Joint Chirp Packet Decoding for Low-Power LPWAN Coverage
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Solution Overview
Problem
Low Power Wide Area Networks (LPWANs) face challenges in maintaining battery life and coverage for devices located in urban areas due to signal attenuation and the lack of synchronization, leading to devices being out of range or battery-deprived, especially in unplanned and user-deployed networks.
Innovation Solution
The implementation of a joint decoding system using chirp spread-spectrum modulation, where gateway devices demodulate signals and combine time-adjacent chirps to enhance signal-to-noise ratio, allowing for coherent combining of weak signals across multiple gateways in the cloud, thereby improving battery life and network coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If devices transmit signals at higher power to overcome attenuation, then communication range is improved, but battery life deteriorates
Solution Approach 1:
The patent combines signals from multiple gateways through coherent combining at the cloud server. By merging multiple weak received signals that have the same packet content, the system achieves signal amplification without requiring individual devices to transmit at high power, thus extending communication range while preserving battery life
Solution Approach 2:
The patent introduces a new dimension of signal processing by moving from single-gateway reception to multi-gateway coherent combining. Instead of solving the power-range tradeoff at the device level, the system resolves it by adding spatial diversity across multiple gateways and performing joint decoding in the cloud, effectively transforming a 1D problem into a multi-dimensional solution
2Area of stationary object
If more gateways are deployed to improve coverage, then network coverage is improved, but system complexity deteriorates
Solution Approach 1:
The patent segments the signal processing function across multiple independent gateways and the cloud server. Each gateway independently receives and demodulates signals without needing to coordinate with other gateways, while the cloud server handles the complex joint decoding. This segmentation allows network coverage to expand with more gateways while keeping individual gateway complexity low
Solution Approach 2:
The cloud server acts as an intermediary that coordinates the distributed gateways. It collects demodulated data from multiple gateways, performs joint decoding, and manages the coherent combining process. This intermediary abstraction layer simplifies the overall system architecture by centralizing the complex coordination logic while allowing gateways to remain simple and scalable
3Measurement precision
If gateway devices perform full packet decoding, then decoding accuracy is improved, but energy consumption deteriorates
Solution Approach 1:
The patent applies partial action by having gateways perform only demodulation and partial decoding of packet headers, rather than full packet decoding. Gateways identify potential packets and extract sufficient information to request data from the cloud server, leaving the complete decoding process to be performed jointly in the cloud where more computational resources are available
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.