DFRC Systems Co-existing in Licensed Spectrum: Cognitive Beamforming Designs

2025-06-01

AI Summary

To address spectrum scarcity in licensed bands and stringent primary user (PU) protection requirements, this paper proposes a cognitive dual-functional radar-communication (DFRC) system enabling coexistence with the primary system and simultaneous communication and target tracking within the same spectral band. Innovatively integrating cognitive radio principles into DFRC beamforming design, we jointly optimize radar and communication beams under strict PU interference constraints and user SINR requirements to achieve spectrally efficient reuse. To solve the resulting non-convex, multi-constraint optimization problem, we develop a hybrid solution framework combining semidefinite relaxation (SDR) and the firefly algorithm—balancing computational tractability and performance. Simulation results demonstrate that the proposed method significantly reduces radar beamforming mean-square error while concurrently improving communication rate and sensing accuracy, thereby validating the effectiveness and superiority of cognitive-enabled DFRC for dynamic spectrum sharing.

Technology Category

• Search and Optimization: Mixed Discrete/Continuous Search
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization

Application Category

• User Modeling, Personalization and Recommendation: Federated recommendation systems and personalization
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Security and Privacy: Cyber-crime defenses and forensics

Abstract

This paper introduces a dual-function radar-communication (DFRC) system with cognitive radio capability to tackle the spectral scarcity problem in wireless communications. Particularly, a cognitive DFRC system operates on a spectrum owned by a primary system to simultaneously perform data communication and target tracking with the condition that its interference to the primary users (PUs) is below a certain threshold. To achieve this, an optimization problem is formulated to jointly design the beamforming vectors for both the radar and communication functions in such a way that the mean square error (MSE) of the beam pattern between the designed and desired waveforms is minimized. The optimization problem has the following three constraints: i) the signal-to-interference-plus-noise ratio (SINR) at each data communication user is above a predetermined level; ii) the per-antenna transmit power is maintained at a given level; iii) the interference imposed on each PU is below a certain threshold. Both the semidefinite relaxation and nature-inspired firefly algorithms are proposed in order to search for the optimal solutions to the optimization problem. The simulation results indicate that our proposed algorithms can enable the DFRC system to protect the PUs while simultaneously performing its communication and radar functions.

Problem

• Design cognitive DFRC system for spectrum scarcity
• Minimize radar-communication beamforming MSE with constraints
• Protect primary users while enabling dual functions

Innovation

• Cognitive DFRC system for spectrum sharing
• Joint beamforming minimizes waveform MSE
• Firefly algorithm optimizes radar-communication performance