Various embodiments are described to provide for the transmission and
reception of data in an improved manner. Data transmission is improved by
including in a transmitter a null generator (110) to generate an output
data symbol sequence that exhibits nulls in the frequency domain at
particular frequencies that an input data symbol sequence does not. A
pilot inserter (120) then adds a pilot symbol sequence to this output
data symbol sequence to create a combined symbol sequence. Since the
pilot symbol sequence exhibits pilot signals corresponding to the nulls
of the output data symbol sequence in the frequency domain, the combined
symbol sequence exhibits pilots that are orthogonal to the data in the
frequency domain.