User Terminal UL Transmission Control in Unlicensed Bands
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Solution Overview
Problem
In LTE systems, adequate uplink transmission in unlicensed bands is threatened by the application of existing UL transmission methods that do not account for interference control through listening, leading to potential disabling of UL transmission and reduced spectral efficiency.
Innovation Solution
Implementing listening-based interference control mechanisms, such as LBT, to determine UL transmission timings and adjust transmission power, allowing user terminals to control UL transmission flexibly based on listening results, even when starting from the middle of a subframe, by configuring a second period after a UL transmission command and using a floating TTI structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing UL transmission methods are applied in unlicensed bands, then UL transmission can be performed according to traditional LTE protocols, but UL transmission may be disabled and spectral efficiency is reduced due to interference from listening results
Solution Approach 1:
The patent applies dynamics by making the UL transmission timing flexible rather than fixed. The user terminal determines the UL transmission timing dynamically based on the listening result, allowing the transmission to occur in a floating TTI (Transmission Time Interval) that adapts to channel conditions. This resolves the contradiction by enabling UL transmission to be both reliable (when channel is clear) and efficient (by capturing available channel opportunities).
Solution Approach 2:
The patent changes the timing parameter from a fixed value to a variable that depends on listening results. Specifically, the UL transmission timing is determined as a floating value within a range based on when the listening function detects the channel is clear, rather than following the fixed timing of existing LTE protocols. This parameter change allows the system to adapt to unlicensed band conditions while maintaining reliable transmission.
2Object-affected harmful factors
If listening-based interference control is implemented, then interference in unlicensed bands is reduced, but UL transmission timing control becomes more complex
Solution Approach 1:
The patent applies self-service by having the user terminal autonomously determine its UL transmission timing based on its own listening results, without requiring complex centralized scheduling or coordination with the base station for each transmission opportunity. The terminal independently performs listening, determines when the channel is clear, and schedules its own transmission within the configured range, simplifying the overall system complexity while effectively controlling interference.
3Productivity
If UL transmission timing is made flexible based on listening results, then spectral efficiency is maintained, but transmission timing determination becomes more difficult
Solution Approach 1:
The patent applies preliminary action by having the base station pre-configure the range of possible UL transmission timings before the user terminal performs listening. The terminal uses this pre-configured range to quickly determine its transmission timing based on when listening detects the channel is clear, rather than having to calculate or negotiate timing dynamically. This preliminary configuration simplifies the timing determination process while maintaining spectral efficiency.
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
The present invention is designed to adequately control UL transmission in cells (for example, unlicensed bands) where listening is executed prior to transmission cell. The present invention provides a transmission section that transmits a UL signal, and a control section that controls the transmission of the UL signal based on a UL transmission command that is reported from a radio base station and based on listening that is executed before the UL signal is transmitted, and, when support is provided to transmit a DL signal and/or a UL signal from the middle of a subframe based on the result of listening, the control section transmits the UL signal in a second period, which is configured a first period after the UL transmission command is received.