Wireless Communication Out of Thin Air

Presented By

Annette Maria John(14MCE0017)

Subhajit Chatterjee(14MCE0018)

Naumi Krishna K Panicker(14MCE0019)

Introduction

We're one step closer to a true Internet of things with the development of new technology that lets devices communicate with each other using existing TV and Wi-Fi signals.

The most impressive part? They don't require batteries.

The New Technology, The New Future

A team of researchers from the University of Washington just unveiled a new communication technique that doesn't require any human attention.

Known as "AMBIENT BACKSCATTER", this technology literally creates a network out of thin air, and the devices can go anywhere.

Ambient backscatter??

Harvesting Power From Thin Air.

Ambient Backscatter transforms existing wireless signals into both a source of power and a communication medium. It enables two battery-free devices to communicate by backscattering existing wireless signals.

How it works??

Two devices communicate with each other by reflecting the existing signals to exchange information. The researchers built small, battery-free devices with antennas that can detect, harness and reflect a TV signal, which then is picked up by other similar devices.

Design Challenges

Mainly 3 challenges are faced: The ambient signals are random and

uncontrollable. The receiver has to decode these signals on a

battery-free device which significantly limits the design space by placing a severe constraint on the power requirements of the device.

Since there is no centralized controller to coordinate communications, these devices need to operate a distributed multiple access protocol and develop functionalities like carrier sense.

Block Diagram

Switch Modulates the impedance of the antenna and causes a change in the amount of energy reflected by the antenna Input 0 Transistor is off, impedences are matched Very little of the signal reflects Input 1 Transistor is on Larger scattered signal amplitude

Ambient Backscattering Transmitter

Samples the analog signal Performs demodulation Decoding in the digital domain Received samples- combination of the wideband TV

signals and the backscattered signals

Ambient Backscattering Receiver

Demodulator Circuit

Envelope detection and Averaging circuit Smoothens out the natural variations in the TV

signal Compute-Threshold circuit Produces a threshold between the two levels Comparator Compares the average envelope signal to the

threshold

Applications

Everyday objects could be enabled with battery-free tags to communicate with each other.

• Smart Card Application• Grocery Store Application

Passive cards can communicate with each other

It’s applications are

money transfer between credit cards

paying bills to implement a digital

paper technology

Smart Card Application

Grocery Store Application

Ambient backscatter can also be used to tell when an item is missing or out of place on a shelf in a grocery

store.

Smart sensors could be placed permanently inside

nearly any structure.

Text messages and emails

Smart phones

Other Applications

Wearable computing, smart homes and self-

sustaining sensor networks.

Researchers are trying to advance the capacity and

increase the range of this device

Future Scope

Pros & Cons Pros Consmore power-efficient Range is very little does not require a dedicated power infrastructure maintenance cost is negligible

interference with TV Receivers is negligible

Conclusion

This technology can really enables us to put sensors on everything, and to turn every normal object into a smart object that can interact with every other object and computer on the internet.

You’ve seen what happens when billions of people are persistently online thanks to mobile phones; now imagine what would happen if you added billions of traffic signals, cars, supermarket shelves, refrigerators, and air conditioning systems to the mix.

THANK YOU