Basic service set:-
The set of all stations that can communicate with each other along with the associated AP is called BSS or the Basic service set. Each BSS has an identification (ID) called the BSSID, which is also the MAC address of the access point (in the infrastructure BSS).
BSS could be divided into two types:
1) Independent BSS (also referred to as IBSS)
2) Infrastructure BSS.
An zz is an ad-hoc network that contains no access points, which means they cannot connect to any other basic service set, whereas in an Infrastructure BSS is the one which is organized around an Access Point which can bridge traffic out the BSS onto a distribution network.
Extended service set:-
The set of all connected Base Service Stations (BSS) is known as an Extended Service Set (ESS). Access points in an ESS are connected by a distribution system. Each ESS has a ID called the SSID which is a 32-byte (maximum) character string.
The Distribution System connects the Access points in an ESS. The concept of a DS can be used to increase network coverage through roaming between cells.
Peer-to-Peer or ad-hoc wireless LAN:-
An ad-hoc network is a network where stations communicate only with each other. There is no Central Access Point involved. On the other hand, A peer-to-peer (P2P) network allows wireless devices to directly communicate with each other. Wireless devices within range of each other can discover and communicate directly without involving central access points. This is accomplished using the Independent Basic Service Set (IBSS). This method is typically used by two computers so that they can connect to each other to form a network.
The 802.11 has two basic modes of operation:
i) ad hoc mode and ii) infrastructure mode.
In ad hoc mode, mobile units transmit directly peer-to-peer. In infrastructure mode, mobile units communicate through an access point that serves as a bridge to a wired network infrastructure. Since wireless communication uses a more open medium for communication in comparison to wired LAN's, the 802.11 designers also included shared-key encryption mechanisms to add a layer of security: Wired Equivalent Privacy (WEP), Wi-Fi Protected Access (WPA, WPA2).
A bridge is a hardware device which is used to connect different types of networks. For eg, A wireless Ethernet bridge allows the connection of devices on a wired Ethernet network to a wireless network. The bridge acts as the connection point between the Wired and the Wireless LAN.