Wireless Terminology

• Station (STA)
• Wireless access point (AP)
• Independent basic service set (IBSS)
• Basic service set (BSS)
• Distribution system (DS)
• Extended service set (ESS)

Station(STA)

• Any client device in a network such as a laptop. In a wireless network, the STA communicates with the AP (access point).
• The wireless STA contains an adapter card, PC Card, or an embedded device to provide wireless connectivity.
• Any Network card (NIC card)

Independent Basic Service Set (IBSS)

• An IBSS is a wireless network, consisting of at least two STAs but no AP.
• When two computers want to communicate directly with one another, they do so in the form of an ad hoc network. Ad hoc networks don’t require a central device to allow them to communicate. Rather, one device sets a group name and radio parameters, and the other uses it to connect. This is called a Basic Service Set (BSS), which defines the area in which a device is reachable. Because the two machines don’t need a central device to speak to each other, it is called an Independent Basic Service Set (IBSS).

Basic Service Area (BSA)

• The coverage area of the AP is called a Basic Service Area (BSA), which is also sometimes known as a wireless cell.
• A BSS is a wireless network, consisting of a single wireless AP supporting one or multiple wireless clients.

Distribution System (DS):

• A system to interconnect a set of Basic Service Sets
• Integrated; A single Access-Point in a standalone network
• Wired; Using cable to interconnect the Access-Point
• Wireless; Using wireless to interconnect the Access-Points

Extended Service Area (ESA)

• When more than one AP is connected to a common distribution system 
• BSS +BSS = ESS
• Why would you want more than one AP connected to the same LAN? There are a few 

Reasons: 

• To provide adequate coverage in a larger area.
• To allow clients to move from one AP to the other and still be on the same LAN.
• To provide more saturation of APs, resulting in more bandwidth per user. 

802.11 Architecture:




Service Set Identifiers (SSID):
The SSID is a name configured on the wireless AP (for infrastructure mode) or an initial wireless client (for ad hoc mode) that identifies the wireless network. The SSID is periodically advertised by the wireless AP or the initial wireless client using a special 802.11 MAC management frame known as a beacon frame.

802.11 Operating Modes:
IEEE 802.11 defines the following operating modes:

• Infrastructure mode : In infrastructure mode, there is at least one wireless AP and one wireless client
• Ad hoc mode : Wireless clients communicate directly with each other without the use of a wireless AP