Satellite Switching via Distributed Random Access Control
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Solution Overview
Problem
In satellite switching scenarios for non-terrestrial networks, especially in low-earth orbit satellite systems, there is a need to manage random access channel access to prevent 'random access channel storms' when multiple user equipment devices need to detach from a source satellite and access a new cell simultaneously.
Innovation Solution
The proposed solution involves a system where user equipment receives a system information block indicating a random access channel opportunity window, allowing it to determine an access time within this window and transmit a random access channel preamble at that time, thereby spreading the access across time and reducing congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If user equipment devices transmit random access channel preambles simultaneously when switching from source satellite to target satellite, then satellite switching can be completed, but random access channel storms occur causing network congestion and access failures
Solution Approach 1:
The patent introduces periodic time windows (opportunity windows) for random access channel transmission. User equipment is configured with specific time windows during which it can transmit preambles to the target satellite. By distributing access opportunities periodically across different time windows, simultaneous transmissions are avoided and network congestion is prevented while ensuring reliable satellite switching.
2Reliability
If user equipment devices are configured with dedicated radio resource control signaling for random access channel access, then access timing can be controlled, but signaling overhead increases
Solution Approach 1:
The patent enables user equipment to autonomously determine its random access channel transmission timing by receiving configuration parameters (such as opportunity window timing, preamble indices, and time offsets) through system information blocks or RRC signaling. The user equipment then independently calculates and executes transmissions without requiring continuous dedicated signaling or network coordination for each access attempt, thereby reducing signaling overhead while maintaining access control.
3Reliability
If user equipment devices monitor both source and target satellites simultaneously, then seamless switching can be achieved, but device capability requirements increase
Solution Approach 1:
The patent configures user equipment with target satellite information (including cell identity, frequency, and timing parameters) in advance through system information blocks or RRC signaling before the actual satellite switch occurs. This preliminary configuration allows user equipment to prepare for the switch without needing to continuously monitor both satellites simultaneously, reducing device complexity while ensuring seamless switching through pre-synchronized parameters.
Data Source
AI summary
A method, apparatus, and computer-program product are provided. In the context of a method, the method receives, from a first network node via a source satellite, a system information block, wherein the system information block indicates a random access channel opportunity window in which the user equipment should access the first network node or a second network node. The method includes determining, based on the system information block, an access time within the random access channel opportunity window. The method includes transmitting, to the first network node or the second network node via a target satellite, a random access channel preamble at the access time.