Joint Chirp Packet Decoding for Weak LPWAN Signal Coverage
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Solution Overview
Problem
Low Power Wide Area Networks (LPWANs) face challenges in maintaining connectivity and battery life for devices in urban environments due to signal attenuation and the lack of synchronization, leading to devices being out of range or battery-deprived, especially in unplanned deployments.
Innovation Solution
A method for joint decoding of packets using chirp spread-spectrum modulation, where gateway devices identify and transport weak signals to the cloud for coherent combining across multiple gateways, expanding network coverage and improving battery life by leveraging geographical diversity and reducing noise resistance through data symbol processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If devices transmit signals from deep urban areas or remote neighborhoods, then network coverage is improved, but signal attenuation increases causing severe battery drain
Solution Approach 1:
The patent combines signals from multiple gateway devices through coherent combining at a remote server. By merging weak signals from multiple gateways that received the same transmission, the system achieves successful decoding without requiring the transmitting device to increase power, thus expanding effective coverage while maintaining low energy consumption.
Solution Approach 2:
The remote server acts as an intermediary that collects and processes signals from multiple gateway devices. It performs coherent combining of weak signals and joint decoding, enabling devices in deep urban areas to communicate effectively without increasing their transmission power or battery consumption.
2Area of stationary object
If multiple gateway devices are deployed to expand coverage, then network reach is improved, but coordination and synchronization between gateways becomes more complex
Solution Approach 1:
The patent extracts the complex signal processing and coordination functions from individual gateway devices and centralizes them at a remote server. Gateway devices simply forward received signals to the server, which performs coherent combining and joint decoding. This reduces gateway complexity while enabling multi-gateway coordination for expanded coverage.
Solution Approach 2:
The remote server serves as an intermediary that manages the complexity of coordinating multiple gateway devices. It handles signal alignment, coherent combining, and joint decoding, allowing gateway devices to operate independently with minimal coordination overhead while still achieving improved network coverage.
3Reliability
If devices wake up periodically to synchronize with the network, then network synchronization is improved, but battery life is reduced
Solution Approach 1:
The patent enables devices to transmit data without periodic wake-ups for synchronization. By using asynchronous transmission with unique device identifiers and employing joint decoding at the remote server, devices can remain in low-power sleep mode longer, extending battery life while maintaining network functionality.
Solution Approach 2:
The system uses feedback mechanisms where the remote server acknowledges received transmissions and devices can adjust their transmission timing based on this feedback. This allows devices to maintain network synchronization without frequent wake-ups, balancing synchronization reliability with extended battery life.
Data Source
AI summary
A method of providing wireless communications in a wireless network can include wirelessly receiving a chirp spread-spectrum modulated signal at a first gateway device, the chirp spread-spectrum modulated signal being transmitted by a remote client device. The chirp spread-spectrum modulated signal can be demodulated at the first gateway device to provide demodulated data at the first gateway device. The demodulated data can be processed to provide an indication that a decode of a packet including the demodulated data failed. Time adjacent chirps included in the demodulated data can be combined to provide combined data at the first gateway device. A message can be transmitted from the first gateway device to a remote server responsive to an amplitude of the combined data exceeding a threshold value and the indication that the decode of the packet including the demodulated data failed.