V2X HARQ Retransmission Using Dynamic Grants After NACK
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently utilizing configured grants for Hybrid Automatic Repeat and Request (HARQ) retransmissions in vehicle-to-everything (V2X) communication, particularly in scenarios requiring low latency and high reliability.
Innovation Solution
A method and apparatus for a user equipment (UE) that supports V2X communication, involving data transmission in a configured grant, responding to non-acknowledgement (NACK) with a new data indicator (NDI) value change based on a dynamically allocated grant for HARQ retransmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gNB transmits multiple PDSCHs to the same UE with different HARQ process IDs, then the UE can receive multiple downlink data transmissions, but the UE cannot correctly identify which HARQ process corresponds to which PDSCH transmission
Solution Approach 1:
The DCI message serves as an intermediary that carries the HARQ process ID information from the gNB to the UE. The DCI includes a HARQ process field that explicitly indicates which HARQ process the associated PDSCH transmission belongs to, enabling the UE to correctly identify and manage multiple concurrent downlink transmissions.
Solution Approach 2:
The HARQ process ID is predetermined and assigned to each PDSCH transmission before the actual data transmission occurs. This allows the UE to pre-configure the corresponding HARQ buffer and processing parameters, ensuring efficient and error-free reception of multiple simultaneous transmissions.
2Productivity
If the UE monitors PDCCH for multiple HARQ processes, then the UE can receive multiple downlink transmissions, but the PDCCH monitoring complexity and power consumption increase
Solution Approach 1:
The monitoring configuration is segmented by associating specific search space sets and CORESETs with specific HARQ process IDs. The UE can be configured to monitor only the relevant search spaces for its assigned HARQ processes, reducing the overall monitoring burden while maintaining the ability to receive multiple downlink transmissions.
3Productivity
If the network uses dynamic HARQ process allocation, then resource utilization improves, but the signaling overhead and processing complexity increase
Solution Approach 1:
The system implements feedback mechanisms where the UE reports HARQ acknowledgment status (ACK/NACK) for each received PDSCH transmission. The gNB uses this feedback to dynamically allocate HARQ process IDs for subsequent transmissions, optimizing resource utilization while maintaining manageable processing complexity through standardized feedback procedures.
Data Source
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AI summary
The present invention may provide a method for performing HARQ retransmission by a terminal supporting V2X communication in a wireless communication system. The method for performing HARQ retransmission may comprise the steps of: transmitting data by a transmission terminal in a pre-configured resource; receiving, by the transmission terminal, a NACK response to the data from a reception terminal; and retransmitting the data by the transmission terminal after changing an NDI value on the basis of a resource dynamically allocated from a base station.