Maximum Speeds vs. Real World Speeds
When you shop for wireless networking hardware you will typically see the equipment's top speed listed on the web site or on the packaging at the store. You should realize that the top speed is rarely, if ever, achieved.
It's not uncommon, in an average-sized home, to see 802.11b equipment, with a top speed of 11 megabits per second, averaging 3–4 megabits per second. That's still likely faster than your cable or DSL modem Internet connection. In a home environment this is plenty of bandwidth for typical applications like surfing the Internet, printing, and copying MP3 files from one computer to another.
In my own home, I've found that 802.11a equipment (with a top speed of 54 megabits per second) often operates at less than half that speed. With the addition of an access point, the speed halves again because of the roundtrip communication between network adapter and access point (see Figure 3.7).
Figure 3.7. When you add an access point, the network adapter's radio sends and receives data from the access point.
The data sent over your network includes more than just the files you are downloading from the Internet, or copying from one computer to another. Data also needs to be transferred that includes information on how and where the data is supposed to arrive, as well as confirmation that the data has reached its destination. This extra data, along with potential interference from other wireless devices, and network latency make it difficult to reach the theoretical maximum speeds of wireless connections.