Cyclic Prefix Based Enhanced Data Recovery in OFDM

In this correspondence, we show how the cyclic prefix (CP) can be used to enhance the performance of an orthogonal-frequency-division multiplexing (OFDM) receiver. Specifically, we show how an OFDM symbol transmitted over a block fading channel can be blindly detected using the output symbol and associated CP. The algorithm boils down to a nonlinear relationship involving the input and output data only that can be used to search for the maximum-likelihood (ML) estimate of the input. This relationship becomes much simpler for constant modulus (CM) data. We also propose iterative methods to reduce the computational complexity involved in the ML search of the input for CM data.