LTE Code Block Interleaving for Time-Domain Burst Error Robustness
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Solution Overview
Problem
Current LTE systems lack a detailed interleaving operation, which compromises the robustness of data transmission against burst errors in wireless channels, leading to potential loss of code blocks and inefficient use of wireless resources due to HARQ retransmissions.
Innovation Solution
The implementation of a time-first-mapping method for interleaving, where code blocks are mapped to time-frequency resources by sequentially changing time-domain indexes with fixed frequency-domain indexes, and an interleaving operation that considers the modulation scheme to prevent symbols from different code blocks from constituting a single modulation symbol, ensuring robustness against time-domain burst errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no interleaving operation is performed, then the system complexity is low, but the robustness against burst errors deteriorates
Solution Approach 1:
The patent segments code blocks into multiple groups and distributes them across different time-frequency resources through interleaving. This segmentation allows the system to handle burst errors more effectively by ensuring that errors affecting one group do not completely destroy a single code block, thus improving robustness without requiring complex interleaving mechanisms.
Solution Approach 2:
The patent introduces time-domain interleaving as an additional dimension for resource allocation. By mapping code block groups to different time slots and SC-FDMA symbols, the system disperses burst errors across multiple dimensions (frequency and time), enhancing error resilience while maintaining manageable system complexity through structured mapping rules.
2Reliability
If code blocks are transmitted without considering modulation scheme in interleaving, then the interleaving operation is simpler, but symbols from different code blocks may constitute a single modulation symbol causing errors
Solution Approach 1:
The patent applies local quality by making the interleaving operation aware of the modulation scheme. Different modulation schemes (QPSK, 16QAM, 64QAM) have different symbol rates and error characteristics. The interleaver adapts its mapping strategy locally according to the specific modulation scheme being used, ensuring that symbols from the same code block are properly grouped for modulation, thereby improving reception reliability while maintaining reasonable complexity through scheme-specific optimization.
3Productivity
If code blocks are transmitted in poor channel conditions without interleaving, then the transmission is faster, but complete code block loss occurs more frequently
Solution Approach 1:
The patent performs preliminary interleaving of code blocks before transmission, distributing them across multiple time-frequency resources in advance. This preliminary action ensures that when poor channel conditions occur, the impact is spread across multiple code block groups rather than affecting a single code block completely, enabling successful recovery through error correction while maintaining transmission efficiency.
Solution Approach 2:
The interleaving structure acts as a cushion against burst errors by pre-distributing code blocks in a way that provides redundancy protection. When channel conditions deteriorate, the structured distribution ensures that not all bits of a single code block are affected simultaneously, providing a buffer that allows error correction mechanisms to recover the data without requiring retransmission, thus protecting against complete code block loss.
Data Source
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AI summary
An interleaving method to which time-first-mapping is applied for a plurality of channel-coded and rate-matched code blocks considering a modulation scheme in a mobile communication system is provided. The interleaving method includes determining sizes of a horizontal area and a vertical area of an interleaver memory, selecting a defined number of adjacent coded symbols in a same code block according to a modulation scheme, generating modulation groups in a vertical direction, sequentially writing the modulation groups in the horizontal area on a row-by-row basis, and sequentially reading the symbols written in the interleaver memory on a column-by-column basis.