Two-Step Random Access for High-Delay Non-Terrestrial Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing random access procedures in non-terrestrial networks (NTNs) are inefficient and face challenges in handling high propagation delays and varying signal conditions, leading to increased latency and reduced connectivity reliability.
Innovation Solution
A two-step random access procedure is introduced for NTNs, optimizing the initial access process by separating the request and response phases, thereby reducing latency and improving connectivity reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional four-step random access procedure is used in NTNs, then compatibility with existing systems is maintained, but latency is increased and connectivity reliability is reduced
Solution Approach 1:
The patent segments the traditional four-step random access procedure into a simplified two-step procedure by combining message 1 and message 3 into a single uplink transmission, and combining message 2 and message 4 into a single downlink transmission. This segmentation reduces the number of round-trip exchanges and directly addresses the latency issue while maintaining essential access functions.
Solution Approach 2:
The patent implements preliminary action by pre-configuring uplink and downlink resource allocations for the two-step random access procedure before access is needed. This allows the wireless device to immediately transmit the combined message 1/3 without waiting for dynamic resource allocation, thereby reducing latency while ensuring reliable resource availability.
2Productivity
If two-step random access procedure is implemented, then latency is reduced and connectivity reliability is improved, but system complexity increases
Solution Approach 1:
The patent merges message 1 and message 3 into a single uplink transmission, and merges message 2 and message 4 into a single downlink transmission. This combining reduces the total number of message exchanges from four to two, improving access efficiency while the merged structure actually simplifies the overall procedure flow despite the consolidation.
Solution Approach 2:
The patent introduces dynamic fallback mechanisms that allow the system to adapt between two-step and four-step procedures based on transmission success. This dynamic adaptation manages complexity by only activating additional steps when necessary, maintaining simplicity for successful cases while providing robustness when needed.
3Stability of the object's composition
If random access in NTNs handles high propagation delays, then global synchronization is maintained, but access performance deteriorates
Solution Approach 1:
The patent applies local quality by allowing different message types within the same random access procedure to have different handling characteristics. Message 1/3 combines uplink data and random access preamble with specific timing requirements, while message 2/4 provides downlink response with flexibility for late arrivals. This differentiated approach maintains synchronization requirements where needed while being tolerant of propagation delays elsewhere.
Solution Approach 2:
The patent changes timing parameters and resource allocation strategies specifically for NTN scenarios, including extended time windows for message 2/4 reception and adjusted timing advance calculations. These parameter adjustments maintain global synchronization while accommodating the high propagation delays inherent in non-terrestrial networks.
Data Source
AI summary
A wireless device selects, in response to initiating a random access procedure, a first radio resource for transmitting a message. In response to determining the first radio resource is invalid for transmission of the message, the wireless device transmits, via a second radio resource, the message based on determining the second radio resource is valid for the transmission of the message and determining a time difference between the second radio resource and the first radio resource is smaller than a threshold.