Inter-PLMN Discovery in D2D Communication

The patent segments the discovery monitoring process by dividing PLMNs into different priority levels (high priority and low priority). The UE monitors high priority PLMNs continuously while monitoring low priority PLMNs only when specific conditions are met (such as when no high priority PLMN is available or when discovery opportunities are detected). This segmentation reduces overall monitoring activity and thus battery power consumption while maintaining inter-PLMN discovery capability.

The patent applies preliminary action by pre-configuring priority levels for different PLMNs before the actual discovery process. The UE is provided with priority information about different PLMNs in advance, which allows it to automatically determine the monitoring order and reduce the complexity of real-time decision-making during discovery operations. This pre-configuration simplifies the monitoring process while maintaining comprehensive inter-PLMN discovery capability.

The patent implements dynamics by making the discovery monitoring behavior adaptive based on the UE's current state and available resources. When the UE is in connected state with good signal quality, it prioritizes communication with the serving cell and reduces or suspends inter-PLMN discovery monitoring. When signal quality deteriorates or the UE is in idle state, it increases discovery monitoring activity. This dynamic adjustment ensures that communication reliability with the serving cell is maintained while still enabling inter-PLMN discovery when appropriate.