NTN Pre-Synchronization Preamble for GNSS-Independent Random Access
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Solution Overview
Problem
UEs in non-terrestrial networks (NTN) face challenges in accessing the network due to GNSS signal outages, jamming, or spoofing, leading to inaccurate time and frequency synchronization, which results in increased initial access failures and reduced connectivity reliability.
Innovation Solution
Implementing a GNSS-independent pre-synchronization mechanism that enables UEs to achieve coarse timing and frequency alignment through a preamble for synchronization, allowing for reliable initial access even in conditions where GNSS is unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UEs rely on GNSS for time and frequency synchronization in NTN, then initial access procedures can be performed, but connectivity reliability deteriorates due to GNSS signal outages, jamming, or spoofing
Solution Approach 1:
The patent introduces a pre-synchronization mechanism as an intermediary step between UE and network. The UE transmits a preamble for synchronization on a dedicated channel and receives a response message containing time and frequency correction values. This intermediary synchronization process eliminates direct dependence on GNSS, allowing UEs to achieve sufficient synchronization for random access even when GNSS is unavailable or compromised.
Solution Approach 2:
The patent implements preliminary synchronization actions before the actual random access procedure. The UE performs pre-synchronization by transmitting a synchronization preamble and receiving correction values in advance, which prepares the UE for subsequent random access messaging. This preliminary action ensures that synchronization is established through network-provided correction values rather than relying solely on GNSS at the moment of access.
2Productivity
If UEs perform synchronization without pre-synchronization in NTN, then device complexity is reduced, but initial access efficiency deteriorates due to increased access failures
Solution Approach 1:
The patent replaces the mechanical/GNSS-based synchronization system with a network-based signaling system. Instead of relying on GNSS hardware and signals, the UE uses wireless communication to exchange synchronization preambles and correction values with the network. This substitution maintains access efficiency by providing accurate synchronization through the pre-synchronization mechanism while keeping the UE architecture relatively simple.
3Reliability
If a pre-synchronization mechanism is implemented in NTN, then synchronization reliability is improved, but device complexity increases due to additional signaling procedures
Solution Approach 1:
The patent designs the pre-synchronization mechanism to serve multiple functions simultaneously. The preamble for synchronization not only establishes time and frequency alignment but also enables the network to estimate uplink timing and provides a basis for generating correction values. The response message delivers multiple types of correction information (time and frequency) in a single transmission. This multi-functionality reduces the need for separate dedicated procedures for each synchronization aspect.
Solution Approach 2:
The patent changes the approach from GNSS-dependent absolute timing to network-provided relative correction values. The network estimates timing and frequency parameters based on the received preamble and provides correction values that adjust the UE's synchronization parameters. This parameter change approach simplifies the UE's synchronization task from determining absolute time to applying relative corrections, reducing computational complexity while maintaining reliability.
Data Source
AI summary
Various aspects of the present disclosure relate to transmitting a preamble for synchronization on a resource; receiving a response message based at least in part on the transmitted preamble for synchronization, wherein the response message comprises at least one parameter for synchronization including one or more time and frequency correction values, wherein the one or more time and frequency correction values are associated with the resource, and wherein the response message is received on a channel dedicated for pre-synchronization; and transmitting one or more random access messages using the at least one parameter for synchronization including the one or more time and frequency correction values.