OFDM Symbol-Aligned Code Blocks for Faster ACK/NACK Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing LTE code block segmentation method does not align code blocks with orthogonal frequency division multiplexing (OFDM) symbols, leading to partial transmission of code blocks across two OFDM symbols, which delays acknowledgments (ACKs)/negative acknowledgments (NACKs) and hinders successive interference cancellation (SIC) by preventing interference subtraction until the entire code block is received.
Innovation Solution
Aligning code blocks with OFDM symbol borders, either by perfect alignment or grouping OFDM symbols to maintain a suitable trade-off between alignment and code block size, allowing for efficient pipelined processing and earlier ACK/NACK transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If code blocks are segmented without alignment to OFDM symbols (LTE type CBS), then code block size can be maintained larger, but code blocks are partially transmitted across two OFDM symbols causing delayed ACK/NACK and hindering SIC
Solution Approach 1:
The patent segments the transmission timeline into groups of OFDM symbols and further segments code blocks to align with these groups. This dual segmentation allows code blocks to be contained within specific OFDM symbol groups, enabling independent processing of each group and eliminating the need to wait for complete code block reception across symbol boundaries.
Solution Approach 2:
The patent introduces a grouping dimension by organizing OFDM symbols into groups before mapping code blocks. This adds a temporal grouping layer that allows code blocks to be aligned with group boundaries rather than individual symbol boundaries, resolving the conflict between maintaining large code block sizes and enabling timely ACK/NACK feedback.
2Quantity of substance
If code blocks are segmented without alignment to OFDM symbols, then code block size can be maintained larger, but pipelined processing of each OFDM symbol becomes more difficult
Solution Approach 1:
By segmenting both the OFDM symbols into groups and code blocks accordingly, the patent creates independent processing units that can be handled in a pipelined manner. Each group of OFDM symbols contains complete code blocks, allowing receivers to process each group independently through the pipeline without waiting for other groups, thus simplifying the processing architecture.
Solution Approach 2:
The patent performs preliminary grouping of OFDM symbols and alignment of code blocks to group boundaries before transmission. This preliminary organization ensures that code blocks are already positioned to be contained within specific groups, enabling the receiver to immediately begin pipelined processing without complex real-time alignment operations.
3Loss of time
If perfect alignment of code blocks with OFDM symbols is performed, then ACK/NACK latency is reduced and SIC is enabled, but code block size becomes significantly shorter
Solution Approach 1:
The patent resolves this contradiction by moving from aligning code blocks with individual OFDM symbols to aligning them with groups of OFDM symbols. This dimensional change allows code blocks to span multiple symbols within a group while still maintaining alignment with the group boundary, thus preserving larger code block sizes while enabling timely processing at group boundaries.
Solution Approach 2:
The patent makes the alignment granularity dynamic by allowing the receiver to configure the number of OFDM symbols per group based on traffic conditions and code block size requirements. This dynamic grouping enables flexible adjustment between larger groups (for larger code blocks) and smaller groups (for lower latency), resolving the fixed trade-off between code block size and latency.
Data Source
AI summary
According to some embodiments, a method in a wireless transmitter of aligning code blocks with modulation symbols comprises: receiving a block of information bits for wireless transmission in a plurality of modulation symbols; partitioning the plurality of modulation symbols into groups of one or more modulation symbols, wherein the modulation symbols in a group are contiguous in time; and assigning each of the information bits to one of the groups. For each of the groups the method further comprises: segmenting the assigned information bits in the group into one or more code blocks; encoding each code block into coded bits; and assigning the coded bits of the one or more code blocks to the group of modulation symbols the information bits are assigned to. The method further comprises transmitting the groups of modulation symbols to a wireless receiver.