Preamble design for multiple-antenna OFDM

In this paper, we pursue the preamble design for multiple-antenna orthogonal frequency division multiplexing (OFDM) communications over frequency-selective channels. To reduce the overhead and minimize the peak-to-average power ratio, we propose a preamble consisting of a single constant-modulus training sequence per transmit-antenna. This proposed design is shown capable of not only achieving reliable frequency and time synchronization but also facilitating low-complexity channel estimation. Furthermore, when synchronization is perfect, it is optimal in the sense of minimizing the mean squared error of least-squares channel estimation. The performance of the proposed design is investigated via simulations and compared with a competing alternative.