Terminal Apparatus HARQ Process ID Determination for URLLC
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Solution Overview
Problem
In 5G communication systems, terminal apparatuses face challenges in efficiently managing data transmission for grant-free access in Ultra-Reliable Low Latency Communications (URLLC), particularly in identifying the correct Process Identifier (PID) for retransmissions, leading to inefficient process management.
Innovation Solution
A terminal apparatus and communication method that utilize RRC information to determine HARQ process IDs for data transmission, allowing for efficient retransmissions by associating process IDs with time and frequency radio resources, and switching between grant-free and scheduled access based on ACK/NACK responses and timer expiration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If grant-free access is used for data transmission, then latency is reduced and overhead is suppressed, but process management becomes difficult without proper PID indication
Solution Approach 1:
The terminal apparatus autonomously determines the HARQ process ID by calculating it from the slot index and number of HARQ processes, without requiring explicit indication from the base station. This self-service mechanism eliminates the need for additional control signaling while enabling proper process management in grant-free access
Solution Approach 2:
The patent changes the parameter determination method from receiving explicit PID indication to calculating PID based on slot index and number of HARQ processes. This parameter transformation enables the terminal to autonomously manage HARQ processes while maintaining consistency with base station expectations
2Device complexity
If scheduled access is used for data transmission, then process management is easier with explicit control, but control information overhead increases
Solution Approach 1:
The patent extracts the PID indication function from explicit control signaling and embeds it into the time resource structure through slot index-based calculation. This extraction eliminates unnecessary control overhead while preserving process management capability
Solution Approach 2:
The slot index serves multiple functions: it identifies the time resource for data transmission and simultaneously determines the HARQ process ID. This multi-functionality reduces the need for separate PID indication signaling
3Reliability
If scheduled access is used for data transmission, then uplink resources are controlled by base station, but transmission delay increases due to UL Grant reception requirement
Solution Approach 1:
The base station pre-configures the terminal with the number of HARQ processes and slot index information through RRC signaling before data transmission. This preliminary configuration enables the terminal to immediately determine the correct HARQ process ID without waiting for UL Grant reception, reducing transmission delay while maintaining resource control
Data Source
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AI summary
A terminal apparatus includes a transmitter configured to transmit PUSCH data and a receiver configured to receive RRC information. The transmitter transmits the PUSCH data by using a resource associated with an HARQ process ID determined by symbol information for transmission of the PUSCH data, a period, and the number of HARQ processes. In a case that the receiver receives no response to the transmission of the PUSCH data with the HARQ process ID after the transmission of the PUSCH data is performed and before a timer included in the RRC information expires, the transmitter transmits new PUSCH data by using the resource associated with the HARQ process ID determined by the symbol information for the transmission of the PUSCH data, the period, and the number of HARQ processes.