By Definition a femtocell agnostically refers to a small wireless base station or
access point. " ... Source: Kountouris, Green Radio Day, ISIS Seminar, June 12.
Energy-Efficient Hybrid cellular networks Réseaux hybrides à haute efficacité énergétique
Loutfi Nuaymi, Luis A. Suarez, REOP team Loutfi Nuaymi Cesson-Sévigné 29 juin 2012
Plan 1- Context and definitions ! 1a- Normalization and commercialization ! 2- Objectives ! 3- Model and problem description ! 4- State of the art ! 5- Our Work !
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1- Context Energy Constraints: energy contribution of ICT is XX % of the global energy consumption (Gartner, 2007) ! Mobile Data traffic increase : x2 every year or two years according to different sources ! x1000 in around 15 years (but who will verify in 15 years?) !
Example of reference: Cisco traffic forecast update, “Cisco visual networking index: global mobile data,” 2011. ! Source Fig.: Rit12, Projet Greentouch
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1- Context More research has to be done to ameliorate spectrum efficiency but much has been already done : modulation, coding, radio procedures (ex: HARQ in Layer 2). ! Recommended Survey : !
L. A. Suarez Rivera, L. Nuaymi, J.-M. Bonnin, "An overview and classification of research approaches in green wireless networks,” EURASIP journal on wireless communications and networking, april 2012 !
New approaches needed. Most of this approaches can be summarized in a few words: put the transmitter closer to the receiver !
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1- Context: generations of cellular systems Start of commercialization for different generations of cellular networks (approx): ! 1G: 1979 (Japan) ! 2G: 1991 ! 3G: 2001 ! 4G*: 2010 *3.9G for purists … Marketing : 4G ! 5G: no name available*, no initiative * 3G: IMT-2000 or UMTS was known as FPLMTS !
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1a- Normalization and commercialization of small cells! !
By Definition a femtocell agnostically refers to a small wireless base station or access point. "
!
This small element of wireless infrastructure is generally intended to quickly and inexpensively extend the wireless coverage and capacity in an indoor environment.#
" Source Fig: Femto Forum" (www.femtoforum.org)"
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""
1a- Normalization and commercialization of small cells! !
Standard Handover between micro or macro cells and Femtocells" " "Source Fig:Kineto Wireless and Femto Forum (www.femtoforum.org)"
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1a- Normalization and commercialization of small cells Commercialization of small cells: - SFR Offer in 2009: small success. - Orange Femtocell offer expected in the first part of 2013. !
!
«China Mobile is already deploying 3G femtocells, initially using the 3G standard TD-SCDMA, and later TD-LTE too» (Rethink Wireless Site, may 12)
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2- Small cells Macro cell: classical, well-known ! "small cell": many definitions … - Micro - Pico (10-12): outdoor, operator-installed for hotspot, Power order of magnitude: 100 W - Femto (10-15): indoor, user installed (DSL evolution?), Power order of magnitude: 40 W - Attocell (10-18): connection between a laptop and a smarphone, includes software for original operator association (needs operator agreement) !
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2- Small cells: Objectives !
Objectives of different types: - increase access network capacity; - operator economies (possibly!); - extension of coverage; (recently) - energy economies
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2- Small cells Top-two (by far) references: - General: V. Chandrasekhar, et al, "Femtocell Networks: A Survey," in IEEE Communications Magazine, September 2008. - OFDMA: D. Lopez-Perez, et al "OFDMA femtocells: A roadmap on interference avoidance," Communications Magazine, IEEE , vol.47, no.9, pp. 41-48, June 2009 !
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2- Small cells: how to get closer to the user? !
Illustration of the new cell layout (Figure Source: ALU, Pracom Seminar, June 12)
!
Possibility: dynamic change of the cell size, See PhD of Luis A. Suarez
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2- Small cells !
New cell sizes ! new interference issue
!
Fig. Source: Kountouris, Green Radio Day, ISIS Seminar, June 12
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3- Model and issues Interference between macro and small cells; - Position of small cell: random or deterministic? Optimized? - Why will a subscriber accept to turn his modem ("box") into a femtocell? !
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Problem Formulation: TBC
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4- State of the art !
Claussen et Al [2008]: hybrid macro/pico-BS cellular network environment. ! Estimation of energy consumption reduction and coverage enhancement ! Effect of sleep mode.
!
Micaleff et Al [2011]: study of growth strategies for an access network. ! Comparison of macro-only and hybrid macro-pico environments in a four-year evolution (interesting economic model).
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4- State of the art !
F. Cao, Z. Fan [2010]: Hybrid macro/pico-BS cellular network environment. ! Estimation of energy consumption reduction.
!
W. Wang, G. Shen [2010]: Hybrid macro/pico-BS cellular network environment. ! Estimation of energy consumption reduction for different densities of picocells installed. More picocells = increase of capacity but also more energy consumed. ! Existence of optimal picocell density. ! Effect of macrocell intersite distance on the observed indcators.
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4- State of the art !
Adapted Resource Allocation algorithms: References [5][6][7] intend to mitigate the interference produced in downlink or uplink, wether by MacroBS and associate MUEs on a femtoBS and the associated HUES and viceversa by proper radio resource allocation algorithms: bandwidth partitionning or sharing, …
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4- State of the art !
Femtocells provide energy economies in some cases and if they are: - properly dimensioned and positionned, - shut down whenever possible (! our work: trying to say when!).
!
Figure source: Rittenhouse, ALU, April 2012
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5- Our Work !
Extend Cell Breathing analysis (/* see 2 recent papers) done for macro cell to Hybrid Networks (PhD work of Luis)
!
When to wake-up small cells (same question for macro)? Possible model elements: - Include proposal of reverse-paging message, Alberto Conte, ALU, and colleagues from FP7 TREND Project* - Use LTE X2 interface between base stations to have one BS (normally macro) wake up another BS (normally small) - Use the mobiles GPS A. Conte et al, "Cell wilting and blossoming for energy efficiency", IEEE Wir. Com. Oct 11
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Specific LTE-A environment
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References !
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[1] H Claussen, LTW Ho, F Privit, Effects of joint macrocell and residential picocell deployment on the network energy efficiency, in Proc. of PIMRC 2008, vol., no., pp.1-6 , Cannes, France, September 2008 [2] G Micaleff, P Mogensen, HO Scheck, E Lang, Energy efficient evolution of mobile networks macro-only upgrades vs. a joint-pico deployment strategy, in Conf.VTC (Spring) 2011, vol., no., pp. 1-5, Budapest, Hungary, May 2011 [3] Fengming Cao; Zhong Fan, "The tradeoff between energy efficiency and system performance of femtocell deployment," Wireless Communication Systems (ISWCS), 2010 7th International Symposium on , vol., no., pp.315-319, 19-22 Sept. 2010 [4] Wei Wang; Gang Shen; , "Energy Efficiency of Heterogeneous Cellular Network," Vehicular Technology Conference Fall (VTC 2010-Fall), 2010 IEEE 72nd , vol., no., pp. 1-5, 6-9 Sept. 2010 [5] I Güvenc, Moo-Ryong Jeong, F Watanabe, H Inamura, A hybrid frequency assignment for femtocells and coverage area analysis for co-channel operation. IEEE Commun. Lett. 12(12), vol. 12, no. 12, pp. 880-882, (2008) [6] Yong Bai, Juejia Zhou, Lan Chen, Hybrid spectrum usage for overlaying LTE macrocell and femtocell, in Proc. IEEE Globecom 2009, vol., no., pp. 1-6, Hawaii, USA, November 2009 [7] Lin Yang; Lu Zhang; Tao Yang; Wei Fang ; " Location-Based Hybrid Spectrum Allocation and Reuse for Tiered LTE-A Networks," Vehicular Technology Conference (VTC Spring), 2011 IEEE 73rd , vol., no., pp.1-5, 15-18 May 2011
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