Implementation of a Channel Sounder for Indoor Millimetre Wave Systems at 60 GHz

Abstract

Wireless communication networks are facing new challenges as mobile data traffic grows. The currently underutilised millimetre wave spectrum is expected to be key to address these challenges. The unlicensed 60 GHz band is one of the candidate frequency bands being considered for fifth generation (5G) wireless systems, particularly for short-range (indoor) communications. The propagation characteristics at millimetre wave frequencies are largely unknown, and investigation of the indoor channel using experimental measurements are needed to effectively utilise this spectral resource. The research presented in this thesis describes a series of experiments to investigate the angular dependency of the 60 GHz channel in confined office environments. As part of this research, a 60 GHz channel sounder with a 1 GHz measurement bandwidth based on off-the-shelf components has been developed. The performance of the channel sounder was validated through comparisons to known theoretical propagation models. The experimental investigations in confined office environments demonstrate that the propagation of 60 GHz millimetre waves is dominated by the line-of-sight path between the transmit and receive antennas, and by the first- and second-order reflections from objects with smooth surfaces in the environment. Beam misalignment due to the narrow beam-widths of directional transmit and receive antennas is shown to result in increased path loss, suggesting that achieving adequate indoor coverage will be challenging without beam-steering, even in confined offices. This thesis also investigates 60 GHz propagation when the line-of-sight path between the transmitter and receiver is obstructed by the human body. In this case, first- and second- order reflections within the office are the only propagation mechanisms contributing to the received power. Inter-office measurement results between two adjacent offices demonstrate that drywall partitions are largely transparent at 60 GHz.