How does 5G work? | A RARE look inside the 5G testbed facility @IITM | BP2B Labcast Ep 1

a Jio telecom user and a Airtel telecom user. This happens with a periodicity of about 0.5 milliseconds. So this is our first, uh, fi- call on the indigenous 5G system from a commercial 5G phone. Here, this core network, we manage the traffic from all the deployments in the IIT Madras campus deploy.

As far as I know, it took about four years-

Yeah

... to finally finish up the test bed.

Correct. [upbeat music] Hi, and welcome to The Best Place To Build Labcast. Today, in the very first episode, we're gonna be visiting the 5G testbed facility of IIT Madras, the place where India's first-ever 5G phone call was made. Stay tuned, because we are gonna look at what they are building, how do they do it, and what are they building now that 5G is everywhere? Before we see what happens there, let's first understand how 5G transmission works. See, whenever you try to connect, your phone sends and receives radio signals to an antenna, the same things you see around you on towers. It processes these signals into digital signals and sends them to a baseband unit to handle the connection request. The BBU then forwards your traffic into the 5G core, which authenticates you, manages mobility, and routes your data to the Internet or another user. And now, let's have a look at it in more detail with Jeeva from the lab. So this radio unit is responsible for transmitting and receiving the radio signals. So this is the component that is actually exposed, and when our mobile phone actually connects to something, it sends the radio waves. The number of radio elements have significantly increased. Typical 4G deployments will have one to four antenna elements, but in a 5G, if you see, there'll be 16, 32, and 64 antenna elements that are present over there.

So why, why do you need such complexity? Why do you need to keep adding more antenna elements?

So when I speak to you, I look at you and speak, but when a radio unit is talking to you, it doesn't know exactly where you are, or it cannot rotate itself. So what it does is, a typical radio unit, it'll broadcast the signal in all the directions. When I have multiple antennas, it is possible for me to direct my energy into the, uh, direction where a user is present, where it is required, so that I don't waste the energy which is going on other directions. Having said that, the catch is that every antenna element here has to be fine-tuned and calibrated, and this is not a simple calibration process. That, uh... This involves a lot of algorithms. And this radio unit, where does it sit? Somewhere on a tall tower, so it is not possible for anyone to actually go over there and calibrate it every time. So this has to happen-

And how often do you need to calibrate it?

So it depends on the algorithm, and very important part about calibration is it should not disturb an actual transmission and reception that is happening. We decide that as well based on the changing channel scenarios, where do you deploy it, how often the scenario is changing. It depends on the varying temperature as well, and aging as well... lot of parameters.