Multicarrier Chirp-Division Multiplexing for RF and Underwater Acoustic Communications

Author: Song-Wen Huang  (University at Buffalo, the State University of New York) Advisor: Dimitris A. Pados

Radio frequency and underwater acoustic communications have grown rapidly in environmental monitoring, telecommunications, offshore oil exploration, and surveillance applications. Nonetheless, signals may still suffer from harsh challenges in wireless fading channels for high attenuation, multipath effect, and Doppler spread. Chirp waveforms possess characteristics to be more resilient to the above issues, so they have been utilized extensively in radar and sonar applications. However, traditional chirp signals are not orthogonal to each other and only support low data rate transmission. Therefore, there are of interests and researches to develop orthogonal chirp waveforms in high data rate transmission. The objective of this dissertation is to develop orthogonal chirp waveforms for both single carrier and multicarrier communications in radio frequency and underwater acoustic channels. Based on binary linear chirps, quasi-orthogonal chirp waveforms are designed for underwater acoustic multipath channels. In addition, M-ary orthogonal chirp modulation in coherent and non-coherent detections are proposed for underwater acoustic communications. On the other hand, orthogonal chirp waveforms are utilized as frequency subcarriers in multiuser multicarrier chirp-division multiplexing for radio frequency and underwater acoustic communications. Additionally, multiuser scenarios are adaptive in selecting parameters and strategies for enhancing performance in communication systems.

This thesis work is not only evaluated in theories and simulations, but also demonstrated its effectiveness in experiments using USRP-N210 based software-defined in-house built modems. These software-defined radio modems can provide flexibility, reconfigurability, and higher data transmission in next-generation communication networks.