1 00:00:01,410 --> 00:00:07,110 Now, some of the basic terminologies, these are going to be very important for us to understand the 2 00:00:07,110 --> 00:00:07,990 following lectures. 3 00:00:08,010 --> 00:00:12,450 So I just want to make sure that we're on a basically same page. 4 00:00:12,450 --> 00:00:20,430 Right, because you're going to hear these concepts in any resource about Wi-Fi networking and of course, 5 00:00:20,430 --> 00:00:21,560 throughout this course. 6 00:00:21,990 --> 00:00:26,850 Now, if you already know the basic terminology, sure, you can go ahead and skip to the next lecture. 7 00:00:28,170 --> 00:00:30,120 So an access point and AP. 8 00:00:31,020 --> 00:00:35,850 This is a device that serves as a central wireless connection point for a Wi-Fi network. 9 00:00:37,600 --> 00:00:40,900 The service set identifier or ID. 10 00:00:42,150 --> 00:00:49,050 It's the name of the wireless network, it can be contained and the beacons sent out by access points 11 00:00:49,620 --> 00:00:56,370 or it can be hidden so the clients who wish to associate must first know the name of the network first. 12 00:00:57,800 --> 00:01:04,460 So early security guidance was to hide the inside of your network, but modern networking tools can 13 00:01:04,460 --> 00:01:09,410 detect the SS ID simply by watching for a legitimate client association. 14 00:01:10,420 --> 00:01:13,510 Because as as IDs are transmitted in clear text. 15 00:01:14,860 --> 00:01:22,630 Besides basic service, that identifier is a unique address that identifies the access point or hub 16 00:01:22,870 --> 00:01:25,060 that creates the wireless network. 17 00:01:26,890 --> 00:01:34,330 The extended service said identifier or E as as ID, it's the name of the wireless network and is used 18 00:01:34,330 --> 00:01:40,420 by all APIs that provide access to the same infrastructure in an extended service said. 19 00:01:41,530 --> 00:01:49,780 It can be advertised by apps and their beacons or suppressed so that clients must know the SS ID before 20 00:01:49,780 --> 00:01:51,520 associating with an app. 21 00:01:53,530 --> 00:01:54,040 Roaming. 22 00:01:55,020 --> 00:02:01,800 So when a wireless network with multiple apps, a client that is moving from the coverage area provided 23 00:02:01,800 --> 00:02:09,540 by one app to that provided by another, it's called roaming, so it must disassociate from the first 24 00:02:09,540 --> 00:02:12,840 AP before it can associate to the next AP. 25 00:02:14,770 --> 00:02:22,930 A channel, this is the network path for wireless transmissions, each Wi-Fi standard has numerous channels, 26 00:02:23,350 --> 00:02:27,190 each of which is a specific central frequency. 27 00:02:28,980 --> 00:02:29,790 Data rate. 28 00:02:30,980 --> 00:02:38,930 The rate in which data can be transferred at any given moment to and from a device, most times the 29 00:02:38,930 --> 00:02:43,580 incoming and outgoing data transfer rates affect each other adversely. 30 00:02:44,510 --> 00:02:50,390 For example, if you're uploading a video while loading a Web page, the Web page will load slower than 31 00:02:50,390 --> 00:02:52,970 usual due to the upload usage. 32 00:02:54,480 --> 00:03:03,450 A beacon is transmitted by an AP 10 times per second, and it advertises the existence of the app on 33 00:03:03,450 --> 00:03:10,710 a particular channel or channels, it includes information needed by clients to associate as well as 34 00:03:11,460 --> 00:03:19,110 it may include the inside the supported channels, as well as data rates and whether it's open or requires 35 00:03:19,110 --> 00:03:20,010 authentication. 36 00:03:22,320 --> 00:03:30,690 Now, decibels can also be used to describe antenna power levels, decibel is the basic unit of measurement 37 00:03:30,690 --> 00:03:32,520 used in Wi-Fi radio signals. 38 00:03:33,740 --> 00:03:41,270 Deb specifies a difference or ratio between the two signal levels and is used to describe the effect 39 00:03:41,270 --> 00:03:44,150 of system devices on signal strength. 40 00:03:45,200 --> 00:03:50,750 So a DBM is the debe value compared to one milliwatt of power. 41 00:03:51,760 --> 00:03:59,680 For example, if the signal power is 100 milliwatt and the reference is one million, the value of the 42 00:03:59,680 --> 00:04:10,300 decibel becomes 20 relative to a milliwatt make sense to our TP link adapters antenna has for DBI signal 43 00:04:10,300 --> 00:04:10,710 power. 44 00:04:11,530 --> 00:04:17,800 Now, a suffix indicates that the reference value is often appended to the decimal symbol. 45 00:04:19,090 --> 00:04:27,910 The suffix is I because I refers to an isotropic antenna, which is equally sensitive to signals from 46 00:04:28,090 --> 00:04:29,590 all directions. 47 00:04:30,750 --> 00:04:38,670 The gain is a key performance number, and this combines the antenna's directive and electrical efficiency 48 00:04:39,390 --> 00:04:46,350 to win a transmitting antenna, the gain describes how well the antenna converts input power into radio 49 00:04:46,350 --> 00:04:49,460 waves headed in a specific direction.