PN-Code Tone Signal Receiver for Overlapping LPWAN Packets
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Solution Overview
Problem
Wireless network devices face challenges in differentiating and decoding overlapping packets received at the same time, leading to difficulties in accurately transmitting and receiving data.
Innovation Solution
The implementation of a transmitter/receiver architecture that uses pseudo-noise (PN) codes to modulate and demodulate tone signals, allowing the receiver to identify and separate packets by scanning for repeating preambles and syncwords, and applying an iterative subtraction process to reconstruct and decode overlapping packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional wireless receiver architecture is used, then device complexity is low, but the ability to differentiate and decode overlapping packets from multiple transmitters is insufficient
Solution Approach 1:
The receiver architecture segments the received signal processing into distinct functional blocks: a buffer stores incoming signals, a packet identifier detects packet boundaries using correlation with known preamble sequences, and a decoder processes individual packets. This segmentation enables the receiver to handle overlapping packets by processing them in discrete, manageable stages rather than as a single complex task.
Solution Approach 2:
The system performs preliminary actions by storing received signals in a buffer before full decoding occurs. The packet identifier operates on the buffered signal to detect packet boundaries and identify packet structures in advance. This preliminary processing prepares the signal for subsequent decoding, allowing the system to differentiate overlapping packets before committing computational resources to full decoding of each packet.
2Productivity
If multiple overlapping packets are decoded, then network capacity increases, but processing time and computational resources increase
Solution Approach 1:
The packet identifier uses periodic correlation with known preamble sequences to detect packet boundaries. By leveraging the periodic structure of packet preambles, the system can efficiently identify packet starts without continuous complex processing. This periodic approach enables the receiver to handle multiple overlapping packets by identifying their boundaries through repeated correlation operations, increasing network capacity while maintaining reasonable processing speeds.
3Measurement precision
If iterative subtraction process is used to separate overlapping packets, then packet decoding accuracy improves, but computational complexity increases
Solution Approach 1:
The iterative subtraction process creates copies of the received signal and subtracts decoded packet representations from these copies. By working with copies rather than the original signal directly, the system can attempt to decode multiple packets independently, then verify and refine decoding results through iterative subtraction. This copying approach improves decoding accuracy by allowing the system to test and validate packet interpretations without permanently altering the original signal data.
Data Source
AI summary
The present disclosure relates to sampling wireless signals received at a receiver. Subsets of the digital samples are multiplied by a Pseudo-Noise (PN) code to generate tone signals. A pattern of tone signals may indicate the presence of a repeating preamble. This may be used to locate a payload that follows the preamble. A tone signal of a payload may be decoded by multiplying a subset of the digital samples with the PN code to generate a tone signal. The tone signal may be transformed into the frequency domain to identify a frequency component having an energy level above a threshold. Using the frequency component, the payload is decoded. By structuring a packet as a series of PN-code modulated tone signals, packets received from different sources may be differentiated even when they arrive at overlapping points of time. This allows for a larger transmitting capacity in a network.