Dual-Channel Satellite Broadcast for Mobile Blockage Mitigation
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Solution Overview
Problem
Satellite communications in Ka or Ku frequency bands face significant blockage issues, particularly for mobile terminals, where existing blockage protection systems are not effective due to the limited range of terrestrial augmentation using these frequencies.
Innovation Solution
A method and system that duplicate and encode communication bits, transmitting one stream via satellite and another via terrestrial channels, combining them using computed Log Likelihood Ratios (LLR) to enhance signal reliability and reduce blockage interference, employing interleaving, modulation, and error correction mechanisms like LDPC encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If Ka-band or Ku-band frequencies are used for satellite transmissions to increase data transmission rates and enable global coverage, then transmission speed and coverage are improved, but blockage interference increases due to limited range of terrestrial augmentation
Solution Approach 1:
The patent combines satellite channel transmissions with terrestrial channel transmissions into a unified communication system. The mobile terminal receives signals from both satellite and terrestrial base stations, processes them through a combined decoder that integrates Log-Likelihood Ratios (LLRs) from both channels, and reconstructs the original data stream. This merging allows the system to leverage the high-speed global coverage of satellite Ka/Ku-band transmissions while compensating for blockage interference through terrestrial signal paths, thereby resolving the contradiction between transmission speed and blockage susceptibility
2Reliability
If very long interleaving and long period storage are used to overcome blockage periods, then blockage protection is improved, but system complexity and cost increase
Solution Approach 1:
The patent introduces a terrestrial communication channel as an intermediary to bridge the mobile terminal and the satellite communication system. Instead of relying solely on complex interleaving and long-period storage within the satellite system, the terrestrial base station acts as a mediator that provides alternative signal paths during blockage events. The mobile terminal's receiver combines signals from both satellite and terrestrial channels, using the terrestrial channel as a backup pathway that simplifies the overall blockage protection mechanism while maintaining high reliability
3Reliability
If terrestrial augmentation is deployed to reduce blockage, then blockage protection is improved, but the range and effectiveness are limited when using Ka-band frequencies
Solution Approach 1:
The patent adds a spatial dimension to the communication architecture by integrating both satellite (space-based) and terrestrial (ground-based) transmission paths. This dual-dimensional approach allows the system to overcome the limited coverage range of terrestrial Ka-band augmentation alone. The mobile terminal can switch between or combine signals from the satellite channel (providing wide-area coverage) and the terrestrial channel (providing local coverage), thereby extending the effective coverage range while maintaining blockage protection
Data Source
AI summary
A method and a system are provided for use in a satellite communications network in which broadcasting services are provided to a mobile terminal. The method comprises: duplicating bits comprised in communications which the satellite is about to broadcast, thereby forming a first stream of bits and a second stream of bits; conveying the first stream of bits in an encoded form along a satellite channel whereas the second stream of bits is conveyed in an encoded form along a terrestrial channel; and combining bits conveyed along the satellite channel with bits conveyed along the terrestrial channel in order to obtain a combined stream of bits.