Multi-Dimensional Spread Spectrum Modulation for Narrow Bandwidth Data Rates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The narrow frequency bandwidth in the 868.0 MHz to 868.6 MHz band limits data rates in wireless communication systems, with prior art implementations achieving significantly lower data rates than the theoretical maximum of 250 kbps due to constraints in spreading gain and data rate, necessitating a method to enhance transmission efficiency.
Innovation Solution
A modulation scheme utilizing highly auto-correlated spread code sequences for determining delays in signal spreading, combined with phase shift keying and quadrature phase shift keying, allows for increased data rates by effectively utilizing the available frequency band and ensuring compatibility with legacy systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spread spectrum techniques are used to achieve resistance to interference and noise, then reliability is improved, but data rate is reduced due to narrow frequency bandwidth
Solution Approach 1:
The patent transitions from traditional single-dimension spread spectrum modulation to a multi-dimensional approach by combining frequency hopping with code division multiplexing. This allows the system to exploit both frequency domain (hopping patterns) and code domain (spreading sequences) dimensions simultaneously, achieving enhanced reliability without sacrificing data rate in narrow bandwidth conditions
2Device complexity
If simple modulation schemes are used in narrow bandwidth, then device complexity is reduced, but data rate is limited
Solution Approach 1:
The patent segments the data stream into multiple parallel channels, each modulated with different spreading codes and frequency hopping patterns. This segmentation allows independent optimization of each channel while collectively achieving high aggregate data rates, effectively bypassing the limitation of simple modulation schemes in narrow bandwidth
3Reliability
If spreading gain is increased to improve signal quality, then reliability is improved, but data rate is reduced
Solution Approach 1:
The patent dynamically adjusts multiple parameters including spreading code length, frequency hopping rate, and modulation order based on channel conditions. This allows the system to optimize the balance between spreading gain and data rate in real-time, achieving high signal quality without permanently sacrificing data transmission capacity
Data Source
AI summary
A method and a device are described for determining data from a signal spread over at least one frequency base band representing the data. The method for generating a signal has a step of using at least one highly auto-correlated spread code sequence (1C, 2C) associated with the frequency base band for determining a delay with which a modulated portion (1P, 2P) of the data is spread on the signal. The method has further steps of determining said modulated portion from the signal using the delay and the spread code sequence (1C, 2C), of demodulating the modulated portion (1P, 2P) using phase shift keying, and of determining a remainder (1R, 2R) of the data using the delay.