  All practical OFDM systems require a prefix to eliminate inter-symbol
interference at the receiver. Cyclic prefix (CP) and zero-padding are
well-known prefix construction methods, the former being the most employed
technique in practice due to its lower complexity. In this paper we construct
an OFDM system with a generalized CP. It is shown that the proposed generalized
prefix effectively makes the channel experienced by the packet different from
the actual channel. Using an optimization procedure, lower bit error rates can
be achieved, outperforming other prefix construction techniques. At the same
time the complexity of the technique is comparable to the CP method. The
presented simulation results show that the proposed technique not only
outperforms the CP method, but is also more robust in the presence of channel
estimation errors and mobility. The proposed method is appropriate for
practical OFDM systems.
