Scaled-Time OFDM Experiments for Channels Exceeding the Cyclic Prefix

Abstract

Wireless communications experiments at high user velocities can be performed with much less effort at lower velocities by using time-stretching techniques. In OFDM, state-of-the-art time-stretching techniques do not consider the case of channel impulse responses exceeding the length of the cyclic prefix (CP). This is the case in any real-world OFDM system. In particular, multipath scenarios caused by relay nodes commonly found in public railways have a late, strong channel tap. In this work, the authors propose a time-stretching technique that preserves the effects of the insufficient CP with negligible error and without channel knowledge.