PRACH Configuration Selection for Non-Terrestrial Network Access
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Solution Overview
Problem
Existing network access methods for non-terrestrial networks face challenges in resource ambiguity during initial access procedures, particularly due to long round-trip times and Doppler shifts, which can lead to incorrect identification of PRACH occasions and resources.
Innovation Solution
The proposed solution involves a WTRU selecting a PRACH configuration and preamble group based on timing advance (TA) information and synchronization signal blocks (SSBs), and transmitting multiple preambles before receiving a random-access response to mitigate resource ambiguity and improve access reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional network access methods are used in non-terrestrial networks, then the initial access procedure is simple, but resource ambiguity occurs due to long round-trip times and Doppler shifts leading to incorrect PRACH occasion identification
Solution Approach 1:
The patent segments the PRACH configuration selection process by dividing SSBs into groups and assigning different preamble groups to different SSB groups. This segmentation allows the WTRU to select preambles based on specific SSB characteristics, reducing ambiguity in PRACH resource identification while maintaining manageable complexity through structured organization of the selection criteria.
Solution Approach 2:
The patent applies preliminary action by having the WTRU select and prepare the appropriate preamble and PRACH configuration before the actual random access transmission. The WTRU determines the preamble group and specific preamble based on detected SSB characteristics in advance, ensuring that the correct resources are ready for transmission and avoiding resource ambiguity during the critical access phase.
2Reliability
If multiple preambles are transmitted before receiving random-access response, then resource ambiguity is reduced and access reliability is enhanced, but transmission time and network processing delay increase
Solution Approach 1:
The patent enables preliminary action by allowing the WTRU to transmit multiple preambles in advance based on predicted path loss and selected preamble groups before receiving the random-access response. This preliminary transmission of multiple preambles ensures that at least one will be correctly received and processed, reducing access failures while the network can efficiently process these pre-transmitted preambles using the established timing advance information.
Solution Approach 2:
The patent utilizes feedback mechanisms where the network provides timing advance information and path loss predictions to the WTRU. The WTRU uses this feedback to select appropriate preambles and adjust transmission parameters, enabling more efficient multiple preamble transmissions that reduce overall access time while maintaining high reliability through informed preamble selection based on network-provided feedback data.
3Productivity
If transmit power is adjusted based on predicted path loss, then access efficiency is improved, but accuracy of path loss prediction is required which increases processing complexity
Solution Approach 1:
The patent applies preliminary action by having the network provide path loss predictions to the WTRU in advance before the random access transmission. The WTRU uses these pre-provided predictions to select appropriate preambles and set transmit power levels, eliminating the need for complex real-time path loss calculation while still achieving efficient power adjustment based on predicted propagation conditions.
Solution Approach 2:
The patent uses path loss prediction information as an intermediary element that bridges the network's knowledge of propagation conditions and the WTRU's transmission decisions. Instead of requiring the WTRU to independently calculate complex path loss values, the network provides this prediction data as an intermediary that simplifies the WTRU's processing while enabling efficient transmit power adjustment based on actual propagation environment characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the ambiguity in PRACH resource selection, enhances the reliability of initial access procedures in non-terrestrial networks, and minimizes delays by allowing the WTRU to adjust its transmit power based on predicted path loss.
Implementation Method 1
a first message is transmitted from the wireless transmit/receive unit to the network through a first air interface
Implementation Method 2
Existing network access methods for non-terrestrial networks face challenges in resource ambiguity during initial access procedures, particularly due to long round-trip times and Doppler shifts
Data Source
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Figure 1B
Figure 1C
AI summary
Methods, apparatuses, systems, etc. for, and/or for use in connection with, performing network access and/or other procedures in a non-terrestrial network (NTN) of a communications system. Among the methods are methods that may be implemented in a wireless transmit/receive unit (WTRU) and may include any of receiving, from the NTN, differential delay information and physical random access channel (PRACH) configuration information indicating a set of preambles and a PRACH occasions configuration; determining a set of candidate PRACH occasions, from among a plurality of PRACH occasions of the PRACH occasion configuration, based on the differential delay information; selecting a preamble from a group of the preambles allocated to one candidate PRACH occasion of the set of candidate PRACH occasions; and transmitting the selected preamble using a PRACH resource corresponding to the one candidate PRACH occasion.