Wave-propagation management in indoor environments using micro-radio-repeater systems

This paper investigates the ability of micro-radio repeaters for managing wave propagation by enhancing signal coverage for the nodes of a mobile ad-hoc network in a complex environment. Such radio repeaters can be considered to be scatterers with a large radar cross section (RCS). Strategically positioning them enables a chain of line-of-sight (LoS) propagation between the transmitter and receiver when the straight signal path is blocked by obstacles such as walls. To specify repeater parameters, wave propagation in various hallway junctions were analyzed using a ray-tracing method that accounted for reflection, penetration, and diffraction. By adding the repeater model to such propagation models, the ability of micro-radio-repeater systems to enhance wave propagation in indoor environments was demonstrated. The results were verified with various measurement examples using a bench-top repeater system at 2.4 GHz. To allow multiple access through a single repeater, a simple repeater structure, composed of two omnidirectional antennas and one amplifier with sufficient gain, was considered. Measurement results indicated that in the chosen various indoor scenarios, a repeater system with an active gain of more than 35 dB with omnidirectional antennas could present scattering larger than typical building diffraction, and thus could enhance signal connectivity at 2.4 GHz.