Complementary Channel Estimation and Synchronization for OFDM

In this paper, we present a new type of packet preamble for orthogonal frequency division multiplexing (OFDM) systems that is based on a complementary sequence pair. It is shown how this approach permits a receiver to dynamically choose between frequency-domain equalization (FDE) and timedomain equalization (TDE). With FDE offering a low-complexity zero-forcing (ZF) equalization and TDE facilitating easy minimum mean square error (MMSE) estimation, it is concluded that a spectrally-flattened complementary sequence pair offers an outstanding combination of flexibility and performance.