DFRC with Improved Communication-Sensing Trade-off via Private Subcarrier Permutations and Pairing with Antennas

Dual function radar communication (DFRC) systems can achieve significant improvements in spectrum efficiency, system complexity and energy efficiency, and are attracting a lot of attention for next generation wireless system design. This paper considers DFRC systems using MIMO radar with a sparse transmit array, transmitting OFDM waveforms, and assigning shared and private subcarriers to active transmit antennas. Sub-carrier sharing allows antennas to modulate data symbols onto the same subcarriers and enables high communication rate, while the use of private subcarriers trades-off communication rate for sensing performance by enabling the formulation of a virtual array with larger aperture than the physical receive array. We propose to exploit the permutation of private subcarriers among the available subcarriers and the pairing between active antennas and private subcarriers to recover some of the communication rate loss. Exploiting the 1-sparse property of private subcarriers, we also propose a low complexity algorithm to identify private subcarriers and detect the antenna-subcarrier pairing.

I. Introduction

Next-generation wireless applications aim to achieve un-constrained access to spectrum for radar and communications, thereby achieving high spectral efficiency. This has given rise to a lot of interest in designing systems that can coexist in the spectrum while using different platforms [1]–[3], or to Dual Function Radar Communication (DFRC) systems that perform sensing and communication from a single platform [4]. The former class can work with existing systems but requires means for controlling the interference between the two systems, for example, via a control center [3]. On the other hand, DFRC systems require new signaling designs, but do not require interference control between radar and communication, and further, they offer reduced cost, lighter hardware, and lower power consumption. For those reasons, DFRC systems are of great interest to vehicular networks, WLAN indoor positioning, and unmanned aerial vehicle networks [4]–[8].