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RRC Connection Reestablishment Reject

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In LTE (Long-Term Evolution) and 5G mobile communication networks, the RRC (Radio Resource Control) Connection Reestablishment Reject is a message sent by the network to the User Equipment (UE) to reject a request for reestablishing an RRC connection. This message is a part of the RRC Connection Reestablishment procedure, which is used to reestablish the RRC connection after an interruption or loss of the existing connection. Let's explore the technical details of the RRC Connection Reestablishment Reject procedure:

  1. Trigger for RRC Connection Reestablishment:The need for reestablishing the RRC connection arises when there is a loss of the existing RRC connection due to factors like handover failure, radio link failure, or other network issues.
  2. UE RRC Connection Reestablishment Request:The UE initiates the RRC Connection Reestablishment procedure by sending an RRC Connection Reestablishment Request message to the network, indicating the desire to reestablish the connection.
  3. Reestablishment Request Parameters:The RRC Connection Reestablishment Request includes important parameters such as UE identity, security parameters, and information about the previous RRC connection.
  4. Network Processing of Reestablishment Request:The network processes the received RRC Connection Reestablishment Request, validates the parameters, and checks if the reestablishment is feasible.
  5. Handover Preparation:If a handover is involved, the network prepares for the handover operation to ensure a smooth transition to a new cell or node.
  6. Validation of Request:The network validates the RRC Connection Reestablishment Request based on the context and security information provided. This validation ensures that the request is genuine and authorized.
  7. RRC Connection Reestablishment Reject Generation:If the request cannot be accepted or validated, the network generates an RRC Connection Reestablishment Reject message, indicating the rejection of the reestablishment request.
  8. Rejection Cause:The message includes a cause parameter that specifies the reason for the rejection, such as authentication failure or invalid security credentials.
  9. Transmission to UE:The RRC Connection Reestablishment Reject message is transmitted from the network to the UE over the appropriate control channels.
  10. UE Processing of Reestablishment Reject:The UE processes the received RRC Connection Reestablishment Reject message, interprets the rejection cause, and takes appropriate actions based on the rejection.
  11. Handling the Rejection:The UE adjusts its internal parameters and may initiate alternative procedures, such as reattempting the RRC connection establishment or triggering a new registration attempt.

The RRC Connection Reestablishment Reject is an important mechanism that allows the network to reject reestablishment attempts that cannot be authorized or validated. This ensures the security and proper functioning of the RRC connection reestablishment procedure in LTE and 5G mobile networks.