Sidelink Synchronization Power Control in Unlicensed Spectrum
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Solution Overview
Problem
In sidelink communication using unlicensed spectrum, ensuring stable channel transmit power to avoid communication interruptions and improve transmission performance is a challenge.
Innovation Solution
Determine a first frequency domain resource set for synchronization signals within a bandwidth part, set transmit power based on maximum device power and a parameter, and constrain the frequency of synchronization signals to maintain power stability and optimize transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the terminal contends for channel through listen-before-talk (LBT) and shares channel resource with another terminal, then spectrum utilization is improved, but transmit power stability deteriorates due to power fluctuations during synchronization
Solution Approach 1:
The patent applies preliminary action by determining and reserving a specific frequency domain resource set for synchronization signals before actual data transmission begins. The synchronization signal is transmitted at a predetermined power level (PCMAX - Δ) in advance, establishing a stable reference before channel contention and data transmission occur. This pre-established synchronization prevents power fluctuations during subsequent LBT-based channel sharing operations.
Solution Approach 2:
The patent segments the frequency domain resources by separating synchronization signal resources from data transmission resources. Specifically, it divides the bandwidth part into M frequency domain resource sets, designating the first frequency domain resource set exclusively for synchronization signals while other sets are used for data transmission. This segmentation isolates synchronization power requirements from variable data transmission power, maintaining overall transmit power stability.
2Device complexity
If transmit power for synchronization signal fluctuates, then device complexity is reduced by allowing dynamic power adjustment, but communication reliability deteriorates due to frequent synchronization source switching
Solution Approach 1:
The patent applies parameter changes by introducing a specific power offset parameter Δ (where Δ = A and A = 10 log10(Q)) that modifies the synchronization signal power from the maximum PCMAX to a controlled level PCMAX - Δ. This parameter change stabilizes the transmit power for synchronization signals while maintaining sufficient signal quality, preventing frequent synchronization source switching and improving communication reliability without excessive device complexity.
3Productivity
If the terminal uses multiple frequency domain resource sets for data transmission, then transmission capacity is improved, but power distribution complexity increases making it difficult to maintain stable transmit power
Solution Approach 1:
The patent applies local quality by assigning different power characteristics to different frequency domain resource sets. The first frequency domain resource set is designated with specific power characteristics (for synchronization signals at power level PCMAX - Δ), while other frequency domain resource sets are allocated for data transmission with appropriate power levels. This localized power assignment simplifies overall power distribution by providing clear, differentiated power rules for each resource set type.
Data Source
AI summary
This application provides communication methods and apparatuses. An example method includes determining a first frequency domain resource set in a first time unit, determining a transmit power for a first message based on a maximum transmit power of a first device and a first parameter, and sending the first message in the first time unit based on the transmit power for the first message. The transmit power for the first message does not exceed a difference between the maximum transmit power of the first device and the first parameter. The first frequency domain resource set includes a frequency domain resource of a synchronization signal used for synchronization. The first frequency domain resource set is included in M frequency domain resource sets that carry the first message.