C-V2X FSA IEEE 802.11p/bd Internet of Things ME structure MEC MIMO MIMO-NOMA NOMA NZIM Nakagami-m fading RFID Rician TD3 V2X absorber wall age of information beam focusing capture effect combline filter communication-based train control (CBTC) computation offloading deep reinforcement learning edge cache flat gain heuristic path search integrated sensing and communication internet of vehicles medium access control medium access control (MAC)