Base Station Relay for D2D Signal Interference Reduction
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Solution Overview
Problem
In LTE networks, device-to-device (D2D) communication using maximum transmit power causes in-band interference, reducing signal coverage and reception area due to strong interference with base station uplink signals, limiting the effective range of D2D signals.
Innovation Solution
Configuring separate resource pools in uplink and downlink frequencies by the base station to relay and forward D2D signals, allowing UE to operate at lower power while expanding the D2D signal reception area without maximum transmit power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the UE uses maximum transmit power to send a D2D signal, then the D2D communication distance is extended, but strong in-band interference is caused to the base station uplink signal
Solution Approach 1:
The base station acts as an intermediary to receive the D2D signal from the first UE and forward it to the second UE. This mediator approach allows the UEs to communicate without needing to transmit at maximum power directly to each other, thereby reducing in-band interference to the base station uplink while maintaining extended communication coverage through the base station's relay function.
Solution Approach 2:
Instead of the second UE receiving the D2D signal directly from the first UE in a traditional peer-to-peer manner, the signal transmission path is inverted: the base station receives the signal from the first UE and then sends it to the second UE. This inversion of the transmission path allows power control to be applied, reducing interference while maintaining communication effectiveness.
2Object-generated harmful factors
If the transmit power of the UE is reduced to decrease in-band interference, then the interference to the base station uplink signal is reduced, but the signal coverage area is reduced
Solution Approach 1:
The base station serves as a mediator that receives signals from UEs at reduced power levels and forwards them with sufficient power to cover the required area. This allows the UE to operate at lower power (reducing interference) while the base station ensures adequate coverage area by relaying the signal with appropriate power levels.
Solution Approach 2:
The base station performs multiple functions: it acts as both an uplink receiver for normal cellular communication and as a relay node for D2D communication. This multi-functionality allows the system to maintain signal coverage area through the base station's relay capability while UEs operate at reduced power levels, thus reducing in-band interference.
3Length of moving object
If the UE uses maximum transmit power for D2D communication, then farthest-distance D2D communication is achieved, but the uplink signal received by the base station is submerged in in-band interference
Solution Approach 1:
The base station acts as an intermediary receiver for D2D signals, separating the D2D communication path from the uplink path. By receiving D2D signals from UEs and then forwarding them to destination UEs, the base station prevents strong D2D transmit power from submerging the uplink signal, thereby maintaining uplink signal quality while still enabling long-distance D2D communication.
Solution Approach 2:
The communication system is segmented into separate functional paths: the base station handles uplink communication with UEs, while also serving as a relay for D2D communication between UEs. This segmentation allows maximum D2D transmit power to be used for distance extension without compromising uplink signal quality, as the two communication types are handled through separate functional segments of the system.
Data Source
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AI summary
A signal transmission method, a base station, and user equipment are disclosed. The method includes: configuring, by a base station, a first resource pool in an uplink frequency; configuring, by the base station, a second resource pool in a downlink frequency; receiving, by the base station in the first resource pool, a device-to-device D2D signal sent by first user equipment, where the D2D signal includes one or any combination of a scheduling assignment SA signal, a D2D data signal, or a D2D discovery signal; and sending, by the base station, the D2D signal to second user equipment UE in the second resource pool. In addition, this solution further provides a base station and user equipment.