Network Coding for LTE Data Transmission Feedback Overhead
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Solution Overview
Problem
In LTE systems, data transmission latency is increased due to the two-layer retransmission mechanism (HARQ and ARQ), and existing solutions that use outer encoding to reduce latency result in high feedback overheads, especially in poor channel conditions.
Innovation Solution
The method involves determining a specified quantity of code blocks (CBs) to be sent over the air interface using network coding, where the difference between correctly received CBs and required CBs is used to adjust the quantity, reducing retransmission overheads and feedback load by dynamically adjusting the number of CBs based on feedback thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If outer encoding is used to generate redundant CBs for error correction, then data transmission reliability is improved, but feedback overhead is significantly increased when channel quality is poor
Solution Approach 1:
The patent implements dynamic feedback mechanisms where the receiver adaptively adjusts feedback behavior based on channel conditions. When channel quality is good, detailed CB-level feedback is provided. When channel quality deteriorates, the system transitions to more compact feedback modes, dynamically balancing reliability requirements against feedback overhead constraints.
Solution Approach 2:
The system changes feedback parameters based on channel quality indicators. The feedback granularity, feedback frequency, and redundancy level are adjusted as parameters according to channel conditions, allowing the system to maintain reliability while controlling feedback overhead in poor channel scenarios.
2Loss of substance
If the receiver feeds back the quantity of incorrectly received CBs to enable CB granularity-based retransmission, then air interface resource overheads are reduced, but feedback overheads are increased
Solution Approach 1:
Instead of providing complete CB-level feedback for all incorrectly received blocks, the system applies partial feedback action. When channel conditions are poor, the receiver provides selective feedback on a subset of critical CBs or uses compressed feedback representations, achieving acceptable retransmission efficiency while limiting feedback overhead growth.
Solution Approach 2:
The patent introduces an intermediary feedback mechanism that translates detailed CB-level error information into compressed representations. This intermediary layer processes the feedback information, converting granular CB error data into more compact forms that reduce uplink feedback overhead while still enabling effective retransmission at the transmitter.
3Reliability
If the transmitter retransmits the entire TB block upon receiving NACK feedback, then data transmission reliability is ensured, but data transmission latency is increased
Solution Approach 1:
The patent segments the transport block into individual code blocks that can be independently identified and retransmitted. Instead of treating the entire TB as a single unit, the system divides it into smaller CB units, enabling selective retransmission of only those CBs that failed decoding, thereby reducing latency while maintaining reliability.
Solution Approach 2:
The system performs preliminary segmentation and numbering of code blocks before transmission. Each CB is pre-marked with identification information, enabling the receiver to quickly identify which specific CBs failed and allowing the transmitter to prepare targeted retransmissions in advance, reducing the time required for error correction.
Data Source
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AI summary
A data transmission method and apparatus and a data processing method and apparatus are provided. The method includes: determining, by a first device, first information, where the first information is used to indicate a quantity of code blocks CBs to be sent over an air interface; generating, by the first device, the CB after performing network coding on a target transport block TB, and sending the CB to a second device based on the first information; receiving, by the first device, second information sent by the second device, where the second information is used to adjust the quantity, indicated by the first information, of CBs to be sent over the air interface; receiving, by a sending device, a target protocol data unit RLC PDU, and performing network coding on the target RLC PDU to obtain at least one network code block; and generating, by the sending device, the target TB based on the at least one network code block.