PAPER Low-Power Hybrid Turbo Decoding Based on Reverse Calculation

SUMMARY As turbo decoding is a highly memory-intensive algorithm consuming large power, a major issue to be solved in practical implemen-tation is to reduce power consumption. This paper presents an efficient re-verse calculation method to lower the power consumption by reducing the number of memory accesses required in turbo decoding. The reverse calcu-lation method is proposed for the Max-log-MAP algorithm, and it is com-bined with a scaling technique to achieve a new decoding algorithm, called hybrid log-MAP, that results in a similar BER performance to the log-MAP algorithm. For the W-CDMA standard, experimental results show that 80% of memory accesses are reduced through the proposed reverse calculation method. A hybrid log-MAP turbo decoder based on the proposed reverse calculation reduces power consumption and memory size by 34.4 % and 39.2%, respectively. key words: log-MAP algorithm, low-power design, Max-log-MAP algo-rithm, reverse calculation, turbo codes, turbo coding, turbo decoding 1