Non-Terrestrial Network Random Access Channel Procedure
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Solution Overview
Problem
Current wireless communication systems face challenges in supporting a large number of user equipment (UEs) simultaneously performing random access procedures, especially in non-terrestrial networks (NTNs) where larger cell sizes and higher Doppler shifts occur.
Innovation Solution
The proposed solution involves a method for random access in non-terrestrial networks, which includes using a first random access channel (RACH) procedure configured to support a larger number of UEs. This is achieved by employing Zadoff-Chu coding, additional coding procedures, and multiplexing of multiple RACH preambles in a single time and frequency resource.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a standard random access procedure is used in non-terrestrial networks, then the system can support basic UE access, but the number of UEs that can concurrently perform RACH procedure is limited
Solution Approach 1:
The RACH procedure is segmented into multiple independent coding schemes (Zadoff-Chu sequences, Gold sequences, m-sequences) that can be selectively applied to different UEs. This segmentation allows the system to handle multiple UEs concurrently by assigning different code segments to different users, thereby increasing the number of simultaneous RACH procedures while managing complexity through modular code selection.
Solution Approach 2:
The patent introduces an additional coding dimension by applying multiple coding schemes (beyond the standard single coding approach) to RACH preambles. This dimensional expansion in the code domain allows more UEs to be multiplexed in the same time-frequency resources, effectively increasing the capacity for concurrent RACH procedures without proportionally increasing system complexity.
2Quantity of substance
If additional coding procedures are applied to increase UE capacity, then more UEs can be supported, but the processing complexity increases
Solution Approach 1:
The system dynamically changes coding parameters (sequence length, code type, spreading factor) based on the number of active UEs and channel conditions. By adjusting these parameters, the system can support more UEs when needed while reducing complexity when fewer UEs are active, achieving a balance between capacity and processing load through adaptive parameter selection.
Solution Approach 2:
The patent applies coding procedures selectively rather than uniformly to all UEs. Only the necessary level of coding complexity is applied based on the specific scenario (number of UEs, channel conditions), avoiding excessive processing for cases where simpler coding suffices, thus supporting more UEs overall without proportionally increasing total system complexity.
3Productivity
If multiple RACH preambles are multiplexed in a single time and frequency resource, then resource utilization improves, but the difficulty of detecting and measuring individual preambles increases
Solution Approach 1:
Unique coding sequences act as intermediaries between multiple UEs and the base station detector. Each UE's preamble is distinguished by its specific code sequence, which mediates the separation of signals in the multiplexed transmission. The base station uses these known code sequences as reference signals to correlate and detect individual preambles amidst the multiplexed mixture, making detection feasible despite high resource utilization.
Solution Approach 2:
Different portions of the RACH procedure use different coding qualities and complexity levels. In high-density scenarios, more robust and unique coding sequences are applied locally to ensure detectability, while in lower density scenarios, simpler codes suffice. This local adaptation of code quality maintains detection performance across varying levels of preamble multiplexing density.
Data Source
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AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive information that indicates whether to perform a first random access channel (RACH) procedure for a non-terrestrial network or a second RACH procedure for a terrestrial network, wherein the first RACH procedure is configured to support a larger number of UEs contemporaneously performing a RACH procedure than the second RACH procedure. Responsive to the information indicating that the UE is to perform the first RACH procedure, the UE may perform the first RACH procedure. Numerous other aspects are provided.