Mobile
Computing and Networks
Mobile computing can be
defined as a computing environment over physical mobility. The user of a mobile computing environment
will be able to access data, information or other logical objects from any
device in any network while on the move.
Mobile computing system allows a user to perform a task from anywhere
using a computing device in the public (the Web), corporate (business
information) and personal information spaces (medical record, address book).
While
on the move, the preferred device will be a mobile device, while back at home
or in the office the device could be a desktop computer. To make the mobile computing environment
ubiquitous, it is necessary that the communication bearer is spread over both
wired and wireless media.
In
mobile computing, computing environment is mobile and it moves along with the
user. We can define a computing
environment as mobile if it supports one or more of the following
characteristics:
User
Mobility: User should
be able to move from one physical location to another location and use the same
service. Example could be a user moves
from London to New York and uses Internet to access the corporate application
the same way the user uses in the home office.
Network
Mobility: User should
be able to move from one network to another network and use the same
service. Example could be a user moves
from Hong Kong to New Delhi and uses the same GSM phone to access the corporate
application through WAP (Wireless Application Protocol). In home network he uses this service over
GPRS (General Packet Radio Service) whereas in Delhi he accesses it over the
GSM network.
Bearer
Mobility: User should
be able to move from one bearer to another and use the same service. Example could be a user using a service
through WAP bearer in his home network in Bangalore, moves to Coimbatore, where
WAP is not supported. He can switch over
to voice or SMS (Short Message Service) bearer to access the same application.
Device
Mobility: User should
be able to move from one device to another and use the same service. Example could be sales representatives using
their desktop computer in home office.
During the day while they are on the street they would like to use their
Palmtop to access the same application.
The device for mobile
computing can be either a computing device or a communication device. In computing device category it can be a
desktop computer, laptop computer, or a palmtop computer. On the communication device side, it can be
fixed line telephone, a mobile telephone or a digital T.V. Usage of these devices are becoming more and
more integrated to task flow where fixed and mobile, computing and
communication devices are used together.
Use
of Networks in Mobile Computing:
Mobile
computing uses different types of networks.
They are listed below:
- Fixed telephone network
- GSM
- GPRS
- ATM (Asynchronous Transfer Mode) Network
- Frame Relay Network
- ISDN (Integrated Service Digital Network)
- CDMA
- CDPD (Cellular Digital Packet Data) Network
- DSL (Digital Subscriber Loop) Network
- Dial-up Network
- WiFi (Wireless Fidelity) Network
- 802.11 (Wireless LAN)
- Bluetooth Network
- Ethernet (Wired network)
- Broadband Network etc.
Wireline
Network:
This
is a network, which is designed over wire or tangible conductors. This network is called fixed or wireline
network. Fixed telephone networks over
copper and fiber-optic will be part of this network family. Broadband networks over DSL or cable will also
be part of wireline networks.
Wireline
networks are generally public networks and cover wide areas. Though microwave or satellite networks do not
use wire, when a telephone network uses microwave or satellite as a part of
infrastructure, it is considered part of wireline networks. When we connect to ISPs it is generally a wireline
network. The Internet backbone is a
wireline network as well.
Wireless
Network:
Mobile
networks are generally termed as wireless network. This includes wireless networks used by radio
taxis, one way and two way pager, cellular phones. Example will be PCS (Personal Cellular
System), AMPS (Advanced Mobile Phone System), GSM, CDMA, DoCoMo, GPRS etc.
WiLL
(Wireless in Local Loop) networks using different types of technologies are
part of wireless networks as well. In a
wireless network the last mile is wireless and works over radio interface. In a wireless network other than the radio
interface rest of the network is wireline, this is generally called the PLMN
(Public Land Mobile Network).
Ad-hoc
Network:
In
Latin, ad hoc literally means ‘for
this purpose only’. An ad-hoc (or
spontaneous) network is a small area network, especially one with wireless or
temporary plug-in connections. In these
networks, some of the devices are part of the network only for the duration of
a communication session. An ad-hoc
network is also formed when mobile, or portable devices, operate in close
proximity of each other or with the rest of the network.
The term ‘ad hoc’ has
been applied to networks in which new devices can be quickly added using, for
example, Bluetooth or Wireless LAN (802.11x).
In these networks, devices communicate with the computer and other
devices using wireless transmission.
Typically based on short-range wireless technology, these networks don’t
require subscription services or carrier networks.
Bearers:
For different type of
networks, there are different types of transport bearers. These can be TCP/IP, http, protocols for
dialup connection. For GSM, it could be
SMS, USSD (Unstructured Supplementary Service Data) or WAP. For mobile or fixed phone, it will be voice.
