Sidelink Transmit Power Control Using Downlink Pathloss
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing downlink pathloss for sidelink transmission power control in device-to-device communication, particularly in high-frequency bands where beamforming is complex and limited by the number of concurrent high-gain beams, leading to reduced coverage and increased interference.
Innovation Solution
A method and apparatus that derive a downlink pathloss value to determine sidelink transmit power, allowing devices to perform sidelink transmission with optimized power control, enhancing coverage and reducing interference by using both DL and SL pathloss estimates for open-loop power control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If beamforming is used in high-frequency bands, then directional gain is improved, but the number of concurrent high-gain beams is limited causing reduced coverage and increased interference
Solution Approach 1:
The patent segments the pathloss estimation into two independent components: downlink pathloss (from base station to device) and sidelink pathloss (from device to device). This segmentation allows the system to use different pathloss estimates for different transmission directions, enabling better power control without requiring multiple concurrent high-gain beams, thus maintaining coverage area while preserving directional gain where needed.
2Illumination intensity
If beamforming is used in high-frequency bands, then directional gain is improved, but interference is increased
Solution Approach 1:
The patent implements a feedback mechanism where the receiving device measures the sidelink pathloss and reports it back to the transmitting device. This feedback enables the transmitting device to adjust its sidelink transmit power based on actual channel conditions, reducing interference to other devices while maintaining the directional gain benefits of beamforming for the intended receiver.
3Ease of operation
If downlink pathloss is used for sidelink power control, then power control simplicity is improved, but accuracy is reduced
Solution Approach 1:
The patent merges two pathloss estimation approaches: downlink pathloss (which is simple to obtain) and sidelink pathloss (which is more accurate for device-to-device communication). The final sidelink transmit power is determined by combining these estimates, thereby maintaining the simplicity of using downlink pathloss while improving accuracy through the additional sidelink pathloss measurement.
Data Source
AI summary
A method and apparatus are disclosed from the perspective of a device to perform sidelink transmission. The method includes the device being in RRC (Radio Resource Control)-connected mode in Uu link. The method also includes the device being configured to use at least DL (Downlink) pathloss for sidelink power control. The method further includes the device deriving a first DL pathloss value for determining an uplink transmit power of one specific kind of uplink transmission. In addition, the method includes the device determining or deriving a sidelink transmit power based on the first DL pathloss value. Furthermore, the method includes the device performing a sidelink transmission to other device(s) with the sidelink transmit power.