What is the process of handover in LTE?
Let me explain to you the process of handover in LTE, which plays a key role in ensuring seamless connectivity and service continuity as you move from one cell to another while using your mobile device. If you’ve read our previous discussions about LTE networks, you’ll already know that LTE is designed for high-speed mobile communication. However, a crucial aspect of mobile communication is the ability to maintain a stable connection as users move across different cell towers or areas. This is where handover comes into play.
In LTE, handover refers to the process by which a mobile device (User Equipment or UE) moves from one base station (eNodeB) to another while maintaining its ongoing data or voice session. Handover ensures that you don’t experience service interruptions when you are on the move. Whether you’re driving, walking, or traveling in any way, LTE networks manage handover so that you stay connected without any noticeable loss of signal or service quality.
Now, let’s take a deeper dive into how the handover process works in LTE.
When you move away from one eNodeB’s coverage area and enter another one, the eNodeB starts the handover process to make sure that your device is connected to the new base station. But how does this process occur? Here’s a simplified breakdown:
- Preparation Phase: The UE continuously monitors its signal strength and quality in its current cell. If the signal from the serving cell becomes weak and the signal from a neighboring cell (eNodeB) is stronger, the UE triggers a measurement report to the serving eNodeB. This helps the network decide if a handover is necessary.
- Decision Phase: Based on the measurement reports received from the UE, the serving eNodeB or the Mobility Management Entity (MME) evaluates whether a handover is required. If the conditions are favorable, the decision to handover the connection to a new eNodeB is made.
- Preparation of the Target eNodeB: The target eNodeB, which is the next base station to take over the UE’s connection, prepares to receive the UE. This involves allocating resources, updating the UE’s context, and making sure the handover process can happen smoothly.
- Execution Phase: Once everything is ready, the handover command is sent from the serving eNodeB to the UE, instructing it to switch to the target eNodeB. The target eNodeB then establishes a communication link with the UE, allowing it to continue its session. In this phase, the UE switches to the new base station and disconnects from the old one.
- Completion Phase: After the handover is completed successfully, the serving eNodeB releases the resources it had allocated to the UE. The UE is now fully connected to the new eNodeB, and its data or voice session continues seamlessly.
The entire process is typically very quick, and you as a user may not even notice the handover happening. This is because LTE networks are designed to handle these transitions efficiently. However, there are different types of handovers that might be triggered depending on the specific network conditions and requirements. These include:
- Intra-eNB Handover: This type of handover occurs when both the source and target eNodeBs belong to the same base station, which makes the handover process relatively simple.
- Inter-eNB Handover: In this case, the handover happens between two eNodeBs belonging to different base stations, making it slightly more complex as it requires coordination between the two stations.
- Inter-RAT Handover: This handover involves a change in Radio Access Technology (RAT), such as transitioning from LTE to 3G or 2G. This type of handover is more complex as it requires signaling between LTE and the older networks.
As previously discussed in articles related to LTE architecture and mobility management, the handover process is a critical feature that supports uninterrupted service, especially when you’re moving between coverage areas. It’s what makes sure that you stay connected even if you’re traveling between different cells or base stations.
To sum up, handover is a crucial process in LTE that ensures seamless mobility for users. It ensures that no matter where you go, you can continue to use data or voice services without interruptions, making your experience on LTE networks smooth and reliable.