ISI-Free Block Transceivers for Unknown Frequency Selective Channels

The orthogonal frequency-division multiplexing (OFDM) transceiver has enjoyed great success in many wideband communication systems. It has low complexity and robustness against channel-induced intersymbol interference (ISI). When the channel order does not exceed the length of cyclic prefix, any frequency-selective channel is converted to a set of frequency-nonselective subchannels. This channel-independent ISI-free property is useful for many applications. In this correspondence, we study general block transceiver with such a property. We will show that the solutions of channel-independent ISI-free block transceivers are given in a closed form. It is found that except for some special cases, the solutions are identical to the Lagrange-Vandermonde and Vandermonde-Lagrange transceivers