Demystifying WiFi

its twenty first birthday not long ago. The original WiFi standard was released in nine seven, but the development of WiFi stretches back further than that, and I thought it might be interesting to trace that history and get to know more about the tech that lets us set up a local coffee shop situation, you know, to catch up on emails. How, how did that come to pass, and how does it actually work? Well. Decades before there was

a WiFi standard, there was a Lohan net. Back in the late nineteen sixties, computer scientists and students at the University of Hawaii. We're trying to come up with a way that would let students on the various Hawaiian islands communicate with the main frame computer on the Oahu campus at the university. Their work was concurrent with the work of BBN, a company that was working on our bonnet and our ponette, you may remember, was the predecessor to

the Internet. The purpose of our ponet was to find out ways to connect remote computers together, remote computers that were working on different computer architectures, and have a way that they can meaningfully communicate with each other. Well, this was happening around the same time. Now, one thing the group wanted to do was take advantage of a special

way to send data between computers called packet switching. M I T had developed packet switching back in nineteen sixty five, so it was still a relatively new technology when the folks over at the University of Why You decided to try and create their own Aloha net. So what exactly is packet switching and why is it so important and how networks send information? Well, let's say you want to transfer a large file from one computer to another, a

really big one. Let's say that it's maybe several gigabytes in size, which today is a pretty big file. Back in the days of nine that would have been an unimaginably huge file. But let's stick with it. Now. Let's say you're trying to send that file over a network. The bandwidth of that network might limit how large a file you'd be able to send. In other words, your connections, your routers, your switches, your buses, if they have a limit on how much information can pass through at one time,

that might mean that you can't send that file. It's just too big to fit through the pipes. If you want to have kind of a poor analogy, but a physical analogy, imagine that you have a very narrow road and you're driving a really wide truck, and you're really wide truck is actually too wide for the narrow road. Well, looks like you're gonna have to find another way to get your truck to the other side of that road.

That's kind of what I'm talking about here. So packet switching was a way to make this more manageable, to allow files to transfer across a network in a way that did not overly stress the infrastructure. Essentially, packet switching works by dividing files up into chunks of data called packets. You can think of them as like envelopes that have letters inside of them, and each letter is part of

a file that you're sending across the Internet. Packets contain a little extra information in them in addition to the file itself. That information includes data about the computer that was sending the file the computer that's supposed to receive the file, so kind of like the return address and the send address, those two things would be included, and also how that particular chunk of data fits in with

the rest of the information that's being sent. So you can also think of it as sort of like instructions on how to put a puzzle back together. So if I go with the mail analogy, as in like postal mail, every single piece of information is a piece of a puzzle, and with that piece of a puzzle, I include a little bit of instructions about where that piece fits. I might say this piece is the bottom right corner of the puzzle, and then the envelope has the address that

I'm sending from and the address I'm sending to. Well, that's kind of like a packet of data. In packet switching, you send these smaller, more manageable chunks of data across a network. The chunks may or may not follow the same pathway to get to their destination. They may not all go through the exact same nodes across the Internet.

The neat thing is they can all split up and take different pathways, and typically you have duplicate packets journeying to the destination to help ensure that the full file arrives where it needs to go. Otherwise the file will be corrupt because it will be missing a piece of the puzzle. Once the packets get to the right computer, they get reassembled into whatever the original file was, whether it's a text file, an image video, whatever it might be.

The team at the University of Hawaii wanted to use packet switching technology coupled with radio transmissions in order to send information from the main frame and to receive information from students across the island chain. They decided to create a system that would transmit information using radio signals that

were in the ultra high frequency or UHF range. UHF, apart from being a hilarious weird Al Yankovic movie, is a range of radio signals that fall into the spectrum that at the low end is at three hundred mega hurts and at the upper end is at three giga hurts. Now it hurts is a unit that refers to one cycle per second. I've talked about this recently, but it's

always good to go over this again. Now imagine that a radio wave is a long sign wave with smooth, even peaks and valleys, and they just repeat over and over and over again. Now, if you were to take an arbitrary point, such as the peak of the wave, and measure it to the next peak over, you would have one wavelength of that radio wave. Radio waves travel at the speed of light, regardless of wavelength, if it's

a short wavelength or a long wavelength. So if you know how long a wavelength is for a radio wave, you know how many radio waves will pass a given point in space every second, because you already know the speed at which they will travel. A three hundred mega Hurts radio wave will have three hundred million waves pass through a given point in space per second. A three giga Hurts radio wave will have three billion radio waves

pass that same point per second. The three gig Hurts waves clearly have to be smaller than the mega Hurts ones because they're all traveling at the same speed. So the only way you can cram more wavelengths past the

point per second is by decreasing the wavelength. The radio spectrum as a whole, by the way, starts all the way down at three hurts meaning only three extremely long radio waves would pass a given point in space every second, and it goes all the way up to three terra hurts, which is equivalent to three thousand giga hurts or three thousand billion cycles per second. So while UHF stands for ultra high frequency, it's nowhere near the top of the spectrum.

Aloha net relied on to such frequencies in the UHF range. One frequency was used for outgoing signals from the main frame to the other computers, so the main computer would send signals out over one frequency to students, but the other frequency was used by the other computers to send messages back to the main frame, so the students machines would use a different frequency. So you had kind of two channels in a way. You had the outgoing and

the incoming. But this created a possible problem. There could come an instance in which more than one computer was trying to communicate with the main frame at the same time, and when that happened, the signals were said to quote unquote collide with one another. It's sort of like trying to have multiple people talk over a single radio channel. Only one person can speak at a time. If multiple

people try it's just a mess. So alohan Net adopted a strategy in which the main frame would send out a received signal whenever an incoming message came in without a collision. It was essentially saying, I am confirming that I got your message, and that would tell the sending computer that the message got through, and if the sending computer did not get such a response, it would attempt to send the packets of data again at a randomly

determined time interval. That random interval was meant to decrease the possibility that another collision would occur because obviously more than one computer is involved in this, and if both computers tried to send the exact same data packets at the same time intervals over and over again, you're just gonna keep getting collisions. This time, there would be the hope that there would be no collisions because you would have this somewhat random time interval that is spacing things

out a little bit. Now. In its original configuration, alohan that was not terribly efficient. It had a throughput rate of just eighteen percent and most of the bandwidth went unused, and so the team needed to come up with a fix. First, they tried the old time sharing route. Time sharing is when you have several terminals connected to a centralized computer.

The computer can only work on one set of instructions at a time, and so users have to wait a turn to access the computers processing power and memory and etcetera. But computers work really fast and so frequently it would feel like you were working on a mainframe in real time at the same time as everybody else, though in fact the computer is actually rushing to complete one set

of instructions before starting on the next one. The problem with time sharing over radio network was that the computers had to follow a schedule of when they could send packets, so if it wasn't their time to send a packet, they had to wait and so and meant that there were wasted cycles since sometimes the computer had nothing to send and so those scheduled transmission times would go unused. However, this did increase the throughput rate for a Looha net,

so it improved things a little bit. The team decided to try a different approach to improve the system further, and they designed instructions so that client machines, the ones that are sending request to the centralized computer, would monitor the traffic on the radio channel to determine when the channel was free. So essentially they're listening for the quiet spots, and then the client machine would send packets over that

radio channel. The packets were actually smaller at this point, which would allow for more gaps between packets, and that would allow other computers to slip other packets in. So while the messages appear to be consistent and continuous, in fact it's a bunch of tiny little puzzle pieces, and occasionally there's enough of a gap for other puzzle pieces to sneak in, and the centralized computer would just sort

everything based upon the meta information on the packets. This approach got the name Carrier Sense Multiple Access or c s m A. The system continued to monitor collisions as well, so it's full name was c s m A DASH c D or Carrier Since Multiple Access with Collision Detection. Now I've got more to say about the evolution toward WiFi, but before I go further, let's take a quick break

to thank our sponsor Aloha. Nette was up and running by nineteen seventy one, but it would still be more than twenty years before we'd see the first WiFi standard get unveiled. He could be fourteen years before I have another big moment to talk about in the evolution toward WiFi. That moment happened in nineteen five when the United States Federal Communications Commission, or FCC changed the rules about the

radio spectrum. Every country has rules about which frequency bands in the radio spectrum may be used for specific applications. For example, in the United States, AM radio has all frequencies between five thirty five killer hurts and one thousand, six hundred five killer hurts. No other technology is allowed to use those radio frequencies. This prevents various technologies from

interfering with one another. If you didn't have restrictions on who could use which frequency, then whatever frequency was the strongest had the greatest UH energy behind it in any given area would win out and it would be chaos. And so the United States divvied up the radio spectrum for specific uses, which included not only communications technology but also stuff like microwave ovens. Say what, and by the way,

this is not just the US. Other countries also have done this, But it's because technology like microwave ovens can generate radio frequencies of their own, not to communicate, but that can be a byproduct of their operations. So the United States FCC mandated that manufacturers of microwaves and other technologies that create these radio waves make sure their products only generated radio frequencies within specific bands in order to

avoid creating interference for other technology. So it's not like the US specifically said, hey, let's set aside the slice of radio frequency spectrum so that microwaves can talk to one another. In staid, they said, hey, let's make sure all microwave oven manufacturers be certain that their ovens only generate radio frequencies in this slice so that the ovens don't interfere with communications equipment. In other words, they set aside a certain slice of the radio spectrum and said

this is your playground. You can create stuff that creates radio frequencies in this range, and that shouldn't mess up anything that's on either side of that frequency range. These bands, the ones set aside for equipment that can generate radio waves but aren't necessarily communication tech, are called I S M bands. The I s M stands for Industrial, Scientific,

and Medical. These bands cover several different separate groups of frequencies, but two of them include the two point four giga Hurts to two point five gig Hurts band and the five point seven to five gig Hurts to five point eight seven five giga Hurts bands. These are going to

be very important for our discussions on WiFi. Now again we look at five, when the FCC decided it would open up three I s M bands to unlicensed use that would in flude the two point four giga Hurts and the five point seven to five gig Hurts bands. Unlicensed use required a couple of technological allowances. One was that the transmitters would have to be very low power

in the one watt range. Another was that gadgets making use of that frequency would need a high tolerance to interference since other devices were still going to be giving off radio waves at those frequencies. Essentially, what the FCC was saying is, you can develop technologies that can work on these ranges as long as they aren't so powerful that they're going to interfere with other technologies, and you do it with the understanding that there's already stuff out

there that's generating radio waves in these frequencies. So whatever you create needs to be done in such a way that it can tolerate that This decision in set the foundation for WiFi, which still would not debut for another decade, but that didn't mean there weren't people working on the idea in the meantime. One of those people was Vic Hayes. Hayes had joined the NCR Corporation in the nineteen seventies.

In CR, which originally stood for National Cash Register, had been involved in various technologies since its founding in the late nineteenth century. In CR's goal was to create a standard that the company could then use in its own systems. The idea was that the standard would allow companies to create systems that connected devices like front end retail equipment such as cash registers and back end mainframe systems and using radio waves instead of cables or other clunky methodologies.

And they didn't want to go a proprietary route. They wanted to create a standard that would work so that various O E M companies could create products that used it. Hayes had done some work and authoring standards for data communications as part of his job previously, and NCR was interested in finding an unlicensed use for the two point for giga hurts I s M band, n c R and a T and T had developed a working predecessor to the would essentially evolve into WiFi in nine, and

that was called wave land. They submitted the design of this wireless protocol to the I E E E A O two LAND slash MAN Standards Committee. Land, by the way, stands for local Area network and MAN for a Municipality Area network or Municipal Area network. This led to the need to form a new working group within that committee, The eight O two Committee to Create a Standard for Wireless Networking Communication NCR chose Hayes to head up a

working group to that effect in nine. The working groups designation was a O two point eleven and their goal was to create a standard for wireless local area networks. Now, a local area network is pretty self explanatory. It's a network of computing devices that are locally connected to one another, generally contained within a building or maybe a campus of buildings.

The devices can intercommunicate with one another. A LAND can be but doesn't have to be connected to wider networks like the Internet, and in the old days, the only way you could set up a LAND was to actually have physical connections between all the different machines and some sort of hub, but NCR wanted to do away with those physical connectors and create a standard that manufacturers could use to build in wireless communication capabilities directly into their products.

Hayes had some radio communications background and had previous experience helping create communication standards, but still wasn't sure he was the right man for the job. As it turned out, he absolutely was. He gathered a group of experts together and they began to debate what needed to go into the standard, and the first big argument was over two

different modulation strategies, frequency hopping or direct sequence. Both of those techniques are meant to use a larger bandwidth for transmission than what would otherwise be necessary for the specific type of data you're sending back and forth. Frequency hopping spread spectrum or f h s S divides a large bandwidth into parallel, narrow channels there are large enough to

hold the data in question. If we go back to talking about vehicles and roads, this would be saying, let's imagine that you have a really, really wide highway I'm talking twenty lanes wide. Uh, and at first you don't have any lanes painted in there, it's just an enormous road. Well, you could try and use it that way. But frequency hopping would allow you to create narrower lanes, lanes that are wide enough for a vehicle, so that you could have twenty vehicles traveling on there if they all were

sticking to their own lanes. That's kind of the idea behind frequency hopping. The system sends data in a semi random way to one of those channels, but that means the other channels go unused in the process, and because only one channel is in use at any given time, you're technically wasting bandwidth equal to the size of the channel multiplied by the number of channels minus one channel, because you're already using one. So this would be like saying, yeah,

you have a highway, it's twenty lanes wide. You've painted these lanes in there, so you can randomly choose a lane between one and twenty and you're fine, But that means the other nineteen lanes are going unused. It's not an efficient use of space. That was the argument against

this strategy. Uh, that's obviously inefficient, but it was also technically easier to do, and so about half the working group wanted to pursue frequency hopping as the modulation methodology of choice because while it wasn't efficient, it was easier to implement. Direct sequence spread spectrum or d S S S introduces pseudo random noise into the signal it sins in order to change the phase of the signal itself.

This creates the digital equivalent of static. It would seem to be meaningless information when you received it, but if you knew which pseudo random sequence was used to create the phase shift, you could reverse that whole process. You could d spread the static and extract the meaningful information out of it. D S S S is more challenging to implement than f H S S, but it also is more robust, and so the other half of the

group wanted to follow that idea. Both of those methodologies would allow for multiple devices to communicate across a band of frequencies without interfering with one another, and the I E E E Rules stated that in order to adopt a strategy, you had to secure the support of at least seventy of the working group, but each method had about of the support. The only solution was to create a system that could support both modulation strategies, and so

that's what the group decided to do. I'll wrap up the history of WiFi and give all a low down on what the different variations mean in just a second. But first let's take another their quick break to thank our sponsor. While the working group began to hash out the standards that would become fundamental to WiFi, a group of engineers, astronauts and astronomers were developing a technique that

would become just as important. Vick Hayes, whom I mentioned earlier, is sometimes called the father of WiFi, but another man, John O'Sullivan, also gets that title on occasion. O'Sullivan is an electrical engineer, and he focused on radio astronomy. He led a team that developed a way to reduce multi path interference of radio signals, something that was absolutely necessary if you want to have a smooth experience with a

wireless local area network. His team's work would receive a patent credited to the Commonwealth Scientific and Industrial Research Organization or c s i r O, which is an Australian federal government agency. The really funny thing to me is that this research was originally part of an experiment to try and detect expanding many black holes. That experiment failed, but the technique would end up changing the world once

incorporated into WiFi. Meanwhile, back in the eight O two point eleven Working Group, the standard was getting closer to becoming a real thing. The very first version of the protocol was unveiled in It had a maximum download speed of two megabits per second, which is excruciating lee slow these days, and that was only if you could use the D S S S approach. Remember, it involved both

the direct spread and the frequency hopping. If you used frequency hopping, you topped out at one megabit per second. That didn't exactly cause everyone to throw their cables out their respective windows in a fit of joy, but it was progress. In ninet, the Working Group released a new protocol, and this one was called eight O two dot eleven B. It also used D S S S and the two point for a gigahertz band, but it was able to

boost speeds up to eleven megabits per second. While this was the second protocol released by the group, it was the first to be widely adopted as a wireless local area network standard. Chances are, if you were an early adopter of wireless technology, this was the standard your computer was using, as it was the first that time that manufacturers actually embraced this technology when they started making network adapters.

Later on, the functionality would be built directly onto laptop motherboards instead of having to get an adapter that you would plug into your laptop. But this was still pretty darn slow compared to wired connections. A little later in nine, a new methodology launched. It was called eight O two point one one A. And yes, these designations are getting awfully confusing because the naming standard jumps around a bit.

We just talked about AT two point eleven B and the original one was just called AT two point eleven and now we're talking about ATO two point eleven A. This one had a couple of major differences from the earlier versions. First, it worked on a different band of frequencies.

Instead of using two point four giga hurts, at two point eleven A relied on five giga hurts, And that meant the AT two point eleven A standard was not compatible with the earlier ones because it was using a totally different range of frequencies for communications, so you could not use a Dot eleven A device with a Dot eleven B device. They talked on different radio frequencies so they could not communicate with each other, but it was also faster, with the top speed of around fifty four

megabits per second. In addition, it relied on something called orthogonal frequency division multiplexing or o f d M. Now, this is a way to in code data across multiple carrier frequencies, and maybe someday I'll try to tackle that concept in a full episode, but it gets super technical, so I'm going to leave it for now because I'm running out of time and we still have a couple

of versions of WiFi we have to touch upon. The next one is at two point eleven G. That standard debuted in two thousand three, and it uses the two point for giga Hurts radio band, so back to two point four but like at two point eleven A, it also used o f d M, and that would give point eleven G a max speed of fifty four megabits

per second. And because it communicates on the two point four giga Hurts range, it is compatible with eight to two point eleven B, and so a lot of the equipment you could buy, such as a wireless router, would have the designation of eight to two point eleven B slash G, meaning it could operate across both standards. Also, you should know that communication can only go as fast

as the slowest component involved in the communication. So if you had an AT two point eleven B device communicating with an AT two point eleven G device, you could only hit speeds about to eleven megabits per second because that was the top speed limit for B. So it's kind of like a a chain is only as strong as its weakest link. The connections are only as fast as their slowest point. In two thousand nine, we got

at two point eleven IN. This standard allowed for the use of multiple antennas when transmitting information, which increased speeds

up to four hundred fifty megabits per second. What's more, the eleven N standard could operate across both two point four and five giga hurts bands, meaning it could also communicate with all the older standards like AT two point eleven B, slash G and at two point eleven A. Then in two thousand twelve we got at two point eleven A C and yes I am crying, thanks for asking. This standard operates in the five giga hurts range and has ends for speeds in the gigabit realm, which is

wicked fast. It's also really useful if you've got a lot of machines connected within that single wireless land, because you've got a lot of bandwidth to play with. Now, at ce seen some companies showed off devices that are using a new version of WiFi has not yet had an official release. It's called eight O two point eleven a X, and the devices at ce S were reported to have a top data transmission speed of eleven gigabits

per second, which is really wicked fast. It can operate in both the two point four and five giga Hurts bands, and it should launch sometime in two thousand nineteen officially. Now, there are other versions of the WiFi standard that don't use the two point four or five giga Hurts ranges. They tend to be for other types of technologies than

mobile devices and computers. They could be for something like an in vehicle network, for example, And I didn't cover them because you're not likely to work with them yourself in an average setting. But I hope this gives you a little more information about WiFi. Maybe in a future episode, I'll dive into deeper detail of exactly how WiFi works.

But you have a general idea it's all about radio frequencies, mostly in the two point four gig hurts or five giga hurts five point seven to five gig hurts range, to be specific, and that it involves various modulation techniques so that multiple devices can communicate with a centralized router or hub in order to send information with to each

other and also to the Internet at large. So it's been a very useful technology, one that has transformed our world in meaningful and difficult to anticipate ways, and I

suspect the that will continue to be the case. In fact, we may even see wireless technologies supersed wired ones to the point where people who are using high speed connections for their jobs or for stuff like high end gaming will choose to go wireless rather than wired, because we may eventually get to the point where it's just faster, it's just less latency, higher data throughput rates. If that happens, it's really a game changer. I hope you guys enjoyed

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