Mobile computing has been undergoing          with infrared ports to allow communication
a bit of a renaissance lately. A few years ago   with laptops. Then cell phones started to
it was a simple matter of finding a data-        come with modems built in. The connecting
compatible mobile phone, a PC card               methods     of    mobile      computing,    its
modem, and a matching cable and installing       introduction,    connection    types,   factors
it as a modem. Then people started to use        affecting connections, mobile applications
PDA’s as well. Cell phones started to come       and its limitations are explained.

                                                           Distinction between "wireless"
                                                            and "mobile."
                                                           Mobile Devices
What is mobile computing?                                  Challenges in mobile
 A view on portable devices.                                computing
                                                           Merits and Demerits
                                                           Applications
              Conclusion                              computing. Mobile computing helps users
              Bibliography                            to be productive immediately by reducing
                                                       the training requirements associated with
                                                       traditional   automated     data     collection
                                                       methods and provides a higher level of
                                                       portability than keyboard-based systems.
                                                       Field-based     users     can     access    any
   Wireless     networking     technology     has
                                                       information available from the system at any
   engendered a new era of computing, called
                                                       time to make critical business decisions.
   mobile computing. Mobile Computing is an
                                                       This information is available at the point of
   umbrella term used to describe technologies
                                                       use, wherever and whenever they need it.
   that enable people to access network
                                                       Portable devices like laptop and palm top
   services any place, anytime, and anywhere.
                                                       computers give mobile users access to
   Ubiquitous     computing      and    nomadic
                                                       diverse sources of global information
   computing are synonymous with mobile
                                                       anywhere and at any time.

                                                          for mobile computing has prompted numerous
                                                          hardware and software companies to focus their
                                                          efforts in providing solutions to the vertical, form-
                                                          oriented marketplace.

                                                            Distinction between "wireless" and "mobile."
                                                          Wireless refers to the method of transferring
                                                          information between computing devices, such as a
                                                          personal data assistant (PDA), and

One of the most important and highly publicized
                                                          a data source, such as an agency database server,
recent developments in the PC world has been the
                                                          without a physical connection. Not all wireless
introduction of the pen interface. By using a stylus
                                                          communications technologies are mobile. For
to replace the keyboard, mobile computers are
                                                          example, lasers are used in wireless data transfer
turning thousands of computer illiterate people
                                                          between    buildings,    but
especially those involved with field-based data
                                                          cannot be used in mobile
collection into computer users. The market
potential and breadth of application requirements
communications at this time.                             Here we have seven different types of mobile
Mobile simply describes a computing device that          devices:
is not restricted to a desktop. A mobile device may      Laptop computers
be a PDA, a "smart" cell phone or Web phone, a           PDA’s and handheld PCs
laptop computer, or any one of numerous other            Pagers
devices that allow the user to complete computing        Smart phones and cellular phones
tasks without being tethered, or connected, to a         Task devices, such as bar code scanners
network. Mobile computing does not necessarily            Blue tooth
require wireless communication. In fact, it may not       Bridge
require communication between devices at all.

    Mobile devices

   Laptops are typically used and supported in the    have intense and constant need for time sensitive
same way as desktop PCs. In fact, many                communications.
organizations have replaced desktops with their          Pagers that support one- and two-way text
portable cousins, as the workforce has grown          messaging are also used in similar situations.
increasingly mobile.                                  Third party vendors most often provide support for
   PDA’s, however, are the least planned for and      these devices.
supported devices. They are undergoing rapid              Task devices such as the parcel tracking
evolution and are being brought into organizations    devices used by Federal Express (FedEx) and the
in the same way the earliest PCs were. That is,       United Parcel Service (UPS) delivery personnel
adventurous early adopters buy the devices for        are most often bought as part of a complete system
their personal use and then ask IT departments to     from a third-party vendor. Because they are
integrate the devices into the corporate IT           frequently mission-critical, most corporations
environment.                                          support task devices as rigorously as desktop
   Smart phones that allow users to access phone      computers.
calls, two-way radio transmissions, and paging and       Bluetooth:- A short-range wireless standard that
data transmissions on one device are also finding     specifies radio connections between devices within
applications in hospitals and other situations that   a 10-meter range of     each other. Bluetooth is
                                                      designed as a Personal Area Network (PAN, or
WPAN for "Wireless Personal Area Network")               device weight,      battery power,         screen size,
technology with a wide variety of theoretical uses.      portability, quality of radio transmission, error
   Bridge:- A device that connects two local-area        rates. Mobility brings additional uncertainties, as
networks (LANs), or two segments of the same             well as opportunities to provide new services and
LAN. Bridges simply forward packets from one             supplementary information          to     users    in   the
segment to another without analyzing or routing          locations where they find themselves.
messages. This allows them to connect dissimilar         The major challenges in mobile computing are
networks (e.g., a bridge can connect an Ethernet         described including: low bandwidth, high error
and Token-Ring network).                                 rate,    power     restrictions,   security,       limited
       Challenges in mobile computing                    capabilities, disconnection and problems due to
Wireless and mobile environments bring different         client mobility.
challenges to users and service providers when
compared to fixed, wired networks. Physical
constraints become much more important, such as

        Low Bandwidth                                 network     connections.       The        wireless
   Wireless networks deliver lower bandwidth           environment exhibits higher error rates,
   than wired networks. As a result, mobile            which results in retransmission and affects
   applications have to be carefully designed to       the Quality of Service. By minimizing the
   control    the     bandwidth        consumption.    usage of wireless transmission, the data is
   Software techniques required to improve             less exposed to transmission errors. In
   effective bandwidth usage include data              addition, error correction schemes can be
   compression logging requests to combine             employed     to      improve     performance.
   multiple short ones, lazy write back,               However, these schemes also add to the
   difference-based         updates,       caching,    communication overhead and reduce the
   prefetching,     usage   of    proxy,    priority   usable bandwidth.
   scheduling, etc.                                        Power Limitations
                                                       Mobile computers are concerned with the
        High Error Rate                               limited power supply, an issue that does not
   The network quality varies as the mobile            appear in distributed wired environment.
   computer moves across the heterogeneous             Hardware improvements on batteries can
help to lengthen the life of a charge and              Security
reduce battery weight. In addition, efficient     Security and privacy are of specific concerns
software operations can help to lower the         in wireless communication because of the
power consumption. Examples include:              ease of connecting to the wireless link
shifting the processing to a fixed host,          anonymously.      Common          problems     are
aggressively caching and prefetching data to      impersonation,     denial    of     service   and
reduce disk traffic, and transmitting less data   tapping. The main technique used is
while receiving more                              encryption. In personal profiles of users are
                                                  used to restrict access to the mobile units.

Merits                                               Improving information flow
                                                     Allowing faster adaptation to changing
The benefits of automating data collection           business conditions
applications with mobile computing are the           Increasing responsiveness and customer
reduction    of   hard    and    soft    costs,      satisfaction
enhancement of revenue potential, and a              Providing       access      to     previously
distinct competitive advantage through:              unavailable information
   Improving the data collection process
   Improving data accuracy                           Demerits
   Reducing paperwork
                                                  The demerits of the mobile computing are
   Enforcing collection of more complete
                                                  discussed as follows:
   Facilitating collection of more useful
                                                     Information access via a mobile device
                                                     is plagued by low available bandwidth,
   Eliminating redundant data entry
                                                     poor    connection       maintenance,      poor
   Reducing administrative costs
                                                     security,     and    addressing     problems.
   Reducing billing errors
                                                     Unlike their wired counterparts, design
   Reducing data backlog
       of software for mobile devices must                 themselves. In general, most application
       consider resource limitation, battery               software,     operating     systems,        and
       power and display size. Consequently,               network infrastructures are intended for
       new hardware and software techniques                more conventional environments, and so
       must   be     developed.    For   example,          the mobile, wireless user has great
       applications need to be highly optimized            difficulty exploiting the computational
       for space, in order to fit in the limited           infrastructure as fully as he or she might.
       memory on the mobile devices.                       There is an emerging consensus among
       Mobility brings additional uncertainties,           researchers that a new architecture and
       as well as opportunities to provide new             dynamic infrastructure is an appropriate
       services and supplementary information              way to address this problem.
       to users in the locations where they find

       Day by day as the standard of the mobile            Vertical industries where mobile technology has
computing is increasing the boons of mobile                already     been    successfully    adopted       include
computing are changing to banes. Eg: The most              Consumer Goods, Delivery and Route Sales,
deadly terrorist attack occurred on sept 11, 2001.         Government,        Healthcare,     Market     Research,
                                                           Pharmaceuticals, Transportation, and Utilities.
    Applications
       New         technical      and        application
                                                           Consumer Goods. Typical applications include
       developments have established that mobile
                                                           inventory, merchandising, order entry, and sales
       systems can be a cost-effective, efficient,
                                                           automation. Features found in these applications
       and productive solution in several different
                                                           usually provide access to stock and pricing
       types of application environments. They
                                                           information, monitor promotions, and perform
       are:- a new generation of satellites,
                                                           shelf space analysis including number of facings
       especially     Low-Earth      Orbit      systems
                                                           and product age. Customer detail helps reps to act
       (LEOS) are under development with the
                                                           more as consultants than order takers.
       Internet in mind. Companies like Teledesic
       and Orbcomm             are actively promoting
                                                           Delivery & Route Sales. With fierce competition
       Internet access.
                                                           and an increasing inventory, having timely and
                                                           accurate information is more important than ever.
Government.        Applications       center     around       Market Research. Automating the survey process
assessments, inspections, and work orders. Most of            has enabled these companies to get their data more
these applications involve auditing some sort of              accurately and quickly while being able to
facility or process (food service, restaurant,                customize their queries at will.
nursing home, child care, schools, commercial and             Pharmaceuticals. In addition to the reps need to
residential buildings).                                       perform account management and call reporting
                                                              functions, the FDA’s requirement for physician
Healthcare. The focus in this industry has been on            signatures for all drug samples dispensed was an
automating patient records, medication dispension,            added complication that was eliminated through
and sample collection. A common goal is to                    the use of mobile technology.
leverage mobile computing in the implementation
of positive patient identification.

   Transportation.        Transforming         freight    to perform inspections on a routine basis.
   damage inspections from paper to mobile
   computing greatly expedites the process and                            Conclusion
   reduces costs by providing on-line pre-                 Mobile computing is rapidly becoming
   shipment inspections. This technology also              popular, and user demand for useful wireless
   offers a more efficient means of storing and            applications is increasing.
   transmitting maintenance inspection reports.            Additionally, this paper shows how these
   In conjunction with GPS (global positioning             behavioral extensions serve as a powerful
   systems),     mobile      computing         allows      abstraction for practical systems.
   companies to provide better customer                    In this paper, we have looked at issues
   service by being continually aware of                   related to portable devices, merits, demerits
   exactly where any given shipment is when                and applications in mobile environment.
   in transit.                                             Because of the banes of mobile computing
                                                           the security level should be improved.
 Utilities. Eliminating the rekeying of data and
 providing a means to perform on site analysis
 are instrumental to an industry that is required
                                         Application design for wireless computing :
                                         M-Mail: A Case Study of Dynamic
                                         Application     Partitioning   in   Mobile
                                         Christine Julien and Gruia-Catalin Roman :
                                         Active Coordination in Ad Hoc Networks
                                         Raymond J. Brunsting : Quality of Service
Terri Watson. : Application design for
                                         Issues in Wireless Networks
wireless computing.