Energy-Aware Computing via Adaptive Precision under Performance Constraints in OFDM Wireless Receivers

To cope with rapid variations of channel parameters, wireless receivers are designed with a significant performance margin to reach a given Bit Error Rate (BER), even for the worst-case channel conditions. Indeed, one of the steps during the design phase is the choice of the architecture bit-width, and the smallest word length that ensures the correct behaviour of the receiver is usually chosen. In this paper, an adaptive precision OFDM receiver is proposed. Significant energy savings come from varying at run time processing bit-width, based on estimation of channel conditions, without compromising the BER constraints. To validate the energy savings, the energy consumption of basic operators has been obtained from real measurements for different bit-widths on a FPGA and a processor using soft SIMD. Results show that up to 63% of the dynamic energy consumption can be saved using this adaptive technique.