Coherence Indication for DMRS Bundling in PUSCH
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Solution Overview
Problem
In wireless communication systems, especially in LTE and NR technologies, the base station faces challenges in determining whether physical uplink shared channel (PUSCH) transmissions are phase coherent, leading to communication errors and inaccurate channel estimation due to unclear conditions for demodulation reference signal (DMRS) bundling.
Innovation Solution
A method where user equipment (UE) receives a configuration to apply DMRS bundling and transmits a coherence indication with uplink control information (UCI) to indicate phase coherence across multiple PUSCH transmissions, enabling joint channel estimation by the base station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the base station signals to the UE to apply DMRS bundling to PUSCH transmissions, then channel estimation accuracy is improved, but the base station cannot unambiguously determine whether the conditions for DMRS bundling are satisfied, leading to communication errors
Solution Approach 1:
The patent introduces a feedback mechanism where the UE transmits a coherence indication to the base station. This feedback provides the base station with unambiguous information about whether phase coherence conditions are satisfied, resolving the uncertainty that caused communication errors while maintaining the channel estimation accuracy benefits of DMRS bundling.
Solution Approach 2:
The coherence indication acts as an intermediary information element that bridges the knowledge gap between UE and base station. It carries the phase coherence status from the UE to the base station, enabling the base station to make informed decisions about DMRS bundling application without directly observing the UE's internal phase coherence state.
2Productivity
If the base station applies DMRS bundling to PUSCH transmissions, then spectral efficiency is improved through joint channel estimation, but communication errors occur due to ambiguous determination of bundling conditions
Solution Approach 1:
The coherence indication feedback mechanism enables the base station to reliably determine when to apply DMRS bundling. By receiving unambiguous information from the UE about phase coherence conditions, the base station can confidently apply bundling to improve spectral efficiency without risking communication errors from incorrect bundling decisions.
3Reliability
If the UE transmits coherence indication in UCI multiplexed with PUSCH, then unambiguous phase coherence indication is provided, but uplink control overhead is increased
Solution Approach 1:
The coherence indication is merged with existing UCI and multiplexed with the PUSCH transmission. This combining approach allows the coherence information to be transmitted efficiently alongside other control information, minimizing the incremental overhead while ensuring reliable delivery of the phase coherence status.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive a configuration that indicates to the UE to apply demodulation reference signal (DMRS) bundling to physical uplink shared channel (PUSCH) transmissions. The UE may maintain phase coherence across multiple PUSCH transmissions, to which the DMRS bundling is applied, to enable joint channel estimation across the multiple PUSCH transmissions. The UE may transmit, based at least in part on the configuration, uplink control information (UCI) that includes a coherence indication. The UE may multiplex the UCI with a PUSCH transmission of the multiple PUSCH transmissions to which the DMRS bundling is applied. The coherence indication may indicate whether the PUSCH transmission is coherent with one or more other PUSCH transmissions, of the multiple PUSCH transmissions, transmitted by the UE. Numerous other aspects are described.