Coherent Swarm Signal Arraying Under Doppler and Phase Mismatch
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Solution Overview
Problem
Existing satellite communication systems face challenges in combining individual signals from small satellites or UAVs in a swarm due to synchronization and coordination complexities, which are burdensome and impractical for space-based arraying, especially when signals are weak and affected by differential Doppler frequencies and random phases.
Innovation Solution
A Destination-Based Arraying (DBA) approach using signal processing at the destination receiver to extract phasing and timing for coherent combining, employing a Swarm Array Coherent Combining (SACC) system that multiplexes and demultiplexes signals with Beacon/Preamble signaling and feedback correlation to track carrier noise, enabling closed-loop phase tracking and coherent summing of signals with phase-offsets less than 10°.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If signals are transmitted from multiple nodes in a swarm, then the data rate and signal power are improved, but the synchronization and coordination complexity increases
Solution Approach 1:
The patent inverts the traditional approach by moving synchronization from the transmitter side to the receiver side. Instead of nodes pre-synchronizing their signals before transmission, the destination receiver performs synchronization and coherent combining after receiving the signals. This inversion eliminates the need for complex transmitter coordination while still achieving coherent arraying benefits.
Solution Approach 2:
The destination receiver acts as an intermediary that performs the complex synchronization and phase alignment operations. Rather than requiring each node to coordinate with others, the receiver mediates the process by extracting timing and phasing information and using it to coherent combine the signals, thereby simplifying the node requirements.
2Device complexity
If nodes are uncoupled from each other, then the node complexity is reduced, but the timing and phase precision requirement increases
Solution Approach 1:
Each node transmits its signal independently without requiring coordination with other nodes. The destination receiver then performs self-contained processing for each signal channel, extracting timing and phasing information individually. This self-service approach at the receiver end compensates for the lack of node coupling, maintaining precision without requiring node-level coordination.
3Productivity
If signals are transmitted at high data rates, then the productivity is improved, but the signal becomes buried in noise
Solution Approach 1:
The patent merges multiple individual signals from different nodes into a single combined signal at the destination receiver. By coherent combining the signals from multiple nodes, the signal power adds constructively while noise remains independent, thereby improving the signal-to-noise ratio and enabling reliable detection of high-rate data that would otherwise be buried in noise on individual channels.
Solution Approach 2:
The system uses Beacon/Preamble signaling that creates a template copy of the expected signal structure. The receiver uses this template to correlate with and extract the actual data signals, enabling reliable detection even when the data signals are buried in noise at high data rates. The preamble acts as a reference copy for synchronization and signal extraction.
4Ease of operation
If signals are transmitted without precise timing coordination, then the ease of operation is improved, but the coherent combining capability deteriorates
Solution Approach 1:
The system performs preliminary actions at the receiver by extracting timing and phasing information from the received signals before coherent combining. The receiver measures the actual timing offsets and phase shifts of each incoming signal and uses this information to properly align the signals for coherent combining, thereby achieving phase coherence without requiring precise timing coordination at transmission.
Data Source
AI summary
Swarm Array Coherent Combining (SACC) system utilizes Destination-Based Arraying of individual signals transmitted from nodes arranged in a swarm, where nodes are not burdened with the precise timing and phasing pre-conditioning. The SACC system achieves this objective via an initial Beacon/Preamble signal structure and format that quickly starts the process of closed-loop tracking of the carrier and captures fine signal timing to align the nodes' signals for the coherent summing, and a feedback/correlation scheme that “extracts” each individual node channel signal from being buried in noise to enable closed-loop carrier tracking of the individual nodes' signals, thereby accounting for the ongoing differential Doppler across nodes that would otherwise preclude coherent combining operations.