PRACH Preamble Generation for Satellite Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In non-terrestrial networks (NTNs) with satellite communication, the large differential round-trip delays cause challenges in distinguishing user equipment (UEs) using legacy PRACH preambles due to correlation peak shifting, rendering cyclic shifts ineffective for preamble identification.
Innovation Solution
Introduce new parameters M and N for PRACH preamble formats, where M represents the number of roots and N represents the repetition number of preamble symbols, and use a fixed cyclic shift to generate preambles, allowing for a permutation-based preamble pool that distinguishes UEs based on different roots rather than cyclic shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If legacy PRACH preambles with cyclic shifts are used for random access, then the system works well in terrestrial networks with small propagation delays, but the large differential round-trip delays in satellite-based networks cause correlation peak shifting that renders cyclic shifts ineffective for preamble identification
Solution Approach 1:
The patent changes the fundamental parameters of the preamble structure by introducing multiple ZC sequence roots (different from legacy single-root approaches) and configuring specific sequence lengths and cyclic shifts adapted for satellite propagation delays. This allows the system to maintain reliable preamble identification in NTN environments where legacy parameters fail due to large differential round-trip delays causing correlation peak shifting.
2Reliability
If multiple ZC sequence roots are introduced to distinguish UEs in satellite networks, then UE identification reliability improves in NTN scenarios, but the device complexity and receiver design complexity increase
Solution Approach 1:
The patent segments the preamble identification process by dividing UEs into different groups based on their selected ZC sequence roots. Each root corresponds to a specific UE group, allowing the receiver to identify which group a UE belongs to by detecting which root's correlation peak is present. This segmentation approach simplifies receiver design compared to handling all possible roots simultaneously, as the receiver can focus on detecting specific root sequences for each detected preamble.
3Device complexity
If cyclic shifts are used for preamble differentiation in legacy systems, then the implementation is simple and device complexity is low, but the method becomes ineffective in satellite networks due to correlation peak shifting from large propagation delays
Solution Approach 1:
The patent applies preliminary action by pre-configuring specific ZC sequence roots and their corresponding cyclic shifts for different UE groups before random access occurs. The base station broadcasts the configured root indices and parameters in system information, allowing UEs to select appropriate pre-configured roots based on their group assignment. This preliminary configuration eliminates the need for dynamic cyclic shift adjustment during random access, maintaining low device complexity while ensuring reliable identification in satellite networks.
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
Methods, systems, and devices for generating preambles in mobile communication technology are described. An exemplary method for wireless communication includes transmitting, by a network node, a configuration for random access comprising a value indicative of a number of Zadoff-Chu (ZC) sequence roots (M) and a number of repetitions (N), and receiving, from a wireless device, a random access preamble, wherein the random access preamble comprises M concatenated ZC sequences with different roots, and wherein each of the M concatenated ZC sequences is repeated based on N.