Fractional Subframe Symbol Reporting for LBT
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Solution Overview
Problem
In LTE radio communication systems operating in unlicensed bands, the timings of data transmission start and end based on LBT results may not align with subframe boundaries, leading to challenges in resource allocation and increased risk of demodulation errors in user terminals.
Innovation Solution
Implementing a method to report the number of symbols used in a fractional subframe to user terminals via L1 signaling, allowing for data transmission to be adjusted to prevent demodulation errors and maximize spectral efficiency, even when using the maximum possible burst length after LBT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data transmission uses maximum burst length after LBT in unlicensed bands, then spectral efficiency is improved, but demodulation errors occur in user terminals due to timing misalignment with subframe boundaries
Solution Approach 1:
The patent segments the transmission timing information by separately indicating the start symbol position and length of data transmission within a subframe. This allows the system to handle fractional subframe transmissions (where data doesn't align with subframe boundaries) by providing precise granularity control, thus maintaining demodulation accuracy while enabling flexible burst lengths for high spectral efficiency.
2Productivity
If data transmission timing is flexible to maximize burst length, then resource utilization is improved, but resource allocation complexity increases due to non-subframe-aligned timing
Solution Approach 1:
The patent changes the parameter representation from traditional subframe-based timing to symbol-level timing indicators. By using start symbol position and transmission length parameters, the system can dynamically adjust transmission timing to match LBT results and burst length requirements, maximizing resource utilization while keeping allocation logic manageable through standardized parameter signaling.
3Device complexity
If traditional subframe-based resource allocation is used, then system simplicity is maintained, but spectral efficiency decreases due to inability to utilize partial subframes
Solution Approach 1:
The patent introduces dynamic timing adjustment capabilities that allow the system to adapt transmission parameters based on LBT outcomes and channel conditions. The start symbol position and transmission length can be dynamically changed to match actual available resources, enabling the system to utilize partial subframes and improve spectral efficiency while maintaining relatively simple operation through standardized signaling mechanisms.
Data Source
Figure 1A~1B
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AI summary
The present invention is designed to set forth a method that can prevent demodulation errors in user terminals and make maximum use of resources when data transmission is carried out by using only part of the OFDM symbols in subframes. A user terminal according to an example of the present invention has a receiving section that receives information about the number of symbols used in a given subframe of a carrier where LBT (Listen Before Talk) is configured, in the carrier, and a control section that controls a receiving process in the given subframe based on the information about the number of symbols used.