Waveform Design and Accurate Channel Estimation for Frequency-Hopping MIMO Radar-Based Communications

Abstract

Frequency-hopping (FH) MIMO radar-based dual-function radar communication\n(FH-MIMO DFRC) enables communication symbol rate to exceed radar pulse\nrepetition frequency, which requires accurate estimations of timing offset and\nchannel parameters. The estimations, however, are challenging due to unknown,\nfast-changing hopping frequencies and the multiplicative coupling between\ntiming offset and channel parameters. In this paper, we develop accurate\nmethods for a single-antenna communication receiver to estimate timing offset\nand channel for FH-MIMO DFRC. First, we design a novel FH-MIMO radar waveform,\nwhich enables a communication receiver to estimate the hopping frequency\nsequence (HFS) used by radar, instead of acquiring it from radar. Importantly,\nthe novel waveform incurs no degradation to radar ranging performance. Then,\nvia capturing distinct HFS features, we develop two estimators for timing\noffset and derive mean squared error lower bound of each estimator. Using the\nbounds, we design an HFS that renders both estimators applicable. Furthermore,\nwe develop an accurate channel estimation method, reusing the single hop for\ntiming offset estimation. Validated by simulations, the accurate channel\nestimates attained by the proposed methods enable the communication performance\nof DFRC to approach that achieved based on perfect timing and ideal knowledge\nof channel.\n