The access range between a mobile terminal and an access point will be somewhere between 100m, if there are few obstructions, and 30m or less in an urban environment. Within a building the range may be 10m, or less, if there are walls between the mobile terminal and the access point.
As the distance between a mobile terminal and its current access point increases, so, typically, the data rate supported by the radio link will drop. The sequence of link speeds defined for 802.11b is 11 Mbs-1, 5.5 Mbs-1, 2 Mbs-1, 1 Mbs-1, 0.5 Mbs-1.
802.11b and 802.11g both use unprotected and unlicensed8, but regulated9, spectrum in the 2.4 GHz ISM10 band. However users of this allocation have no rights of protection against interference from other users, and must accept any interference which is received. Other users of this spectrum include microwave ovens and Bluetooth.
The 5 GHz spectrum used by 802.11a enjoys a similar licensing régime.