Similar to a wired Ethernet network, a wireless LAN sends data in packets. Each adapter has a permanent, unique ID number that serves as an address, and each packet contains the data as well as the address of the recipient and that of sender. When it detects a pause, it sends the packet. If it senses other data on the radio frequency, it waits for a moment and then checks again. In an infrastructure topology, each PC sends data to and receives data from an access point, which is mounted on a wall or ceiling and usually looks like a small box with an extended antenna.
Access points in an infrastructure network offer greater range, but the extra equipment costs more.
While all wireless LANs work on these common principles, the speed at which they transmit data and the frequencies they use differ, depending on which standard they follow. Unfortunately, these standards don't work with one another, and all the adapters on your network must adhere to the same standard. All the standards call for adapters to use a small segment of the 2.4-GHz radio band, leaving them with little radio bandwidth for sending data. Frequency hopping spread spectrum rapidly sends part of each data packet across several adjacent radio frequencies, one right after the other, until the entire message has been sent. The speed at which these hopping signals change frequency provides a measure of security, because most radios can't follow them.