Two-Stage Scheduling Grant for NR-U Uplink Latency
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing uplink data transmissions in shared communication mediums, particularly due to delays between receiving scheduling grants and initiating data transmissions, which can lead to inefficient use of bandwidth and processing timelines.
Innovation Solution
A two-stage scheduling grant mechanism is introduced, where a first scheduling grant is transmitted in one transmission opportunity (TXOP) and a second scheduling grant, including a start slot index (SSI) or slot format indicator (SFI), is transmitted in a subsequent TXOP, allowing the UE to prepare and transmit an uplink communication signal based on both grants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single scheduling grant is used for uplink data transmission, then the system is simpler to implement, but processing timeline delays increase and bandwidth utilization decreases
Solution Approach 1:
The scheduling grant is divided into two separate stages: a first scheduling grant that provides initial resource allocation information, and a second scheduling grant that provides final transmission parameters including start slot index. This segmentation allows the UE to begin preparing data earlier while waiting for the second grant, reducing overall processing delay without significantly increasing system complexity.
Solution Approach 2:
The first scheduling grant enables preliminary actions by the UE, such as buffering data and performing initial processing, before the second scheduling grant is received. This preliminary action reduces the critical path delay by overlapping preparation activities with the waiting period for the second grant.
2Loss of information
If a single scheduling grant is used for uplink data transmission, then the signaling overhead is reduced, but bandwidth utilization decreases due to idle medium time
Solution Approach 1:
The scheduling information is segmented into two grants transmitted at different times. The first grant contains resource allocation details that enable early data preparation, while the second grant contains timing parameters. This allows the medium to be utilized more efficiently by reducing idle time between grant reception and data transmission.
Solution Approach 2:
The two-stage grant mechanism enables continuous useful action by keeping the UE in a prepared state between the first and second grants, rather than idle. The UE can continuously process and buffer data during this interval, ensuring that when the second grant arrives, transmission can begin immediately, maximizing bandwidth utilization.
3Reliability
If the UE waits for a single scheduling grant before transmitting, then transmission accuracy is ensured, but processing timeline delays increase
Solution Approach 1:
The reliability checks are distributed across two grants. The first grant provides initial resource allocation that the UE can verify immediately, allowing early error detection. The second grant provides final timing parameters that trigger actual transmission. This segmentation maintains transmission accuracy while reducing the overall waiting time by enabling parallel verification and preparation activities.
Data Source
AI summary
Wireless communications systems and methods related to communicating in a communication medium are provided. A first wireless communication device communicates with a second wireless communication device, a first scheduling grant. The first wireless communication device communicates, with the second wireless communication device, a second scheduling grant including at least one of a start slot index (SSI) or a slot format indicator (SFI). The first wireless communication device communicates, with the second wireless communication device, an uplink communication signal based on the first scheduling grant and the second scheduling grant.