Coupled Downlink-Uplink Reference Signals for Indoor Multi-RTT Positioning

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Solution Overview

Problem

Existing multi-RTT positioning methods in 5G networks are inefficient in terms of resource usage and accuracy, particularly in indoor scenarios where a Line-of-Sight path is not available, leading to biased position estimation and increased power consumption.

Innovation Solution

Implementing a coupling relationship between downlink and uplink reference signals to adjust transmission modes based on channel conditions, allowing for the cancellation or optimization of uplink reference signal transmission when a Line-of-Sight path is absent, thereby minimizing power consumption and interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If uplink reference signal transmission is performed in all conditions, then positioning measurement coverage is maximized, but power consumption and interference increase significantly

Engineering Contradiction:

Improvepositioning measurement coverageVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the uplink reference signal transmission adaptive rather than static. The gNB dynamically adjusts whether to transmit the uplink reference signal based on real-time channel condition measurements (downlink reference signal received power). This resolves the contradiction by enabling transmission only when necessary for accurate positioning, thereby reducing unnecessary power consumption while maintaining measurement coverage where needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the transmission parameter (uplink reference signal) based on channel condition parameters (downlink reference signal received power). When the downlink received power exceeds a threshold, indicating good channel conditions, the uplink reference signal transmission is cancelled. This parameter-based adaptation resolves the contradiction by aligning transmission behavior with actual channel quality, reducing power consumption without compromising positioning accuracy when channels are favorable.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If uplink reference signal transmission is performed in all conditions, then positioning accuracy is maintained, but harmful interference increases

Engineering Contradiction:

Improvepositioning accuracyVSAvoidinterference

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The system dynamically adapts uplink reference signal transmission based on measured channel conditions. The gNB measures downlink reference signal received power and uses this information to determine whether uplink transmission should occur. This dynamic approach reduces interference by avoiding unnecessary transmissions in good channel conditions while maintaining positioning accuracy when measurements are actually needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent converts the potentially harmful effect of continuous transmission into a beneficial adaptive system. By using the downlink received power measurement (which would otherwise be just a channel indicator) as the control signal for uplink transmission, the system turns what could be wasted energy into a useful control mechanism that reduces overall interference while maintaining positioning performance.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Use of energy by moving object

If downlink reference signal transmission is cancelled when uplink channel conditions are poor, then power consumption is reduced, but positioning reliability decreases

Engineering Contradiction:

Improvepower consumptionVSAvoidpositioning reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system implements feedback by measuring the downlink reference signal received power and using this feedback to control uplink reference signal transmission. The gNB continuously monitors channel conditions and adjusts transmission behavior accordingly. This feedback mechanism resolves the contradiction by ensuring that transmissions are cancelled only when channel conditions truly indicate they are unnecessary, thereby reducing power consumption while maintaining positioning reliability through informed decision-making.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12407468B2Coupled downlink and uplink reference signals for efficient multi-RTT positioning

Publication Date: 2025.09.02 NOKIA TECHNOLOGIES OY

AI summary

According to an aspect, there is provided a terminal device for performing the following. The terminal device maintains, in a memory, configurations of downlink and uplink reference signals. In response to receiving a configuration of a coupling relationship between the downlink and uplink reference signals from an access node, the terminal device stores it to the memory. The terminal device measures, in response to receiving the downlink reference signal from the access node, the downlink reference signal. The terminal device determines whether a radio channel between the terminal device and the access node meets one or more pre-defined criteria. If the one or more pre-defined criteria are not met, the terminal device determines an adjusted transmission mode for the uplink reference signal. If the adjusted transmission mode determines one or more transmission parameters, the terminal device transmits the uplink reference signal to the access node using the adjusted transmission mode.