UE Registration Retry Logic for IMS Subscription Errors

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Solution Overview

Problem

Existing user equipment (UE) procedures for handling subscription errors during registration status in Wi-Fi calling are suboptimal, leading to continuous registration failures and network bandwidth reduction due to unresolved issues like missing 911 location and high network congestion, causing potential network outages.

Innovation Solution

The UE is configured to transmit a predetermined number of registration requests before halting further attempts and to wait increasingly longer periods between attempts, based on the number of previous requests, to allow recoverable issues to resolve and conserve network bandwidth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE immediately retries registration requests after failure, then the registration success rate may improve, but network bandwidth consumption increases and congestion worsens

Engineering Contradiction:
Improveregistration success rateVSAvoidnetwork bandwidth consumption
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements periodic retry actions with exponentially increasing intervals between attempts. After each failed registration request, the UE waits for a time period that doubles with each subsequent retry (e.g., 1 second, 2 seconds, 4 seconds, 8 seconds, 16 seconds, 32 seconds, 64 seconds, 128 seconds, 256 seconds, 512 seconds, 1024 seconds, 2048 seconds). This periodic action with expanding intervals allows registration attempts to succeed while controlling network bandwidth consumption by spacing out requests.

Inventive Principle:
Principle #19Periodic action

2Reliability

If the UE transmits multiple registration requests to handle recoverable issues like network congestion, then service restoration is enabled, but continuous transmission during high congestion causes further network overload

Engineering Contradiction:
Improveservice restoration capabilityVSAvoidnetwork congestion
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies beforehand cushioning by pre-establishing a maximum retry limit (12 attempts) and exponentially increasing wait periods before each retry. This cushioning mechanism prevents the UE from continuously transmitting registration requests during network congestion, allowing the network to recover while ensuring service restoration capability is maintained within reasonable bounds.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Loss of energy

If the UE waits longer between registration attempts, then network congestion is reduced and bandwidth is conserved, but the time to restore service increases

Engineering Contradiction:
Improvenetwork bandwidth conservationVSAvoidservice restoration time
Core Design Contradiction:
Loss of energyVSLoss of time

Solution Approach 1:

The patent implements dynamics by making the wait period between registration attempts adaptive rather than fixed. The wait time dynamically increases with each retry attempt following an exponential pattern (1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048 seconds). This dynamic adjustment conserves network bandwidth during high congestion while progressively reducing service restoration time as the network condition improves or the retry limit is approached.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3527015B1Error handling during IMS subscription for registration status
Publication Date: 2021.11.10 T MOBILE US INC
  • EP3527015B1 patent drawingFigure 1
  • EP3527015B1 patent drawingFigure 2
  • EP3527015B1 patent drawingFigure 3

AI summary

In instances where a user equipment (UE) encounters an issue during an attempt to subscribe for registration status, the UE is configured with improved logic for handling the encountered issue. For instance, the UE may transmit a number of subsequent registration requests up to a predetermined number of registration requests before ultimately refraining from transmitting any additional registration requests. The UE may also wait until a lapse of a period of time before transmitting any next registration request and/or subscription request, thereby giving the carrier network sufficient time to resolve any recoverable issues before transmitting a next registration request and/or subscription requests. On subsequent iterations, the time period may be incremented to provide longer and longer wait times before transmitting subsequent registration requests and/or subscription requests.