Idle Mode SS Identity for 5G NR State Transitions

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Solution Overview

Problem

In 5G New Radio (NR) wireless communication networks, there is a lack of mechanisms to avoid inter gNB mobility and double context moves during state transitions between connected and idle states, leading to unnecessary signaling and inefficiencies.

Innovation Solution

The implementation of methods in wireless devices and nodes to store and monitor idle mode synchronization signal identifiers, allowing seamless transitions between active and idle states, including obtaining and storing identifiers of idle mode synchronization signals of source and target nodes during handovers, and reentering idle mode to monitor these signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the UE transitions to idle mode without being informed of the idle mode SS identity, then the UE can perform cell reselection, but it may reselect to a cell belonging to a different gNB causing inter-gNB mobility and double context moves

Engineering Contradiction:

Improvecell reselection capabilityVSAvoidnetwork stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The network performs preliminary action by informing the UE of the idle mode SS identity before the UE transitions to idle mode. This advance notification ensures that when the UE enters idle mode and performs cell reselection, it can prioritize cells with the matching SS identity, thereby preventing inter-gNB mobility and double context moves while maintaining cell reselection capability

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If the UE performs measurements and sends reports upon resuming RRC connection, then mobility can be managed, but unnecessary signaling occurs every state transition creating ping-pong effects

Engineering Contradiction:

Improvemobility managementVSAvoidsignaling overhead

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The invention implements feedback mechanism where the network provides the UE with the idle mode SS identity before state transition. This feedback enables the UE to make informed cell reselection decisions without needing to perform extensive measurements and send reports upon RRC connection resumption, thereby reducing signaling overhead and preventing ping-pong effects while maintaining mobility management

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If the network uses different beamforming configurations in connected mode versus idle mode, then coverage optimization is achieved, but the UE cannot determine which cell to camp on when transitioning to idle mode

Engineering Contradiction:

Improvecoverage optimizationVSAvoidcell identification information

Core Design Contradiction:

Manufacturing precisionVSLoss of information

Solution Approach 1:

The idle mode SS identity serves as an intermediary that bridges the gap between connected mode and idle mode operations. The network provides this identity information to the UE before state transition, enabling the UE to identify and camp on the correct cell in idle mode despite different beamforming configurations being used in connected mode, thereby preventing loss of cell identification information

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10887807B2Methods to inform UE of idle mode SS identity

Publication Date: 2021.01.05 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

In one aspect, a method in a wireless device for facilitating a transition of the wireless device between an active state and an inactive state or idle mode includes storing an identifier of an idle mode synchronization signal of a source node serving the wireless device responsive to entering an active state from an inactive state or idle mode, reentering the inactive state or idle mode and monitoring the idle mode synchronization signal of the source node while in the inactive state or idle mode.