Coverage Analysis and Antenna Engineering for Indoor Millimetre-Wave Communication Systems

Abstract

Sub-8 GHz wireless communication networks are experiencing significant spectral congestions as the number of personal wireless devices in the Small-Office/Home- Office (SOHO) environments exponentially increase. Fifth-generation (5G) wireless systems aim to address this problem by utilising the sparsely used millimetre-wave bands. However, coverage in SOHO environments is intermittent at these bands, owing to signals being more sensitive to shadowing and blockages. As such, this thesis investigates strategies for modelling and improving coverage for successful deployments of 5G systems in these environments. A three-dimensional coverage modelling strategy to predict shadowed regions in an office has been developed using geometrical optics, and coverage from omnidirectional antennas deployed within the office analysed. It is shown that coverage can be significantly improved without relocating the antenna if the structure can be configured to radiate signal from a less cluttered location. A tapered Leaky-Wave Antenna based on the Half-Mode Substrate Integrated Waveguide (HMSIW-LWA) that can potentially improve coverage in the office was investigated. However, it is shown that an omnidirectional HMSIW-LWA is challenging to realise at millimetre-wave frequencies. Instead, two variants of HMSIW-based antenna design with coupled printed antennas (HMSIW-CPA) that overcome these limitations are proposed. Each HMSIW-CPA variant can either couple patch antennas anywhere (CoRA) or at discrete points (DiRA) on the structure. DiRA has demonstrated the most promising performance for indoor applications, as the structure radiates 95% of the input power while maintaining a largely omnidirectional radiation pattern.