Fundamentals of Mobile
Computing
Dr. Raaid Alubady - Lecture 2
Fundamentals of Mobile Computing
Dr. Raaid Alubady - Lecture 2
1.
Introduction
The rapidly expanding technology of cellular communication, wireless LANs, and
satellite services will make information accessible anywhere and at any time. Mobility is
the most important feature of a wireless cellular communication system. Usually,
continuous service is achieved by supporting handoff (or handover) from one cell to
another. Handoff is the process of changing the channel (frequency, time slot, spreading
code, or combination of them) associated with the current connection while a call is in
progress. It is often initiated either by crossing a cell boundary or by a deterioration in
quality of the signal in the current channel.
Mobile phones have been popular; powerful smartphones are now a regular choice for
consumers. Today, the mobile phone technology is mature enough to enable us to
effectively interact with mobile phones using our three major senses namely, vision,
hearing and touch. Similar to the camera, which adds interest and utility to mobile
experience, the vibration motor in a mobile phone could give us a new possibility to
improve interactivity and usability of mobile phones.
2.
Mobile Computing
Mobile computing is the discipline for creating an information management platform,
which is free from spatial and temporal constraints. The freedom from these constraints
allows its users to access and process desired information from anywhere in the space. The
state of the user, static or mobile, does not affect the information management capability
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Fundamentals of Mobile
Computing
Dr. Raaid Alubady - Lecture 2
of the mobile platform. A user can continue to access and manipulate desired data while
traveling on plane, in car, on ship, etc. Thus, the discipline creates an illusion that the
desired data and sufficient processing power are available on the spot, whereas in reality
they may be located far away. The discipline of mobile computing has its origin in Personal
Communications Services (PCS). PCS refers to a wide variety of wireless access and
personal mobility services provided through a small terminal (e.g., cell phone), with the
goal of enabling communications at any time, at any place, and in any form. PCS are
connected to Public Switched Telephone Network (PSTN) to provide access to wired
telephones. PCS include high-tier digital cellular systems for widespread vehicular and
pedestrian services and low-tier telecommunication system standards for residential,
business, and public cordless access applications.
2.1. Principles of Mobile Computing
 Portability: Devices/nodes connected within the mobile computing system should
facilitate mobility. These devices may have limited device capabilities and limited
power supply, but should have a sufficient processing capability and physical
portability to operate in a movable environment.
 Connectivity: This defines the Quality of Service (QoS) of the network
connectivity. In a mobile computing system, the network availability is expected to
be maintained at a high level with the minimal amount of lag/downtime without
being affected by the mobility of the connected nodes.
 Interactivity: The nodes belonging to a mobile computing system are connected
with one another to communicate and collaborate through active transactions of
data.
 Individuality: A portable device or a mobile node connected to a mobile network
often denote an individual; a mobile computing system should be able to adopt the
technology to cater the individual needs and also to obtain contextual information
of each node.
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Fundamentals of Mobile
Computing
Dr. Raaid Alubady - Lecture 2
2.2. Mobile Computing Application Issues
The programs 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: First come the Technical Design Issues, which 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 and offers unique challenges to the
system professionals.
 Network Design: Issues regarding Wireless LAN design and Wide Area Radio
Network Design which network design comprises are discussed below.
 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.
•
Use of notebook computer with a wireless NIC as a primary and user
device.
•
Roaming areas, location and range of needed access point.
•
Impact of construction materials in single penetration.
•
Preferred technology-spread spectrum or frequency hopping.
•
Radio frequency interference from any other devices in office, factory or
campus etc.
 Wide Area Radio Network Design Issues
•
The need of building a private radio network.
•
Most appropriate radio network technology for the suite of applications.
•
Matching of user application-usage profiles to a given network capacity.
•
Integration of RNA technology with a radio network infrastructure.
•
Ensuring good coverage and minimum number of dead spots.
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Fundamentals of Mobile
Computing
Dr. Raaid Alubady - Lecture 2
•
If distributed wireless network design with several MCSSs must be used?
•
Managing the way logic networks will be influenced by network design
options.
 The Capacity Planning and Response Time: A mobile computing application
transaction has to cover a synchronous set of hardware as well as software
components before it reaches the destination server. Diverse physical links, wireless
and wired line in between the end user's client application software and the
information server are present in its reverse path too. So scheduling on a network
requires complex rules, which makes it difficult to build a mathematical model to
estimate response times. Planning reliable capacities in advance is a hard task still.
The network providers give an estimate using complex queuing models or rule-of
thumb calculation based on the other customer's experience.
 Data Compression Considerations: As the bandwidth of wireless network is scarce
and expensive it is necessary to compress data to get the maximum out of this
bandwidth. This is usually done in the modem by going beyond the modem
hardware in reducing the quantity of traffic on wireless networks using client
application programs.
 System Availability Design: Rather than sticking on with the general base station
hardware and network controllers, redundancy and message switches are typically
built on fault-tolerant platforms. Public shared network providers must be
approached for details of their redundancies.
 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-their encryption & firewalls
must be used.
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Fundamentals of Mobile
Computing
Dr. Raaid Alubady - Lecture 2
3.
Mobile Network
A mobile network (Cellular networks) is a communication network where the last link
is wireless. The network is distributed over land areas called cells, each served by at least
one fixed-location transceiver, but more normally three cell sites or base transceiver
stations. These base stations provide the cell with the network coverage which can be used
for transmission of voice, data and others. A cell typically uses a different set of
frequencies from neighboring cells, to avoid interference and provide guaranteed service
quality within each cell. When joined together these cells provide radio coverage over a
wide geographic area. This enables a large number of portable transceivers (e.g., mobile
phones, tablets and laptops equipped with mobile broadband modems, pagers, etc.) to
communicate with each other and with fixed transceivers and telephones anywhere in the
network, via base stations, even if some of the transceivers are moving through more than
one cell during transmission.
Cellular networks offer a number of desirable features:
•
More capacity than a single large transmitter, since the same frequency can be used
for multiple links as long as they are in different cells
•
Mobile devices use less power than with a single transmitter or satellite since the
cell towers are closer
•
Larger coverage area than a single terrestrial transmitter, since additional cell towers
can be added indefinitely and are not limited by the horizon.
4.
Mobile Computing Devices
A mobile computing device is any device that is created using mobile components, such
as mobile hardware and software. Mobile computing devices are portable devices capable
of operating, executing and providing services and applications like a typical computing
device. Mobile computing devices also may be known as portable computing devices or
handheld computing devices. Some of the most common forms of mobile computing
devices are:
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Fundamentals of Mobile
Computing
Dr. Raaid Alubady - Lecture 2
Netbooks
A netbook is a small, light, low-power notebook computer that has less processing power
than a full-sized laptop but is still suitable for word processing, running a Web browser
and connecting wirelessly to the Internet. Netbooks fall into a category of what vendors
refer to as “small form” computers. Such computers have been known by various names,
including subnotebook, ultra-portable, mini-notebook, mini-thin client, cloudbook and
ultra-mobile PC. Typically, a netbook will have a slimmed-down operating system, a
smaller-than-usual keyboard, a smaller-than-usual screen and very little (if any) storage
space.
Cellular phone
In this networked system, the cellular phone is identified as a mobile system consisting of
the equipment and SIM card that actually assigns the mobile telephone number. A cell
phone is a portable telephone that can make and receive calls over a radio frequency link
while the user is moving within a telephone service area. The radio frequency link
establishes a connection to the switching systems of a mobile phone operator, which
provides access to the Public Switched Telephone Network (PSTN). Modern mobile
telephone services use a cellular network architecture, and, therefore, mobile telephones
are called cellular telephones or cell phones.
Smart phone
A smartphone is a handheld personal computer with a mobile operating system and an
integrated mobile broadband cellular network connection for voice, SMS, and Internet data
communication; most if not all smartphones also support Wi-Fi. Smartphones are typically
pocket-sized, as opposed to tablets, which are much larger. They are able to run a variety
of software components, known as “apps”. Most basic apps (e.g. event calendar, camera,
web browser) come pre-installed with the system, while others are available for download
from places like the Google Play Store or Apple App Store.
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Fundamentals of Mobile
Computing
Dr. Raaid Alubady - Lecture 2
Smart pad
Smart pad (multi-finger touch pad) is a different from traditional touchpad, because it can
support multi-finger gesture to let user interact with their notebook system more intuitively.
5.
Limitations of Mobile Computing
 Range and bandwidth: Mobile Internet access is generally slower than direct cable
connections, using technologies such as GPRS and EDGE, and more recently 3G
and 4G networks and also the proposed 5G network. These networks are usually
available within range of commercial cell phone towers. High speed network
wireless LANs are inexpensive but have very limited range.
 Security standards: When working mobile, one is dependent on public networks,
requiring careful use of VPN. Security is a major concern while concerning the
mobile computing standards on the fleet. One can easily attack the VPN through a
huge number of networks interconnected through the line.
 Power consumption: When a power outlet or portable generator is not available,
mobile computers must rely entirely on battery power. Combined with the compact
size of many mobile devices, this often means unusually expensive batteries must
be used to obtain the necessary battery life.
 Transmission interferences: Weather, terrain, and the range from the nearest signal
point can all interfere with signal reception. Reception in tunnels, some buildings,
and rural areas is often poor.
 Potential health hazards: People who use mobile devices while driving are often
distracted from driving and are thus assumed more likely to be involved in traffic
accidents. Cell phones may interfere with sensitive medical devices. Questions
concerning mobile phone radiation and health have been raised.
 Human interface with device: Screens and keyboards tend to be small, which may
make them hard to use. Alternate input methods such as speech or handwriting
recognition require training.
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