NTN Uplink Blind Detection for Large Time and Frequency Offsets
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Solution Overview
Problem
In non-terrestrial networks (NTN), such as those utilizing satellites, the large time and frequency offsets generated by high-speed and high-altitude satellites cannot be accurately measured by terminal devices, limiting effective communication.
Innovation Solution
A communication method where a network device performs blind detection on signals from terminal devices to determine time and frequency offsets without requiring terminal device cooperation, using specific time and frequency windows to enhance accuracy and reduce signaling overheads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If terminal device measures time offset and frequency offset based on received signal of physical channel, then measurement process is simple, but large time offset and frequency offset generated in NTN cannot be measured
Solution Approach 1:
Instead of having the terminal device measure the offset based on received signals, the network device performs blind detection on uplink signals from the terminal device to determine the offset. This inversion of the measurement direction allows the network device to handle large offsets (up to 150 kHz) that exceed terminal device capabilities, while the terminal device simply transmits without complex measurement operations.
Solution Approach 2:
The network device changes the detection parameters by performing blind detection across a range of possible time offsets and frequency offsets. By sweeping through multiple hypotheses and identifying the one that produces the strongest correlation, the system can accurately determine large offsets that would be impossible for the terminal device to measure directly.
2Measurement precision
If network device performs blind detection to determine offset information, then offset determination accuracy improves, but blind detection time and complexity increase
Solution Approach 1:
The network device performs blind detection within a pre-determined time window rather than searching the entire possible time range. This preliminary definition of the search space, based on known satellite orbital parameters and signal characteristics, significantly reduces the detection time while maintaining accurate offset determination.
Solution Approach 2:
The blind detection process is segmented into discrete time windows and frequency offset ranges. By dividing the search space into manageable segments and systematically evaluating each, the network device can efficiently determine the correct offset without exhaustive searching, reducing overall detection time while maintaining precision.
3Measurement precision
If terminal device and network device exchange signals for determining offset information, then offset measurement capability improves, but signaling overheads increase
Solution Approach 1:
The network device independently determines the offset information by performing blind detection on uplink signals from the terminal device, without requiring the terminal device to measure and report offset values. This self-service approach allows the network device to obtain accurate offset information while avoiding the signaling overhead that would result from terminal device measurements and reports.
Data Source
AI summary
This application discloses a communication method. Wherein a first network device performs blind detection on a first signal in a first beam for receiving the first signal from a terminal device, to obtain second time offset information, and determines a location of the terminal device based on the second time offset information. Then, the first network device may determine, based on the location of the terminal device, time offset information and frequency offset information that are obtained during communication between the first network device and the terminal device, to communicate with the terminal device.