Preamble-based cell identification (CID) schemes are derived for orthogonal frequency division multiplexing (OFDM) systems. They include the optimal schemes based on the Bayesian and the maximum likelihood (ML) approaches, a suboptimal scheme that is a simplification of the ML scheme, and a differential decoding-based scheme that does not require any channel information. The complexities and performances of these CID schemes are examined and compared to existing schemes. The differential decoding-based scheme performs like the suboptimal scheme for most practical channels of interest and outperforms existing schemes, yet it is simpler to implement than the others.