Terminal LBT Without Random Backoff for D2D COT Sharing
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Solution Overview
Problem
In newly-operated higher frequency bands, device-to-device (D2D) communication in unlicensed bands faces challenges with Listen Before Talk (LBT) failures due to multiple terminals attempting transmissions during Channel Occupancy Time (COT) sharing.
Innovation Solution
A terminal is configured to perform LBT without random backoff immediately after a first signal related to D2D direct communication in an unlicensed band, and to transmit a second signal if the LBT is successful, with a configured Cyclic-Prefix extension (CPE) length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple terminals perform LBT with random backoff during COT sharing in unlicensed band, then channel access compliance is improved, but LBT failure rate increases
Solution Approach 1:
The patent applies preliminary action by having the first terminal perform LBT with random backoff to acquire COT before other terminals attempt transmissions. Subsequent terminals within the COT perform LBT without random backoff, leveraging the preliminary channel acquisition to improve their LBT success rates while maintaining regulatory compliance.
Solution Approach 2:
The patent segments the channel access process into two phases: initial COT acquisition phase where random backoff is applied, and subsequent COT sharing phase where random backoff is omitted. This segmentation allows different LBT strategies to be applied at different stages, improving overall transmission efficiency while maintaining reliability.
2Reliability
If LBT with random backoff is performed by each terminal during COT sharing, then channel access regulation compliance is improved, but transmission delay increases
Solution Approach 1:
The first terminal performs the time-consuming LBT with random backoff as a preliminary action to secure the COT. This preliminary channel acquisition eliminates the need for subsequent terminals to perform identical time-consuming LBT procedures, reducing overall transmission delay while maintaining regulatory compliance through the initial proper LBT execution.
3Productivity
If COT sharing is implemented in unlicensed band D2D communication, then spectrum utilization is improved, but LBT failure risk increases
Solution Approach 1:
The patent uses preliminary action by having one terminal successfully acquire COT through LBT with random backoff before other terminals share the channel. This preliminary successful channel acquisition creates a reliable foundation for subsequent COT sharing, improving overall LBT success rates while enabling better spectrum utilization through multiple terminal access.
Data Source
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AI summary
A terminal includes: a control unit configured to perform an LBT (Listen before talk) without a random backoff immediately after a first signal related to device-to-device direct communication that is transmitted in a COT (Channel occupancy time) obtained by one of terminals in an unlicensed band; and a transmission unit configured to transmit a second signal in a case where the LBT is successful. The control unit configures a CPE (Cyclic-Prefix extension) length that is applied to the second signal.