Symbol Vector Mapping for Chase Combining HARQ
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Solution Overview
Problem
Chase Combining HARQ techniques in OFDM systems often fail to generate an acceptable data packet due to interference or noise corrupting the same bits during retransmissions, especially when subcarrier quality changes over time.
Innovation Solution
Implementing time-varying symbol vector mapping, where symbols are remapped to different subcarriers and antennas during retransmissions, allowing the system to exploit changing subcarrier qualities and improve reception probability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Chase Combining HARQ is used to improve reliability through retransmissions, then the probability of successful data packet assembly increases, but the same interference or noise corrupts the same bits during retransmissions causing the technique to fail
Solution Approach 1:
The patent applies dynamics by making the subcarrier mapping time-varying and adaptive. Instead of using a fixed mapping pattern for retransmissions, the system dynamically changes the subcarrier assignment based on current channel conditions. This allows the receiver to combine transmissions that experience different interference patterns, thereby improving reliability while avoiding repeated corruption from static mapping vulnerabilities.
Solution Approach 2:
The patent changes the mapping parameter (subcarrier assignment) between initial transmission and retransmissions. By varying the subcarrier mapping pattern, the system ensures that retransmitted symbols are mapped to different subcarriers than the original transmission, reducing the probability that the same bits will be corrupted by identical interference or noise patterns across retransmissions.
2Device complexity
If symbols are mapped to fixed subcarriers for simple processing, then computational complexity is reduced, but subcarrier quality changes over time reducing reception probability
Solution Approach 1:
The system implements dynamic subcarrier mapping that adapts to changing channel conditions without requiring complex computational processing. The mapping pattern changes between transmissions based on subcarrier quality variations, allowing the system to exploit favorable subcarrier conditions while maintaining relatively simple receiver processing through structured mapping patterns.
3Ease of operation
If subcarrier mapping remains constant for ease of operation, then system operation is simplified, but the system cannot exploit changing subcarrier qualities
Solution Approach 1:
The patent introduces dynamic adaptation in subcarrier mapping while maintaining operational simplicity through structured approaches. The system automatically adjusts mapping patterns to exploit favorable subcarrier conditions, improving data transmission effectiveness without requiring complex manual intervention or processing, thus balancing ease of operation with enhanced productivity.
Data Source
AI summary
A method includes mapping, based on a first antenna mapping, a plurality of symbols to a plurality of antennas for transmitting a first data unit to a receiver, mapping, based on a first subcarrier mapping, the plurality of symbols to a plurality of subcarriers for transmitting the first data unit, and determining whether the receiver has successfully received the first data unit. The method also includes, in response to determining that the receiver has not successfully received the first data unit, (i) mapping, based on a second antenna mapping, the plurality of symbols to the plurality of antennas for transmitting a second data unit to the receiver, (ii) mapping, based on a different, second subcarrier mapping, the plurality of symbols to the plurality of subcarriers for transmitting the second data unit, and (iii) causing the second subcarrier mapping to be communicated to the receiver.