Carrier Aggregation for LBT Reliability in Unlicensed Spectrum
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Solution Overview
Problem
Current wireless communication technologies, particularly in unlicensed bands, face challenges in ensuring reliability for Ultra-Reliable and Low Latency Communication (URLLC) services due to limitations in Clear Channel Assessment (CCA) or Listen-Before-Talk (LBT) procedures, which fail to provide satisfactory results for services with strict reliability requirements.
Innovation Solution
A method where a wireless device or access node determines a set of carriers requiring LBT procedures and aggregates them to meet a reliability target by redundantly performing wireless transmissions, using the aggregated carriers to increase the likelihood of successful transmission while avoiding excessive carrier usage, with the option to fallback to licensed carriers if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carrier aggregation is used to redundantly perform transmissions on multiple carriers, then transmission reliability is improved, but device complexity increases
Solution Approach 1:
The patent segments the transmission reliability problem by dividing the transmission into multiple independent carriers. Each carrier performs an independent LBT procedure and transmission attempt, so that the failure of one carrier does not necessarily fail the entire transmission. This segmentation allows the system to achieve higher reliability through multiple parallel attempts without requiring a single complex transmission system.
Solution Approach 2:
The patent introduces dynamic control mechanisms where the gNB can dynamically adjust the number of carriers to aggregate based on reliability requirements and channel conditions. The system can adaptively select which carriers to use and how many carriers to aggregate, making the complexity manageable through intelligent control rather than fixed complex architecture.
2Reliability
If multiple carriers are aggregated for redundant transmissions, then transmission reliability is improved, but the number of LBT procedures increases
Solution Approach 1:
The patent applies partial action by aggregating only the necessary number of carriers to meet the reliability target, rather than always using maximum carrier aggregation. The system can determine the minimum number of carriers needed to achieve the required reliability level, avoiding excessive LBT procedures when lower reliability is sufficient, thus improving overall productivity.
3Adaptability or versatility
If unlicensed carriers are used for transmission, then spectrum utilization is improved, but transmission reliability deteriorates
Solution Approach 1:
The patent merges multiple unlicensed carriers into an aggregated set that functions as a unified transmission system. By combining the reliability characteristics of multiple carriers through redundancy, the system achieves reliability levels comparable to licensed carriers while still utilizing the flexibility and additional spectrum of unlicensed bands.
Solution Approach 2:
The patent changes the reliability parameter by transforming single-carrier transmissions into multi-carrier aggregated transmissions. This parameter change allows the system to achieve high reliability in unlicensed bands by adjusting the number of carriers and their aggregation configuration, effectively changing the reliability characteristics of the transmission system.
Data Source
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AI summary
A wireless device (11, 12) determines a set of carriers. The carriers each require a listen- before-talk, LBT, procedure before transmitting on the carrier. Further, the wireless device (11, 12) determines a reliability target for a wireless transmission from the wireless device (11, 12) to the wireless communication network, in particular to an access node (101-1, 101- 2, 101-3, 101-4) of the wireless communication network. Depending on the reliability target, the wireless device (11, 12) controls aggregation of carriers from the set for redundantly 10 performing the wireless transmission on the aggregated carriers.