WEBVTT - Demystifying WiFi 0:00:04.160 --> 0:00:07.160 Get in touch with technology with tech Stuff from how 0:00:07.240 --> 0:00:13.920 stuff works dot com. Hey there, and welcome to tech Stuff. 0:00:13.960 --> 0:00:17.320 I'm your host, Jonathan Strickland. I'm an executive producer at 0:00:17.320 --> 0:00:21.159 how Stuff Works in I love all things tech, and 0:00:21.320 --> 0:00:26.840 one of the most pervasive modern technologies today is WiFi, 0:00:27.160 --> 0:00:30.880 which is fascinating since as a standard, it just had 0:00:30.880 --> 0:00:34.040 its twenty first birthday not long ago. The original WiFi 0:00:34.080 --> 0:00:38.800 standard was released in nine seven, but the development of 0:00:38.880 --> 0:00:41.640 WiFi stretches back further than that, and I thought it 0:00:41.760 --> 0:00:44.440 might be interesting to trace that history and get to 0:00:44.479 --> 0:00:47.040 know more about the tech that lets us set up 0:00:47.360 --> 0:00:51.479 a local coffee shop situation, you know, to catch up 0:00:51.520 --> 0:00:55.440 on emails. How, how did that come to pass, and 0:00:55.560 --> 0:00:58.920 how does it actually work? Well. Decades before there was 0:00:58.960 --> 0:01:02.680 a WiFi standard, there was a Lohan net. Back in 0:01:02.720 --> 0:01:06.800 the late nineteen sixties, computer scientists and students at the 0:01:06.920 --> 0:01:09.600 University of Hawaii. We're trying to come up with a 0:01:09.600 --> 0:01:13.160 way that would let students on the various Hawaiian islands 0:01:13.480 --> 0:01:17.039 communicate with the main frame computer on the Oahu campus 0:01:17.080 --> 0:01:20.760 at the university. Their work was concurrent with the work 0:01:20.920 --> 0:01:23.880 of BBN, a company that was working on our bonnet 0:01:24.520 --> 0:01:27.319 and our ponette, you may remember, was the predecessor to 0:01:27.360 --> 0:01:30.199 the Internet. The purpose of our ponet was to find 0:01:30.200 --> 0:01:35.160 out ways to connect remote computers together, remote computers that 0:01:35.200 --> 0:01:37.800 were working on different computer architectures, and have a way 0:01:37.840 --> 0:01:41.640 that they can meaningfully communicate with each other. Well, this 0:01:41.760 --> 0:01:44.360 was happening around the same time. Now, one thing the 0:01:44.400 --> 0:01:46.520 group wanted to do was take advantage of a special 0:01:46.520 --> 0:01:50.760 way to send data between computers called packet switching. M 0:01:50.760 --> 0:01:54.640 I T had developed packet switching back in nineteen sixty five, 0:01:54.800 --> 0:01:58.720 so it was still a relatively new technology when the 0:01:58.760 --> 0:02:00.800 folks over at the University of Why You decided to 0:02:00.840 --> 0:02:04.400 try and create their own Aloha net. So what exactly 0:02:04.520 --> 0:02:07.680 is packet switching and why is it so important and 0:02:07.800 --> 0:02:11.320 how networks send information? Well, let's say you want to 0:02:11.360 --> 0:02:15.000 transfer a large file from one computer to another, a 0:02:15.080 --> 0:02:20.079 really big one. Let's say that it's maybe several gigabytes 0:02:20.120 --> 0:02:22.959 in size, which today is a pretty big file. Back 0:02:22.960 --> 0:02:25.240 in the days of nine that would have been an 0:02:25.280 --> 0:02:29.440 unimaginably huge file. But let's stick with it. Now. Let's 0:02:29.480 --> 0:02:32.160 say you're trying to send that file over a network. 0:02:32.680 --> 0:02:35.800 The bandwidth of that network might limit how large a 0:02:35.840 --> 0:02:40.040 file you'd be able to send. In other words, your connections, 0:02:40.120 --> 0:02:44.800 your routers, your switches, your buses, if they have a 0:02:44.919 --> 0:02:47.840 limit on how much information can pass through at one time, 0:02:48.560 --> 0:02:52.200 that might mean that you can't send that file. It's 0:02:52.240 --> 0:02:55.680 just too big to fit through the pipes. If you 0:02:55.760 --> 0:02:59.400 want to have kind of a poor analogy, but a 0:03:00.000 --> 0:03:03.160 physical analogy, imagine that you have a very narrow road 0:03:03.720 --> 0:03:07.280 and you're driving a really wide truck, and you're really 0:03:07.280 --> 0:03:10.480 wide truck is actually too wide for the narrow road. Well, 0:03:10.680 --> 0:03:12.200 looks like you're gonna have to find another way to 0:03:12.200 --> 0:03:14.280 get your truck to the other side of that road. 0:03:14.880 --> 0:03:17.400 That's kind of what I'm talking about here. So packet 0:03:17.440 --> 0:03:21.280 switching was a way to make this more manageable, to 0:03:22.200 --> 0:03:25.800 allow files to transfer across a network in a way 0:03:25.840 --> 0:03:31.840 that did not overly stress the infrastructure. Essentially, packet switching 0:03:31.840 --> 0:03:36.240 works by dividing files up into chunks of data called packets. 0:03:36.680 --> 0:03:38.440 You can think of them as like envelopes that have 0:03:38.640 --> 0:03:41.120 letters inside of them, and each letter is part of 0:03:41.120 --> 0:03:44.760 a file that you're sending across the Internet. Packets contain 0:03:44.800 --> 0:03:47.520 a little extra information in them in addition to the 0:03:47.560 --> 0:03:51.480 file itself. That information includes data about the computer that 0:03:51.760 --> 0:03:55.480 was sending the file the computer that's supposed to receive 0:03:55.560 --> 0:03:58.360 the file, so kind of like the return address and 0:03:58.400 --> 0:04:02.320 the send address, those two things would be included, and 0:04:02.360 --> 0:04:05.720 also how that particular chunk of data fits in with 0:04:05.880 --> 0:04:08.960 the rest of the information that's being sent. So you 0:04:08.960 --> 0:04:10.920 can also think of it as sort of like instructions 0:04:10.920 --> 0:04:13.440 on how to put a puzzle back together. So if 0:04:13.440 --> 0:04:16.880 I go with the mail analogy, as in like postal mail, 0:04:17.680 --> 0:04:20.240 every single piece of information is a piece of a puzzle, 0:04:20.800 --> 0:04:23.159 and with that piece of a puzzle, I include a 0:04:23.160 --> 0:04:25.440 little bit of instructions about where that piece fits. I 0:04:25.520 --> 0:04:28.600 might say this piece is the bottom right corner of 0:04:28.640 --> 0:04:32.279 the puzzle, and then the envelope has the address that 0:04:32.360 --> 0:04:34.840 I'm sending from and the address I'm sending to. Well, 0:04:34.880 --> 0:04:38.080 that's kind of like a packet of data. In packet switching, 0:04:38.120 --> 0:04:41.360 you send these smaller, more manageable chunks of data across 0:04:41.360 --> 0:04:44.440 a network. The chunks may or may not follow the 0:04:44.480 --> 0:04:47.200 same pathway to get to their destination. They may not 0:04:47.279 --> 0:04:50.440 all go through the exact same nodes across the Internet. 0:04:51.120 --> 0:04:53.720 The neat thing is they can all split up and 0:04:53.760 --> 0:04:58.040 take different pathways, and typically you have duplicate packets journeying 0:04:58.080 --> 0:05:01.520 to the destination to help ensure that the full file 0:05:01.760 --> 0:05:04.920 arrives where it needs to go. Otherwise the file will 0:05:04.920 --> 0:05:07.200 be corrupt because it will be missing a piece of 0:05:07.240 --> 0:05:09.520 the puzzle. Once the packets get to the right computer, 0:05:09.920 --> 0:05:13.760 they get reassembled into whatever the original file was, whether 0:05:13.800 --> 0:05:17.400 it's a text file, an image video, whatever it might be. 0:05:18.279 --> 0:05:20.720 The team at the University of Hawaii wanted to use 0:05:20.880 --> 0:05:26.120 packet switching technology coupled with radio transmissions in order to 0:05:26.240 --> 0:05:30.120 send information from the main frame and to receive information 0:05:30.200 --> 0:05:33.720 from students across the island chain. They decided to create 0:05:33.720 --> 0:05:37.719 a system that would transmit information using radio signals that 0:05:37.760 --> 0:05:42.520 were in the ultra high frequency or UHF range. UHF, 0:05:42.560 --> 0:05:46.840 apart from being a hilarious weird Al Yankovic movie, is 0:05:47.120 --> 0:05:51.680 a range of radio signals that fall into the spectrum 0:05:51.720 --> 0:05:54.200 that at the low end is at three hundred mega 0:05:54.240 --> 0:05:57.520 hurts and at the upper end is at three giga hurts. 0:05:57.800 --> 0:06:00.360 Now it hurts is a unit that refers to one 0:06:00.440 --> 0:06:03.920 cycle per second. I've talked about this recently, but it's 0:06:03.960 --> 0:06:06.880 always good to go over this again. Now imagine that 0:06:07.120 --> 0:06:11.640 a radio wave is a long sign wave with smooth, 0:06:11.880 --> 0:06:15.719 even peaks and valleys, and they just repeat over and 0:06:15.760 --> 0:06:17.320 over and over again. Now, if you were to take 0:06:17.360 --> 0:06:20.320 an arbitrary point, such as the peak of the wave, 0:06:20.839 --> 0:06:24.400 and measure it to the next peak over, you would 0:06:24.400 --> 0:06:29.000 have one wavelength of that radio wave. Radio waves travel 0:06:29.040 --> 0:06:31.840 at the speed of light, regardless of wavelength, if it's 0:06:31.839 --> 0:06:34.520 a short wavelength or a long wavelength. So if you 0:06:34.560 --> 0:06:37.839 know how long a wavelength is for a radio wave, 0:06:38.240 --> 0:06:40.880 you know how many radio waves will pass a given 0:06:40.920 --> 0:06:43.560 point in space every second, because you already know the 0:06:43.680 --> 0:06:46.840 speed at which they will travel. A three hundred mega 0:06:46.880 --> 0:06:50.839 Hurts radio wave will have three hundred million waves pass 0:06:50.960 --> 0:06:54.360 through a given point in space per second. A three 0:06:54.440 --> 0:06:59.080 giga Hurts radio wave will have three billion radio waves 0:06:59.120 --> 0:07:02.840 pass that same point per second. The three gig Hurts 0:07:02.880 --> 0:07:06.279 waves clearly have to be smaller than the mega Hurts 0:07:06.279 --> 0:07:08.400 ones because they're all traveling at the same speed. So 0:07:08.440 --> 0:07:11.280 the only way you can cram more wavelengths past the 0:07:11.360 --> 0:07:16.160 point per second is by decreasing the wavelength. The radio 0:07:16.200 --> 0:07:18.800 spectrum as a whole, by the way, starts all the 0:07:18.840 --> 0:07:23.560 way down at three hurts meaning only three extremely long 0:07:23.720 --> 0:07:27.120 radio waves would pass a given point in space every second, 0:07:27.600 --> 0:07:29.960 and it goes all the way up to three terra hurts, 0:07:30.000 --> 0:07:33.520 which is equivalent to three thousand giga hurts or three 0:07:33.680 --> 0:07:38.200 thousand billion cycles per second. So while UHF stands for 0:07:38.280 --> 0:07:42.240 ultra high frequency, it's nowhere near the top of the spectrum. 0:07:42.720 --> 0:07:47.320 Aloha net relied on to such frequencies in the UHF range. 0:07:47.400 --> 0:07:51.000 One frequency was used for outgoing signals from the main 0:07:51.000 --> 0:07:54.240 frame to the other computers, so the main computer would 0:07:54.240 --> 0:07:58.320 send signals out over one frequency to students, but the 0:07:58.360 --> 0:08:01.040 other frequency was used by the other computers to send 0:08:01.040 --> 0:08:04.000 messages back to the main frame, so the students machines 0:08:04.400 --> 0:08:07.000 would use a different frequency. So you had kind of 0:08:07.000 --> 0:08:09.320 two channels in a way. You had the outgoing and 0:08:09.360 --> 0:08:12.840 the incoming. But this created a possible problem. There could 0:08:12.960 --> 0:08:15.840 come an instance in which more than one computer was 0:08:15.880 --> 0:08:18.680 trying to communicate with the main frame at the same time, 0:08:19.080 --> 0:08:21.520 and when that happened, the signals were said to quote 0:08:21.560 --> 0:08:25.400 unquote collide with one another. It's sort of like trying 0:08:25.440 --> 0:08:28.360 to have multiple people talk over a single radio channel. 0:08:28.400 --> 0:08:30.840 Only one person can speak at a time. If multiple 0:08:30.880 --> 0:08:35.400 people try it's just a mess. So alohan Net adopted 0:08:35.400 --> 0:08:37.640 a strategy in which the main frame would send out 0:08:37.679 --> 0:08:41.560 a received signal whenever an incoming message came in without 0:08:41.559 --> 0:08:44.480 a collision. It was essentially saying, I am confirming that 0:08:44.559 --> 0:08:46.880 I got your message, and that would tell the sending 0:08:46.880 --> 0:08:49.560 computer that the message got through, and if the sending 0:08:49.600 --> 0:08:53.120 computer did not get such a response, it would attempt 0:08:53.160 --> 0:08:57.199 to send the packets of data again at a randomly 0:08:57.320 --> 0:09:02.000 determined time interval. That random interval was meant to decrease 0:09:02.080 --> 0:09:06.160 the possibility that another collision would occur because obviously more 0:09:06.200 --> 0:09:08.600 than one computer is involved in this, and if both 0:09:08.679 --> 0:09:12.280 computers tried to send the exact same data packets at 0:09:12.360 --> 0:09:15.040 the same time intervals over and over again, you're just 0:09:15.040 --> 0:09:18.720 gonna keep getting collisions. This time, there would be the 0:09:18.760 --> 0:09:20.720 hope that there would be no collisions because you would 0:09:20.760 --> 0:09:24.520 have this somewhat random time interval that is spacing things 0:09:24.559 --> 0:09:27.920 out a little bit. Now. In its original configuration, alohan 0:09:28.040 --> 0:09:31.160 that was not terribly efficient. It had a throughput rate 0:09:31.280 --> 0:09:35.439 of just eighteen percent and most of the bandwidth went unused, 0:09:35.760 --> 0:09:38.720 and so the team needed to come up with a fix. First, 0:09:39.000 --> 0:09:42.160 they tried the old time sharing route. Time sharing is 0:09:42.200 --> 0:09:45.840 when you have several terminals connected to a centralized computer. 0:09:46.360 --> 0:09:49.280 The computer can only work on one set of instructions 0:09:49.320 --> 0:09:52.000 at a time, and so users have to wait a 0:09:52.120 --> 0:09:56.040 turn to access the computers processing power and memory and etcetera. 0:09:56.240 --> 0:09:59.960 But computers work really fast and so frequently it would 0:10:00.000 --> 0:10:02.600 feel like you were working on a mainframe in real 0:10:02.679 --> 0:10:05.600 time at the same time as everybody else, though in 0:10:05.640 --> 0:10:08.120 fact the computer is actually rushing to complete one set 0:10:08.120 --> 0:10:11.280 of instructions before starting on the next one. The problem 0:10:11.320 --> 0:10:14.439 with time sharing over radio network was that the computers 0:10:14.480 --> 0:10:17.800 had to follow a schedule of when they could send packets, 0:10:18.320 --> 0:10:20.319 so if it wasn't their time to send a packet, 0:10:20.360 --> 0:10:22.320 they had to wait and so and meant that there 0:10:22.320 --> 0:10:25.360 were wasted cycles since sometimes the computer had nothing to 0:10:25.440 --> 0:10:29.800 send and so those scheduled transmission times would go unused. However, 0:10:29.920 --> 0:10:32.880 this did increase the throughput rate for a Looha net, 0:10:32.920 --> 0:10:36.400 so it improved things a little bit. The team decided 0:10:36.520 --> 0:10:39.400 to try a different approach to improve the system further, 0:10:39.760 --> 0:10:43.360 and they designed instructions so that client machines, the ones 0:10:43.480 --> 0:10:47.040 that are sending request to the centralized computer, would monitor 0:10:47.120 --> 0:10:50.080 the traffic on the radio channel to determine when the 0:10:50.160 --> 0:10:53.040 channel was free. So essentially they're listening for the quiet spots, 0:10:53.480 --> 0:10:56.320 and then the client machine would send packets over that 0:10:56.480 --> 0:10:59.760 radio channel. The packets were actually smaller at this point, 0:11:00.080 --> 0:11:03.360 which would allow for more gaps between packets, and that 0:11:03.400 --> 0:11:06.600 would allow other computers to slip other packets in. So 0:11:06.640 --> 0:11:11.200 while the messages appear to be consistent and continuous, in 0:11:11.280 --> 0:11:13.880 fact it's a bunch of tiny little puzzle pieces, and 0:11:13.920 --> 0:11:16.920 occasionally there's enough of a gap for other puzzle pieces 0:11:16.960 --> 0:11:19.600 to sneak in, and the centralized computer would just sort 0:11:19.679 --> 0:11:23.240 everything based upon the meta information on the packets. This 0:11:23.280 --> 0:11:27.800 approach got the name Carrier Sense Multiple Access or c 0:11:28.280 --> 0:11:32.120 s m A. The system continued to monitor collisions as well, 0:11:32.559 --> 0:11:36.720 so it's full name was c s m A DASH 0:11:36.960 --> 0:11:41.440 c D or Carrier Since Multiple Access with Collision Detection. 0:11:42.400 --> 0:11:46.199 Now I've got more to say about the evolution toward WiFi, 0:11:46.240 --> 0:11:48.960 but before I go further, let's take a quick break 0:11:49.080 --> 0:11:59.800 to thank our sponsor Aloha. Nette was up and running 0:12:00.040 --> 0:12:02.640 by nineteen seventy one, but it would still be more 0:12:02.640 --> 0:12:06.120 than twenty years before we'd see the first WiFi standard 0:12:06.360 --> 0:12:09.320 get unveiled. He could be fourteen years before I have 0:12:09.360 --> 0:12:12.680 another big moment to talk about in the evolution toward WiFi. 0:12:13.320 --> 0:12:17.559 That moment happened in nineteen five when the United States 0:12:17.640 --> 0:12:21.840 Federal Communications Commission, or FCC changed the rules about the 0:12:21.920 --> 0:12:27.000 radio spectrum. Every country has rules about which frequency bands 0:12:27.080 --> 0:12:30.600 in the radio spectrum may be used for specific applications. 0:12:30.880 --> 0:12:34.120 For example, in the United States, AM radio has all 0:12:34.200 --> 0:12:38.080 frequencies between five thirty five killer hurts and one thousand, 0:12:38.200 --> 0:12:42.640 six hundred five killer hurts. No other technology is allowed 0:12:42.679 --> 0:12:47.000 to use those radio frequencies. This prevents various technologies from 0:12:47.040 --> 0:12:50.600 interfering with one another. If you didn't have restrictions on 0:12:50.679 --> 0:12:54.640 who could use which frequency, then whatever frequency was the 0:12:54.720 --> 0:12:58.800 strongest had the greatest UH energy behind it in any 0:12:58.800 --> 0:13:01.840 given area would win out and it would be chaos. 0:13:02.400 --> 0:13:05.520 And so the United States divvied up the radio spectrum 0:13:05.520 --> 0:13:09.760 for specific uses, which included not only communications technology but 0:13:09.840 --> 0:13:13.959 also stuff like microwave ovens. Say what, and by the way, 0:13:14.000 --> 0:13:17.120 this is not just the US. Other countries also have 0:13:17.240 --> 0:13:20.679 done this, But it's because technology like microwave ovens can 0:13:20.800 --> 0:13:25.280 generate radio frequencies of their own, not to communicate, but 0:13:25.520 --> 0:13:28.520 that can be a byproduct of their operations. So the 0:13:28.600 --> 0:13:33.800 United States FCC mandated that manufacturers of microwaves and other 0:13:34.120 --> 0:13:38.160 technologies that create these radio waves make sure their products 0:13:38.200 --> 0:13:42.080 only generated radio frequencies within specific bands in order to 0:13:42.120 --> 0:13:45.520 avoid creating interference for other technology. So it's not like 0:13:45.559 --> 0:13:48.959 the US specifically said, hey, let's set aside the slice 0:13:48.960 --> 0:13:52.000 of radio frequency spectrum so that microwaves can talk to 0:13:52.040 --> 0:13:54.920 one another. In staid, they said, hey, let's make sure 0:13:54.920 --> 0:13:59.520 all microwave oven manufacturers be certain that their ovens only 0:13:59.559 --> 0:14:02.880 generate radio frequencies in this slice so that the ovens 0:14:02.920 --> 0:14:06.240 don't interfere with communications equipment. In other words, they set 0:14:06.280 --> 0:14:08.760 aside a certain slice of the radio spectrum and said 0:14:09.120 --> 0:14:11.679 this is your playground. You can create stuff that creates 0:14:11.760 --> 0:14:14.800 radio frequencies in this range, and that shouldn't mess up 0:14:14.880 --> 0:14:19.440 anything that's on either side of that frequency range. These bands, 0:14:19.560 --> 0:14:22.760 the ones set aside for equipment that can generate radio 0:14:22.800 --> 0:14:27.120 waves but aren't necessarily communication tech, are called I S 0:14:27.320 --> 0:14:31.120 M bands. The I s M stands for Industrial, Scientific, 0:14:31.200 --> 0:14:36.080 and Medical. These bands cover several different separate groups of frequencies, 0:14:36.160 --> 0:14:38.960 but two of them include the two point four giga 0:14:39.000 --> 0:14:41.640 Hurts to two point five gig Hurts band and the 0:14:41.760 --> 0:14:44.920 five point seven to five gig Hurts to five point 0:14:45.000 --> 0:14:48.280 eight seven five giga Hurts bands. These are going to 0:14:48.320 --> 0:14:51.480 be very important for our discussions on WiFi. Now again 0:14:51.560 --> 0:14:55.280 we look at five, when the FCC decided it would 0:14:55.320 --> 0:14:59.040 open up three I s M bands to unlicensed use 0:14:59.480 --> 0:15:01.600 that would in flude the two point four giga Hurts 0:15:01.600 --> 0:15:04.160 and the five point seven to five gig Hurts bands. 0:15:04.760 --> 0:15:08.720 Unlicensed use required a couple of technological allowances. One was 0:15:08.760 --> 0:15:11.120 that the transmitters would have to be very low power 0:15:11.240 --> 0:15:14.640 in the one watt range. Another was that gadgets making 0:15:14.760 --> 0:15:17.640 use of that frequency would need a high tolerance to 0:15:17.680 --> 0:15:20.440 interference since other devices were still going to be giving 0:15:20.440 --> 0:15:23.840 off radio waves at those frequencies. Essentially, what the FCC 0:15:24.040 --> 0:15:27.160 was saying is, you can develop technologies that can work 0:15:27.160 --> 0:15:29.920 on these ranges as long as they aren't so powerful 0:15:29.960 --> 0:15:32.960 that they're going to interfere with other technologies, and you 0:15:33.000 --> 0:15:35.560 do it with the understanding that there's already stuff out 0:15:35.560 --> 0:15:38.520 there that's generating radio waves in these frequencies. So whatever 0:15:38.560 --> 0:15:41.240 you create needs to be done in such a way 0:15:41.280 --> 0:15:44.960 that it can tolerate that This decision in set the 0:15:44.960 --> 0:15:49.160 foundation for WiFi, which still would not debut for another decade, 0:15:49.200 --> 0:15:51.800 but that didn't mean there weren't people working on the 0:15:51.840 --> 0:15:55.200 idea in the meantime. One of those people was Vic Hayes. 0:15:55.640 --> 0:15:59.840 Hayes had joined the NCR Corporation in the nineteen seventies. 0:16:00.240 --> 0:16:04.560 In CR, which originally stood for National Cash Register, had 0:16:04.600 --> 0:16:08.160 been involved in various technologies since its founding in the 0:16:08.240 --> 0:16:12.080 late nineteenth century. In CR's goal was to create a 0:16:12.160 --> 0:16:15.560 standard that the company could then use in its own systems. 0:16:15.880 --> 0:16:18.200 The idea was that the standard would allow companies to 0:16:18.240 --> 0:16:22.440 create systems that connected devices like front end retail equipment 0:16:22.520 --> 0:16:27.040 such as cash registers and back end mainframe systems and 0:16:27.160 --> 0:16:31.600 using radio waves instead of cables or other clunky methodologies. 0:16:32.000 --> 0:16:34.080 And they didn't want to go a proprietary route. They 0:16:34.080 --> 0:16:36.320 wanted to create a standard that would work so that 0:16:37.200 --> 0:16:42.240 various O E M companies could create products that used it. 0:16:42.560 --> 0:16:45.320 Hayes had done some work and authoring standards for data 0:16:45.360 --> 0:16:49.440 communications as part of his job previously, and NCR was 0:16:49.520 --> 0:16:52.880 interested in finding an unlicensed use for the two point 0:16:52.920 --> 0:16:55.760 for giga hurts I s M band, n c R 0:16:55.840 --> 0:16:58.600 and a T and T had developed a working predecessor 0:16:58.800 --> 0:17:03.760 to the would essentially evolve into WiFi in nine, and 0:17:03.840 --> 0:17:07.359 that was called wave land. They submitted the design of 0:17:07.400 --> 0:17:11.080 this wireless protocol to the I E E E A 0:17:11.240 --> 0:17:16.280 O two LAND slash MAN Standards Committee. Land, by the way, 0:17:16.320 --> 0:17:20.040 stands for local Area network and MAN for a Municipality 0:17:20.119 --> 0:17:23.679 Area network or Municipal Area network. This led to the 0:17:23.720 --> 0:17:26.840 need to form a new working group within that committee, 0:17:27.000 --> 0:17:29.760 The eight O two Committee to Create a Standard for 0:17:29.840 --> 0:17:34.480 Wireless Networking Communication NCR chose Hayes to head up a 0:17:34.520 --> 0:17:38.159 working group to that effect in nine. The working groups 0:17:38.200 --> 0:17:42.200 designation was a O two point eleven and their goal 0:17:42.280 --> 0:17:46.240 was to create a standard for wireless local area networks. Now, 0:17:46.240 --> 0:17:49.159 a local area network is pretty self explanatory. It's a 0:17:49.200 --> 0:17:52.399 network of computing devices that are locally connected to one another, 0:17:52.920 --> 0:17:56.840 generally contained within a building or maybe a campus of buildings. 0:17:57.240 --> 0:18:01.200 The devices can intercommunicate with one another. A LAND can 0:18:01.280 --> 0:18:05.040 be but doesn't have to be connected to wider networks 0:18:05.080 --> 0:18:07.640 like the Internet, and in the old days, the only 0:18:07.680 --> 0:18:11.280 way you could set up a LAND was to actually 0:18:11.280 --> 0:18:14.080 have physical connections between all the different machines and some 0:18:14.160 --> 0:18:17.480 sort of hub, but NCR wanted to do away with 0:18:17.560 --> 0:18:21.280 those physical connectors and create a standard that manufacturers could 0:18:21.359 --> 0:18:25.960 use to build in wireless communication capabilities directly into their products. 0:18:26.680 --> 0:18:30.840 Hayes had some radio communications background and had previous experience 0:18:30.880 --> 0:18:34.600 helping create communication standards, but still wasn't sure he was 0:18:34.640 --> 0:18:37.000 the right man for the job. As it turned out, 0:18:37.040 --> 0:18:40.439 he absolutely was. He gathered a group of experts together 0:18:40.800 --> 0:18:43.520 and they began to debate what needed to go into 0:18:43.520 --> 0:18:47.040 the standard, and the first big argument was over two 0:18:47.080 --> 0:18:53.199 different modulation strategies, frequency hopping or direct sequence. Both of 0:18:53.200 --> 0:18:56.439 those techniques are meant to use a larger bandwidth for 0:18:56.480 --> 0:19:01.000 transmission than what would otherwise be necessary for the specific 0:19:01.160 --> 0:19:05.119 type of data you're sending back and forth. Frequency hopping 0:19:05.200 --> 0:19:09.359 spread spectrum or f h s S divides a large 0:19:09.440 --> 0:19:13.840 bandwidth into parallel, narrow channels there are large enough to 0:19:13.920 --> 0:19:15.919 hold the data in question. If we go back to 0:19:15.960 --> 0:19:19.160 talking about vehicles and roads, this would be saying, let's 0:19:19.200 --> 0:19:22.080 imagine that you have a really, really wide highway I'm 0:19:22.119 --> 0:19:26.240 talking twenty lanes wide. Uh, and at first you don't 0:19:26.240 --> 0:19:31.120 have any lanes painted in there, it's just an enormous road. Well, 0:19:31.280 --> 0:19:34.679 you could try and use it that way. But frequency 0:19:34.680 --> 0:19:38.080 hopping would allow you to create narrower lanes, lanes that 0:19:38.119 --> 0:19:40.400 are wide enough for a vehicle, so that you could 0:19:40.440 --> 0:19:43.639 have twenty vehicles traveling on there if they all were 0:19:43.680 --> 0:19:46.160 sticking to their own lanes. That's kind of the idea 0:19:46.240 --> 0:19:49.639 behind frequency hopping. The system sends data in a semi 0:19:49.760 --> 0:19:53.320 random way to one of those channels, but that means 0:19:53.400 --> 0:19:56.840 the other channels go unused in the process, and because 0:19:56.960 --> 0:19:59.880 only one channel is in use at any given time, 0:20:00.320 --> 0:20:03.720 you're technically wasting bandwidth equal to the size of the 0:20:03.840 --> 0:20:07.480 channel multiplied by the number of channels minus one channel, 0:20:07.480 --> 0:20:10.560 because you're already using one. So this would be like saying, yeah, 0:20:10.600 --> 0:20:13.800 you have a highway, it's twenty lanes wide. You've painted 0:20:13.800 --> 0:20:17.040 these lanes in there, so you can randomly choose a 0:20:17.160 --> 0:20:20.119 lane between one and twenty and you're fine, But that 0:20:20.160 --> 0:20:22.600 means the other nineteen lanes are going unused. It's not 0:20:22.760 --> 0:20:25.840 an efficient use of space. That was the argument against 0:20:26.119 --> 0:20:30.520 this strategy. Uh, that's obviously inefficient, but it was also 0:20:30.640 --> 0:20:34.199 technically easier to do, and so about half the working 0:20:34.200 --> 0:20:37.760 group wanted to pursue frequency hopping as the modulation methodology 0:20:37.760 --> 0:20:41.199 of choice because while it wasn't efficient, it was easier 0:20:41.240 --> 0:20:46.640 to implement. Direct sequence spread spectrum or d S S 0:20:46.640 --> 0:20:51.240 S introduces pseudo random noise into the signal it sins 0:20:51.520 --> 0:20:54.520 in order to change the phase of the signal itself. 0:20:54.560 --> 0:20:58.000 This creates the digital equivalent of static. It would seem 0:20:58.040 --> 0:21:01.400 to be meaningless information when you received it, but if 0:21:01.440 --> 0:21:05.200 you knew which pseudo random sequence was used to create 0:21:05.280 --> 0:21:08.639 the phase shift, you could reverse that whole process. You 0:21:08.680 --> 0:21:13.040 could d spread the static and extract the meaningful information 0:21:13.080 --> 0:21:16.400 out of it. D S S S is more challenging 0:21:16.440 --> 0:21:19.600 to implement than f H S S, but it also 0:21:19.800 --> 0:21:22.000 is more robust, and so the other half of the 0:21:22.040 --> 0:21:25.560 group wanted to follow that idea. Both of those methodologies 0:21:25.560 --> 0:21:28.600 would allow for multiple devices to communicate across a band 0:21:28.640 --> 0:21:32.320 of frequencies without interfering with one another, and the I 0:21:32.560 --> 0:21:35.760 E E E Rules stated that in order to adopt 0:21:35.800 --> 0:21:38.920 a strategy, you had to secure the support of at 0:21:39.000 --> 0:21:42.679 least seventy of the working group, but each method had 0:21:42.720 --> 0:21:46.680 about of the support. The only solution was to create 0:21:46.720 --> 0:21:49.960 a system that could support both modulation strategies, and so 0:21:50.080 --> 0:21:53.640 that's what the group decided to do. I'll wrap up 0:21:53.680 --> 0:21:55.879 the history of WiFi and give all a low down 0:21:55.920 --> 0:21:58.439 on what the different variations mean in just a second. 0:21:58.440 --> 0:22:01.320 But first let's take another their quick break to thank 0:22:01.359 --> 0:22:11.720 our sponsor. While the working group began to hash out 0:22:11.760 --> 0:22:15.440 the standards that would become fundamental to WiFi, a group 0:22:15.520 --> 0:22:20.399 of engineers, astronauts and astronomers were developing a technique that 0:22:20.480 --> 0:22:24.440 would become just as important. Vick Hayes, whom I mentioned earlier, 0:22:24.600 --> 0:22:28.160 is sometimes called the father of WiFi, but another man, 0:22:28.600 --> 0:22:33.840 John O'Sullivan, also gets that title on occasion. O'Sullivan is 0:22:33.880 --> 0:22:38.080 an electrical engineer, and he focused on radio astronomy. He 0:22:38.160 --> 0:22:41.119 led a team that developed a way to reduce multi 0:22:41.240 --> 0:22:46.080 path interference of radio signals, something that was absolutely necessary 0:22:46.160 --> 0:22:48.639 if you want to have a smooth experience with a 0:22:48.720 --> 0:22:52.960 wireless local area network. His team's work would receive a 0:22:53.040 --> 0:22:58.360 patent credited to the Commonwealth Scientific and Industrial Research Organization 0:22:58.920 --> 0:23:02.480 or c s i r O, which is an Australian 0:23:02.560 --> 0:23:05.760 federal government agency. The really funny thing to me is 0:23:05.800 --> 0:23:08.639 that this research was originally part of an experiment to 0:23:08.720 --> 0:23:13.360 try and detect expanding many black holes. That experiment failed, 0:23:13.560 --> 0:23:16.680 but the technique would end up changing the world once 0:23:16.720 --> 0:23:21.159 incorporated into WiFi. Meanwhile, back in the eight O two 0:23:21.160 --> 0:23:25.080 point eleven Working Group, the standard was getting closer to 0:23:25.160 --> 0:23:28.320 becoming a real thing. The very first version of the 0:23:28.359 --> 0:23:34.119 protocol was unveiled in It had a maximum download speed 0:23:34.200 --> 0:23:38.600 of two megabits per second, which is excruciating lee slow 0:23:38.720 --> 0:23:41.920 these days, and that was only if you could use 0:23:42.000 --> 0:23:45.880 the D S S S approach. Remember, it involved both 0:23:45.880 --> 0:23:49.760 the direct spread and the frequency hopping. If you used 0:23:49.840 --> 0:23:53.600 frequency hopping, you topped out at one megabit per second. 0:23:54.280 --> 0:23:56.920 That didn't exactly cause everyone to throw their cables out 0:23:56.920 --> 0:23:59.760 their respective windows in a fit of joy, but it 0:23:59.840 --> 0:24:05.200 was progress. In ninet, the Working Group released a new protocol, 0:24:05.760 --> 0:24:09.760