Comments on the RDOF Uplink Service Objective...Comments on the RDOF Uplink Service Objective Ex...
Transcript of Comments on the RDOF Uplink Service Objective...Comments on the RDOF Uplink Service Objective Ex...
LYAandc-AheadareregisteredtrademarksofLemay-YatesAssociatesInc.©LYA,2019
December19,2019
Comments on the RDOF Uplink Service Objective Ex parte presentation – FCC Docket 19-126
¢ The 20 Mbps uplink objec9ve likely adds substan9al cost without correspondingconsumerbenefit.� Traffic is typically 90% download/10% upload – thus unlike 100/20, the 10/1, 25/3, 50/5
Mbpsservice9ersarebeHermatcheswithactualtrafficusage.
¢ Inconsideringfixedwirelessdeploymentscenarios,a20Mbpsuplink9er likelyaddstwo to three9mes the cost compared to a10Mbpsuplinkdeployment, due to theneedtobuildaddi9onalsites.� Theseincreasedcoststranslateto:
¢ Reducedcompe99onatthe100Mbps9er;¢ ReducedbroadbanddeployedintheRDOF.
¢ While100/20MbpswasusedintheCAF-IIAuc9on,inmanyconsumerapplica9ons,10vs. 20 Mbps upload is unlikely to drive differences in the actual usage or serviceofferings–e.g.HDstreaming,videocalls,onlinegaming.
Background: 100/10 Mbps vs. 100/20 Mbps
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¢ TheRDOFUplinkobjec9veisbiasedtowardsoperatorswhodonothavetorelysolelyonCBRSand/orwhichhaveconsiderableotherspectrumresourcestheycanuse(withorwithoutcarrieraggrega9onwithCBRS).� Intra-bandCarrierAggrega9on(PAL–Band48)–channelbandwidthsare10MHzor20MHz;
cancombineuptofive20MHzchannelstogetupto100MHz… � Butanyoneoperatorcanonlyacquire4PALsundertheFCC’sdrabrules,sohavetorelyon
combiningPALswithGAA.
¢ For operators with limited spectrum resources, and that may be consideringdeployment using CBRS only – Band 48, the upstream target will be difficult if notimpossible tomeet inmanycaseswith20MHzofspectrum,andevenpoten9ally incaseswhereacarriercouldacquirethefull40MHzallowed.
¢ AndspecifictoCBRS,thereislimitedequipmentavailable–anumberofthecer9fied
OnGo CPE devices only support Band 48. And there are limited carrier aggrega9onopportuni9esavailable.
RDOF Uplink Service Objective and CBRS
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¢ The tablebelowsummarizesbands supportedbya selec9onofCBRSOnGoCer9fiedCPEdevices:
¢ In total thereare54approvedOnGoenduserdevices.Over50%(28devices)aremobilephones or hotspots, 24% (13 devices) are “modules”. Only four OnGo devices arespecificallytargetedforfixedwirelessdeploymentaswouldberelevanttoRDOF.
¢ ThefourconsumerCPEdevicesforFixedServiceapplica9onsonlysupportBand48.� Thus,theyworkwithlimitedspectrumresources–max40MHzPALs,combinedwithGAA,� By only suppor9ng one band, there are no inter-band carrier aggrega9on op9ons available that
couldbeusedtoincreaseoverallthroughput.¢ Ontheotherhand,thesampleofthreedevicesdesignedformobilesupportabroadsetof
bands,whichprovideformoreop9onstomeetdifferentserviceobjec9ves.¢ Fixedserviceoperatorsdonotnecessarilyhaveaccesstomul9plebands,andinanycasedo
nothavethemobileinfrastructuretosupportthesedevices.
Current CBRS CPE and Spectrum
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¢ Also an important considera9on is that TD-LTE for Band 48 operates with fixedconfigura9onssharingbandwidthbetweenUL&DL:� FrameConfig1has~55%devotedtoDLand40%devotedtoUL� FrameConfig2has~75%devotedtoDLand20%devotedtoUL
¢ Configura9on1providesgreatercapacityforuplink,butmayhaveinsufficientcapacitytomeetthe100MHzdownlinkobjec9ve.
¢ Giventheimportanceofdownlinkspeed,however,Configura9on2istypicallyusedbyvendors as it most closely matches Internet traffic profiles. In this case there is lessspectrumavailableforuplink.� AndoperatorsusingTDDincommonbandinthesameareaneedtocoordinateconfigura9on
tominimizeinterference(andmaximizespectrumalloca9on).¢ The design of the customer premises equipment (CPE) is what dictates uplink
performance. The following analysis provides a basic performance comparisonof twoCBRS CPE devices – NOTE: the analysis is “best case” under ideal condi9ons, notaccoun9ngforspecificsofterrainorgeography.
CBRS Configurations
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¢ ConsideringtwoexamplesofCPE…¢ CPE Device #1 – Zyxel – It is designed for fixed service and supports 573 Mbps
downlink but only15Mbps uplink. This does notmeet CAF-RDOF 20Mbps uplinkrequirement(forAboveBaselineservice).ThedeviceusesBand48only.� Downlink256QAMwith4x4MIMO;Uplinkis64QAMandnoMIMO� ThedeviceusesTDDConfigura9on2–UL:DLra9o2:6–soDLis75%ofthe20MHzchannel.
¢ CPE Device #2 – Inseego – It is designed for mobile service and supports 2 Gbpsdownlink and uplink speeds up to 316Mbps. The device supports Bands 2 (PCS), 4(AWS), 5 (Cellular), 13 (Lower 700), 48 (CBRS), 66 (AWS), with up to 5 x carrieraggrega9on(i.e.5x20MHz).ItalsosupportsmmWavebandsn260andn261–39GHzand28GHz.� Ondownlink ituses4x4MIMO,256QAMand5xcarrieraggrega9on(LTEUECategory20),
Foruplinkituses256QAMandprovidesfor3xcarrieraggrega9on(LTEUECategory13).
CPE and Uplink Performance
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¢ With CPE Device #1 performance, the RDOF Above Baseline service objec9ve obencannotbemet–downlinkanduplink(sinceuplinkislimitedto15Mbpsmaximum).
¢ Even with the more advanced CPE Device #2 performance, with only 20 MHz ofspectrum, theobjec9vesareobennotmet.With40MHzof spectrum, theDevice#2scenariomeetsobjec9vesmoreobenusing50%downlink,50%uplink.
¢ Oneway of improving performance is to increase the number of sites,which in turnincreasesdeploymentcosts.Asshownabove,withmoresitesandthuslowersubscribercountspersite,theperformanceobjec9vesaremetinmorecases,butnotalways.
¢ Toachievethis,however,thenumberofsiteswouldhavetobedoubledortripled–i.e.byincreasingdeploymenttoreducesubscribersfrom20-30persitedownto10persite.
Performance Comparison
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¢ Foranoperator todeployCBRS, there is limitedequipmentavailable– anumberofthecer9fiedOnGodevicesonlysupportBand48.� Therearealsolimitedcarrieraggrega9onopportuni9esavailableforBand48
¢ The FCC objec9ves for 100/20 do not respect the rela9ve downlink vs. uplinkperformanceinpar9cularofCBRSequipment.Ontheotherhand,using75%ofMHztosupportdownlink(CBRSTDDConfigura9on2)wouldbeHermeet100Mbpsobjec9ve,andwouldmorereadilyprovideatleast10Mbpsuplinkinsteadof20Mbps.
¢ Onewayof improvingperformance is to increasethenumberofsites,which inturnincreasesdeploymentcosts.Toachievethis,however,thenumberofsiteswouldhavetobedoubledortripled–makingdeploymentmuchlesseconomic.
¢ TheRDOFUplinkobjec9veisbiasedtowardsoperatorswhodonothavetorelysolelyon CBRS and/or which have other spectrum resources they can apply (mee9ngobjec9veswithcarrieraggrega9on).
¢ IftheUplinkobjec1vewerechangedto10Mbps,thiswouldallowoperatorstomeettheAboveBaselineserviceobjec1veonamuchbroaderbasis.Thiswould increase compe11on for the Above Baseline service objec1ve andincreasedeploymentincurrentlyunderservedandunservedareas.
Conclusions
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