Performance Engineering of Mobile Broadband Capacity Analysis, Cellular Network Optimization, and Design of In-Building Solutions

Abstract: The rapid evolution of mobile communication technologies is making mobile broadband a reality. With over 6 billion cellular connections and the booming of mobile data, mobile broadband leads the technology and service innovation within the domain of information and communication technologies. The thesis deals with performance engineering of mobile broadband. The problems investigated range from fundamental capacity analysis, resource planning and optimization of broadband cellular networks, to design of in-building solutions based on distributed antenna systems. Mathematical modeling and optimization methods have been used to approach the problems.The first three papers address capacity analysis in wireless communications, where the establishment of any communication link is subject to the Signal to Interference plus Noise Ratio (SINR) threshold. Paper I addresses the maximum link activation problem. The paper introduces a new exact algorithm by reformulating the SINR constraints with equivalent but numerically more effective inequalities, leading to an approach performing significantly better in proving optimality in comparison to the conventional algorithm. Paper II explores the notion of collaborative rate selection for Interference Cancellation (IC) to maximize the transmission rate in wireless networks. The paper analyzes the problem complexity and develops integer programming models for both single stage single-link IC and single stage parallel IC. Paper III studies the performance gain of single-stage and multi-stage IC to optimal link activation. Compact integer programming formulations have been developed and a thorough numerical study is performed.The next three papers are devoted to planning and optimization of radio resources in cellular mobile broadband networks. Paper IV considers a minimum-power coverage problem with overlap requirements between cell pairs. The paper develops two integer programming models and compares their strength in approaching global optimality. A tabu search algorithm has been developed for large-scale networks. Paper V deals with transmission power planning and optimization in High Speed Downlink Packet Access (HSDPA) networks. A method for enhancing the HSDPA performance by minimizing the power for coverage and reallocating the power to data transmission has been considered. A mathematical model targeting cell-edge HDSPA performance and accounting for soft handover in Universal Mobile Telecommunications System (UMTS) has been developed. In addition, heuristic algorithms based on local search and repeated local search are developed. Paper VI focuses on frequency planning for inter-cell interference mitigation in Orthogonal Frequency Division Multiple Access (OFDMA) networks. The paper generalizes the standard Fractional Frequency Reuse (FFR) concept and addresses its performance for networks with irregular topology. Optimization algorithms using local search have been proposed to find the frequency reuse pattern of generalized FFR for maximizing the edge-user performance. The investigations in Papers IV-VI base the experiments on data sets representing realistic planning scenarios to demonstrate the effectiveness of the proposed approaches.To face the challenge of in-building mobile broadband service, In-Building Distributed Antennas Systems (IB-DAS) has been proposed. Paper VII tackles the problem of optimal topology design of IB-DAS systems, where a number of in-building distributed antennas are connected to a base station via coaxial cables and power equipments. The paper develops efficient mathematical models for topology design as well as equipment selection, and presents case studies of realistic IB-DAS deployment scenarios.