LTE sampling rate_weixin_39697679’s blog

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LTE sampling rate

First, the number of points in the frequency domain of the discrete Fourier transform is equal to the number of points in the time domain. Ok, go on.

At the sending end, if OFDM modulation is realized by IFFT, then the number of subcarriers needs to be extended to 2 N c 2^{N_c} 2Nc , $N_c$ is the number of subcarriers, so it will output $2^{N_c}$ points, these points need to be converted into a continuous time domain OFDM symbol by DAC. Note that this is only for a single OFDM symbol, and the baud rate of an OFDM symbol is 15k baud, so the conversion rate of the DAC needs to reach $2^N\ast 15$kHz.

At the receiving end, it is necessary to realize the conversion from the sampling sequence to the modulation symbol. In order to use the FFT algorithm to realize the efficient conversion from the sampling sequence to the modulation symbol, the number of input sampling points must satisfy $2^{N_c}$Number of subcarriers that carry modulation symbols, so the sampling rate of the receiving end needs to reach $2^{N_c}\ast 15$kHz (because one OFDM symbol requires 2 exponential sampling points as input):).

Under the 20MHz bandwidth, there are 1200 subcarriers in total, so $2^{11}$Meets the requirements, $2^{11}=2048$, so the sampling rate is 2048x15kHz = 30.72MHz.

In fact, such a high sampling rate is used to match the FFT/IFFT algorithm. In fact, if the FFT/IFFT algorithm is not used, the sampling rate can be lower. Of course, the higher the sampling rate, the smaller the signal distortion.

Reference: 4G Mobile Communication Technology Authoritative Guide LTE and LTE-Advanced Page 23

0.814108em; vertical-align: 0em;”>211=204 8, so the sampling rate is 2048x15kHz = 30.72MHz.

In fact, such a high sampling rate is used to match the FFT/IFFT algorithm. In fact, if the FFT/IFFT algorithm is not used, the sampling rate can be lower. Of course, the higher the sampling rate, the smaller the signal distortion.

Reference: 4G Mobile Communication Technology Authoritative Guide LTE and LTE-Advanced Page 23