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Title: Energy efficiency of distributed antenna systems for cellular wireless networks
Author: Serugunda, Jonathan
ISNI:       0000 0004 5917 1859
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2015
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Cellular network operators are now facing considerable challenges in terms of network capacity and a need to reduce energy consumption by rolling out energy efficient radio access networks (RANs). Use of Distributed Antenna Systems (DAS) is one feature of RAN architecture that can enhance capacity and provide ubiquitous coverage. This thesis sets out to appraise the energy savings of outdoor DAS deployments through simulations. DAS is modelled by placing Remote Radio Heads (RRHs) in a hexagonal cellular network layout and potential energy savings are evaluated using large scale propagation modelling, network equipment power consumption models and energy metrics. The conventional macro cell deployment is used as the benchmark. This research has addressed remote antell11a location, power distribution between base station and RRH and impact of user density and location on the energy efficiency gains of DAS. The results were shown to be sensitive to equipment power consumption models indicating the vital need for energy efficient equipment and backhaul in order to reap energy gains via use of DAS. The analysis shows that DAS deployments provide transmit energy savings of up to 83% over the conventional system. When the comparison is based on total operational power of the cell (including power consumed by base station, RRHs and backhaul) the energy gains depend on network equipment parameters and deployment scenarios. RRH location is found to affect DAS performance significantly since location determines if an RRH adds value in terms of throughput or suffers from inter cell interference. Further, Single Antenna Selection (S-AS) is shown to provide better energy savings than blanket transmission due to a combination of reduced transmit power and enhanced throughput. DAS is also shown to provide more energy savings in hotspot scenarios than in uniform user location cases. Energy savings can vary by +/- 22% depending upon user distribution. For a uniform user distribution, RRH placement based on shadowing knowledge can provide better performance than that based on SINR knowledge thus reducing the need for drive testing. Further, planning RRH locations to cover hotspots has been shown to provide greater energy savings and the savings increase with the number of users per hotspot. For a maximum RRH transmit power of 1W, it was observed that energy savings were 26.4% and 16.9% for S-AS and blanket transmission respectively while for the unplam1ed scenario, these values dropped to 2.9% and -5.9% respectively.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available