Fountain Code Relaying with Degree-Constrained Packet Combining
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Solution Overview
Problem
In vehicular communication systems, particularly in Dedicated Short-Range Communications (DSRC), there is a challenge in efficiently relaying fountain codes due to high decoding complexity, which limits their applicability in large-scale content delivery amidst dynamic topology and unpredictable erasures.
Innovation Solution
A low-complexity network coding scheme, known as distributed-fountain network code (DFNC), is implemented, where intermediate vehicles perform degree reduction and degree-constrained combining to approximate the fountain code, utilizing low-complexity belief propagation decoding at destinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fountain code is used for content delivery in vehicular networks, then reliability is improved, but decoding complexity increases
Solution Approach 1:
The patent segments the fountain code relaying process into two distinct phases: degree reduction phase (where intermediate nodes reduce packet degrees to minimum values) and degree-constrained combining phase (where nodes combine packets with controlled degree constraints). This segmentation simplifies the decoding process at intermediate nodes while preserving the reliability benefits of fountain codes.
Solution Approach 2:
The patent changes the degree parameter of packets during relaying by reducing degrees to minimum values and constraining combination degrees. This parameter transformation allows intermediate nodes to operate with simplified logic while maintaining the overall fountain code structure and reliability at destination nodes.
2Reliability
If traditional fountain code relaying is implemented, then file-broadcasting reliability is improved, but computational complexity increases
Solution Approach 1:
The relaying process is divided into degree reduction operations (low computational requirement) and degree-constrained combining operations (controlled computational complexity). This segmentation ensures that computational complexity remains manageable at intermediate nodes while file-broadcasting reliability is maintained through the fountain code structure.
Solution Approach 2:
By transforming packet degrees to minimum values and imposing degree constraints on combining operations, the patent reduces computational complexity at intermediate nodes. The computational burden is shifted to degree management rather than complex decoding operations, while reliability is preserved through the fountain code's inherent properties.
3Device complexity
If degree reduction and degree-constrained combining are applied, then device complexity is reduced, but packet processing overhead increases
Solution Approach 1:
The patent performs degree reduction as a preliminary action before packet combining. By reducing degrees to minimum values in advance, intermediate nodes simplify subsequent combining operations and avoid the need for complex real-time degree management during packet processing, thereby reducing overall processing overhead.
Solution Approach 2:
The degree parameter is transformed to minimum values in advance (preliminary action), which simplifies subsequent packet processing operations. This parameter change reduces the computational burden during actual packet transmission and combining, offsetting the initial degree reduction overhead with simplified downstream processing.
Data Source
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AI summary
A method, an apparatus, and a computer program product for relaying a packet are provided. The apparatus receives at least one packet and reduces a degree of the at least one packet. The apparatus further processes the at least one packet based on the reduced degree, generates a combined packet by combining the at least one processed packet with at least one other processed packet based on the reduced degree and a weight of each of the processed packets, and transmits the combined packet.