Preamble searching apparatus and method

A method for searching for preambles to acquire a transmitted signal, comprising the steps of:

• inputting oversampled samples of each chip associated with an antenna from an access slot boundary and storing the inputted samples in a sample buffer;
• reading samples in a period of a plurality of chips from the sample buffer and correlating the read samples with scramble codes to generate signatures corresponding respectively to a plurality of hypotheses;
• calculating an accumulated energy value of each of the signatures;
• and
• sorting the signatures by identical ones and selecting one with a maximum accumulated energy value from among the sorted signatures.

An apparatus for searching for preambles in a mobile telecommunications system employing a code division multiple access system, comprising:

• a first buffer for inputting oversampled samples of each chip associated with a first antenna from an access slot boundary and storing the inputted samples circularly for a plurality of correlation periods;
• a second buffer for inputting oversampled samples of each chip associated with a second antenna after the lapse of a predetermined delay from the access slot boundary and storing the inputted samples only for a specific one of the correlation periods;
• a sample transmitter for reading samples in a period of a plurality of chips from the first and second buffers and transmitting the read samples as a plurality of sample patterns corresponding respectively to a plurality of hypotheses;
• a scramble code transmitter for generating scramble codes at intervals of an access slot and transmitting the generated scramble codes as a plurality of scramble code patterns corresponding respectively to the plurality of hypotheses at intervals of the plurality of chips;
• a plurality of correlators for correlating the samples from the sample transmitter with the scramble codes from the scramble code transmitter to generate signatures corresponding respectively to the hypotheses;
• an energy calculation unit for calculating an accumulated energy value of each of the signatures from the correlators;
• and
• a sort/select unit for sorting the signatures from the correlators by identical ones and selecting one with a maximum accumulated energy value from among the sorted signatures.

An apparatus for searching for preambles in a mobile telecommunications system employing a code division multiple access system, comprising:

• a sample buffer for inputting oversampled samples of each chip associated with an antenna from an access slot boundary and storing the inputted samples circularly for a plurality of correlation periods;
• a sample transmitter for reading samples in a period of a plurality of chips from the sample buffer and transmitting the read samples as a plurality of sample patterns corresponding respectively to a plurality of hypotheses;
• a scramble code transmitter for generating scramble codes at intervals of an access slot and transmitting the generated scramble codes as a plurality of scramble code patterns corresponding respectively to the plurality of hypotheses at intervals of the plurality of chips;
• a plurality of correlators for correlating the samples from the sample transmitter with the scramble codes from the scramble code transmitter to generate signatures corresponding respectively to the hypotheses;
• an energy calculation unit for calculating an accumulated energy value of each of the signatures from the correlators;
• and
• a sort/select unit for sorting the signatures by identical ones and selecting one with a maximum accumulated energy value from among the sorted signatures.