Handovers are a crucial aspect of LTE networks, as they ensure seamless connectivity as mobile devices move within the network.
Types of Handover in LTE
What are the different types of handover in LTE?
Description: Intra-frequency handovers occur when a mobile device moves within the same frequency band and connects to a different cell but on the same frequency.
Use Cases: This type of handover is typically used for small-scale cell deployments, such as within a city or a building, to maintain connectivity as the user moves around.
Description: Inter-frequency handovers are employed when a mobile device moves from one frequency band to another, typically from one carrier frequency to another.
Use Cases: This type of handover is essential for LTE networks operating on multiple frequency bands, allowing for seamless transitions between them as needed. It’s especially useful in scenarios where different frequency bands offer varying coverage and capacity.
Inter-RAT (Radio Access Technology) Handover:
Description: Inter-RAT handovers occur when a mobile device switches from LTE to a different radio access technology, such as GSM or UMTS (3G).
Use Cases: This type of handover is crucial for backward compatibility and roaming scenarios where LTE coverage is not available, and the device needs to connect to older 2G or 3G networks.
Description: Soft handover is a seamless handover technique where a mobile device is connected to multiple cells simultaneously. This allows for a smoother transition as the device can receive data from multiple cells during the handover.
Use Cases: Soft handover is particularly useful in scenarios with high mobility, as it reduces the chances of call drops and maintains a high-quality connection.
Description: Hard handover, also known as break-before-make, involves disconnecting from the current cell before connecting to a new cell. There is a brief interruption in the connection during this process.
Use Cases: Hard handovers are typically used in scenarios where soft handovers are not feasible due to resource limitations or network design considerations.
Description: Fast handover techniques aim to minimize the duration of the handover process, reducing the interruption in data transmission.
Use Cases: Fast handovers are crucial for real-time applications like voice over LTE (VoLTE) and video calls, where even a short interruption can be noticeable.
Description: In this type of handover, the mobile device establishes a connection with the target cell before disconnecting from the source cell. This ensures a smoother transition.
Use Cases: Make-before-break handovers are commonly used in LTE networks to reduce the impact of handovers on user experience, especially for data-intensive applications.
Idle Mode Handover:
Description: Idle mode handovers occur when the mobile device is not actively engaged in a data or voice call. The handover process takes place while the device is in an idle state.
Use Cases: This type of handover is efficient for maintaining network connectivity when the device is not actively in use, helping to optimize network resources.
Connected Mode Handover:
Description: Connected mode handovers take place when the mobile device is actively transmitting data or engaged in a voice call. Ensuring minimal disruption during these handovers is crucial.
Use Cases: Connected mode handovers are essential for maintaining the quality of ongoing voice calls and data sessions.
Description: S1 handovers occur between LTE eNodeBs (base stations) within the same E-UTRAN (Evolved Universal Terrestrial Radio Access Network).
Use Cases: This type of handover is used to optimize network resources and balance traffic load between eNodeBs.
Description: X2 handovers take place between two neighboring eNodeBs without involving the core network (EPC – Evolved Packet Core). It is used for load balancing and enhancing network efficiency.
Use Cases: X2 handovers help in offloading traffic from congested cells to less congested ones, improving overall network performance.
The Handover is the process of transferring an ongoing call or data session from one cell connected to the core network to another
- It is transparent for the end user
- It is network controlled and UE assisted
- The 3GPP defines handover:
- Intra e-UTRAN
- Inter RAT with 3GPP technologies (GSM, WCDMA)
- Inter RAT with non-3GPP technologies (CDMA2000, HRPD)
LTE networks employ various types of handovers to ensure uninterrupted connectivity and seamless transitions for mobile devices as they move within the network. These handover techniques are essential for delivering a consistent user experience and optimizing network resources in a dynamic wireless environment.