Low-Complexity Linear Equalization for Block Transmission in Multipath Channels

We address the issue of low complexity linear equalization for cyclic-prefix (CP) and zero-padded (ZP) block transmissions (OFDM). While cyclic-prefix (CP) OFDM does not exploit frequency diversity offered by multipath fading, use of appropriate redundant linear preceding permits a linear equalizer (LE) to benefit from full diversity in the frequency selective channel. We exploit excess time of block transmission (TX) for low-complexity (and full-diversity) linear equalization. Relying on specific structure in the TX scheme, it is shown that excess time can take different forms and impacts diversity order of linear (block) equalization at the receiver (RX). We focus on frequency selective channels and revisit full-diversity low- complexity LE for the ZP case. We discuss special cases of ZP-OFDM with excess time that admit full-diversity LE and draw parallels with the standard ZP case.