Dr. Steve Hranilovic
	M.A.Sc. Thesis

Steve Hranilovic, Modulation and Constrained Coding Techniques for Wireless Infrared Communication Channels, M.A.Sc., University of Toronto, Canada, 1999. Abstract: Short-distance, point-to-point wireless infrared optical links provide a cost-effective means of high speed data transfer between portable devices. To investigate such links, a test-bench and circuits were constructed to determine the limitations of existing optoelectronics. The results of these measurements are used to formulate a signal-space channel model which is employed for the subsequent analysis of candidate bandwidth efficient modulation schemes. The modulation scheme Adaptively Biased QAM (AB-QAM) is developed based on the channel model. AB-QAM provides an asymptotic 3~dB optical SNR improvement over PAM while maintaining the same bandwidth efficiency. The use of constellation shaping is shown to further improve the average optical power efficiency of AB-QAM. This thesis proposes the use of constrained coding techniques to satisfy the non-negativity constraint of the optical channel. These coding techniques are illustrated through an example and contrasted to a baseline case. Constrained coding techniques allow a greater flexibility in the choice of pulse shapes used in the channel, leading to possible optical power and bandwidth gains. To obtain an electronic copy of this thesis please email me at: