D2D Terminal LBT Scheduling for Overlapping Signal Transmissions
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Solution Overview
Problem
In newly-operated frequency bands with higher frequencies, performing device-to-device direct communication in an unlicensed band requires adapting Listen Before Talk (LBT) operations, which can overlap with transmission times, necessitating improved LBT methods.
Innovation Solution
A terminal is equipped with a control unit to perform LBT for subsequent signals while avoiding LBT during the transmission of initial signals, ensuring successful channel access in the unlicensed band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LBT is applied for multiple D2D transmissions, then channel access compliance is ensured, but transmission efficiency deteriorates due to overlapping LBT requirements
Solution Approach 1:
The patent merges multiple LBT operations into a single LBT procedure when the transmission intervals fall within the same slot. By combining the LBT requirements for multiple D2D transmissions into one unified channel access check, the system maintains compliance with unlicensed band regulations while eliminating redundant LBT operations that would otherwise reduce transmission efficiency.
Solution Approach 2:
The patent dynamically adjusts the LBT execution strategy based on the timing relationship between D2D transmissions. When transmissions are scheduled within the same slot, the system dynamically decides to perform only one LBT operation. When transmissions are separated by different slots, the system dynamically performs LBT for each slot, optimizing channel access compliance while minimizing unnecessary LBT overhead.
2Reliability
If LBT is performed for each D2D signal transmission, then regulatory compliance is improved, but time consumption increases due to overlapping LBT periods
Solution Approach 1:
The patent combines multiple LBT execution instances into a single LBT operation when the corresponding D2D transmissions are scheduled within the same time slot. This merging approach ensures that regulatory compliance is maintained through proper channel sensing, while simultaneously reducing the total time consumption by eliminating redundant LBT periods that would otherwise overlap or consecutively occur.
3Measurement precision
If multiple LBT operations are performed for sequential D2D transmissions, then channel sensing accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements a dynamic LBT execution mechanism that adapts to the scheduling conditions of D2D transmissions. The system evaluates the timing relationship between sequential transmissions and dynamically determines the number of LBT operations required. This dynamic approach maintains channel sensing accuracy by performing LBT when necessary, while reducing device complexity by avoiding unnecessary LBT operations and associated processing overhead.
Solution Approach 2:
The patent merges redundant LBT operations into a single channel sensing event when multiple D2D transmissions are scheduled within the same slot. This merging strategy preserves measurement precision by ensuring that the channel is properly sensed before transmission, while simultaneously reducing device complexity by eliminating duplicate sensing and control operations that would increase processing burden.
Data Source
AI summary
A terminal includes: a control unit configured to, when transmitting a first signal related to a device-to-device direct communication, perform an LBT (Listen before talk) for transmitting a second signal to be transmitted after the first signal; and a transmission unit configured to transmit at least the second signal in a case where the LBT is successful. In a case where a duration of the LBT overlaps with the first signal in a time domain, the control unit does not perform an LBT during a time period in which the first signal is transmitted.