V2X Transmission Method Using Shorter Subframes
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Solution Overview
Problem
The conventional LTE Rel-14 V2X technique has limitations in data transmission reliability and processing delay due to its 1ms subframe length, which is not sufficient for advanced Vehicle-to-Everything (V2X) communication requirements, necessitating a shorter subframe length and improved resource management.
Innovation Solution
The proposed solution involves a transmission method that uses shorter subframe lengths, such as slot-level or OFDM symbol-level, with enhanced resource selection and DMRS sequence management, allowing for improved reliability and reduced delay by supporting multiple physical layer formats and multi-antenna transmission modes, and includes mechanisms for generating and processing DMRS sequences to optimize data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LTE normal subframe (1ms) is used for data transmission, then the system maintains compatibility with conventional LTE Rel-14 V2X technique, but data transmission reliability is relatively low and transmission delay is relatively large
Solution Approach 1:
The patent segments the LTE normal subframe (1ms) into smaller time units including slots and OFDM symbols. This segmentation allows data transmission to occur in shorter time intervals, reducing transmission delay and improving reliability by enabling faster retransmission and more granular resource allocation.
Solution Approach 2:
The patent introduces dynamic subframe length adjustment, allowing the system to switch between conventional 1ms subframes and shorter subframes (slot-level or symbol-level) based on V2X communication requirements. This dynamic adaptation enables the system to optimize between compatibility and performance needs.
2Reliability
If shorter subframe length (slot-level or OFDM symbol-level) is introduced, then processing delay is reduced and reliability is improved, but resource management complexity increases
Solution Approach 1:
The patent changes the time granularity parameter from 1ms subframe level to slot-level or OFDM symbol-level. This parameter change enables shorter transmission intervals and improved reliability while the system manages the increased complexity through standardized resource allocation procedures and DMRS sequence management.
3Reliability
If DMRS sequence is determined according to CRC bit in SA information, then legacy UE can determine occupied state using joint manner, but the process becomes complex and resource sensing is affected
Solution Approach 1:
The patent extracts the DMRS sequence determination from the joint determination process (SA information + CRC bit) and makes it independent through explicit indication in SA information. This extraction simplifies the resource sensing process for legacy UEs while maintaining accurate occupied state detection, as UEs only need to follow the explicitly indicated DMRS sequence without complex joint analysis.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
The present disclosure provides a transmission method and a transmission device. The transmission method includes: determining, by a transmitting end device, first SA information and first data to be transmitted, the first SA information at least including indication information about a DMRS sequence for the demodulation of the first data; and transmitting, by the transmitting end device, the first SA information in a first physical layer format and transmitting the first data in a second physical layer format. The first physical layer format for transmitting the first SA information and the second physical layer format for transmitting the first data are each a transmission format supporting a shorter subframe length, e.g., a transmission format with a slot-level TTI or an OFDM symbol-level TTI, so it is able to improve the data transmission reliability and reduce the transmission delay.