5g nr sampling rate

The technical details of the 5G NR (New Radio) sampling rate.

Understanding Sampling Rate in 5G NR

The sampling rate in 5G NR is crucial for converting analog signals to digital form and vice versa. It is determined based on the maximum frequency content of the signals being transmitted or received, following the Nyquist-Shannon sampling theorem. According to this theorem, the sampling rate must be at least twice the maximum frequency component of the analog signal to avoid aliasing.

Key Parameters and Calculations

1. Subcarrier Spacing (SCS):
   • 5G NR supports multiple subcarrier spacings: 15 kHz, 30 kHz, 60 kHz, 120 kHz, 240 kHz, and 480 kHz.
   • The choice of subcarrier spacing affects the sampling rate and other physical layer parameters.
2. FFT Size:
   • The Fast Fourier Transform (FFT) size is typically 4096 for maximum bandwidth scenarios.
   • The FFT size determines the number of subcarriers and the overall bandwidth.
3. Sampling Time:
   • The sampling time is inversely proportional to the subcarrier spacing. For example, with a subcarrier spacing of 480 kHz, the sampling time is approximately 0.509 ns.
4. Symbol Duration:
   • The symbol duration varies with subcarrier spacing. For instance, at 15 kHz, the symbol duration is 66.7 µs, while at 240 kHz, it is 4.17 µs.

Example Calculation

Let’s consider an example with a subcarrier spacing of 240 kHz:

• Sampling Rate: The sampling rate can be calculated as:\text{Sampling Rate} = \text{Subcarrier Spacing} \times \text{FFT Size}For a subcarrier spacing of 240 kHz and an FFT size of 4096:\text{Sampling Rate} = 240 \times 10^3 \times 4096 = 983.04 \text{ MHz}

Practical Implications

In practical terms, the sampling rate impacts the design of the digital front-end, including the ADC (Analog-to-Digital Converter) and DAC (Digital-to-Analog Converter). Higher sampling rates require more advanced and precise hardware to handle the increased data rates and ensure signal integrity.

Conclusion

The sampling rate in 5G NR is a fundamental parameter that influences the overall performance and efficiency of the communication system. By carefully selecting subcarrier spacing and understanding the associated calculations, engineers can optimize the system for various deployment scenarios.