Sidelink Transport Block Sizing with Adaptive DMRS Allocation
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Solution Overview
Problem
The existing method for determining transport block size in vehicle-to-everything (V2X) communication systems is not applicable due to differences in frame structure, leading to inefficiencies in channel estimation and transmission reliability.
Innovation Solution
A method and apparatus for determining transport block size that adjusts the number of DMRS symbols based on channel state changes, allowing for consistent RE allocation across initial and retransmissions, ensuring improved channel estimation accuracy and transmission reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of DMRS symbols is fixed for all transmissions, then the transport block size determination is simple, but the channel estimation accuracy cannot be adapted to changing channel conditions
Solution Approach 1:
The patent applies dynamics by making the number of DMRS symbols adjustable based on channel conditions. The system transitions from a fixed DMRS configuration to a dynamic one where the number of DMRS symbols can be increased or decreased according to channel state changes, allowing the channel estimation accuracy to adapt to varying transmission environments while maintaining reasonable system complexity through standardized adjustment procedures.
Solution Approach 2:
The patent changes the parameter of DMRS symbol quantity from a fixed value to a variable parameter that can be adjusted based on channel conditions. By modifying this key parameter, the system achieves adaptive channel estimation accuracy without fundamentally changing the TBS determination mechanism, thus resolving the contradiction between measurement precision and device complexity.
2Reliability
If different numbers of DMRS symbols are used for initial transmission and retransmission, then channel estimation accuracy improves under varying channel conditions, but the transport block size determination becomes inconsistent
Solution Approach 1:
The patent segments the transmission process into distinct phases (initial transmission and retransmission) with different DMRS configurations. By allowing separate optimization of DMRS symbol numbers for each phase, the system achieves both consistent TBS determination (through standardized procedures in each phase) and improved transmission reliability (through adaptive DMRS allocation based on channel conditions).
Solution Approach 2:
The system dynamically adjusts the number of DMRS symbols between initial transmission and retransmission based on channel state feedback. This dynamic adaptation enables the system to maintain TBS determination consistency through standardized procedures while simultaneously improving transmission reliability by allocating appropriate DMRS resources according to actual channel conditions.
3Measurement precision
If more DMRS symbols are allocated, then channel estimation accuracy improves, but the available REs for data transmission decreases
Solution Approach 1:
The patent implements a dynamic balance between DMRS symbol allocation and data throughput by adjusting the number of DMRS symbols based on channel conditions. When channel conditions are poor, more DMRS symbols are allocated to improve estimation accuracy; when conditions are good, fewer DMRS symbols are used to maximize data throughput. This dynamic adjustment resolves the contradiction between measurement precision and productivity.
Solution Approach 2:
The system changes the parameter of DMRS symbol quantity to optimize the trade-off between channel estimation accuracy and data transmission throughput. By adjusting this parameter based on channel state, the system achieves optimal performance in both aspects rather than being constrained by a fixed allocation, thus resolving the contradiction between measurement precision and productivity.
Data Source
AI summary
A method for determining a transport block size includes: determining an overhead of a sidelink data channel PSSCH demodulation reference signal (DMRS) in a physical resource block (PRB) of a first time-frequency resource, where the first time-frequency resource includes a first time unit in time domain; and determining, based on the overhead of the PSSCH DMRS, a number of resource elements (REs) on the first time-frequency resource that are for data transmission, where the number of REs for data transmission is for determining a transport block size (TBS) of the sidelink data channel PSSCH. The method provides a combined gain of a plurality of transmissions of a same transport block, and supports DMRS configurations of different quantities of DMRS symbols in initial transmission and retransmission of one transport block.