Hybrid-ARQ Code Book Using Linear Constellation Precoding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hybrid-ARQ schemes, such as CC-ARQ and CoRe-ARQ, face limitations in resilience and throughput due to channel noise, particularly in wireless communication systems, where retransmissions are susceptible to noise and decoding complexity is high.
Innovation Solution
A new hybrid-ARQ scheme is introduced that constructs a code book of vectors using linear constellation precoding, where a distinct vector is selected for every subset of information bits, and elements are transmitted one by one based on ACK/NACK feedback, allowing for improved error correction and throughput without increasing decoding complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ARQ schemes are used with retransmission, then link reliability is improved, but throughput deteriorates as channel noise increases
Solution Approach 1:
The patent combines ARQ (Automatic Repeat Request) with FEC (Forward Error Correction) to create a hybrid scheme. The FEC encoder adds redundancy bits that enable error correction without requiring retransmission, while ARQ provides fallback retransmission capability. This merging allows the system to correct errors proactively (improving throughput) while maintaining reliability through retransmission when necessary.
Solution Approach 2:
The patent applies preliminary error correction by adding FEC redundancy bits to packets before transmission. This preliminary action enables the receiver to correct certain errors autonomously without waiting for retransmission, thereby improving throughput while maintaining link reliability. The system performs error correction in advance rather than reacting to errors after transmission.
2Reliability
If Type I hybrid-ARQ with FEC is used, then error correction capability is improved, but transmission overhead increases
Solution Approach 1:
The patent dynamically adjusts the FEC code rate parameter based on channel conditions and retransmission history. The system can vary the number of redundancy bits added to packets, allowing optimization between error correction capability and transmission overhead. When channel conditions are good, fewer redundancy bits are added; when conditions deteriorate or retransmissions occur, more redundancy is provided.
Solution Approach 2:
The patent applies partial FEC correction by adding a limited number of redundancy bits that can correct a subset of errors, rather than providing excessive correction for all possible error scenarios. This partial action reduces transmission overhead while still improving error correction capability for the most common error patterns, balancing reliability improvement with overhead constraints.
3Reliability
If Type II hybrid-ARQ with code combining is used, then performance is improved, but decoding complexity increases
Solution Approach 1:
The patent segments the decoding process into distinct stages: initial FEC decoding attempt, error detection, and conditional retransmission handling. By dividing the complex Type II hybrid-ARQ decoding into manageable segments, the system improves performance through comprehensive error correction while keeping each decoding stage's complexity manageable. The segmentation allows the receiver to process packets in discrete steps rather than handling all complexity simultaneously.
Solution Approach 2:
The patent extracts and handles the most complex decoding operations selectively rather than applying full Type II hybrid-ARQ decoding to all packets. The system extracts only the necessary error correction operations based on packet status (initial transmission vs. retransmission) and error patterns, reducing overall decoding complexity while maintaining performance improvements where they are most needed.
Data Source
AI summary
Apparatuses, computer readable media, and methods are provided for enhancing hybrid automatic repeat request (ARQ) performance. In an example method, a communication device transmits a first element of a vector, where the vector is selected using the information bits to be transmitted as an index in a code book. In some embodiments, this code book is constructed using Linear Constellation Precoding (LCP). If a NACK is received, the communication device transmits a second element of the vector. The process of transmitting elements of the vector continues until an ACK is received or the maximum number of transmission attempts is reached. If an ACK is received, the communication device transmits a first element of another vector of the code book that encodes a second set of information bits. This procedure may continue until all information bits have been transmitted successfully.