Propagation models for 900 MHz cellular systems using portables and mobiles

Abstract

This paper first deals with available 900 mhz. propagation models as found in the literature. These are mean path loss estimates for street coverage in rural, suburban and urban areas. Effects of log-normal variations are taken into account in estimating total coverage around a cell site. Irregular terrain is considered by estimates of added mean loss as a function of delta H, the height between 10% and 90% of the terrain variations. Path loss estimates using discrete terrain data are next considered. Model variations providing changes in mean level that follow building density variations from urban to rural are given. Calculated values are compared to measured data taken in the Washington Baltimore area. Available map data is used to apply mixed urban and suburban models to the calculation of mean path loss to illustrate improvements in accuracy of prediction. The additional mobility of the portable relative to a mobile is taken into account by estimates of in-building losses. These losses are taken relative to outside street or sidewalk mean levels. Recent results of measurements are given in which provisions are made for both first floor doorways and for penetration into the building. Estimated margins for the two cases are given and compared to existing literature. A set of criteria suitable for subjective evaluation of portable performance is given in the form of a rating table. Results of using this rating system in the Washington Baltimore area are given for nearly 50 locations using three base sites as sources.