Special Uplink Subframe for Seamless Handover Latency Reduction

The target base station performs channel estimation and timing synchronization using reference signals transmitted by the UE during the handover preparation phase, before the actual handover execution. This preliminary action allows the target base station to have timing advance information ready, eliminating the need for UE to cease transmissions during handover.

The patent enables continuous uplink data transmissions from the UE during handover by allowing the target base station to decode transmissions using previously acquired channel estimates. The UE maintains its uplink transmission continuity while the target base station performs synchronization in the background using reference signals.

Reference signals act as an intermediary mechanism that carries timing information from the UE to the target base station. These dedicated reference signals enable the target base station to acquire uplink timing and perform channel estimation without disrupting the UE's continuous data transmissions.

The patent changes the transmission parameters of reference signals during handover, specifically increasing reference signal density or power in the uplink direction. This parameter change ensures that the target base station can reliably acquire timing information even while the UE maintains continuous data transmissions at normal power levels.