Tunable wordlength architecture for a low power wireless OFDM demodulator
We present a low power architecture that dynamically controls wordlengths in a wireless OFDM demodulator. Finding the optimum wordlength for digital circuit systems is difficult because the tradeoff between the hardware cost and system performance is not conclusive. Actual circuit systems have large wordlengths at the circuit design level to avoid calculation errors caused by a lack of dynamic range. This indicates that power dissipation can still be reduced under better conditions. We propose a tunable wordlength architecture that dynamically changes its own wordlength according to the communication environment. The proposed OFDM demodulator measures error vector magnitudes (EVMs) from demodulated signals and tunes the wordlength to satisfy the required quality of communication by monitoring the EVM performance. The demodulator can reduce dissipated energy by a maximum of 32 and 24% in AWGN and multipath fading channels.
ofdm wireless communication variable wordlength vlsi architecture