Today, a whole variety of 'mobile computing platforms' such as in-dash VGA displays and automobile computers which feature a variety of applications and functions such as global positioning systems (GPS) and radar detection systems are available for the mass market ("Mobile computing", 2006).
Some mobile computing devices use WLAN (Wireless Local Area Network) as their means to communicate and acquire data. A WLAN is a LAN (Local Area Network) connected through radio or other wireless means. One of the advantages of using a WLAN is the flexibility it offers to overcome restrictions of physically connected networks to space restrictions. It is easy, wire-free and simple to use. WLAN allows data access without having to "jack-in" or plug to a wired network (Shriraghavan et al, 2003).
Wireless Local Area Network (WLAN) transmits and receives data through fixed line network called access points. An area called a "hotspot" results from the area covered by each of the access points. Each access point serves numerous subscribers and they alter their 'access points' as they transfer from one point to another. As the number of access points in a WLAN increases, the size of the network also increases (Shriraghavan et al, 2003).
This type of network uses communications satellites acting as central points for transferring data. The subscriber uses a 'satellite dish antenna and a transceiver to transmit and receive data'. This network is usually a better alternative for rural areas where 'broadband, DSL (Digital Subscriber Line) and cable television' systems are not accessible (Shriraghavan et al, 2003).
The advent of mobile phones or cellular phones ushered in the creation of cellular networks. A cellular network operates by serving different frequencies or bands to handle calls and other services such as short message service (SMS). A cell site is commonly composed of 3 basic parts: a control unit, a receiver and a transmitter connected to a Mobile Telecommunications Center that is also interconnected with the public telephone systems (Shriraghavan et al, 2003).
Ad-hoc and Sensor Networks
An ad-hoc network results from the creation of several small nodes or "motes", tiny powered self-contained computers that are linked through radio around a small area. Motes are capable of communicating and exchanging data with each other over short distances and are usually formed temporarily. Ad hoc networks are common and have several practical military applications (Shriraghavan et al, 2003).
Mobile devices could include the following: Laptop computers, Personal Digital Assistants (PDAs) and handheld PCs, Pagers and cellular phones and task devices, such as bar code scanners. Laptops, PDAs and portable handheld PCs are computing devices that can run a number of programs and applications for every sort of business, enterprise and more recently for the modern home. Laptops are basically portable versions of personal computers (PCs) which equal or even rival the computing power of modern desktop units. They are similarly supported by their manufacturers in the