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Title: Multicell robust downlink beamforming
Author: Tshangini, Mati
ISNI:       0000 0004 5991 224X
Awarding Body: King's College London
Current Institution: King's College London (University of London)
Date of Award: 2016
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The growth in large number of users and data exchange in cellular networks, has led to an urgent improvement of the power efficiency in cellular networks. The capacity and coverage are of main concern due to the fast growing applications and demand in different areas of use. The scarcity of the traditional communications resources like time and spectrum and the safety limits on transmit power from the base stations antennas as well as the mobile terminals demand the use of new additional resources such as spatial dimensions and cooperation for the realisation of the future cellular networks. Different distributively overlaid wireless cellular network systems are being deployed to meet demand for high data rates. However, these distributively overlaid wireless cellular networks can cause higher inter-cell interference if the signals from the source antennas are not combined and coordinated. Therefore, the solution to eliminating interference is considered as the benchmark for reducing the power consumption in the network. This thesis aims to address these concerns by proposing different algorithm techniques based on beamforming for Multi-Cell Processing (MCP) addressed across multiple coordinating multi-antenna base stations. First, a distributed optimization problem in a standard semidefinite relaxation (SDR) is introduced that minimizes a combination of the sum-power, used by each base station (BS) to transmit data to its local users, and the worst-case of the resulting overall interference induced on the other users of the adjacent cells in the presence of imperfect channel state information (CSI). The aim is to ensure that the worst-cases of the signal-to-interference- plus-noise ratio (SINR) at each user remains above the required level. The feasibility solutions are achieved for certain sets of SINRs only due to relaxation of optimal beamforming. To avoid relaxation and achieve higher SINRS, a second-order cone programming (SOCP), is introduced which is solved efficiently and achieve higher SINRs. Not only for its power efficiency improvement, but, also SOCP algorithm reduces the complexity of the extra signalling overhead.
Supervisor: Aghvami, Abdol-Hamid ; Nakhai, Mohammad Reza Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available