Mobile computing allows users to access network services and complete work processes from any location using a wireless device. It provides various benefits like flexibility, mobility, and scalability but also faces limitations such as insufficient bandwidth, security risks, and device constraints. GSM is a cellular network standard that defines protocols for second-generation digital cellular networks. It enables wireless voice and data communication through technologies like GPRS that allow packet-based data transmission.

1. Introduction of Mobile Computing

2. Definition on Mobile
Computing!
A simple definition could be:
Mobile Computing is using a computer (of one kind or another)
while on the move
Another definition could be:
Mobile Computing is when a (work) process is moved from a
normal fixed position to a more dynamic position.
A third definition could be:
Mobile Computing is when a work process is carried out
somewhere where it was not previously possible.

3. What is Mobile Computing?
 Mobile Computing is a technology that allows
transmission of data, voice and video via a
computer or any other wireless enabled device
without having to be connected to a fixed
physical link.
 Mobile Computing is an umbrella term used to
describe technologies that enable people to
access network services anyplace, anytime, and
anywhere.

4. Mobility
A device that moves
 Between different geographical locations
 Between different networks
 Between different applications
 Such as Palm-top, laptop,
 Cell phones
A device due to which mobile communication
is possible
 Modems.

5. Types of mobility
• user mobility: users communicate
anytime, anywhere, with anyone
• device portability: devices can be
connected anytime, anywhere to the
network

6. Wireless Communication
Wireless refers to the method of transferring
information between a computing device, such
as a personal data assistant (PDA), and a data
source, such as an agency database server,
without a physical connection. Not all wireless
communications technologies are mobile.
For example, lasers are used in wireless data
transfer between buildings, but cannot be used
in mobile communications at this time.

7. • The wire is replaced by electro magnetic spectrum
wave
• Data transmission through the air

8. Characteristics of communication devices
1. Fixed & wired: desktop
2. Mobile & wired :laptops connected with any fixed
network
3. Fixed &wireless :wi-fi
4. Mobile & wireless: Mobile phones

9. Why Mobile Computing?
•Enable anywhere/anytime connectivity
•Bring computer communications to areas without pre
existing infrastructure
•Enable mobility
•Enable new applications
•An exciting new research area

10. Computer Network
A computer network is collection of several
homogeneous/heterogeneous system, commonly used for
resource sharing.
Computer networks can be classified in many ways:
Area wise:
- LAN , MAN & WAN
As per medium used:
- Wired Computer Network & Wireless Computer Network

11. Wired Vs. Wireless Networks
Wired Networks
- high bandwidth
- can listen on wire
- high power machines
- high resource machines
- need physical
access(security)
- low delay
Mobile Networks
- low bandwidth
- hidden terminal problem
- low power machines
- low resource machines
- need proximity
- higher delay

12. Advantages of Wireless Networks
Flexible: Radio waves can penetrate the obstacles. Sender and
receiver can be placed any where.
Mobility: Data can be access from any location.
Robustness : Can survive in disaster (Earthquake, military
operations)
Scalable: Can be configured in variety of topologies.
Easy Installation
Less Cost
Usage of ISM band: ISM (Industrial, Scientific and Medical) band
(2.40GHz to 2.484 GHz, 5.725 GHz to 5.850 GHz) is available for
use by anyone.
No Planning: Only Wireless Ad hoc not required any planning.

13. Disadvantages of Wireless Networks
Quality of Service:
Lower Bandwidth
Lower Data Transmission Rate
High Error Rates
Interference
Higher Delay
Restrictions: License-free frequency bands are not same worldwide.
Safety and Security: Interference from other devices

14. Types of Wireless Devices
Laptops
Palmtops
PDAs
Cell phones
Pagers
Sensors

15. Sensor:
• A very simple wireless device is represented
by a sensor transmitting state information.
Embedded controllers:
• Many appliances already contain a simple
or sometimes more complex controller
Pager:
• pager can only display short text messages,
• has a tiny display, and cannot send any
messages. Pagers can even be integrated
into watches.

16.  Mobile phones:
• The traditional mobile phone only had a simple
black and white text display and could
send/receive voice or short messages.
• Today, mobile phones migrate more and more
toward PDAs. Mobile phones with full color
graphic display, touch screen, and Internet
browser are easily available.
 Personal digital assistant:
• PDAs typically accompany a user and offer
simple versions of office software
• The typical input device is a pen, with built-in
character recognition translating handwriting into
characters.

17. Pocket computer:
• pocket computers offering tiny keyboards,
color displays, and simple versions of
programs found on desktop computers
Notebook/laptop:
• Finally, laptops offer more or less the
same performance
• as standard desktop computers; they use
the same software – the only technical
difference being size, weight, and the ability
to run on a battery. If operated mainly via a
sensitive display

19. Applications
 Vehicles
 transmission of news, road conditions,
weather
 personal communication using cellular
phones
 position identification via GPS
 inter vehicle communications for accident
prevention
 vehicle and road inter communications for
traffic control, signaling, data gathering
 ambulances, police, etc.: early
transmission of patient data to the hospital,

21.  Mobile workers
 access to customer files and company documents
stored in a central location
 collaborative work environments
 access to email and voice messages
 Replacement of fixed networks
 remote sensors, e.g., weather, environment, road
conditions
 flexible work spaces
 LANs in legacy buildings
 Entertainment, education, ...
 outdoor Internet access
 intelligent travel guide with up-to-date
 location dependent information
 ad-hoc networks for multi user games

22. •For Estate Agents:
Estate agents can work either at home or out in the field.
With mobile computers they can be more productive.
They can obtain current real estate information by
accessing multiple listing services, which they can do
from home, office or car when out with clients.
•Emergency Services: Ability to receive information on
the move is vital where the emergency services are
involved. Information regarding the address, type and
other details of an incident can be dispatched quickly,
•Credit Card Verification: At Point of Sale (POS)
terminals in shops and supermarkets, when customers
use credit cards for transactions, the intercommunication
is required between the bank central computer and the
POS terminal, in order to effect verification of the card
usage, can take place quickly and securely over cellular

23. Impact of Portability on Device
Design/Functionality
 Power consumption
 battery capacity - limited computing power, low quality/smaller displays,
smaller disks, fewer options (I/O, CD/DVD)
 CPU: power consumption ~ CV2f
 C: internal capacity, reduced by integration
 V: supply voltage, can be reduced to a certain limit
 f: clock frequency, can be reduced dynamically based on usage
 Device vulnerability
 more rugged design required to withstand bumps, weather conditions, etc.
 theft
 Limited/Simpler User Interfaces
 display size
 compromise between comfort/usability and portability (keyboard size)
 integration of character/voice recognition, abstract symbols
 Limited memory
 memory limited by size and power
 flash-memory or ? as alternative

24. Wireless Networks Compared to
Fixed Networks
 Higher loss-rates due to interference
 other EM signals, objects in path (multi-path, scattering)
 Limited availability of useful spectrum
 frequencies have to be coordinated, useful frequencies
are almost all occupied
 Low transmission rates
 local area: 2 – 11 Mbit/s, wide area: 9.6 – 19.2 kbit/s
 Higher delays, higher jitter
 connection setup time for cellular in the second range,
several hundred milliseconds for wireless LAN systems
 Lower security, simpler active attacking
 radio interface accessible for everyone
 base station can be simulated, thus attracting calls from
mobile phones
 Always shared medium
 secure access mechanisms important

25. Limitations of Mobile Computing
1.Insufficient Bandwidth: Mobile Internet access is
generally slower than direct cable connections, using
technologies such as GPRS and EDGE, and more
recently 3G networks. These networks are usually
available within range of commercial cell phone
towers. Higher speed wireless LANs are inexpensive
but have very limited range.
2. Security Standards: When working mobile, one is
dependent on public networks, requiring careful use of
Virtual Private Network (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.
3. Power consumption: When a power outlet or portable
generator is not available, mobile computers must rely

26. 4. 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.
5. Potential health hazards: People who use mobile
devices while driving are often distracted from driving are
thus assumed more likely to be involved in traffic
accidents. Cell phones may interfere with sensitive
medical devices. There are allegations that cell phone
signals may cause health problems.
6. 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.

27. GSM

31. Introduction
 GSM stands for Global System for Mobiles.
 GSM is a cellular network, which means that cell phones connect to
it by searching for cells in the immediate vicinity.
 This is a world-wide standard for digital cellular telephony
 GSM was created by the Europeans, and originally meant "Groupe
Special Mobile“
 to describe the protocols for second-generation digital cellular
networks used by mobile devices such as tablets,
 first deployed in Finland in December 1991
 As of 2014, it has become the global standard for mobile
communications – with over 90% market share, operating in over
219 countries and territories
 2G networks developed as a replacement for first generation
analog cellular networks, and the GSM standard originally
described as a digital, circuit-switched network optimized for full
duplex voice telephony.

32. In 2001 the first commercial launch of 3G was done in
Japan. With 3G following services are available :
Video Conferencing
online games
net surfing..

34. • Communication
mobile, wireless communication, support for voice and data
services
• Total mobility
international access, chip-card enables use of access points of
different providers.
• Worldwide connectivity
one number, the network handles every location.
• High capacity
better frequency efficiency, smaller cells, more customers per
cell.
• High transmission quality
high audio quality and reliability for wireless, uninterrupted
phone calls at higher speeds (e.g., from cars, trains).
Advantages

40. Supplementary services

41. Bearer services

42. Data rate for Bearer services

43. GSM Architecture

44. GSM Architecture

48. Radio subsystem

52. Functions of BTS

55. Network subsystem

83. GMSC Identified

102. Mobile originating call

103. Call connection process

111. Radio interface

113. List of interfaces in GSM
Interfac
e
Description
Um MS↔ BTS
ABis BTS↔ BSC
A BSC ↔ (G)MSC
B (G)MSC↔ VLR
C (G)MSC↔ HLR
D VLR↔HLR
E (G)MSC↔ (G)MSC
F (G)MSC↔ EIR
G VLR↔ VLR
H HLR ↔AUC

117. Handover
Purpose
1.To keep continuous communication with
moving MS
2.To improve network performance
3.To reduce the call drop rate
4.To reduce the congestion rate

118. Types of GSM handover
1.Intra-BTS handover:
Because of interference, or other reasons
2. Inter-BTS Intra BSC handover:
The mobile moves out of the coverage area of one BTS
3. Inter-BSC handover:
When the mobile moves out of the range of cells controlled by
one BSC
4. Inter-MSC handover:
when changing between networks

120. Security in GSM
 Security services
 access control/authentication
 user  SIM (Subscriber Identity Module): secret PIN (personal
identification number)
 SIM  network: challenge response method
 confidentiality
 voice and signaling encrypted on the wireless link (after
successful authentication)
 anonymity
 temporary identity TMSI
(Temporary Mobile Subscriber Identity)
 newly assigned at each new location update (LUP)
 encrypted transmission
 3 algorithms specified in GSM
 A3 for authentication (“secret”, open interface)
 A5 for encryption (standardized)
 A8 for key generation (“secret”, open interface)
“secret”:
• A3 and A8
available via the
Internet
• network providers
can use stronger
mechanisms

121. security concerns can be defined in two
side; operator side and customer side.
Operators:
 Should bill the right person
 Should provide systems to avoid fraud
 Should protect their services against attacks
Customers
 Should have privacy, nobody should be able to detect
their identification or their location
 Communication on the air should be encrypted to
avoid eavesdropping
 Should be able to change mobile equipment
independently

122. Security mechanisms
 Shouldn’t add much load to the voice calls or
data communication
 Shouldn’t need to increase the channel
bandwidth
 Shouldn’t increase the bit error rate
 Shouldn’t bring expensive complexity to the
system
 Should be useful and cost efficient
 Should be able to detect suspicious mobile
equipment

123. GSM security can be written in 4
principles
 Authentication of a user it provides the ability for mobile
equipment to prove that it has access to a particular
account with the operator.
 Ciphering of the data and signaling it requires that all
signaling and user data (such as text messages and
speech) are protected against interception by means of
ciphering
 Confidentiality of a user identity it provides IMSI’s security.
GSM communication uses IMSI rarely, it uses TMSI
(Temporary Mobile Subscriber Identity) to provide more
secure communication and to avoid disclosing of user’s
identity
 Using SIM as security module Incase SIM card was taken
by opponent, there is still PIN code measurement.

130. GSM Protocol stack

131. •GSM Data services are the processes that can transfer digital
information between wireless devices and the GSM system.
•GSM data services use
o a continuous connection - circuit switched data
oA bursty data transmission - packet switched data.
•Circuit Switched Data - GSM circuit switched data is the
reserving of a continuous path of transmission resources from
a sender to a receiver.
•GSM data may dedicate a variable number of transmission
time slots per frame for circuit switched data connection.
•For circuit switched connections, the data transmission path is
always available even if there is no data to send.
GSM Data services

132. •Packet Switched Data - GSM packet switched data is the
sending of data which is divided into small packets which can
take different paths through a packet data network.
•The GSM radio channel was modified in the GPRS system to
allow the dynamic assignment of time slots to enable packet
data to be sent on the GSM radio channel.
•Fax Services - Fax service is the transmission of facsimile
(image) information between users.
•Facsimile signals are normally sent using audio frequencies
which cannot be sent through the GSM voice coder.
• To send fax signals through the GSM system, the GSM
system must decode the fax signal and send it in digital form.
•When the fax data reaches its GSM exit point, the GSM
system must reconvert the digital fax back into it original analog
form

133. •It is a packet-based wireless communication service that
promises data rates from 56 up to 114 Kbps and continuous
connection to the Internet for mobile phone and computer
users.
•The higher data rates allow users to take part in video
conferences and interact with multimedia Web sites and
similar applications using mobile handheld devices as well
as notebook computers.
• GPRS is based on Global System for Mobile (GSM)
communication and complements existing services
such circuit-switched cellular phone connections and the
Short Message Service (SMS).
General Packet Radio Services (GPRS)

134. •GPRS packet-based services cost users less than circuit-
switched services since communication channels are being
used on a shared-use, as-packets-are-needed basis rather
than dedicated to only one user at a time.
• It is also easier to make applications available to mobile users
because the faster data rate

135. Enabling GPRS on a GSM network requires the addition of
two core modules,
- the Gateway GPRS Service Node (GGSN)
- GGSN acts as a gateway between the GPRS network and
Public Data Networks such as IP and X.25.
- GGSNs also connect to other GPRS networks to facilitate
GPRS roaming.
- the Serving GPRS Service Node (SGSN).
- provides packet routing to and from the SGSN
service area for all users in that service area.

136. GPRS network elements
GSN (GPRS Support Nodes): GGSN and SGSN
 GGSN (Gateway GSN)
interworking unit between GPRS and PDN
(Packet Data Network)
SGSN (Serving GSN)
supports the MS (location, billing, security)
 GR (GPRS Register)

137. GPRS Advantages
IMMEDIACY
INTERNET AWARE
SPEED
No Dial Up