Method and apparatus for perfoming cell search and frequency offset estimation

An apparatus for performing a cell search in a communication system, the apparatus comprising:

• a scrambling code detection unit configured to identify a scrambling code by correlating a common pilot channel with a first synchronization accumulation length based on a frame boundary and a code group;
• a multipath search unit configured to search for a multipath signal by correlating the common pilot channel with a second synchronization accumulation length based on the frame boundary and the code group;
• and
• a comparator configured to:
• determine a difference between, or a ratio of, a first maximum value of first correlation values acquired during identification of the scrambling code and a second maximum value of second correlation values acquired during searching for the multipath signal;
• determine whether a frequency offset exists by comparing the difference or the ratio with a predetermined threshold value;
• and
• estimate the frequency offset and transmit the frequency offset to a demodulator, when the frequency offset exists,
• wherein the first synchronization accumulation length is different from the second synchronization accumulation length.

A chip set for performing a cell search method in a communication system, the method comprising:

• identifying a scrambling code by correlating a common pilot channel with a first synchronization accumulation length based on a frame boundary and a code group;
• searching for a multipath signal by correlating the common pilot channel with a second synchronization accumulation length based on the frame boundary and the code group;
• determining a difference between, or a ratio of, a first maximum value of first correlation values acquired during identification of the scrambling code and a second maximum value of second correlation values acquired during searching for the multipath signal;
• determining whether a frequency offset exists by comparing the difference or the ratio with a predetermined threshold value;
• and
• estimating the frequency offset and transmit the frequency offset to a demodulator, when the frequency offset exists,
• wherein the first synchronization accumulation length is different from the second synchronization accumulation length.