The cell phone is one of the most popular mobile devices.
It has constantly evolved since its invention, on the one
hand, we have the emergence of intelligent mobile phones
(smartphones), which have integrated the functions of PDA
(Personal Digital Assistant) in conventional mobile phones,
and on the other, they have been endowed with more computing power and more interfaces for communication [6, 2].
It's common that current mobile devices have two or more
communication interfaces such as USB, infrared, Bluetooth,
GPRS and the IEEE 802.11, popularly known as Wi-Fi.
Wireless networks improve the utility of portable computing
devices, enabling mobile user's versatile communication and
continuous access to services and resources of the terrestrial
networks [1]. These technologic developments allow current
mobile devices to run applications that generate a large number of file and, as a consequence, require a greater storage
capacity. Unfortunately, the storage capacity on these devices has not grown at the pace that mobile applications
require.
The storage limitations reduce the mobility and storage
capacity of users, particularly in situations when users are
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travelling and they need more space to keep, for instance,
their pictures or videos and there is not available a nearby
external storage device (eg. a computer). This kind of situations motivated the development of mechanisms that allow
file to be exchanged between mobile devices and external
storage systems in a transparent way, taking into account
situations such as LAN or WAN wireless connectivity, cost
of the service and available storage.