Dynamic HARQ Feedback for Non-Terrestrial Network Contention
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently resolving contention in contention-based random access procedures, particularly in non-terrestrial networks, where latency and power consumption are high due to the lack of flexible HARQ feedback mechanisms.
Innovation Solution
The implementation of a method that disables HARQ feedback for random access procedures, allowing for early contention resolution by transmitting a contention resolution MAC-CE without msg4, and enabling HARQ feedback based on specific indications, thereby reducing latency and improving resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ feedback is enabled for random access procedures, then reliability of data transmission is improved, but latency and power consumption increase
Solution Approach 1:
The system dynamically switches between HARQ feedback enabled and disabled modes based on the specific random access procedure requirements. The base station can configure different HARQ feedback behaviors for different UEs or different random access scenarios, allowing optimal balance between reliability and latency for each case
Solution Approach 2:
The patent changes the HARQ feedback parameter from a fixed enabled state to a configurable state that can be set to enabled or disabled. This parameter change allows the system to adapt to different network conditions and service requirements, reducing latency when high reliability is not critical
2Reliability
If HARQ feedback is enabled for random access procedures, then transmission reliability is improved, but power consumption increases
Solution Approach 1:
The UE dynamically adjusts its HARQ feedback behavior based on network configuration and service requirements. When configured to disable HARQ feedback for certain random access procedures, the UE saves significant power by not monitoring downlink control channels and not transmitting feedback signals
Solution Approach 2:
The HARQ feedback parameter is changed from a mandatory enabled state to a configurable state. The base station can set this parameter to disabled for UEs or procedures where power saving is prioritized over maximum transmission reliability
3Loss of time
If early contention resolution is implemented without msg4, then latency is reduced, but device complexity increases
Solution Approach 1:
The patent extracts the contention resolution functionality from the traditional four-step random access procedure by implementing it within the three-step procedure. The contention resolution MAC-CE is transmitted in msg3 or in a separate downlink transmission, eliminating the need for msg4 while maintaining contention resolution capability
Solution Approach 2:
Contention resolution is performed preliminarily within the three-step procedure rather than requiring the complete four-step sequence. The base station includes contention resolution information in the random access response or in an early downlink transmission, resolving contention before the traditional msg4 exchange
4Productivity
If flexible HARQ feedback mechanisms are implemented, then resource utilization is improved, but device complexity increases
Solution Approach 1:
The system implements dynamic HARQ feedback configuration where the base station can enable or disable HARQ feedback based on real-time network conditions, UE capabilities, and service requirements. This dynamic approach optimizes resource utilization by avoiding unnecessary feedback transmissions while maintaining reliability when needed
Solution Approach 2:
The HARQ feedback mechanism is designed to serve multiple functions: it provides traditional ACK/NACK feedback when enabled, and enables power-saving operations when disabled. The same configuration framework handles both scenarios, reducing the need for separate mechanisms and minimizing overall system complexity
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A communication device, otherwise known as a user equipment (UE) may transmit a random access message (e.g., a message 3) associated with a random access procedure. A hybrid automatic repeat request (HARQ) feedback may be disabled for the random access procedure. The UE may initiate a contention resolution window associated with the random access procedure for a first downlink data channel transmission of a set of downlink data channel transmissions associated with the random access procedure. The UE may receive, during the contention resolution window, the first downlink data channel transmission carrying a contention resolution medium access control-control element (MAC-CE). The UE may transmit acknowledgment information for the first downlink data channel transmission carrying the contention resolution MAC-CE based on an indication to enable the HARQ feedback.