Wireless Modes of Operation

WLANs can use one of two modes:

• Ad hoc mode: With ad hoc mode, a wireless device wants to communicate with only one or a few other devices directly, usually for a short period of time. In these cases, the devices send WLAN frames directly to each other.

• Infrastructure mode: In infrastructure mode, each device communicates with a wireless access point (AP), with the AP connecting via wired Ethernet to the rest of the network infrastructure. Infrastructure mode allows the WLAN devices to communicate with servers and the Internet in an existing wired network.

  Infrastructure mode supports two sets of services, called service sets. The first, called a Basic Service Set (BSS), uses a single AP to create the wireless LAN. The other, called Extended Service Set (ESS), uses more than one AP, often with overlapping cells to allow roaming in a larger area.