Satellite Navigation Message Encoding for Interchangeable Page Retrieval
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Solution Overview
Problem
Current satellite navigation systems face challenges in optimally retrieving satellite navigation messages composed of several pages from multiple sources at an affordable decoding cost, especially in degraded reception conditions such as urban canyons and under tree canopies, due to high error rates and limited signal availability.
Innovation Solution
The method involves dividing the satellite navigation message into pages, encoding each symbol position separately using Reed-Solomon codes, and allocating these encoded pages to multiple satellites for transmission, allowing for interchangeable decoding at the user receiver, even with partial page reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If long messages are transmitted using conventional encoding schemes, then message length can be increased, but decoding complexity and overhead increase significantly
Solution Approach 1:
The patent divides a long navigation message into multiple shorter pages, each independently encoded with Reed-Solomon codes. This segmentation allows the receiver to decode shorter blocks separately rather than processing one extremely long message, significantly reducing decoding complexity while maintaining the ability to transmit large amounts of data across multiple pages
Solution Approach 2:
The patent introduces parallel encoding across multiple pages with systematic arrangement of data and parity bits. By organizing the code structure in a multi-dimensional layout where pages can be received in any order and combined flexibly, the system achieves efficient decoding through parallel processing rather than sequential processing of a single long message
2Reliability
If messages are split into multiple chunks for transmission, then reception robustness improves, but loss of information increases when one chunk is not received
Solution Approach 1:
The patent merges multiple encoded pages into a unified code structure where data and parity bits are systematically distributed across all pages. This allows the receiver to combine any sufficient number of received pages to reconstruct the complete message, ensuring that no single page is critical and minimizing information loss even when some pages are lost during transmission
Solution Approach 2:
The patent employs Reed-Solomon codes with specific code rates and lengths that optimize the balance between redundancy and information density. By carefully selecting code parameters, the system achieves high reception robustness while minimizing the overhead required to protect against data loss, ensuring efficient use of the limited bandwidth
3Reliability
If high parity/data ratios are used for long messages from multiple satellites, then error correction capability improves, but transmission efficiency decreases
Solution Approach 1:
By segmenting the long message into multiple pages with moderate redundancy ratios, the patent avoids the need for extremely high overall parity/data ratios. Each page carries a manageable amount of redundancy, and the systematic arrangement allows efficient combination of multiple pages, achieving strong error correction capability without excessive overhead that would severely impact transmission efficiency
Data Source
AI summary
Described herein is a method for improving the reception of a satellite navigation message divided in several pages and transmitted by one or several satellites. A satellite navigation message M of k pages is encoded inn pages, and any k retrieved pages from any satellite enables decoding of the original satellite navigation message M. An implementation of the method uses parallel block encoding for a binary erasure channel with high parity and zero overhead, where symbols at a fixed position of all pages are encoded in parallel into shorter codes. This method achieves full page interchangeability in the message transmission, optimizes message reception and reduces decoding cost.