Uplink HARQ Repetition Scheduling for Low-Latency URLLC
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Solution Overview
Problem
Current wireless communication systems face challenges in achieving ultra-reliable and low-latency communications (URLLC) due to limitations in communication flexibility and efficiency, particularly in designing hybrid automatic repeat request (HARQ) mechanisms that meet stringent latency and reliability requirements for uplink transmissions.
Innovation Solution
The implementation of a hybrid automatic repeat request (HARQ) mechanism for uplink URLLC communications, which includes various transmission types such as scheduling request-triggered, fast grant-based, grant-free, and semi-persistent scheduling, allowing for flexible and efficient resource allocation and repetition strategies to manage initial and retransmission transmissions without waiting for acknowledgments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional communication structures are used for uplink transmissions, then system complexity is reduced, but communication flexibility and efficiency are limited
Solution Approach 1:
The patent implements dynamic HARQ mechanisms where the base station can flexibly configure and adjust HARQ parameters (such as HARQ process IDs, resource allocations, and timing) based on real-time URLLC traffic conditions. This allows the system to adapt communication structures dynamically rather than using fixed traditional structures, thereby improving flexibility while managing complexity through intelligent control.
Solution Approach 2:
The patent changes key communication parameters including HARQ process identifiers, resource block allocations, and timing advance values to enable flexible uplink transmissions. By dynamically adjusting these parameters based on traffic demands and channel conditions, the system achieves improved adaptability without requiring fundamentally complex new communication structures.
2Reliability
If acknowledgment waiting is implemented for retransmissions, then transmission reliability is improved, but latency increases
Solution Approach 1:
The patent implements preliminary actions by pre-configuring multiple HARQ processes and pre-allocating uplink resources for potential retransmissions. The base station prepares acknowledgment resources and timing advance values in advance, allowing URLLC devices to perform retransmissions without waiting for individual acknowledgments, thereby reducing latency while maintaining reliability through pre-planned retransmission strategies.
Solution Approach 2:
The patent enables skipping of traditional acknowledgment waiting by implementing grant-free uplink transmissions where URLLC devices can send retransmissions immediately based on pre-configured parameters. This rushing through the acknowledgment phase is made possible by using multiple parallel HARQ processes and pre-scheduled resources, allowing the system to bypass the time-consuming acknowledgment waiting while maintaining transmission reliability.
3Loss of time
If grant-free transmission is used for URLLC, then latency is reduced, but resource allocation flexibility is reduced
Solution Approach 1:
The patent segments resource allocation into two parts: pre-configured grant-free resources for immediate URLLC transmissions (reducing latency) and dynamically adjustable parameters controlled by the base station (maintaining flexibility). By dividing resource management into fixed pre-configuration and dynamic parameter adjustment, the system achieves both low latency through grant-free access and resource allocation flexibility through base station control of HARQ parameters and resource configurations.
Data Source
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AI summary
A user equipment, UE, comprises: receiving circuitry (120) configured to receive a first radio resource control message including first information used for configuring a number of repetitions, the receiving circuitry (120) being configured to receive a second radio resource control message including second information used for configuring a time domain occasion for a symbol where the UE monitors an uplink grant with cyclic redundancy check scrambled by a first radio network temporary identifier, RNTI, in a UE-specific search space, wherein the first RNTI is different from a cell radio network temporary identifier, C-RNTI, and the receiving circuitry (120) being configured to monitor in the UE-specific search space, based on the second information, the uplink grant with the cyclic redundancy check scrambled by the first RNTI; and transmitting circuitry (158) configured to perform, based on a detection of the uplink grant with the cyclic redundancy check scrambled by the first RNTI, a transmission on a physical uplink shared channel according to the first information.