TKK | Tietoverkkolaboratorio | Opetus
A WLAN can be set up in two main architectures: Ad-hoc (distributed control) and infrastructure LAN (centralized control).
The ad-hoc network (also called peer to peer mode) is simply a set of WLAN wireless stations that communicate directly with one another without using access point or any connection to the wired network. For example, this ad-hoc network can be formed by two laptops with a network interface card. There is no central controller; mobile terminals can communicate using peer-to-peer connections with other terminals independently. The network may still include a gateway node to create an interface with a fixed network. As an exaple this kind of setup might be very useful in a meeting where employees bring laptop computers together to communicate and share information even when the network is not provided by the company. Or an ad-hoc network could be set up in a hotel room or in the airport or where the access to the wired network is barred.
Fig 1. Ad-hoc network setup. Reference:Designing a high performance Radio Local Area Network adapter.Juha Ala- Laurila .Master thesis 1997, Tampere University of Technology p.84.
The infrastructure LAN network consists of an arbitrary number of mobile terminals in addition to access points. The access points are located between mobile terminals and the fixed network. All data transmission is controlled and conveyed by the access points and they are also responsible for sharing resources between terminals. The range of an access point using radio frequencies is roughly 100 meters. The range varies widely with the geometry and other physical properties of the space in which it is used.
Fig 2.Infrastructure LAN network setup. Reference:Designing a high performance Radio Local Area Network adapter.Juha Ala- Laurila .Master thesis 1997, Tampere University of Technology p.84.