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On the Design of Energy Efficient Wireless Access Networks
KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.ORCID iD: 0000-0002-5016-5044
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Wireless access networks today consume 0.5 percent of the global energy. Rapidly growing demand for new services and ubiqutious connectivity, will further increase the energy consumption. This situation imposes a big challenge for mobile operators not only due to soaring cost of energy, but also increasing concern for global warming and sustainable development.

This thesis focuses on the energy efficiency issue at the system level and studies how to incorporate energy-awareness into the design of future wireless access networks. The main contributions have been given in the areas of energy efficiency assessment, architectural and operational solutions, and total cost of investment analysis.

The precise evaluation of energy efficiency is the first essential step to determine optimized solutions where metrics and models constitute the two key elements.We show that maximizing energy efficiency is not always equivalent to minimizing energy consumption which is one of the main reasons behind the presented contradictory and disputable conclusions in the literature. Further we indicate that in order to avoid the debatable directions, energy efficient network design problems should be formulated with well defined coverage and capacity requirements. Moreover, we propose novel backhaul power consumption models considering various technology and architectural options relevant for urban and rural environments and show that backhaul will potentially become a bottleneck in future ultra-high capacity wireless access networks.

Second, we focus on clean-slate network deployment solutions satisfying different quality of service requirements in a more energy efficient manner. We identify that the ratio between idle- and transmit power dependent power consumption of a base station as well as the network capacity requirement are the two key parameters that affect the energy-optimum design.While results show that macro cellular systems are the most energy efficient solution for moderate average traffic density, Hetnet solutions prevail homogeneous deployment due to their ability to increase the capacity with a relatively lower energy consumption and thus enable significant energy savings in medium and high capacity demand regions.

Moreover, we investigate the energy saving potential of short-term energy aware management approach, i.e., cell DTX, taking advantage of low resource utilization in the current networks arising from strict QoS requirements. With the help of developed novel quantitative method, we show that Cell DTX brings striking reduction in energy consumption and further savings are achievable if the networks are designed taking into account the fact that network deployment and operation are closely related.

Finally, we develop a general framework for investigating the main cost elements and for evaluating the viability of energy efficient solutions.We first reveal the strong positive impact of spectrum on both energy and infrastructure cost and further indicate that applying sustainable solutions might also bring total cost reduction, but the viability highly depends on unit cost values as well as the indirect cost benefits of energy efficiency.

Results obtained in this dissertation might provide guidelines for the network designers to achieve future high-capacity and sustainable wireless access networks.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology , 2014. , xi, 58 p.
Series
TRITA-ICT-COS, ISSN 1653-6347 ; 1403
Keyword [en]
Energy Efficiency, Wireless Access Networks, Backhaul, Network Deployment, Power Consumption Model, Cell DTX, Cost Analysis
National Category
Communication Systems
Research subject
Information and Communication Technology
Identifiers
URN: urn:nbn:se:kth:diva-144868OAI: oai:DiVA.org:kth-144868DiVA: diva2:714913
Public defence
2014-05-23, Sal D, Forum, KTH, Isafjordsgatan 39, Kista, 13:00 (English)
Opponent
Supervisors
Note

QC 20140505

Available from: 2014-05-05 Created: 2014-04-29 Last updated: 2014-05-26Bibliographically approved
List of papers
1. On Metrics and Models for Energy Efficiency in Wireless Access Networks
Open this publication in new window or tab >>On Metrics and Models for Energy Efficiency in Wireless Access Networks
(English)Manuscript (preprint) (Other academic)
Identifiers
urn:nbn:se:kth:diva-144991 (URN)
Note

QS 2014

Available from: 2014-05-05 Created: 2014-05-05 Last updated: 2014-05-08Bibliographically approved
2. Impact of backhauling power consumption on the deployment of heterogeneous mobile networks
Open this publication in new window or tab >>Impact of backhauling power consumption on the deployment of heterogeneous mobile networks
Show others...
2011 (English)In: 2011 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE (GLOBECOM 2011), 2011, 6133999- p.Conference paper, Published paper (Refereed)
Abstract [en]

Energy efficiency in cellular mobile radio networks has recently gained great interest in the research community. The development of more energy efficient hardware and software components aside, effect of different deployment strategies on energy efficiency are also studied in the literature. The latter mainly consist of optimizing the number and the location of different types of base stations in order to minimize the total power consumption. Usually, in the literature, the total network power consumption is restricted to the sum of the power consumption of all base stations. However, the choice of a specific deployment also affects the exact implementation of the backhaul network, and consequently its power consumption, which should therefore be taken into account when devising energy efficient deployment. In this paper, we propose a new power consumption model for a mobile radio network considering backhaul. We then handle a case study and perform a comparison of the power consumption of three different heterogeneous network deployments, and show how backhaul has a non-negligible impact on total power consumption, which differs for different deployments. An energy efficiency analysis is also carried out for different area throughput targets.

Series
IEEE Global Telecommunications Conference (Globecom), ISSN 1930-529X
Keyword
Power Consumption Model, Heterogeneous Networks, Energy Efficiency, Backhaul, Network Deployment
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-92083 (URN)000300509002127 ()2-s2.0-84863142017 (Scopus ID)978-1-4244-9268-8 (ISBN)
Conference
54th Annual IEEE Global Telecommunications Conference (GLOBECOM) DEC 05-09, 2011 Houston, TX
Projects
Energy-efficient wireless networking (eWIN)
Funder
ICT - The Next GenerationWireless@kth
Note

QC 20120326

Available from: 2012-03-26 Created: 2012-03-26 Last updated: 2016-04-22Bibliographically approved
3. Mobile backhaul in heterogeneous network deployments: Technology options and power consumption
Open this publication in new window or tab >>Mobile backhaul in heterogeneous network deployments: Technology options and power consumption
2012 (English)In: 14th International Conference on Transparent Optical Networks, 2012, 1-7 p.Conference paper, Oral presentation only (Refereed)
Abstract [en]

Mobile communication networks account for 0.5% of the global energy consumption, a value that is expected to double within the next five years. For this reason, means of reducing the energy consumption in cellular mobile radio networks has recently gained great interest within the research community. In mobile networks the backhaul contribution to the total power consumption is usually neglected because of its limited impact compared to that of the radio base stations. However, meeting the almost exponential increase in mobile data traffic requires a large number of (mainly small) base stations. This means that backhaul networks will take a significant share of the cost and the energy consumption in future systems. Their actual contribution to the energy consumption will depend on the radio base station deployment scenario as well as on the technology and topology choices for the backhaul itself. This paper presents an initial assessment of the power consumption of two established backhaul technologies, i.e., fiber and microwave. For the microwave case, three backhaul topologies are considered, i.e., tree, ring and star, while for the fiber case only one topology is analysed, i.e., a dedicated point-to-point star. The presented results, assuming off-the-shelf products and based on todays network capacity levels, confirm the importance of considering the backhaul when minimizing the total power consumption in heterogeneous network scenarios. They also show the impact of the basic technology and topology choices of the backhaul for minimizing total power consumption.

Keyword
Green networks, fiber-based backhaul, heterogeneous wireless networks, microwave-based backhaul, mobile backhaul, pico base stations
National Category
Communication Systems
Research subject
SRA - ICT
Identifiers
urn:nbn:se:kth:diva-103700 (URN)10.1109/ICTON.2012.6253839 (DOI)000335346900136 ()2-s2.0-84867002609 (Scopus ID)
Conference
14th International Conference on Transparent Optical Networks (ICTON), 2012
Projects
Energy-efficient wireless networking (eWIN)Wireless@KTH
Funder
ICT - The Next GenerationWireless@kth
Note

QC 20121108

Available from: 2012-10-18 Created: 2012-10-18 Last updated: 2014-10-14Bibliographically approved
4. Is backhaul becoming a bottleneck for green wireless access networks?
Open this publication in new window or tab >>Is backhaul becoming a bottleneck for green wireless access networks?
Show others...
2014 (English)In: 2014 IEEE International Conference on Communications, ICC 2014, IEEE , 2014, 4029-4035 p.Conference paper, Published paper (Refereed)
Abstract [en]

Mobile operators are facing an exponential traffic growth due to the proliferation of portable devices that require a high-capacity connectivity. This, in turn, leads to a tremendous increase of the energy consumption of wireless access networks. A promising solution to this problem is the concept of heterogeneous networks, which is based on the dense deployment of low-cost and low-power base stations, in addition to the traditional macro cells. However, in such a scenario the energy consumed by the backhaul, which aggregates the traffic from each base station towards the metro/core segment, becomes significant and may limit the advantages of heterogeneous network deployments. This paper aims at assessing the impact of backhaul on the energy consumption of wireless access networks, taking into consideration different data traffic requirements (i.e., from todays to 2020 traffic levels). Three backhaul architectures combining different technologies (i.e., copper, fiber, and microwave) are considered. Results show that backhaul can amount to up to 50% of the power consumption of a wireless access network. On the other hand, hybrid backhaul architectures that combines fiber and microwave performs relatively well in scenarios where the wireless network is characterized by a high small-base-stations penetration rate.

Place, publisher, year, edition, pages
IEEE, 2014
Keyword
Backhaul, Energy Efficiency, Fiber, Heterogeneous Networks, Microwave, Power Consumption, Smallcells, Traffic Model, VDSL2
National Category
Communication Systems Telecommunications
Research subject
Information and Communication Technology
Identifiers
urn:nbn:se:kth:diva-144905 (URN)10.1109/ICC.2014.6883951 (DOI)2-s2.0-84907003394 (Scopus ID)9781479920037 (ISBN)
Conference
2014 1st IEEE International Conference on Communications, ICC 2014; Sydney, NSW; Australia; 10 June 2014 through 14 June 2014
Note

QC 20150602

Available from: 2014-05-02 Created: 2014-05-02 Last updated: 2017-08-15Bibliographically approved
5. Green Backhauling for Rural Areas
Open this publication in new window or tab >>Green Backhauling for Rural Areas
Show others...
2014 (English)In: Green Backhauling for Rural Areas, IEEE , 2014Conference paper, Published paper (Refereed)
Abstract [en]

Providing wireless broadband access to rural and remote areas is becoming a big challenge for wireless operators, mostly because of the need for a cost-effective and low energy consuming mobile backhaul. However, to the best of our knowledge,energy consumption of different options for backhauling of future rural wireless broadband networks has not been studiedyet. Therefore, in this paper we assess the energy consumption of future rural wireless broadband network deployments andbackhaul technologies. In the wireless segment, two deployment strategies are considered, one with macro base station only,and one with small base stations. In the backhaul segment ,two wireless, i.e., microwave and satellite, and one optical fiber based (i.e., long reach passive optical networks) solutions areconsidered. These options are compared in terms of their abilityto satisfy coverage, capacity and QoS requirements of a numberof rural users in the time span that goes from 2010 until 2021. From the presented results it is possible to conclude that wireless backhaul solutions can significantly increase the energy consumption of the access network. In contrast, the long reach PON based backhaul has much higher energy efficiency and inthe long term might be a better choice for wireless operators.

Place, publisher, year, edition, pages
IEEE, 2014
Keyword
Energy Efficiency, Backhaul, Fiber, Microwave, Satellite, Power Consumption, Traffic Model.
National Category
Telecommunications Communication Systems
Research subject
Information and Communication Technology
Identifiers
urn:nbn:se:kth:diva-144906 (URN)2-s2.0-84905443713 (Scopus ID)
Conference
18th International Conference on Optical Network Design and Modeling
Note

QP 2014

Available from: 2014-05-02 Created: 2014-05-02 Last updated: 2017-08-15Bibliographically approved
6. Impact of Densification on Energy Efficiency in Wireless Access Networks
Open this publication in new window or tab >>Impact of Densification on Energy Efficiency in Wireless Access Networks
2012 (English)In: Globecom Workshops (GC Wkshps), 2012 IEEE, IEEE , 2012, 57-62 p.Conference paper, Published paper (Refereed)
Abstract [en]

Mobile communication networks alone consume 0.5 percent of the global energy today. Rapidly growing demand for capacity will further increase the energy consumption. Thus, improving energy efficiency has recently gained great interest within the research community not only for environmental awareness but also to lower the operational cost of network operators. Base station deployment strategy is one of the key challenges to be addressed for fulfilling the future capacity demand in an energy efficient manner. In this paper, we investigate the relationship between energy efficiency and densification with regard to network capacity requirement. To this end, we refine the base station power consumption model such that the parameters are determined by the maximum transmit power and develop a simple analytical framework to derive the optimum transmit power that maximizes energy efficiency for a certain capacity target. Our framework takes into account interference, noise and backhaul power consumption. Numerical results show that deployment of smaller cells significantly reduces the base station transmit power, and thus shifts the key elements of energy consumption to idling and backhauling power. Network densification can only be justified when capacity expansion is anticipated.

Place, publisher, year, edition, pages
IEEE, 2012
Series
IEEE Globecom Workshops, ISSN 2166-0069
Keyword
Energy Efficiency, Backhaul, Densification, Network Capacity, Power Consumption
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-104658 (URN)10.1109/GLOCOMW.2012.6477544 (DOI)000320611800011 ()2-s2.0-84875679320 (Scopus ID)978-1-4673-4941-3 (ISBN)
Conference
2012 IEEE Globecom Workshops, GC Wkshps 2012; Anaheim, CA; United States; 3 December 2012 through 7 December 2012
Projects
Energy-efficient wireless networking (eWIN)
Funder
ICT - The Next GenerationWireless@kth
Note

QC 20121109

Available from: 2012-11-08 Created: 2012-11-08 Last updated: 2014-05-05Bibliographically approved
7. Energy Efficiency Improvements Through Heterogeneous Networks in Diverse Traffic Distribution Scenarios
Open this publication in new window or tab >>Energy Efficiency Improvements Through Heterogeneous Networks in Diverse Traffic Distribution Scenarios
2011 (English)In: 2011 6th International ICST Conference on Communications and Networking in China (Chinacom11), 2011, 708-713 p.Conference paper, Published paper (Refereed)
Abstract [en]

Energy Efficiency in cellular mobile radio networks has recently gained great interest in the research community. Besides the positive effect on global climate change, lowering power consumption of mobile networks is beneficial in terms of decreasing the operational cost for network operators. In this regard, the development of more energy efficient hardware and software components aside, effect of different deployment strategies on energy efficiency are also studied in the literature. In this paper, we investigate the energy efficiency improvements through different heterogeneous networks for both uniform and non-uniform traffic distribution scenarios. It has been shown that, using small power low base stations at the cell border decreases the power consumption significantly for both traffic scenarios and the most energy efficient deployment strategy highly depends on the area throughput demand of the system.

Keyword
Power Consumption, Heterogeneous Networks, Energy Efficiency, Hotspots, Network Deployment
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-75003 (URN)10.1109/ChinaCom.2011.6158246 (DOI)000305758800138 ()2-s2.0-84858257733 (Scopus ID)
Conference
6th International ICST Conference on Communications and Networking in China(Chinacom11), Harbin, China, 17-19 Aug. 2011
Projects
Energy-efficient wireless networking (eWIN)
Funder
Wireless@kth
Note

QC 20120416

Available from: 2012-02-04 Created: 2012-02-04 Last updated: 2014-05-05Bibliographically approved
8. Energy Efficiency Assessment of Wireless AccessNetworks Utilizing Indoor Base Stations
Open this publication in new window or tab >>Energy Efficiency Assessment of Wireless AccessNetworks Utilizing Indoor Base Stations
2013 (English)In: 2013 IEEE 24th International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), IEEE conference proceedings, 2013, 3105-3110 p.Conference paper, Published paper (Refereed)
Abstract [en]

Energy efficiency in mobile radio networks has recently gained great interest due to escalating energy cost and environmental concerns. Rapidly growing demand for capacity will require denser and denser networks which further increase the energy consumption. In this regard, the deployment of small cells under macro-cellular umbrella coverage appears a promising solution to cope with the explosive demand in an energy efficient manner. In this paper, we investigate the impact of joint macro-and femtocell deployment on energy efficiency of wireless access networks, based on varying area throughput requirements. We take into account the the co-channel interference, fraction of indoor users, femto base station density and backhaul power consumption. It is shown that utilizing indoor base stations provide significant energy savings compared to traditional macro only network in urban areas with medium and high user demand where the gain increases up to 75 percent as more data traffic is offloaded to femtocells.

Place, publisher, year, edition, pages
IEEE conference proceedings, 2013
Series
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, ISSN 2166-9570
Keyword
Energy Efficiency, Femtocells, Co-channel Deployment, Backhaul, Power Consumption
National Category
Communication Systems
Research subject
SRA - Energy
Identifiers
urn:nbn:se:kth:diva-133930 (URN)10.1109/PIMRC.2013.6666680 (DOI)000346481203035 ()2-s2.0-84893305207 (Scopus ID)978-146736235-1 (ISBN)
Conference
2013 IEEE 24th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications, PIMRC 2013; London; United Kingdom; 8 September 2013 through 11 September 2013
Projects
Energy-efficient wireless networking (eWIN)
Funder
Wireless@kth
Note

QC 20131218

Available from: 2013-11-13 Created: 2013-11-13 Last updated: 2015-12-03Bibliographically approved
9. Energy Efficient Network Deployment with Cell DTX
Open this publication in new window or tab >>Energy Efficient Network Deployment with Cell DTX
2014 (English)In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 18, no 6, 977-980 p.Article in journal (Refereed) Published
Abstract [en]

Cell discontinuous transmission (DTX) is a newfeature that enables sleep mode operations at base station (BS)side during the transmission time intervals (TTIs) when thereis no traffic. In this letter, we analyze the maximum achievableenergy saving of the cell DTX. We incorporate the cell DTXwith a clean-slate network deployment, and obtain optimal BSdensity for lowest energy consumption satisfying a certain qualityof service (QoS) requirement considering daily traffic variation.The numerical result indicates that the fast traffic adaptationcapability of cell DTX favors dense network deployment withlightly loaded cells, which brings about considerable improvementin energy saving.

Place, publisher, year, edition, pages
IEEE Communications Society, 2014
Keyword
Energy Efficiency, Cell DTX, Network Deployment, Cell Load, Traffic Profile.
National Category
Communication Systems Telecommunications
Research subject
Information and Communication Technology
Identifiers
urn:nbn:se:kth:diva-144904 (URN)10.1109/LCOMM.2014.2323960 (DOI)000340115200020 ()2-s2.0-84902139351 (Scopus ID)
Projects
5Green, EIT ICT Labs
Funder
Wireless@kth
Note

QC 20150623

Available from: 2014-05-02 Created: 2014-05-02 Last updated: 2017-12-05Bibliographically approved
10. Energy- and cost-efficient ultra-high-capacity wireless access
Open this publication in new window or tab >>Energy- and cost-efficient ultra-high-capacity wireless access
2011 (English)In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 18, no 5, 18-24 p.Article in journal (Refereed) Published
Abstract [en]

Mobile communication networks alone today consume 0.5 percent of the global energy supply. Meeting the rapidly increasing demand for more capacity in wireless broadband access will further increase the energy consumption. Operators are now facing both investing in denser and denser networks as well as increased energy cost. Traditional design paradigms, based on assumptions of spectrum shortage and high cost base station sites, have produced current cellular systems based on 3G and 4G (LTE) standards. The latter ones are characterized by very high spectrum efficiency, but low energy efficiency. Deployment has favored strategies with few high-power bases stations with complex antenna systems. The key method for indoor coverage has so far been to literally "blast signals through walls" - a solution that is neither energy-efficient nor very sound from a radiation perspective. As environmental aspects may be perceived as important from a societal perspective, the cost remains the short-to medium-term concern for operators of future mobile broadband systems. What becomes evident now is that the so far mostly neglected energy cost will be a major concern. Future system deployment has to balance infrastructure deployment, spectrum, and energy cost components. Ongoing incremental improvements in electronics and signal processing are bringing down the power consumption in the base station. However, these improvements are not enough to match the orders-of-magnitude increase in energy consumption cause by demands for more capacity. It is clear that solutions to this problem have to be found at the architectural level, not just by increasing the efficiency of individual components. In this article we propose a framework for a total cost analysis and survey some recent, more radical, "clean slate" approaches exploiting combinations of new spectrum opportunities, energy-efficient PHY layers, and novel deployment and backhauling strategies that target minimizing overall system cost. The latter involve network deployment tightly tailored to traffic requirements, using low-power micro base stations tailored specifically to decrease the power consumption compared to today's high-power macro base station schemes. To illustrate our findings, a power consumption model for mobile broadband access networks taking backhaul into account is presented, and the main trade-offs between infrastructure, energy, and spectrum costs are analyzed. We demonstrate optimal deployment strategies in some simple scenarios where a certain capacity has to be provided in a dense interference-limited scenario.

National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-48521 (URN)10.1109/MWC.2011.6056688 (DOI)000296242000005 ()2-s2.0-80155201296 (Scopus ID)
Projects
Energy-efficient wireless networking (eWIN)
Funder
Wireless@kth
Note

QC 20111201

Available from: 2011-12-01 Created: 2011-11-21 Last updated: 2017-12-08Bibliographically approved
11. An Economic Viability Analysis on Green Solutions for Wireless Access Networks
Open this publication in new window or tab >>An Economic Viability Analysis on Green Solutions for Wireless Access Networks
(English)Manuscript (preprint) (Other academic)
Identifiers
urn:nbn:se:kth:diva-144995 (URN)
Note

QS 2014

Available from: 2014-05-05 Created: 2014-05-05 Last updated: 2014-05-08Bibliographically approved

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