Code synchronous timing determining method upon information reception in CDMA system, determining apparatus, and CDMA receiving apparatus

A code synchronous timing determining method comprising:

• acquiring plural correlation values showing correlation between a code assigned in a specified channel and a code included in a CDMA reception signal together with the time data showing the timing of obtaining the correlation values;
• storing the acquired plural correlation values in association with the corresponding time data;
• detecting, at a timing of notice, a timing having a largest correlation value in the stored plural correlation values within a predetermined time width;
• registering the largest timing detected at the timing of notice as the maximal timing;
• comparing each correlation value stored in the forward and backward directions from the maximal timing with a predetermined value;
• registering a timing when the associated correlation value is detected to be less than a minimum correlation value as the minimal timing;
• extracting at least one high correlation value from the correlation values obtained in the every specified time interval from the maximal timing till the minimal timing;
• and
• registering a timing data corresponding to the extracted high correlation value as candidate timing data for code synchronism.

A code synchronous timing determining apparatus comprising:

• a correlator configured to acquire correlation values of a code included in a received CDMA signal and an internal code provided in the apparatus at plural timings in each of a plural given time widths included in a given period;
• a storage circuit configured to store the correlation values corresponding to the plural timings;
• a first registering unit configured to retrieve at least one timing having a maximal value among stored plural correlation values and to register the one timing as a maximal timing;
• a second registering unit configured to scan each correlation value in the forward and backward directions from the maximal timing to detect a minimal correlation value and to register a timing corresponding to the minimal correlation value as a minimal timing;
• an extractor configured to extract at least one correlation value having a value of a predetermined value or more from the correlation values stored at plural timings having a specified timing interval from the maximal timing to the minimal timing, as a high correlation value candidate;
• and
• a holding unit configured to hold a timing corresponding to the high correlation value candidate as timing information of code synchronism.

A CDMA receiving apparatus comprising:

• a receiver configured to receive a CDMA signal;
• a first correlator configured to generate code correlation values corresponding to a specified code from an output of the receiver;
• a storage device configured to store the correlation values;
• a code synchronous timing determining device configured to determine plural code synchronous timing candidates by reading the correlation values stored in the storage device, the code synchronous timing determining device including a time width designating unit configured to designate a limit number of correlation values data of the correlation values stored in said storage device, and candidate extracting unit configured to extract high correlation values as code synchronous timing candidates from the limit number of correlation values designated by said time width designating unit;
• a control device configured to issue a control signal for controlling code synchronism with the CDMA signal received by using the code synchronous timing candidates obtained from the code synchronous timing determining device;
• plural second correlators configured to issue correlation values at plural timings by the code synchronous timing candidates;
• and
• a combining device configured to sum up the correlation values from the plural second correlators.

A code synchronous timing determining apparatus comprising:

• a correlator configured to acquire correlation values of a code included in a CDMA reception signal and an internal code provided in the apparatus at plural timings in each of a plural given time widths included in a given period;
• a storage circuit configured to store the correlation values corresponding to the plural timings;
• a scanning element to scan the stored correlation values;
• and
• a high correlation candidate holding element configured to hold an identifier and a correlation value at the timing of detection of a higher correlation value of a predetermined value or more by scanning by the scanning element,
• wherein said scanning element includes:
• a holding circuit having a number of data holding stages configured to hold timing information at the plural timings in a time sequence order acquired in relation to the correlation values, the number of the data holding stages being defined to correspond to a limit number of correlation values data of the correlation values stored in said storage circuit;
• a registering circuit configured to retrieve a timing corresponding to a correlation value having at least one maximal value from the information at the plural timings held in the holding circuit, to register the timing as maximal timing;
• and
• candidate extracting unit configured to extract high correlation values as code synchronous timing candidates from the limit number of correlation values held in said holding circuit.