram for explaining group pilot creation method Diagram for explaining conventional DPCH creation method Flow chart for explaining operation of mobile station in conventional cell search

Explanation of symbols

100, 300, 500 Base station 105, 280 Encoding unit 110 Pilot signal generation unit 115 Code group sequence generation unit 120 CPICH generation unit 125 Frame configuration unit 130, 310, 510 Scrambling code generation unit 135 Scramble unit 140 OFDM modulation unit 145 GI insertion unit 150, 295 Radio transmission unit 155, 210 Radio reception unit 220 GI removal unit 165 Demodulation unit 170, 270 Decoding unit 200, 400, 600, 700 Mobile station 205 Reception control unit 215 Symbol timing detection unit 225 FFT processing unit 230 Adjacent subcarrier correlation unit 235 Code group sequence replica generation unit 240 Code group sequence correlation unit 245 Frame timing / code group detection unit 250, 420, 620, 710 Scramble Gukodo identification unit 255,410,610 scrambling code replica generator 260,430,720 cell search success determining unit 265 descrambling section 275 CRC check unit 285 modulation unit

Claims (10)

Frame forming means for forming a frame in which a group pilot symbol formed from a pilot signal and a code group sequence for identifying a group of base station scrambling codes assigned to the device is arranged;
Modified scrambling code forming means for forming a modified scrambling code from the base station scrambling code based on a modification parameter corresponding to the number of the base station scrambling code;
Multiplication means for multiplying the formed frame by the modified scrambling code;
Transmitting means for transmitting a frame multiplied by the modified scrambling code;
A base station apparatus comprising:   The base station apparatus according to claim 1, wherein the deformation parameter is different for each code group sequence. The deformation parameter is a base station scrambling code block obtained by dividing the base station scrambling code into a predetermined number,
2. The modified scrambling code forming means performs repetition according to the predetermined number on the base station scrambling code block corresponding to the number of the base station scrambling code to form the modified scrambling code. The base station apparatus as described.   The base station apparatus according to claim 1, wherein the modified scrambling codes are composed of the same chip sequence and differ only in phase. A mobile station device that performs a cell search based on a frame transmitted from a base station device,
In the frame, a group pilot symbol formed from a pilot signal and a code group sequence for identifying a group of base station scrambling codes assigned to the base station apparatus is arranged, and the base station scrambling code number And a modified scrambling code formed from the base station scrambling code based on the corresponding modification parameter, and
A correspondence table in which the base station scrambling code, the code group sequence, and the deformation parameter are associated with each other;
First detection means for detecting frame timing and the code group sequence based on the group pilot symbols;
A modified scrambling code candidate is formed based on the modified parameter from a plurality of base station scrambling codes corresponding to the detected code group sequence, and the modified scrambling code is detected using the modified scrambling code candidate. Two detection means;
Determination means for determining success or failure of the cell search based on a detection result of the second detection means;
A mobile station apparatus comprising:   6. The mobile station according to claim 5, wherein the second detection means performs a correlation operation between each of the formed modified scrambling codes and the group pilot, and detects a modified scrambling code having the largest correlation value. apparatus. A specifying means for specifying the base station scrambling code and the deformation parameter corresponding to the detected modified scrambling code;
6. The mobile station apparatus according to claim 5, wherein the determination unit determines whether or not the cell search is successful based on whether or not the identified base station scrambling code and a modification parameter are associated with each other in the correspondence table. The deformation parameter is different for each code group series,
The second detection means forms a modified scrambling code candidate from a plurality of base station scrambling codes corresponding to the detected code group sequence based on a modification parameter corresponding to the detected code group sequence, Detecting the modified scrambling code using a scrambling code candidate;
The determination means determines that the cell search is successful when the second detection means is able to detect the modified scrambling code, and when the second detection means is unable to detect the modified scrambling code. The mobile station apparatus according to claim 5, wherein it is determined that the cell search has failed. The modified scrambling code is composed of the same chip sequence and is different only in phase from each other.
The second detection means forms a modified scrambling code candidate based on one modification parameter from a plurality of base station scrambling codes corresponding to the detected code group sequence, and the modification of the modified scrambling code candidate The mobile station apparatus according to claim 5, wherein the modified scrambling code is detected based on a phase difference from the scrambling code. Forming a frame in which group pilot symbols formed from a pilot signal and a code group sequence for identifying a group of base station scrambling codes are arranged;
Forming a modified scrambling code from the base station scrambling code based on a modification parameter corresponding to the base station scrambling code number;
Multiplying the formed frame by the modified scrambling code;
Transmitting a frame multiplied by the modified scrambling code;
A frame transmission method comprising:

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