Multi-Array Receive Beam Sorting for Overlapping Orthogonal Signals
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Solution Overview
Problem
Low-power wide-area networks using orthogonal signaling face challenges with spectral efficiency and multipath propagation in terrestrial use cases, where signals from multiple transmitters can overlap, causing interference and making it difficult to differentiate between symbols from different transmitters.
Innovation Solution
The use of multi-array beamforming techniques, where elongate antenna arrays are oriented perpendicular to each other to create receive beams that detect preamble signals, allowing for time, frequency, and spatial synchronization, and sorting receive beams by path length to differentiate and decode symbols from multiple transmitters, even in the presence of multipath propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If orthogonal signaling is used in terrestrial wireless communication systems, then signal differentiation and decoder complexity are improved, but spectral efficiency deteriorates and multipath interference increases
Solution Approach 1:
The patent segments the received signal processing into multiple receive beams, each handling specific spatial paths. By dividing the signal space into distinct beams and processing them separately, the system can differentiate signals from multiple transmitters while maintaining spectral efficiency through targeted processing of only relevant signal components.
Solution Approach 2:
The patent introduces spatial dimension through multiple antenna arrays and receive beams to differentiate signals. By utilizing the spatial domain as an additional dimension for signal separation, the system can distinguish between multiple transmitters without requiring additional frequency or time resources, thus maintaining spectral efficiency.
2Reliability
If orthogonal signaling is used in terrestrial wireless communication systems, then signal differentiation and decoder complexity are improved, but multipath interference increases
Solution Approach 1:
The patent converts multipath interference into a beneficial feature by using receive beamforming to selectively enhance desired signal paths while suppressing interfering paths. The system identifies and reinforces paths carrying valid data symbols, transforming what was previously harmful interference into useful signal energy for improved differentiation.
Solution Approach 2:
The patent applies local quality by assigning different characteristics to different receive beams. Each beam is optimized for specific spatial directions and path lengths, allowing the system to selectively process signals based on their origin. This localized processing enables effective signal differentiation while mitigating multipath interference from unwanted directions.
3Productivity
If multiple transmitters transmit orthogonally modulated signals with frequencies within the same range, then frequency spectrum utilization is improved, but signal differentiation deteriorates
Solution Approach 1:
The patent moves signal differentiation from the frequency domain to the spatial domain using multiple antenna arrays and receive beams. By exploiting spatial separation between transmitters, the system can differentiate signals even when they occupy the same frequency range, thus maintaining high frequency spectrum utilization while achieving reliable signal differentiation.
Solution Approach 2:
The patent segments the frequency spectrum utilization across multiple spatial channels created by different receive beams. Each beam can independently process signals from different spatial directions, allowing multiple transmitters to share the same frequency spectrum without interference, thereby maintaining both high spectral efficiency and reliable signal differentiation.
Data Source
AI summary
Techniques for differentiating orthogonally modulated symbols from different transmitters using one or more antenna arrays are described. According to some techniques, symbols received at one or more antenna arrays are grouped together by matching respective sets of receive beams for each symbol. In this manner, symbols received from a first transmitter at a first location can be differentiated from symbols received from a second transmitter at a second location, and both sets of symbols can be successfully decoded. When the symbols are received using frequency hopping, the receive beams for each symbol can be sorted according to path length, which improves performance, and also enables precise location of the transmitter(s).