Scalable Signal FEC Using Inter-Layer Redundancy Dependencies
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Solution Overview
Problem
Existing forward error correction (FEC) schemes for scalable media signals do not effectively utilize the inter-relationship among different layers, leading to inadequate protection and increased error probability in decoding, especially in scenarios where lower layers are affected, resulting in unsuccessful decoding of higher enhancement layers due to missing references.
Innovation Solution
The proposed solution involves a layered FEC approach where redundancy information for higher-level portions is dependent not only on disjoint but also overlapping lower-level portions, enhancing the chances of successful error correction by leveraging inter-layer dependencies, thereby increasing the probability of errorless reconstruction without increasing the overall redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If independent FEC protection is used for each enhancement layer, then the decoding complexity is reduced and each layer can be protected individually, but the overall error protection effectiveness deteriorates because lower layer losses cannot be compensated by higher layer redundancy
Solution Approach 1:
The patent merges the FEC protection mechanisms across multiple enhancement layers by generating redundancy symbols that depend on source symbols from multiple layers. Specifically, redundancy symbols for higher layers are generated using source symbols from both the higher layer and lower layers, creating an interconnected protection system where error correction in one layer can benefit from redundancy generated for other layers.
Solution Approach 2:
The patent applies preliminary action by generating redundancy symbols that anticipate potential losses in lower layers. The redundancy symbols are pre-generated with dependencies on lower layer source symbols before transmission, so that when lower layer losses occur, the higher layer redundancy symbols can compensate for these losses during decoding.
2Reliability
If stronger FEC protection with more redundancy symbols is applied to lower layers, then the protection probability for lower layers increases, but the overall redundancy overhead increases and the inter-layer dependency relationships are not utilized
Solution Approach 1:
The patent makes the redundancy symbols universal by designing them to serve multiple functions simultaneously. Redundancy symbols generated for higher layers not only protect the higher layer data but also provide protection for lower layer data. This multi-functional redundancy reduces the total amount of redundancy needed compared to independent protection schemes.
Solution Approach 2:
The patent changes the dependency parameters of redundancy symbols from layer-independent to layer-dependent. By modifying how redundancy symbols are generated (changing the parameter of dependency relationships), the system achieves better protection efficiency without increasing redundancy quantity.
3Ease of manufacture
If redundancy symbols for higher layers depend only on disjoint source symbols, then the redundancy generation is simplified, but the error correction capability deteriorates because overlapping lower layer portions are not utilized
Solution Approach 1:
The patent creates composite redundancy symbols that combine dependencies on multiple source symbols from different layers. Instead of using simple single-layer source symbols, the redundancy symbols are generated using composite dependencies on source symbols from both lower and higher layers, enhancing error correction capability while maintaining reasonable generation complexity.
Data Source
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AI summary
A scalable information signal is protected in a more efficient and/or safe way by adopting the interrelationship among the plurality of portions of different levels within the information signal in FEC protecting the information signal. In particular, portions of the information signal representing the information content at a higher level should have associated therewith redundancy information which is dependent not only on that part of this portion being disjoint to a respective overlapping lower level portion. Rather, redundancy information should also be dependent on the latter part so as to increase the chances of success of forward error correcting an error within the lower level portion at the reception side.