Enhanced C-V2X Mode-3 for CAM and DENM Propagation in Scalable Overlapped eNBs

To improve safety in intelligent transportation systems (ITS), seamless CAM exchange and prompt DENM broad- casting are crucial. This paper presents an enhanced C-V2X mode-3 solution featuring: (i) scalable, overlapping eNBs with orthogonal RF resource management to reduce interference, (ii) smart handover to minimize signaling overhead and ensure smooth CAM delivery, and (iii) efficient DENM propagation via eNB collaboration. The system uses 3 to 4 orthogonal sub-channels per eNB, supporting up to 400 vehicles each, and balances RF channel usage to address the half-duplex problem. Smart handover reduces delays by avoiding re-registration at eNB boundaries. Emergency warnings, collected by vehicles or public warning systems, are delivered as DENMs through system information blocks and swiftly propagated across eNBs. Simulation results show CAM delivery rates exceed 99.8% in congested areas, with DENM propagation within 100 ms.