Patent ID: 7436757

Claim:
A method of inserting pilot symbols into orthogonal frequency division multiplexing (OFDM) frames at an OFDM transmitter having at least one transmitting antenna, each OFDM frame comprising a plurality of OFDM symbols, the method comprising the steps of: for the or each transmitting antenna, obtaining historical data regarding channel conditions, and inserting scattered pilot symbols in a scattered pattern dependent upon said historical data, wherein said historical data comprises one or more of signal to noise plus interference ratio (SNIR), dispersion and/or temporal fading, and the spacing of the scattered pilot symbols in time and/or frequency is governed by at least one of: the SNIR, dispersion and/or temporal frequency, and wherein the SNIR, dispersion and/or temporal frequency by which the spacing of the pilot symbols is governed is mapped to one element of a table, each element of the table corresponding to a different range of values of SNIR, dispersion and/or temporal frequency and defining a respective spacing of the pilot symbols to be used.