User's Manual
Table Of Contents
- Understanding Silver Spring Networks Access Points
- Contents
- 1 About Access Points
- Overview
- Features
- AP Product Description
- Battery Backups
- Read Storage
- Power Requirements
- Rebooting or Recycling APs
- Standards Compliance
- Cellular Modem
- Addressing Schemes
- Specifications
- European Union Compliance
- Maintenance Procedures
- Surge Protection
- Redundant WAN Option
- Mounting Options
- WAN Options
- Throughput Performance
- Responding to a WAN Failure
- Multicast / Unicast Communications
- Networking
- Address Management
- Administration
- Configuration
- 2 FCC and Government Guidelines
- Index
Understanding Silver Spring Networks Access Points 1 About Access Points
Understanding Silver Spring Networks Access Points 4 March 2013 Silver Spring Networks 13
ThedesignruleforAccessPointtoRFdevicesis1to5,000.Atthisratio,themaximumdata
throughputrequiredfromaWANsolutionis40kbpsperAccessPoint.
Basedonreal‐worlddataonanetworkofthissize,theaveragewirelessspeedismeasuredat
2.6Mbpsdownstreamand
700Kbpsupstream,whichiswellinexcessofrequirements.
Thebackhaulisfairlyinsensitivetolatency(that is,inremotelocations,SilverSpringalready
provensuccessfulconnectionusingsatelliteradioswhichhavea~1.5sRTT‐orRoundTrip
Time).
SilverSpringrecommendsthatthenetworkdesignforaparticulardeploymentlimit
exposure
tosinglepointsoffailureandproactivelydesignforredundancybyallowingeach
RFdevicetobereachedfrommorethanoneAccessPoint.Inallbutruraldensities,having
upto5,000RFdevicesperAPgenerallyresultsinmostRFdevicesbeingabletoreachmore
thanone
AccessPoint.
Throughput Performance
Typicaldatapacketsizesobserved inSmartGridsys temsisbetween150bytesforDAor
othersimplecommandandcontrolapplications.AnormalHCMandAMImeterreadpacket
isapproximately350bytesincludingfullmeasurementintervals,eventlogs,and
instantaneousregisterreads.At100Kbps(10bytes/ms),
deliveryof150bytepacketsoccurs
at10fulltransactionspersecond.
ThelargerAMI/HCMpacketsaredeliveredat3‐5transactionspersecond.Thesearetypical
observedratesanditshouldbementionedthatforreliabilityreasonsalltransactionsare
completelyacknowledgedfour‐wayconfirmedevents.
Thoughfinaldata
isnotavailable,raisingon‐airdataratesfrom100Kbpsto300Kbpswill
roughlydoublethePPSratesattheaggregationpoints(AccessPoints).Thismovesthedaily
capacityofanAccessPointfromapproximately400,000transactionsperdaytonearlya
million.
Thebandwidthbeingfedtothe
WANsideoftheAccessPointisdeterminedbywhat
backhaulisbeingused.
WiththeAccessPointbeingarouterandnotacol lector,dataisconstantlybeingtransmitted
throughtheWAN,eliminatingtheneedtostoredataforlatertransmission(Storeand
Forward).TheAccessPoint,using100Kbpson
theNANside,aggregates3000‐5000meters,
bridges,orotherRFdevices,whileprocessingapproximately5transactionspersecondand
deliveringupwardsof500,000transactionsperdaytothebackoffice.
TherawthroughputintheRFNANintheSilverSpringsmartgridsolutionis100Kbps
node‐to‐node.
Thismeansthatbetweeneachdevice,thereis100Kbpsofavailable
bandwidth.Onaverage,theamountoftrafficisrelativelylowwithrespecttotheamountof
availablebandwidth.
Figure4illustratesdatacollectedfromalivecustomernetworkoveraperiodofoneweek.
Asshown,theaveragebandwidthconsumedbyAdvancedMetering trafficisapproximately