D2D and D2C Signal Handling in LTE Subframes
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Solution Overview
Problem
In LTE systems, device-to-device (D2D) and device-to-cellular (D2C) signals often overlap, leading to incorrect transmission and reception due to differing timing alignments and potential power level issues when transmitted simultaneously, causing interference and incomplete signal transmission.
Innovation Solution
A method where a communication device transmits either the D2D signal or the D2C signal in a subframe, avoiding overlap by not transmitting both signals simultaneously, and reserving resources for D2C signals that include sounding reference signals, ensuring proper timing alignment with DL and UL communications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a UE transmits both D2D signal and D2C signal simultaneously in the same subframe, then communication efficiency is improved, but signal transmission reliability deteriorates due to timing misalignment and power level conflicts
Solution Approach 1:
The patent segments the transmission resources by separating D2D signals and D2C signals into different subframes. The method determines whether to transmit D2D or D2C signals based on subframe type (MBSFN or non-MBSFN), thereby dividing the transmission timeline into distinct segments that avoid simultaneous transmission conflicts and ensure reliable signal delivery.
2Adaptability or versatility
If D2D communication and D2C communication use different timing alignments, then each communication type can operate independently, but signal collision occurs when both are transmitted in overlapping subframes
Solution Approach 1:
The patent extracts D2D signals from subframes that are also used for D2C transmissions. Specifically, D2D signals are transmitted only in MBSFN subframes while D2C signals use non-MBSFN subframes, thereby removing the harmful overlap between the two communication types and eliminating signal collision.
3Power
If total transmit power level exceeds UE power limit during simultaneous D2D and D2C transmission, then communication capacity is maximized, but signal transmission completeness deteriorates
Solution Approach 1:
The patent performs preliminary determination of the subframe type (MBSFN or non-MBSFN) before signal transmission. Based on this preliminary classification, the UE decides whether to transmit D2D signals, D2C signals, or both in different subframes, thereby proactively managing power allocation and avoiding the harmful effect of exceeding power limits during simultaneous transmission.
Data Source
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AI summary
A method of handling a device-to-device, D2D, signal and a device-to-cellular, D2C, signal for a first communication device comprises communicating with a second communication device according to a D2D communication; communicating with a network according to a D2C communication; and transmitting one of the D2D signal and the D2C signal in a subframe, wherein the D2D signal and the D2C signal are transmitted to the second communication device and the network, respectively.