Disaster PLMN Signaling With Bitmap Mapping for Lower Radio Overhead

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Solution Overview

Problem

The challenge of signaling disaster PLMNs in wireless communication networks results in significant signaling overhead due to the need to indicate multiple PLMNs, which wastes radio resources and is inefficient.

Innovation Solution

Implementing a flexible signaling approach that includes a common list of disaster PLMNs applicable to all serving PLMNs, PLMN-specific lists, and a mapping mechanism using bitmaps to efficiently associate disaster PLMNs with serving PLMNs, reducing the need for repeated signaling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple PLMN identities are broadcast in SIB1 to support disaster roaming, then disaster roaming capability is enabled, but signaling overhead increases and radio resources are wasted

Engineering Contradiction:

Improvedisaster roaming capabilityVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent segments the PLMN identity information into two parts: a common list of disaster PLMN identities applicable to all serving PLMNs, and PLMN-specific lists for individual serving PLMNs. This segmentation allows the common information to be broadcast once while enabling selective association with specific serving PLMNs through bitmap indicators, thereby reducing redundant signaling overhead while maintaining complete disaster roaming capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary action by pre-defining a common list of disaster PLMN identities that can be associated with multiple serving PLMNs. By establishing this common list in advance and using bitmap indicators to associate it with relevant serving PLMNs, the system avoids the need to repeatedly broadcast complete PLMN identity information for each serving PLMN, thus reducing signaling overhead before the actual disaster roaming operation occurs.

Inventive Principle:

Principle #10Preliminary action

2Loss of energy

If a common list of disaster PLMNs is provided for multiple serving PLMNs, then signaling overhead is reduced, but the ability to provide PLMN-specific disaster PLMN information is limited

Engineering Contradiction:

Improvesignaling overheadVSAvoidPLMN-specific customization

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent divides the disaster PLMN information structure into a common list portion and PLMN-specific list portions. The common list contains disaster PLMN identities that apply to multiple serving PLMNs, while separate PLMN-specific lists allow for customization when needed. Bitmap indicators enable flexible association between serving PLMNs and the common list, providing adaptability while minimizing redundant signaling.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The common list of disaster PLMN identities serves multiple serving PLMNs simultaneously, providing a universal solution that reduces signaling overhead. The list is designed to be multi-functional, capable of being associated with any combination of serving PLMNs through bitmap indicators, thus achieving both efficiency and versatility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If bitmap indicators are used to associate disaster PLMNs with serving PLMNs, then signaling efficiency is improved, but system complexity increases

Engineering Contradiction:

Improvesignaling efficiencyVSAvoidsystem complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent introduces bitmap indicators as an intermediary mechanism that efficiently associates the common disaster PLMN list with specific serving PLMNs. The bitmaps serve as a compact mapping structure where each bit corresponds to a serving PLMN, enabling the system to indicate associations with minimal signaling overhead while maintaining a systematic and manageable complexity level.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP4381812B1Signalling approaches for disaster plmns

Publication Date: 2025.09.03 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

A method of operating a network node includes transmitting (202) system information in a cell served by the network node. The system information includes a set of one or more disaster PLMNs. A UE that can normally connect to one of the disaster PLMNs in the set of disaster PLMNs can use the cell in the event of a disaster in which the UE is unable to communicate with the disaster PLMN. A method of operating a UE includes receiving (302) system information in a cell of the RAN, wherein the system information includes a set of one or more disaster PLMNs, including a disaster PLMN to which the UE is associated, that can use the cell in the event of a disaster in which the UE is unable to communicate with the disaster PLMN, and communicating (304) with the cell in the event of a disaster in which the UE is unable to communicate with the disaster PLMN.