Geometric frequency reuse for irregular cellular networks

PhD ThesisThis thesis uniquely addresses challenges of bandwidth management in cellular networks. The need for enhanced frequency assignment strategies in Long term evolution (LTE) systems arises due to the limiting e ects of intercell interference (ICI). In this study, the realistic scenario of irregular network coverage patterns is considered, and in addition, Heterogeneous cellular networks (HetNets). Firstly, extensive analysis using simulations is presented for static frequency reuse (FR) techniques in irregular Homogeneous (single-tier) cellular networks. Investigation was carried out over several network positional and deployment layouts. Second, a model is developed for irregular networks by de ning frameworks for their location parameters and relationships, FR bandwidth and power assignment, and the probability of interference in partitioned FR schemes. A novel Geometric FR (GeoFRe) algorithm is then proposed for single-tier networks with random BS placements. Third, an optimization framework based on user fairness is proposed and implemented for single-tier networks based on the concept of virtual UEs in di erent BS regions. Finally, a framework for HetNets is presented where macro and small BS deployments have imperfect coverage grid patterns. Performance analysis is then carried out for two implementations of the Soft FR (SFR) algorithm. Results from this research provide detailed analysis on impact of BS irregularity on UE performance under FR schemes, a simpli ed framework for modelling irregular macro BS, an improved FR model, accurate computations for the area of irregular network coverage patterns for intelligent bandwidth assignment, an optimization framework to improve user fairness (and edge UE performance) in single-tier networks and an FR model with performance analysis for irregular Het- Nets.National Information Technology Development Agency (NITDA) and Federal University of Technology Minna, both in Nigeria for o ering me scholarship and support

Design and implementation of an intelligent system for detecting drowsy drivers.

This paper presents a drowsy driver detection system, designed using an AT89C52 microcontroller in combination with smart sensors. Drowsy driving has been discovered to be a major cause of road traffic collisions. The problem lies in the fact that a driver is usually unaware of the on-set of drowsiness. It therefore becomes necessary to design an intelligent system that will know when a driver is getting drowsy and alert him. Before the electronic system was designed, tests were carried out to study driver behaviors for different sex and age categories. The response time to deviation and other important parameters were measured over a 45-minute driving test period and results obtained have been presented. The system developed is a hybrid system, motivated by Mercedes-Benz’s drowsy detection system. It is composed of the power supply unit, sensing unit, speedometer, microcontroller unit and driver interface unit. It works based on observations of a driver’s behavior at the start of every trip. Initial individual driver’s profiles are created and continuously compared with subsequent sensory data obtained during the course of the trip. The monitoring performed detects transition between being awake and drowsiness and warns the driver early enough. The system presented is simple, easily fits into different vehicles, unobtrusive and well suited for the cost implications in Nigeria.Keywords: Microcontroller-based devices, intelligent systems, Drowsy driver detectionNigerian Journal of Technological Researc