D2D Discovery Signal Power Control for Uplink Interference
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Solution Overview
Problem
In LTE and LTE-A systems, device-to-device (D2D) discovery signals interfere with uplink retransmissions in cellular networks, causing interference and collisions, especially when using the same transmission resources, which complicates implementation in existing radio access networks.
Innovation Solution
Wireless devices transmit D2D discovery signals using the same transmission resources as uplink retransmissions to a base station, with the power determined by a control signal from the base station, minimizing interference by prioritizing uplink retransmissions and optimizing power based on channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If D2D discovery signals use the same transmission resources as uplink retransmissions, then resource utilization is improved, but interference and collisions increase
Solution Approach 1:
The patent applies local quality by differentiating transmission power levels for different signal types. D2D discovery signals use a first power level while uplink retransmissions use a second power level, allowing both to coexist on the same resources with appropriate local power differentiation to minimize interference
Solution Approach 2:
The patent changes the power parameter dynamically based on signal type and channel conditions. The network configures power parameters for D2D discovery signals separately from uplink retransmissions, enabling parameter optimization that resolves the interference issue while maintaining resource sharing
2Reliability
If D2D discovery signals are transmitted with high power, then discovery reliability is improved, but interference with uplink retransmissions worsens
Solution Approach 1:
Different power levels are assigned to different signal types locally. D2D discovery signals transmit at a configured first power that provides sufficient reliability for discovery, while uplink retransmissions use a second power level, creating local power quality differentiation that prevents mutual interference
Solution Approach 2:
The network configures appropriate power parameters for D2D discovery signals based on discovery reliability requirements rather than maximizing power. This parameter optimization ensures sufficient discovery reliability while controlling interference to acceptable levels
3Object-affected harmful factors
If separate transmission resources are allocated for D2D discovery signals and uplink retransmissions, then interference is reduced, but resource utilization and system complexity worsen
Solution Approach 1:
The patent merges the transmission resources for D2D discovery signals and uplink retransmissions, allowing both to use the same time-frequency resources. This resource consolidation improves utilization efficiency while the power level differentiation mechanism prevents harmful interference, resolving the contradiction between resource sharing and interference avoidance
Data Source
AI summary
A wireless device transmits a device-to-device discovery signal using the same transmission resource that is used for transmitting uplink retransmissions to a base station by a second wireless device. The device-to-device discovery signal is transmitted at a power that is determined in accordance with a control signal received by the wireless device from the base station. In an example, the wireless device transmits the device-to-device discovery signal on an uplink control channel established for use for sending uplink control signals to the base station.