HARQ Process Identification for Non-Terrestrial Networks
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Solution Overview
Problem
In non-terrestrial networks, the high round-trip delay and limited buffering capabilities of user equipment (UE) pose challenges for supporting a sufficient number of concurrent HARQ processes, which is necessary for acceptable data throughput, especially when communicating with satellites.
Innovation Solution
The method involves calculating a HARQ process number using a combination of the HARQ process ID and slot number, allowing for an increased number of concurrent HARQ processes by using a virtual slot counter, and optimizing soft buffer management to accommodate the increased load, while keeping the HARQ bits in the DCI to a minimum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of HARQ processes is increased to provide acceptable data throughput in non-terrestrial networks, then data throughput is improved, but the buffering capabilities of the UE are strained
Solution Approach 1:
The patent extends the HARQ process identification from a single 4-bit field to a multi-dimensional structure combining 4-bit HARQ process ID with a 5-bit slot counter, effectively adding a time dimension to the process identification. This allows the system to distinguish between more HARQ processes (up to 64 concurrent processes) without increasing the DCI field size, thereby improving data throughput while managing UE buffering capabilities through efficient process multiplexing.
2Productivity
If the number of HARQ processes is increased to support high data throughput, then data throughput is improved, but the number of HARQ bits in DCI must be increased
Solution Approach 1:
The patent segments the HARQ process identification into two independent components: a 4-bit HARQ process ID field (unchanged) and a 5-bit slot counter (added separately). This segmentation allows the system to support more HARQ processes by combining the two components rather than simply expanding the DCI field, thereby maintaining DCI efficiency while enabling up to 64 concurrent HARQ processes for improved data throughput.
3Productivity
If a virtual slot counter is introduced to calculate HARQ process numbers, then the number of concurrent HARQ processes is increased, but system complexity is increased
Solution Approach 1:
The slot counter is implemented as a self-service mechanism that automatically increments with each slot and wraps around after 32 slots. This automatic counter eliminates the need for complex external synchronization or manual configuration, allowing the UE to independently generate unique HARQ process numbers for up to 64 concurrent processes. The self-service approach improves productivity while keeping the added complexity minimal through simple hardware-based counting.
Data Source
AI summary
A hybrid automatic repeat request (HARQ) process method for nonterrestrial networks. In some embodiments, the method includes receiving, by a user equipment (UE), a first downlink control information (DCI), the first DCI including a first hybrid automatic repeat request (HARQ) process identifier (ID); calculating a first HARQ process number based on the first HARQ process ID and on a slot number associated with the first DCI; and processing a first data block via a HARQ process associated with the first HARQ process number.