Shadow loss

Abstract: Radio wave propagation between base and mobile stations is normally described as being Rayleigh distributed due to multipath radio wave combining. When the number of radio wave paths are limited the variation in received signal amplitude frequently follows a more general case given by a Weibull distribution. A significant portion of the Weibull distribution is defined as the transmission loss deviation. Other definitions have been included with the object of standardizing methods of measuring and reporting propagation data. Data will be presented showing loss deviation between 3 and 30 dB. Shadow loss over hills and around buildings are usually assumed to be knife-edge or rounded knife-edge. Shadow loss based on these assumptions is generally found to be less than the true measured value. Data will be presented comparing calculated shadow loss with measured value.

Abstract: Out-of-cell interference is an important factor in determining the system capacity of CDMA systems. Out-of-cell interference is influenced by propagation parameters such as slope index s of the path loss model, the standard deviation /spl sigma/ of shadow loss, and the correlation coefficients of shadow loss for propagation to the desired base station and to the interfering base station. For line-of-sight (LOS) cells along roadways, propagation may be described by a two slope model that has smaller slow fading loss /spl sigma/ and a larger slope index past the breakpoint R/sub b/ than the single slope model. As a result, smaller out-of-cell interference is obtained with the two slope model, leading to system designs having less infrastructure than are obtained using the single slope model.

Abstract: Radio wave propagation between base and mobile stations is normally described as being Rayleigh distributed due to multipath interference. When the multipath is made up of a limited number of radio waves, the variations in signal amplitude follows a Weibull distribution. The transmission loss deviation has been defined as the dB difference between the 50 and 90% points on the Weibull distribution. Data will be presented showing loss deviation between 3 dB and 30 dB. Shadow loss over hills and around buildings are usually assumed to be knife-edge or rounded knife-edge. Shadow loss based on these assumptions is generally found to be less than the true measured value. Data will be presented comparing calculated shadow loss with measured values.

Abstract: A high performance wireless network is essential for for the railway communication and control systems. Research on the fading characteristics in railway environment is of great importance for the design of the railway wireless network. In this paper, measurements are taken in railway terrain cuttings area using track side base stations of the GSM-R network. The fitted path loss model, shadow fading, and dynamaic range of the small scale fading are obtained and compared to the results of viaduct scenario. The propagation environment of the terrain cuttings turns out to be worse than the viaduct area. The path loss exponent is found to be 4.3. The shadow loss can be reasonably described by a log-normal distribution. It is also found that the bridges over the cuttings can cause extra loss of about 5 dB. The dynamaic range of the small scale fading is from 27 dB to 40 dB with a mean value of about 33 dB.