1 00:00:00,000 --> 00:00:00,990 In this lesson, 2 00:00:00,990 --> 00:00:03,270 we're going to cover cellular connections. 3 00:00:03,270 --> 00:00:05,820 Now, most of us have a smartphone in our pocket these days, 4 00:00:05,820 --> 00:00:07,800 and we use cellular almost every day to connect 5 00:00:07,800 --> 00:00:10,560 to the wide area network known as the internet. 6 00:00:10,560 --> 00:00:12,120 Now, when we talk about cellular, 7 00:00:12,120 --> 00:00:14,070 this includes not just our smartphones, 8 00:00:14,070 --> 00:00:15,270 but also our tablets, 9 00:00:15,270 --> 00:00:17,580 dedicated cellular modems for corporate networks, 10 00:00:17,580 --> 00:00:20,550 or cellular wireless access points known as hotspots 11 00:00:20,550 --> 00:00:22,980 or even fixed cellular service that we can get in our homes 12 00:00:22,980 --> 00:00:24,660 and offices these days. 13 00:00:24,660 --> 00:00:27,420 Now, there is a wide range of cellular technologies in use, 14 00:00:27,420 --> 00:00:31,560 including older ones like 2G, 3G, 4G, LTE, 15 00:00:31,560 --> 00:00:34,200 and the most modern version, 5G. 16 00:00:34,200 --> 00:00:36,090 Whenever you hear somebody talking about the G, 17 00:00:36,090 --> 00:00:39,090 like 4G or 5G, all we're basically talking about 18 00:00:39,090 --> 00:00:41,820 is which generation of cellular technology is being used 19 00:00:41,820 --> 00:00:45,180 by the cellular modem in that smartphone or other device. 20 00:00:45,180 --> 00:00:47,340 Basically, for any of these devices to connect 21 00:00:47,340 --> 00:00:48,540 to the cellular network, 22 00:00:48,540 --> 00:00:50,430 they are going to have an embedded cellular modem 23 00:00:50,430 --> 00:00:52,467 that supports one or more of these technologies 24 00:00:52,467 --> 00:00:54,900 and the associated frequencies for them. 25 00:00:54,900 --> 00:00:56,340 Now the first cellular networks, 26 00:00:56,340 --> 00:00:58,140 which are now referred to as 1G, 27 00:00:58,140 --> 00:01:01,050 were developed all the way back in the 1980s. 28 00:01:01,050 --> 00:01:03,390 These 1G phones communicate using a frequency 29 00:01:03,390 --> 00:01:05,640 of 30 kilohertz, and they had a bandwidth of about 30 00:01:05,640 --> 00:01:07,320 two kilobits per second, 31 00:01:07,320 --> 00:01:08,550 so they really weren't pushing a lot 32 00:01:08,550 --> 00:01:10,530 of data over these 1G handsets, 33 00:01:10,530 --> 00:01:12,330 and instead they were simply dedicated 34 00:01:12,330 --> 00:01:14,820 to providing voice calls for the most part. 35 00:01:14,820 --> 00:01:16,110 As time went on though, 36 00:01:16,110 --> 00:01:18,060 cell phones moved into their second generation, 37 00:01:18,060 --> 00:01:21,120 known as 2G during the late 1990s. 38 00:01:21,120 --> 00:01:24,150 2G devices communicated over a GSM network 39 00:01:24,150 --> 00:01:26,970 using the 1800 megahertz frequency band. 40 00:01:26,970 --> 00:01:29,280 The big difference here is that 2G devices 41 00:01:29,280 --> 00:01:32,010 ran over a digital network that used multiplexing, 42 00:01:32,010 --> 00:01:33,420 and so it could start to use data 43 00:01:33,420 --> 00:01:35,850 in addition to just providing phone calls. 44 00:01:35,850 --> 00:01:38,070 Now the data was not super fast though. 45 00:01:38,070 --> 00:01:40,170 Here in 2G we were talking about speed 46 00:01:40,170 --> 00:01:41,670 similar to a dial up modem, 47 00:01:41,670 --> 00:01:45,000 which was usually in the range of 14.4 kilobits per second 48 00:01:45,000 --> 00:01:48,530 to 64 kilobits per second using the GPRS 49 00:01:48,530 --> 00:01:51,180 or the general packet radio service. 50 00:01:51,180 --> 00:01:54,750 In fact, when I started my first company back in 1999, 51 00:01:54,750 --> 00:01:56,910 I had a 2G flip phone that I used 52 00:01:56,910 --> 00:01:59,010 and I was able to tether it to my laptop 53 00:01:59,010 --> 00:02:00,630 and use it to access the internet 54 00:02:00,630 --> 00:02:03,180 and email invoices to my clients using this low speed 55 00:02:03,180 --> 00:02:05,370 connection after I serviced their property 56 00:02:05,370 --> 00:02:07,200 and I was back in my car. 57 00:02:07,200 --> 00:02:10,139 Now, 2G gave us a lot of benefits with cellular devices, 58 00:02:10,139 --> 00:02:12,390 even though those speeds were quite limited. 59 00:02:12,390 --> 00:02:14,820 2G devices were the first ones to have SMS 60 00:02:14,820 --> 00:02:16,710 and text messaging, as well as the ability 61 00:02:16,710 --> 00:02:19,020 to use international roaming, conference calls 62 00:02:19,020 --> 00:02:21,960 and the use of internet while away from our computers. 63 00:02:21,960 --> 00:02:25,170 Another evolution in 2G was the introduction of the edge, 64 00:02:25,170 --> 00:02:28,080 or enhanced data rates for GSM evolution, 65 00:02:28,080 --> 00:02:30,750 which brought speeds up to one megabits per second 66 00:02:30,750 --> 00:02:33,630 to most modern 2G devices, like the first iPhone 67 00:02:33,630 --> 00:02:36,210 when it was released back in 2008. 68 00:02:36,210 --> 00:02:39,240 Now the third generation of cellular saw the release of 3G 69 00:02:39,240 --> 00:02:41,010 with faster data speeds. 70 00:02:41,010 --> 00:02:45,000 At a minimum, 3G networks must support at least 144 kilobits 71 00:02:45,000 --> 00:02:47,760 per second to be known as a 3G network, 72 00:02:47,760 --> 00:02:49,860 but most devices were faster than that 73 00:02:49,860 --> 00:02:53,010 and they supported speeds of around 384 kilobits per second 74 00:02:53,010 --> 00:02:56,280 while moving in a car, or up to two megabits per second 75 00:02:56,280 --> 00:02:58,650 if you are walking or standing still. 76 00:02:58,650 --> 00:03:01,710 To provide these faster data speeds, 3G devices used 77 00:03:01,710 --> 00:03:05,250 a wider frequency band with frequencies from 1.6 gigahertz 78 00:03:05,250 --> 00:03:08,040 to two gigahertz being used within that 3G standard 79 00:03:08,040 --> 00:03:10,170 depending on where you lived in the world. 80 00:03:10,170 --> 00:03:11,700 Now there are three different technologies 81 00:03:11,700 --> 00:03:13,830 that were actually used with 3G networks. 82 00:03:13,830 --> 00:03:18,420 These are WCDMA, HSPA and HSPA+. 83 00:03:18,420 --> 00:03:22,200 WCDMA is the wideband code division multiple access 84 00:03:22,200 --> 00:03:24,270 that's used by the UMTS standard 85 00:03:24,270 --> 00:03:25,830 and can reach data speeds of up to about 86 00:03:25,830 --> 00:03:27,510 two megabits per second. 87 00:03:27,510 --> 00:03:30,810 This is actually the slowest of all of the 3G technologies. 88 00:03:30,810 --> 00:03:34,290 Now an improvement to WCDMA was called HSPA 89 00:03:34,290 --> 00:03:36,570 or the high speed packet access standard, 90 00:03:36,570 --> 00:03:40,230 and it could reach speeds up to 14.4 megabits per second. 91 00:03:40,230 --> 00:03:43,920 This is sometimes referred to as 3.5G by the industry. 92 00:03:43,920 --> 00:03:46,440 Over time high speed packet access evolution 93 00:03:46,440 --> 00:03:49,740 or HSPA plus was released and this brought speeds up to 94 00:03:49,740 --> 00:03:51,600 around 50 megabits per second, 95 00:03:51,600 --> 00:03:56,600 and you'll sometimes hear HSPA+ referred to as 3.75G. 96 00:03:56,610 --> 00:03:59,430 Now, the fourth generation of cellular saw the release of 4G 97 00:03:59,430 --> 00:04:01,560 with even faster speeds and the introduction 98 00:04:01,560 --> 00:04:05,400 of multiple input, multiple output, or MIMO, radio sets. 99 00:04:05,400 --> 00:04:08,250 With 4G, we could get speeds of up to 100 megabits 100 00:04:08,250 --> 00:04:09,990 per second while driving in a car 101 00:04:09,990 --> 00:04:11,670 and up to one gigabit per second 102 00:04:11,670 --> 00:04:13,500 for fixed stationary cellular modems 103 00:04:13,500 --> 00:04:15,210 like you would use in your house. 104 00:04:15,210 --> 00:04:18,240 4G devices even had a wider frequency band, 105 00:04:18,240 --> 00:04:20,640 covering frequencies from two to eight gigahertz 106 00:04:20,640 --> 00:04:23,550 depending on the implementation in your given country. 107 00:04:23,550 --> 00:04:27,600 Now, when 4G first came out, it was often called 4G LTE, 108 00:04:27,600 --> 00:04:30,330 Or 4G long term evolution. 109 00:04:30,330 --> 00:04:33,150 These devices could actually reach beads of up to 100 110 00:04:33,150 --> 00:04:34,680 megabits per second. 111 00:04:34,680 --> 00:04:37,200 Over time, there was an improved version of LTE 112 00:04:37,200 --> 00:04:40,140 called LTE Advanced or LTEA, 113 00:04:40,140 --> 00:04:42,120 and this was an advanced version of LTE 114 00:04:42,120 --> 00:04:43,350 that added more capabilities 115 00:04:43,350 --> 00:04:45,540 and increased speeds of two to three times 116 00:04:45,540 --> 00:04:48,570 that of a normal LTE, and under perfect conditions 117 00:04:48,570 --> 00:04:50,580 when you're using a stationary cellular modem, 118 00:04:50,580 --> 00:04:53,760 you could reach speeds of up to one gigabit per second. 119 00:04:53,760 --> 00:04:55,470 Now, the fifth generation of cellular 120 00:04:55,470 --> 00:04:57,240 is what we saw the release of 5G, 121 00:04:57,240 --> 00:05:00,180 with faster speed and much more capability. 122 00:05:00,180 --> 00:05:03,120 5G is actually pretty new, and its worldwide deployment 123 00:05:03,120 --> 00:05:05,610 only began back in 2019. 124 00:05:05,610 --> 00:05:08,610 5G devices bring an enormous improvement over the previous 125 00:05:08,610 --> 00:05:10,260 generation's devices too. 126 00:05:10,260 --> 00:05:13,620 With 5G, we can get speeds of up to 10 gigabits per second 127 00:05:13,620 --> 00:05:15,990 using high-band 5G frequencies, 128 00:05:15,990 --> 00:05:17,550 and this is one of the biggest differences 129 00:05:17,550 --> 00:05:20,070 with 5G over the older generations. 130 00:05:20,070 --> 00:05:22,110 5G is actually split up into three 131 00:05:22,110 --> 00:05:23,700 different frequencies bands. 132 00:05:23,700 --> 00:05:25,650 We have the low band, the mid band, 133 00:05:25,650 --> 00:05:27,600 and the high-band frequencies. 134 00:05:27,600 --> 00:05:30,106 Now the low band frequencies are between 600 135 00:05:30,106 --> 00:05:31,680 and 850 megahertz 136 00:05:31,680 --> 00:05:33,750 and they provide with speeds of only 30 137 00:05:33,750 --> 00:05:36,120 to 250 megabits per second. 138 00:05:36,120 --> 00:05:38,760 The benefits of using this low band frequency range though 139 00:05:38,760 --> 00:05:40,170 is that it has a very long range 140 00:05:40,170 --> 00:05:42,030 and can cover an area similar in size 141 00:05:42,030 --> 00:05:44,400 to the older 4G networks. 142 00:05:44,400 --> 00:05:47,370 The mid band frequency band operates between 2.5 143 00:05:47,370 --> 00:05:50,400 to 3.7 gigahertz, and this higher frequency band 144 00:05:50,400 --> 00:05:53,550 does support higher data rates of 100 to 900 megabits 145 00:05:53,550 --> 00:05:57,000 per second, but each cell tower does cover less area 146 00:05:57,000 --> 00:05:59,940 than that low band or a 4G tower could. 147 00:05:59,940 --> 00:06:03,180 As of 2021, most 5G deployments were being done 148 00:06:03,180 --> 00:06:05,400 using mid-frequency towers because it provides 149 00:06:05,400 --> 00:06:08,520 a good balance of coverage with those higher speeds. 150 00:06:08,520 --> 00:06:11,370 Now, the high-band frequencies operate between 25 151 00:06:11,370 --> 00:06:13,050 to 39 gigahertz, 152 00:06:13,050 --> 00:06:15,870 and this much higher frequency band does support extremely 153 00:06:15,870 --> 00:06:18,690 fast speeds in the gigabit per second range. 154 00:06:18,690 --> 00:06:20,940 The big challenge here though is that these frequencies 155 00:06:20,940 --> 00:06:23,130 operate in millimeter wave bands 156 00:06:23,130 --> 00:06:24,630 and this causes the range of those towers 157 00:06:24,630 --> 00:06:26,640 to be much, much smaller. 158 00:06:26,640 --> 00:06:28,770 Because of this smaller millimeter waveband, 159 00:06:28,770 --> 00:06:30,930 the signal is also easily blocked by walls, 160 00:06:30,930 --> 00:06:32,790 windows, and other objects. 161 00:06:32,790 --> 00:06:35,430 For this reason, there's not a lot of high-band deployments 162 00:06:35,430 --> 00:06:36,510 going on yet. 163 00:06:36,510 --> 00:06:38,230 So far we're seeing these deployed near areas 164 00:06:38,230 --> 00:06:40,200 where a lot of people are expected to crowd 165 00:06:40,200 --> 00:06:42,870 into a small area such as near a sports stadium, 166 00:06:42,870 --> 00:06:44,910 a amusement park or a convention center, 167 00:06:44,910 --> 00:06:46,860 but otherwise, most people are still using 168 00:06:46,860 --> 00:06:48,720 those mid-frequency bands. 169 00:06:48,720 --> 00:06:50,940 Alright, I know I just covered a ton of facts 170 00:06:50,940 --> 00:06:52,680 and figures for you when we talked about these different 171 00:06:52,680 --> 00:06:54,360 generations of cellular technology, 172 00:06:54,360 --> 00:06:56,947 and you are probably freaking out right now wondering, 173 00:06:56,947 --> 00:06:58,950 "Do I have to memorize all these speeds 174 00:06:58,950 --> 00:07:00,600 and frequencies for each one?" 175 00:07:00,600 --> 00:07:03,120 And the answer is no, you do not. 176 00:07:03,120 --> 00:07:05,490 Instead, you just need to know that the higher the G, 177 00:07:05,490 --> 00:07:07,650 such as 4G is higher than 3G, 178 00:07:07,650 --> 00:07:10,290 this means it's a newer standard and it has faster speeds 179 00:07:10,290 --> 00:07:11,580 because that's pretty much what happened 180 00:07:11,580 --> 00:07:12,960 each and every time. 181 00:07:12,960 --> 00:07:14,340 The other thing that's important to remember 182 00:07:14,340 --> 00:07:16,650 is that 5G comes in three different bands. 183 00:07:16,650 --> 00:07:18,780 The low band that's used for further distance 184 00:07:18,780 --> 00:07:21,570 but lower speeds, mid band, which has a good distance 185 00:07:21,570 --> 00:07:23,100 and good speed and high band, 186 00:07:23,100 --> 00:07:26,070 which has a very small distance, but very high speeds. 187 00:07:26,070 --> 00:07:28,680 As you go upward in the band, you get faster speeds, 188 00:07:28,680 --> 00:07:31,170 but you will decrease in your coverage area. 189 00:07:31,170 --> 00:07:32,580 For this reason, you're going to find 190 00:07:32,580 --> 00:07:35,100 that most 5G deployments are going to use those mid band 191 00:07:35,100 --> 00:07:37,470 frequencies, which gives you a good amount of coverage 192 00:07:37,470 --> 00:07:40,650 and pretty high speeds of between 100 and 900 193 00:07:40,650 --> 00:07:42,210 megabits per second. 194 00:07:42,210 --> 00:07:44,280 Now, in terms of cellular technologies, 195 00:07:44,280 --> 00:07:45,870 they are going to operate in one of two 196 00:07:45,870 --> 00:07:47,490 underlying technologies. 197 00:07:47,490 --> 00:07:50,250 These are known as GSM and CDMA. 198 00:07:50,250 --> 00:07:52,350 Which one you're going to use is really going to be determined 199 00:07:52,350 --> 00:07:54,000 by which area of the world you live in 200 00:07:54,000 --> 00:07:56,190 or which cellular provider you're going to be using 201 00:07:56,190 --> 00:07:57,930 in your particular country. 202 00:07:57,930 --> 00:07:59,850 For example, here in the United States, 203 00:07:59,850 --> 00:08:01,980 if you're using T-Mobile or AT&T, 204 00:08:01,980 --> 00:08:04,380 their services rely on GSM. 205 00:08:04,380 --> 00:08:07,650 If you're using Verizon, they normally use CDMA. 206 00:08:07,650 --> 00:08:10,380 If you live outside the US and you're working in Japan 207 00:08:10,380 --> 00:08:12,870 or South Korea, they use CDMA, 208 00:08:12,870 --> 00:08:14,640 but if you're going to be living anywhere else in the world, 209 00:08:14,640 --> 00:08:17,130 most of the time they're using GSM. 210 00:08:17,130 --> 00:08:19,950 So what exactly is GSM and CDMA? 211 00:08:19,950 --> 00:08:23,310 Well, GSM is the global system for mobile communications 212 00:08:23,310 --> 00:08:25,290 and it's a cellular technology that takes your voice 213 00:08:25,290 --> 00:08:27,990 during a call and converts it to digital data. 214 00:08:27,990 --> 00:08:29,670 Then your device is given a channel 215 00:08:29,670 --> 00:08:32,039 and a time slot so the service provider can combine 216 00:08:32,039 --> 00:08:34,260 your call with several other users' calls 217 00:08:34,260 --> 00:08:36,539 to maximize the efficiency of their networks. 218 00:08:36,539 --> 00:08:38,280 So, let's pretend they need to provide service 219 00:08:38,280 --> 00:08:40,200 to four users simultaneously. 220 00:08:40,200 --> 00:08:42,059 They could get each of us a quarter of a second 221 00:08:42,059 --> 00:08:43,620 to transmit our digital data, 222 00:08:43,620 --> 00:08:45,180 and then when it reaches the other side, 223 00:08:45,180 --> 00:08:46,440 it'll be combined back together 224 00:08:46,440 --> 00:08:48,990 and converted back into your analog voice so the person 225 00:08:48,990 --> 00:08:51,390 who you're talking to can actually hear you. 226 00:08:51,390 --> 00:08:53,760 This is actually a form of time division in the original 227 00:08:53,760 --> 00:08:55,860 GSM standard, but it was modified 228 00:08:55,860 --> 00:08:58,320 to different code division methods once 3G networks 229 00:08:58,320 --> 00:09:00,240 were rolled out with GSM. 230 00:09:00,240 --> 00:09:03,120 Now, CDMA, or code division multiple access, 231 00:09:03,120 --> 00:09:06,240 is a cellular technology that uses, well, code division 232 00:09:06,240 --> 00:09:07,740 to split up that channel. 233 00:09:07,740 --> 00:09:09,780 For every call that's made, the data's encoded 234 00:09:09,780 --> 00:09:11,970 with a unique key and then all the data streams 235 00:09:11,970 --> 00:09:14,610 can be transmitted at once in a single channel. 236 00:09:14,610 --> 00:09:16,830 On the other side, the receiver has the unique key 237 00:09:16,830 --> 00:09:19,380 for each call to divide out the combined signal back into 238 00:09:19,380 --> 00:09:22,170 the individual calls so the other side can hear just your 239 00:09:22,170 --> 00:09:24,210 voice during your phone call. 240 00:09:24,210 --> 00:09:26,280 Now, CDMA is actually a more powerful 241 00:09:26,280 --> 00:09:28,740 and flexible technology than GSM is, 242 00:09:28,740 --> 00:09:31,410 and that's why 3G GSM actually introduced 243 00:09:31,410 --> 00:09:34,110 and adopted a lot of parts from CDMA method 244 00:09:34,110 --> 00:09:37,680 and then termed it WCDMA, or wideband CDMA 245 00:09:37,680 --> 00:09:41,760 or UMTS, the Universal Mobile Telephone System. 246 00:09:41,760 --> 00:09:44,400 Now, which one is better, CDMA or GSM, 247 00:09:44,400 --> 00:09:45,840 and which one should you use? 248 00:09:45,840 --> 00:09:48,840 Well before 3G, 4G and 5G networks, 249 00:09:48,840 --> 00:09:50,370 there really was a big difference 250 00:09:50,370 --> 00:09:52,050 between these two technologies, 251 00:09:52,050 --> 00:09:53,910 but ever since 3G was introduced, 252 00:09:53,910 --> 00:09:56,640 we pretty much are all going to be using some form of CDMA, 253 00:09:56,640 --> 00:09:58,920 even if you buy a GSM phone. 254 00:09:58,920 --> 00:10:01,363 The only reason we really bring up this idea of CDMA 255 00:10:01,363 --> 00:10:03,180 and GSM is so that you realize 256 00:10:03,180 --> 00:10:04,620 that there is a difference in support 257 00:10:04,620 --> 00:10:06,720 based on where you're going to live in the world. 258 00:10:06,720 --> 00:10:09,780 As I said, GSM is much more widely supported 259 00:10:09,780 --> 00:10:12,180 across the globe, so if you travel a lot, 260 00:10:12,180 --> 00:10:13,980 you may want to carry a GSM supported 261 00:10:13,980 --> 00:10:15,840 smartphone or hotspot with you. 262 00:10:15,840 --> 00:10:17,310 Remember, it's always important 263 00:10:17,310 --> 00:10:18,420 to check your cellular provider 264 00:10:18,420 --> 00:10:20,460 for hotspot options in the areas you plan to work 265 00:10:20,460 --> 00:10:23,220 out of mostly, or you plan to travel to. 266 00:10:23,220 --> 00:10:24,750 Most smartphones can work 267 00:10:24,750 --> 00:10:26,730 as a hotspot using either tethering 268 00:10:26,730 --> 00:10:29,040 or an internet connection sharing over wifi, 269 00:10:29,040 --> 00:10:31,223 but you can also purchase a dedicated mobile hotspot device 270 00:10:31,223 --> 00:10:33,870 that is a cellular modem and a wireless access point 271 00:10:33,870 --> 00:10:36,540 combined into a single small form factor device, 272 00:10:36,540 --> 00:10:39,480 and I actually carry one of these with me wherever I travel. 273 00:10:39,480 --> 00:10:42,180 Now the other major difference is that with GSM phones, 274 00:10:42,180 --> 00:10:45,120 you have a SIM card to identify yourself to the network, 275 00:10:45,120 --> 00:10:47,640 whereas with a traditional CDMA phone you don't 276 00:10:47,640 --> 00:10:49,500 because CDMA devices are configured 277 00:10:49,500 --> 00:10:51,510 and locked to your cellular provider. 278 00:10:51,510 --> 00:10:54,660 For this reason, a lot of people prefer GSM phones 279 00:10:54,660 --> 00:10:57,210 because you can simply replace your SIM card while traveling 280 00:10:57,210 --> 00:10:59,400 and have a new local service plan for your phone 281 00:10:59,400 --> 00:11:02,970 that's much cheaper than using your American plan overseas. 282 00:11:02,970 --> 00:11:06,090 These days though, most modern smartphones also support 283 00:11:06,090 --> 00:11:08,880 E-SIMs, or electronic SIMs where you simply download 284 00:11:08,880 --> 00:11:10,770 an app from the app store and change your SIM 285 00:11:10,770 --> 00:11:13,290 to a local provider to get the data service you want 286 00:11:13,290 --> 00:11:15,270 as soon as you get off the plane instead of paying 287 00:11:15,270 --> 00:11:17,100 those large international roaming fees 288 00:11:17,100 --> 00:11:19,700 to your cellular provider back in the United States.