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Mobile computing is the term describing the technology while moving, which are opposite to portable computers. This technology gives the opportunity to use the standalone computers capable of
â€¢ storing large amount of software and data files,
â€¢ processing power to support the required applications.
Whenever we are static, connect to internet through an access point and we can transfer file, browse, telnet etc. While we are moving connectivity is a problem in mobile computing. We can use cellular mobile for connecting to any network service provider. Mobile computing device acts as remote terminal. Actual Mobile computer - somewhere in between the two
â€¢ Issues due to
â€¢ nature of medium
Mobile computing systems have different constraints and hence different solutions. Main challenges are due to
Wireless - unreliable.
Mobility - dynamism of information.
Portability - limited resources.
Requirements for mobile services are stability, bandwidth/cost considerations, and integration into the familiar environment, application transparency, security and extendibility. To address Connection management, Line parameter management, caching, Authentication and encryption, Localization management, Accounting, Profiling there is an architecture called mobile service architecture.
MOBILITY SERVICE ARCHITECTURE:
Mobility services can be classified into three groups. First service is to overcome the common restrictions of mobile computing, which arise mainly from the slowness, insecurity and instability of wireless. These services are called common mobility services (CMS). Examples are connection management, caching or encryption services. The second group of services handles the management and administration of mobile users moving around and connecting their portables to networks at different places. These mobility management services (MMS) include tasks like authentication of users, accounting and billing issues or profiling of the users' habits. The another set of tasks which are necessary to adapt certain existing applications to mobile usage are implemented by high level services, are called special mobility services (SMS). Special mobility services adapt existing services to the mobile conditions.
Using HTTP with wireless communication over slow and expensive lines produces long times of opened connection high costs. Mobile-WWW introduces an extension for HTTP which uses an intelligent compression and administration mechanism to save connection time and money. The quality of service in web-client which is the special type of Mobile-WWW is defined according to the users preferences, the available bandwidth and the cost of transmission. The server compresses the data in accordance to the values of the quality of service. For text and hyper text compression we are using a Huffman code with dictionaries installed on every participating system.
Mobile devices - namely PDAs like Apple Newton, Psion and WindowsCE systems - are small in size and their usually weak computing power if compared to stationary computer systems. These restrictions (among others, e.g. weak displays etc.) lead to a number of classes of applications, which are especially well suited for being used with PDAs. Among the typical applications used with PDAs in every-day scenarios are "Notepad", "Address Book", "Calendar", "Communication" (by email), and "Information Retrieval" (by the means of the WWW). These applications can be found on almost every PDA by default.
The programs which are used in mobile devices like mobile phones, laptops, palm computers, etc. for internet connectivity and other computer related activities are called mobile computing applications. The various issues and designs of mobile computing application are discussed under various headings below.
Technical Design Issues consist of network design, capacity planning, response time calculations, data compression considerations, system availability design and security issues. The technical design plays a key role in a mobile computing project.
Issues regarding Wireless LAN design and Wide Area Radio Network Design which network design comprises are discussed below.
a. Wireless LAN design issues
The number of mobile users who will use wireless LAN and the number of them active during the peak period.
The types of LAN application accessed by them. (Wireless LAN is slower than wired LAN connectivity).
Roaming areas, location & range of needed access point.
Preferred technology-spread spectrum or frequency hopping.
Radio frequency interference from any other devices in office, factory or campus etc.
b. Wide Area Radio Network Design Issues
The need of building a private radio network.
Matching of user application-usage profiles to a given network capacity.
Integration of RNA technology with a radio network infrastructure.
Ensuring good coverage & minimum number of dead spots.
c. Security issues:
It is tough to track down securing information by unauthorized access. Common security breaches of mobile computing applications include,
Network by criminal elements.
Physical breach security at communication centers mainly unmanned base stations.
Interception of credit card authorization over wireless network.
Careful security considerations including on-the-air encryption & firewalls must be used.
Other than technical design the next major issue under Mobile computing application is Ergonomics & Logistics Design where the designers evaluate the following.
Form factor of end user device
Input method-keyboard, pen, touch or voice
Whether Portable or fixed
Safety & Health issues.
B.Tech, 3rd year, CSE.