Exploiting time diversity in spatially correlated channels for OFDM systems

Orthogonal frequency division multiplexing (OFDM) is a multi-carrier block modulation scheme suitable for wireless communications. It is primarily used in high bit rate systems to mitigate intersymbol interference (ISI) due to delay spread. While the ISI caused by delay spread is an annoyance factor, it also provides a multipath diversity advantage if the path gains fade independently. For a multiple antenna OFDM in spatially correlated channels (space diversity limited situations), exploiting this multipath diversity is critical. Along with a novel joint channel estimation technique, we propose methods to exploit fully the available multipath diversity, and thereby compensate for the lack of space diversity in such situations. This is demonstrated using computer simulations for a multiple receive antenna OFDM system.