Satellite Random Access Resource Selection for GNSS-Free Terminals
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Solution Overview
Problem
Terminal devices without GNSS capability face challenges in accessing satellites due to high mobility and frequency offsets, leading to inter-carrier interference and reduced success rates in satellite communication, especially in IoT applications.
Innovation Solution
Configuring multiple groups of random access resources with varying subcarrier spacings and positions to enable terminal devices to select appropriate resources based on their GNSS capability or preamble type, reducing interference and correcting frequency offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If terminal devices without GNSS capability attempt to access satellites using conventional single-group random access resources, then device cost is reduced, but frequency offset causes inter-carrier interference and access success rate deteriorates
Solution Approach 1:
The random access resources are segmented into multiple groups (first group and second group) with different subcarrier spacings. Terminal devices without GNSS capability can select the first group with larger subcarrier spacing to resist frequency offsets, while devices with GNSS capability can use the second group with smaller subcarrier spacing for higher access success rate. This segmentation allows cost-effective devices to access satellites without requiring GNSS hardware.
Solution Approach 2:
The patent changes the subcarrier spacing parameter of random access resources to address frequency offset issues. The first group uses a first subcarrier spacing while the second group uses a second subcarrier spacing that is smaller than the first. By adjusting this parameter, the system enables devices without GNSS to tolerate larger frequency offsets and successfully access satellites.
2Reliability
If multiple groups of random access resources with different subcarrier spacings are configured, then access success rate for devices without GNSS is improved, but system complexity increases
Solution Approach 1:
The system dynamically adapts the random access resource configuration based on terminal device capabilities. Terminal devices without GNSS capability are directed to use the first group of random access resources with larger subcarrier spacing, while devices with GNSS capability use the second group with smaller subcarrier spacing. This dynamic adaptation allows the system to maintain high access success rates for diverse devices without requiring complex processing at the terminal side.
Solution Approach 2:
The patent creates a universal random access mechanism that serves both devices with and without GNSS capability through a unified multi-group resource configuration. The network device configures multiple groups of random access resources that can be universally used by different types of terminal devices, with each device selecting the appropriate group based on its capability. This universal approach simplifies the overall system architecture compared to designing separate access mechanisms for different device types.
Data Source
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AI summary
A communication method and apparatus are provided, to enable various terminal devices to successfully access a satellite. A terminal device receives, from a network device, configuration information that indicates at least two groups of random access resources, where any group of random access resources includes a plurality of subcarriers in frequency domain, and subcarrier spacings included in the at least two groups of random access resources in frequency domain are different. The terminal device selects one group of random access resources from the at least two groups of random access resources based on first information, and sends a random access preamble to the network device based on the selected group of random access resources. The first information is information indicating whether the terminal device supports a GNSS capability, or is a random access preamble type selected by the terminal device. A plurality of groups of random access resources with different subcarrier spacings in frequency domain are configured to respectively resist different frequency offsets, so that the terminal device can select an appropriate random access resource depending on whether the terminal device supports the GNSS capability or based on the selected random access preamble type or the like, to access a satellite.