TURBO DECODER USING BASE 2 LOG MAP(MAXIMUM A-POSTERIORI PROBABILITY)

摘要

PURPOSE: A turbo decoder using base 2 log MAP(maximum a posteriori probability)is provided to reduce size of the hardware without degradation of performance by converting complex E function to simple 2 function. CONSTITUTION: The turbo decoder extracts respective excess information from the first and second information sets using the maximum a posteriori probability(MAP) algorism. The turbo decoder has a 2 function device. The 2 function device transforms the MAP algorism using base 2 logarithm. The turbo decoder adds 2-exponential values of the respective first and second information sets each other, defines 2 function taking base 2 logarithm to the added value and calculates the 2 function in the transformed MAP algorism. Therefore it reduce size of the hardware without degradation of performance by converting complex E function to simple 2 function.