This thesis is focused on a study on modeling and measurement of the indoor radio and infrared channels. Both channels have been studied, compared and their vital differences identified. Initially, an infrared channel model was developed that was not similar to any existing models for the infrared domain. The wireless diffuse infrared channel is solely used indoors and is usually confined within a room. Conventional channel models are described, but their disadvantage is heavy time and processor requirements. A new model is introduced, in which the approach is different from the traditional methods in the way that it discretises the delay range instead of the physical characteristics of the environment. The new model offers accurate results without the increased time and processor requirements compared with traditional techniques. Following the characterisation of the infrared channel, a wideband radio propagation campaign took place in two different buildings that allowed valuable insight into the mobile radio channel. Time domain analysis of the measurement results allowed the careful study of the radio channel and produced interesting results as far as RMS delay spread and Power Delay Statistics are concerned. It has been shown that the RMS delay spread is not always dependent on antenna separation, while it was found to be highly dependent on the clutter present on the measurement environment. The infrared model was finally converted to account for radio propagation. Traditional channel models for indoor propagation prediction are described, while the major differences of the infrared and radio channel are mentioned. The radio channel prediction benefits from the accuracy of the infrared model, where a very high accuracy is necessary in order to predict the effect of scattering. A simple measurement campaign has been introduced in order to validate the results of the simulation tool and a comparison with the most important wideband channel models has been performed, along with higher frequency measurements where scattering is more important. The results present a good fit to the measurements and models in the literature, and empirical conclusions relative to the scattering characteristics of the radio channel are drawn from these comparisons.

My thesis will demonstrate that Rate Adaptive Runlength Limited encoding (RA-RLL) achieves high data rates with acceptable error rate over a wide range of signal distortion/attenuation, and background noise. RA-RLL has performance superior to other infrared modulation schemes in terms of bandwidth efficiency, duty cycle control, and synchronization frequency. Rate adaptive techniques allow for quick convergence of RA-RLL parameters to acceptable values. RA-RLL may be feasibly implemented on systems with non-ideal timing and digital synchronization.