Spatial Spectrum Holes in TV Band: A Measurement in Beijing

Spatial spectrum holes are areas where TV signal strength falls below a certain threshold and TV frequency can be utilized without license. In our measurement, we prove the existence of spatial spectrum holes considering shadowing and building penetration. To evaluate the influence of shadowing, two dimensional radio environment mapping (REM) is constructed for a \(500\,m\,\times \,530\,m\) area in the downtown. According to the REM, a maximum attenuation of 30 dB can be caused by building blockage and shadowing. To measure the loss of wall penetration, a three dimensional measurement is conducted in the outer and inner area of a 12-floor building. It is found that the wall attenuation approximately follows a normal distribution with a mean of 24.31 dB. The distribution of spatial spectrum holes is then plotted indicating spatial spectrum holes are abundant especially in the outskirts of Beijing.