On reducing the average complexity of turbo decoding with application to W-CDMA

A simple but effective method for reducing the average complexity (and power consumption) of turbo decoding with negligible performance degradation in a W-CDMA environment is introduced. It modifies the conventional turbo-CRC decoding scheme by performing two CRC tests per iteration to detect at the earliest a correctly converged decoding process. When applied to a W-CDMA turbo code with frame length 640 bits at a BER of 10(-6), it can save about 50% of the average decoding complexity, relative to the conventional scheme. Further complexity reduction can be achieved by integrating the CRC lest as an intermediate step in the component SISO decoder. In general, the proposed scheme is more attractive for short-frame and low-BER applications.