In L4 autonomous driving scenarios, stable data transmission is the cornerstone of safety and reliability. However, issues such as discontinuous coverage, frequent handovers,  weak wireless coverage and roaming restrictions with single-carrier networks pose a constant threat to the service continuity for connected vehicles. Regular single-SIM or dual-SIM solutions take several seconds or even tens of seconds to do network switch, which fails to meet the millisecond-level response requirements for autonomous driving.