NB-IoT Uplink Synchronization Timing Deviation Determination
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Solution Overview
Problem
The NB-IoT system experiences lower accuracy in determining uplink synchronization timing deviation due to the lack of distinct peaks after FFT and IDFT transformations, which affects the precision of uplink synchronization.
Innovation Solution
The base station determines the channel estimate value for each symbol group in the preamble signal and performs conjugate multiplication based on the frequency hopping pattern to obtain a radian value, reflecting the phase difference and thereby improving the accuracy of uplink synchronization timing deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If FFT and IDFT transformations are performed on the NB-IoT preamble sequence, then the processing method is compatible with LTE system, but the peak in the detection window becomes not obvious and determination accuracy decreases
Solution Approach 1:
The patent segments the NB-IoT preamble sequence into four symbol groups, each containing one CP symbol and five OFDM symbols. By processing each symbol group separately and performing conjugate multiplication between corresponding symbols in different groups, the method extracts phase difference information that reflects timing deviation, thereby resolving the contradiction between LTE compatibility and determination accuracy.
2Ease of manufacture
If the same signal is transmitted on five OFDM symbols in each symbol group, then the NB-IoT preamble structure is simplified, but the peak presented after FFT and IDFT is not obvious
Solution Approach 1:
The patent introduces phase difference as an intermediary parameter to indirectly reflect timing deviation. Instead of directly detecting the peak from FFT and IDFT transformations, the method uses conjugate multiplication to extract phase difference information from corresponding symbols in different symbol groups, which serves as a mediator to achieve accurate timing deviation determination despite the simplified preamble structure.
Data Source
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AI summary
Disclosed in the present disclosure are an uplink synchronization timing deviation determination method and device, for solving the problem in the prior art that a base station in an NB-IoT system has low accuracy in determining an uplink synchronization timing deviation by performing FFT and IDFT processing on a preamble sequence. The method specifically comprises: a base station receiving a preamble signal transmitted by a terminal device; determining channel estimation values of a frequency domain channel occupied for transmitting each symbol group of the preamble signal; performing, on the basis of a frequency hopping pattern used for transmitting the preamble signal, a conjugate multiplication on the channel estimation values corresponding to each symbol group to obtain a first radian value, and determining, on the basis of the first radian value, an uplink synchronization timing deviation of the terminal device.