Spectrum Occupancy Evaluation with RTL-SDR (H)
Personal Final Year Project | Sept.2018 - Mar.2019
Overview
CR (cognitive radio) is viewed as the most promising technologies to the problem of spectrum congestion. In order to realize the CR network, an essential step is to first survey the current spectrum occupancy in terms of frequency, time and geographical area and with reference to spectrum allocation regulations.
In this project, a measurement campaign is performed to characterize spectrum occupation in the frequency range up to 2 GHz in certain locations concerning outdoor and indoor scenarios in Liverpool, UK.
An RTL-SDR (Software Define Radio) USB device and a laptop with MATLAB Simulink software were used to collect, process and analyse signal information.
Lead the project which studies the spectrum occupation with extensive field measurements in the frequency range up to 2 GHz in certain places in Liverpool
Determine the current spectrum usage status and identify the underutilized frequency bands that can be used for opportunistic use.
Use an RTL-SDR hardware device receives signals in the air and then processes signals by MATLAB and Simulink software control
Analyze the measurement results via MATLAB system toolbox to visually obtain the power spectrum density (PSD) vs frequency in certain frequency ranges and consequently evaluate spectrum usage in current measurement location
Methodology
Figure 1. Spectrum Occupancy Evaluation Theory: Energy Detect Method | Occupancy Metric | Evaluation Metric
Energy detection
Power spectrum density (PSD)
The decision threshold
Duty cycle
Figure 2. Generation of PSD by the FFT
Measurement Setup
Figure 3. RTL2832U RTL-SDR USB Device
Figure 4. Signal Processing by RTL-SDR USB Device
Figure 5. Measurement Sites (Courtesy of Google Inc.)
Results
The amount of allocated frequencies below 2 GHz are underutilized in Liverpool.
Most of the frequency bands above 1 GHz are almost idle and suitable for cognitive radio applications.
Moreover, the surrounding environment of measurement sites and the predefined threshold have significant impacts on measurements.
