Ephemeral Identifier Management for Wireless User Equipment

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Solution Overview

Problem

In wireless communication systems, maintaining user equipment (UE) context at an anchor node while allowing downlink messages to be addressed to UE in an inactive mode poses challenges, particularly in reducing latency and overhead associated with context fetches and security key updates, especially in scenarios involving grant-free transmissions and mobility.

Innovation Solution

The system employs ephemeral identifiers like eC-RNTI, which are assigned to UE after uplink data transmission, allowing downlink messages to be addressed without fetching the UE context from the anchor node, and transitioning to persistent identifiers for secure communication, thereby reducing latency and overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If UE context is maintained at anchor node in inactive mode, then network resource usage is reduced, but downlink message delivery latency increases due to context fetch requirements

Engineering Contradiction:

Improvenetwork resource usageVSAvoiddownlink message delivery latency

Core Design Contradiction:

Loss of energyVSLoss of time

Solution Approach 1:

The system performs preliminary actions by assigning ephemeral identifiers (eC-RNTI) to UEs in inactive mode before downlink messages need to be delivered. These ephemeral identifiers are prepared in advance and can be used immediately for addressing downlink messages without requiring context fetches, thus reducing latency while maintaining the UE in inactive mode

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Ephemeral identifiers serve as intermediaries between the anchor node (where UE context is maintained) and the serving node (where downlink messages are delivered). The eC-RNTI allows the serving node to address downlink messages to UEs without needing to fetch the full UE context from the anchor node, thus mediating the communication efficiently

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of time

If ephemeral identifiers are used for downlink addressing, then context fetch overhead is reduced, but identifier management complexity increases

Engineering Contradiction:

Improvecontext fetch overheadVSAvoididentifier management complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The system changes the identifier parameter from persistent identifiers (which require full context management) to ephemeral identifiers (eC-RNTI) for downlink addressing in inactive mode. This parameter change simplifies the management overhead while maintaining the ability to deliver downlink messages efficiently. The ephemeral identifiers have simpler structures and management requirements compared to full UE contexts

Inventive Principle:

Principle #35Parameter changes

3Reliability

If UE transitions to connected mode for downlink reception, then message delivery reliability is improved, but energy consumption increases

Engineering Contradiction:

Improvemessage delivery reliabilityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Instead of fully transitioning the UE to connected mode (excessive action), the system uses a partial approach by maintaining the UE in inactive mode and using ephemeral identifiers for downlink addressing. This partial action achieves sufficient message delivery reliability for inactive mode UEs without the full energy cost of connected mode transition, representing an optimized intermediate solution

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11546752B2System and method for user equipment identification and communications

Publication Date: 2023.01.03 FUTUREWEI TECHNOLOGIES INC

AI summary

A method for identifier management for user devices operating in an inactive mode includes receiving a first uplink transmission including a user device identifier associated with a user device, transmitting a first downlink transmission including an indication of an ephemeral identifier assigned to the user device, transmitting a second downlink transmission including data associated with the ephemeral identifier, and discarding the ephemeral identifier.