Joint Radar-communication System Research Articles

Integrated Waveform for a Joint Radar-Communication System With High-Speed Transmission

Joint radar-communication systems based on integrated waveforms can simultaneously realize high-speed data transmission and target detection in one device, providing information sharing networks and information sources for decision-making of intelligent transportation systems. In this letter, based on a combination of linear frequency modulation (LFM) signals and continuous phase modulation (CPM) signals with an adjustment of communication symbols of length ${k}$ , an integrated waveform ${k}$ -LFM-CPM and a complete system framework cascaded with low-density parity-check (LDPC) codes is carried out. With a limited bandwidth, this system achieves a better bit-error rate than original LFM-CPM-LDPC systems, benefiting from an almost non-broadening power spectrum and additional information used in the cascaded decoding process. Finally, through the optimization of the mismatched filter, it is verified that the detection performance of the integrated waveform with accumulation is almost the same as that of the LFM signal.

Frequency-Hopping Code Design for Target Detection via Optimization Theory

We present a signaling scheme for information embedding into the illumination of radar using frequency-hopping pulses. A frequency-hopping-based joint radar-communication system enables implementing a primary radar operation and a secondary communication function simultaneously. Then, we consider the problems of radar codes optimization under a peak-to-average-power ratio and an energy constraint. These radar codes design problems can be converted into non-convex quadratic programs with a finite or an infinite number of quadratic constraints. All problems are proved to be NP-hard optimization problems. Therefore, we develop optimization approaches, resorting to semi-definite programming relaxation technique along with to the idea of trigonometric polynomials, offering expected approximate solutions with a polynomial time calculation burden. We assess the capability of the proposed schemes, considering both the detection probability and the robustness in correspondence of Doppler shifts offered by the Neyman–Pearson detector. Simulation results show an improvement in detection performance as the average signal-to-noise ratio value increases, while still maintaining low symbol error rates between the proposed system nodes.

Novel Radar Waveform Optimization for a Cooperative Radar-Communications System

We develop and present a novel minimum estimation error variance waveform design method. The method optimizes the spectral shape of a unimodular radar waveform such that the performance of a joint radar-communications system that shares spectrum is maximized. We also develop the novel spectral water-filling successive interference cancelation data rate, which employs the continuous spectral water-filling algorithm to obtain the optimal communications power spectrum. We perform a numerical study to compare the performance of the new technique with the previously derived spectral mask shaping method. The global estimation rate and the data rate capture the radar and the communications performance, respectively.

A mmWave Automotive Joint Radar-Communications System

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.

Toward Millimeter-Wave Joint Radar Communications: A Signal Processing Perspective

Synergistic design of communications and radar systems with common spectral and hardware resources is heralding a new era of efficiently utilizing a limited radio-frequency (RF) spectrum. Such a joint radar communications (JRC) model has advantages of low cost, compact size, less power consumption, spectrum sharing, improved performance, and safety due to enhanced information sharing. Today, millimeter-wave (mmwave) communications have emerged as the preferred technology for short distance wireless links because they provide transmission bandwidth that is several gigahertz wide. This band is also promising for short-range radar applications, which benefit from the high-range resolution arising from large transmit signal bandwidths. Signal processing techniques are critical to the implementation of mm-wave JRC systems. Major challenges are joint waveform design and performance criteria that would optimally trade off between communications and radar functionalities. Novel multiple-input, multiple-output (MIMO) signal processing techniques are required because mm-wave JRC systems employ large antenna arrays. There are opportunities to exploit recent advances in cognition, compressed sensing, and machine learning to reduce required resources and dynamically allocate them with low overheads. This article provides a signal processing perspective of mm-wave JRC systems with an emphasis on waveform design.

High Throughput Rate-Shift Integrated System for Joint Radar-Communications

A rate-shift-based integrated system is proposed to increase the throughput of the joint radar-communications systems. We show that the transmission rate has a time-varying bound and can be maximized with each transmission bit having a different rate. Then, we derive the theoretical throughput of the rate-shift signal, which doubles that of the constant rate signal. For achieving the double throughput, a rate-shift algorithm is proposed to generate the transmission rates of rate-shift signal. The corresponding transmitter and receiver are designed without any additional computational complexity. The numerical results show that the throughput of joint radar-communications systems can be significantly improved by shifting rates.

Waveform Design for Dual-Function Radar-Communication System With Golay Block Coding

In view of the defects that high range side lobes and high peak-to-average power radio (PAPR) in radar and communication integrated systems based on traditional orthogonal frequency division multiplexing (OFDM), a co-designed OFDM waveform based on Golay block coding for joint radar-communication system is proposed in this paper. The communication information is coded into Golay complementary sequences by Reed-Muller codes, which can not only reduce the PAPR of the system, but also can improve the error correction capability. However, the code rate of the algorithm will decrease rapidly with the increase of the number of subcarriers. Furthermore, the traditional block coding would impact on the final superimposed waveform performance due to phase randomness. Hence, a self-disarrange block coding algorithm is proposed. The radar and communication performance of the designed waveform, including wideband ambiguity function, range profile, PAPR, and bit error rate, is analyzed and simulated. The results demonstrate that the PAPR of the waveform and BER can be reduced effectively, while the range side lobes can be decreased for better radar detection performance.

Realizing joint radar-communications in coherent MIMO radars

The increasing interest on spectrum resources causes various efforts on developing smart and compact solutions as joint radar-communication (JRC) systems. A JRC system can offer cost-effective solution with concurrent operation, as target sensing via radar processing and establishing communication links. JRC capability has been proposed over the years for different types of MIMO radars. However, a JRC capable monostatic coherent MIMO radar system is yet to be developed. These radars offer several advantages as fully coherent signal processing and coherent transmit beamforming which provides beampatterns to minimize probability of intercept. In this paper, two new waveform generation techniques suitable for JRC operation without disturbing transmit beamforming requirements and waveform orthogonality condition in space and time domain are proposed for monostatic coherent MIMO radars. Then, new communication methods are introduced for phase coded monostatic coherent MIMO radars. First method uses chirp-wise information encoding inside the radar pulse as intra-pulse communications. Second rotates the phase of a specific waveform on radiated symbols to a specific direction and the last method applies a small amount of progressive phase shift to the radar waveforms emitted from the antennas to create relative phase modulation between selected radar waveforms. Then, the performance of the proposed communication techniques are investigated in terms of bit error rate (BER) and generated waveforms are examined according to the orthogonality and transmit beamforming requirements.

Fusion of radar sensing and wireless communications by embedding communication signals into the radar transmit waveform

A joint radar-communication (JRC) system with both radar sensing and communication abilities is proposed to improve spectrum utilisation efficiency. The transmitter of the JRC consists of multiple antenna subarrays transmitting orthogonal waveforms. If the communication receivers are in radar sidelobe directions, the communication data symbols are embedded in the magnitude ratio as well as the phase shift between transmit waveform pairs. In the case of the communication receivers in radar main lobe direction, the data symbols are embedded in the phase shift between transmit waveform pairs only to preserve optimum radar target detection performance. Novel symbol mapping constellation scheme is designed to achieve a high data transmission rate while maintaining a relatively low symbol error rate. The simulation results show that with medium pulse repetition frequency radar waveforms used, the data transmission rate of the proposed JRC system is in the range of Mbits/s.

On Mutual Interference Cancellation in a MIMO OFDM Multiuser Radar-Communication Network

This paper presents a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) joint radar-communication (RadCom) system and explores its tolerance toward mutual interference. Since OFDM signals are weak toward subcarrier misalignment caused by frequency offsets, some form of interference cancellation will definitely be required for operation in real scenarios. A simple and flexible system level interference cancellation algorithm is proposed, which is to be employed when the radar estimation is no longer reliable. For the proof-of-concept verification, the MIMO RadCom node is implemented on universal software radio peripherals to take hardware imperfections and propagation losses into account. Real-time measurements are also presented to prove the 2D+velocity estimation capability as well as the effectiveness of the interference cancellation algorithm. With this system concept, the dual functions of the RadCom node will be possible in a realistic automotive scenario for vehicle-to-vehicle and vehicle-to-infrastructure communication with the aim of enhancing overall road safety by making driving a collaborative effort instead of an individual one.

Research Challenges, Trends and Applications for Future Joint Radar Communications Systems

The future Internet of Things will integrate sensing and wireless communications. Among the multiple types of sensors to be used, sensors based on the radar principles are of interest for several applications, namely automotive. Dual functionality devices that integrate reflectometry and communication capabilities will be important to reduce development costs through the reuse of modules and to optimise the usage of radio resources, e.g. spectrum. This paper reviews the main trends that push for the merging of radar type sensors and wireless communications (RadCom). It presents the most important use cases that can be currently foreseen and identifies the main technology trends and issues to reach a mature technology, focusing on OFDM type waveforms that will enable a smooth integration with 4G and 5G.

Millimeter-Wave Multifunction Multiport Interferometric Receiver for Future Wireless Systems

In this paper, a receiver architecture is presented which is capable of handling angle-of-arrival (AOA) detection as well as data communication. The architecture of the proposed multifunction receiver is based on the multiport interferometer technique, and it integrates two previously reported six-port-based system functions that were realized as two distinct six-port receivers (SPRs). This unification of two SPRs is mainly achieved through a new configuration of RF/local oscillator (LO) signals at input ports, a new phase processing of the input signals within a structured eight-port passive network and a complementary postprocessing of the signals at the output of detectors. Using two RF input ports and two LO input ports that are switched in two consecutive time slots, the proposed multiport-based receiver (MPR) can estimate the AOA with a simple signal-processing algorithm. The plurality of the RF input ports can cause self-interference for the received communication signals. Therefore, a phasing network within the proposed eight-port wave correlator is devised such that the incoming quadrature modulated RF carriers are demodulated in an orthogonal manner at four output ports. It is found that receiving communication signal from a nonzero AOA makes imbalance between demodulated components. To this end, the proposed MPR can first find the angular position of the other unit and then recover the demodulation components through data fusion and postprocessing. The mathematical model for the developed MPR is derived along with the development of an appropriate calibration technique, and its principal functionality is theoretically analyzed. In addition, a transceiver architecture based on this MPR is implemented, and prototyped for operation around 77 GHz. The techniques for hybrid millimeter-wave system integration are explained in this paper. The proposed concept is proven and concluded with satisfactory measurements for both functions. This unified multifunction MPR can find applications in the future vehicle-to-vehicle radios and joint radar-communication systems.

Performance of a Linear-Detector Joint Radar-Communication System in Doubly Selective Channels

When radar and communication systems are colocated and operating simultaneously in the same frequency band, interference can be addressed by designing the systems to share resources. This paper develops a framework for cooperative operation of single-input single-output bistatic radar and wireless communication systems. We adopt a low-complexity linear minimum mean square error (LMMSE) optimal pilot symbol aided modulation scheme, and show the achievability region of the joint radar-communication system designed for simultaneous operation in a wireless channel that is both frequency and time-selective. Since the LMMSE estimate requires accurate knowledge of channel statistics, we give a lower bound on performance using least-squares estimation that operates purely on the received signal. Finally, to better match power levels between systems, we compare the performance using optimal training sequences with a suboptimal scheme using Barker sequences.

Maneuvering Target Detection Based on JRC System in Gaussian and Non-Gaussian Clutter

Aimed at the problem of detecting maneuvering targets in the Gaussian and sea clutter environments and based on the established motion state model, this paper proposed a new scheme that uses a joint radar-communication (JRC) system with Kalman filter to accurately detect the target with the generalized likelihood ratio test (GLRT) theory and a constant false alarm rate (CFAR) based threshold. Also, the theoretical threshold and probability function of GLRT target detection based on CFAR were given. Moreover, target detection probability of the new JRC system in Weibull andKdistribution clutter is deduced. In addition to theoretical considerations, simulations and measurement results of the new JRC systems demonstrate excellent detection performance for maneuvering targets in the Weibull andKdistribution channel.