Relay UE Power Control for D2D Communication
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Solution Overview
Problem
In device-to-device (D2D) communication, relay user equipment (UE) faces challenges in power control due to significant differences in power spectral densities (PSDs) between multiple target receivers, exceeding radio frequency (RF) limitations, especially when communicating with IoT devices and base stations, leading to inefficient power allocation and potential interference.
Innovation Solution
A power control method that determines the priority of target receivers based on estimated PSD differences and pathloss, assigning power accordingly to ensure consistent received power levels, thereby eliminating PSD differences and improving power control efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the relay UE assigns respective powers for transmitting data with allocated PRBs to different target receivers based on pathloss, then the received powers at remote UEs are ensured, but the power spectral density differences become relatively large and exceed RF limitations
Solution Approach 1:
The patent changes the power allocation parameter from individual PRB-level power assignment to subframe-level total power control. By controlling the total power per subframe rather than individual PRB powers, the system maintains received power reliability while reducing power spectral density variations across different PRBs, thereby resolving the RF limitation issue.
2Productivity
If the relay UE transmits data to multiple target receivers simultaneously with different PRBs, then communication efficiency is improved, but power control implementation becomes challenging due to RF limitations
Solution Approach 1:
The patent merges the power control function from individual PRB level to subframe level. Instead of controlling power for each PRB separately, the system controls the total power allocated to all PRBs within a subframe. This consolidation simplifies the power control implementation while maintaining the ability to communicate with multiple target receivers simultaneously.
3Ease of operation
If open loop power control is used for sidelink transmission, then power allocation is simplified, but the transmitted power may not be optimized for different pathloss conditions
Solution Approach 1:
The patent introduces feedback-based closed-loop power control for sidelink transmission. The eNB provides power control commands to the relay UE based on measurements of the actual received power at target receivers. This feedback mechanism allows the system to maintain simple operation while optimizing transmission power efficiency by adjusting power allocation according to actual pathloss conditions and receiver requirements.
Data Source
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AI summary
There are provided a communication apparatus and a method. The communication apparatus comprising : a circuitry operative to determine respective priorities of a plurality of target receivers to which data is transmitted, and assign power for transmitting the data at least according to a power loss feature related to a particular target receiver of which the priority is the highest or is higher than a power threshold; and a transmitter, operative to transmit, to the plurality of target receivers, the data with the assigned power.