Bilateral averaging over receiving and transmitting areas for accurate measurements of sector average signal strength inside buildings

In defining path loss for narrowband systems, it is common to introduce the concept of the sector or local average in order to remove the rapid (Rayleigh or Rician) fading. As originally developed for cellular mobile radio (CMR) systems, the sector average is obtained from the spatial average of the received signal as the mobile traverses a path of 20 or so wavelengths. This approach has also been applied indoors with the assumption that a unique average could be obtained by moving either end of the radio link. Unlike the CMR path for indoor propagation, however, both ends of the radio link are in a rich multipath environment. It is shown both theoretically and experimentally that moving both ends of the link is required to achieve a unique average. When averaging is accomplished by moving only one end, the result can experience variations of as much as ±2 dB when the other end is moved by a fraction of a wavelength