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Correlation detection method, correlation detection apparatus, transmission diversity detection method and transmission diversity detection circuitRelated Patent Categories: Pulse Or Digital Communications, Spread Spectrum, Direct Sequence, Receiver, Having Specific Code SynchronizationCorrelation detection method, correlation detection apparatus, transmission diversity detection method and transmission diversity detection circuit description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20080095217, Correlation detection method, correlation detection apparatus, transmission diversity detection method and transmission diversity detection circuit. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This application is a continuation of pending U.S. patent application Ser. No. 10/312,583, filed Jan. 16, 2003, which is the U.S. National Stage of International Application No. PCT/JP02/03372, filed Apr. 4, 2002, which claims priority of Japanese Patent Application No. 2001-107192, filed on Apr. 5, 2001, the disclosures of which are expressly incorporated herein by reference in their entireties. TECHNICAL FIELD [0002] The present invention relates to correlation detection method in CDMA communication, correlation detection apparatus, method of detection the presence of transmission diversity using synchronization code, and transmission diversity detection circuit. BACKGROUND ART [0003] In CDMA communication, the reception signal is multiplied by spreading code, and the correlation value is obtained after integrating the multiplication results. [0004] In the circuit where it is necessary to carry out correlation detection in a small period of time comparing to a time corresponding to 1 chip (for example, DLL: Delay Locked Loop), there are problems that a circuit configuration becomes complicated, circuit scale becomes large, and power consumption increases with increasing of processing speed. [0005] In addition, there is a case in which transmission side apparatus notifies reception side apparatus whether special processing are carried out or not using a special code. For example, in W-CDMA method applied to IMT2000, the transmission side apparatus notifies reception side apparatus whether STTD transmission diversity processing is carried out or not using synchronization code. [0006] However, an appropriate correlation detection cannot be carried out in the reception side under bad reception environment, and reception side apparatus cannot determine whether the reception signal includes a signal subjected to transmission diversity processing or not. DISCLOSURE OF INVENTION [0007] A first object of the present invention is to carry out correlation detection within a small time unit comparing to the time corresponding to 1 chip while preventing the increase of power consumption or circuit complexity. [0008] Still another object of the present invention is to improve the detection precision when the reception side apparatus detects whether the reception signal includes a signal subjected to STTD transmission diversity processing using a synchronization code while preventing the increase of power consumption or circuit complexity. [0009] In correlation detection method of the present invention, more than two spreading codes are combined, and spreading code of the offset that is smaller than chip interval is generated. Then, the combined spreading code is multiplied by a fixed reception signal, and the correlation value at desired timing is calculated. [0010] Spreading code combining is performed easily using an uncomplicated circuit. Since correlation detection circuit operates within chip clock, the problem of power consumption increasing does not occur. [0011] Furthermore, in transmission diversity detection method of the present invention, it is detected whether an STTD (Space Time block coding based Transmit antenna Diversity) transmission diversity processing is applied or not in the reception signal using a primary synchronization channel (primary SCH) and secondary synchronization channel (secondary SCH). [0012] In addition, even if correlation detection is related to either primary SCH or secondary SCH, the spreading code corresponding to primary SCH and spreading code corresponding to secondary SCH are added. Thus, a combined spreading code is generated, and correlation detection is carried out using such a combined spreading code. [0013] Hence, the precision of (S/N) of the correlation detection which is used for determining the presence of STTD transmission diversity is improved. BRIEF DESCRIPTION OF DRAWINGS [0014] FIG. 1 is a block diagram showing an exemplary configuration of the main part (spreading code generator) of correlation detection apparatus of the present invention; [0015] FIG. 2 is a graph explaining the principle of spreading codes combining in the circuit shown in FIG. 1; [0016] FIG. 3A is an illustration graph to explain the estimation of correlation values; [0017] FIG. 3B is an illustration graph to explain the addition of correlation values; [0018] FIG. 4 is a block diagram showing an exemplary configuration of the main part (spreading code generator) of correlation detection apparatus of the present invention; [0019] FIG. 5 is a block diagram showing an exemplary configuration of a correlation detection apparatus of the present invention; [0020] FIG. 6 is an illustration diagram to explain the operation of a 2/3 value converting circuit and a multiplier in an example of the correlation detection apparatus of the present invention; Continue reading about Correlation detection method, correlation detection apparatus, transmission diversity detection method and transmission diversity detection circuit... Full patent description for Correlation detection method, correlation detection apparatus, transmission diversity detection method and transmission diversity detection circuit Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Correlation detection method, correlation detection apparatus, transmission diversity detection method and transmission diversity detection circuit patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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