Abstract— In this paper, we study the orthogonal frequency division multiplexing (OFDM) system under imperfect channel-acquisition. We consider an OFDM system with a half-symbol-spaced receiver, where we employ a pilot symbol padding scheme for channel acquisition. Also, we use the Kronecker tensor product either at the transmitter to insert pilot symbols among data symbols or at the receiver to extract signals associated with pilots or data symbols. Also, we obtain the symbol detection with the minimal probability of error under imperfect channel acquisition. Results, both simulation and analytical, reveal that channel acquisition error degrades the system performance. However, the OFDM system with a half-symbol-spaced receiver shows better error probability and less acquisition error compared to the OFDM system with a symbol-spaced receiver.