The UE is RRC connected.During the HO:The radio link is released from the eNodeB 1 and re-established on the
eNodeB 2The Control plane is switched to the eNodeB 2 and the MMEThe User plane is switched to the eNodeB 2 and the S-GW
The Intra-e-UTRAN-Access Mobility Support for UEs in ECM-CONNECTED handles all necessary steps for relocation/handover procedures, like processes that precede the final HO decision on the source network side (control and evaluation of UE and eNB measurements taking into account certain UE specific area restrictions), preparation of resources on the target network side, commanding the UE to the new radio resources and finally releasing resources on the (old) source network side.It contains mechanisms to transfer context data between evolved nodes, and to update node relations on C-plane and U-plane.
What is Intra E-UTRAN Handover in LTE?
Intra E-UTRAN Handover in LTE refers to the process of transferring an ongoing connection from one cell (evolved NodeB or eNB) to another within the same Evolved Universal Terrestrial Radio Access Network (E-UTRAN) system. This type of handover is typically used when the User Equipment (UE) moves between cells in the same network, ensuring uninterrupted service.
Steps in Intra E-UTRAN Handover
- 1. Handover Decision: The source eNB continuously monitors the UE’s signal quality. If the signal quality degrades or if the UE moves closer to another eNB, the source eNB decides that a handover is required.
- 2. Handover Request: The source eNB sends a handover request to the target eNB, including information about the UE’s connection and its resource needs.
- 3. Target eNB Preparation: The target eNB prepares to accept the UE’s connection by configuring the necessary radio resources. It may also involve adjusting parameters like frequency and power control to ensure a smooth handover.
- 4. Handover Command: Once the target eNB is ready, the source eNB sends a handover command to the UE, instructing it to begin communication with the target eNB.
- 5. Data Forwarding: The UE establishes a new connection with the target eNB, and the user data traffic is forwarded to the target eNB. The source eNB may forward buffered data to the target eNB during the transition to avoid data loss.
- 6. Handover Completion: Once the handover is successfully completed, the target eNB sends a handover completion message to the source eNB. The source eNB then releases the resources previously allocated to the UE.
Types of Intra E-UTRAN Handover
- Hard Handover: In a hard handover, there is a brief interruption of the connection while the UE transitions from one cell to another. This type of handover is typically used in LTE.
- Soft Handover: Although more common in earlier generations of mobile networks (like WCDMA), soft handover involves maintaining simultaneous connections to multiple cells during the transition. LTE generally uses hard handover.
Why Intra E-UTRAN Handover Matters
Intra E-UTRAN Handover is critical for ensuring seamless mobility in LTE networks. As users move from one cell to another, this process ensures that data transmission is uninterrupted, preventing dropped calls or interrupted internet sessions. Efficient handover management helps maintain service quality and ensures a smooth user experience, especially in high-speed mobile scenarios.