2D Joint Coding for Broadcast Multicast Groupcast Transmission
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Solution Overview
Problem
Conventional retransmission schemes in broadcast, multicast, and groupcast wireless communications are inefficient, leading to latency and high overhead, as they often require retransmitting entire transport blocks or code block groups in a highly redundant manner.
Innovation Solution
The implementation of PHY layer network coding based on 2D joint coding, which involves transmitting two or more information code blocks and generating cross-CB check blocks to be used for decoding, even if receivers have different erroneous code blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional retransmission schemes are used in broadcast, multicast, or groupcast transmissions, then reliability is maintained through retransmitting erroneous data, but transmission overhead and latency increase significantly due to retransmitting entire transport blocks or code block groups in a highly redundant manner
Solution Approach 1:
The patent segments the transport block into multiple code blocks and further divides them into code block groups. Instead of retransmitting entire transport blocks or large code block groups, the system identifies and retransmits only the specific erroneous code blocks or even individual erroneous bits within code blocks. This granular segmentation reduces redundancy and transmission overhead while maintaining decoding reliability.
Solution Approach 2:
The patent extracts and identifies only the erroneous portions of transmitted data through feedback mechanisms. Rather than retransmitting complete transport blocks, the system extracts specific erroneous code blocks or bit positions and retransmits only those portions. This extraction approach eliminates unnecessary redundancy and reduces transmission overhead significantly.
2Reliability
If conventional retransmission schemes retransmit entire transport blocks or code block groups, then decoding reliability is improved, but transmission time and latency increase due to the redundant retransmission process
Solution Approach 1:
The patent implements fine-grained segmentation of transport blocks into code blocks and code block groups, enabling identification of specific erroneous segments. This segmentation allows the system to retransmit only the necessary portions rather than entire transport blocks, significantly reducing retransmission time and latency while maintaining decoding reliability.
Solution Approach 2:
The patent applies partial action by retransmitting only the minimum necessary data portions (specific erroneous code blocks or bits) rather than complete transport blocks. This partial retransmission approach reduces transmission time and latency while providing sufficient information for successful decoding at the receiver.
3Loss of substance
If erasure outer code based retransmission is used, then transmission overhead is reduced by discarding undecoded code blocks, but performance deteriorates because no soft information is retained for joint decoding
Solution Approach 1:
The patent changes the parameter of information retention by preserving soft information (log-likelihood ratios) from unsuccessful decoding attempts instead of discarding undecoded code blocks. This parameter change allows the system to maintain decoding performance while reducing transmission overhead, as the retained soft information can be combined with retransmitted data for joint decoding.
Solution Approach 2:
The patent implements feedback mechanisms where receivers provide information about decoding status and erroneous portions to transmitters. This feedback enables the transmitter to send targeted retransmissions while the receiver uses feedback from previous decoding attempts to improve subsequent decoding, maintaining performance without excessive overhead.
Data Source
AI summary
Methods and systems for two-dimensional (2D) coding are described for broadcast, multicast or groupcast applications. Two or more information code blocks (CBs) are transmitted to a plurality of intended receiving nodes. One or more cross-CB check blocks are generated, each cross-CB check block being generated based on a set of cross-CB bits, the set of cross-CB bits including at least one bit selected from each of at least two of the information CBs. At least one cross-CB check block is transmitted to at least one of the intended receiving nodes.