Systematic Polar Codes for Rateless Wireless Retransmissions
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Solution Overview
Problem
Wireless communication systems using rateless polar codes face challenges in efficiently retransmitting failed bits due to the lack of defined feedback mechanisms and increased latency and bandwidth requirements for indicating decoding failures in multiple-access systems like 4G and 5G networks.
Innovation Solution
Implementing systematic polar codes that allow for retransmission of encoder input bits based on their likelihood of error, independent of the original polar code, to facilitate efficient retransmissions and improve decoding capacity in wireless communication systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rateless polar codes are used for encoding, then decoding capacity is improved, but retransmission efficiency deteriorates due to lack of defined feedback mechanisms
Solution Approach 1:
The patent implements a feedback mechanism where the receiving device sends feedback information to the transmitting device indicating which bits were decoded successfully and which failed. This feedback enables the transmitting device to perform targeted retransmissions of only the failed bits, resolving the contradiction by providing the necessary feedback structure for rateless polar codes to achieve both high decoding capacity and efficient retransmission.
Solution Approach 2:
The patent segments the retransmission process by identifying and separately handling failed bits from successfully decoded bits. Instead of retransmitting entire codewords, the system segments retransmission to only include the specific bits that failed decoding, improving retransmission efficiency while maintaining the benefits of rateless polar codes.
2Device complexity
If traditional retransmission methods are used, then feedback mechanisms are simple, but latency and bandwidth overhead increase
Solution Approach 1:
The patent extracts only the essential feedback information needed for retransmission - specifically, identification of failed bits - rather than transmitting complete codeword status or using complex acknowledgment schemes. This extraction approach reduces feedback overhead and latency while maintaining effectiveness.
Solution Approach 2:
The patent uses partial action by retransmitting only the subset of bits that failed decoding rather than performing full retransmission of entire codewords. This partial retransmission approach reduces bandwidth overhead and latency while maintaining reliability.
3Reliability
If complete codeword retransmission is performed, then decoding reliability is maintained, but bandwidth overhead increases
Solution Approach 1:
The patent extracts and identifies only the specific bits that failed decoding using feedback information, then retransmits only this extracted subset rather than the complete codeword. This significantly reduces bandwidth overhead while maintaining decoding reliability through targeted retransmission of only necessary bits.
Solution Approach 2:
The patent changes the parameter of retransmission from fixed (complete codeword) to variable (only failed bits based on feedback). This dynamic parameter adjustment optimizes bandwidth usage by adapting the retransmission size to the actual number of failed bits, maintaining reliability while reducing overhead.
Data Source
AI summary
Methods, systems, devices, and apparatuses that support rateless polar codes are used to provide for retransmissions in cases that a codeword is encoded using a rateless polar code. For example, a first wireless device may transmit, to a second wireless device, a codeword corresponding to a set of information bits encoded using a rateless polar code. In cases where the first wireless device identifies that the second wireless device failed to decode one or more of the information bits, the first wireless device may select a subset of the encoder input bits for retransmission based on an order of a likelihood of error associated with a set of bit-channels used for encoding the set of information bits using the polar code. The number of retransmitted encoder input bits may be based further on a gap to capacity calculated by the first wireless device and/or the second wireless device.