Solution of Radio Interference for the Integrated Public Network in the 700-MHz Spectrum Band

Radio interference arises because of the shared use of the same spectrum by public safety-LTE (PS-LTE), LTE-railway (LTE-R), and LTE-marine (LTE-M) networks in the 700-MHz integrated public network (IPN) spectrum band. PS-LTE is a broadband communication network used for rapid and efficient communication during disasters, enabling tasks such as search and rescue by firefighters, police, and emergency responders. However, when PS-LTE shares its spectrum with railway and high-speed maritime networks, serious radio interference becomes inevitable in coastal areas or near railway infrastructure during emergencies. To address this challenge, this study analyzes the international spectrum trends of public safety networks, railroad communications networks, and e-navigation networks and proposes a solution to avoid interference. The proposed policy measure reallocates the current IPN spectrum to an exclusive PS-LTE spectrum. Additionally, it aims to reclaim the vacant 710~718-MHz band, the 748~753-MHz band, and the unused EBS ultra-high definition (UHD) broadcasting band. Under this approach, the railway and maritime networks would share a 5-MHz bandwidth of the spectrum. These networks have separate service areas, allowing spectrum sharing with the railway and maritime networks used as the primary and secondary users, respectively. The proposed policy approach fundamentally addresses the serious interference issues between PS-LTE and LTE-R. The proposed policy measure is expected to effectively resolve the serious interference issues currently occurring between public safety and railway networks.