Since traditional radar signals are “unintelligent,” regarding the amount of information they convey on the bandwidth they occupy, a joint radar and wireless communication system would constitute a unique platform for future intelligent transportation networks effecting the essential tasks of environmental sensing and the allocation of ad-hoc communication links, in terms of both spectrum efficiency and cost-effectiveness. In this paper, approaches to the design of intelligent waveforms, that are suitable for simultaneously performing both data transmission and radar sensing, are proposed. The approach is based on classical phase-coded waveforms utilized in wireless communications. In particular, requirements that allow for employing such signals for radar measurements with high dynamic range are investigated. Also, a variety of possible radar processing algorithms are discussed. Moreover, the applicability of multiple antenna techniques for direction-of-arrival estimation is considered. In addition to theoretical considerations, the paper presents system simulations and measurement results of complete “RadCom” systems, demonstrating the practical feasibility of integrated communications and radar applications.

Waveform Design and Signal Processing Aspects for Fusion of Wireless Communications and Radar Sensing

Wireless mediums, such as RF, optical, or acoustical, provide finite resources for the purposes of remote sensing (such as radar) and data communications. Often, these two functions are at odds with one another and compete for these resources. Applications for wireless technology are growing rapidly, and RF convergence is already presenting itself as a requirement for both users as consumer and military system requirements evolve. The broad solution space to this complex problem encompasses cooperation or codesigning of systems with both sensing and communications functions. By jointly considering the systems during the design phase, rather than perpetuating a notion of mutual interference, both system’s performance can be improved. We provide a point of departure for future researchers that will be required to solve this problem by presenting the applications, topologies, levels of system integration, the current state of the art, and outlines of future information-centric systems.

Survey of RF Communications and Sensing Convergence Research

We propose a millimeter-wave joint radar-communications (JRC) system comprising a bi-static automotive radar and vehicle-to-vehicle communications. We study the applicability of known phase-modulated-continuous-wave (PMCW) and orthogonal-frequency-division-multiple-access waveforms for bi-static-JRC. In both cases, we design multiplexing strategies to ensure the parameter identifiability, derive JRC statistical bounds and numerically demonstrate superior performance of proposed low-complexity JRC super-resolution algorithms over conventional two-dimensional fast Fourier transform/MUltiple SIgnal Classification.

A mmWave Automotive Joint Radar-Communications System

i»?Phased-array antennas are known for their capability to electronically steer a beam with high effectiveness, but beam steering is fixed in an angle for all range cells. This paper reviews frequency diverse array (FDA) antennas. Different from a phased array, an FDA uses a small frequency increment, as compared with the carrier frequency, across array elements. The use of a frequency increment generates an array factor that is a function of the angle, the time, and the range, allowing the FDA antenna to transmit the energy over the desired range and angle. In addition to analyzing FDA factor characteristics, this paper investigates FDA potential applications in range-dependent energy control and technical challenges in system implementation, with an aim to call for further investigations on the FDA.

Frequency Diverse Array Antenna: New Opportunities

The historical development and current state-of-the-art of various joint wireless communication and radar sensing systems are reviewed and discussed in this study. Different kinds of systems are categorised according to their modulation waveforms and duplex schemes. Pros and cons of each category are highlighted. To showcase the current research advances, several demonstration systems are introduced with emphasis on proposed research contributions in this emerging area, and their performances are compared with respect to both communication and radar modes. Also, a number of challenges are identified for the near future system developments and applications.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-map.2012.0450

Joint wireless communication and radar sensing systems - state of the art and future prospects

The OFDM communication signal is proposed for spread spectrum radar signal generation. A radar signal processing technique is developed to solve the Doppler ambiguity in the pulsed Doppler radar by exploiting the multicarrier structure of the OFDM and the random phase modulation on the carriers in a Doppler compensation scheme. The novel processing technique is analyzed in detail, through both analytical derivations and Monte Carlo simulations, to demonstrate the feasibility of using the OFDM modulation with random phase coding for radar signals.

OFDM Signals as the Radar Waveform to Solve Doppler Ambiguity

A processing technique that utilizes the OFDM communication waveform as the radar waveform is considered. The double use of the waveform for communications and radar enables establishing radar networks communicating through the radar beam. The processing technique exploits the Doppler sensitivity of the OFDM to reduce the Doppler ambiguity. An enhancement to the waveform and the processing is proposed to completely eliminate the Doppler ambiguity.

Multi-carrier radar waveform schemes for range and Doppler processing

A processing technique, which exploits the structure of the multi-carrier signal to obtain range and radial velocity information from the echo signal, is proposed. The novel processing technique executes the Doppler matched filter bank digitally, and solves the ambiguity in the radial velocity measurements in one train of multi-carrier pulses as a result of Doppler sidelobes of the ambiguity function being lower. The processing technique, being independent of the phase coding on the multiple carriers, enables integration of communication and radar waveforms.

Solving Doppler ambiguity by Doppler sensitive pulse compression using multi-carrier waveform

Experimental set up demonstrating combined use of OFDM for radar and communications

A multi-channel receiver has been developed for radar systems with digital beamforming. The design achieves a low cost, small volume, and low dissipation per receiver channel, combined with large dynamic range and a high noise immunity. Important aspects are the shielding of all internal connections by a specially designed packaging, a high degree of integration including A/D-converter and digital pre-processing in the receiver module, and a fiber optical link to transmit the output data to the signal processing. The article describes the design of the multichannel receiver and shows some experimental results obtained from a production unit.

http://ieeexplore.ieee.org/iel3/3929/11378/00522545.pdf

W. J. A. de Heij

Papers

OFDM Signals as the Radar Waveform to Solve Doppler Ambiguity

Multi-carrier radar waveform schemes for range and Doppler processing

Solving Doppler ambiguity by Doppler sensitive pulse compression using multi-carrier waveform

Experimental set up demonstrating combined use of OFDM for radar and communications

Multi-channel receiver and optical data link for radar systems with digital beamforming