Short TTI Transport Block Size Downscaling for Latency Reduction
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Solution Overview
Problem
Existing communication systems face challenges in determining optimal transport block sizes for short Transmission Time Intervals (TTIs), as existing tables are designed for longer TTIs, leading to inefficiencies and increased latency, which affects packet data transmission and error correction.
Innovation Solution
A method to determine a short TTI transport block size by downscaling a long TTI transport block size based on the ratio of symbols in the short and long TTIs, using a compensation factor and accounting for control channel and CRC overhead, allowing reuse of existing tables for short TTI operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a short TTI is used, then latency is reduced and link adaptation speed is improved, but transport block size is reduced leading to less efficient error correction
Solution Approach 1:
The patent changes the parameter of transport block size by introducing a scaling factor that adjusts the long TTI transport block size to fit short TTI duration. This allows the system to maintain optimized error correction codes while adapting to shorter transmission times, resolving the contradiction between reduced latency and maintained error correction efficiency.
2Reliability
If a long TTI is used, then error correction efficiency is improved, but latency increases and link adaptation speed decreases
Solution Approach 1:
The patent introduces dynamic adjustment of transport block size through a scaling factor that can be applied to long TTI transport block sizes. This enables the system to dynamically adapt to short TTI requirements while maintaining the structural benefits of long TTI error correction designs, allowing flexible optimization between reliability and latency.
3Device complexity
If existing long TTI transport block size tables are used for short TTI, then device complexity is reduced, but transmission efficiency is reduced due to mismatched block sizes
Solution Approach 1:
The patent applies parameter transformation by introducing a scaling factor that modifies long TTI transport block sizes to suit short TTI transmission. This allows reuse of existing long TTI tables with a simple mathematical adjustment, maintaining transmission efficiency while avoiding the complexity of separate short TTI tables.
Solution Approach 2:
The scaling factor acts as an intermediary that bridges between long TTI transport block size tables and short TTI transmission requirements. This intermediary element enables efficient transmission adaptation without requiring separate optimization tables, resolving the contradiction between device complexity and transmission efficiency.
Data Source
AI summary
A method performed by a communication device comprises identifying a long transmission time interval (TTI) transport block size from a set of long TTI transport block sizes used for transport block transmission within a long TTI. The method further comprises determining a short TTI transport block size, used for transport block transmission within a short TTI, by downscaling the long TTI transport block size based on a relation between a number of symbols in the short TTI and a number of symbols in the long TTI that is greater than the number of symbols in the short TTI.