OFDM waveform design compromising spectral nulling, side-lobe suppression and range resolution

Abstract

Motivated by dual use of OFDM signal format for communications and radar in ever-worsening Electromagnetic (EM) coexistence environments, this paper deals with transmit waveform design problem considering multiple design objectives. Spectral nulling is a typical way for friendly coexistence with narrow band systems. However, a Non-Contiguous Orthogonal Frequency-Division Multiplexing (NC-OFDM) waveform generated by turning off the interfering sub-carriers does not lead to satisfactory results. In this paper a convex optimization based waveform design framework is used to achieve deep spectral nulling while retaining low waveform autocorrelation side lobes and good range resolution. Because of dual use of the waveform, the data blocks to transmit are either unknown or chosen from a known dataset. Optimal sub-carrier weights are obtained for given transmission data blocks. In addition, waveform design for unknown data blocks are discussed and examined.