Open Loop HARQ Logical Channel Prioritization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The high round trip delay (RTD) in non-terrestrial networks, such as satellite communications, affects the ability of wireless transmit/receive units (WTRUs) to maintain high data rate services, as RTDs for Low Earth Orbit, Medium Earth Orbit, and Geosynchronous Earth Orbit satellites are significantly longer compared to terrestrial networks, impacting HARQ processes and communication reliability.
Innovation Solution
Implementing logical channel prioritization and hybrid automatic repeat request (HARQ) processing type determination in WTRUs, where HARQ processing types (closed-loop, open-loop, or stateless) are associated with specific HARQ processes and logical channels, allowing for dynamic configuration and restriction based on RTD conditions, enabling efficient data transmission and error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional HARQ processes are used in non-terrestrial networks, then communication protocols can be simplified, but communication reliability deteriorates due to high round trip delay
Solution Approach 1:
The patent applies dynamics by making the HARQ process configurable between closed-loop and open-loop modes based on RTD conditions. The system dynamically selects the appropriate HARQ processing type according to the specific non-terrestrial network scenario and channel conditions, allowing adaptation to varying delay characteristics without requiring complete protocol redesign.
Solution Approach 2:
The patent changes key HARQ parameters including the number of HARQ processes, buffer sizes, and processing timing based on the round trip delay characteristics of different orbital scenarios. By adjusting these parameters according to specific RTD values, the system optimizes performance for each non-terrestrial network deployment while maintaining protocol compatibility.
2Reliability
If HARQ feedback is transmitted in every uplink slot, then error correction reliability is improved, but uplink resource consumption increases
Solution Approach 1:
The patent implements partial action by transmitting HARQ feedback only in selected uplink slots rather than every slot. The system determines optimal feedback transmission opportunities based on channel conditions, data priority, and buffer status, sending feedback selectively to maintain reliability while reducing overall uplink resource consumption in high-latency non-terrestrial environments.
3Productivity
If the number of HARQ processes is increased to support high data rates, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent segments the HARQ process management into distinct functional modules including process selection, buffer management, and feedback generation. Each module handles specific aspects of HARQ operation independently, allowing the system to support multiple parallel HARQ processes for high data rates while maintaining manageable complexity through modular architecture and clear separation of concerns.
Data Source
AI summary
A WTRU may be configured to perform logical channel prioritization. A WTRU may receive an indication (e.g., a mapping) that indicates an association between a first HARQ process ID and a first HARQ processing type and between a second HARQ process ID and a second HARQ processing type. The WTRU may receive an indication (e.g., a mapping) that indicates an association between a first logical channel and the first HARQ processing type and between a second logical channel and the second HARQ processing type. The WTRU may receive an a HARQ process ID indication. The WTRU may determine a HARQ processing type associated with the HARQ process ID. The WTRU may determine a logical channel available for a transmission. The logical channel available to be used may be determined based on the HARQ processing type associated with the HARQ process ID. The WTRU may send the transmission.