Cellular communications using aerial platforms

El-Jabu, Bashir Ali R (1999) Cellular communications using aerial platforms. University of Southampton, Doctoral Thesis.

Abstract

A cellular communications network based on aerial platforms (APs) is addressed. Each AP is located in the stratosphere and carries an adaptive antenna array whose multiple beams are able to create a carpet of contiguous cells of different sizes on the earth's surface. Under ground station control, these cells can be rapidly moved to match the network resources to the varying teletraffic load created by roaming mobile users. After reviewing the basic principles of multiple beam adaptive antenna arrays, we focus on a single AP and derive the basic system parameters; such as the area covered by an AP, the equations governing the cells formed by the beams on the earth, the signal-to-interference ratio (SIR) calculations, the size of the antenna array required to form cells of a specific size, the requisite transmitted power, and so forth.

Next, an in-depth analysis of the performance of an AP system using CDMA technology is performed for both the up-links and the down-links assuming free-space propagation. The performance is evaluated in terms of bit error rate (BER) and outage probability p₀. We show that the system can support up to 24 users per channel with p₀ < 10^-3 if the required BER < 10^-3 and the processing gain is 511.

An analysis of the effect of the positional instability of an AP on system performance is then investigated. Vertical, horizontal, and inclined movements of the AP are examined and their effect on the number of users the system is able to accommodate is quantified. The altitude and displacement errors of the position of the AP have only a minor effect on capacity. For example, altitude errors of ±0.5 km, and displacement errors of ±0.3 km results in a reduction in the number of users of between 1 and 2%. The most sensitive parameter is the inclination, and an angular error of 5^o causes the capacity to decrease by 38%. A system to control and compensate for the inclination error is proposed.

This record has no associated files available for download.

Contributors

Download statistics