NBIOT frequency domain time frequency synchronization method
A technology of time-frequency synchronization and frequency domain, applied in the field of time-frequency synchronization of NB-IoT system, to achieve the effect of low mutual performance, good autocorrelation performance, and simplified operation process
Active Publication Date: 2020-04-17
HENGXIN SEMITECH CO LTD
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Problems solved by technology
If you need to capture a large frequency offset, you need to prepare several master synchronization signals with frequency offset locally for time cross-correlation. This method will consume a lot of cross-correlation calculations.
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[0057] Such as figure 1 Shown, a frequency-domain time-frequency synchronization method of NBIOT, it comprises the following steps:
[0058] S10. Receive the 1.92MHz sampling signal, perform 8 times the next sampling, and perform matched filtering with the local time-domain PSS to find the first 3 peaks and their corresponding 3 positions; specifically include:
[0059] S11, cache 1.92MHz signal r n , n=0, 1, .., 19200-1, while for r n Perform 8 times downsampling to get r m′ , m'=0, 1, ... 2400-1;
[0060] S12. Record the local PSS time domain signal as s m , m=0, 1, .., 187, r m′ and s m The result of matched filtering is denoted as q m , m=0, 1, 2400-1;
[0061] S13, from q m Find out the positions corresponding to the first 3 peaks and record them as p n , n=0,1,2.
[0062]S20. Taking the three positions as starting positions respectively, three sets of data are taken from the data of one sampling, each set of data includes 11 segments of data, each segment of d...
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The invention discloses an NBIOT frequency domain time frequency synchronization method comprising the following steps of: carrying out primary sampling, carrying out matched filtering with a local time domain PSS, and searching the first three peak values and the corresponding three positions, taking the three positions as starting positions, taking three groups of data from the primarily sampleddata, performing secondary downsampling, and performing 16-point FFT to obtain a frequency domain signal, taking five kinds of frequency domain data from the frequency domain signal according to fivedifferent subcarrier offset modes, performing cross-correlation on the five kinds of frequency domain data and a local frequency domain PSS signal to obtain cross-correlation result data, performingdelay sliding autocorrelation and weighted accumulation on the cross-correlation result data to obtain a to-be-judged result, finding the maximum value in the to-be-judged result, comparing the maximum value with a threshold, and obtaining NB-IoT synchronization information if the maximum value exceeds the threshold, and taking the peak position data exceeding the threshold, calculating the frequency offset, and completing cell time frequency synchronization. Initial synchronization can be carried out on cells in a scene with a low signal-to-noise ratio and large frequency offset in a frequency domain, and coarse synchronization and fine synchronization can be completed at one time.
Description
technical field [0001] The invention relates to the technical field of NB-IoT communication, in particular to a time-frequency synchronization method of an NB-IoT system. Background technique [0002] Narrow Band Internet of Things (NB-IoT, Narrow Band Internet of Things) is a cellular communication system with low power consumption, low cost, large capacity, and wide coverage. people's attention. [0003] The first step in NB IoT communication is the initial synchronization process, including obtaining time synchronization and frequency synchronization. The existing synchronization method uses the terminal to construct the time-domain master synchronization signal locally, and uses the correlation of the time-domain master synchronization sequence with each time point When the time point of the signal with high cross-correlation is considered to be the main synchronization, it is limited by the complexity of the implementation. Generally, in the time domain, coarse time-fr...
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IPC IPC(8): H04L27/26H04L29/08
CPCH04L27/2663H04L27/2665H04L27/2671H04L27/2672H04L67/12
Inventor 景振海李宇丁杰伟张为民周俊
Owner HENGXIN SEMITECH CO LTD