LTE-U Channel Reservation Window for Unlicensed Band Efficiency
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Solution Overview
Problem
Existing LTE systems face challenges in efficiently utilizing unlicensed frequency bands due to regulatory requirements for Clear Channel Assessment (CCA), which do not provide detailed solutions for integrating with the current LTE radio frame structure, leading to system overhead and compatibility issues.
Innovation Solution
A channel reservation window arrangement is introduced to support LBT procedures, dividing each window into transmission and idle parts, with the length of the transmission part maximized to meet a predetermined criterion, ensuring efficient data transmission and reliable CCA processes, while maintaining compatibility with LTE frame structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Clear Channel Assessment (CCA) procedures are implemented for unlicensed band communication, then regulatory compliance is achieved, but system overhead increases and compatibility with LTE frame structure becomes problematic
Solution Approach 1:
The patent segments the channel reservation window into distinct parts: a first part for potential data transmission and a second part for CCA procedures. This segmentation allows the system to perform CCA assessments without disrupting the overall LTE frame structure, thereby maintaining regulatory compliance while minimizing system overhead and preserving compatibility with existing LTE frameworks.
2Productivity
If CCA procedures are integrated into LTE frame structure, then unlicensed band utilization is enabled, but detailed integration solutions are lacking leading to overhead and compatibility issues
Solution Approach 1:
The patent performs CCA procedures in advance during the second part of the channel reservation window before actual data transmission in the first part. This preliminary action ensures that the channel is clear for transmission while maintaining a clear separation between assessment and transmission activities, enabling efficient unlicensed band utilization without creating integration complexity with LTE frame structure.
3Productivity
If transmission part length is maximized in channel reservation window, then data transmission efficiency is improved, but CCA reliability may be compromised
Solution Approach 1:
The patent dynamically adjusts the length of the second part (CCA part) of the channel reservation window based on the channel occupancy time determined during CCA procedures. By changing this parameter adaptively, the system ensures sufficient time for reliable CCA assessments while maximizing the first part for data transmission, thereby achieving both transmission efficiency and CCA reliability without compromise.
Data Source
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AI summary
The invention relates to a solution comprising: receiving, at a user equipment (800), configuration of a channel reservation window (300) format; determining a position of a transmission part (304) of at least one channel reservation window (300) using the configured channel reservation window format, wherein the at least one channel reservation window is divided into the transmission part (304) and an idle part (306) comprising one or more symbols in one sub-frame. The length of the transmission part (304) is maximized, at a symbol level accuracy, such that a ratio between the length of the idle part (306) and the length of the transmission part (304) fulfils a predetermined criterion. Based on the at least one channel reservation window, a data transmission is received.