Discuss combined attach, combined detach and combined tracking area update in LTE networks?
Combined attach, combined detach and combined tracking area update are mobility management procedures in LTE networks that involve both the EPS (Evolved Packet System) and the CS (Circuit Switched) domains. They are used to optimize the network resources and the user experience by reducing the signaling overhead and the latency.
• Combined attach: This procedure allows the UE (User Equipment) to attach to both the EPS and the CS domains simultaneously, by sending a single attach request message to the MME (Mobility Management Entity). The MME then forwards the request to the SGSN (Serving GPRS Support Node) and the MSC (Mobile Switching Center) via the SGs interface. The UE receives a single attach accept message from the MME, which contains the EPS and the CS parameters. This procedure saves the radio resources and the time that would be otherwise spent on separate attach procedures for each domain.
• Combined detach: This procedure allows the UE to detach from both the EPS and the CS domains simultaneously, by sending a single detach request message to the MME. The MME then forwards the request to the SGSN and the MSC via the SGs interface. The UE receives a single detach accept message from the MME. This procedure saves the radio resources and the time that would be otherwise spent on separate detach procedures for each domain.
• Combined tracking area update: This procedure allows the UE to update its location in both the EPS and the CS domains simultaneously, by sending a single tracking area update request message to the MME. The MME then forwards the request to the SGSN and the MSC via the SGs interface. The UE receives a single tracking area update accept message from the MME, which contains the EPS and the CS parameters. This procedure saves the radio resources and the time that would be otherwise spent on separate tracking area update procedures for each domain.
Therefore, combined attach, combined detach and combined tracking area update are significiant procedures for LTE networks, as they enable the UE to access and manage both the EPS and the CS domains efficiently and effectively.