Uplink Grant-Free Transmission Block Indication Handling
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Solution Overview
Problem
Current 5G proposals for uplink grant-free transmissions in URLLC scenarios face inefficiencies due to UE's inability to determine whether a received UL grant is for retransmission or new transmission, leading to increased errors, latency, and resource wastage, as UE is restricted from transmitting multiple transport blocks within the same TTI.
Innovation Solution
The UE device is configured to analyze the UL grant's transport block size and new data indicator bits to determine whether to retransmit a previously sent transport block or transmit a new one, allowing for autonomous selection of HARQ process ID and decision-making based on the UL grant's timing and bit fields, enabling efficient link adaptation and resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the UE is prohibited from transmitting two or more TBs during the same TTI to simplify the transmission protocol, then the device complexity is reduced, but the productivity decreases because the UE cannot efficiently utilize uplink resources and must wait for grant responses before transmitting additional data
Solution Approach 1:
The patent introduces dynamic TB handling mechanisms where the UE can adaptively switch between different transmission modes (grant-free and grant-based) and dynamically manage multiple TBs based on received grants. The system allows dynamic determination of whether to retransmit previous TBs or transmit new TBs based on NDI values and grant timing, enabling flexible resource utilization without permanent protocol complexity
Solution Approach 2:
The patent changes the state parameters of TB transmission by introducing explicit indicators (NDI bits) and timing-based parameters that allow the UE to distinguish between retransmission and new transmission grants. By modifying the grant structure to include these parameters, the system enables multiple TB transmissions while maintaining manageable complexity through clear state differentiation
2Reliability
If the UE resends the first TB using the received UL grant when unable to determine the grant target, then the reliability of data transmission is improved, but the loss of time increases due to unnecessary retransmissions and increased latency
Solution Approach 1:
The patent implements feedback mechanisms where the BS provides explicit information (NDI bits, grant timing) to the UE that enables the UE to accurately determine whether a grant is for retransmission or new transmission. This feedback loop eliminates the need for blind retransmission decisions, allowing the UE to correctly identify grant targets and avoid unnecessary retransmissions while maintaining high reliability
Solution Approach 2:
The patent applies preliminary action by having the BS pre-configure grant structures with identifying information (NDI values, timing relationships) before transmission. This allows the UE to proactively determine grant targets without ambiguity, preventing unnecessary retransmissions and reducing latency while ensuring reliable delivery
3Reliability
If the UE ignores all UL grants received during a time window to avoid transmission errors, then the reliability is improved by preventing incorrect retransmission decisions, but the productivity decreases due to inefficient resource usage and poorer link adaptation
Solution Approach 1:
The patent uses feedback in the form of explicit NDI indicators and timing information provided by the BS to enable the UE to accurately distinguish between grants intended for retransmission and grants for new transmissions. This feedback mechanism allows the UE to confidently process and act on valid grants without making incorrect retransmission decisions, thereby maintaining high reliability while improving resource utilization
Solution Approach 2:
The patent applies preliminary action by having the BS pre-mark grants with identifying information (NDI values, timing relationships) that allow the UE to proactively and accurately determine grant intent. This eliminates the need to ignore grants while preventing incorrect retransmissions, achieving both high reliability and efficient resource usage
Data Source
AI summary
A system, apparatus, method, and non-transitory computer readable medium for providing transfer block indications in uplink (UL) grant-free transmissions may include a memory having computer readable instructions stored thereon, and at least one processor configured to execute the computer readable instructions to transmit a first transport block (TB) to a base station (BS) during a first transmission time interval (TTI) using a grant-free UL transmission, receive a UL grant from the BS in a physical downlink control channel (PDCCH) region during a time window, determine a target of the UL grant, the target including at least one of the first TB, a second TB, or a previously transmitted TB, based on the UL grant, and transmitting the target of the UL grant to the BS.