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. There is a tradeoff between power consumption and system performance when searching for the optimum wordlength. We have developed a technique of dynamically controlling the wordlength used in the signal processing algorithms of wireless orthogonal frequency-division multiplexing (OFDM) receivers. The receiver dynamically changes the wordlength on the basis of the conditions in the propagation environment while satisfying the user-required communication quality. That is, the system optimizes the wordlength while operating by sensing its own performance and gradually adjusting this wordlength to improve performance. Testing revealed that, for a packet error rate (PER) of 10-2, the application of this technique to an OFDM receiver reduces energy dissipation by 18.1%-30.2%.