Indoor coverage considerations for high-elevation angle systems

It is increasingly the case that users of personal communications systems expect a seamless provision of coverage, whether in rural or urban areas, outdoors or indoors. Existing 2G systems provide a fair degree of indoor coverage from existing micro- or macrocell base stations, though subscribers generally expect to have to co-operate by positioning themselves near windows. Such coverage is increasingly complemented by the addition of (public or private) picocells intended to provide connectivity over a room or a floor of a building. For conventional, terrestrial, 3G networks, this situation will be largely unchanged. The increase in frequency (110% or 10%) will result in higher building penetration losses, and the link budget may be rather more constrained, but a similar degree of indoor coverage is likely to be available. This will certainly not be the case for two types of 3G system that are currently proposed: services provided using satellites or high-altitude platforms will generally provide a high-elevation angle from receiver to transmitter, and in the case of the satellite option, a very constrained link budget. This paper examines the differences that might be anticipated between such systems in terms of the indoor coverage provided, and considers techniques by which the difficulties may be ameliorated.