1. Mobile Computing

2. Mobile (nomadic) computing is concerned with the connection of portable (mobile) computers, and with the migration of software, from a home platform to a remote one;

3. It is now recognized that access to computing and communications is necessary not only from one's "home base," but also while one is in transit and when one reaches one's destination.
The goal of "transparent virtual networking" or "nomadic" computing is precisely to permit users and programs to be as effective as possible in this environment of uncertain connectivity, without changes to the manner in which they operate

4. nomadic computing addresses those application and technical issues that arise when persons move around within a region or country, or travel between countries and continents

5. What is not mobile computing
using diverse phones from everywhere in the world is not activity that could be called nomadic computing - because there is no computing (data processing) involved
dragging around a laptop and working with it without being able to set up a connection to the “home base” through a computer network is neither nomadic computing in a strong sense; one must be able to communicate with “home base” and people in other organizations

6. devices to be dragged around by the people
devices to be dragged around by the people? Not necessarily, an infrastructure with suitable access devices could be offered to traveling people - in the same manner as telephones are offered in hotels, airports, etc.; Still, cheap small portable devices like PDAs, laptops, and devices like Nokia Communicator are historically crucial for the idea of nomadic computing
another important development are the advances in computer networking infrastructure that make global connectivity possible
one notable development is the Internet as a global networking infrastructure, but in this context especially the wireless technologies are very important

7. nomadic or mobile computing consists of: traveling people using
portable wireless computing and communication devices connected to
computer network infrastructure supporting global connectivity and remote computing

8. the role of wireless technologies in mobile computing:
wired portable devices can be connected to the network infrastructure only in certain locations for a certain period of time => communication activity of a nomad is spatially and temporally restricted
wireless portable devices, especially those operating with radio transmitter/receiver avoid the above problem to a great extent

9. Mobile computing is characterized by four constraints:
Mobile elements are resource-poor relative to static elements.-weight, size, power
Mobility is inherently hazardous.-security and damage
Mobile connectivity is highly variable in performance and reliability.-outdoor
Mobile elements rely on a finite energy source.

10. Issues in Mobile Computing
Technical Challenges of Mobile Computing
portability,
mobility,
wireless communications
system issues
Which applications can be implemented and used effectively regarding the often narrow bandwidth, limited computing power, small memory and battery capacity and other resources of the terminals?

11. Data Management issues
Wireless Networks
to main types: terrestrial cellular and satellite networks
determine to a large extent application architectures and usable protocols
communication autonomy is an important feature of the terminals in these networks: thus the terminals are not always reachable for variety of reasons
Data Management issues
where to keep the data, when to transmit it, whether to use caching and where in the network, how to optimize data placement, pull/push approach, transactional services, location-dependent queries etc

12. Systems Issues
main goal is to provide a transparent view of the user’s dynamically changing computing and communication environment
key problem is to develop a full system architecture and a set of protocols (i.e. a protocol stack) to support mobile computing; the protocols should support
interoperation between many kinds of infrastructures (e.g. wireline, wireless)

13. maximum independence between the network and the application from both the user’s viewpoint as well as from the development view point
ability to match the nature of what is transmitted to the bandwidth availability (I.e. compression, approximation, partial information, etc)
cooperation among system elements such as sensors, actuators, devices, networks, OS, file system, middleware, services, applications

14. Components that can help in achieving the goals above
an integrated software framework which presents a common virtual network layer
appropriate replication services
file synchronization
predictive caching
consistency services
adaptive database management
location services (to keep track of people and devices)
discovery of resources (where are the suitable services etc)
discovery of profile (where is the profile of a user requesting a networking or computing service)

15. Disciplines which contribute to Mobile Computing:
advanced applications, like multimedia or visualization (a lot of data, high transmission speeds, real time characteristics)
database systems (system service support, application data storage, transactions etc)
file systems (e.g terminal file systems, like Geoworks; network filesystem NFS, iSCSI)
operating systems (e.g. needs of portable terminals like Communicator 9000 and advanced networking operating systems)
network systems ; wireless networks + Internet?

16. Wireless Application Protocol.-ISO layer 2 to Layer 6
Wireless Communications (voice, data, satellites, cellular networks)
Low power, low cost radio technology
Micro-electro-mechanical systems (MEMS) sensor technology, MEMS actuator technology, nanotechnology (e.g. sensored room as an environment to communicate in )