Sign in Subscribe

Path Switch Request

Last updated on 


A Path Switch Request is a signaling procedure in mobile communication networks, such as Long-Term Evolution (LTE) and 5G, used to request the switching of data traffic from one radio access path to another. This procedure is typically used when a User Equipment (UE) is configured for Dual Connectivity or similar features, allowing it to simultaneously connect to multiple cell sites or radio access technologies for improved data throughput and reliability. Here's a detailed technical explanation of the Path Switch Request procedure:

1. Triggering Event:

  • The Path Switch Request procedure is initiated when there's a need to switch the data traffic of a UE from one access path (e.g., a primary cell) to another (e.g., a secondary cell) to optimize resource utilization or improve network performance.

2. Network Decision:

  • The decision to initiate a path switch may be made by the network's Radio Resource Control (RRC) or Mobility Management Entity (MME) in LTE, or the Access and Mobility Management Function (AMF) in 5G. This decision is based on factors such as UE mobility, network load, and quality of service (QoS) requirements.

3. Generation of Path Switch Request:

  • When the network decides that a path switch is necessary, it generates a Path Switch Request message. This message contains information about the switch, including the target access path or cell, its capabilities, and any necessary parameters for the switch.

4. Contents of Path Switch Request:

  • The Path Switch Request message typically includes the following information:
  • Target Cell Information: Identifies the target cell or access path to which the UE should switch.
  • Parameters for the Switch: May include details about the type of handover or path switch (e.g., handover type, switching cause).
  • Context Information: If necessary, context information about the UE's current state and session data may be included to facilitate a smooth handover.

5. Transmission to the UE:

  • Once the Path Switch Request message is generated, it is transmitted to the UE over the current access path (e.g., the primary cell).

6. UE Acknowledgment:

  • Upon receiving the Path Switch Request, the UE processes the message and acknowledges it, confirming that it is ready to perform the path switch.

7. Activation of Target Path:

  • After receiving the acknowledgment from the UE, the network activates the target access path (e.g., the secondary cell) and configures it to be ready for data transfer.

8. Data Transfer Switch:

  • With the target path activated and ready, the network initiates the switch of data traffic from the current access path to the target path. This is done while ensuring minimal disruption to ongoing data sessions.

9. UE Confirmation of Switch:

  • The UE confirms the successful path switch once it begins receiving data on the new access path. This confirmation may be sent as an acknowledgment message back to the network.

10. Procedure Completion: - The Path Switch Request procedure is considered complete when both the network and the UE have confirmed the successful switch, and data transfer is occurring on the new access path.

Path Switch Requests are crucial for enhancing the performance and efficiency of mobile networks, especially in scenarios where Dual Connectivity or multi-connectivity is employed to provide seamless coverage and improved data rates. They ensure that data traffic is routed through the most suitable access path based on network conditions and UE requirements.