Phase Tracking Reference Signal Configuration for High Doppler Shifts

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Solution Overview

Problem

Current wireless communication systems, particularly in 5G and NR technologies, face challenges in initial access due to high Doppler shifts caused by relative speed between base stations and user equipment, leading to phase noise and difficulties in channel estimation, which affect demodulation performance and network reliability.

Innovation Solution

Implementing a high Doppler configuration that activates a phase tracking reference signal (PTRS) for remaining minimum system information (RMSI) communications, allowing base stations to transmit PTRSs configured by the high Doppler configuration, and indicating its activation to user equipment, enabling effective phase noise compensation and channel estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high Doppler configuration is activated to compensate for phase noise, then demodulation performance is improved, but device complexity increases due to additional PTRS configuration and processing

Engineering Contradiction:

Improvedemodulation performanceVSAvoidPTRS configuration complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the PTRS configuration based on Doppler shift conditions. The base station determines whether to activate PTRS for RMSI communications by evaluating Doppler shift thresholds, and if activated, configures PTRS parameters (such as time density and frequency density) according to the high Doppler configuration. This allows the system to adapt PTRS settings to match actual channel conditions, improving demodulation performance only when needed while avoiding unnecessary complexity in stable conditions.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If PTRS is transmitted for RMSI communications to enable phase tracking, then channel estimation accuracy is improved, but transmission time increases due to additional reference signal overhead

Engineering Contradiction:

Improvechannel estimation accuracyVSAvoidinitial access latency

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies partial action by selectively transmitting PTRS only for RMSI communications when high Doppler configuration is activated, rather than continuously transmitting PTRS for all communications. The base station evaluates whether to activate PTRS based on Doppler shift conditions, and if activated, configures PTRS with specific time density and frequency density parameters. This partial application of PTRS to only the necessary RMSI transmissions reduces overall overhead and latency while maintaining accurate channel estimation when Doppler effects are present.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If high Doppler configuration is used to mitigate Doppler shift effects, then initial access reliability is improved, but system overhead increases due to configuration indication and PTRS signaling

Engineering Contradiction:

Improveinitial access reliabilityVSAvoidconfiguration overhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by using configurable thresholds and density parameters to control PTRS transmission. The base station determines activation based on Doppler shift thresholds and configures PTRS time density and frequency density according to the high Doppler configuration parameters. This parameter-based control allows the system to adapt the quantity of PTRS transmissions to match actual channel conditions, improving initial access reliability when needed while minimizing configuration overhead in stable conditions.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution improves demodulation performance, reduces latency, and enhances network reliability by mitigating the effects of high Doppler shifts, thereby improving initial access procedures in wireless communication systems.

Implementation Method 1

high Doppler shifts caused by relative speed between base stations and user equipment

Methodology Applied

Scientific EffectDoppler effect: Doppler Effect

Implementation Method 2

phase noise and difficulties in channel estimation

Methodology Applied

Scientific EffectPhase noise:

Data Source

PatentUS11695595B2Phase tracking for initial access

Publication Date: 2023.07.04 QUALCOMM INC

AI summary

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive an indication that a high Doppler configuration is activated. The UE may detect, based at least in part on receiving the indication that the high Doppler configuration is activated, a phase tracking reference signal (PTRS) for a remaining minimum system information (RMSI) communication. The PTRS may be configured by the high Doppler configuration. Numerous other aspects are provided.