2.Types of Mobile Radio Propagation

Mobile radio propagation is divided into four categories: land mobile radio, aviation mobile radio, maritime mobile radio, and satellite mobile radio. The propagation characteristics of each vary substantially depending on the type of the mobile unit and the condition of the propagation path.

In land mobile radio propagation, radio wave propagation is constantly subject to the influence of obstacles and wave reflection from objects such as buildings, trees and undulations in the terrain. Accordingly, the reception level continuously changes with movement, which can lead to instantaneous drops in the reception level of up to several dozen decibels.

The propagation paths in the aviation and maritime mobile radio propagation contain virtually no obstacles and so are almost equivalent to free space paths. However, because propagation paths can be bent depending on the weather conditions, the air refraction ratio and the earth's spherical shape must be considered when estimating the propagation characteristics.

In case of satellite mobile radio propagation, most of the propagation path lies outside the atmosphere. Despite the substantial propagation loss, the fact that almost no obstacles are encountered means that stable electric field strength can be achieved along the line of sight. However, satellite propagation is still affected by surface reflection from the sea and the shielding impact of buildings, etc., on land.

Radio wave propagation characteristics		Fading mode	Factor	Principle entities
Instantaneous value fluctuation	Envelope curve fading (Rayleigh distribution)	Non-optional	Multiple wave interference	Median point over short intervals
	Random FM noise	Time option	Doppler shift	Maximum Doppler frequency
	Dispersion of delay	Frequency option	Corridor difference	Delay
Location characteristics (Normal logarithmic fluctuation)		Non-optional	Topography and structures surrounding a mobile unit	Median point and standard deviation over an extended interval
Distance characteristics (Okumura's propagation curve)		Non-optional	Propagation profile	Base station-mobile station antenna height, distance between stations, wireless frequency

Radio wave propagation characteristics in terrestrial mobile communications

Radio wave propagation characteristics and factors in terrestrial mobile communications

Created 1999/03