Broadband indoor wireless communications using infrared.

Abstract

In this thesis, we discuss the issue of using infrared light as a carrier for broadband indoor wireless networks. We discuss the infrared channel and show how it differs from conventional radio frequency channel. Noise sources for this environment and the practical ways of reducing their harmful effects are discussed. We determine the safety levels for the radiated power of an IR transmitter and we show how the system should be designed to operate within the safety limits. We introduce a computer-simulation algorithm to find the impulse response of an indoor infrared channel and discuss several implementation issues for the algorithm. Using the simulation software, we investigate temporal and spatial distributions of the channel, e.g., the delay spread of impulse response and the total received optical power. We use the results of the simulations to investigate the effects of receiver rotation on the channel properties. We propose an angular diversity as a mean for performance improvement in an infrared receiver. Simulating the noise sources and signal sources in a typical indoor environment, we see how diversity improves the signal-to-noise ratio in a receiver with the angular diversity reception.