Use of a Variable Wordlength Technique in an OFDM Receiver to Reduce Energy Dissipation

Wordlength determination is an indispensable task in digital hardware implementations of signal processing algorithms because the wordlength affects power consumption and system performance. Actual digital systems add extra bits in circuit design to avoid the worst condition caused by lack of dynamic range. However, they still have room to reduce a wordlength during better conditions. We present a variable wordlength technique for dynamically controlling the wordlength used in wireless OFDM receivers. The key point is that the receiver optimizes the wordlength while operating by sensing current receiver performance. The proposed technique can reduce a wordlength compared with use of a fixed wordlength and satisfy the user-required communication quality of PER. The results show that the receiver has reduced dissipated energy by 18.1 to 30.3% with the PER criterion of 10^-2.