Handover, also known as handoff, is a critical process in LTE (Long-Term Evolution) networks that involves the seamless transfer of a mobile device or User Equipment (UE) from one cell or radio access node to another. Handovers are essential to maintain continuous and uninterrupted communication as a UE moves through the network. There are several types of handovers in LTE, each designed to address specific scenarios and optimize network performance. Let’s explore the detailed explanation of the types of handovers in LTE:
1. Intra-frequency Handover:
- Description:
- Intra-frequency handover occurs when a UE moves within the same frequency band and remains connected to the same eNodeB (Evolved NodeB).
- Scenario:
- This type of handover is typically employed when a UE transitions between cells within the same LTE carrier frequency.
2. Inter-frequency Handover:
- Description:
- Inter-frequency handover takes place when a UE moves between cells that operate on different carrier frequencies.
- Scenario:
- This type of handover is useful in scenarios where the network employs multiple carrier frequencies, and a UE needs to transition between them.
3. Inter-RAT (Radio Access Technology) Handover:
- Description:
- Inter-RAT handover occurs when a UE moves between LTE and other radio access technologies, such as GSM (Global System for Mobile Communications) or UMTS (Universal Mobile Telecommunications System).
- Scenario:
- This type of handover is necessary when a UE transitions between LTE coverage and areas served by legacy technologies.
4. Soft Handover:
- Description:
- Soft handover involves a brief overlap during which a UE is connected to both the source and target cells simultaneously.
- Scenario:
- Soft handover is advantageous in situations where a UE is on the border between cells, ensuring continuous connectivity without abrupt interruptions.
5. Hard Handover:
- Description:
- Hard handover involves a brief interruption of the connection with the source cell before establishing a connection with the target cell.
- Scenario:
- Hard handover is suitable for scenarios where the UE is moving between cells, and a brief interruption in connectivity is acceptable.
6. Make-Before-Break Handover:
- Description:
- Make-before-break handover establishes a connection with the target cell before disconnecting from the source cell.
- Scenario:
- This type of handover minimizes the risk of call drops and is beneficial in scenarios where network conditions permit early establishment of the target connection.
7. Handover to Untrusted Target:
- Description:
- Handover to an untrusted target refers to scenarios where a UE moves to a cell with potentially lower security or unfamiliar network conditions.
- Scenario:
- This type of handover requires careful authentication and security measures to ensure the integrity of the communication.
8. X2 Handover:
- Description:
- X2 handover involves direct communication between eNodeBs without involving the core network.
- Scenario:
- X2 handover is efficient for quick handovers between neighboring eNodeBs, reducing latency and enhancing overall performance.
Conclusion:
The various types of handovers in LTE networks are designed to address different mobility scenarios and optimize the transition of UEs between cells or radio access technologies. Intra-frequency, inter-frequency, and inter-RAT handovers cater to different network configurations, while soft and hard handovers provide options for managing connectivity during transitions. Make-before-break handovers enhance continuity, and handovers to untrusted targets require careful security considerations. X2 handovers facilitate direct communication between eNodeBs for efficient handover processes. The diversity of handover types in LTE reflects the adaptability of the network to different mobility scenarios, contributing to a seamless and robust mobile communication experience.