Wireless Local Area Networks - WLAN

Local area networks (LANs) were the simplest computer networks. Their distinctive features, as a variety of computer networks, consisted in a limited number of nodes (on the order of units), a small distance between interconnected computers (the territory of one building, floor, office), the presence of autonomous communication lines between network nodes (usually wired - cable). The original topology of local networks was the simplest and consisted of connecting network nodes (computers) to a common wired line called a bus .The list of typical LAN features that have survived to this day includes the limited number of network subscribers, the limited territory within which the subscribers are distributed, and the presence of a telecommunication line between subscribers (nodes). In modern LANs, the original features have changed in three aspects: what is wlan

1) changes in the topology of communication lines (in comparison with the topology of the "bus" type);

2) changes in the type of network nodes (along with computers, network nodes can be devices with various types of digital content: video, graphics, telephony, etc.);

3) the introduction of interconnection between the LAN (including all its nodes) and the backbone network, which is used to interconnect networks for various purposes (in particular, other LANs).

The last of the listed aspects is associated with the acquisition by modern LANs of qualitatively new properties in comparison with their original purpose, namely, due to the relationship with the backbone network, the LAN has acquired the ability to perform the functions of an access network to the backbone network . The functions of the interface between the LAN and the backbone network are performed by one of the LAN nodes, which includes a Network-Interface Controller-NIC.

Wireless LANs (Wireless LAN - WLAN) differ from wired ones in that the communication between the nodes of the network is carried out using radio signals. The nodes include transmitting and receiving devices. The environment in which the nodes are located is the propagation environment for radio signals. As a result, the need for wired lines is eliminated. The role of the hub wired LAN performs an access point (Access Point - AP) WLAN.

Wireless connection to the backbone network can be used not only in relation to individual subscribers, but also in relation to group subscribers, which are wired LANs .

The need and expediency of using wireless LANs along with wired LANs is due to the advantages that are achieved by the lack of wired connections. These benefits appear in the following circumstances:

1) the need to create a LAN between nodes separated by natural and artificial obstacles (for example, water obstacles, walls of houses, floors);

2) the need to ensure the mobility of nodes united in a local network;

3) the need to gain access to the backbone network with access to the Internet network in public places of short-term stay (hotels, train stations, reading rooms of libraries, etc.).

The demand for wireless local communication (from a consumer point of view) determines the place of WLAN in modern wireless telecommunications. The most important consumer property of WLAN, along with the convenience of their deployment to ensure the mutual connection of subscribers, is to provide subscribers with access to backbone networks. The latter, in particular, explains the use of the English term " hotspot" for public WLAN deployments with Internet access.