NR Sidelink PSFCH Selection Under Unlicensed-Band Power Limits
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Solution Overview
Problem
The increasing demand for mobile broadband communication and V2X services in wireless communication systems, particularly in unlicensed bands, poses challenges in managing transmit power and channel access to ensure reliable and low-latency sidelink communications.
Innovation Solution
A method and device for determining and performing physical sidelink feedback channel (PSFCH) transmissions on a shared spectrum by prioritizing transmissions based on total transmit power constraints, using interlaces and priority values to optimize power usage and channel access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple PSFCH transmissions are performed simultaneously in unlicensed band, then channel access efficiency and communication reliability are improved, but total transmit power exceeds maximum transmit power
Solution Approach 1:
The patent changes the parameter of transmit power by adjusting the number of PSFCH transmissions (N) based on the ratio between total required power and maximum transmit power. When the ratio exceeds a threshold, the system reduces N to ensure total power remains within maximum limits, thereby resolving the contradiction between maintaining communication reliability and staying within power constraints.
Solution Approach 2:
The patent applies partial action by transmitting only N PSFCHs out of the total required transmissions when power is constrained. Instead of performing all transmissions, the system selectively transmits a subset (N = floor(ratio * M)) to maintain power compliance while still providing partial feedback functionality.
2Power
If the number of PSFCH transmissions is reduced to fit within maximum transmit power, then power constraints are satisfied, but channel access efficiency and communication reliability deteriorate
Solution Approach 1:
The patent introduces dynamic adjustment of the number of PSFCH transmissions based on real-time power conditions. The system calculates the ratio of total required power to maximum transmit power and dynamically determines N accordingly. This dynamic approach allows the system to maximize transmissions within power constraints while maintaining communication reliability as much as possible under given conditions.
Solution Approach 2:
The patent implements feedback mechanisms where the system monitors the power ratio and adjusts the number of transmissions accordingly. By continuously evaluating whether total power exceeds maximum power and adjusting N in response, the system maintains an optimal balance between power compliance and communication reliability through closed-loop control.
3Productivity
If priority-based PSFCH selection is implemented, then power distribution among transmissions is optimized, but system complexity increases
Solution Approach 1:
The patent changes the parameter of transmission selection by introducing priority values associated with each PSFCH transmission. The system sorts transmissions based on priority and selectively transmits the top N prioritized transmissions when power is constrained. This parameter-based selection optimizes power distribution efficiency by ensuring higher priority transmissions are maintained while reducing overall system complexity through a systematic selection criterion.
Data Source
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AI summary
Proposed is an operating method of a first device (100) in a wireless communication system. The method may comprise the steps of: on a shared spectrum, on the basis that the sum of powers for performing one or more PSFCH transmissions is greater than the maximum transmission power of the first device, determining N PSFCH transmissions to be transmitted from among the one or more PSFCH transmissions, wherein transmission power of transmission on at least one first PRB in a first interlace is considered in the total transmission power associated with a plurality of PSFCH transmissions, which are considered in the determination of the N PSFCH transmissions; and performing the N PSFCH transmissions.