Path Loss Modeling of WLAN and WiMAX Systems

With the advancement in technology, there was need for efficient and high speed internet through which we could have access to multiple networks as per the user requirement. WLAN met this need to some extent but, due to its low range it was not recommended commercially. With the introduction of WiMAX there was an emerging need to select the best network amongst WiMAX or WLAN depending upon the user location. Pathloss with respect to these particular networks also needs to be compared. In this paper we compare the pathloss modelling for WiMAX and WLAN systems. Different Models have been compared with each other to know which model performs better by keeping same simulation environment. Path Loss models used for WLAN are Okumura, Hata, Cost-231 and Free Space Path Loss whereas models used for WiMAX are Free Space Path Loss, Okumura-Hata, Cost231-Hata and Stanford University Interim. In case of WiMAX three different scenarios Urban, Sub-Urban and Rural is considered where as in case of WLAN only outdoor environment is considered. With the Path Loss comparison, power received for these two technologies; WiMAX, and WLAN is also simulated. MATLAB is the tool used for simulations. Antenna Specifications for WiMAX and WLAN is kept same for all simulation environments

Maximising spectral efficiency in LTE cells

The efficiency with which spectrum is used in wireless communications systems is becoming increasingly important as a result of the expected growth in traffic demand and the finite nature of usable spectrum. Spectral efficiency, defined as throughput divided by bandwidth, is a useful metric for evaluating the use of spectrum in wireless systems. In any given area the achievable spectrum efficiency is impacted by the underlying user population. This paper presents the methodology for finding the transmit power which maximises the spectral efficiency of a LTE cell for a given user density and traffic type. The impact of different user densities and traffic profiles on the choice of transmit power is evaluated. Results show that the transmit power which maximise spectral efficiency decreases as the user density and average data rate of the traffic profile increases. Two non ideal real world scenarios which require an increase in cell spectral efficiency are also considered and a modified user admission scheme which can increase the cell spectral efficiency is presented and evaluated. Results showed that the spectral efficiency was improved but the maximum improvement depended on the traffic profile and practical constraints of the LTE standard

PERFORMANCE INVESTIGATION OF WIRELESS INTEGRATED NETWORKS FOR RURAL AREA

Abstract: Wireless technology having an important role in the field of communications and allows users to connect at anywhere and anytime. The users enjoy the features of 3G networks such as more connectivity and IEEE 802.11 Wireless LAN has its own advantages in terms of low cost and its widespread use. In order to get the best services of both technologies, the idea of integrating UMTS with Wireless Local Area Network (WLAN) came into existence. The integrated UMTS-WLAN network can be capable of providing ubiquitous connectivity and high data rate to the end user. The work in this paper presets the performance of the wireless integrated network for the rural environment. The combined effect of the packet loss and mobility has been analyzed for the wireless integrated networks. The proposed architecture analyzes the performance of integrated UMTS-WLAN with outdoor to indoor and pedestrian path loss model for the rural environment under varying network conditions

Optimisation of a propagation model for last mile connectivity with low altitude platforms using machine learning

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonOur related research review on propagation models reveals six factors that are significant in last mile connectivity via LAP: path loss, elevation angle, LAP altitude, coverage area, power consumption, operation frequency, interference, and antenna type. These factors can help with monitoring system performance, network planning, coverage footprint, receivers’ line-of-sight, quality of service requirements, and data rates which may all vary in response to geomorphology characteristics. Several competing propagation models have been proposed over the years but whilst they collectively raise many shortcomings such as limited altitude up to few tens of meters, lack of cover across different environments, low perdition accuracy they also exhibit several advantages. Four propagation models, which are representatives of their types, have been selected since they exhibit advantages in relation to high altitude, wide coverage range, adaption across different terrains. In addition, all four have been extensively deployed in the past and as a result their correction factors have evolved over the years to yield extremely accurate results which makes the development and evaluation aspects of this research very precise. The four models are: ITU-R P.529-3, Okumura, Hata-Davidson, and ATG. The aim of this doctoral research is to design a new propagation model for last-mile connectivity using LAPs technology as an alternative to aerial base station that includes all six factors but does not exhibit any of the shortcomings of existing models. The new propagation model evolves from existing models using machine learning. The four models are first adapted to include the elevation angle alongside the multiple-input multiple-output diversity gain, our first novelty in propagation modelling. The four adapted models are then used as input in a Neural Network framework and their parameters are clustered in a Self-Organizing-Map using a minimax technique. The framework evolves an optimal propagation model that represents the main research contribution of this research. The optimal propagation model is deployed in two proof-of-concept applications, a wireless sensor network, and a cellular structure. The performance of the optimal model is evaluated and then validated against that of the four adapted models first in relation to predictions reported in the literature and then in the context of the two proof-of-concept applications. The predictions of the optimised model are significantly improved in comparison to those of the four adapted propagation models. Each of the two proof-of-concept applications also represent a research novelty.The Royal Saudi Embassy and the Saudi Cultural Bureau in London, and Taif University in the Kingdom of Saudi Arabia