Wi-Fi is a wireless standard used on both home and public wireless networks worldwide. (WLAN)
Most modern devices like laptops, netbooks, smart phones etc come equipped with Wi-Fi capability, which you can use to connect the device to home/office and public Wi-Fi networks.
Advantages/Disadvantages of Wi-Fi Networks
Wireless networks are generally cheaper,quicker and easier to set up than wired networks as there are no cables to run.
It is also easier for new devices to join the network as they don’t need to locate a physical access point.
It is for these reasons that Wi-Fi is the main access mechanism, used in home/home office networks.
However in larger buildings it may be difficult to get a signal without using repeaters, and this can then become more complex to setup. See extending a home network.
Wi-Fi is much slower than most wired Ethernet systems, but when the main use is Internet access then this makes no real difference as the Internet connection becomes the limiting factor. See Understanding Internet speeds and speed testing.
Wi-Fi Standards and Speeds
Wi-Fi uses the IEEE 802.11 family of standards.
A typical wireless access point using 802.11b or 802.11g with a stock antenna might have a range of 32 m (120 ft) indoors and 95 m (300 ft) outdoors.
The newer IEEE 802.11n, however, can exceed that range by more than two times (Wikipedea on wi-fi).
802.11b or 802.11g networks use the 2.5GHz carrier frequency while the newer 802.11n networks use the 5GHz frequency.
Devices that support both frequencies (2.5 and 5Ghz)are known as dual band ,and are useful when transitioning from old wireless networks to the newer networks.
Wi-Fi supports three connection modes:
- Infrastructure mode
- Ad-hoc mode
- Direct mode
Infrastructure mode is the most common and it is the mode used in home/business and public Wi-Fi networks.
Infrastructure mode requires a Wireless Access point. On home networks this is usually provided by a Wireless router.
The Access point forms the Wireless network, and all nodes or clients connect to the access point.
The access point, and network is identified by a SSID or service set identifier.
SSID’s are assigned by a network administrator and are usually given easy to remember and descriptive names.
Wireless access points usually broadcast this SSID so that connecting clients can connect to the correct network.
Depending on how it is configured a WAP (Wireless access points ) may broadcast multiple SSIDs.
The screen shot below shows my home network with 2 wireless access points. One of these access point broadcasts 3 SSIDs.
A Wi-Fi access point also has a basic service set ID (BSSIDs) which is used to identify the access point and its clients on a network.
The BSSID is the MAC address of the access point. See this article for more details.
A Wi-Fi access point is also configured to use a preset Wireless channel. Commonly used channels are 1,6,11. See Wiki
If you are responsible for setting up your home Wi-Fi access point /router then you would set up the access point to use a channel that isn’t being used by another access point in your location.
You can use wi-Fi test Apps to see what channels are being used in your location.
It is important to note that Wi-fi channels do not correspond to number of devices that can be connected to the access point.
Each channel corresponds to a frequency that the Wi-fi devices work on, so if your access point is set to use channel 11, then all devices that try to connect to it must also communicate on channel 11.
The number of actual devices that can connect on a given channel is limited by the software on the router and by bandwidth.
Devices on a channel share the channel in a similar fashion to clients on Ethernet networks.
That is each device takes turns sending and receiving data on the channel. (Time slot multiplexing).
Therefore the more clients that are connected the slower each client runs.
This forum discussion goes into more detail.
Most hone networks (802.11b or 802.11g) and devices use the 2.5GHz frequency band while the newer networks (802.11n) use the 5GHz frequency band.
Most new 802.11n support both bands and are known as dual band.
Because of the limited support of the 5GHz band by devices this band is generally quite clear. It also has more channels available.
Ad Hoc Networks
Conventional infrastructure mode relies on a access point through which all nodes on the wireless network communicate.
In addition a node can only be connected to one access point at a time.
With an Ad Hoc network nodes can communicate with each other without an access point.
Ad Hoc Wi-Fi networks will become very important as mesh networking evolves.
Wi-Fi direct allows you to connect two Wi_Fi equipped devices together without requiring an access point.
Essentially it works the same ways as Bluetooth but is much faster and is designed to be used for the same type of applications.
Here is a video from the Wi-Fi Alliance that explains how it works.
Here is a very good article that explains ad-hoc and wi-fi direct in more detail
This Samsung support articles show how to connect wifi direct devices
Secured Wireless (Wi-Fi)
It is common for many home networks and business networks to only allow their own authorized devices to use their wireless network.
This is achieved by securing the network.
The most common mechanism uses encryption using WEP (Wired Equivalent Privacy) or the newer WPA2
Common Wi-Fi Devices
Wireless Access Point-
Creates or extends a wireless network and Connects Ethernet devices to the network.
Most have several Ethernet ports.
Very rarely used as most small networks use Wireless Router provided by their ISP (Internet service Provider)
Looks Similar to the WAP (above) but has a DSL connection to connect to the Internet in addition to the Ethernet ports and Wireless Access point.
Wi-Fi Range Extender/Repeater
Place in range of the existing Wireless network, and it will take the signal from the network and rebroadcast it, thus increasing the range of the network.
Modern ones plug directly into a mains socket and require no other connections. See Powerline Networks
Wireless (WI-FI) is available in many locations both public and private, however because of its restricted range it is not as reliable a connection mechanism as 3G and 4G.
A hotspot is a location that offers Wireless (Wi-Fi) access. They are found in offices/homes that use Wi-Fi and in public locations like bars, airports and train stations.
Wi-Fi has a range of around 35m indoors (802.11n) which means that you will need to be close to the WI-Fi transmitter to get a connection. See Public and Mobile Wi-fi Networks
Related Tutorials and Useful Resources:
- How to Setup A Secure Wireless Network
- Overview of Wireless Technologies for the IOT
- How to setup your Home Router
- Extending a Home network
- BT Wi-Fi and Fon Network Overview