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ABSTRACT
This paper introduces Mobile Computing. A technology that allows transmission of data, via a computer, without having to be connected to a fixed physical link. MOBILE computing has become a reality thanks to the convergence of two technologies: the appearance of powerful portable computers and the development of fast reliable networks
Definition:
A technology that allows transmission of data, via a computer, without having to be connected to a fixed physical link.
Mobile Voice communication is widely established throughout the world and has had a very rapid increase in the number of subscribers to the various cellular networks over the last few years. An extension of this technology is the ability to send and receive data across these cellular networks. This is the principle of mobile computing.
Mobile data communication has become a very important and rapidly evolving technology as it allows users to transmit data from remote locations to other remote or fixed locations. This proves to be the solution to the biggest problem of business people on the move - mobility.

Natural Evolution of Computing
Mobile Computing & wireless Communications
Wireless Communications Mobility Portability
Quality of connectivity Location transparency Power limitations, storage
Bandwidth limitations Location dependency Display, processing,
Classes of Mobile Devices
Display Only
Info Pad model: limited portable processing
Constrained to operation within prepared infrastructure, like a cordless phone
Advantages w.r.to power consumption, upgrade path, lightweight, impact of lost/broken/stolen device
Laptop Computer
ThinkPad model: portable processing, operates independently of wireless infrastructure
Disadvantages: power consumption, expensive, loss exposure, typically greater than 5 pounds
Personal Digital Assistant
Somewhere between these extremes
Wireless Communications
Harsh communications environment
Lower bandwidth/higher latency (good enough for videoconferencing)
Higher error rates
More frequent disconnection
Performance depends on density of nearby users but inherent scalability of cellular/frequency reuse architecture helps
Connection/Disconnection
Network failure is common
Autonomous operation is highly desirable (Caching is a good idea, e.g., web cache)
Asynchronous/spool-oriented applications, like mail or printing
Disconnected file systems: CODA (CMU), Ficus (UCLA)
Low Bandwidth
Orders of magnitude differences between wide-area, in building wireless
Variable Bandwidth
Applications adaptation to changing quality of connectivity
High bandwidth, low latency: business as usual
High bandwidth, high latency: aggressive prefetching
Low bandwidth, high latency: asynchronous operation.
Wireless Communications Bandwidths and Latencies
EXISTING CELLULAR NETWORK ARCHITECTURE
Mobile telephony took off with the introduction of cellular technology which allowed the efficient utilization of frequencies enabling the connection of a large number of users. During the 1980's analogue technology was used. Among the most well known systems were the NMT900 and 450 (Nordic Mobile Telephone) and the AMPS (Advanced Mobile Phone Service). In the 1990's the digital cellular technology was introduced with GSM (Global System Mobile) being the most widely accepted system around the world. Other such systems are the DCS1800 (Digital Communication System) and the PCS1900 (Personal Communication System).
DATA COMMUNICATIONS
Data Communications is the exchange of data using existing communication networks. The term data covers a wide range of applications including File Transfer (FT), interconnection between Wide-Area-Networks (WAN), facsimile (fax), electronic mail, access to the internet and the World Wide Web (WWW). Data Communications have been achieved using a variety of networks such as PSTN, leased-lines and more recently ISDN (Integrated Services Data Network) and ATM (Asynchronous Transfer Mode)/Frame Relay. These networks are partly or totally analogue or digital using technologies such as circuit - switching, packet - switching e.t.c.
Heterogeneous Wireless Overlay Networks
Mobility
Address Migration
Existing applications send packets to a fixed network address
Need to support dynamically changing local addresses as mobile device moves through network
Mobile IP specification: home environment tracks mobile deviceâ„¢s current location through registration procedure
Route optimization: exploit local caches of <global destination node addresses, current care-of address>
Location updates: (Forwarding, Hierarchical mobility agents)
Mobility: IP Routing
Mobility: Mobile IP
APPLICATIONS OF MOBILE COMPUTING
The question that always arises when a business is thinking of buying a mobile computer is "Will it be worth it?"
In many fields of work, the ability to keep on the move is vital in order to utilize time efficiently. Efficient utilization of resources (i.e.: staff) can mean substantial savings in transportation costs and other non quantifiable costs such as increased customer attention, impact of on site maintenance and improved intercommunication within the business.
The importance of Mobile Computers has been highlighted in many fields of which a few are described below:
Application in Real World
For Estate Agents
Emergency Services
Police Incident Information Screen
In courts
In companies
Stock Information Collation/Control
Credit Card Verification
Taxi/Truck Dispatch
Electronic Mail/Paging
Challenges Of Mobile Computing
Prototyping: In the area of data dissemination, many theoretical studies, simulations, and focused implementations have been tried. However, a full scale prototype that encompasses all of the main ideas is still missing.
Bandwidth utilization: A comprehensive study that analyzes the best way to divide the bandwidth between all the options (data broadcast, indexes, invalidation reports, answers to queries and uplink capacity) is needed.
Transactional properties: More work is needed in studying real cases where transactional properties are needed in mobile applications. Moreover, studying which properties can be effectively relaxed for real applications, as long as effective protocols to enforce the remaining properties is an area that could have a very practical impact in the field.
Optimization of location dependent query processing: Very little has been done in finding ways to obtain quick, and perhaps approximate, answers to these queries.
Data visualization: A key issue is to effectively use the scarce display space in mobile computers to present answers to queries.
9.Mobility and Portability
Mobility
Location Dependent Services
Discovery: What services exist in my local environment? e.g., printers file and compute services, special local applications, etc.
Follow me services: Route calls to my current location, Migrate my workstation desktop to the nearest Workstation screen
Information services:
Broadcast/push information (e.g., Flight 59 will depart from Gate 23)
Pull information (e.g., What gate will Flight 59 depart from?)
Service migration: computations, caches, state, etc. follow mobile device as it moves through the network
Privacy: what applications can track user locations?
Portability
Low Power
Limited compute performance
Low quality displays
Loss of Data
Easily lost
Must be conceived as being network-integrated
Small User Interface
Limited real estate for keyboards
Icon intensive/handwriting/speech
Small Local Storage
Flash memory rather than disk drive

Summary
The Future:
With the rapid technological advancements in Artificial Intelligence, Integrated Circuitry and increases in Computer Processor speeds, the future of mobile computing looks increasingly exciting. With the emphasis increasingly on compact, small mobile computers, it may also be possible to have all the practicality of a mobile computer in the size of a hand held organizer or even smaller.
Use of Artificial Intelligence may allow mobile units to be the ultimate in personal secretaries, which can receive emails and paging messages, understand what they are about, and change the individualâ„¢s personal schedule according to the message.
Indeed, technologies such as Interactive television and Video Image Compression already imply a certain degree of mobility in the home, i.e. Home shopping etc. Using the mobile data communication technologies discussed, this mobility may be pushed to extreme. The future of Mobile Computing is very promising indeed, although technology may go too far, causing detriment to society.