Infrastructure vs Ad Hoc Mode

Infrastructure mode: stations communicate with one or more access points that are connected to the wired infrastructure.

• What is deployed in practice?

Two modes of operation:

• Distributed Control Functions - DCF.

• Point Control Functions – PCF.

• PCF is rarely used - inefficient.

The alternative is “ad hoc” mode: multi-hop, assumes no infrastructure.

• Rarely used, e.g. military.

• Hot research topic!

Ad-hoc mode: no fixed network infrastructure.

• Based on an Independent BSS.

• A wireless endpoint sends and all nodes within range can pick up signal.

• Each packet carries destination and source address.

• Effectively need to implement a “network layer”.