A dynamically-reconfigurable, power-efficient turbo decoder

The development of turbo codes has allowed for near-Shannon limit information transfer in modern communication systems. Although turbo decoding is viewed as superior to alternate decoding techniques, the circuit complexity and power consumption of turbo decoder implementations can often be prohibitive for power-constrained systems. To address these issues, we have developed a reduced-complexity turbo decoder specifically optimized for contemporary FPGA devices. Our key power-saving technique is the use of decoder run-time dynamic reconfiguration in response to variations in the channel conditions. If less favorable channel conditions are detected, a more powerful, less power-efficient decoder is swapped into the FPGA hardware to maintain a fixed bit error rate. More favorable channel conditions result in the opposite effect. Through experimentation on a stratix-based NIOS development board, we show that dynamic reconfiguration can result in a 52% power reduction versus a static decoder implementation. Comparisons with contemporary microprocessors illustrate a 100× performance improvement.