PEAP). The billing of QoS is in the home network. A MS roaming from one access point to another often interrupts the flow of data between the MS and an application connected to the network. The MS, for instance, periodically monitors the presence of alternative APs (ones that will provide a better connection). At some point, based on proprietary mechanisms, the MS decides to re-associate with an AP having a stronger wireless signal. The MS, however, may lose a connection with an AP before associating with another access point. To provide reliable connections with applications, the MS must generally include software that provides session persistence. External roaming: The MS (client) moves into a WLAN of another wireless Internet service provider (WISP) and takes their services. The user can use a foreign network independently from their home network, provided that the foreign network allows visiting users on their network. There must be special authentication and billing systems for mobile services in a foreign network. See also Wireless WAN Indoor positioning system References Wireless networking American inventions Local area networks