Fair and Secure 5G and Wi-Fi Coexistence Using Robust Implicit Channel Coordination

5G and Wi-Fi systems are embracing coexistence in the unlicensed portions of the 5–7 GHz bands recently allocated by FCC to support the increasing data rate demands for the growing number of wireless users. To achieve fair and effective spectrum sharing, both 5G and Wi-Fi rely on carrier sensing for medium access. However, differences in sensing thresholds create an unfair advantage for 5G nodes, as they access the medium more aggressively and degrade the data rate and latency of Wi-Fi users. We first demonstrate how an adversary can stealthily exploit this unfairness to further reduce the spectrum occupancy of Wi-Fi nodes, effectively denying Wi-Fi services. Accordingly, in this paper, we propose a novel implicit channel coordination (ICC) approach to both mitigate starvation attacks and improve spectrum access fairness under practical considerations like noise and strong adversaries who try to circumvent our technique. In ICC, Wi-Fi access points (APs) influence 5G gNBs into choosing a precoding matrix that nearly nullifies 5G downlink signals at the APs, enabling concurrent gNB and AP transmissions while accounting for a hidden terminal problem this creates. We theoretically analyze and show that our ICC mitigates novel attacks we have identified, and experimentally demonstrate on a USRP testbed its resilience against starvation attacks. Our design outperforms prior work by achieving an overall 30% higher data rate of the 5G and Wi-Fi coexistence system, 3x improvement in spectrum access fairness, and 1.5x in system capacity, all while conforming with the latency requirements of 5G.