Device-to-Device Preamble Synchronization for Low-Power Emergency Messaging
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Solution Overview
Problem
User equipment devices (UE) that are off-grid face challenges in transmitting wireless data efficiently and power-efficiently to other UE devices due to timing drift and the need for continuous receiver activation, which leads to excessive power consumption.
Innovation Solution
UE devices transmit device-to-device (D2D) signals with preambles that precede emergency messages, allowing the receiving UE device to synchronize its timing and activate the receiver only during specific windows to conserve power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the receiver is continuously activated to receive D2D signals, then reliable data reception is achieved, but power consumption increases significantly
Solution Approach 1:
The receiver is activated periodically during specific RX windows rather than continuously. The second UE device activates its receiver only during predetermined receiver windows to listen for preambles and messages, then deactivates it to conserve power. This periodic activation pattern resolves the contradiction by maintaining reliable reception during critical periods while minimizing power consumption during idle periods.
Solution Approach 2:
A preamble sequence is transmitted before the actual data message to enable the receiver to activate at the precise moment when data will be transmitted. The first UE device sends a preamble that indicates the timing of the subsequent message, allowing the second UE device to activate its receiver in advance of the actual data transmission, ensuring reliable reception without continuous activation.
2Stability of the object's composition
If timing synchronization is maintained without preambles, then continuous communication is possible, but the receiver must remain active constantly leading to power drain
Solution Approach 1:
The preamble serves as a preliminary action that establishes timing synchronization before actual data transmission. By receiving and processing the preamble during a brief RX window, the second UE device synchronizes its timing to the first UE device, then can remain inactive until the next predetermined transmission time, avoiding continuous power consumption while maintaining synchronization stability.
Solution Approach 2:
The system uses the transmitted preamble itself to carry timing synchronization information that enables the receiver to self-synchronize. The preamble contains timing information that allows the second UE device to automatically align its reception timing with the first UE device's transmission timing without requiring continuous active monitoring, thus maintaining synchronization stability with minimal power consumption.
3Use of energy by moving object
If the receiver is deactivated between RX windows, then power is conserved, but timing drift may occur affecting subsequent message reception
Solution Approach 1:
The preamble transmitted before each message serves as a refresh of timing synchronization information. Even though the receiver is deactivated between RX windows, the preamble received during each window re-establishes the timing reference, compensating for any drift that occurred during the inactive period and ensuring accurate message reception.
Solution Approach 2:
The preamble provides feedback information about the transmitter's timing reference to the receiver. By analyzing the preamble's timing characteristics, the second UE device can adjust its local timing to match the first UE device's timing, compensating for drift accumulated during the receiver's inactive period and maintaining synchronization stability.
Data Source
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AI summary
A communications network may include user equipment (UE) devices. When a first UE device becomes off-grid and has an emergency message, the first UE device may transmit device-to-device signals for receipt by a second UE device. The signals may include one or more preambles that precede the emergency message and that are used by the second UE device to perform synchronization with the first UE device. The second UE device may periodically activate a receiver during a series of windows to listen for the signals, may receive a preamble sequence during one of the windows, and may synchronize its timing to the first UE device for receipt of the emergency message based on the preamble sequence. This may allow the UE devices to be synchronized for transfer of the emergency message over long distances while consuming a minimal amount of power on the second UE device.