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Energy Efficiency of Heterogeneous LTE Networks
KTH, School of Electrical Engineering (EES), Communication Theory.
2015 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Awareness of climate change and our environment is affecting the field of mobile communications. The challenge of reducing the carbon footprint and operating expenditures, while the demand for coverage and capacity is growing exponen-tially, is driving the trend of studying energy efficiency of mobile networks. Providing services in a resource efficient way have benefits both for the operator and the environment, which is why requirements on energy performance will be a part of the specifications of future 5G networks. In long term evolution (LTE) networks, indoor small cells are deployed inlarge volume to improve performance in areas with poor macro coverage or high traffic demand. This type of network topology, that consists of several types of access nodes, is called a heterogeneous network (HetNet). In this master thesis we study the energy efficiency of various HetNet deployments in a dense urban environment. The small cells deployments investigated are pico base stations and micro distributed antenna systems. Dense and sparse deployment strategies with varying transmit powers are compared. Furthermore, we investigate the potential for energy savings by setting the small cells into a low power sleep state under certain conditions. Both short sleep periods between transmissions, called discontineous transmission (DTX), and longer sleep cycles during periods of low activity is investigated.This thesis was carried out as a project at Ericsson Systems & Technology in Kista, Stockholm 2015. To be able to evaluate the energy consumption at network level, realistic models for the power consumption of various base station types had to be implemented into a static radio network simulator. Results show good performance of the considered HetNets but at a cost ofhigher power consumption than a macro only network. For example, a pico HetNet with twice the macro capacity consume 75% more energy over one day. However, results show that with DTX and sleep modes enabled, the daily energy consumption of the same HetNets is only 30% higher than the macro only network. Therefore, the main conclusion is that energy saving techniques will be of great importance for improving capacity without increasing network energyconsumption.

Abstract [sv]

Medvetenhet om klimatförändringar i vår miljö påverkar även utvecklingen avmobila kommunikationssystem. Att minska utsläppen av CO2 från kommu-nikationsindustrin samt minska operatörernas kostnader samtidigt som kravenpå nätverkens kapacitet och täckning ökar är en utmaning. Denna utmaningdriver en ny trend att studera energi-effektivitet i mobila nätverk. Att levereratjänster på ett resurs-effektivt sätt är likväl lönsamt för operatörerna som förvår miljö. Detta är en anledning till att tydliga krav på nätverkens energiför-brukning nyligen har lagts till på listan över krav på framtida 5G nätverk. Bas-stationer med låg uteffekt, så kallade “small cells", är vanligt förekommande idagens Long Term Evolution (LTE) nätverk. De placeras ut i områden medantingen dålig täckning eller höga krav på data trafik. Sådana nätverk, sombestår av flera typer av access-noder, kallas för heterogena nätverk. I dettaprojekt studeras energi-effektiviteten av heterogena LTE nätverk i tätbebyggdstadsmiljö. Access-noderna som studeras är så kallade Pico-noder samt olika“distributed-antenna -system". Flera olika nätverks-topplogier undersöks samthur förändringar i access-nodernas ut-effekt påverkar energi-effektiviteten. Vi-dare studeras möjligheterna att spara energi genom att under vissa förutsät-tningar köra bas-stationer i ett läge av låg effektförbrukning. Dessa perioder kanvariera i storleksordningen av en mikrosekund varvid det kallas “discontineoustransmission", ända upp till flera timmar. De olika metoderna utvärderas medhjälp av ett statiskt simulerings-program för LTE nätverk. För att utvärderaenergiförbrukning har realistiska modeller för bas-stationernas effektförbrukningimplementerats i simulerings-programmet.

Place, publisher, year, edition, pages
2015. , 57 p.
Series
EES Examensarbete / Master Thesis, XR-EE-KT 2015:007
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:kth:diva-169910OAI: oai:DiVA.org:kth-169910DiVA: diva2:826087
Educational program
Master of Science - Wireless Systems
Presentation
2015-05-25, SIP conference room, Osquldas väg 10, Floor 3, Stockholm, 15:54 (English)
Supervisors
Examiners
Available from: 2015-11-03 Created: 2015-06-24 Last updated: 2015-11-03Bibliographically approved

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