Patent ID: 9525442
Filing Date: 2016-12-20
CPC Classification: H04B,H04L

Claim Text:
1. An Orthogonal Frequency-Division Multiplexing (OFDM) encoding apparatus for encoding OFDM symbols into an OFDM signal, the OFDM encoding apparatus comprising: first circuitry configured to pre-distort OFDM symbols using a pre-distortion transfer function into pre-distorted OFDM symbols, the OFDM symbols comprising payload data and each being carried on multiple OFDM subcarriers; an OFDM generator configured to generate an OFDM signal from the pre-distorted OFDM symbols by OFDM modulating the pre-distorted OFDM symbols; and filter circuitry configured to filter the OFDM signal to obtain a filtered OFDM signal and to attenuate a spectrum of the OFDM signal in frequency bands outside a signal bandwidth of the OFDM signal by applying a filter transfer function to the OFDM signal, wherein the filter transfer function is a weighted cosine function of 2π multiplied by a frequency of a respective OFDM subcarrier and multiplied by half of a time delay of a first echo tap of the filter circuitry, in a frequency domain; the pre-distortion transfer function is a reciprocal of the filter transfer function; and the first circuitry and the filter circuitry cooperate to form the OFDM signal having a flat characteristic within a pass band of the OFDM symbol.