Unlicensed Band Channel Access with Fixed-Duration Retry Scheduling
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Solution Overview
Problem
The challenge in using unlicensed frequency bands for cellular communication is the difficulty in ensuring communication quality due to potential interference with existing wireless devices and the need for a robust coexistence mechanism to avoid affecting these devices.
Innovation Solution
A channel access method involving fixed duration-based attempts for transmission in unlicensed bands, where a user equipment (UE) or base station attempts a second fixed duration-based channel access if the initial attempt fails, with the first fixed duration being shorter than the second, allowing transmission after the duration if the channel is idle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single fixed duration-based channel access is used, then the channel access process is simple, but the reliability of transmission in unlicensed bands is insufficient due to potential interference
Solution Approach 1:
The channel access process is segmented into multiple fixed duration-based attempts. The method divides the access procedure into a first fixed duration-based channel access attempt and a second fixed duration-based channel access attempt, allowing the system to retry transmission after a predetermined period if the first attempt fails, thereby improving reliability without requiring complex adaptive algorithms
Solution Approach 2:
The method performs preliminary channel access attempts within fixed durations before allowing transmission. By conducting the first fixed duration-based channel access and, if necessary, the second fixed duration-based channel access in advance with predetermined time limits, the system ensures reliable channel access while maintaining process simplicity through pre-defined protocols
2Reliability
If multiple channel access attempts are made, then the reliability of transmission is improved, but the time required for channel access increases
Solution Approach 1:
The channel access method implements dynamic time management through fixed duration-based attempts. The system uses a first fixed duration for the first channel access attempt and a second fixed duration for the second attempt, adjusting the total access time based on whether retries are necessary. This dynamic approach ensures reliable access when needed while minimizing time consumption when successful access occurs on the first attempt
Solution Approach 2:
The method employs periodic fixed duration intervals for channel access attempts. By using predetermined fixed durations for each attempt rather than continuous or variable time intervals, the system creates a periodic access pattern that improves reliability through structured retries while keeping the time overhead predictable and limited to specific fixed intervals
3Object-affected harmful factors
If fixed duration-based channel access is used, then the coexistence with existing wireless devices is improved, but the adaptability to varying channel conditions is reduced
Solution Approach 1:
The method uses parameter changes through fixed duration values to balance coexistence and adaptability. By defining specific fixed durations for channel access attempts, the system provides sufficient time for existing wireless devices to complete their operations, reducing interference. Meanwhile, the predetermined nature of these durations allows for consistent and predictable behavior that adapts sufficiently to varying channel conditions without requiring complex real-time adjustments
Data Source
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AI summary
A base station of a wireless communication system is disclosed. The base station of wireless communication includes a communication module and a processor. The processor is configured to receive a grant for scheduling a plurality of uplink transmissions from the base station, and when the UE attempts to a first fixed duration-based channel access for a first transmission which is one of the plurality of uplink transmission and fails in the first fixed duration-based channel access, attempt to a second fixed duration-based channel access for a second transmission which is a transmission following the first transmission.