NB-IoT UE RRC Re-establishment Without Handover

Solution Overview

Problem

Narrowband Internet of Things (NB-IoT) user equipment (UE) devices do not support handover operations in an RRC connected state, leading to potential radio link failures and prolonged recovery times when moving between cells.

Innovation Solution

A method for NB-IoT UE to perform RRC connection re-establishment procedures based on measurement results, reselecting neighboring cells with superior signal quality and transmitting RRC connection re-establishment request messages to the network, even without AS security activation, to maintain continuous communication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If NB-IoT UE does not support handover function to operate with low power, then power consumption is reduced, but radio link failure occurs when moving between cells and recovery time increases

Engineering Contradiction:

Improvepower consumptionVSAvoidradio link failure

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The UE performs measurement of neighboring cells in advance and stores measurement results before handover is needed. When moving to a new cell, the UE can quickly initiate RRC connection re-establishment using pre-stored measurement information, avoiding the need for real-time measurements during handover and reducing recovery time while maintaining low power operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The UE autonomously determines whether to perform RRC connection re-establishment by comparing stored measurement results with re-establishment conditions, without requiring network control or handover functionality. This self-service approach allows the UE to maintain connectivity during cell movement independently, improving reliability without adding complex network-dependent handover procedures.

Inventive Principle:

Principle #25Self-service

2Device complexity

If NB-IoT UE does not support handover function to operate with low power, then device complexity is reduced, but recovery time increases when radio link failure occurs

Engineering Contradiction:

Improvehandover functionVSAvoidrecovery time

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The UE performs measurement of neighboring cells in advance and stores measurement results before handover is needed. When moving to a new cell, the UE can quickly initiate RRC connection re-establishment using pre-stored measurement information, avoiding the need for real-time measurements during handover and reducing recovery time while maintaining low power operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the operational parameters by allowing RRC connection re-establishment without AS security activation, which is traditionally required. This parameter change enables faster re-establishment procedure while maintaining security through alternative mechanisms, reducing recovery time without significantly increasing device complexity.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If RRC connection re-establishment is performed without AS security activation to maintain continuous communication, then communication reliability is improved, but security may be compromised

Engineering Contradiction:

Improvecommunication continuityVSAvoidsecurity risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the operational parameters by allowing RRC connection re-establishment without AS security activation, which is traditionally required. This parameter change enables faster re-establishment procedure while maintaining security through alternative mechanisms, reducing recovery time without significantly increasing device complexity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The measurement result storage and comparison mechanism acts as an intermediary that enables the UE to make informed decisions about when to initiate re-establishment. By using pre-stored measurement information, the UE can trigger re-establishment proactively before radio link failure occurs, maintaining communication continuity while using the measurement data as a security-aware decision basis.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10820363B2Method for performing RRC connection re-establishment procedure and device supporting the same

Publication Date: 2020.10.27 LG ELECTRONICS INC

AI summary

Proposes are: a method for performing a radio resource control (RRC) connection re-establishment procedure by a user equipment (UE) in a wireless communication system, and a device supporting the same. The method includes: entering an RRC connected state; receiving an RRC connection re-establishment condition; determining whether the RRC connection re-establishment condition is satisfied based on a measurement result; and performing an RRC connection re-establishment procedure when the RRC connection re-establishment condition is satisfied, wherein the UE is a UE not supporting a handover in the RRC connected state.