Multi-Channel LBT for Wideband NR in Unlicensed Spectrum
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently utilizing unlicensed spectrum due to the need for wideband channel availability assessment, where a single node's LBT failure prevents transmission despite available channels within the wideband channel.
Innovation Solution
Implementing multi-channel listen before talk (LBT) procedures with selective adjustment of contention windows and bandwidth based on channel-specific measurements and WLAN preamble detection to optimize channel usage in unlicensed spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single LBT procedure is performed on a wideband channel, then channel availability assessment is simplified, but transmission opportunities are lost when individual channels within the wideband channel are available
Solution Approach 1:
The wideband channel is segmented into multiple individual channels, each subjected to separate LBT procedures. This allows the system to identify and transmit on available channels while avoiding occupied ones, thereby improving channel utilization without requiring a single complex wideband assessment procedure.
Solution Approach 2:
The system dynamically adjusts LBT parameters including contention window sizes and bandwidth configurations based on channel-specific conditions. This dynamic adaptation enables optimized transmission strategies for each channel state, balancing complexity and productivity by applying different LBT rigor levels to different channels.
2Reliability
If contention window size is increased to reduce collisions, then LBT success rate improves, but transmission delay increases
Solution Approach 1:
Different contention window sizes are assigned to different channels based on their specific conditions such as interference levels and occupancy patterns. This local optimization allows channels with high collision rates to use larger contention windows while channels with better conditions use smaller windows, maintaining overall reliability without excessive delay.
Solution Approach 2:
The system dynamically changes LBT parameters including contention window size and bandwidth based on measured channel conditions. When channel conditions improve, parameters are adjusted to reduce delay; when conditions deteriorate, parameters are adjusted to maintain success rate, creating a responsive balance between reliability and time loss.
Data Source
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AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a wireless communication device may perform rate matching of coded bits of each transport block, of a plurality of transport blocks, on a per-channel basis among a plurality of channels in a wideband channel of an unlicensed spectrum. The rate matching is performed on the per-channel basis in a first set of slots and such that coded bits of each transport block are mapped to a respective one of the plurality of channels. The wireless communication device may receive, after a transmission of the plurality of transport blocks on the plurality of channels, per-channel acknowledgment information. The wireless communication device may selectively adjust a plurality of contention windows, each associated with a listen before talk procedure to be performed on a respective one of the plurality of channels. Numerous other aspects are provided.