UE Back-Off Timer and Session-AMBR for 5G Slice Congestion
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Solution Overview
Problem
The 5G System (5GS) faces challenges in implementing a method to manage the number of User Equipments (UEs) allowed for each network slice, which is essential for efficient network slicing in 5G networks.
Innovation Solution
A User Equipment (UE) is designed to transmit a PDU session establishment request message including an S-NSSAI and a PDU session ID, and receive a PDU session establishment accept message. The UE then configures a back-off timer and applies specific data rates to the PDU session based on the received Session-AMBR IE, and updates these settings upon receiving PDU session modification commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If network slicing is implemented in 5G systems, then service-specific network functions and characteristics can be provided, but management of the number of UEs per network slice becomes complex
Solution Approach 1:
The patent applies parameter changes by introducing Session-AMBR (Session Aggregate Maximum Bit Rate) as a controllable parameter for PDU sessions. The network can dynamically adjust the Session-AMBR value to control data rates for different UEs in network slices, enabling flexible resource management without increasing UE complexity. This resolves the contradiction by providing adaptability through parameter adjustment while keeping the UE device relatively simple.
Solution Approach 2:
The patent implements preliminary action by establishing PDU session templates with pre-configured Session-AMBR values during network slice setup. When UEs join network slices, they inherit these pre-configured parameters, eliminating the need for complex real-time negotiations and reducing UE management complexity while maintaining network slicing adaptability.
2Reliability
If back-off timer and data rate limiting are applied to control UE access, then network congestion can be managed, but UE configuration complexity increases
Solution Approach 1:
The patent applies universality by making the back-off timer and Session-AMBR configuration universal across all UEs in a network slice. Instead of configuring individual timers for each UE, the network sets a common Session-AMBR and back-off timer that applies to all UEs in the slice, reducing configuration complexity while maintaining reliable congestion control.
Solution Approach 2:
The patent implements feedback mechanisms where the network monitors PDU session establishment responses and adjusts Session-AMBR values and back-off timer settings based on network conditions. This automated feedback loop manages congestion effectively while minimizing manual configuration complexity for UEs.
Data Source
AI summary
A User Equipment (UE) comprises control circuitry and transmission and reception circuitry. The transmission and reception circuitry is configured to receive, from an Access and Mobility Management Function (AMF), a first configuration update command message including a rejected Network Slice Selection Assistance Information (NSSAI) including a Single Network Slice Selection Assistance Information for which a maximum number of UEs has been reached, a cause value indicating that the S-NSSAI is not available due to the maximum number of UEs being reached, and a back-off timer value for the S-NSSAI. The control circuitry is configured to start a timer with the back-off timer value for the S-NSSAI. The transmission and reception circuitry is further configured not to attempt to use the S-NSSAI while the back-off timer is running.