Energy-Adaptive Polar Codes: Trading Off Reliability and Decoder Circuit Energy
It is now well known that using a long and complicated error correcting code (ECC) designed for the worst-case error probability requirement wastes excessive total system energy (transmit + circuit energy) when the error probability requirement is much higher than the worst case. We propose a novel adaptive polar coding strategy that adjusts the decoder circuit to consume minimal decoding circuit energy at each given target error requirement. By combining Thompson’s VLSI theory and scaling analysis of polar codes, we provide upper bounds on energy, area, and time complexity of polar decoding circuits in terms of target block error probability. The upper bounds are derived from an explicit construction of decoder circuit based on mesh-network structure. Our comparison shows that the proposed energy-adaptive coding strategy has a scaling-sense gain in decoding energy with little circuit area overhead when there is a large gap between the worst-case and typical target error rate requirements.