towards internet connectivity for implanted...
TRANSCRIPT
TowardsInternetConnectivityforImplantedDevices
Vikram Iyer,Vamsi Talla,BryceKelloggShyamGollakota,JoshSmith
Brainimplantsforreanimationoflimbs
Needwirelessconnectivity tomakethispracticalandsafe
BrownUniversity- GuardianNews&MediaLtd
Contactlensesthatmeasurebloodsugar
Google- BusinessComputingWorld
Contactlensesthatmeasurebloodsugar
Canimplanteddevices talk to smartphones?
Conventionalradiosconsumetoomuchpower
Replacingimplantbatteriesrequiressurgery
Problem:CreatingRFsignalsispowerexpensive
Solution:RecycleRFsignalsfromexternaldevices
Interscatter CommunicationRecycleBluetoothsignalstocreateWiFi
CreatesWiFi packetsfor28μW ofpower
OurContributions
• BuildfirstWi-Ficontactlens andbrainimplantproofofconcepts
• Transformwirelesstransmissionsfromonetechnologytoanother,ontheairØ Bluetoothto2-11MbpsWi-FiandZigBee
SystemRequirements
Source
Contactlens
1. Commoditydevicesà Bluetooth/Wi-Fi
2. MinimizeimplantONtimeà Senddataathighrate
3. Sourceisn’tsendingdataàMinimizebandwidth
Receiver
Problem:BluetoothandWiFi aredifferentprotocols
Challenge1:DifferentmodulationFrequencyShiftKeying PhaseShiftKeying
Challenge2:Differentfrequenciesandbandwidth
1) TransformBLEtransmissionsintosingletonesignals
Step2:ReflectthesingletonesignaltocreateourownWi-Fi packets
Step1:TransformBluetoothtransmissionsintosingletone signals
OurApproach
HowdowecreateasingletonefromBluetooth?
flow=0 fhigh =1
Bluetoothusesfrequencyshiftkeying
00
HowdowecreateasingletonefromBluetooth?
0 1 0 1
Bluetoothusesfrequencyshiftkeying
Transmittingall‘0’or‘1’bitscreatesasingletone
HowdowecreateasingletonefromBluetooth?
OriginalPayload:11111
WhitenedPayload:11001
Problem:Bluetoothwhitensthedata
Seed
+Pseudorandombitgenerator
SeedissettothechannelnumberàWhiteningsequenceisconstant
HowdowecreateasingletonefromBluetooth?
OriginalPayload:11111
WhitenedPayload:11001
Solution:Reverseengineerwhiteningsequence
Seed
+Pseudorandombitgenerator
TransformBluetoothtoasingletoneinuserspace
Whiteningsequence
SeedissettothechannelnumberàWhiteningsequenceisconstant
Problem:Bluetoothwhitensthedata
00000
1) TransformBLEtransmissionsintosingletonesignals
Step2:Reflectthesingletonesignaltocreateourown802.11b packets
Step1:TransformBluetoothtransmissionsintosingletone signals
OurApproach
BLE38
Problem:BluetoothandWiFi usedifferentfrequenciesFirst-OrderSolution:UsePassiveWiFi (NSDI‘16)
HowdowecreateWiFi packets?
Smartcontactlens
HowdowecreateWiFi packets?
010
First-OrderSolution:UsePassiveWiFi (NSDI‘16)
Problem:PassiveWiFi createsmirrorcopyoutsideISMband
BLE38
OutsideISMband
2.4GHzISMBand
Wi-FiCH11MirrorCopy
KeyIdea:Cancelmirrorcopyusingtwoswitches
Solution:Firstsinglesidebandbackscatter
++
Implementation
FPGAPrototype:• AlteraCycloneII• Custombackscatterswitch• 2-11Mbps WiFi and250kbpsZigbee
ICImplementation• Verilogbaseband,RFswitch,&customPLL• TSMC65nmLPProcess• 28µWat2Mbps
HowwellcanwecreateasingletonefromBluetooth?
Moto360Transmission
SamsungGalaxyS5
-20
-40
-60
-80
-20
-40
-60
-80
Power(d
Bm)
2.4152.422.4252.432.4352.44Frequency(GHz)
2.4152.422.4252.432.4352.44Frequency(GHz)
Power(d
Bm)
Whatistherangeofoursystem?
d1 =1ft
d2
Whatistherangeofoursystem?
-50
-60
-70
-80
-90
0 10 20 30 40 50 60 70 80 90
Wi-FiR
SSI(dB
m)
DistancebetweenbackscatterdeviceandWi-Fireceiver(ft)
10dBm4dBm0dBm
ProofofConceptApplications
ContactLensPrototype
BluetoothTX
Wi-FiRX
BMIPrototype
BluetoothTX
Wi-FiRX
Conclusion
• Transformwirelesstransmissionsfromonetechnologytoanother,ontheairØ Bluetoothto2-11MbpsWi-FiandZigBee
• Opensupnewopportunities forimplanteddevices
interscatter.cs.washington.edu