how does wireless internet work
how does wireless internet work

How many of us really understand what goeson when you text your friend across the ocean and they get the ping, almost instantaneously!

Allow me to entertain you with a little thoughtexperiment. When you press “send” on your favouritemessaging app, where’s your message really going? “Into the air,” you’d say, “like radiowaves..” But let’s back up a bit. When you press send on whatsapp, you’reessentially sending instructions to your mobile processor via tiny copper wires on a printedcircuit board in your smartphone. Now, these instructions are essentially electricalimpulses, right? And electrical impulses are just electronsflowing along the potential difference.

How exactly does your message “jump” intothin air from being electron flows in copper wires? At one stage you had a circuit board thatyou could touch and feel (and even smell) and then suddenly you have radio waves inthe invisible part of the spectrum, flying away into thin air at light speed. What’s in between?

What’s in between is this odd looking device:It’s an antenna, which translates to a “pole” in Latin. An antenna is a metal-tongued voodoo devicethat swallows electrical impulses and spits out radio waves. It is silent as the dead, but its screamscan be heard for miles. Specifically, a Wi-Fi antenna like in thepicture, screams at 2.4 GHz (2 billion beats per second!) and spits out waves of length12.5 centimeters.

Unlike visible light, these waves can passthrough walls, and even bend around the corners! How does an antenna produce radio waves? Before we answer this question, let’s takea small detour. Do you remember the recent buzz in pop-scienceabout gravitational waves? They’re basically fluctuations in gravitationalfield, propagating as radiant energy.

Einstein’s general relativity predictedtheir existence a hundred years ago, and we’ve only recently discovered them. Just like gravitational waves, electromagneticwaves are fluctuations in electromagnetic field, propagating as radiant energy. And, not much unlike the story of gravitationalwaves, the existence of invisible electromagnetic waves was predicted by Maxwell’s equationswell before their discovery by Heinrich Hertz!

So to produce radio waves, you need to createfluctuations in electromagnetic field. And to create those fluctuations, you needelectrons moving around in a conductor! The act of radio wave synthesis is a carefullychoreographed, rhythmic dance of electrons in tiny copper wires. Like perturbations in still water that radiateoutward from the point of disturbance, the electron flows in an antenna cause perturbationsin electromagnetic field which radiate out into space like electromagnetic waves. When you press “send” on your favouritemessaging app, your mobile OS sets off a chain of events that ultimately encode the messageas a careful choreography of electron dance.

This dance results in rhythmic ebbs and flowsin the electromagnetic field in the surrounding space, which radiate outward towards a celltower. The receiving antenna on the cell tower feelsthese ebbs and flows on its conducting surface, inducing an electron dance very similar tothe one at the transmitter. This electron dance is again a set of electricimpulses in tiny copper wires, which are decoded by the hardware at the cell tower. The decoded information is then carried onhigh-throughput cables for thousands of miles across countries, continents and even oceansthrough Transatlantic communications cables or some other Submarine communications cables,to a cell tower near your friend across the ocean. From the tower to your friend’s phone isanother wireless jump. And finally, your friend hears the familiarping. How does the phone know where the cell toweris? It doesn’t, and it doesn’t need to! Your phone broadcasts your message in alldirections for anyone to listen to. But don’t worry, your message will be encryptedand only the cell tower can decode your message. How does the cell tower know that the messageis from me?

With every message you transmit, you alsoinclude a code that uniquely identifies your device. That is how the cell tower knows it’s you. How does the cell tower differentiate betweenmessages from different phones? The phones all agree on a protocol to sendmessages to the tower either at different times, different frequencies, different locations,or using different codes.

The best analogy I have for this is that ofa classroom. Imagine a classroom with a 100 students andjust one teacher. Now, if all the students start speaking atonce, the teacher cannot understand any of them. So, they agree on a protocol. If a student wants to speak, they raise theirhand and wait for the teacher to point to them. The student does not speak unless they areasked by the teacher to speak. If multiple students raise their hands atonce, the teacher picks them out one by one so that only one student is speaking at anypoint in time. The cell tower is the teacher, and the devicesare students. While students can speak at different timesto avoid interference, devices can speak at different times, different frequencies ordifferent codes to avoid interference. So, you’re telling me that the majorityof the communication is not really wireless?

Yes! Unless you’re using a Satellite phone, wirelesscommunication is only used for two steps along the road: sender to tower-1, and tower-2 toreceiver. The communication between the cell towershappens through ultra high speed communication cables underground. But, aren’t cables so out of fashion for21st century?

Why not use wireless all the way? Well, the cables we’re talking about herelike the Transatlantic communications cable are definitely very high-tech.

They can carry terabytes of data every second,and do not face the problem of interference nearly as much as their wireless counterparts. Also, you’ll need a lot of satellites tocater to billions of users and their data needs if you want to go wireless all the way. And, launching satellites is really reallyexpensive. That’s it for today guys. We’ll meet you with an another interestingvideo. Till then stay happy stay curious. And ya, don’t forget to like share and subscribethis channel if you haven’t subscribed yet. 

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