Block Retransmission Control Using Inner-Outer Code Error Limits
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Solution Overview
Problem
In wireless communication systems using both inner and outer codes for error correcting, retransmission schemes often lead to inefficient use of resources due to unnecessary retransmissions, as errors corrected by the outer code are still retransmitted along with those that can be corrected by the inner code.
Innovation Solution
A retransmission ordering method that determines whether to retransmit based on the likelihood information of inner-code errors, inhibiting retransmissions if the number of errors is within the outer code's correction limit and only retransmitting when errors exceed this limit, thereby optimizing the use of wireless communication resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retransmission is performed for all blocks with inner-code errors, then error correction reliability is improved, but transmission efficiency deteriorates due to unnecessary retransmissions when outer code can correct the errors
Solution Approach 1:
The invention changes the retransmission decision parameter from a simple binary decision (retransmit or not) to a probabilistic decision based on likelihood information. By quantifying the error probability of each block and comparing it against a threshold, the system dynamically adjusts retransmission behavior based on actual channel conditions and error severity, thereby avoiding unnecessary retransmissions while maintaining reliability.
Solution Approach 2:
The invention introduces feedback mechanisms where the receiver evaluates the likelihood of errors in received blocks and provides this information back to the transmitter. The transmitter uses this feedback to make informed retransmission decisions, only retransmitting blocks that truly need correction. This feedback loop enables the system to adapt to varying channel conditions and optimize the balance between reliability and transmission efficiency.
2Productivity
If likelihood information is used to determine retransmission necessity, then transmission efficiency is improved, but system complexity increases due to additional processing requirements
Solution Approach 1:
The invention segments the error correction process by treating each block independently with its own likelihood evaluation. Instead of processing the entire frame as a single unit, the system divides it into manageable blocks, evaluates each block's error probability separately, and makes independent retransmission decisions for each. This segmentation reduces the computational complexity of likelihood calculation while maintaining overall system efficiency.
Data Source
AI summary
A wireless communication system wherein frame data is encoded with an outer code and then divided into predetermined number of blocks which are encoded with an inner code into transmission data. In a receiver, a decoder decodes the received transmission data in accordance with the inner code, a retransmission order determining unit determines whether to perform a retransmission order in units of blocks based on the likelihood information (decoded soft-decision value). At this time, the retransmission order determining unit inhibits the retransmission order for the block if the number of inner-code errors in a frame consisting of predetermined number of blocks stays within a limit of what the outer code can correct at a decoder and determines that a retransmission is necessary if the number of inner-code errors in the frame exceeds the limit.