A Practical Spectrum Sharing Solution for Real-World Wireless Systems

Spectrum sharing has emerged as a critical strategy to address the growing demand for wireless connectivity in an era of rapidly expanding mobile data, IoT, and emerging 5G/6G applications. Traditional static spectrum allocation often leads to inefficient utilization, with some licensed bands underused while unlicensed bands become congested. By enabling multiple users, services, or technologies to dynamically access the same frequency resources, spectrum sharing improves overall spectral efficiency, reduces spectrum scarcity, and fosters innovation. It allows operators, enterprises, and government agencies to make better use of limited spectrum, supporting diverse use cases such as private 5G networks, smart manufacturing, public safety, and broadband access. As wireless networks continue to evolve, spectrum sharing will play a vital role in achieving scalable, cost-effective, and sustainable connectivity.

In this project, we propose a practical underlay spectrum sharing scheme for cognitive radio networks (CRNs), where primary users remain oblivious to the presence of secondary users. The key components of our scheme are two MIMO-based interference cancellation (IC) techniques designed to manage cross-network interference on the secondary network side:

• Blind beamforming: This technique is applied at secondary transmitters. It allows a secondary transmitter to nullify its generated interference toward primary users without requiring channel state information (CSI).

• Blind interference cancellation (BIC): This technique is applied at secondary receivers. It enables a secondary receiver to decode its desired signal in the presence of strong, unknown interference from primary transmitters.

Based on these two MIMO-based IC techniques, we develop a MAC protocol for the secondary network to enable underlay spectrum sharing in CRNs. The proposed scheme has been implemented on a GNURadio–USRP2 wireless testbed, and experimental results demonstrate that secondary users can achieve an average of 1 bitsHz spectral efficiency without degrading the performance of primary users, even in a real-world office building environment.