Asymmetric Preamble Lengths in LoRa Gateway-Device Communication
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Solution Overview
Problem
Existing LoRa communication systems face high power consumption in bidirectional data interaction scenarios, particularly in terminal devices that frequently transmit data, due to the traditional equal preamble lengths used in wireless communication, which leads to inefficient power usage and limited capacity for multiple terminal devices to connect to a single gateway.
Innovation Solution
The communication method involves a terminal device transmitting a second packet with a shorter preamble compared to the first packet received from a gateway device, allowing for reduced power consumption and increased channel efficiency, with the terminal device sleeping for a longer duration and performing channel activity detection for a shorter duration to ensure timely data reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If terminal devices use equal preamble lengths for transmission and reception in bidirectional communication, then communication reliability is maintained, but power consumption increases significantly
Solution Approach 1:
The patent applies local quality by differentiating preamble lengths based on communication direction: longer preambles for gateway-to-terminal transmission (downlink) and shorter preambles for terminal-to-gateway transmission (uplink). This localized optimization allows the system to maintain reliability where needed (downlink with longer preamble) while reducing power consumption where possible (uplink with shorter preamble), directly resolving the contradiction between power efficiency and communication reliability.
Solution Approach 2:
The patent changes the parameter of preamble length based on communication direction and device role. By setting different preamble lengths (first preamble length for downlink, second preamble length for uplink) rather than using a fixed equal length, the system optimizes power consumption while maintaining reliability. The terminal device uses the shorter second preamble for uplink transmission, directly reducing its power consumption compared to using equal preambles.
2Reliability
If terminal devices transmit with longer preambles to ensure reliable detection, then communication reliability improves, but channel capacity for multiple devices decreases
Solution Approach 1:
The patent applies local quality by assigning different preamble lengths to different communication directions: the gateway uses longer first preambles for downlink transmission to ensure terminal devices can reliably detect and receive data, while terminal devices use shorter second preambles for uplink transmission. This differentiated approach ensures detection reliability where it matters most (downlink from gateway) while increasing channel capacity by reducing the time each terminal occupies the channel during uplink transmission, allowing more devices to communicate simultaneously.
3Speed
If terminal devices frequently wake up to detect channels for real-time communication, then response time improves, but power consumption increases
Solution Approach 1:
The patent applies preliminary action by having the gateway device transmit data with a long first preamble during periods when terminal devices are sleeping. The terminal device only needs to wake up briefly to detect the channel activity and receive the already-transmitted data, rather than continuously monitoring. This approach ensures real-time data delivery (improved response time) while minimizing the terminal's active detection time, thereby reducing power consumption.
Solution Approach 2:
The patent implements periodic action through the terminal device's sleep-wake cycle for channel detection. Instead of continuous monitoring, the terminal periodically wakes up to detect channel activity for a short duration (using the shorter second preamble for response) and then returns to sleep mode. This periodic detection strategy maintains real-time communication capability while significantly reducing power consumption compared to continuous monitoring.
Data Source
AI summary
The present disclosure provides a communication system, a gateway device, a terminal device and a communication method. The communication method includes: receiving, by a terminal device, a first packet from a gateway device, the first packet including a first preamble; transmitting, by the terminal device, a second packet to the gateway device, the second packet including a second preamble, a length of the first preamble is greater than a length of the second preamble.