Grant-Free Uplink Configuration for URLLC Latency
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Solution Overview
Problem
Current designs for semi-persistent scheduling (SPS) and grant-free transmissions in 5G wireless communication systems are insufficient for meeting the latency and reliability requirements of ultra-reliable low latency communications (URLLC) applications, particularly in subsequent retransmissions, which often require additional control signaling increasing overhead and latency.
Innovation Solution
The system allows user equipment (UE) to receive multiple configurations for grant-free communications, enabling it to select and perform communications based on different latency conditions, modulation and coding schemes, and service types, including both initial and subsequent transmissions, thereby reducing control signaling and enhancing reliability and latency performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional control signaling is used for subsequent retransmissions in SPS/grant-free transmissions, then reliability is improved, but overhead and latency increase
Solution Approach 1:
The patent extracts the control signaling requirement from subsequent retransmissions by enabling the UE to autonomously perform retransmissions using pre-configured resources without requiring additional downlink control information (DCI) or uplink grants. This removes the overhead and latency associated with control signaling while maintaining reliability through configured grant resources.
Solution Approach 2:
The patent applies preliminary action by pre-configuring multiple grant-free resources and parameters (including redundancy versions, modulation and coding schemes, and time-frequency resources) before transmission begins. This allows the UE to immediately perform retransmissions without waiting for control signaling, reducing latency while ensuring reliability through pre-planned transmission parameters.
2Adaptability or versatility
If multiple configurations are provided for grant-free communications, then adaptability to different latency conditions is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by providing different configuration sets tailored to specific latency conditions and service types. Each configuration set contains optimized parameters (such as different redundancy versions, MCS indices, and time-resource allocations) suited for particular transmission scenarios, allowing the UE to select the most appropriate configuration for current channel and latency conditions without managing unnecessary complexity.
3Loss of substance
If grant-free transmissions are used for subsequent retransmissions, then control signaling overhead is reduced, but configuration complexity increases
Solution Approach 1:
The patent segments the configuration into multiple independent configuration sets, each corresponding to different latency conditions or service types. This segmentation allows the network to provide granular control over retransmission parameters without requiring complex monolithic configurations. The UE can select and apply appropriate segments based on current conditions, reducing both control signaling overhead and configuration complexity through modular design.
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AI summary
Techniques and apparatus for enhancing uplink grant-free transmissions and/or downlink semi-persistent scheduling (SPS) transmissions for uplink ultra-reliable low latency communications (URLLC) are described. One technique includes receiving a first configuration for a first grant-free communication and a second configuration for at least one second grant-free communication. Grant-free communications are performed based on at least one of the first configuration or the second configuration