Enhancing Dual-Function Radar and Communication: A Constrained Frequency Hopping Approach for Optimized Performance

Combining radar and communication functions in a single system has become an increasingly interesting area of research, especially as we see growing demands in wireless communication, autonomous navigation, and advanced sensing. Dual-functional radar-communication (DFRC) systems hold the promise of performing both radar and communication tasks through a single shared waveform. This integration offers major benefits, such as cutting down on hardware, power usage, and even spectrum resources. However, achieving this kind of integration effectively is no simple task. Radar and communication systems have fundamentally different needs: radar relies on highly detailed, low-interference signals for accurate target detection, while communication systems focus on reliable data transmission with low symbol error rates (SER) over varying distances. Balancing these different needs in one DFRC system poses unique challenges that researchers in this field are working hard to overcome. A major difficulty in DFRC systems is finding the right balance between maintaining communication quality and achieving radar accuracy. Typical radar waveforms, like Frequency Modulated Continuous Wave (FMCW), are designed to achieve high precision and low interference in detecting range and velocity. But when these waveforms are used for communication, they can lead to higher symbol error rates and signal degradation, which affects the quality of data transmission. On the other hand, frequency hopping—a technique commonly used to cut down on interference and improve spectrum efficiency in communication—can create issues in radar applications by introducing unwanted sidelobes and out-of-band leakage. These effects reduce radar accuracy and are especially challenging in dense settings, such as urban 5G networks, autonomous vehicle communications, and crowded IoT networks, where both minimal interference and efficient spectrum use are crucial.

In a new study published in the Journal of Signal Processing, Dr. Rui Xu, PhD candidate Ruiming Wen, Dr. Gang Li, Dr. Chu Chu, and led by Professor Guangjun Wen from the School of Information and Communication Engineering at the University of Electronic Science and Technology of China proposed new ways to improve DFRC system design by combining FMCW with constrained frequency hopping (C-FH) to create a waveform that can support both radar and communication functions efficiently, without compromising on either. Their approach aims to tackle high symbol error rates and out-of-band leakage—two of the main issues that limit DFRC effectiveness today.

Dr. Rui Xu et al. kicked off their experiments by creating a realistic simulation that would mirror the environments where DFRC systems are actually used—places like crowded city centers or networks of autonomous vehicles, which are often packed with interference and overlapping signals. Their aim was to see how well their new C-FH-chirp waveform would perform in handling both radar and communication needs in these challenging conditions. In this setup, they generated waveforms that combined FMCW signals with constrained frequency hopping. One key measure they focused on was the radar’s range profile, essentially tracking how accurately the radar could detect and monitor targets at varying distances. They found that the C-FH technique noticeably cut down on radar sidelobes—those unwanted signal distortions that tend to muddy up target detection. Reducing these sidelobes made a real difference in the clarity of radar readings, helping it separate real targets from background noise, even in a busy signal environment. The next focus was on communication quality, especially how well the C-FH-FMCW waveform held up in terms of SER when exposed to interference. The researchers introduced different levels of noise and interference into their simulation, creating a rigorous test of the waveform’s performance compared to traditional DFRC waveforms. The results showed that the C-FH waveform achieved a significantly lower SER, keeping data clear and reducing transmission errors even in noisy conditions. This finding was particularly promising because it suggested that the constrained frequency hopping could be a game-changer in managing interference—an ongoing issue in dual-purpose systems that handle both radar and communication. Plus, the researchers noticed that out-of-band leakage, a common problem where communication signals spill over into radar frequencies, was minimized. This improvement points to better spectrum efficiency, which is especially useful when radar and communication functions share bandwidth. The team took it a step further by testing the radar’s ability to pick up targets accurately using range-bin phase compensation (RBPC), a technique they brought in to improve radar resolution. By adding time-domain extension with RBPC, the radar system reached an accuracy level closer to what you’d expect from specialized FMCW radar systems. This adjustment meant that the radar could capture sharp, clear images of targets without compromising the quality of communication. This feature turned out to be a significant advantage, as it allowed the radar to give precise readings without adding extra processing demands—an important factor for real-time operations.

In conclusion, the new study by Professor Guangjun Wen and colleagues holds real potential for changing how DFRC systems are used, especially in complex, busy environments where interference and inefficiency have traditionally held these systems back. By developing a new waveform that combines FMCW with C-FH, the researchers introduced a design that improves both radar precision and communication reliability—without forcing a compromise on either side. This innovation could be particularly useful in places like dense urban settings, autonomous vehicle networks, and military applications, where both clear detection and smooth, reliable data transmission are essential. We believe one of the biggest takeaways from this research is its promise for making much better use of the available spectrum. As demand for wireless communication grows, efficient spectrum use becomes even more important. The new waveform’s constrained frequency hopping helps cut down on out-of-band leakage and reduces radar sidelobes—signal issues that can often interfere with accuracy. This streamlined spectral use allows DFRC systems to operate in tightly controlled frequency bands without causing interference for nearby systems. This efficiency could have wide-ranging applications, making it easier for DFRC systems to work alongside other technologies and opening doors for future growth in networked communication spaces. Moreover, the study also sheds light on how DFRC systems could work in environments that are especially challenging due to high levels of interference. The C-FH waveform showed a lower SER, which is essential for keeping data clear and reliable. This improvement makes the system highly adaptable in settings where conventional DFRC methods might struggle, like crowded electromagnetic environments in busy cities, where multiple systems need to run smoothly alongside each other. Beyond immediate practical gains, this research could also push DFRC technology closer to becoming a standardized solution. By creating a single, efficient waveform that serves both radar and communication needs with lower processing demands, the approach offers a scalable model that could be tailored to different platforms and industries. As more sectors start to rely on DFRC for continuous tracking, navigation, and data exchange, having a standard that promotes spectrum efficiency, clarity, and reduced interference could be game-changing.