DM-RS Beam Association for 5G NR Mobile Terminal Processing Load Reduction

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Solution Overview

Problem

Current downlink control channel reception mechanisms in 5G NR systems incur a significant processing load at mobile terminals, especially in unlicensed spectrum operations, due to blind decoding attempts, which are not efficiently related to successful receptions and are worsened by timing constraints from Listen-Before-Talk procedures.

Innovation Solution

The proposed solution involves associating demodulation reference signal sequences with specific transmission beams, allowing mobile terminals to restrict processing to only relevant signals, thereby reducing the processing load by enabling the terminal to skip unnecessary monitoring based on channel estimation quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mobile terminal performs blind decoding attempts for all downlink control channel candidates, then all possible control channels can be detected, but processing load increases significantly

Engineering Contradiction:

Improvecontrol channel detection reliabilityVSAvoidprocessing load

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the downlink control channel reception process into two stages: first performing channel estimation on DM-RS to obtain quality metrics, then using these metrics to selectively decode only promising PDCCH candidates. This segmentation transforms the traditional approach of uniformly processing all candidates into a hierarchical structure where estimation results guide subsequent decoding decisions, thereby reducing overall processing load while maintaining detection reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of performing full decoding operations on all PDCCH candidates, the patent applies partial action by first performing lighter channel estimation operations on DM-RS for all candidates, then using these estimation results to identify and fully decode only the most promising subset of candidates. This partial processing approach reduces computational complexity while ensuring that the most likely control channels are still detected.

Inventive Principle:

Principle #16Partial or excessive action

2Reliability

If mobile terminal monitors all downlink control channel candidates in unlicensed spectrum, then no control information is missed, but processing load increases due to timing constraints from Listen-Before-Talk procedures

Engineering Contradiction:

Improvecontrol information reception reliabilityVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing channel estimation on DM-RS before attempting full decoding of PDCCH candidates. This preliminary estimation provides quality metrics that guide subsequent decoding decisions, allowing the mobile terminal to skip decoding operations on candidates with poor estimation results. This preliminary filtering action reduces processing time while ensuring that candidates with good estimation quality are still thoroughly processed.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If mobile terminal performs channel estimation on all demodulation reference signals, then accurate channel information is obtained for all candidates, but processing load increases

Engineering Contradiction:

Improvechannel estimation accuracyVSAvoidprocessing load

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses DM-RS channel estimation results as an intermediary to mediate between receiving all PDCCH candidates and fully decoding all candidates. The channel estimation acts as a filtering mechanism that provides quality metrics, allowing the system to selectively proceed with full decoding only for candidates that meet certain quality thresholds. This intermediary step enables the system to maintain measurement precision for all candidates while reducing processing load by avoiding full decoding of poor-quality candidates.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20230047649A1Mobile terminal and base station involved in downlink channel operations including radio channel estimation based on demodulation reference signal

Publication Date: 2023.02.16 PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA

AI summary

The present disclosure relates to a mobile terminal, a base station and respective operation methods. The mobile terminal comprises circuitry, which in operation assumes that a base station is configured to use one of a plurality of transmission beams, receives a downlink control channel candidate and a corresponding demodulation reference signal using one of a plurality of reception beams corresponding to the assumed one of the plurality of transmission beams, performs channel estimation based on the received demodulation reference signal, and, depending on the quality, demodulates the downlink control channel candidate using the channel estimation. The channel estimation is performed using a demodulation reference signal sequence which is generated observing an association which is associating the generated sequence with the assumed one of the plurality of transmission beams such that at least two of the plurality of transmission beams are associated with different demodulation reference signal sequences.