Always-on PDU Session Management with Retry Backoff
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Solution Overview
Problem
Current 5G network specifications lack clear guidance on managing always-on Protocol Data Unit (PDU) sessions, leading to resource wastage and increased power consumption when UE leaves the network, as frequent signaling requests are made despite disallowed sessions.
Innovation Solution
Introduction of a retry backoff mechanism in UE and a lifetime mechanism in the network to manage always-on PDU sessions, where UE waits before resending requests and network releases sessions if UE does not return within a configured time frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE continuously resends the PDU SESSION ESTABLISHMENT/MODIFICATION REQUEST message when the always-on PDU session is not allowed, then the UE can eventually establish the session, but the frequent signaling causes unnecessary power consumption and wastes network resources
Solution Approach 1:
The patent applies periodic action by introducing a retry backoff mechanism that specifies a time interval between repeated signaling attempts. The network responds with a 'retry backoff' indication that tells the UE to wait for a predetermined period before resend the PDU SESSION ESTABLISHMENT/MODIFICATION REQUEST message, transforming continuous signaling into periodic signaling with controlled intervals, thereby reducing power consumption while maintaining eventual session establishment capability
2Reliability
If the UE continuously resends the PDU SESSION ESTABLISHMENT/MODIFICATION REQUEST message when the always-on PDU session is not allowed, then the UE can eventually establish the session, but the frequent signaling wastes network resources
Solution Approach 1:
The patent applies periodic action by introducing a retry backoff mechanism that specifies a time interval between repeated signaling attempts. The network responds with a 'retry backoff' indication that tells the UE to wait for a predetermined period before resend the PDU SESSION ESTABLISHMENT/MODIFICATION REQUEST message, transforming continuous signaling into periodic signaling with controlled intervals, thereby reducing power consumption while maintaining eventual session establishment capability
3Adaptability or versatility
If the network maintains the always-on PDU session after the UE leaves the network, then the session remains available for the UE, but the network resources are wasted when the UE does not return
Solution Approach 1:
The patent applies preliminary action by introducing a lifetime mechanism that pre-configures a predetermined time period for session validity. When the UE leaves the network, the network starts a countdown timer for the always-on PDU session. If the UE does not return before the timer expires, the network automatically releases the session. This preliminary timing configuration ensures resources are released in a timely manner while still allowing the UE to return and resume service within the configured lifetime period
Data Source
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AI summary
A method of signaling enhancement for an always-on PDU session is provided. A User Equipment (UE) transmits a Non-Access Stratum (NAS) request message to a mobile communication network. The NAS request message includes an Always-on PDU Session Requested (APSR) Information Element (IE). The UE receives a NAS response message including an Always-on PDU Session Indication (APSI) IE from the mobile communication network. The APSI IE includes a time length indicator. In response to the APSI IE indicating that the always-on PDU session is not allowed, the UE starts a timer based on the time length indicator and retransmits the NAS request message to the mobile communication network when the timer expires.