NTN Random Access Timing Advance Area Segmentation
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Solution Overview
Problem
In non-terrestrial network (NTN) systems, the large distance between terminal devices and satellites results in significant signal transmission delays, making it challenging for network devices to receive preambles and determine timing advance adjustments, thereby increasing implementation complexity and reducing random access channel capacity.
Innovation Solution
The method involves terminal devices determining a target timing advance (TA) based on information associated with a synchronization signal block (SSB) received or the area where the device is located, and sending a first message in a random access procedure to the network device using this target TA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the length of the receiving window is increased to enable the network device to receive preambles from terminal devices with large distance differences, then the network device can receive preambles from all terminal devices, but the implementation complexity of the network device increases and the capacity of the random access channel is reduced
Solution Approach 1:
The cell is divided into multiple areas, and different timing advance values are assigned to different areas. This segmentation allows the network device to use multiple shorter receiving windows corresponding to different areas instead of one long receiving window, thereby reducing implementation complexity while maintaining the ability to receive preambles from all terminal devices across the entire cell coverage
Solution Approach 2:
The network device dynamically selects which receiving window to use based on the area from which the preamble is received. By making the receiving window selection dynamic and adaptive to the terminal device's location, the system achieves efficient preamble reception without requiring the network device to maintain all possible receiving windows simultaneously, thus reducing complexity
2Reliability
If the length of the receiving window is increased to accommodate large signal transmission delays, then preambles from all terminal devices can be received, but the capacity of the random access channel is reduced
Solution Approach 1:
By dividing the cell into multiple areas with different timing advance values, the system creates multiple shorter receiving windows. This segmentation allows more random access opportunities to be allocated within each area's time window, thereby increasing the overall random access channel capacity while ensuring all terminal devices can be served
Solution Approach 2:
The network device employs periodic receiving windows for different areas, allowing multiple random access occasions to be established within each period. This periodic structure increases the frequency of random access opportunities, thereby enhancing random access channel capacity without requiring an extended single receiving window
Data Source
AI summary
An access control method and a terminal device are provided, which can implement effective random access in an NTN system. The method includes: a terminal device determines a target time advance (TA) in a plurality of TAs according to first information, where the first information is associated with an SSB received by the terminal device and/or is associated with an area where the terminal device is located; and the terminal device sends a first message in a random access procedure to a network device according to the target TA.