UE Positioning in RRC Inactive State for Low-Power Event Reporting

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Solution Overview

Problem

Existing wireless communication systems face challenges in efficiently locating mobile devices in a Radio Resource Control (RRC) Inactive state, leading to increased power consumption and latency due to unnecessary maintenance of RRC connections during extended positioning measurements.

Innovation Solution

A method and apparatus that enable UE positioning in the RRC Inactive state by allowing the UE to enter this state after receiving a location request, send an RRC Resume Request with an event indication, and remain in this state while receiving RRC Release messages, thereby reducing power consumption and latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the UE maintains an RRC Connected state during location measurements, then positioning accuracy can be ensured through continuous signal monitoring, but power consumption increases and latency is introduced

Engineering Contradiction:

Improvepositioning accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by enabling the UE to transition between RRC Connected and RRC Inactive states based on positioning requirements. The UE dynamically adjusts its RRC state: remaining connected during active positioning measurements to ensure accuracy, and transitioning to inactive state during intervals when positioning is not required to reduce power consumption. This dynamic state management resolves the contradiction between maintaining positioning accuracy and reducing energy usage.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements periodic action through configured positioning triggers that activate positioning measurements at specific intervals or events rather than continuously. The network configures the UE with positioning triggers (e.g., periodic timers, event-based triggers) that activate the RRC Connected state only when positioning is needed, allowing the UE to return to the lower-power RRC Inactive state between measurements. This periodic activation pattern reduces overall power consumption while maintaining positioning capability when required.

Inventive Principle:

Principle #19Periodic action

2Use of energy by moving object

If the UE transitions to RRC Inactive state for power saving, then energy consumption is reduced, but positioning response time increases

Engineering Contradiction:

Improvepower consumptionVSAvoidpositioning response time

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-configuring the UE with positioning parameters, measurement configurations, and trigger conditions while in the RRC Inactive state. The network provides assistance data, measurement configurations, and positioning protocol parameters in advance during the inactive period. When a positioning trigger occurs, the UE can immediately resume to RRC Connected state and execute pre-prepared measurement procedures, significantly reducing the positioning response time compared to establishing all configurations from scratch.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements self-service by enabling the UE to autonomously manage its RRC state transitions based on configured positioning triggers. The UE monitors for trigger conditions (periodic timers, event thresholds) and autonomously transitions between RRC Inactive and RRC Connected states without requiring network intervention for each state change. This self-managed state transition mechanism reduces signaling overhead and accelerates response time while maintaining power-saving benefits.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If the UE frequently transitions between RRC states for positioning, then positioning flexibility is improved, but signaling overhead and system complexity increase

Engineering Contradiction:

Improvepositioning flexibilityVSAvoidsignaling overhead

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing the RRC state management mechanism to serve multiple functions simultaneously: positioning measurements, power saving, mobility management, and network control. The same RRC state transition framework handles both positioning-related activities and general radio resource management. The positioning triggers and state transitions reuse existing RRC protocol mechanisms rather than introducing separate dedicated signaling pathways, thereby reducing overall system complexity while maintaining positioning flexibility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12392858B2Method and apparatus for location of a user equipment in an inactive state

Publication Date: 2025.08.19 QUALCOMM INC

AI summary

Positioning of a UE is supported in a Radio Resource Control (RRC) Inactive state. The UE receives a request for periodic or triggered location and enters the RRC Inactive state. When an event is detected, the UE sends an RRC Resume Request to a gNB that includes an indication of the event. The indication may be an event report that may include downlink positioning measurements. The gNB forwards the event report to a location server, and may later receive and return an event report acknowledgement to the UE in an RRC Release. The indication may instead trigger uplink positioning, with the base station sending an uplink Sounding Reference Signal (SRS) configuration to the UE in an RRC Release, causing the UE to transmit uplink SRS signals to be measured by gNBs. For uplink related position methods like RTT, the gNB can receive both types of indication.