D2D Control Channel Specific Bit for TTI Length Sensing
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Solution Overview
Problem
In vehicle-to-everything (V2X) communication systems, terminals from different 3GPP Release versions (14 and 15) face challenges in determining whether a control channel is transmitted by a Release-14 or Release-15 terminal, affecting resource sensing and selection due to differences in transmission time intervals (TTIs) and the inability to distinguish between normal and short control channels.
Innovation Solution
Incorporating a specific bit in the control channel to indicate the length of the time domain used for data channel transmission, allowing terminals to determine the appropriate TTI for resource sensing based on the bit's value, enabling effective resource occupancy determination and sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a terminal transmits two types of control channels simultaneously (normal control channel and short control channel) to support both Release-14 and Release-15 protocols, then the system compatibility and adaptability are improved, but the device complexity and difficulty of detecting and measuring increase because the receiving terminal cannot determine which type of control channel is being transmitted
Solution Approach 1:
The patent uses a specific bit in the control channel to indicate the TTI length type, analogous to using different colors to distinguish between normal control channels and short control channels. This allows the receiving terminal to quickly identify the control channel type without increasing structural complexity, resolving the contradiction between maintaining dual-protocol compatibility and enabling easy channel type detection
Solution Approach 2:
The patent introduces a specific bit as an intermediary indicator within the control channel structure. This bit acts as a mediator that carries information about the TTI length type, allowing the receiving terminal to distinguish between normal and short control channels without requiring complex detection mechanisms, thus resolving the identification difficulty while maintaining system adaptability
2Reliability
If the terminal uses a normal control channel with TTI-based transmission, then the system compatibility with Release-14 terminals is maintained, but the transmission delay increases compared to using short control channels with sTTI-based transmission
Solution Approach 1:
The patent implements dynamic control channel selection where the terminal can adaptively choose between normal control channels (TTI-based) and short control channels (sTTI-based) based on the specific communication scenario, terminal capabilities, and delay requirements. This dynamic approach allows the system to maintain compatibility with Release-14 terminals when necessary while achieving lower transmission delays with Release-15 terminals, thus resolving the contradiction between reliability and time loss
Solution Approach 2:
The patent changes the TTI length parameter dynamically by introducing short TTIs (sTTIs) as an alternative to normal TTIs. The specific bit in the control channel indicates whether the TTI length is normal or short, allowing the system to adjust the time parameter based on communication requirements. This parameter change enables reduced transmission delay for Release-15 terminals while maintaining compatibility options for Release-14 terminals
Data Source
AI summary
The present disclosure provides a D2D communication method, including: a first terminal device receives a control channel transmitted by a second terminal device on a first transmission time interval TTI, where the control channel includes a specific bit, and the specific bit is used to indicate a length of time domain used by the second terminal device for transmitting a data channel; the first terminal device senses the data channel transmitted by the second terminal device based on the first TTI if a value on the specific bit indicates that the length of time domain is equal to a length of the first TTI; and the first terminal device senses the data channel transmitted by the second terminal device based on a second TTI if the value on the specific bit indicates that the length of time domain is equal to a length of the second TTI.