HARQ Symbol Detection via Selective Retransmission and Code Block Segmentation
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Solution Overview
Problem
Current telecommunication standards, such as UMTS and LTE, face inefficiencies in Hybrid Automatic Repeat Request (HARQ) transmissions due to wasted bandwidth in retransmitting successfully received blocks and increased decoding complexity in MIMO channels, which limits detection rates and computational efficiency.
Innovation Solution
A method that requests retransmissions based on error-detecting codes, utilizing information from previous transmissions to improve symbol detection by combining corresponding parts and using a-priori information for channel estimation and noise reduction, potentially incorporating soft bits and previously detected modulation symbols to enhance decoding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all blocks are retransmitted in response to a HARQ retransmission request, then reliable data exchange is achieved, but bandwidth is wasted on retransmitting successfully received blocks
Solution Approach 1:
The transport block is segmented into individually decodable code blocks, each with its own CRC check. This allows the receiving device to identify which specific code blocks were successfully received and which need retransmission, enabling selective retransmission of only the failed blocks rather than retransmitting the entire transport block.
Solution Approach 2:
The receiving device provides feedback information to the transmitting device about the CRC status of each individual code block. This feedback mechanism enables the transmitting device to determine which code blocks require retransmission, allowing for efficient selective retransmission that avoids wasting bandwidth on successfully received blocks.
2Productivity
If spatial multiplexing is used to increase spectral efficiency, then more blocks can be transmitted simultaneously, but decoding complexity at the receiving side increases significantly
Solution Approach 1:
The transport block is divided into multiple independently decodable code blocks. This segmentation allows the receiving device to process and decode individual code blocks separately, reducing the overall decoding complexity compared to decoding the entire transport block as a single unit, especially in MIMO spatial multiplexing scenarios.
Solution Approach 2:
Each code block is equipped with individual CRC checks and can be independently decoded. This local independence allows the receiving device to apply decoding efforts selectively to only those code blocks that failed decoding, rather than reprocessing the entire transport block, thereby reducing computational complexity in retransmission scenarios.
Data Source
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AI summary
A technique of processing an Automatic Repeat Request (ARQ) transmission is disclosed. As to a method aspect of the technique, the method (200) comprises the steps of requesting (210) a retransmission of a transport block; receiving (220) the retransmission of the transport block; and detecting (230) modulation symbols. The retransmission is requested in response to an error-detecting code indicating an error in the transport block as received in at least one previous transmission. The modulation symbols are detected based on at least a part of the received retransmission and information from the at least one previous transmission. At least in some embodiments, a detection rate is thus improved.