Accurate Channel Estimation for Frequency-Hopping Dual-Function Radar Communications

Abstract

Dual-function radar communications (DFRC) is proposed recently to embed information into radar waveform, and hence performs data communications by sharing radar apertures and frequency resources. Exploiting a frequency-hopping (FH) MIMO radar, DFRC can achieve the symbol rate that is larger than the radar pulse frequency. However, this requires an accurate channel estimate, which is challenging to achieve due to the non-cooperative radar transmission and the fast-changing FH waveform. In this paper, we propose an accurate channel estimation method for the DFRC based on FH-MIMO radars. We design a new FH-MIMO radar waveform which incurs no change to the ranging performance of the radar. The new waveform also enables a communication receiver to estimate the channel without knowing the pairing between hopping frequencies and antennas. We also develop a new angle estimation method at a singleantenna communication receiver using as few as one symbol, i.e., a single hop. Simulations are provided to validate the efficacy of the proposed channel estimation method. Specifically, the symbol error rate achieved based on the estimated channel approaches to that based on the ideal channel.

Frequency-Hopping MIMO Radar-Based Communications: An Overview

“…where P = 1 is taken as in prior works [10]- [16] and δ(l) is the Dirac delta function. The noise term is dropped for illustration convenience.…”

“…M , the data rate of FHCS first increases with M , then saturates as M reaches K/2, and starts decreasing as M keeps increasing, due to the binomial coefficient in its rate expression. To improve the data rate, FHCS can be employed in combination with the phase modulation schemes, as developed in [16], [17]. However, the cost of the rate improvement is that more necessary information will be required for demodulation.…”

“…As illustrated above, most existing signaling schemes for FH-MIMO DFRC require accurate channel information to perform demodulation. Yet, to the best of our knowledge, only a few published work [16], [17] develop channel estimation scheme for FH-MIMO DFRC. In this section, we first review the channel estimation methods designed for DFRC (not based on FH-MIMO radar), and then briefly introduce the solution developed in [16].…”

“…In [16], a channel estimation scheme is developed for FH-MIMO DFRC to estimate the hopping frequencies and channel parameters, assuming an accurate timing.…”

“…Yet, little attention is paid to effective implementation of data communications. Some latest research reported in [16]- [18] develops methods to address the practical issues, e.g., channel estimation and synchronization, in FH-MIMO DFRC.…”