Constellation-Aided LoRa Modulation for Distance–Rate Balance
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Solution Overview
Problem
Existing LoRa-based signal transmission techniques suffer from low signal transmission rates due to the limitations imposed by the spreading factor, which affects the balance between transmission distance and signal rate.
Innovation Solution
The proposed CA-LoRa method involves generating a LoRa signal set through Gray mapping and PSK constellation mapping, followed by PSK modulation using a preset imaginary unit and PSK constellation points, and performing real-imaginary part judgment on a complex number sequence to enhance transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the spreading factor (SF) is increased to extend transmission distance, then the transmission distance is improved, but the signal transmission rate deteriorates
Solution Approach 1:
The patent merges LoRa modulation with PSK (Phase Shift Keying) modulation to create a hybrid modulation scheme. By combining the long-range capabilities of LoRa with the higher-order modulation efficiency of PSK, the system achieves both extended transmission distance and improved transmission rate simultaneously, resolving the contradiction between distance and speed.
Solution Approach 2:
The patent changes the modulation parameter by introducing PSK constellation mapping into the LoRa signal structure. This parameter change allows the system to transmit additional information bits per symbol without increasing the spreading factor, thereby improving transmission rate while maintaining the transmission distance benefits of high SF values.
2Reliability
If the spreading factor (SF) is increased to ensure reliable transmission, then the transmission reliability is improved, but the data transmission efficiency deteriorates
Solution Approach 1:
The patent combines LoRa's reliable spread spectrum modulation with PSK's efficient constellation mapping. The LoRa component ensures reliable transmission through spread spectrum processing, while the PSK component increases data efficiency by encoding multiple bits per symbol through constellation points, thus achieving both reliability and productivity.
Solution Approach 2:
The patent adds another dimension to the signal by introducing phase modulation through PSK constellation mapping. This dimensional addition allows the system to encode information not only through the LoRa spreading sequence but also through the phase characteristics of the modulated signal, thereby increasing data efficiency without compromising reliability.
Data Source
AI summary
A signal transmission method based on constellation-aided LoRa modulation includes: a modulated bit sequence and a phase shift keying (PSK) bit sequence are obtained, and the modulated bit sequence is subjected to Gray mapping and spread spectrum modulation to generate a LoRa signal set; the PSK bit sequence is subjected to PSK constellation mapping based on a preset constellation point coordinate set to output a PSK constellation point set; the LoRa signal set is subjected to PSK modulation based on a preset imaginary unit and the PSK constellation point set to generate a transmission signal; a complex number sequence is generated based on the transmission signal and a preset raw down chirp signal; and real-imaginary part judgment is performed on the complex number sequence to output a LoRa modulation information sequence set and a PSK symbol judgment result. A signal transmission system based on CA-LoRa is further provided.