Patent ID: 8121204

Claim:
A method for filtering a received OFDM, Orthogonal Frequency Division Multiplexed, signal to reduce noise, the OFDM signal comprising a plurality of symbols n in the time direction, each symbol comprising a plurality of sub-carriers k in the frequency direction, each a-th sub-carrier of each symbol being transmitted as a pilot sub-carrier with known amplitude and phase, and each symbol having its pilot sub-carriers spaced by b sub-carriers relative to the adjacent symbol, the method comprising the step of: producing a filtered version of a selected pilot sub-carrier to be used in subsequent interpolation, by inputting into respective taps of an m-tap filter, m pilot sub-carriers surrounding the selected pilot sub-carrier, the m pilot sub-carriers each satisfying a relationship between n and k, the relationship defining a diagonal line in the n-k plane; repeating the step of producing a filtered version of a selected pilot sub-carrier for a plurality of pilot sub-carriers; and interpolating the OFDM signal using the plurality of the filtered selected pilot sub-carriers, wherein the interpolating step comprises the steps of interpolating by a factor a/b in the frequency direction and interpolating by a factor b in the frequency direction after interpolating by the factor a/b in the frequency direction.