Towards Internet Connectivity for Implanted Devicesconferences.sigcomm.org/.../Session08-Paper01-Towards-Vikram-Slide… · Towards Internet Connectivity for Implanted Devices VikramIyer,

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