UE HARQ Process Handling for Random Access Msg3 Transmissions
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Solution Overview
Problem
In wireless communication systems, particularly in LTE and NR networks, the handling of transmissions during a random access procedure is inefficient due to issues with configured grants and HARQ processes, leading to potential errors and insufficient retransmission opportunities for Msg3 transmissions, especially when configured grants overlap with random access procedures.
Innovation Solution
A User Equipment (UE) determines whether to use a HARQ process for transmissions via configured or dynamic grants based on the type of grant, triggering event, and logical channel priority, and manages timers such as configuredGrantTimer and ra-ContentionResolutionTimer to ensure proper handling of Msg3 transmissions and retransmissions during random access procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If configured grants are used for uplink transmissions, then resource utilization is improved, but transmission reliability deteriorates when configured grants overlap with random access procedures
Solution Approach 1:
The system dynamically adjusts the behavior of configured grants based on the state of random access procedures. When a random access procedure is detected, the configured grant transmission is suspended or modified. This dynamic adaptation allows the system to maintain high resource utilization during normal operation while ensuring transmission reliability during random access procedures by temporarily modifying grant behavior.
Solution Approach 2:
The system performs preliminary detection of random access procedure states before configured grant transmissions occur. By monitoring for ongoing random access procedures in advance, the system can preemptively adjust or suspend configured grant transmissions to prevent conflicts, ensuring that Msg3 transmissions are not accidentally overwritten and maintaining transmission reliability.
2Reliability
If HARQ processes are used for configured grants, then retransmission capability is improved, but transmission errors increase when overlapping with random access procedures
Solution Approach 1:
The system extracts or separates the HARQ process handling for configured grants from the random access procedure handling. When a random access procedure is detected, the system suspends HARQ-related operations for configured grants, preventing the harmful interaction where HARQ retransmissions could conflict with random access transmissions. This separation eliminates the source of transmission errors while preserving HARQ capabilities for non-overlapping transmissions.
3Productivity
If Msg3 buffer is overwritten by configured grant MAC PDU, then resource efficiency is improved, but retransmission opportunities are lost
Solution Approach 1:
The system applies preliminary anti-action by detecting the presence of ongoing random access procedures before configured grant transmissions occur. When such procedures are detected, the system prevents the overwriting of Msg3 buffers by suspending or modifying configured grant transmissions. This preventive measure protects critical random access data from being accidentally overwritten, ensuring retransmission opportunities are preserved while minimizing impact on overall resource efficiency.
Data Source
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AI summary
Methods and apparatuses for handling transmission during a random access procedure are disclosed herein. In one method, the UE initiates a random access, RA, procedure (2305). The UE receives a RA response during the RA procedure, wherein the RA response indicates a first uplink, UL, grant for the UE to perform a Msg3 transmission by a specific hybrid automatic repeat request, HARQ, process (2310). The UE receives a second UL grant for the UE to perform a specific transmission, wherein the specific transmission is to be performed during the RA procedure (2315). The UE determines whether to perform the specific transmission based on at least whether the specific transmission is to be performed by the specific HARQ process used for the Msg3 transmission, wherein the Msg3 transmission and the specific transmission are not overlapped in a time domain (2320).