Adaptive Beam AntennasAdaptive Beam Antennas

Omar BakrOmar Bakr

UC Berkeley/ Computer ScienceUC Berkeley/ Computer Science

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ScenarioScenario

CellTower

Backhaul link

Rural VillagesCan we these remote areas to the Internetin a cost effective way?

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Why Adaptive Beam FormingWhy Adaptive Beam Forming Tower dominates cost (both fixed and ongoing)Tower dominates cost (both fixed and ongoing)

Considerably simplifies tower design, installation, maintenanceConsiderably simplifies tower design, installation, maintenance

Possibly eliminate the tower all together (beyond the scope of this Possibly eliminate the tower all together (beyond the scope of this project)project)

Challenges: optimal steering on both ends of a variable long distance Challenges: optimal steering on both ends of a variable long distance link is very hard, especially when relying on cheap hardwarelink is very hard, especially when relying on cheap hardware

Optimal system performance (high data-rate, low energy Optimal system performance (high data-rate, low energy consumption) requires intelligent, adaptive software supportconsumption) requires intelligent, adaptive software support

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Antenna System ConceptAntenna System Concept Low-cost adaptive beam steering antennaLow-cost adaptive beam steering antenna

For Wifi: 802.11b, maybe 802.11a/b/g/nFor Wifi: 802.11b, maybe 802.11a/b/g/n

Where cost(antenna) < cost(access point)Where cost(antenna) < cost(access point)

Expect cost(antenna) < $50Expect cost(antenna) < $50

Software controllable antennaSoftware controllable antenna

Enable continuous low-frequency channel optimizationsEnable continuous low-frequency channel optimizations

Simplify deployment; increase performance and robustness Simplify deployment; increase performance and robustness

Motivation and specialization from ICT4B contextMotivation and specialization from ICT4B context

1-60km point-to-point links => 25-35dBi antenna gain1-60km point-to-point links => 25-35dBi antenna gain

Standard 802.11a/b/g/n physical layer; higher maybe non-stdStandard 802.11a/b/g/n physical layer; higher maybe non-std

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System Design SpaceSystem Design Space

Four classes of antennas can be controlled electronicallyFour classes of antennas can be controlled electronically

ElectromechanicalElectromechanical

Phased arrayPhased array

Active integratedActive integrated

Switched parasiticSwitched parasitic

Two of these are not relevant for usTwo of these are not relevant for us

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System ParametersSystem Parameters ConfigurationConfiguration

BB half power beamwidth half power beamwidth

AA dynamic azimuthal rangedynamic azimuthal range

+/- (A/2) right/left+/- (A/2) right/left

aa azimuthal precisionazimuthal precision

(A/a overlapping sectors each B degrees wide)(A/a overlapping sectors each B degrees wide)

EE dynamic elevation rangedynamic elevation range

+/- (E/2) above/below+/- (E/2) above/below

ee elevation precisionelevation precision

(E/e overlapping elevation sectors each B degree tall(E/e overlapping elevation sectors each B degree tall

pp polarizationpolarization

ff frequencyfrequency

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Phase ArraysPhase Arrays

PA

LNA

PA

LNA

PA

LNA

PA

LNA

Transmitter

Receiver Controller

Phasor Array

Dupx

Dupx

Dupx

Dupx

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Switched Parasitic AntennasSwitched Parasitic Antennas A single active antenna surrounded by a system of passive scatters A single active antenna surrounded by a system of passive scatters

with controllable reactive loadswith controllable reactive loads

Varactor diodes can serve as the reactive loads in passive scatters; Varactor diodes can serve as the reactive loads in passive scatters; use reverse bias magnitudes to control diode depletion capacitances use reverse bias magnitudes to control diode depletion capacitances

Control requires DACs for analog reverse bias and RF chokes to Control requires DACs for analog reverse bias and RF chokes to isolate the low-frequency control circuits from the diodesisolate the low-frequency control circuits from the diodes

An Antenna Control Unit implements the beam forming algorithm that An Antenna Control Unit implements the beam forming algorithm that optimizes channel characteristics by adjusting the loadsoptimizes channel characteristics by adjusting the loads

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Russia Prototype #1Russia Prototype #1

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Future TopicsFuture Topics Multi-band antenna system for 802.11a/b/gMulti-band antenna system for 802.11a/b/g

dual band elements; simultaneous send/receive on different bandsdual band elements; simultaneous send/receive on different bands

Eliminate interference among co-located antennasEliminate interference among co-located antennas enable dense population of towers with antennas for different links or sectorsenable dense population of towers with antennas for different links or sectors

16 sector x 360 degree low-gain system for indoor wifi16 sector x 360 degree low-gain system for indoor wifi can compact variant be demonstrated for localization applicationscan compact variant be demonstrated for localization applications

Hybrid analog-digital phase shifting system with GolanHybrid analog-digital phase shifting system with Golan Use PCI express cards to demonstrate unique capabilities and valueUse PCI express cards to demonstrate unique capabilities and value

2.4 to 3.5 Ghz up-down frequency shifting system2.4 to 3.5 Ghz up-down frequency shifting system stake our claim to this currently unused bay area spectrastake our claim to this currently unused bay area spectra

System with two independently steerable beams?System with two independently steerable beams?

Extreme precision, 1-lambda azimuth control at 1kmExtreme precision, 1-lambda azimuth control at 1km

Adaptive antenna systems for WiMax terminalsAdaptive antenna systems for WiMax terminals

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Russia: People and PlacesRussia: People and Places

Prof Alexey Umnov, Nizhny Novgorod State University,Prof Alexey Umnov, Nizhny Novgorod State University,

Maxim Suralev (NNSU and Intel Intern), and co.Maxim Suralev (NNSU and Intel Intern), and co.