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

Abstract

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 wordlength 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.

Improving Energy Efficiency of OFDM Using Adaptive Precision Reconfigurable FFT

“…• Dynamic analysis, also known as simulation-based method, evaluates the data-flow graph (DFG) of the system; hence, it is not fast, scalable, and robust enough [32,26,12]. • Static analysis, also called analytical method, propagates inputs and errors through the DFG of the design and evaluates the outputs through statistical analysis [29,7,3].…”

“…Recently, a dynamic word-length tunable FFT architecture for a wireless system is proposed where the word-length is scaled according to the run-time conditions such as SNR. In these scenario-oriented methodologies, data format refinement is satisfied based on the run-time conditions and the best working scenario for the current conditions is found, chosen and applied at run-time [29,12].…”

“…A simulation-based DPS OFDM receiver is proposed in [12]. This design improves energy efficiency by tuning the run-time processing word-length, based on periodic estimation of channel conditions while the required BER is satisfied.…”