 Welcome, myself Mr. Vishalangiri, Assistant Professor, Department of Electronics and Telecommunication, Wild-Chain Institute of Technology. Today, we are going to study Communication Technology for IoT, i.e. Wi-Fi. Learning outcome, at the end of this session, students will be able to explain Wi-Fi module. So, before starting with Wi-Fi module, students should know what wireless sensor network is. Now, we will see introduction to Wi-Fi. So, Wi-Fi means wireless fidelity and it is popular wireless networking technology and with the help of this technology, we can exchange the information between two or more devices. So, Wi-Fi will require three main things which are radio signal, antenna and router. So, with the help of these three important things, we can use Wi-Fi technology. Wi-Fi technology will work in two different mode. In first mode, the data can be sent from server to client and in another mode, data can be sent from client to client. So, generally Wi-Fi technology is to be used for computers, laptops but now these days, the Wi-Fi technology is efficiently used by mobile devices for sending and receiving the data. So, generally Wi-Fi is an internet network or network which will have a server and its clients in which data is to be sent to clients and Wi-Fi will have internet connectivity to the device which acts as a slave. So, in the diagram, you can see that there are two laptops. There is one router and a mobile. So, the laptops which will have Wi-Fi module in it can send the data to router and through router, the data is to be sent to the mobile. So, now these days, all the laptops, personal computers as well as smartphones are equipped with Wi-Fi card or Wi-Fi module. So, the mobile present in the diagram can access the data which is present in laptop with the help of Wi-Fi module. So, data in the laptop can also be accessed directly on the mobile if the distance is within the range of that Wi-Fi module and the range can be extended with the help of router present in the diagram. Now, we will see working principle of Wi-Fi technology. So, there is a laptop and that laptop can be connected to personal computer or server or any other device and data can be sent from one device to another device. So, in the working of Wi-Fi, a Wi-Fi card should be present in both the devices between which the communication is going on and the distance is from 10 fits to 150 fits and within that range, the data is to be sent or received from one device to another device. So, while working, the Wi-Fi module should be present in both the devices and the data can be accessed. So, if we want to access internet from one device to another device, we can consider an example of internet provided by Google on railway station now these days. So, one modem is there which will act as a server and to that server number of routers or we can say as a hotspot are to be connected and this is to be used to extend the range and users or passengers which are present at that particular station or platform can access the internet. So, while accessing the internet, the user of a particular smartphone or passenger should have smartphone and Wi-Fi module in that smartphone. So, when the Wi-Fi is turned on, a web page is to be opened and that web page will consist of some information and they will ask you to enter your contact number. So, when we enter the contact number, it will send you a unique code and when we enter that unique code on the web page, the internet is to be connected to a smartphone and now you can use free internet. So, like this connection is to be done between a smartphone and internet provided by the system. Next, security. So, the security is a major issue with the Wi-Fi because if when we are connected with the router and when number of devices are connected to it, so those other devices can access the data like media, contacts and other information which is present in our smartphone. So, the security issue is to be resolved by using these three points. So, first one is use of web page for configuring Wi-Fi security. So, when accessing the Wi-Fi, we can use a web page to configure that Wi-Fi security. And second point is wire equivalence privacy. So, with the help of this wire equivalence privacy, we can configure user ID as well as password and when that Wi-Fi is to be configured with security password, next time when user want to connect with the Wi-Fi, that particular password should be entered on the web page, then only that user can access the Wi-Fi. So, like that security issue is to be resolved in Wi-Fi technology. Now, we will see types of Wi-Fi technologies. First one is Wi-Fi 802.11a which supports bandwidth of 54 mbps and frequency spectrum used is around 5 gigahertz. Second one is Wi-Fi 802.11b which supports bandwidth of 11 mbps and frequency spectrum is around 2.4 gigahertz. Third one 802.11g which supports bandwidth of 54 mbps and frequency spectrum is around 2.4 gigahertz. And last one is Wi-Fi 802.11n which supports 100 mbps bandwidth and frequency spectrum is around 2.4 gigahertz. So, these are the four types of Wi-Fi technologies now these days which are to be used. Now, we will see applications of Wi-Fi technology, browsing internet, computerized applications, video conferences, home appliances, business applications, mobile applications. In these areas Wi-Fi technology is to be used. Advantages, first advantage is wireless laptop are movable. So, the laptops are movable when those are wirelessly connected with the help of Wi-Fi. Reduce cost of wire. So, instead of wire connection if we use wireless connections it will reduce cost of wire. Third one is configuration and setup is easy in case of Wi-Fi technology as compared with cabling process in wire connections. Next one is it is completely safe and it will not interfere with any network. Next we can connect internet via hotspots with the help of Wi-Fi technology and last one is connect internet wirelessly. So, if we want to connect with internet wirelessly we can use Wi-Fi modules. Now, we will see some disadvantages. Wi-Fi generates radiations which are harmful for human health. We must disconnect the Wi-Fi connection whenever we are not using the server that is the next disadvantage. Limits to transfer the data over long distance. So, it will limit to transfer data for long distance communication. Next one is implementation is very expensive when compared to the wired connection. So, these are some disadvantages of Wi-Fi technology. References while preparing this video lecture I have used Internet of Things Architecture and Design Principle by Raj Kamal and second one is Internet of Things for Architects by Perili. Thank you.