User Terminal Channel Access with Random Back-off for Uplink
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Solution Overview
Problem
In the context of next-generation mobile communication systems, particularly in unlicensed bands, there is a need for efficient and fair coexistence with other systems and operators, especially regarding uplink (UL) communication standards for user terminals.
Innovation Solution
The proposed solution involves a user terminal equipped with a reception section to receive downlink (DL) signals containing UL transmission indications and a control section that manages UL data transmission based on these indications and a channel access procedure with random back-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If listening (LBT) is applied before UL signal transmission in user terminal, then fair coexistence with other systems and operators is improved, but UL transmission may be delayed or prevented for long periods
Solution Approach 1:
The patent applies dynamic adjustment of listening parameters based on channel conditions and transmission priorities. The user terminal dynamically modifies back-off counter values and listening durations according to the importance of UL data (e.g., HARQ-ACK signals receive different treatment than regular data), allowing critical communications to proceed with reduced delay while maintaining fairness for normal traffic.
Solution Approach 2:
The invention changes key parameters of the listening procedure including back-off counter initialization values, listening window durations, and threshold levels based on channel occupancy conditions and signal priority. By adjusting these parameters dynamically, the system balances between ensuring fair spectrum access and preventing excessive delays for time-sensitive uplink transmissions.
2Object-affected harmful factors
If listening is applied before UL transmission, then interference control and coexistence with Wi-Fi/other systems is improved, but communication reliability may deteriorate
Solution Approach 1:
The patent implements feedback mechanisms where the user terminal monitors the outcomes of listening procedures and adjusts subsequent listening behavior accordingly. When listening causes unnecessary transmission delays or failures, the terminal feeds back this information to modify future listening intensity, creating a self-adjusting system that maintains interference control while preserving communication reliability through learned optimization.
Solution Approach 2:
The invention performs preliminary assessments of channel conditions and transmission priorities before initiating full listening procedures. By pre-evaluating the urgency and importance of UL data, the system can prepare appropriate listening strategies in advance, reducing the impact of listening on communication reliability while maintaining effective interference control.
3Reliability
If random back-off is used in channel access procedure, then fair coexistence with other systems is improved, but UL transmission timing becomes less predictable
Solution Approach 1:
The patent dynamically adjusts the randomness of back-off behavior based on channel conditions and transmission priorities. For high-priority transmissions, the back-off becomes more deterministic with smaller random variations, while for normal traffic, full random back-off is applied to ensure fairness. This dynamic approach maintains fair coexistence while improving timing predictability when needed.
Data Source
AI summary
To actualize proper UL communication in a communication system using a cell where application of listening is defined, a user terminal has a reception section that receives a DL signal including a UL transmission indication, and a control section that controls transmission of UL data based on the UL transmission indication and a channel access procedure before UL transmission, where the control section controls so as to perform a channel access procedure with random back-off.