Hybrid OFDM-LFM Waveform Design With Good Correlation Properties via Optimally Allocating Frequency Carriers and Chirp-Rate Polarities

This paper focuses on designing a set of hybrid orthogonal frequency division multiplexing (OFDM)-linear frequency modulation (LFM) waveforms, which strategically real-locates multiple LFM components of a frequency modulated continuous wave to distinct sub-carriers within an available frequency band. The main goal of our the design is to obtain good correlation property of waveforms while concurrently ensuring reasonable frequency agility. To this end, we employ the integrated/peak sideloble level (ISL/PSL) of waveforms as the key metric for correlation evaluation, and we formulate the design task into a multifaceted problem that encompasses both ISL/PSL optimization and arrangements of LFM components with bipolar chirp rates across carriers. The formulated problem for this design is inherently non-convex. To solve it, we adopt a cyclic approach that systematically transforms the formulated problem into two distinct sub-problems. The resolution of each of the two sub-problems is obtained through integer programming techniques, whose effectiveness is verified via simulations.