Resetting Downlink HARQ for Multicast Reception

The patent applies preliminary action by resetting the MAC entity and flushing the HARQ soft buffer before receiving new multicast data in the target cell. This preliminary reset operation prevents invalid data from the source cell from interfering with new data reception, ensuring that the HARQ process starts fresh with valid data from the target cell. The reset is triggered by receiving an RRC release message with suspend configuration or by detecting cell reselection, which prepares the system in advance for continuous multicast service.

The patent applies parameter changes by modifying the state of the MAC entity and HARQ soft buffer through reset operations. Specifically, the system changes the validity parameter of the HARQ soft buffer from 'valid' to 'invalid' upon cell reselection, triggering a flush operation. This parameter change approach simplifies management by using a clear state transition mechanism rather than complex data validation logic, making the system easier to manage while maintaining high data processing accuracy.

The patent applies the taking out principle by extracting and removing data from the HARQ soft buffer when cell reselection is detected. By flushing the buffer contents, the system separates the old data from the new data reception process. This extraction operation ensures that only valid data from the target cell is processed, preventing mixing of data from source and target cells while maintaining continuous multicast service through rapid rebuffering from the new cell.