Unlicensed-Band D2D Terminal Timing After LBT Success
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Solution Overview
Problem
In D2D communication using higher frequency bands, LBT failures in the unlicensed band can lead to resource wastage.
Innovation Solution
A terminal is equipped with a reception unit for performing LBT, a control unit for mapping transmissions to optimal start times, and a transmission unit for initiating transmissions immediately after successful LBT, applying a part of the signal structure to later timings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT is performed in unlicensed band for D2D communication, then channel access compliance is improved, but transmission resource utilization deteriorates due to LBT failures
Solution Approach 1:
The transmission resource is segmented into multiple candidate timings within a transmission time interval. Instead of attempting a single transmission that may fail due to LBT, the system divides the transmission opportunity into multiple discrete timing options, allowing the terminal to select the most appropriate timing based on LBT outcomes and resource availability.
Solution Approach 2:
The signal structure is made dynamic by allowing different portions to be applied at different timings. The control unit applies a part of the signal structure from the first timing to subsequent timings, enabling flexible adaptation to changing channel conditions and LBT results, thereby improving resource utilization while maintaining compliance.
2Device complexity
If transmission is delayed to align with scheduled timings, then resource allocation simplicity is improved, but transmission latency increases when LBT succeeds earlier
Solution Approach 1:
Multiple candidate timings are predetermined within the transmission time interval before actual transmission occurs. This preliminary setup of multiple timing options allows the terminal to act quickly when LBT succeeds, selecting the earliest appropriate timing rather than waiting for a fixed scheduled time, thus reducing latency while maintaining structured resource allocation.
3Reliability
If entire signal structure is transmitted from first timing, then transmission completeness is improved, but resource efficiency deteriorates when only partial transmission is needed at later timings
Solution Approach 1:
The control unit extracts and applies only the necessary portion of the signal structure from the first timing to subsequent timings. Instead of transmitting the entire signal structure repeatedly, the system takes out and applies only the relevant part, improving resource efficiency while ensuring transmission completeness through progressive application across multiple timings.
Data Source
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AI summary
A terminal includes: a reception unit configured to perform an LBT (Listen before talk) for a certain transmission in an unlicensed band; a control unit configured to map the certain transmission to a resource, based on a plurality of timings in which a transmission can be started; and a transmission unit configured to start the certain transmission from a timing in which a transmission can be started, the timing being located immediately after the LBT is successful. The control unit applies a part of a signal structure of the certain transmission in a first timing among the plurality of timings in which a transmission can be started to a transmission in a second or later timing among the plurality of timings in which a transmission can be started.