Title:  Covariant Huygens Fresnel Pre-coding Matrix for Spatial Division Multiple Access

Committee:

Dr. Christopher Barnes, ECE, Chair, Advisor

Dr. Christopher Valenta, ECE, Co-Advisor

Dr. David Anderson, ECE

Dr. John Barry, ECE

Dr. Alessio Medda, GTRI

Dr. Levi Wood, ME

Abstract: With the ever-expanding demand for increased data transmission, the mobile telecommunication industry is ever in search of ways to achieve higher channel capacity and better spectral efficiency to service more users on a limited spectrum. One of the proposed solutions is Spatial Division Multiple Access (SDMA) through digital beamforming (DBF) on transmit. The objective of this dissertation is to develop a computationally efficient, near-field, location-based beamforming technique for data transmission. The CHF beamformer creates an incident wavefield at a desired location not through an angular assumption or channel inversion. Rather, the CHF beamformer’s transmitted wavefield is determined by using the covariant Huygens-Fresnel wave model of an emitter, located at the desired location of the user, which is time reversed to recreate the spatial focused incident wavefield at the emitter’s location. Due to the absence of matrix inversion, the CHF beamformer is more computationally efficient than conventional channel inversion techniques when evaluated on a per beam basis. Due to CHF’s covariant Huygens-Fresnel spherical wave model, as opposed to a directed plane wave, the CHF was designed for both near-field and far-field capabilities, unlike Fraunhofer location-based techniques. The performance of the CHF beamformer is analyzed through simulations that evaluate design parameters and tolerance to noisy environments. The simulations serve as a proof of concept of the CHF beamformer and demonstrate the performance of the CHF beamformer as a transmission technique, through the quantification of bit error rate, under different scenarios (i.e., white Gaussian noise, multiuser interference). These results demonstrated that the CHF beamformer maintains high utility, even in servicing multiple users if they are spaced according to Rayleigh distance. The impact of this new approach is highlighted at the conclusion of this dissertation by comparing current beamformers performance with the performance of the CHF beamformer.