Is there a spectrum shortage? The answer to the question is both yes and no; in some locations spectrum is severely congested, while in other places it is highly underutilized

1. A BOOSTER FOR BACKHAUL ✱
JANUARY 25, 2016 ✱ ERICSSON TECHNOLOGY REVIEW 1
C H A R T I N G T H E F U T U R E O F I N N O V A T I O N V O L U M E 9 3 | # 1 ∙ 2 0 1 6
MICROWAVEBACKHAUL
GETSABOOSTWITH
MULTIBAND
ERICSSON
TECHNOLOGY
Distance (km)
0
0
5
10
15
20
25
10 20 30 40 50 60 70 80 90
Frequency (GHz)
Bands
Limit without fading
99.9% availability, mild climate
99.9% availability, severe climate
99.999% availability, mild climate
99.999% availability, severe climate
Multiband potential

2. ✱ A BOOSTER FOR BACKHAUL
2 ERICSSON TECHNOLOGY REVIEW ✱ JANUARY 25, 2016
JONAS EDSTAM Is there a spectrum shortage? The answer to the question is both yes and no;
in some locations spectrum is severely congested, while in other places it is
highly underutilized. As the performance level demands on services like mobile
broadband continue to rise, networks are going to need some innovative tools.
New methods that will maximize spectrum efficiency, and new technologies
that can exploit unused spectrum are going to be needed. Multiband booster
is one such method. This concept fundamentally shifts the way spectrum can
be used, with a promise to deliver a massive improvement in the performance
levels of microwave backhaul, while at the same time accelerating the much
needed shift toward the use of higher frequency bands..
Microwave
backhaulGETS A BOOST WITH MULTIBAND

3. A BOOSTER FOR BACKHAUL ✱
JANUARY 25, 2016 ✱ ERICSSON TECHNOLOGY REVIEW 3
Te c h n o l o g y e v o l u t i o n, increased
mobility, and massive digitalization
continue to place ever more demanding
performance requirements on networks –
a trend that shows no signs of leveling off.
As the dominant backhaul media in today’s
networks, microwave plays a significant
role in providing good mobile network
performance. However, the constant
pressure to increase performance levels
translates into a need for more spectrum,
and more efficient use of it – not just when
it comes to radio access, but for microwave
backhaul as well.
Asafinitenaturalresource,radiospectrumis
governedbynationalandinternationalregulations
toensurethatsocialandeconomicbenefitsare
maximized.Spectrumisdividedintofrequency
bandsthatareallocatedtodifferenttypesofradio
services,suchascommunication,broadcasting,
radar,aswellasscientificuse.Allocationisbased
onpropagationcharacteristics,whichvarywith
frequency.Lowerfrequencies,forexample,
enableradiosignalstobetransmittedoverlonger
distances,andcanpenetratebuildingfacades.
Higherfrequencies,ontheotherhand,aremore
limitedintermsofreachandcoverage,buttheycan
generallyprovidewiderfrequencybands,andas
suchhavehighdata-carryingcapacities.Driven
bygrowingcommunicationneeds,everhigher
frequencieshavebeentakenintouseoverthepast
fewdecades.Historically,microwavebackhaulhas
usedmuchhigherfrequencies(fromabout6GHzto
86GHz)thanmobileradioaccess,whichtodayuses
spectrumrangingfromabout400MHzto4GHz.
For5Gradioaccess,researchiscurrentlyunderway
ontheuseofmuchhigherfrequencies(above
24GHz).Thefindingsofthisworkwillbepresented
atthenextitu WorldRadiocommunication
Conference,duetobeheldin2019(wrc-19)[1].
By2020,65percentofallcellsites(excluding
thoseinNortheastAsia)willbeconnectedtothe
restofthenetworkusingmicrowavebackhaul
technology[2].Betweennowandthen,the
performanceofmicrowavebackhaulwillcontinue
toimprove,supportinggrowingcapacityneeds
throughtechnologyevolutionandmoreefficient
useofspectrum.Thedecision-makingprocessused
toestablishwhatmediacanbestprovidebackhaul
toagivensitewillalsochange;itwillnolongerbe
determinedbycapacityneeds,butratherwhich
solution–fiberormicrowavebackhaul–provides
thelowesttotalcostofownership(tco).
Multibandsolutions,whichenableenhanceddata
ratesbycombiningresourcesinmultiplefrequency
bands,alreadyconstituteanessentialpartof
modernradioaccesssystems.Theirsignificance
will,however,increaseinthecomingyears,asthey
enableefficientuseofdiversespectrumassets,
andassuchwillsupporttheevolutionoflte and
5g technologies.
Thequestiontoday,however,ishowtoexploit
themultibandconceptforbackhaul.Andhowcan
aholisticviewenablemoreefficientuseofdiverse
backhaulspectrumassets.
Useofspectrumforbackhaul
Spectrumindifferentfrequencyrangesisusedby
backhaulsolutionstosupportcommunicationin
manytypesoflocations,fromsparselypopulated
ruralareastoultra-denseurbanenvironments.
Termsandabbreviations
pdh–Plesiochronous Digital Hierarchy | qam–quadrature amplitude modulation |
sdh–Synchronous Digital Hierarchy

4. ✱ A BOOSTER FOR BACKHAUL
4 ERICSSON TECHNOLOGY REVIEW ✱ JANUARY 25, 2016
Northern Europe
and Central Asia
Middle East
India
Southeast Asia
and Oceania
Northeast Asia
Western and
Central Europe
Mediterranean
Sub-Saharan
Africa
Latin America
North America
Region 6 7 8 10 11 13 15 18 23 26 28 32 38 42 60 70/80
Frequency band (GHz)
Source: Ericsson 2015
Figure 1:
Global use of microwave
backhaul
Globally,about4millionmicrowavebackhaul
hopsareinoperationtoday.Figure 1illustrates
theextentofmicrowavebackhaulusagebyregion
andband–thesizeofeachcircleisrelativetothe
numberofmicrowavehopsinoperation.Which
frequencybandisusedvariesgreatlyfromoneplace
tothenext,becausethemostappropriatebandis
chosendependingonregionalclimateandnational
spectrumregulations[3].Otherfactorslikeinter-
sitedistance,targetperformancerequirements,and
fiberpenetrationarealsotakenintoconsideration
whenselectingthebackhaulfrequencybandthat
bestfitsagivenlocation.
Ascapacityneedshavegrown,theuseof
spectrumhasshifted.Higher,previouslylessutilized
frequencieshavegrowninpopularity.Abouta
decadeago,new26GHz,28GHz,and32GHzbands
wereintroduced,andsincethen,theuseofthese
bandstosupportlte backhaulhasbecomepopular
inpartsofEurope,CentralAsia,theMediterranean,
andtheMiddleEast.Theolder38GHzbandisquite
popularintheseregions,anditsattractivenessis
currentlygrowingintherestoftheworld.Thenewer
70/80GHzbandistodaygainingpopularity[2,4],as
itofferswidespectrumandchannelsalike,enabling
capacitiesinthe10Gbpsrangeoverafewkilometers.
Lookingtothefuture,industryhasaninterestin
theuseoffrequenciesabove100GHz,astheywill
enablecapacitiesinthe40Gbpsrangeoverhop
distancesofaboutakilometer[2].
Technologiesarebeinginvestigated[5],
andregulatorystudiesareexaminingchannel
arrangementsanddeploymentscenariosinthe
92-114.5GHz,and130-174.7GHzfrequencyranges,
commonlyreferredtoastheW-andD-bandfor
microwavebackhaul[6].
Unfortunately,theuseofspectrumisunbalanced:
hotspotsoccurinbandsthatareheavilyused,while
therearelargegeographicalareaswithuntapped
spectruminallfrequencybands.

5. A BOOSTER FOR BACKHAUL ✱
JANUARY 25, 2016 ✱ ERICSSON TECHNOLOGY REVIEW 5
Microwavebackhaultechnology
Unlikethevariousgenerationsofradioaccess
technology(2G,3G,and4G),thereisnoformal
classificationformicrowavebackhaultechnology
evolution.Nevertheless,itsperformancehas
improvedtremendouslyoverthepastfewdecades
withtheintroductionofinnovativetechnologiesand
enhancedfeatures[2,7,8].
Oneissuethatinsomewaycharacterizes
microwavebackhaulistheimpactonsignal
strengthofadversepropagationeffects,suchas
thosecausedbyrain.Planninganddimensioning
ofmicrowavelinksneedtobecarriedoutusing
recommendedpropagationpredictionmethodsand
long-termstatistics,toensurethattargetedservice
availability(theratioofactualserviceprovidedtothe
targetedservicelevel,measuredover365days,and
expressedasapercentage)canbesecured[9].
Originally,microwavesupportedpdh andsdh
transportusingfixedmodulationdesignedfora
serviceavailabilityofupto99.999percent(five-nines
availability),whichallowsforfiveminutesoftotal
outageinayear.
Sincethen,adaptivemodulationhasbeen
introducedforpackettransport:atechniquethat
isnowwellestablished,andsupportsextreme
ordermodulationwithupto4096qam.Adaptive
modulationmaximizesthebit-error-freethroughput
underallpropagationconditions.Itcanbe
configuredtoprovideguaranteedcapacityfor
high-availabilityservices,andstillprovidemore
thandoublethecapacitywithsomewhatlower
availability,asillustratedinFigure 2.
Multibandboosterforbackhaul
Radio-linkbondingisawell-establishedmethod
formicrowavebackhaul,enablingmultipleradio
carrierstobeaggregatedintoasinglevirtualone[7]
–somewhatsimilartocarrieraggregationinradio
access.Bondingnotonlyenhancespeakcapacity,
Figure 2:
Evolution of microwave
backhaul technology
Capacity
363 days 365 days Availability
99.5%
99.9%
99.95%
99.99%
99.995%
99.999%
1.8 days
8.8 hours
4.4 hours
53 minutes
26 minutes
5 minutes
Unavailability
30 minutes
Multiband
Adaptive modulation (4096 QAM)
Fixed modulation (128 QAM)
High band
Low band

6. ✱ A BOOSTER FOR BACKHAUL
6 ERICSSON TECHNOLOGY REVIEW ✱ JANUARY 25, 2016
Distance (km)
0
0
5
10
15
20
25
10 20 30 40 50 60 70 80 90
Frequency (GHz)
Bands
Limit without fading
99.9% availability, mild climate
99.9% availability, severe climate
99.999% availability, mild climate
99.999% availability, severe climate
Multiband potential
Figure 3:
Achievable distances with high-capacity microwave backhaul
363 days
4Gbps
600Mbps
1.5Gbps
300Mbps
1.5Gbps
300Mbps
365 days
363 days 365 days
363 days 365 days
Moderate climate
5km distance
70/80GHz, 500MHz channel, 256 QAM
23GHz, 56MHz channel, 4096 QAM
Moderate climate
12km distance
38GHz, 112MHz channel, 4096 QAM
15GHz, 28MHz channel, 4096 QAM
Moderate climate
25km distance
23GHz, 112MHz channel, 4096 QAM
7GHz, 28MHz channel, 4096 QAM
Figure 4:
Examples of multiband microwave backhaul configurations

7. A BOOSTER FOR BACKHAUL ✱
JANUARY 25, 2016 ✱ ERICSSON TECHNOLOGY REVIEW 7
italsoincreaseseffectivethroughputbyusing
statisticalmultiplexing.Sinceitsintroduction,the
technologyhasevolvedcontinuously,supporting
ever-highercapacitiesandmoreflexiblecarrier
combinations.Sofar,focushasbeenonbonding
carrierswithinthesamefrequencyband.Thebeauty
ofthemultibandboosterconceptliesinthefact
thatitusesradio-linkbondingtoaggregatecarriers
indifferentfrequencybands,enablingthefull
spectrumpotentialtobeunleashed.
Widerchannelsareeasiertoobtainathigher
frequencies,butasrainattenuationincreaseswith
frequency,availabilitydropsforagivendistance.
Multibandboosterovercomesthisissuebybonding
awidehigh-frequencychannelwithanarrowlow-
frequencychannel,asillustratedinFigure 2.The
resultingcombinationprovidesthebestofboth
channels,givinghighercapacitiesovermuchlonger
distances–drasticallychangingthewayspectrum
canbeusedforbackhaul.Multibandbooster
bringsaboutahugeincreaseinperformance,and
introducesahighdegreeofflexibilityintothedesign
ofthebackhaulsolution.Ultimately,itenablesthe
performanceandavailabilityrequirementsfor
differentservicestobemet.
Howdifferentmicrowavebackhaulfrequency
rangescanbeusedistoalargeextentdetermined
bypropagationproperties[9].Asrainattenuation
andfree-spacelossesincreasewithfrequency,the
achievablehopdistanceathigherfrequenciesis
limited.Themaximumdistancesforhigh-capacity
microwaveareshowninFigure 3fordifferent
climatesandlevelsofavailability.Themildclimate
hasarainzoneofabout30mmperhour(rainrate
exceededfor0.01percentoftheyear),andistypical
forlargepartsofEurope.Thesevereclimateisfora
rainzoneofabout90mmperhour,whichistypical
forIndia.Theavailabilitytargetsinthisexample
aresetforhalfthemaximumlinkcapacity,which
correspondsto64outof4096qam inthe6-42GHz
range,andto16outof256qam inthe60GHzand
70/80GHzbands.Thefulllinkcapacityhaslower
availability,butismaintainedformostoftheyear.
Forapplicationsthatrequirelowercapacities,longer
distancescanbeachievedusinglowermodulation
levels.Figure 3alsoshowsthelimitformaximum
modulationwithoutfading,stillincludingfree-
spacelossandatmosphericattenuation.Theoxygen
absorptionpeak,whichoccursataround60GHz,
severelylimitshopdistance–thisphenomenonis
clearlyillustratedbythedipinthecurve.
Thewidthofafrequencybandgenerallyscales
withfrequency;thehigherthefrequency,themore
bandwidthitoffers.Backhaulfrequencybandscan
beroughlycategorizedintothreefrequencyranges:
〉〉 6-15GHzbandswithanaverageof750MHzperband
〉〉 18-42GHzbandswithanaverageof2.2GHzperband
〉〉 70/80GHzbandthatis10GHzwide.
Foragivenhopdistance,thetypicalmultiband
combinationsthatwouldboostcapacityare
illustratedinFigure 3.Theyinclude:18-42GHz
bandsbondedwiththeverywide70/80GHzband
forhopdistancesofuptoabout5km;orthenarrow
6-15GHzbandsbondedwiththewider18-42GHz
bandsforlongerhopdistances.Themultiband
solutionis,however,highlyflexible,andanylocally
availablefrequencycombinationsthatmeetthe
targetedperformancecanbeused.
Boostingbackhaulperformance
Themultibandboosterisanexcellenttoolfor
upgradingthecapacityofmicrowavebackhaul
networksuptotenfold.Figure 4showsthree
differentmultibandexampleswithtypicalhop
distancesfoundindifferentpartsofthenetwork–
insuburbanareashopstendtobeafewkilometers
long,andtensofkilometersinremoteruralregions.
Examplesaregivenforamoderateclimate,witha
rainzoneofabout60mmperhour(whichistypical
forplaceslikeMexico).Bearinginmindthatthese
configurationsarejustexamples,themultiband
boosterprovidesahighlyflexiblewaytobond
differentcarrierandfrequencybandcombinations.
Combiningdifferentfrequencybandsmakesit
possibletogetmoreoutofavailablespectrum,
andsohelpnetworksmeettheperformanceand
availabilityrequirementsoffutureservices.
Unleashingspectrumpotential
Itisclearthatifnetworksaretomeetfuture
performancerequirements,efficientuseofspectrum

8. ✱ A BOOSTER FOR BACKHAUL
8 ERICSSON TECHNOLOGY REVIEW ✱ JANUARY 25, 2016
High availability
Lower availability
Multiband
70/80GHz
18–42GHz
6–15GHz
Dense urban Remote rural
Figure 5:
Efficient use of microwave backhaul spectrum
Global deployments per frequency range
0
0%
100%
10 20 30 40 50 60 70 80 90
Frequency (GHz)
Bands
Multiband potential
Single band today
Figure 6:
Increased use of high frequencies with multiband microwave backhaul

9. A BOOSTER FOR BACKHAUL ✱
JANUARY 25, 2016 ✱ ERICSSON TECHNOLOGY REVIEW 9
isessential.Thereare,however,manydifferent
aspectstospectrumefficiency,andthelevelthat
canbeachieveddirectlydependsonthelocal
deploymentdensityandtopologyofmicrowavehops.
Microwavebackhaulperformanceis,forthemost
part,determinedbythepropagationpropertiesof
differentfrequencies.Athigherfrequencies,rain
attenuationandfree-spacelossesaregreater,while
antennasizedropsforthesameantennagain.Best
practicedictatesusingthehighestfrequencyband
possiblethatcanstillmeettheavailabilityand
performanceobjectivesforagivenlinkdistance.
Thisapproachpreservesthelowerfrequencybands
forusebygreaterlinkdistances.Inmanycountries,
regulatoryincentivespromotetheuseofhigher
bandsthroughlowerspectrum-licensingcosts,and
byimposingpoliciesthatdictateminimumhop-
lengthdistances.
Increasingthespectralefficiencyofalinkcan
beachievedbyusinghigher-ordermodulation,
butthiscomesatthecostofincreasedsensitivity
tointerference–whichmayinturnlimittheuseof
moreextremeordermodulationinlocalhotspots.
Consequently,thesignificanceofinterference
mitigationtechnologies,likesuperhighperformance
antennas(Class4[10]),isgrowing.
Today,theuseofhigherfrequencybandsis
limitedtoshorterhoplengths,whichtendtobemost
commoninurbanenvironments.Asaresult,higher-
frequencyspectrumisseldomusedoutsidethese
areas.Clearlysuchbiasedusageisinefficient,and
asignificantamountofvaluablespectrumremains
untapped.
AsFigure 5illustrates,themultibandbooster
enableshigherbackhaulfrequencybandstobe
usedoverlongerdistancesandmuchwiderareas.
Theconceptcanbeappliedtoadvantageinall
geographicalareas,althoughdifferentfrequency
bandsareappropriatedependingonthedesired
hopdistance.Widerchannelsshouldalsobemuch
easiertoobtainintheselesscongestedareas,further
increasingthebenefitofmultibandsolutions.
Regulatoryauthoritiescanapplydifferent
licensingmodelstoencourageefficientuseof
spectrum,weighinginfactorslikefrequencybands,
geographicregion,andlocalmicrowavehopdensity.
Introducingandallowingwiderchannelsinless
deployedareaswouldfurtherencouragetheuseof
multibandsolutions.
Futurebackhaulspectrumuse
Inmostgeographicalareas,hopdistancesare
generallybecomingshorterduetothedensification
ofthemacrocellnetworkandintroductionofsmall
cells.Likewise,thedistancetoafiberpoint-of-
presenceisdroppingasfiberpenetrationincreases.
Ashopdistancesfall,theuseofhigherfrequency
bandsrises.Forexample,useofthe70/80GHz
bandisgrowingsignificantly,andifthegrowth
curvecontinues,willaccountfor20percentof
newdeploymentsby2020[2].Today,bandsinthe
26-42GHzrangearepredominatelyusedinEurope,
theMediterranean,CentralAsiaandMiddleEast
(seeFigure 1),butuseinotherregionsisbeginningto
showsignsofgrowth.
Figure 6showstherelativeamountofsingle-
bandmicrowavehopsinglobaloperationtodayin
the6-15GHz,18-42GHz,and70/80GHzfrequency
ranges(seealsoFigure 1).Themultibandboosteris
ahighlyattractivesolutiontoenhanceperformance
formicrowavebackhaul.Upgradingexistingsingle-
bandmicrowavelinkstomultibandsolutionswill
resultintheaccelerateduseofhigherfrequency
bands,asillustratedinFigure 6.
Densernetworks,increasingperformanceneeds,
andnewefficienttechnologies,suchasmultiband
booster,willallleadtoadramaticincreaseintheuse
ofthe70/80GHzband,aswellasalargeincreasein
theuseofbandsinthe18-42GHzrange.
Summaryandconclusions
Theperformanceofmicrowavebackhaulhas
evolvedcontinuouslywithnewandenhanced
technologiesandfeaturesthatmakeeverbetteruse
ofavailablespectrum[2,7,8].Today,microwave
backhaulcanprovidefiber-likemulti-gigabit
capacity–eveninlocationswherethereisnodirect
line-of-sight[11].
Multibandsolutionsareessentialformobile
systems,astheyenablediversespectrumassetsto
beusedefficiently.Theimportanceofthesetypes
ofsolutionsformobilecommunicationwillriseas

10. ✱ A BOOSTER FOR BACKHAUL
10 ERICSSON TECHNOLOGY REVIEW ✱ JANUARY 25, 2016
lte evolvesand5Gbecomesareality.Anumberof
yearsago,wedocumentedthebenefitsofadapting
multibandformicrowavebackhaulinaprevious
article[7].It'snowtimetofullyexploittheconcept.
Multibandboosterprovidesamassiveincreasein
theperformanceofmicrowavebackhaul,andisan
excellenttoolthatcanincreasenetworkcapacityup
totenfold.Itsupportsflexiblebondingofdifferent
carriersandfrequencybandcombinations,enabling
networkstomeettheperformanceandavailability
requirementsforfutureservices.Multibandbooster
representsaparadigmshifttowardmuchmore
efficientuseofdiversebackhaulspectrumassets,
unleashingtheuseofhigherfrequenciesovermuch
widergeographicalareas.
Thetechnologyevolutionforspectrum–howit
isusedandhowitisallocated–ismovingfast,with
manynewinnovationsbecomingavailableforboth
radioaccessandmicrowavebackhaul.Regulatory
authoritiesarecarefullyconsideringthecurrentand
futureuseoffrequencybands,notonlyformobile
systemsbutalsoformicrowavebackhaul.
Asnetworksbecomedenser,andperformance
needsgrow,newefficienttechnologies,likethe
multibandbooster,willdramaticallyincreasetheuse
ofthe70/80GHzband,aswellasthebandsinthe
18-42GHzrange.Tosupportevolvingtechnology,
andensuregoodbackhaulperformance,regulatory
incentivesthatpromoteefficientandholisticuseof
backhaulspectrumarekey.

11. A BOOSTER FOR BACKHAUL ✱
JANUARY 25, 2016 ✱ ERICSSON TECHNOLOGY REVIEW 11
Jonas Edstam
joined Ericsson in 1995, and
is responsible for technology
strategiesandindustry-wide
collaborations at Product
Area Microwave Networks,
Business Unit Radio. He
is an expert in microwave
backhaul networks, having
more than 20 years of
experience in this area.
Throughout his career, he
has fulfilled various roles,
working on a wide range of
topics including detailed
microwave technology
and system design. His
current focus is on the
strategic evolution of mobile
networks and wireless
backhaul to 5G. He holds
a Ph.D. in physics from
Chalmers University of
Technology, Gothenburg,
Sweden.
theauthor
Jonas greatly acknowledges the support and inspiration of his colleagues:
Git Sellin, Martin Sjödin, Björn Bäckemo, David Gerdin, Anders Henriksson,
Peter Björk, Jonas Hansryd, Jonas Flodin, and Mikael Öhberg.
References
1. ITU-R, 2015, Provisional Final Acts World Radio Conference (WRC-15),
Resolution COM6/20 (pages 424-426), available at: http://ow.ly/Xg4Ci
2. Ericsson, Sep 2015, Microwave Towards 2020 Report, available at:
http://www.ericsson.com/res/docs/2015/microwave-2020-report.pdf
3. ITU-R, 2012, Recommendation F.746, Radio-frequency arrangements for
fixed service systems, available at: https://www.itu.int/rec/R-REC-F.746/en
4. ETSI, June 2015, white paper no. 9, E-Band and V-Band - Survey on status of
worldwide regulations, available at: http://ow.ly/Xg4JA
5. IEEE, 2014, A Highly Integrated Chipset for 40 Gbps Wireless D-Band
Communication Based on a 250 nm InP DHBT Technology, Abstract
available at:
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6978535
6. CEPT ECC WG SE19, Work items SE19_37 and SE19_38, available at:
http://eccwp.cept.org/default.aspx?groupid=45
7. Ericsson Review, June 2011, Microwave capacity evolution, available at:
http://ow.ly/Xg4OU
8. Ericsson, Microwave Towards 2020 Report, September 2014, available at:
http://www.ericsson.com/res/docs/2014/microwave-towards-2020.pdf
9. ITU-R, 2015, Recommendation P.530, Propagation data and prediction
methods required for the design of terrestrial line-of-sight systems, available
at: https://www.itu.int/rec/R-REC-P.530/en
10. ETSI, 2010, ETSI EN 302-217-4-2, Fixed Radio Systems - Characteristics and
requirements for point-to-point equipment and antennas available at:
http://ow.ly/Xg4Vg
11. Ericsson Review, February 2013, Non-line-of-sight microwave backhaul for
small cells, available at: http://ow.ly/Xg4YM

12. ✱ A BOOSTER FOR BACKHAUL
12 ERICSSON TECHNOLOGY REVIEW ✱ JANUARY 25, 2016
ISSN 0014-0171
284 23-3274 | Uen
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