Patent ID: 7508805

Claim:
A method for decoding coded data in one frame transmitted from a transmitter at one data rate of a plurality of data rates by a turbo decoder of a receiver having no information on a data rate at which the coded data is transmitted, and detecting a data rate of the coded data, comprising the steps of: (a) decoding the coded data in the frame at a selected data rate of the plurality of the data rates by the turbo decoder and calculating a current decoding state value indicating an average of absolute values of log likelihood ratio (llr) values being identical to decoded values of the coded data, output from the turbo decoder; (b) calculating a current under-decoding state value defined as a difference between the current decoding state value and a previous decoding state value; (c) comparing the current decoding state value with a first threshold; (c-1) performing CRC (Cyclic Redundancy Check) checking on the decoded data if the current decoding state value is larger than a first threshold; (c-2) comparing the current under-decoding state value with a second threshold if the current decoding state value is not larger than a first threshold; (c-3) performing CRC checking on the decoded data if the current under-decoding state value is larger than a second threshold; and (d) determining the selected data rate as a data rate of the coded data transmitted from the transmitter, if the CRC checking result is good.