Grant Repetition for URLLC Control Channel Reliability
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Solution Overview
Problem
Conventional wireless communication systems face challenges in providing ultra-reliable low-latency communications due to interference and noise, leading to unacceptable latency and error rates in mission-critical applications like URLLC, where traditional retransmission techniques are inadequate.
Innovation Solution
The system employs a base station to transmit repeated grants with different offset values in the time domain, allowing the UE to use soft combining techniques to improve decoding reliability, by indicating a grant repetition configuration through a parameter that specifies when and where to monitor for repeated grants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional retransmission techniques are used, then the system can recover from transmission errors, but the latency becomes unacceptable for URLLC applications
Solution Approach 1:
The base station transmits multiple copies of the same grant in advance before the actual data transmission is needed. This preliminary action ensures that the UE has already received and can immediately use the grant when data transmission is required, eliminating the need for error recovery retransmissions and reducing latency.
Solution Approach 2:
The base station transmits periodic repetitions of the grant at predetermined intervals. This periodic transmission pattern ensures that at least one copy of the grant reaches the UE within the required time window, providing reliability without requiring reactive retransmission protocols that increase latency.
2Reliability
If the base station transmits multiple repeated grants, then the UE can use soft combining to improve decoding reliability, but the downlink control channel resources increase
Solution Approach 1:
The base station transmits a limited number of grant repetitions (e.g., 2-4 copies) which is excessive enough to ensure at least one successful reception by the UE through soft combining, but not so excessive as to waste control channel resources. This partial action achieves the minimum necessary reliability improvement.
Solution Approach 2:
The system changes the parameter of grant repetition count based on channel conditions and URLLC requirements. By dynamically adjusting the number of repetitions, the system optimizes the balance between decoding reliability and control channel resource consumption, transmitting more repetitions only when necessary.
Data Source
AI summary
Methods, systems, and devices for wireless communication are described. A base station may identify a first grant repetition configuration of a plurality of grant repetition configurations for a user equipment (UE). The base station may generate a grant repetition parameter corresponding to the first grant repetition configuration. The base station may transmit the grant repetition parameter to the UE to indicate the first grant repetition configuration. The base station may transmit a repetition of grants in accordance with the first grant repetition configuration. The UE may receive the grant repetition parameter from the base station and determine a grant repetition configuration corresponding to the grant repetition parameter. The UE may monitor for a repetition of grants corresponding to the determined grant repetition configuration.