CIoT UE Redirection Handling for Unsupported RAT Reject Causes

Solution Overview

Problem

Existing CIoT devices face inefficiencies such as delays in obtaining normal services, resource wastage, excessive power consumption, inconsistent UE behavior, and UE capability mismatches leading to procedural failures, particularly when redirected to unsupported Radio Access Technologies (RATs) due to lack of defined actions in 3GPP specifications.

Innovation Solution

Enhanced NAS procedures in UE and network entities to handle resource management, including handling reject cause #31 as an abnormal case, setting active flags appropriately, indicating changes in CIoT optimization preferences, and optimizing UE behavior to reduce signaling overhead and improve procedural efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the network redirects the UE to a core network using reject cause #31, then core network redirection is achieved, but the UE behavior becomes undefined when the UE does not support the redirected RAT

Engineering Contradiction:

Improvecore network redirection reliabilityVSAvoidUE behavior definition

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent inverts the traditional approach by having the UE proactively indicate its RAT support capability to the network before redirection is attempted. Instead of the network blindly redirecting and the UE reacting, the UE's capability information is used by the network to determine whether to send reject cause #31, thus avoiding the undefined behavior scenario entirely.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent applies preliminary action by having the UE send an indication message about its RAT support capability before the network performs redirection. This advance notification allows the network to make informed decisions about redirection, preventing the situation where the UE receives redirection to an unsupported RAT.

Inventive Principle:

Principle #10Preliminary action

2Loss of time

If the UE enters LIMITED SERVICE state after receiving reject cause #31, then the UE stops attempting registration, but the UE may become stuck in this state even when it can avail normal services

Engineering Contradiction:

Improveregistration attempt timeVSAvoidservice availability

Core Design Contradiction:

Loss of timeVSProductivity

Solution Approach 1:

The patent makes the UE's service state dynamic by introducing a mechanism where the UE can transition out of LIMITED SERVICE state when it receives an indication that the network no longer requires redirection. The UE monitors for such indications and automatically resumes normal service operations, creating a flexible state transition system rather than a static limited service state.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by having the network send indications to the UE about whether redirection is still required. This feedback loop allows the UE to adjust its service state accordingly - remaining in LIMITED SERVICE when redirection is needed, but transitioning back to normal service when the network indicates redirection is no longer necessary.

Inventive Principle:

Principle #23Feedback

3Object-affected harmful factors

If the UE disables N1 mode capability upon receiving reject cause #31, then the UE avoids using unsupported RAT, but the UE cannot use normal services even when the network supports them

Engineering Contradiction:

Improveunsupported RAT usageVSAvoidservice access capability

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent applies preliminary action by having the UE send an indication message about its RAT support capability before the network performs redirection. This advance notification allows the network to make informed decisions about redirection, preventing the situation where the UE receives redirection to an unsupported RAT.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent makes the UE's service state dynamic by introducing a mechanism where the UE can transition out of LIMITED SERVICE state when it receives an indication that the network no longer requires redirection. The UE monitors for such indications and automatically resumes normal service operations, creating a flexible state transition system rather than a static limited service state.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12490220B2Methods, user equipment, and network entity for handling resource in wireless network

Publication Date: 2025.12.02 SAMSUNG ELECTRONICS CO LTD

AI summary

Embodiments disclosed herein relate to methods for handling a resource in a wireless network by a UE 100. The method includes receiving a reject cause message from a network entity. The UE does not support a redirected radio access technology (RAT) indicated in the reject cause message. Further, the method includes considering the reject cause message to represent an abnormal case and performing at least one action based on the abnormal case. The method can be used for enabling enhanced NAS procedure in CIoT devices. The method can also be used to indicate the change in support of CP/UP preference when both CP and UP CIoT optimization are supported, so as to reduce the signalling overhead in the wireless network, improve the UE behavior and NAS procedural efficiencies.