Hybrid MIMO Across Multi-Antenna Satellites With Easier Time Sync
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Solution Overview
Problem
Non-terrestrial networks face challenges in maintaining high performance due to the large and variable distance between ground-based base stations and satellites, making accurate time synchronization and multi-antenna processing difficult, which affects data rates and reliability.
Innovation Solution
The implementation of a hybrid MIMO system using multiple satellites with multiple antennas per cell, where each satellite has antennas with different polarization angles, allowing for multi-antenna diversity and MIMO processing to compensate for polarization loss and improve link budget, and the ability to switch between antennas based on signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-antenna processing is implemented in NTNs, then reliability and data rates are improved, but time synchronization between antenna streams becomes difficult to achieve
Solution Approach 1:
The patent segments the multi-antenna system into independent satellite units, each performing local MIMO processing. This segmentation allows each satellite to operate autonomously with its own time reference, eliminating the need for complex inter-satellite time synchronization while maintaining multi-antenna diversity benefits
Solution Approach 2:
The patent introduces an intermediary time synchronization mechanism where a reference satellite provides timing signals to other satellites. This mediator approach simplifies the synchronization complexity by reducing the number of synchronization relationships from N*(N-1)/2 to N-1, making the system manageable
2Reliability
If multiple antenna streams are transmitted via different non-terrestrial platforms, then diversity gain is achieved, but accurate time synchronization becomes even more difficult
Solution Approach 1:
The patent implements preliminary time synchronization calibration before actual data transmission. Each satellite performs time offset measurement and compensation in advance, storing correction values that are applied during normal operation. This preliminary action ensures accurate time alignment across multiple platforms without requiring continuous complex synchronization during data transmission
3Productivity
If hybrid MIMO with multiple satellites is implemented, then link budget and data rates are improved, but feeder link bandwidth consumption increases
Solution Approach 1:
The patent merges multiple satellite signals at the ground station receiver, combining the information from multiple feeder links. By using signal combining techniques such as maximum ratio combining, the system achieves diversity gain and improved data rates while efficiently utilizing the total available feeder link bandwidth, rather than requiring proportional bandwidth increases
Data Source
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AI summary
Method comprising: receiving, by a first antenna, a first signal; receiving, by a second antenna, a second signal; forwarding a feeder signal to a base station, wherein the feeder signal is based on the first signal and the second signal, wherein a polarization angle of the second antenna is different from a polarization angle of the first antenna.