Terminal Device HARQ Process Determination for 5G URLLC
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Solution Overview
Problem
In ultra-reliable and low latency communications (URLLC) scenarios of 5G, determining the HARQ process used in repeated transmissions is challenging due to unpredictable start times of data transmissions and the lack of fixed resource allocation, leading to difficulties in detecting the first transmission and determining the correct HARQ process number for combining initially transmitted and retransmitted data.
Innovation Solution
A method where a terminal device determines a transmission time unit for the first transmission and uses a parameter Q to determine the HARQ process, ensuring repeated transmissions occur within a specific time frame, allowing the network device to accurately identify the HARQ process used by the terminal device, even if the first transmission is not detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal device uses grant-free transmission mechanism with repeated transmissions, then data transmission reliability is improved, but the base station cannot accurately determine the HARQ process number because the start time of transmission is unpredictable
Solution Approach 1:
The patent applies preliminary action by having the terminal device determine and transmit a first indication information before the actual data transmission. This indication information contains the HARQ process number or sufficient parameters to determine it, allowing the base station to prepare the correct HARQ process buffer in advance. This resolves the contradiction by ensuring the base station has all necessary information about the HARQ process before receiving the data, eliminating the uncertainty caused by unpredictable transmission start times.
Solution Approach 2:
The patent introduces an intermediary element - the first indication information - that mediates between the terminal device and base station. This indication information acts as a carrier that conveys HARQ process identification details from the terminal to the base station, enabling accurate HARQ process determination without requiring the base station to detect the transmission start time. This intermediary resolves the detection difficulty while maintaining the reliability benefits of repeated transmissions.
2Speed
If the base station uses blind detection to receive grant-free data, then transmission latency is reduced, but the base station cannot determine which HARQ process should combine the retransmitted data
Solution Approach 1:
The patent applies preliminary action by having the terminal device transmit the first indication information (containing HARQ process number or determination parameters) before the data transmission. This allows the base station to pre-identify the correct HARQ process and prepare the buffer, eliminating the need to search through multiple HARQ processes after blind detection. This resolves the contradiction by providing HARQ process identification information in advance, maintaining both low latency and correct data combination.
Solution Approach 2:
The patent introduces first indication information as an intermediary that carries HARQ process identification details from the terminal to the base station. This intermediary enables the base station to accurately identify which HARQ process should combine the data without increasing transmission latency. The indication information serves as a bridge that connects the blind detection capability with the need for precise HARQ process identification, resolving the information loss problem.
3Productivity
If the terminal device starts repeated transmissions immediately when data arrives, then transmission speed is improved, but the base station cannot detect the first transmission to determine HARQ process numbers
Solution Approach 1:
The patent applies preliminary action by having the terminal device transmit the first indication information before the actual data transmission begins. This preliminary transmission of indication information allows the base station to detect and record the HARQ process number before the data transmission starts. This resolves the contradiction by ensuring the base station has precise identification information about the first transmission, enabling accurate HARQ process determination while maintaining high transmission speed.
Solution Approach 2:
The patent introduces first indication information as an intermediary that is transmitted before the data transmission. This intermediary carries precise identification details about the first transmission (including HARQ process number), allowing the base station to accurately detect and record this information. The indication information acts as a precursor that enables precise measurement and identification without interfering with the subsequent high-speed data transmission.
Data Source
AI summary
This application discloses a method for repeated transmission and a terminal device. The method implemented by a terminal device includes: determining a transmission time unit used in the first transmission of to-be-transmitted data; determining, by the terminal device based on the determined transmission time unit and a parameter Q, a hybrid automatic repeat request HARQ process used to transmit the to-be-transmitted data, where Q is an integer greater than or equal to 1; and when repeated transmission of the to-be-transmitted data is not terminated before the first specific transmission time unit, performing, starting from the determined transmission unit, one transmission of the to-be-transmitted data in each transmission time unit by using the HARQ process until the last transmission of the to-be-transmitted data is performed in the first specific transmission time unit, where a period of the specific transmission time unit in a time domain resource is Q transmission time units.