UE Session Retry Restriction for Network Signaling Optimization
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Solution Overview
Problem
In mobile communication systems, UE retry signaling due to rejected EPS session management messages leads to inefficient traffic, consuming network resources unnecessarily, as UEs aggressively retry rejected requests without adequate conditions for change, making it difficult for operators to diagnose issues and manage network overload.
Innovation Solution
Implementing a retry restriction mechanism in UEs that requires specific conditions, such as a retry wait timer or detection of a retry trigger event, before retrying session management requests rejected due to operator-determined barring or other specific cause values, thereby preventing excessive signaling and allowing operators to monitor issues effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE aggressively retries rejected session management requests, then the UE can potentially establish successful connections, but network resources are consumed unnecessarily and operators cannot effectively diagnose issues
Solution Approach 1:
The network performs preliminary actions by sending rejection messages with cause values and optional retry wait times before the UE attempts retries. This allows the network to pre-determine whether retries should be restricted, preventing unnecessary network resource consumption while still allowing legitimate connection attempts
Solution Approach 2:
The system implements feedback mechanisms where the network provides cause values and retry wait time information to the UE in rejection messages. The UE uses this feedback to adjust its retry behavior, stopping retries when cause values indicate permanent failures or when retry wait times expire, thereby optimizing network resource usage
2Speed
If UE immediately retries rejected requests, then connection establishment may be faster, but network overload increases and issue diagnosis becomes difficult
Solution Approach 1:
The retry mechanism is made dynamic by allowing the retry wait time to vary based on the cause value. For temporary failures, shorter or zero wait times allow quick retries, while for permanent failures, longer wait times or restrictions prevent wasteful retries. This dynamic adjustment optimizes both connection speed and network efficiency
Solution Approach 2:
The system changes the parameter of retry wait time based on the cause value received in rejection messages. Different cause values map to different retry behaviors (e.g., cause value 32 allows immediate retry, while cause value 33 may impose longer waits). This parameter adaptation enables the system to balance connection speed with network resource efficiency
3Productivity
If UE retries without conditions, then connection attempts are made quickly, but excessive signaling occurs and operators cannot monitor issues effectively
Solution Approach 1:
The retry wait time parameter acts as an intermediary between the UE and the network, mediating the retry behavior. By controlling when retries occur through this intermediate parameter, the system reduces excessive signaling while maintaining effective connection attempts, and allows operators to monitor retry patterns for issue diagnosis
Data Source
Figure 1
Figure 2A~2B
Figure 3A
AI summary
A method of operating a user equipment (UE) in a wireless communications network includes sending, from the UE to a first network element, a. first packet service session management request message indicating a request of a first session management service type for at least one of establishing a new packet data session or modifying an existing packet data session, the first packet service session management request message being sent towards a first access point name (APN); receiving, at the UE, a rejection message, the rejection message indicating the request of the first session management service type has been rejected; and performing a retry operation after receiving the rejection message, the retry operation including sending, from the UE, a second packet service session management request message of the first session management service type towards the first APN, the retry operation being prevented by the UE such that the retry operation is not performed by the UE until after at least one of, an expiration of a retry timer of the UE, or detection, at the UE, of a retry trigger event.