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Title: Physical layer analysis of communication systems integrating antenna characteristics and propagation modelling for indoor and outdoor environments
Author: MelIios, Evangelos
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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Good antenna performance is of fundamental importance in order to ensure good wireless link quality for the high data rate demanding modern communication systems. This thesis presents a comprehensive physical layer analysis with an aim to develop and demonstrate a set of essential tools and methodologies that can be utilised in order to answer the difficult question of which antenna system can achieve the best performance in complex multi path indoor and outdoor environments. An antenna model is initially introduced, which can be integrated with a physical propagation model in order to generate a channel model suitable for system-level simulations. The model can support any antenna radiation pattern orientation and arbitrary Multiple Input Multiple Output (MIMO) array configuration in the three dimensional (3D) space. The impact of antennas on system performance is highlighted using a case-study that investigates and quantifies the effect of the interfering airborne radar antenna pattern, orientation and polarisation on Digital Terrestrial Television (DTT). It is shown that in the worst case of the scenarios that are considered 27% of the users are affected by the radar, whereas when the direction of radiation or the polarisation of the antennas are misaligned a maximum of only 3% of the users fail to receive high quality DTT signal. This study represents a detailed methodology to analyse, evaluate, and ultimately mitigate interference between co-existing communication systems. A methodology to enhance the MIMO antenna design is then presented. Using an 802.11n wireless router in an indoor residential environment, it is shown how the end to- end MIMO antenna performance of a device can be evaluated by integrating measured antenna characteristics, multipath propagation modelling and physical layer system-level simulations. The tested access point is shown to achieve an overall average performance of 145 Mbps, while a strong throughput dependence on client polarisation (average standard deviation of 32 Mbps) and terminal orientation (average standard deviation of 12 Mbps with a maximum of 39 Mbps) is demonstrated. Finally, a 3D geometry-based stochastic channel model for urban macro-cell and picocell envirolU11ents is proposed. The model is based on the statistical analysis of propagation large scale parameters, which are extracted from extensive outdoor raytracing at 800 MHz and 2.6 GHz. Key advances include statistics for elevation angular spreads (e.g. it is shown that the Root Mean Square (RMS) elevation spread at the base-station can take values up to 50° and it is 10 times larger in picocells); distance-dependent parameterisation (e.g. the RMS elevation spreads are shown to decrease significantly with distance); impact of picocell base-station height variations; and effect of user height variations on outdoor-to-indoor propagation (e.g. up to 10 dB differences in path loss are noticed due to height variations).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available