A precoding scheme for DFT-based OFDM to suppress sidelobes

In spectrum pooling scenario, the spectral leakage of DFT-based OFDM signal can be divided into in-band-out-ofsubband (IBOSB) radiation and out-of-band (OOB) radiation. A precoding scheme is proposed to suppress the IBOSB sidelobes. The precoding design is based on the generalized eigenvalue problem. Simulation results demonstrate that the proposed scheme can suppress the sidelobes significantly in contrast to the uncoded schemes. At the same time, the Bit-Error-Rate (BER) performance of the precoded system over multipath fading channel is improved due to the frequency diversity.

I. Introduction

OFDM is considered to be one of the promising candidates for spectrum pooling systems [1], for its potential of spectrum shaping with flexibility by deactivating some subcarriers. However, the spectral leakage of OFDM signals is too high to guarantee no interference with licensed user (LU).