Downlink Carrier Operation in Unlicensed Spectrum via LBT
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless communication systems face challenges in efficiently operating in unlicensed spectrum bands due to the lack of effective mechanisms for managing downlink transmissions, particularly in managing available bandwidth and channel occupancy times, which can lead to interference and inefficient resource utilization.
Innovation Solution
The implementation of listen-before-talk (LBT) operations in unlicensed spectrum, where user equipment (UE) receives downlink control information including available bandwidth information and channel occupancy time, and processes physical downlink shared channel transmissions accordingly, allowing for dynamic adjustment of transmissions to avoid collisions and optimize resource use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If downlink transmissions are performed in unlicensed spectrum without LBT mechanisms, then transmission continuity is improved, but interference with other unlicensed devices increases and resource utilization efficiency deteriorates
Solution Approach 1:
The patent implements dynamic bandwidth adjustment where the UE adapts its reception bandwidth based on LBT outcomes and available bandwidth indications from the base station. The UE can switch between different bandwidth parts (BWPs) depending on channel availability, making the system flexible and adaptive to changing unlicensed spectrum conditions while maintaining transmission efficiency
Solution Approach 2:
The base station dynamically changes the bandwidth parameter by indicating available bandwidth through DCI messages. The UE adjusts its reception parameters based on these indications, allowing the system to optimize resource utilization by matching transmission parameters to actual channel availability in unlicensed spectrum
2Productivity
If wideband downlink transmissions are performed in unlicensed spectrum, then data throughput is improved, but collision probability with other unlicensed devices increases
Solution Approach 1:
The patent divides the unlicensed spectrum into multiple bandwidth parts (BWPs) that can be independently managed. Instead of attempting wideband transmissions across the entire unlicensed spectrum, the system segments the bandwidth and transmits only in available segments, reducing collision probability while maintaining overall throughput through parallel or sequential transmission across multiple BWPs
Solution Approach 2:
The system performs partial bandwidth transmissions by selecting only the portion of the spectrum that is currently available through LBT. Rather than attempting full wideband transmissions that would likely collide, the system transmits in available sub-bands and combines results, achieving sufficient throughput without the excessive collision risk of full wideband operation
3Reliability
If the UE monitors the entire BWP for PDSCH transmissions, then reception reliability is improved, but processing complexity and energy consumption increase
Solution Approach 1:
The patent applies local quality by having the UE focus its monitoring and processing efforts only on the specific bandwidth portions indicated as available by the base station. Instead of uniformly monitoring the entire BWP, the UE concentrates resources on relevant local segments, reducing processing complexity and energy consumption while maintaining reception reliability in the active bandwidth portions
Data Source
AI summary
Systems, devices, and techniques for listen-before-talk (LBT) operations in unlicensed spectrum are described. A described technique includes receiving, by a user equipment (UE), a downlink control information (DCI) message, the DCI message including available bandwidth information and a channel occupancy time (COT) duration, the available bandwidth information being associated with one or more LBT bandwidths of a bandwidth part (BWP) in unlicensed spectrum; receiving, by the UE, one or more physical downlink shared channel (PDSCH) transmissions in the BWP, during the COT duration; and processing the one or more PDSCH transmissions based on the available bandwidth information.