NTN Uplink HARQ Process Selection for High-RTT Overhead Control
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Solution Overview
Problem
In NTN communications, the high round trip time leads to increased overhead in HARQ processes, necessitating a solution for selectively enabling and disabling UL HARQ retransmission to optimize performance.
Innovation Solution
A method for selectively enabling and disabling UL HARQ retransmission in NTN communications by determining specific UL HARQ processes for logical channels and MAC Control Elements, and indicating support for retransmission through Uplink Control Information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of HARQ processes is increased to many times above 16 to achieve target throughput under high RTD conditions in NTN systems, then the throughput performance is improved, but the overhead in UE increases significantly
Solution Approach 1:
The patent segments the 16 HARQ processes into different groups based on their retransmission status. Some HARQ processes are configured with retransmission enabled while others have retransmission disabled, allowing selective usage based on traffic requirements and reducing the effective number of processes needed
Solution Approach 2:
The patent introduces dynamic configuration where the network can selectively enable or disable UL HARQ retransmission for different HARQ processes based on real-time conditions. This dynamic adjustment allows the system to adapt the number of active HARQ processes according to actual throughput needs, avoiding the static overhead of maintaining all 16 processes active
2Quantity of substance
If UL HARQ retransmission is disabled for certain HARQ processes to reduce overhead, then the overhead is reduced, but the reliability of data transmission may be affected
Solution Approach 1:
The patent applies different retransmission configurations to different HARQ processes based on local requirements. Critical data transmissions can use HARQ processes with retransmission enabled, while less critical traffic can use processes with retransmission disabled, optimizing the balance between overhead and reliability on a per-process basis
Solution Approach 2:
The patent implements feedback mechanisms where the network monitors the performance of HARQ processes with disabled retransmission and can dynamically adjust configurations. If transmission reliability falls below thresholds, the system can reactivate retransmission for specific processes, ensuring reliability is maintained while minimizing overhead
3Loss of time
If the round trip time is reduced in NTN systems, then the latency is reduced, but the physical distance constraints of satellite communication make this difficult without increasing HARQ processes
Solution Approach 1:
The patent applies partial action by enabling HARQ retransmission only for the specific number of processes needed rather than configuring all 16 processes. By calculating the minimum required HARQ processes based on throughput requirements and RTD conditions, the system achieves adequate latency performance with reduced process management complexity
Data Source
AI summary
Methods for selectively enabling and disabling UL HARQ retransmission in NTN communications and communication apparatus utilizing the same. A method for selectively enabling and disabling uplink Hybrid Automatic Repeat request (HARQ) retransmission in Non-Terrestrial Network (NTN) communications includes: determining a set of logical channels that are allowed to transmit or a set of MAC CEs that are allowed to be transmitted using one or more specific uplink (UL) HARQ processes. The one or more specific UL HARQ processes include one or more UL HARQ processes for which the UL retransmission has been disabled, or one or more UL HARQ processes for which the UL retransmission has been enabled.