Measured Characteristics of 800/900 MHz Fading Radio Channels with High Angle Propagation Through Moderately Dense Foliage

The probability of error for the transmission of digital information on fading radio channels is influenced by the statistical behavior of fading. This is characterized by the cumulative distribution function (CDF) for the received signal envelope, and the correlation of random variations across the channel bandwidth. It is therefore important for system design purposes to determine the distribution function for envelope fading, and the frequency correlation characteristics of radio channels in propagation environments where the use of digital radio systems is planned. This paper details experiments that were conducted under conditions similar to those which would be typical on 800/900 MHz band satellite-mobile channels in rural environments. The impulse response functions of measured channels were estimated by operating a pseudonoise channel probe from a 65 m tower through deciduous trees to a receiver at close range. Measurement results include: channel impulse response estimates, envelope fading statistics, and double-sided frequency correlation plots. Comparisons are made between channel characteristics during the summer and during the autumn after the leaves have fallen from the trees. Estimates of digital channel capacity limitations are also given. Aside from the fading statistics, these channel characteristics have not previously been reported.