Transport Block Size Scaling for Shortened Subframes
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Solution Overview
Problem
Existing TBS tables defined for fixed-length subframes are inadequate for supporting shortened subframes, leading to reduced resource elements for data transmission and inability to maintain performance and capacity in communications networks.
Innovation Solution
A method to determine Transport Block Size (TBS) values efficiently for short subframes by reusing existing TBS tables and link adaptation algorithms, allowing for flexible subframe durations and maintaining performance without modifying standardization specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If subframe length is shortened to reduce packet latency, then packet latency is improved, but the number of available resource elements for data transmission is reduced
Solution Approach 1:
The patent applies parameter changes by scaling the Transport Block Size (TBS) index based on the ratio of actual subframe length to reference subframe length. This allows the system to adapt TBS values dynamically for shortened subframes while maintaining compatibility with existing TBS tables, thereby resolving the contradiction between reduced latency and available resource elements.
2Device complexity
If existing TBS tables are reused for shortened subframes, then device complexity is reduced, but manufacturing precision of TBS values deteriorates
Solution Approach 1:
The patent introduces a TBS index scaling mechanism as an intermediary between the existing TBS tables and the actual TBS values needed for shortened subframes. This mediator allows reuse of existing tables while achieving precise TBS determination through mathematical scaling of the TBS index based on subframe length ratios.
3Manufacturing precision
If new TBS tables are created for shortened subframes, then manufacturing precision of TBS values is improved, but device complexity increases
Solution Approach 1:
The patent makes the existing TBS tables universal by applying a scaling factor to the TBS index that accounts for different subframe lengths. This allows a single set of TBS tables to serve multiple subframe durations (both legacy and shortened), eliminating the need for separate tables while maintaining precision through the scaling mechanism.
Data Source
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AI summary
There is provided mechanisms for transmitting payload in a subframe. A method is performed by a first network device. The method comprises obtaining a transport block size (TBS) value by accessing an array storing a plurality of TBS values. The TBS value is proportional to number of user data symbols in a subframe of a given subframe length. One and the same array is accessed regardless of the given subframe length. The method comprises transmitting a physical channel carrying payload in the subframe to a second network device. The amount of data in the payload is determined by the TBS value.