Low-power log-MAP turbo decoding based on reduced metric memory access

Due to the powerful error correcting performance, turbo codes have been adopted in many wireless communication standards. Although several low-power techniques have been proposed, power consumption is still a major issue to be solved in practical implementations. Since turbo decoding is classified as a memory-intensive algorithm, reducing memory accesses is crucial to achieve a low power design. To reduce the number of memory accesses for maximum a posteriori (MAP) decoding, this paper proposes an approximate reverse calculation of backward metrics which can be implemented with simple computational complexity. Simulation results show that the proposed method applied to W-CDMA standard reduces the access rate of the backward metric memory by 90% without degrading error correcting performance. A prototype turbo decoder based on the proposed reverse calculation achieves 30% power reduction compared to the conventional decoder.

• Type: Conference
• Year: 2005
• Where: ISCAS
• Authors: Dong-Soo Lee, In-Cheol Park
• Keywords: Backward Metric, Error Correcting Performance, ISCAS 2005, Memory Accesses