Random Access for Secondary Cells in Carrier Aggregation

The patent segments the uplink synchronization management by introducing TA groups that partition multiple cells into distinct timing advance groups. Each TA group can be independently managed with its own timing advance value, allowing the system to handle multiple cells without requiring complex individual management of each cell's synchronization, thus resolving the contradiction between improved throughput and increased management complexity

The patent applies universality by enabling a single timing advance value to serve multiple cells within the same TA group. This multi-functional approach allows one TA value to maintain synchronization across multiple cells, reducing the overall number of synchronization parameters needed and simplifying management while maintaining high system throughput

The patent applies preliminary action by pre-configuring TA group information and random access parameters for secondary cells before the UE needs to perform random access. The eNB provides RA parameters and TA group configurations in advance through RRC signaling, so when random access is needed, the UE can immediately execute the procedure without requiring complex real-time decision-making, thus ensuring synchronization reliability while limiting procedure complexity

The patent introduces TA groups as an intermediary concept that mediates between the UE and multiple secondary cells. Rather than requiring direct individual synchronization management for each scell, the TA group acts as an intermediate layer that groups cells together, allowing simplified random access procedures to maintain synchronization across multiple cells simultaneously