University of Khartoum

Investigations on the In-Band Full Duplexing Technique:The Significance of Array Geometries in Antenna Cancellation Level

Investigations on the In-Band Full Duplexing Technique:The Significance of Array Geometries in Antenna Cancellation Level

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Title: Investigations on the In-Band Full Duplexing Technique:The Significance of Array Geometries in Antenna Cancellation Level
Author: Elsanousi, Geili Tawfieg Abdalla
Abstract: This research investigated one of the In-band Full Duplexing (IBFD) techniques. IBFD is a class of enabling technologies introduced among the essential 5G featured technologies. IBFD techniques act on enabling the transceiving system to receive far field signals without separating the transmission process in any domain (frequency, time, code or spatial domains). This is attained through annihilation of looped self (transmission) signal before or within the receiver chain. IBFD has a collection of methods and algorithms over the system blocks. Antenna Cancellation Technique (ACT) is one of the early used front-end IBFD techniques. In IBFD theory progress, ACT was considered obsolete due to size, range, and bandwidth limitations whereas current IBFD antenna techniques failed to combine Multi-Element Antenna (MEA) benefits within IBFD systems. Herein, the ACT in MEA arrays was particularly investigated resulting in IBFD-oriented solutions to overcome previous ACT limitations. The research led to a strong evidence of a close relation between symmetry of antenna array geometries and the mathematical (group) symmetry entailing the differences between phases of the self looped waves. In essence, this implied that certain geometric symmetries of transmitting antenna arrays cause occurrences of antenna cancellation effect in their vicinity i.e. the presence of null points useable as IBFD receive points. To validate this, the Hexagonal Star Array (HSA) geometry was selected as a study case. In HSA geometry, the cyclic nature of waves allows this behaviour to repeat at HSA structures designed using multiples of the operating frequency (wavelengths). This implied feasible enhancements on range and bandwidth for the same IBFD points. The basic HSA was used as a seed geometry to develop Formal Multi-layered HSA (FM-HSA) which enhances range and Composite Multi-layered HSA (CM-HSA) which enhances the receive bandwidth. The HSA geometry was also usable in 2D chains and 3D connected geometries which enabled multiplicity of IBFD receive points. This was developed through directional isolation methods. This thesis followed an analytic approach complemented with empirical experimentation methods on the selected HSA geometry and its variants the FM-HSA and CM-HSA. The experimental approach focused on Computer Simulation Technology-Microwave Studio (CST-MS) as a simulation software engine and related computer simulations of the antenna radiations and the resultant electromagnetic fields. The empirical experiments conformed to the analytic inferences and validated the conclusions of this research.
URI: http://khartoumspace.uofk.edu/123456789/25555


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