NR-U Wideband Channel Access via Subband Segmentation
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Solution Overview
Problem
Current NR-U systems face challenges in efficiently operating wideband downlink transmissions in unlicensed spectrum due to limitations in listen-before-talk (LBT) mechanisms, which affect channel access and coexistence with incumbent systems, leading to potential interference and reduced reliability in NR-U operations.
Innovation Solution
The implementation of advanced wideband configuration options for NR-U, including multiple LBT subbands and explicit indication of available LBT bandwidths through DCI format 2_0, allows for more accurate and efficient LBT operations, enabling seamless channel access and minimizing interference by configuring multiple BWPs and adjusting PDSCH transmissions based on successful CCA outcomes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If listen-before-talk (LBT) mechanisms are used for channel access in unlicensed spectrum, then coexistence with incumbent systems is improved, but channel access reliability and transmission efficiency deteriorate due to channel access failures and delays
Solution Approach 1:
The patent segments the unlicensed channel access process into multiple subbands, allowing independent LBT operations on each subband. This segmentation enables the system to access available channels more reliably while maintaining fair coexistence, as failures on one subband do not prevent access on other subbands.
Solution Approach 2:
The patent implements dynamic adjustment of LBT parameters and channel access strategies based on real-time channel conditions. The gNB can adaptively modify LBT configurations for different UEs and subbands, optimizing both reliability and coexistence performance according to varying spectral environments.
2Productivity
If wideband downlink transmissions are implemented in NR-U, then data throughput is improved, but interference management and channel access complexity increase
Solution Approach 1:
The patent divides wideband transmissions into multiple LBT subbands, each subject to independent channel access procedures. This allows the system to maintain wideband throughput potential while managing complexity through modular, independent subband operations rather than treating the entire bandwidth as a single channel.
Solution Approach 2:
The patent enables transmissions on only the necessary subset of subbands where channel access is successful, rather than requiring access to the entire wideband spectrum. This partial action approach maintains throughput efficiency by utilizing available channels while reducing the complexity burden of managing the full bandwidth.
3Productivity
If multiple LBT subbands are configured for channel access, then channel access efficiency is improved, but signaling overhead and configuration complexity increase
Solution Approach 1:
The patent combines multiple LBT subband configurations into a unified framework managed by the gNB, which coordinates channel access across all subbands. This merging approach improves overall channel access efficiency while consolidating signaling overhead at the gNB side, reducing the burden on individual UEs.
Solution Approach 2:
The patent creates a universal LBT configuration framework that can accommodate multiple subbands with different parameters. This multi-functional approach allows efficient channel access across diverse spectral conditions while using a standardized configuration mechanism that reduces overall signaling requirements.
Data Source
AI summary
Systems and methods for downlink transmission using a wideband unlicensed band carrier in 5G networks are described. The gNB determines, based on LBT, which LBT subchannel(s) in a BWP are available during a COT. The gNB transmits an indication of the available subchannels in DCI format 2_0 of a GC-PDCCH of one of the available subchannels and subsequently transmits a PDSCH using the available subchannel(s). The gNB may configure multiple opportunities during the COT and transmit the GC-PDCCH after the initial opportunity. The PDSCH is transmitted on all available subchannels during the COT and, during an initial portion of the COT, may transmit the PDSCH by puncturing symbols of the unavailable subchannels. The indication may include a bitmap of available subchannels or if the LBT outcome is not available, may indicate all or none of the subchannels or available or that the outcome is not available.