Dynamic Reference Signal Scheduling for 5G NR-U LBT Failures
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Solution Overview
Problem
In 5G NR-U communication, the failure of Listen-before-talk (LBT) mechanism to transmit Discovery Reference Signals (DRS) in the DMTC window leads to Radio Link Failure (RLF) and poor wireless measurement efficiency due to inability to perform Radio Link Monitoring (RLM) and Radio Resource Management (RRM).
Innovation Solution
A method where user equipment (UE) monitors and receives dynamic scheduling information for reference symbols from a base station, allowing timely reception and transmission of reference symbols, even outside the DMTC window, to avoid LBT failures and enhance measurement opportunities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LBT mechanism is used to ensure fairness in unlicensed band, then channel access fairness is improved, but transmission reliability deteriorates when channel is occupied
Solution Approach 1:
The patent applies dynamics by transitioning from static periodic transmission schedules to dynamic on-demand transmission. The base station receives indication information from UE and dynamically adjusts reference signal transmission timing, allowing flexible scheduling that adapts to channel availability while ensuring fairness through LBT mechanism.
Solution Approach 2:
The patent implements feedback through the indication information mechanism where UE feeds back its measurement needs to the base station. This feedback loop enables the base station to adjust transmission timing dynamically, ensuring reliable reference signal delivery while maintaining channel access fairness.
2Productivity
If reference signal is transmitted periodically in DMTC window, then measurement efficiency is improved, but flexibility deteriorates when LBT fails
Solution Approach 1:
The patent transforms the static periodic transmission pattern into a dynamic on-demand system. Instead of fixed DMTC window transmission, the base station now transmits reference signals dynamically based on real-time channel conditions and UE indication information, achieving both efficiency and flexibility.
Solution Approach 2:
The patent changes the transmission parameter from fixed periodic timing to variable on-demand timing. The transmission moment is adjusted based on channel availability and measurement needs, allowing the system to adapt to LBT failures while maintaining measurement efficiency.
3Reliability
If UE monitors dynamic scheduling information, then transmission reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by having the existing PDCCH monitoring mechanism serve dual purposes: both data channel scheduling and reference signal scheduling. This multi-functionality approach avoids adding separate monitoring mechanisms, thereby improving reliability without significantly increasing device complexity.
Data Source
AI summary
A reference signal transmission method and apparatus are provided. The method includes that a user equipment (UE) monitors dynamic scheduling information sent by a base station, where the dynamic scheduling information includes scheduling information of a reference symbol. Further, the UE determines, according to the dynamic scheduling information, the scheduling information of the reference symbol and receives, according to the scheduling information of the reference symbol, the reference symbol.