CDMA demodulating apparatus and method and CDMA mobile communication system

A CDMA demodulating apparatus for demodulating a CDMA burst signal sent by random access and containing communication control data, said apparatus comprising:

• timing detection means which detects de-spreading timing of said CDMA burst signal based on a correlation value between said CDMA burst signal and a reference code;
• delay means which delay s said CDMA burst signal;
• de-spreading means which:
• de-spreads, by a first processing clock, a second-half portion of a CDMA burst signal not delayed by said delay means which begins after a lapse of said timing detection time, thereby generating a second-half demodulated signal;
• and after sa id de-spreading, de-spreads, by a second processing clock faster than said first processing clock, a first-half portion of said CDMA burst signal delayed by said delay means which extends from the beginning of said CDMA burst signal to the beginning of said second-half portion, thereby generating a first-half demodulated signal;
• and
• reconstructing means which selects said first-half demodulated signal generated by said de-spreading means and, upon completion of said selection, selects said second-half demodulated signal in success ion to said first-half demodulated signal, thereby obtaining a demodulated signal corresponding to said CDMA burst signal in its entirety.

A CDMA demodulating apparatus for demodulating a CDMA burst signal sent by random access using any one of plural time offsets repeating in a predetermined cycle and containing communication control data, said apparatus comprising:

• timing detection means which detects de-spreading timing of said CDMA burst signal for each time offset, based on a correlation value between said CDMA burst signal and a reference code;
• delay means which delays said CDMA burst signal for at least a timing detection time configured to allow a detection of the de-spreading time by said timing detection means;
• first de-spreading means comprises:
• means a number of which is larger than a number of said time offsets by one, which are each assigned time offsets in a repeating cyclic order, and which, when assigned other time offsets than a last one of one cycle, de-spread CDMA burst signals delayed by said delay means and corresponding to said assigned time offsets, using de-spreading timing detected by said timing detection means and corresponding to said assigned time offsets, thereby generating a demodulated signal corresponding to the whole CDMA burst signal;
• and
• means which, when assigned the last time offset of one cycle, de-spreads, at the de-spreading timing detected by said timing detection means and corresponding to said assigned time offset, a first-half portion of the CDMA burst signal delayed by said delay means and corresponding to said assigned time offset which extends from the beginning of said CDMA burst signal to at least a point after the lapse of timing detection time, thereby generating a first-half demodulated signal;
• second de-spreading means which is assigned a last time offset of one cycle and, in parallel with the de-spreading by said first de-spreading means assigned the last time offset of one cycle and at the de-spreading timing detected by said timing detection means and corresponding to said assigned time offset, de-spreads a second-half portion of a CDMA burst signal not delayed by said delay means and corresponding to said assigned time offset which extends from the end of said first-half portion to the end of said CDMA burst signal, thereby generating a second-half demodulated signal;
• and
• plural reconstructing means each of which selects said first-half demodulated signal generated by said first de-spreading means and assigned the last time offset of one cycle, and upon completion of said selection, selects said second-half demodulated signal generated by said second de-spreading means, in succession to said first-half demodulated signal, thereby obtaining a demodulated signal corresponding to the CDMA burst signal in its entirety.

A CDMA demodulating method for demodulating a CDMA burst signal sent by random access and containing communication control data, said method comprising the steps of:

• detecting a de-spreading timing of said CDMA burst signal based on a correlation value between said CDMA burst signal and a reference code;
• delaying said CDMA burst signal for at least a timing detection time to detect the de-spreading time;
• at the de-spreading timing detected by said timing detection means de-spreading by a first de-spreading means a second-half portion of a CDMA burst signal not delayed, thereby generating a second-half demodulated signal;
• in parallel with said de-spreading by said first de-spreading means and at the detected de-spreading timing, de-spreading a first-half portion of said delayed CDMA burst signal by a second de-spreading means thereby generating a first-half demodulated signal;
• selecting said first-half demodulated signal generated by said second de-spreading means and, upon completion of said selection;
• selecting said second-half demodulated signal in succession to said first-half demodulated signal;
• reconstructing a demodulated signal corresponding to said CDMA burst signal in its entirety.

A CDMA demodulating method for demodulating a CDMA burst signal sent by random access and containing communication control data, said method comprising the steps of:

• detecting a de-spreading timing of said CDMA burst signal based on a correlation value between said CDMA burst signal and a reference code;
• delaying said CDMA burst signal;
• de-spreading by a first processing clock, an undelayed second-half portion of said CDMA burst signal, thereby generating a second-half demodulated signal;
• and
• after said de-spreading by a first processing clock, de-spreading by a second processing clock faster than said first processing clock a first-half portion of said delayed CDMA burst signal, thereby generating a first-half demodulated signal;
• selecting said first-half demodulated signal;
• selecting said second-half demodulated signal in succession to said first-half demodulated signal;
• and
• reconstructing a demodulated signal corresponding to said CDMA burst signal in its entirety.