Generalized OFDM for 5th Generation Mobile Communications

Abstract

In this paper, we propose a generalized OFDM (G-OFDM) to map data vectors to channel vectors through filter matrices unlike the conventional OFDM mapping data to subchannels by one to one. Filter matrices play a role to control the spectrums of input data vectors to reduce spectral leakages significantly unlike OFDM which does not have controllability for spectrum. The filter matrix consists mainly of an initial matrix, a jump matrix and the nearest matrix with orthonormal columns. The initial matrix is constructed with minimum nonzero elements to minimize operations when multiplying with other matrix. The jump matrix is constructed by a proper matrix from the initial matrix so that the sum of all elements for each column vector of the matrix becomes zero after subtraction. In this method, a pilot vector to estimate a communication channel which is very similar to pilot symbol inserting methods in OFDM is included in the filter matrix. It was confirmed that the proposed G-OFDM has a superior characteristic in reducing spectral leakage to that of OFDM.