JP4794663B2 - Receiving device and scrambling code identification method - Google Patents

Description

The present invention relates to a receiving apparatus and a scrambling code identification method.

  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 cell search, the mobile station selects an optimal cell to be connected when the power is turned on. 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, there is a three-stage initial cell search method in an OFCDM (Orthogonal Frequency and Code Division Multiplexing) method (see, for example, Patent Document 1).

  In the prior art described in Patent Document 1, scrambling codes can be detected at high speed by grouping the scrambling codes into several groups. Specifically, symbol timing based on guard interval correlation is detected in the first stage, and correlation calculation between temporally adjacent OFDM symbols is performed in the second stage to simultaneously detect frame timing and code group, In the stage, a scrambling code is identified by correlation calculation among the scrambling code candidates belonging to the code group detected in the second stage.

  FIG. 18 shows a conventional frame structure of OFCDM. As shown in FIG. 18, the pilot symbols are continuous in the time axis direction at the frame boundary, and the pilot symbol at the end of the frame is multiplied by a code group sequence indicating a group of scrambling codes.

  FIG. 19 shows a conventional second stage process of a cell search performed by a mobile station. The mobile station detects a frame timing and a scrambling code group by performing a correlation operation between a sequence extracted by differential demodulation between adjacent symbols and a code group sequence of all code group candidates. The code group and the frame timing are detected at the same time by detecting the code group sequence and timing at which the maximum correlation value between adjacent pilot symbols is obtained.

JP 2003-244663 A

  However, in the prior art, scrambling code groups are identified using all code group candidates in the second stage, and all scrambling code candidates belonging to the scrambling code group identified in the third stage are used. Since the scrambling code is identified by performing the correlation calculation, there is a problem that the amount of calculation until the scrambling code identification increases.

The present invention has been made in view of this point, and an object of the present invention is to provide a receiving apparatus and a scrambling code identification method capable of reducing cell search processing.

  The base station apparatus according to the first aspect of the present invention starts with a pilot symbol obtained by multiplying a plurality of sequences included in a sequence set corresponding to a code group to which a base station scrambling code assigned to the base station belongs. And a frame forming unit that forms a frame by being arranged at least one of the end and a transmission unit that transmits the formed frame.

  The mobile station apparatus according to the second aspect of the present invention is characterized in that a pilot symbol obtained by multiplying a plurality of sequences included in a sequence set corresponding to a code group to which a base station scrambling code belongs is at least one of a head symbol and a tail symbol. Receiving means for receiving frames arranged in the base station, a correspondence table in which the base station scrambling code and the sequence set are associated with each other, and correlation means for multiplying all candidates of the sequence with the frame to obtain a correlation. Sequence set detection means for detecting a plurality of sequences multiplied by frame timing and the pilot symbols based on the correlation value obtained by the correlation means, and scrambling corresponding to the sequence set including the detected sequence Ring code candidates are identified based on the correspondence table, and the scrambled From the Gukodo candidate employs a configuration having a, a base station scrambling code detection means for detecting the base station scrambling code.

  According to the present invention, cell search processing can be reduced.

The block diagram which shows the structure of the base station apparatus which concerns on Embodiment 1 of this invention. The figure which shows the example of 1 structure of the correspondence table of Embodiment 1. The figure for explanation of the frame configuration of the first embodiment Block diagram showing a configuration of a mobile station apparatus according to Embodiment 1 The figure which uses for description of operation | movement of the adjacent symbol correlation part and code group sequence correlation part of FIG. Flow chart for explaining the operation of the mobile station apparatus of FIG. Block diagram showing configuration of mobile station apparatus according to Embodiment 2 Flow chart for explaining the operation of the mobile station apparatus of FIG. FIG. 9 is a block diagram showing a configuration of a base station apparatus according to Embodiment 3 FIG. 7 is a diagram for explaining a frame configuration according to the third embodiment. Block diagram showing a configuration of a mobile station apparatus according to Embodiment 3 Flow chart for explaining the operation of the mobile station apparatus of FIG. Block diagram showing a configuration of a mobile station apparatus according to Embodiment 4 Block diagram showing configuration of mobile station apparatus according to Embodiment 5 The figure which shows the example of 1 structure of the correspondence table of Embodiment 5. FIG. 14 is a flowchart for explaining the operation of the mobile station apparatus of FIG. Block diagram showing a configuration of a mobile station apparatus according to Embodiment 6 Conventional base station equipment transmission frame format The figure which shows the cell search operation | movement of the conventional mobile station apparatus.

  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 apparatus 100 of Embodiment 1 includes coding section 105, modulation section 110, pilot signal generation section 115, code group sequence generation section 120, code group sequence multiplication section 125, The frame configuration unit 130, the scrambling code generation unit 135, the scrambling unit 140, the IFFT unit 145, the GI insertion unit 150, the radio transmission unit 155, the radio reception unit 160, the GI removal unit 165, and the FFT Unit 170, demodulation unit 175, and decoding unit 180.

  Encoding section 105 receives a transmission signal (DCH or the like), performs predetermined encoding, and outputs the encoded signal to modulation section 110.

  Modulation section 110 receives the encoded signal from encoding section 105, and performs predetermined primary modulation (generally, primary modulation according to the QoS or radio channel state related to the transmission signal) in units of subcarriers. The modulated signal is output to the frame configuration unit 130.

  Pilot signal generation section 115 generates a pilot signal (CPICH) common to all cells, and outputs the generated pilot signal to code group sequence multiplication section 125.

  The code group sequence generation unit 120 receives the scrambling code number from the scrambling code generation unit 135. Then, the code group sequence generation unit 120 selects a code group sequence set to be multiplied by the pilot (CPICH) at the end of the frame with reference to a correspondence table (see FIG. 2) between scrambling code numbers and code group sequence sets. To do. Then, the code group sequence generation unit 120 outputs the selected scrambling code group sequence set to the code group sequence multiplication unit 125. Here, the correspondence table shown in FIG. 2 associates a scrambling code unique to each base station apparatus 100 with a code group sequence set assigned to this scrambling code. This code group sequence set is composed of a plurality of code group sequences (including one type of code group sequence). The code group sequences used in the present embodiment are orthogonal sequences that are orthogonal to each other. Although the code group sequence in the conventional system is used here, the present invention is not limited to this, and any orthogonal sequence that is orthogonal to each other may be used. However, by using an orthogonal sequence already prepared in the conventional system, it is not necessary to prepare an orthogonal sequence for the system of the present invention, so that the burden on system construction can be reduced.

  The code group sequence multiplication unit 125 receives the code group sequence set from the code group sequence generation unit 120. Then, code group sequence multiplication section 125 multiplies all of the code group sequences constituting the code group sequence set by the pilot signal from pilot signal generation section 115. Then, code group sequence multiplication section 125 outputs two sequences of the pilot signal itself and a sequence obtained by multiplying the pilot signal by the code group sequence to frame configuration section 130.

  Frame configuration section 130 receives the modulated signal from modulation section 110, and receives the pilot signal multiplied by the pilot signal and the code group sequence from code group sequence multiplication section 125. Then, frame configuration section 130 forms a frame having a configuration in which a pilot signal multiplied by a code group sequence is arranged at the beginning, and a modulated signal (data) is arranged at the rest. (See FIG. 3). Frame configuration section 130 then outputs an OFDM symbol in units of OFDM symbols that are N subcarrier symbols.

  The scrambling code generation unit 135 generates a scrambling code according to a scrambling code number unique to the base station apparatus 100. Then, scrambling code generation section 135 outputs the scrambling code number to code group sequence generation section 120 and also outputs the generated scrambling code to scrambling section 140.

  The scrambling unit 140 receives the scrambling code from the scrambling code generation unit 135, receives transmission data in units of OFDM symbols from the frame configuration unit 130, and performs scrambling by multiplying the scrambling code for each OFDM symbol. The scrambled transmission data is output to IFFT section 145.

  IFFT section 145 receives the scrambled transmission data from scramble section 140, converts a frequency domain signal into a time domain signal, generates a multicarrier wave signal, and inserts the multicarrier wave signal into a GI (Guard Interval) Output to the unit 150.

  GI insertion section 150 inserts a guard interval for each OFDM symbol, and outputs the signal after the insertion of guard interval to radio transmission section 155.

  Radio transmission section 155 receives the signal after insertion of the guard interval from GI insertion section 150, performs RF processing such as up-conversion, and transmits the result via an antenna.

  Radio receiving section 160 receives a signal from the mobile station apparatus via the antenna, performs RF processing such as down-conversion, and outputs the signal after RF processing to GI removing section 165.

  The GI removal unit 165 receives the RF-processed signal from the wireless reception unit 160, removes the guard interval, and outputs the signal to the FFT unit 170.

  The FFT unit 170 receives the OFDM reception signal after the guard interval removal from the GI removal unit 165, converts the time domain signal into a frequency domain signal, and extracts each subcarrier signal from the multicarrier wave. Then, the signal after FFT is output to demodulation section 175.

  Demodulation section 175 receives the signal after the FFT from FFT section 170 and demodulates each subcarrier. The subcarrier demodulated signal is output to decoding section 180.

  Decoding section 180 receives the demodulated signal from demodulation section 175, performs appropriate error correction decoding, and extracts the received signal.

  As shown in FIG. 4, mobile station apparatus 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 symbols. Correlation section 230, code group sequence replica generation section 235, code group sequence correlation section 240, frame timing / code group detection section 245, scrambling code identification section 250, scrambling code replica generation section 255, desk A rambling unit 260, a decoding unit 265, a CRC check unit 270, an encoding unit 275, a modulation unit 280, a GI insertion unit 285, and a wireless transmission unit 290 are included.

  The reception control unit 205 outputs an output signal from the radio reception unit 210 according to the state of the mobile station device 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. Control the output destination of. Specifically, an output destination command signal is output to the wireless reception unit 210 to control the output destination of the output signal from the wireless reception unit 210. The contents of the output destination command signal are contents indicating that the symbol timing detection unit 215 is the output destination when the state of the mobile station apparatus 200 is the first stage of the initial cell search mode. In some cases, the content indicates that the GI removal unit 220 is the output destination.

  Radio receiving section 210 receives a signal from base station apparatus 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 the mobile station apparatus is in 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. The guard interval correlation is performed on a symbol basis, but the accuracy of symbol timing detection can be improved by averaging the correlation values over one frame. 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.

  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, the FFT processing unit 225 receives an output destination command signal indicating that the adjacent symbol correlation unit 230 is an output destination when the current state of the mobile station apparatus 200 is the second stage of cell search. Then, the signal after FFT processing is output to the adjacent symbol correlation section 230. Further, when the current state of the mobile station apparatus 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, An OFDM symbol including the pilot signal after the FFT processing and arranged at the head of the frame is output to scrambling code identification section 250. Only the scrambling code is applied to the OFDM symbol including the pilot signal arranged at the head of this frame, and the code group sequence is not applied. Also, the FFT processing unit 225 receives an output destination other than the output destination command signal from which the adjacent symbol correlation unit 230 is the output destination and the output destination command signal that the scrambling code identification unit 250 is the output destination from the reception control unit 205. When inputting the command signal, the signal after the FFT processing is output to the descrambling unit 260.

  The adjacent symbol correlation unit 230 receives the signal after the FFT processing from the FFT processing unit 225, and calculates a correlation sequence in which two OFDM symbols that are temporally continuous are correlated (see FIG. 5). The calculation of the correlation sequence is performed over n frames in order to average the correlation values of the correlation sequence and the code group sequence replica later. Then, the calculated correlation sequence 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.

  As shown in FIG. 5, the code group sequence correlation unit 240 receives the correlation sequence calculated by the adjacent symbol correlation unit 230 and the code group sequence from the code group sequence replica generation unit 235, and receives the correlation sequence and all codes. Perform correlation with group series. This correlation calculation is performed for n frames, and an average is obtained for n correlation values obtained from a correlation sequence and a code group sequence calculated from OFDM symbols having the same temporal position in the frame. Code group sequence correlation section 240 then outputs all averaged correlation values to frame timing / code group detection section 245.

  The frame timing / code group detection unit 245 receives the averaged correlation value from the code group sequence correlation unit 240, and detects the maximum correlation value taking the maximum value. Then, the frame timing / code group detection unit 245 stores the timing in the frame from 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 calculates a threshold value used to detect another code group sequence from the value of the maximum correlation value by a predetermined method. Specifically, for example, a value obtained by subtracting a predetermined value X [dB] from the value of the maximum correlation value is set as the threshold value. Then, the frame timing / code group detection unit 245 uses the calculated threshold value to detect the maximum correlation value from the correlation values exceeding the threshold value among the remaining correlation values. Then, except for the stored maximum correlation value, the timing in the frame corresponding to the correlation value having the maximum value and the value exceeding the threshold value and the code group sequence multiplied when obtaining the correlation value are stored. . When there is no correlation value exceeding the threshold other than the maximum correlation value, the code group sequence set multiplied by base station apparatus 100 that has transmitted the frame is composed of one type of code group sequence. At this time, the frame timing / code group detection unit 245 outputs the timing in the frame where the maximum correlation value already stored is obtained to the reception control unit 205 and scrambles the code group sequence corresponding to the maximum correlation value The data is output to the code identification unit 250.

  The frame timing / code group detection unit 245 has a maximum value excluding the stored maximum correlation value and exceeds the threshold when there is a correlation value exceeding the threshold other than the maximum correlation value. It is determined whether the timing in the frame corresponding to the correlation value having a value matches the timing in the frame where the maximum correlation value is obtained. That is, it is determined whether or not the timings corresponding to two correlation values having a large value match. In the present embodiment, since it is assumed that the code group sequence set is composed of two code group sequences, the timing in the frame and the correlation value thereof are set as described above for two correlation values having a large value. Corresponding code group sequence was detected. However, the number of code group sequences constituting the code group sequence set is not limited to two and may be more than two. In that case, the number of correlation values to be detected may be increased according to the number of code group sequences.

  If the timings corresponding to the two correlation values do not match as a result of the determination, the frame timing / code group detection unit 245 determines that the second stage of cell search has failed and fails in the second stage. A second stage failure signal indicating that this has occurred is output to reception control section 205. When the timings corresponding to the two correlation values do not match, it is determined that the second stage of the cell search has failed in the base station apparatus 100 based on the code in the pilot signal arranged in the OFDM symbol at the end of the frame This is because the group sequence sets are multiplied, so that the timing corresponding to the two correlation values needs to match in order for the second stage of the cell search to be successful.

  On the other hand, if the timings corresponding to the two correlation values match as a result of the determination, the frame timing / code group detection unit 245 determines that the detection of the second stage frame timing has succeeded, and detects the detected frame. The timing is output to the reception control unit 205, and the code group sequence identification information (for example, the code group sequence number) for identifying the code group sequence corresponding to the detected two correlation values is output to the scrambling code identification unit 250. . Here, in the present embodiment, the number of scrambling code candidates is already narrowed down to two at the stage of proceeding to the third stage, and the group code identified at the second stage is handled at the stage of proceeding to the third stage. Compared to the conventional cell search method that has been limited to 16 scramble codes, the amount of processing is reduced.

  The scrambling code identification unit 250 identifies the scrambling code corresponding to the code group sequence identification information from the frame timing / code group detection unit 245.

  Specifically, scrambling code identification section 250, when there is only one type of code group sequence identification information from frame timing / code group detection section 245, scrambling code corresponding to this code group sequence identification information Can be uniquely identified, the identification information of the identified scrambling code is output to the scrambling code replica generation unit 255, and the scrambling code replica generated accordingly is output to the descrambling unit 260.

  In addition, when there are two types of code group sequence identification information from the frame timing / code group detection unit 245, the scrambling code identification unit 250 is a scrambling code candidate specified from a combination of these code group sequences. There will be two. Therefore, the identification information of the two scrambling code candidates is output to the scrambling code replica generation unit 255, and the scrambling code replica generated in response thereto is received. Then, the scrambling code identification unit 250 multiplies the scrambling code replica received from the scrambling replica generation unit 255 with the OFDM symbol including the pilot signal located at the head of the frame received from the FFT processing unit 225, and performs correlation calculation. I do. Then, the scrambling code replica from which the largest correlation value is obtained is identified as the scrambling code, and the identified scrambling code is output to the descrambling unit 260.

  There are various methods for identifying the scrambling code in the scrambling code identification unit 250. For example, an OFDM symbol including a pilot signal located at the head of the frame is received from the FFT processing unit 225 over n frames, and each of the n pilot signals is multiplied by a scrambling code replica received from the scrambling replica generation unit 255. Combined correlation calculation is performed and averaged for each. Then, the scrambling code replica from which the largest value among the obtained average values of correlation values is obtained may be identified as the scrambling code.

  The scrambling code replica generation unit 255 generates a scrambling code corresponding to the scrambling code identification information from the scrambling code identification unit 250 and outputs the scrambling code replica to the scrambling code identification unit 250 as a scrambling code replica.

  The descrambling unit 260 receives the signal after the FFT processing from the FFT processing unit 225, multiplies the scrambling code received from the scrambling code identification unit 250, performs descrambling, and decodes the descrambled signal to the decoding unit 265 Output to.

  Decoding section 265 receives the descrambled signal, performs appropriate error correction decoding, and outputs the error correction decoding result to CRC check section 270.

  The CRC check unit 270 performs a CRC error check on the error correction decoding result from the decoding unit 265, 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 270 outputs a CRC error check result to the reception control unit 205 in order to perform 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 275 receives a transmission signal such as DCH, performs predetermined encoding, and outputs the encoded signal to modulation section 280.

  Modulation section 280 receives the encoded signal, performs modulation according to the QoS related to the transmission signal and the radio channel state, and outputs the modulated signal to radio transmission section 290.

  Radio transmission section 290 receives the modulated signal, performs RF processing such as up-conversion, and transmits it through the antenna.

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

  In Step ST1001, the symbol timing detection unit 215 of the mobile station apparatus 200 obtains the guard interval correlation and detects the OFDM symbol timing using the correlation characteristic of the guard interval in the OFDM symbol. This is the first stage of the initial cell search.

  In step ST1002 of the initial cell search second stage, the adjacent symbol correlator 230 receives the FFT-processed signal from the FFT processor 225, and calculates a correlation sequence obtained by correlating two temporally consecutive OFDM symbols. calculate. The correlation sequence is calculated at all symbol timings in the frame.

  In step ST1003, code group sequence correlator 240 receives the correlation sequence calculated by adjacent symbol correlator 230 and the code group sequence from code group sequence replica generator 235, and the correlation sequence, all code group sequences, The correlation calculation is performed. This correlation calculation is performed for all symbol timings of n frames.

  In step ST1004, the code group sequence correlator 240 averages n correlation values obtained from the correlation sequence calculated from the OFDM symbols having the same temporal position in the frame and the code group sequence. That is, since averaging is performed in units of frames, averaged correlation values corresponding to the number of OFDM symbols in one frame are calculated.

  In step ST1005, frame timing / code group detection section 245 receives the averaged correlation value from code group sequence correlation section 240, and detects the maximum correlation value therefrom. Then, the frame timing / code group detection unit 245 stores the symbol timing at which the maximum correlation value is obtained and the code group sequence multiplied when obtaining the maximum correlation value.

  Here, the symbol timing at which the maximum correlation value is obtained and the code group sequence multiplied when obtaining the maximum correlation value are stored. This symbol timing position is a frame timing candidate, and this code group sequence is scrambled. This is to provide a clue for specifying the code. Since there is no correlation between the pilot signal and the transmission data, the correlation value between the OFDM symbol in which the pilot signal is included and the OFDM symbol in which the transmission data is included takes a small value. On the other hand, if a correlation is made between the OFDM symbol including the tail pilot signal and the head pilot signal, and a correlation between the code group sequence multiplied by the tail pilot signal and the same code group sequence, a large peak appears. Therefore, the OFDM symbol timing at which the correlation value between the adjacent OFDM symbol and the code group sequence is maximum is likely to be a frame timing. In addition, the code group sequence giving the maximum correlation value is highly likely to be a code group sequence multiplied by the pilot signal arranged at the end of the frame in the base station apparatus 100 to be accessed.

  In step ST1006, frame timing / code group detection section 245 calculates and sets a threshold value used to detect another code group sequence from the maximum correlation value by a predetermined method. To do. Specifically, for example, a value obtained by subtracting a predetermined value X [dB] from the value of the maximum correlation value is set as the threshold value.

  In step ST1007, frame timing / code group detection section 245 compares the threshold obtained in step ST1006 with the averaged correlation value other than the maximum correlation value.

  As a result of the comparison, when there is a correlation value exceeding the threshold value other than the maximum correlation value (step ST1007: YES), the correlation value is detected (step ST1008).

  In step ST1009, frame timing / code group detection section 245 stores the symbol timing of the correlation value detected in step ST1008 and the code group sequence used when calculating the correlation value.

  In step ST1010, frame timing / code group detection section 245 performs symbol timing (in other words, virtual timing) corresponding to the upper two correlation values (two correlation values from the larger value) stored in steps ST1005 and ST1009. Compare symbol positions in frames).

  As a result of comparison, if both timings are not the same, that is, they do not match (step ST1010: NO), the frame timing / code group detection unit 245 determines that the frame timing identification in the second stage of the initial cell search has failed. Then, by outputting a second stage failure signal indicating that the second stage has failed to the reception control unit 205, the process returns to step ST1001.

  On the other hand, if the timings coincide with each other as a result of the comparison (step ST1010: YES), the frame timing / code group detection unit 245 determines that the detection of the second stage frame timing has succeeded, and the frame timing at this time Thus, the code group series can be identified (step ST1011). Frame timing / code group detection section 245 then outputs code group sequence identification information for identifying the identified code group sequence to scrambling code identification section 250.

  In this way, the success or failure of frame timing detection can be determined based on the difference between the symbol positions of the two correlation values. If it is determined that the frame timing has failed, the subsequent arithmetic processing is stopped at that time. Thus, the initial cell search process can be retried from the first stage. As a result, if the search is unsuccessful, the cell search can be restarted at an early stage, so that the cell search can be speeded up.

  If the correlation value exceeding the threshold is not other than the maximum correlation value as a result of the comparison (step ST1007: NO), the process moves to step ST1011 and the frame timing / code group detection unit 245 stores it in step ST1005. Are identified as frame timing and code group sequences. Frame timing / code group detection section 245 then outputs code group sequence identification information for identifying the identified code group sequence to scrambling code identification section 250.

  Next, the process proceeds to the third stage of the initial cell search, and in step ST1012, a scrambling code candidate corresponding to the code group sequence identification information from the frame timing / code group detection unit 245 is recognized. Replicas of these candidate scrambling codes are sequentially generated, and the maximum correlation value is detected by correlating the pilot signal and the scrambling code replica with the OFDM symbol received signal in which CPICH is multiplexed. Identifying the scrambling code to be generated.

  Finally, whether the identified scrambling code is correct is verified. If it is incorrect, the process returns to step ST1001. For this error verification, for example, the above-described CRC error check can be used.

  In the above description, the transmission / reception frame is configured such that the pilot signal is arranged at the beginning, the pilot signal multiplied by the code group sequence is arranged at the end, and the modulated signal (data) is arranged at the rest. However, the present invention is not limited to this, and conversely, a pilot signal multiplied by a code group sequence at the beginning and a pilot signal at the end may be arranged. Further, the pilot signal may have only one symbol in one frame. In this case, pilot symbols are multiplexed on half of the subcarriers in the one symbol, and pilot and code sequences are on the other half of the subcarriers. Symbols multiplied by and may be multiplexed. In short, it is only necessary that the frame timing can be detected by arranging both pilot signals across the frame boundary, or arranging pilot symbols before or after the frame boundary.

  As described above, according to Embodiment 1, one or a plurality of base stations that are included in a (code group) sequence set corresponding to the code group to which the base station scrambling code assigned to the base station belongs. A frame composing unit 130 that forms a frame by arranging pilot symbols multiplied by the (code group) sequence at at least one of the head and the tail, and a radio transmitting unit 155 that transmits the formed frame. Provided.

  By doing so, the mobile station that receives the frame can detect the frame timing from the position of the pilot symbol included in the frame, and further includes a base station scrambling code and a plurality of (code group) sequences (code Group), the candidates are narrowed down to the number of sequence sets equal to the number of combinations of sequences included in the sequence set by detecting the sequence set multiplied by the pilot symbol. The three-stage scrambling code identification process can be reduced, the cell search process can be reduced, and the base station scrambling code corresponding to this sequence set candidate can be identified at high speed.

  Further, according to Embodiment 1, the mobile station apparatus 200 is multiplied by one or more (code group) sequences included in the (code group) sequence set corresponding to the code group to which the base station scrambling code belongs. A radio reception unit 210 that receives a frame in which pilot symbols are arranged at at least one of a head and a tail, a correspondence table in which the base station scrambling code is associated with the sequence set, and (code group) A code group sequence correlator 240 (adjacent symbol correlator 230) as a correlation means for multiplying all candidates for a sequence by the frame and correlating them, and based on a correlation value obtained by the correlation means, frame timing and One or more (code group) multiplied by the pilot symbol ) A frame timing / code group detection unit 245 for detecting a sequence, a scrambling code candidate corresponding to the sequence set including the detected (code group) sequence is identified based on the correspondence table, and the scrambling And a scrambling code identification unit 250 for detecting the base station scrambling code from among the code candidates.

  In this way, the frame timing can be detected from the position of the pilot symbol included in the received frame, and the base station scrambling code and the sequence set including one or more (code group) sequences are associated with each other. Therefore, by detecting the code group sequence multiplied by the pilot symbol, candidates are narrowed down to the number of spreading code sets corresponding to the number of spreading code combinations included in the spreading code set, thereby reducing the cell search process. The base station scrambling code corresponding to this spreading code set candidate can be identified at high speed.

  The adjacent symbol correlator 230 and the code group sequence correlator 240 as the correlation means sequentially correlate all the (code group) sequence candidates with the correlation sequence between temporally adjacent symbols in the received frame. The frame timing / code group detection unit 245 has the same number as the number of (code group) sequences included in the (code group) sequence set, starting from the one having a larger value than the correlation value obtained by the correlation means. The symbol timing in the (virtual) frame from which the specified correlation value is obtained and the (code group) sequence multiplied when obtaining the specified correlation value are multiplied by the frame timing and the pilot symbol. Detect as (code group) series.

  In this way, a correlation sequence between temporally adjacent symbols in a received frame is correlated by sequentially multiplying all candidates of the (code group) sequence, and frame timing and sequence are detected using this correlation value. By doing so, the influence of the phase noise added to the received frame in the propagation path or the like can be reduced, so that the frame timing and sequence can be detected more accurately.

(Embodiment 2)
In Embodiment 1, the correlation value obtained by performing the correlation operation for each code group sequence on the correlation sequence of adjacent OFDM symbols is averaged over n frames for each code group sequence, and then the top 1 One or two correlation values were detected by threshold determination, and a code group sequence multiplied when obtaining the detected correlation value was detected to identify the code group sequence used by the base station. On the other hand, in Embodiment 2, the correlation value obtained by performing the correlation operation for each code group sequence on the correlation sequence of the adjacent OFDM symbol is added for each code group sequence set. After the summed correlation values are averaged over n / 2 frames, the code group sequence set multiplied to obtain the maximum correlation value among the averaged correlation values is identified. By doing this, the number of objects to be subjected to the averaging process over n frames, which has been performed in the first embodiment, is halved, so that a faster initial cell search can be performed. In addition, since the S / N ratio of the OFDM reception symbol can be increased by performing the addition process, the reliability is as high as that of the first embodiment even if the number of frames to be averaged is reduced to about half. A value can be obtained, and a faster and more reliable initial cell search can be realized.

  As shown in FIG. 7, mobile station apparatus 300 according to Embodiment 2 includes code group sequence correlation section 310 and frame timing / code group detection section 320.

  The code group sequence correlation unit 310 receives the correlation sequence calculated by the adjacent symbol 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. Do. Then, the code group sequence correlation unit 310 adds the correlation values obtained by the correlation calculation by combinations corresponding to the code group sequence set. Then, the addition correlation value obtained by the addition is averaged for each code group sequence set over n / 2 frames. Code group sequence correlation section 310 then outputs all of the averaged addition correlation values to frame timing / code group detection section 320.

  Frame timing / code group detection section 320 receives the averaged correlation value from code group sequence correlation section 310 and detects the maximum correlation value that takes the maximum value. Then, the frame timing / code group detection unit 320 identifies the timing (position) of the symbol from which the maximum added correlation value is obtained and the code group sequence set multiplied when obtaining the maximum added correlation value.

  Frame timing / code group detection section 320 then outputs information identifying the identified code group sequence set to scrambling code identification section 250. The information for identifying the code group sequence set may be, for example, code group sequence identification information constituting the code group sequence set, or a scrambling code number corresponding to the code group sequence set. Good.

  Next, the operation of mobile station apparatus 300 having the above configuration will be described with reference to FIG.

  In step ST1003, code group sequence correlator 310 receives the correlation sequence calculated by adjacent symbol correlator 230 and the code group sequence from code group sequence replica generator 235, and receives the correlation sequence and all code group sequences. The correlation calculation is performed.

  In step ST2001, code group sequence correlation section 310 adds the correlation values obtained by the correlation calculation for each symbol by a combination corresponding to the code group sequence set.

  In step ST2002, code group sequence correlation section 310 averages the added correlation value obtained by the addition for each symbol over n / 2 frames. Code group sequence correlation section 310 then outputs all of the averaged addition correlation values to frame timing / code group detection section 320.

  In step ST2003, frame timing / code group detection section 320 receives the averaged addition correlation value from code group sequence correlation section 310, and detects the maximum addition correlation value taking the maximum value.

  In step ST2004, frame timing / code group detection section 320 identifies the symbol timing at which the maximum added correlation value is obtained and the code group sequence set multiplied when obtaining the maximum added correlation value.

  Frame timing / code group detection section 320 then outputs information identifying the identified code group sequence set to scrambling code identification section 250.

  Thus, according to Embodiment 2, the pilot symbol obtained by multiplying the mobile station apparatus 300 by a plurality of (code group) sequences included in the (code group) sequence set corresponding to the base station scrambling code is the first and A radio reception unit 210 that receives a frame arranged at at least one of the tail, a correspondence table (see FIG. 2) in which the base station scrambling code and the (code group) sequence set are associated, An adjacent symbol correlator 230 and a code group sequence correlator 310 for calculating a correlation value by sequentially multiplying all of the (code group) sequence candidates by a correlation sequence between temporally adjacent symbols in a frame; and the correlation Multiply the frame timing and the pilot symbol based on the value A frame timing / code group detection unit 320 for detecting a (code group) sequence, and scrambling code candidates corresponding to the (code group) sequence set including the detected (code group) sequence from the correspondence table A scrambling code identification unit 250 is provided for detecting the base station scrambling code from the scrambling code candidates.

  In this way, the SN ratio of the received symbol can be increased by performing the correlation value addition process within one symbol, so the number of averaged frames is reduced to about half when averaging is performed over a plurality of frames. However, a highly reliable value can be obtained, and a faster cell search can be realized.

(Embodiment 3)
In Embodiment 1, base station apparatus 100 multiplies all code group sequences constituting a code group sequence set for all subcarriers in the OFDM symbol at the end of the frame. On the other hand, in Embodiment 3, the base station apparatus divides the subcarrier in the OFDM symbol at the end of the frame into a plurality of subcarrier blocks, and a plurality of code groups corresponding to the code group sequence set for each subcarrier block The code group series constituting the series are respectively multiplied.

  As shown in FIG. 9, base station apparatus 400 of Embodiment 3 has code group sequence multiplication section 410 and frame configuration section 420.

  The code group sequence multiplication unit 410 receives the code group sequence set from the code group sequence generation unit 120. Then, code group sequence multiplication section 410 multiplies each of the code group sequences constituting the code group sequence set by the pilot signal from pilot signal generation section 115, and as a result, the pilot signal multiplied by each code group sequence Is generated. Then, code group sequence multiplication section 410 outputs a plurality of sequences of the pilot signal itself and a sequence obtained by multiplying the pilot signal by each code group sequence to frame configuration section 420.

  Frame configuration section 420 receives a modulated signal from modulation section 110, and receives a pilot signal multiplied by a pilot signal and a code group sequence from code group sequence multiplication section 410. Then, frame configuration section 420 forms a frame having a configuration in which a pilot signal multiplied by a code group sequence is arranged at the head, and a modulated signal (data) is arranged at the rest. (See FIG. 10). Further, in the frame formed by this frame configuration section 420, the subcarriers in the OFDM symbol in which the last pilot signal is arranged are divided into subcarrier blocks, and codes constituting a code group sequence set for each subcarrier block Each group series is multiplied. Specifically, in FIG. 10, it is divided into two subcarrier blocks, a low frequency side subcarrier block 1 and a high frequency side subcarrier block 2, for example, a code group corresponding to a scrambling code number C2. CG1 which is a code group sequence constituting the sequence set is multiplied by subcarrier block 1, and CG2 is multiplied by subcarrier block 2.

  In FIG. 10, in order to simplify the description, the code group sequence set is divided into two subcarrier blocks corresponding to the number of code group sequences included in the code group sequence set. However, the present invention is not limited to this and may be divided into two subcarrier groups. That is, the subcarriers to which the code group sequences are multiplied do not have to be subcarrier blocks that are continuous in the frequency direction, and may be skipped. In this specification, the subcarrier block is assumed to be a form of a subcarrier group. When the code group sequence set corresponds to n code group sequences, the number of divided subcarrier groups in FIG.

  Frame configuration section 420 then outputs an OFDM symbol in units of OFDM symbols that are N subcarrier symbols.

  As shown in FIG. 11, mobile station apparatus 500 according to Embodiment 3 includes adjacent symbol correlation section 510, code group sequence correlation section 520, and frame timing / code group detection section 530.

  Adjacent symbol correlation section 510 receives the FFT-processed signal from FFT processing section 225, and calculates a correlation sequence in which two OFDM symbols that are temporally continuous are correlated. The calculation of the correlation sequence is performed over n frames for later averaging. Then, the calculated correlation sequence is output to code group sequence correlation section 520.

  The code group sequence correlation unit 520 receives the correlation sequence calculated by the adjacent symbol correlation unit 510 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. Do. However, here, unlike Embodiment 1, correlation calculation is performed for each subcarrier block. That is, the code group sequence length in the third embodiment is half that in the first embodiment.

  This correlation calculation is performed for n frames, and the code group sequence correlator 520 averages n correlation values obtained from the correlation sequence calculated from the OFDM symbol having the same temporal position in the frame and the code group sequence. . Then, code group sequence correlation section 520 outputs all correlation values averaged for each subcarrier block to frame timing / code group detection section 530.

  Frame timing / code group detection section 530 receives a correlation value averaged for each subcarrier block from code group sequence correlation section 520, and detects a maximum correlation value that takes the maximum value for each subcarrier block. Frame timing / code group detection section 530 stores the symbol timing (in the virtual frame) from which the maximum correlation value is obtained and the code group sequence multiplied when obtaining the maximum correlation value.

  Also, frame timing / code group detection section 530 determines whether or not the timing (in the frame) at which the maximum correlation value detected for each subcarrier block is obtained matches.

  As a result of the determination, if the timings in the frame where the maximum correlation value detected for each subcarrier block is obtained do not match, the frame timing / code group detection unit 530 failed to detect the frame timing in the second stage of the initial cell search. The second stage failure signal indicating that the second stage has failed is output to the reception control unit 205.

  On the other hand, if the determination shows that the detected maximum correlation value for each subcarrier block matches the timing (in the frame), the frame timing / code group detection unit 530 detects the second stage frame timing. It is determined that it has succeeded, and the detected frame timing is output to the reception control unit 205, and code group sequence identification information for identifying the detected code group sequence is output to the scrambling code identification unit 250.

  Next, the operation of mobile station apparatus 500 having the above configuration will be described with reference to FIG.

  In step ST3001, code group sequence correlation section 520 receives the correlation sequence calculated by adjacent symbol correlation section 510 and the code group sequence from code group sequence replica generation section 235, and receives the correlation sequence and all code group sequences. The correlation calculation is performed. However, here, the correlation calculation is performed for each subcarrier block.

  In step ST3002, code group sequence correlation section 520 averages n correlation values obtained from the correlation sequence and code group sequence calculated from OFDM symbols having the same temporal position in the frame for each identical subcarrier block. .

  In step ST3003, frame timing / code group detection section 530 receives the correlation value averaged for each subcarrier block from code group sequence correlation section 520, and detects the maximum correlation value for each subcarrier block.

  In step ST3004, frame timing / code group detection section 530 determines whether or not the timing at which the maximum correlation value detected for each subcarrier block is obtained matches.

  As a result of the determination, if the timing at which the maximum correlation value detected for each subcarrier block is obtained does not match (step ST3004: NO), the frame timing / code group detection unit 530 performs the frame timing of the initial cell search second stage. By determining that the detection has failed and outputting a second stage failure signal indicating that the second stage has failed to the reception control unit 205, the process returns to step ST1001.

  On the other hand, as a result of the determination, when the timing at which the maximum correlation value detected for each subcarrier block is obtained matches (step ST3004: YES), frame timing / code group detection section 530 determines the second stage frame timing. It is determined that the detection is successful, and at this time, the frame timing and the code group sequence can be identified (step ST1011). Frame timing / code group detection section 530 outputs the detected frame timing to reception control section 205 and also outputs code group sequence identification information for identifying the detected code group series to scrambling code identification section 250.

  In the above description, the description has been made on the assumption that there is orthogonality between the scrambling code and the code group sequence constituting the code group sequence set. However, in the present embodiment, the code group sequence multiplied for each subcarrier block is different, and therefore it is not always necessary to have orthogonality between code group sequences.

  As described above, according to Embodiment 3, a plurality of subcarriers are divided into a plurality of groups in base station apparatus 400, and each group corresponds to a base station scrambling code assigned to the own apparatus ( Code group) a frame configuration unit 420 that forms a frame in which pilot symbols multiplied by (code group) sequences one by one included in a sequence set are arranged at at least one of the beginning and the end, and the formed frame And a wireless transmission unit 155 for transmitting.

  The mobile station that receives the frame can detect the frame timing from the position of a pilot symbol included in the frame, and further includes a base station scrambling code and a (code group) sequence set including a plurality of (code group) sequences; By detecting the (code group) sequence multiplied by each subcarrier block of the pilot symbol, the combination of the (code group) sequence included in the (code group) sequence set at most is detected. Since the number of scrambling code candidates is narrowed down to the number, the cell search process can be reduced, and the base station scrambling code corresponding to this spreading code set candidate can be specified at high speed.

  Also, according to Embodiment 3, mobile station apparatus 500 includes a plurality of subcarriers divided into a plurality of groups and included in a sequence set corresponding to a base station scrambling code for each subcarrier group (code group). A radio receiving unit 210 that receives a frame in which pilot symbols multiplied by one (code group) sequence are arranged at the head and / or at the end, the base station scrambling code, and the (code group) Code group sequence correlation as correlation means for calculating a correlation sequence by multiplying a correspondence table (see FIG. 2) associated with a sequence set and all the (code group) sequence candidates sequentially for each subcarrier group Unit 520 (adjacent symbol correlation unit 510) and the correlation means A frame timing / code group detection unit 530 that detects a frame code and a (code group) sequence multiplied by the pilot symbol for each subcarrier group based on the function value; and the detected (code group) sequence A scrambling code identifying unit 250 is provided that identifies scrambling code candidates corresponding to combinations from the correspondence table and detects the base station scrambling code from the scrambling code candidates.

  By doing this, it is possible to detect the frame timing from the position of the pilot symbol included in the received frame, and further, since the base station scrambling code is related as a combination of a plurality of (code groups) sequences, the pilot symbol By detecting the (code group) sequence multiplied by each subcarrier group in (code group), the number of combinations of (code group) sequences included in the (code group) sequence set is considered as a candidate in the (code group) sequence set. The base station scrambling code corresponding to this (code group) sequence set candidate can be identified at high speed, and the initial cell search process can be reduced.

  Adjacent symbol correlator 510 and code group sequence correlator 520 serving as the correlating means assign all the candidates for (code group) sequences for each subcarrier group with respect to correlation values between temporally adjacent symbols in the frame The frame timing / code group detection unit 530 detects the maximum correlation value in each subcarrier group from the correlation value obtained by the correlation means, and obtains the detected maximum correlation value. The code group sequence multiplied when obtaining the detected maximum correlation value of each subcarrier group is detected as a (code group) sequence multiplied for each subcarrier group of the frame timing and the pilot symbol.

(Embodiment 4)
In Embodiment 3, after the correlation value obtained by performing the correlation operation for each code group sequence on the correlation value of the adjacent OFDM symbol is averaged over n frames for each code group sequence and subcarrier block, The code group series multiplied when obtaining the maximum correlation value for each subcarrier block was identified. On the other hand, in Embodiment 4, the correlation value obtained by performing the correlation operation for each code group sequence and each subcarrier block on the correlation sequence of the adjacent OFDM symbol is obtained for each code group sequence set. After adding and averaging the added correlation values over n / 2 frames, the code group sequence set multiplied to obtain the maximum correlation value among the averaged correlation values is identified. By doing so, since the S / N ratio of the correlation value is improved within one OFDM symbol, the number of objects to be averaged over n frames is halved, so that a faster cell search is possible. In addition, since the SN ratio of the OFDM received symbol can be increased by performing the addition process, the reliability is as high as that of the third embodiment even if the number of frames to be averaged is reduced to about half. A value can be obtained, and a faster cell search can be realized.

  As shown in FIG. 13, mobile station apparatus 600 according to Embodiment 4 includes code group sequence correlation section 610 and frame timing / code group detection section 620.

  The code group sequence correlation unit 610 receives the correlation sequence calculated by the adjacent symbol correlation unit 510 and the code group sequence from the code group sequence replica generation unit 235, and performs correlation calculation between the correlation sequence and all code group sequences. Do. However, here, for each subcarrier block, a correlation sequence is calculated, and a correlation calculation between the correlation sequence and all code group sequences is performed.

  Then, the code group sequence correlation unit 610 adds the correlation values obtained by the correlation calculation by combinations corresponding to the code group sequence set. Then, the addition correlation value obtained by the addition is averaged for each code group sequence set over n / 2 frames. Code group sequence correlation section 610 then outputs all the averaged correlation values to frame timing / code group detection section 620.

  Frame timing / code group detection section 620 receives the averaged addition correlation value from code group sequence correlation section 610 and detects the maximum addition correlation value. Then, frame timing / code group detection section 620 identifies the timing at which the maximum addition correlation value is obtained and the code group sequence set that has been multiplied when obtaining the maximum addition correlation value.

  Frame timing / code group detection section 620 then outputs information identifying the identified code group sequence set to scrambling code identification section 250. The information for identifying the code group sequence set may be, for example, code group sequence identification information constituting the code group sequence set, or a scrambling code number corresponding to the code group sequence set. Good.

  In the present embodiment, it is basically necessary to specify a code group sequence from an addition correlation value obtained by multiplying a plurality of code group sequences, so that orthogonality is maintained between code group sequences. There is a need.

  Thus, according to Embodiment 4, in mobile station apparatus 600, a plurality of subcarriers are divided into a plurality of groups, and each subcarrier group corresponds to a base station scrambling code (code group) sequence set. A radio reception unit 210 that receives a frame in which pilot symbols multiplied by one (code group) sequence are included in at least one of the head and the tail, the base station scrambling code, and the (code A correspondence table (see FIG. 2) in which a (group) sequence set is associated, and all the (code group) sequence candidates for each subcarrier group with respect to a correlation sequence between temporally adjacent symbols in the frame And correlate to (code group) sequence set And the adjacent symbol correlation unit 510 and code group sequence correlation unit 610 as correlation means for calculating an addition correlation value by adding together, and specifying the maximum addition correlation value from the addition correlation value, and specifying the specified maximum addition correlation value The frame timing for detecting the timing in the frame from which the signal is obtained and the (code group) sequence multiplied when obtaining the specified maximum added correlation value as the (code group) sequence multiplied by the frame timing and the pilot symbol / Code group detection unit 620 and scrambling code candidates corresponding to the (code group) sequence set including the detected (code group) sequence are limited from the correspondence table, and from among the scrambling code candidates Base station scramble A scrambling code identification section 250 for detecting the Gukodo, and the provided.

  In this way, since the SN ratio of the received symbol can be increased by performing the correlation value addition process, the reliability can be reduced even if the number of average frames is reduced to about half when performing the average process over a plurality of frames. Can be obtained, and a faster cell search can be realized.

(Embodiment 5)
In the third embodiment, after the correlation value obtained by performing the correlation operation for each code group sequence on the correlation sequence of adjacent OFDM symbols is averaged over n frames for each code group sequence and subcarrier block, The code group series multiplied when obtaining the maximum correlation value for each subcarrier block was identified. On the other hand, in the fifth embodiment, the scrambling code can be specified when the code group sequence for each subcarrier block can be specified by further associating the subcarrier block with the code group sequence. That is, the third stage of cell search can be omitted.

  As shown in FIG. 14, mobile station apparatus 700 of Embodiment 5 has a frame timing / code group detection unit 710 and a scrambling code identification unit 720.

  Frame timing / code group detection section 710 receives a correlation value averaged for each subcarrier block from code group sequence correlation section 520, and detects a maximum correlation value that takes the maximum value for each subcarrier block. Frame timing / code group detection section 710 stores the timing in the frame at which the maximum correlation value is obtained and the code group sequence multiplied when obtaining the maximum correlation value.

  In addition, frame timing / code group detection section 710 determines whether or not the timings in the frame from which the maximum correlation value detected for each subcarrier block is obtained match.

  As a result of the determination, if the timings in the frame where the maximum correlation value detected for each subcarrier block is obtained do not match, the frame timing / code group detection unit 710 has failed in the frame timing identification in the second stage of the initial cell search. The second stage failure signal indicating that the second stage has failed is output to the reception control unit 205.

  On the other hand, as a result of the determination, if the timings in the frames where the maximum correlation value detected for each subcarrier block is obtained match, the frame timing / code group detection unit 710 has successfully detected the second stage frame timing. The detected frame timing is output to the reception control unit 205, and the code group sequence identification information for identifying the detected code group sequence is associated with the identification information of the subcarrier block from which the code group sequence is detected. Then, it is output to the scrambling code identification unit 720.

  The scrambling code identification unit 720 identifies and identifies the scrambling code corresponding to the code group sequence identification information and the subcarrier block identification information from the frame timing / code group detection unit 710 with reference to the table shown in FIG. The scrambling code is generated by the scrambling code replica generation unit 255 and output to the descrambling unit 260. In the present embodiment, the base station device multiplies the code group sequence set, that is, the code group sequence defined for each subcarrier block, from the scrambling code number of the base station itself according to the table of FIG.

  Next, the operation of mobile station apparatus 700 having the above configuration will be described with reference to FIG.

  If the timings in the frame where the maximum correlation value detected for each subcarrier block is obtained match (step ST3004: YES), in step ST4001, frame timing / code group detection section 710 determines the frame timing of the second stage. The scrambling code identification unit 720 determines that the detection has succeeded and identifies the frame timing. The scrambling code identification unit 720 also includes a scrambling code corresponding to the code group sequence identification information and the subcarrier block identification information from the frame timing / code group detection unit 710. Is identified (identified) with reference to the table.

  In the above description, the description has been made on the assumption that there is orthogonality between the scrambling code and the code group sequence constituting the code group sequence set. However, in the present embodiment, since the subcarrier blocks are already orthogonal, it is not always necessary to have orthogonality between code group sequences.

  Thus, according to Embodiment 5, in mobile station apparatus 700, a plurality of subcarriers are divided into a plurality of groups, and each subcarrier group corresponds to a base station scrambling code (code group) sequence set. A radio reception unit 210 that receives a frame in which pilot symbols multiplied by one (code group) sequence are included in at least one of the head and the tail, the base station scrambling code, and the (code A correspondence table (see FIG. 15) in which the identification information of the subcarrier group obtained by multiplying the (group) sequence set and the (code group) sequence included in the (code group) sequence set is associated with all (code) Group) series is sequentially multiplied for each subcarrier group. A code group sequence correlator 520 as a correlation means for taking a correlation, and a (code group) sequence multiplied by the frame timing and the pilot symbol based on the correlation value for each subcarrier group obtained by the correlation means Frame timing / code for detecting and identifying the base station scrambling code using the correspondence table based on the detected (code group) sequence and the identification information of the group from which the (code group) sequence is detected A group detection unit 710 and a scrambling code identification unit 720 are provided.

  By doing so, since the subcarrier block and the code group sequence are further associated with each other as compared with FIG. 2, the scrambling code can also be identified when the code group sequence to be multiplied for each subcarrier block can be identified. As a result, since the step corresponding to the third stage in the conventional cell search can be omitted, the initial cell search process can be reduced and a faster cell search can be realized.

(Embodiment 6)
In Embodiment 5, after the correlation value obtained by performing the correlation calculation for each code group sequence on the correlation value of the adjacent OFDM symbol is averaged over n frames for each code group sequence and subcarrier block, The code group series multiplied when obtaining the maximum correlation value for each subcarrier block was identified. On the other hand, in Embodiment 6, the correlation value obtained by performing the correlation operation for each code group sequence and each subcarrier block on the correlation sequence of the adjacent OFDM symbol is used as the subcarrier block and the code group sequence. In order to obtain the maximum correlation value among the averaged correlation values after averaging the summed correlation values over n / 2 frames. Identify the crossed code group sequence set. By doing so, since the S / N ratio of the correlation value is improved within one OFDM symbol, the number of objects to be averaged over n frames is halved, so that a faster cell search is possible. In addition, since the SN ratio of the OFDM reception symbol can be increased by performing the addition process, even if the number of frames to be averaged is reduced to about half, the reliability is as high as that of the fifth embodiment. A value can be obtained, and a faster cell search can be realized. Note that “adding for each code group sequence set in consideration of the correspondence between subcarrier blocks and code group sequences” means that the code group sequence and sub group are the same even if the combination of code group sequences included in the code group sequence set is the same. If the correspondence with the carrier block is different, it means that the addition is performed by treating it as another code group sequence set.

  As shown in FIG. 17, mobile station apparatus 800 according to Embodiment 6 includes code group sequence correlation section 810 and frame timing / code group detection section 820.

  The code group sequence correlation unit 810 receives the correlation sequence calculated by the adjacent symbol correlation unit 510 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. Do. However, here, for each subcarrier block, a correlation sequence is calculated, and a correlation calculation between the correlation sequence and all code group sequences is performed.

  Then, the code group sequence correlation unit 810 adds the correlation value obtained by the correlation calculation for each code group sequence set in consideration of the correspondence between the subcarrier block and the code group sequence. Then, the addition correlation value obtained by the addition is averaged for each code group sequence set in consideration of the correspondence between the subcarrier block and the code group sequence over n / 2 frames. Code group sequence correlation section 810 then outputs all of the averaged correlation values to frame timing / code group detection section 820.

  The frame timing / code group detection unit 820 receives the averaged addition correlation value from the code group sequence correlation unit 810 and detects the maximum addition correlation value. Frame timing / code group detection section 820 takes into account the timing at which the maximum added correlation value is obtained and the code group sequence set multiplied when obtaining the maximum added correlation value (corresponding to the correspondence between subcarrier blocks and code group sequences). Identified).

  Frame timing / code group detection section 820 associates the identified code group series identification information with the identified code group series and the identification information of the corresponding subcarrier block, and outputs them to scrambling code identification section 720. To do.

  In the present embodiment, it is basically necessary to specify a code group sequence from an addition correlation value obtained by multiplying a plurality of code group sequences, so that orthogonality is maintained between code group sequences. There is a need.

  Thus, according to Embodiment 6, mobile station apparatus 800 divides a plurality of subcarriers into a plurality of groups, and sets a (code group) sequence set corresponding to the base station scrambling code for each subcarrier group. A radio reception unit 210 that receives a frame in which pilot symbols multiplied by one (code group) sequence are included in at least one of the head and the tail, the base station scrambling code, and the (code A correspondence table (see FIG. 15) in which the identification information of the subcarrier group obtained by multiplying the (group) sequence set and the (code group) sequence included in the (code group) sequence set is associated, and the (code group) ) All the candidates for the sequence are temporally adjacent symbols in the frame The correlation sequence is multiplied by each subcarrier group to obtain a correlation, and is added for each (code group) sequence set specified by the correspondence between the subcarrier group and the (code group) sequence. The adjacent symbol correlation unit 510 and code group sequence correlation unit 810 as correlation means for calculating the addition correlation value, the maximum addition correlation value specified from the addition correlation value, and the frame from which the specified maximum addition correlation value was obtained And a frame timing / code group detection unit 820 for identifying the (code group) sequence set from which the specified maximum added correlation value is obtained, and the base station corresponding to the identified (code group) sequence set Scramble to identify the scrambling code from the correspondence table And Gukodo identification unit 720, and the provided.

  In this way, since the SN ratio of the received symbol can be increased by performing the correlation value addition process, the reliability can be reduced even if the number of average frames is reduced to about half when performing the average process over a plurality of frames. Can be obtained, and a faster cell search can be realized.

(Other embodiments)
In Embodiments 1 to 4, when the base station scrambling code is identified in the third stage of the initial cell search, the group code sequence is not multiplied and only the base station scrambling code is multiplied. The explanation was made assuming that the pilot symbols are used. However, the present invention is not limited to this, and a pilot symbol multiplied by a group code sequence (in each embodiment, a pilot symbol arranged at the head of a frame) can be used.

  As a specific example, a case where the present invention is applied to the first embodiment will be described with reference to FIG.

  In this case, if the current state of the mobile station apparatus 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. The input OFDM symbol including the pilot signal after FFT processing and including the pilot signal arranged at the end of the frame is output to scrambling code identification section 250.

  The scrambling code identification unit 250 multiplies the complex conjugate of the code group sequence identified in the second stage, and extracts a pilot signal that is multiplied only by the scrambling code.

  The present invention is useful as one that can reduce cell search processing.

100, 400 Base station apparatus 105, 275 Encoding unit 110, 280 Modulation unit 115 Pilot signal generation unit 120 Code group sequence generation unit 125, 410 Code group sequence multiplication unit 130, 420 Frame configuration unit 135 Scrambling code generation unit 140 Scramble Unit 145 IFFT unit 150, 285 GI insertion unit 155, 290 wireless transmission unit 160, 210 wireless reception unit 165, 220 GI removal unit 170, 225 FFT unit 175 demodulation unit 180, 265 decoding unit 200, 300, 500, 600, 700 Mobile station apparatus 205 Reception control unit 215 Symbol timing detection unit 230, 510 Adjacent symbol correlation unit 235 Code group sequence replica generation unit 240, 310, 520, 610, 810 Code group sequence correlation unit 2 45, 320, 530, 620, 710, 820 Frame timing / code group detection unit 250, 720 Scrambling code identification unit 255 Scrambling code replica generation unit 260 Descrambling unit 270 CRC check unit

Claims (6)

First information and second information used in combination to identify a scrambling code unique to a cell, and the combination is a one-to-one correspondence with a scrambling code group composed of scrambling code candidates. and the corresponding receiving means for simultaneously receiving said first information and said second information from the different sub-carrier,
A scrambling code group is identified using a combination of the first information and the second information, and a scrambling unique to a cell from among the plurality of scrambling codes included in the identified scrambling code group An identification means for identifying the code;
A receiving apparatus comprising: The receiving means receives the first information from one or more subcarriers among a plurality of subcarriers included in a first subcarrier group, and receives the second information as the first subcarrier group. Are received from one or more subcarriers among a plurality of subcarriers included in different second subcarrier groups,
The receiving device according to claim 1. A plurality of subcarriers included in the first subcarrier group are located in a jump; a plurality of subcarriers included in the second subcarrier group are located in a jump;
The receiving device according to claim 2. First information and second information used in combination to identify a scrambling code unique to a cell, and the combination is a one-to-one correspondence with a scrambling code group composed of scrambling code candidates. corresponding, simultaneously received from said first information and said second information and different sub-carriers,
A scrambling code group is identified using a combination of the first information and the second information, and a scrambling unique to a cell from among the plurality of scrambling codes included in the identified scrambling code group Identify the code,
Scrambling code identification method. The first information is received from one or more subcarriers among a plurality of subcarriers included in the first subcarrier group, and the second information is different from the first subcarrier group. Receiving from one or more subcarriers among a plurality of subcarriers included in the subcarrier group;
The scrambling code identification method according to claim 4. A plurality of subcarriers included in the first subcarrier group are located in a jump; a plurality of subcarriers included in the second subcarrier group are located in a jump;
The scrambling code identification method according to claim 5.

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