Apparatus and method for secondary synchronization channel detection in a 3GPP WCDMA receiver

A receiver comprising:

• a radio frequency (RF) front-end capable of receiving an incoming RF signal and down-converting said incoming RF signal to an intermediate frequency (IF) signal, wherein said IF signal comprises a primary synchronization channel (P-SCH) signal, a secondary synchronization channel (S-SCH) signal, and a common control pilot channel (CPICH) signal;
• and
• a pipelined cell search apparatus capable of receiving said IF signal and detecting base station signals therein, said pipelined cell search apparatus comprising a secondary search stage capable of receiving said S-SCH signal, said S-SCH signal comprising one of 64 codewords, wherein each of said 64 codewords comprises a sequence of fifteen slots and each slot comprises one of sixteen valid 256-bit secondary synchronization codes (SSC), wherein said secondary search stage comprises:
• a correlation block for i) correlating said S-SCH signal with a 256-bit sequence z associated with said S-SCH signal to produce a first correlated output sequence and ii) correlating said first correlated output sequence with each one of sixteen Hadamard sequences associated with said S-SCH signal to produce a vector output sequence, where each vector comprises sixteen Hadamard-correlated values, one for said each of said sixteen Hadamard sequences associated with said S-SCH signal;
• a maximum detection block capable of detecting a maximum Hadamard-correlated value in said each vector and generating an index sequence, wherein each index identifies a position of said maximum Hadamard-correlated value in said each vector;
• a Reed-Solomon (R-S) decoding correction block capable of decoding and correcting 15 consecutive indexes in said index sequence and determining a codeword of length 3 associated with said 15 consecutive corrected indexes;
• and
• a frame time detector capable of receiving said codeword of length 3 from said R-S decoding correction block and determining therefrom frame boundary data of said S-SCH signal based on syndrome properties of an R-S code associated with said S-SCH code.

For use in a receiver, a method for detecting a secondary synchronization channel (S-SCH) signal comprising one of 64 codewords, wherein each of the 64 codewords comprises a sequence of fifteen slots and each slot comprises one of sixteen valid 256-bit secondary synchronization codes (SSC), the method comprising the steps of:

• correlating the S-SCH signal with a 256-bit sequence z associated with the S-SCH signal to produce a first correlated output sequence;
• correlating the first correlated output sequence with each one of sixteen Hadamard sequences associated with the S-SCH signal to produce a vector output sequence, where each vector comprises sixteen Hadamard-correlated values, one for the each of the sixteen Hadamard sequences associated with the S-SCH signal;
• detecting a maximum Hadamard-correlated value in the each vector and generating an index sequence, wherein each index identifies a position of the maximum Hadamard-correlated value in the each vector;
• Reed-Solomon (R-S) decoding and correcting 15 consecutive indexes in the index sequence and determining a codeword of length 3 associated with the 15 consecutive corrected indexes;
• and
• determining from the codeword of length 3 frame boundary data of the S-SCH signal based on syndrome properties of an R-S code associated with the S-SCH code.