Patent ID: 8595000

Claim:
A fixed codebook searching apparatus, comprising: a core layer codebook including a first space and a second space into which combinations of possible positions of pulses are classified; a core layer searching unit, implemented by using at least one processing device, to search each of the first and second spaces of the core layer codebook and to determine a least distorted space from among the first and second spaces of the core layer codebook by comparing a distortion value of a first fixed codebook vector selected from the first space with a distortion value of a second fixed codebook vector selected from the second space; an enhancement layer codebook including a first space and a second space corresponding to the first space and the second space of the core layer codebook, respectively; and an enhancement layer searching unit to search the spaces of the enhancement layer codebook excluding the first space or the second space in the enhancement layer codebook that corresponds to the first space or the second space in the core layer codebook determined to be the least distorted space among the first and second spaces of the core layer codebook, wherein both the first space of the core layer codebook and the first space of the enhancement layer codebook comprise one of even-numbered possible pulse positions and odd-numbered possible pulse positions and both the second space of the core layer codebook and the second space of the enhancement layer codebook comprise the other of the even-numbered possible pulse positions and the odd-numbered possible pulse positions.