Joint Radar and Communication Design: Applications, State-of-the-Art, and the Road Ahead

Abstract

For the sake of enhancing the exploitation of the permanently allocated, but potentially under-utilized spectral resources, sharing the frequency bands between radar and communication systems has attracted substantial attention. More explicitly, there is increasing demand for sharing both the frequency band and the hardware platform between these two functionalities, but naturally, its success critically hinges on highquality joint sensing and communications. In this paper, we firstly overview the application scenarios and the research progress in the area of communication and radar spectrum sharing, with particular emphasis on: 1) Radar-communication coexistence; 2) Dual-functional radar-communication (DFRC) systems. In the remainder of the paper, we propose a novel transceiver architecture and frame structure for a DFRC base station (BS) operating in the millimeter wave (mmWave) band, using the hybrid analog-digital (HAD) beamforming technique. We assume that the BS is serving a multi-antenna aided user equipment (UE) operating in a mmWave channel, which in the meantime actively detects multiple targets. Note that part of the targets also play the role of scatterers for the communication signal. Given this framework, we then propose a novel scheme for joint target search and communication channel estimation relying on the omni-directional pilot signals generated by the HAD structure. Given a fully-digital communication precoder and a desired radar transmit beampattern, we propose to design the analog and digital precoders under non-convex constant-modulus (CM) and power constraints, such that the BS can formulate narrow beams towards all the targets, while pre-equalizing the impact of the communication channel. Furthermore, we design an HAD receiver that can simultaneously process signals from the UE and echo waves from the targets. By tracking the angular variation of the targets, we show that it is possible to recover the target echoes and mitigate the potential interference imposed on the UE signals by invoking the successive interference cancellation (SIC) technique, even when the radar and communication signals share the equivalent signal-to-noise ratio (SNR). The feasibility and the efficiency of the proposed approaches in realizing DFRC are verified via numerical simulations. Finally, our discussions are summarized by overviewing the open problems in the research field of CRSS.

A Survey on Joint Communication-Radar Systems

“…The methods of spectrum sharing explored in the literature can be classified into three types [1], namely cohabitation, cooperation and codesign. The main concepts governing these methods are illustrated in Fig.…”

“…However, the radar and communication systems cooperatively exchange information that helps them to keep this interference within tolerable limits. Techniques include implementing such cohabitation by joint power allocation optimized with constraints on qualityof-service (QoS) requirements for both the systems [20] and successive interference cancellation at the receiver [1], [21]. Obviously, the drawback is that the mutual interference and consequent degradation in both systems' performances are inevitable.…”

“…Therefore, there are a number of applications that stand to benefit from the integration of radar and communication functions. Hence, spectrum sharing between radar and communication systems has attracted significant interest in recent years [1]- [3].…”

“…Several methods have been proposed in which a radar and a communication system can share a common spectrum [4]. The methods can be broadly classified into three categories, namely 1) Cohabitation or Coexistence, 2) Cooperation and 3)…”

“…Nevertheless, very little work has been done in this direction. On the other hand, there have been significant developments in JRC system design, which have been surveyed in a number of recent articles [1], [2], [7]. Therefore, in this article, we focus on reviewing the research on JCR systems.…”