In a wireless network, communication can happen in two ways. In the first method, all wireless devices communicate using a central device, the access point such as a router. This method is called infrastructure mode. In the second method, devices communicate directly with each other without the use of an access point. This method of wireless communication is called ad-hoc networking. Centralization of communication is what differentiates infrastructure mode from the ad-hoc mode.
Use cases of infrastructure mode
Infrastructure mode is very useful networks which are connected to a bigger network via wired connections. A classic example of this can be seen in a house where a small home based WLAN (wireless local area network) is connected to the internet.
Most corporates operate WLANs in infrastructure mode. The ability to connect WLAN to wired LAN is handy as it allows access to services such as data servers and printers.
Setting up infrastructure mode
Setting up a wireless LAN in infrastructure mode requires minimum the installation of a wireless access point (AP). The access point and all the client devices should be configured to the same network name (SSID) to enable communication.
SSID stands for Service Set Identifier which is a unique 32 character ID used to name networks. The access point may or may not be cabled to a wired network. Access to a wired network allows wireless devices to use resources such printers, data servers or the internet.
The wireless network can be extended by adding multiple access points. This will help increase the range of the network and at the same enabling the network to service more wireless clients.
When a wireless network consists of only one access point along with a set of wireless stations, it is called a Basic Service Set (BSS). When two or more BSSs (each BSS can function as a separate network) combine to form a single network, it is referred to as an Extended Service Set (ESS).
If you have a wireless network set up at home, it would be automatically in infrastructure mode. This is because wireless routers, these days, come with a built-in access point.
Advantages of infrastructure mode over ad-hoc networks
In contrast to infrastructure mode, ad-hoc connects devices in a peer-to-peer manner. This means that you can set up an ad-hoc network without installing an access point. However, infrastructure mode has several advantages when compared to ad-hoc mode.
Scaling of networks
Infrastructure networks, unlike ad-hoc networks, can be easily scaled by connecting to a wired network. This enables a user to connect to a broader network such as an enterprise WAN (wide area network) or internet.
Also, a WLAN can be extended easily by adding multiple access points. This helps to combat congestion in the network and can service a lot more wireless clients.
Infrastructure mode requires fewer resources as compared to an ad-hoc network. This is because, in infrastructure mode, the access point is stationary whereas, in ad-hoc mode, the physical layout of the network keeps changing as devices move around.
Also, in ad-hoc mode, each device creates a connection with every other device. A large number of connections generate more interference than connecting directly to an access point.
Infrastructure mode is primarily used to implement networks that are of a permanent nature. Ad-hoc networks are more beneficial when a temporary connection is required or when you need a small network that does need communication with a larger network.
For example, an ad-hoc network works well when you need to transfer files from one device to another.