1.
Mobile computing
Assignment 1
Name :Abir Biswas
College Rollno :CSE/19/114
University Rollno :10700119013
Subject : Mobile computing
Subject Code : PEC-CS702E

2.
OBJECTIVES
The Overview of GSM Architecture has a brief explanation of the
different networks subsystems and description of the functionality of
the elements within each of the subsystems.The evaluation and
generation of GSM explained
GSM
Global System For Mobile(GSM) is a second generation cellular standard
developed to cater voice services and data delivery using digital
modulation GSM digitizes and compresses data,then sends it don a
channel with two other streams of user data ,each in its own time slot.It
operates at either the 900 megahertz(MHZ)or 1800 MHZ frequency band
GSMHISTORY
Developed by group speciale mobile(founded 1892) which was an
initiative of CPET(Conference of European Post and Telecommunication)
Under ETSI,GSM is named as ”Global System for Mobile Communication”

3.
The EvolutionOf GSM
1G -Voice Signals only
-Analogue cellular phones
-NMT,AMPS
2G -Voice and data signals
-Digital Fidelity Cellular phones
-GSM,CDMA,TDMA
3G -Voice,Data and videos signals
-Video Telephony/Internet Surfing
-3G,W-CDMA,UMTS
4G -Enhanced 3G/Interoperability Protocal
-High speed and IP-based
-4G,mobile IP

4.
Result and Discussion
The mobile telephony industry growing and that has become backbone for
business success and efficiency and a part of modem lifestyles all over the
world
In this session I have tried to give and over view of the GSM system. I hope
that I gave the general flavor of GSM and the philosophy behind its design
Cellular mobile radio-the high end sophisticated technology that enables
every one to communicate anywhere with anybody.
The GSM is standard that insures interoperability without stifling
competition and innovation among the suppliers to the benefits of thr
public both in terms of cost and services quality
The features and benefits expected in the GSM systems are superior
speech quality,Low terminal,Operational and service costs,High level
security,providing international roaming support of low power hand

5.
What is GPRS ?
General Packet Radio Service (GPRS) is a new bearer service for GSM that
greatly improves and simplifies wireless access to packet data networks.
GPRS applies packet radio principal to transfer user data packets in an
efficient way b/w MS & external packet data network
Salient Features of GPRS
• Important step on the path to 3G
• Standardized by ETSI• GPRS is an overlay network over the GSM
• Provides Data Packet delivery service
• Support for leading internet communication protocolsBilling based on volume of
data transferred
• Utilizes existing GSM authentication and privacy procedures
Applications of GPRS
• Corporate & Internet Email
• Vehicle Positioning

6.
Conclusion
In this tutorial, we have taught you all the basic concepts
related to GPRS technology. Hope, now you have basic
understanding of GPRS Technology.
You have learnt about GPRS basic overview, its architecture, a
short description of GSM protocol stack and available GPRS
applications. We also told you how you can charge GPRS
services.
A list of all the important GPRS Acronyms has been given for
your quick reference. So you can book mark this page for future
reference.
GPRS provides efficient access to Packet Data
Networks.Multislot operation in GPRS leads to efficient channel

7.
Introductionto CDMA
CDMA - Code Division Multiple Access
• Fully digital wireless data transmission system
• Uses special random numbers to encode bits of information.
• Allows multiple access by assigning different users different random numbers on
the same channel.
• Users have control of a very wide channel bandwidth 1.5 to 5 MHz
• Built-in interference minimization.
Background
1993, the first CDMA standard IS-95 was issued;
In 1995, CDMA technology was put into commercialization in Hong Kong and
America on large scale.
In April, 2001, China Unicom began to construct CDMA networks-the largest in the
world (about 70Million line now).
At present, CDMA commercial networks are established in about 40 countries or
area, almost 20% of all users in the world.

8.
Advantages of CDMA
• CDMA consumes less power and covers large areas so cell size in CDMA is larger.
• CDMA is able to produce a reasonable call with lower signal (cell phone reception)
levels.
• CDMA uses Soft Handoff, reducing the likelihood of dropped calls.
• Has a well-defined path to higher data rates.
Disadvantages of CDMA
• Most technologies are patented and must be licensed from Qualcomm.
• Breathing of base stations, where coverage area shrinks under load. As the number
of subscribers using a particular site goes up, the range of that site goes down.
• Currently CDMA covers a smaller portion of the world as compared to GSM which
has more subscribers and is in more countries overall worldwide.
Conclusion
• The CDMA will allow many signals to be transmitted at the same channel at the
same time. This done by giving each user a Pseudo- Noise code which is a binary
sequence. This code should have low cross-correlation between each other.Multiple

9.
What is a WLAN
• A wireless local area network (LAN) is a flexible data communications system
implemented as an extension to,
or as an alternative for, a wired LAN.
Using radio frequency (RF) technology, wireless LANS transmit and receive data over
the air, minimizing the need for wired connections.Thus, combining data connectivity
with user mobility.
Benefits of WLAN
Productivity, convenience, and cost advantages
- Installation speed and simplicity.
- Installation flexibility.
- Reduced cost-of-ownership.
- Mobility.
Disadvantage of WLAN
• Cost
- Wireless network cards cost 4 times more than wired network cards.
- The access points are more expensive than hubs and wires.
- Access points pick up the signals of adjacent - access points or overpower their

10.
Conclusion
• Wi-Fi is a simple, cost-effective way to connect to the Internet, without the
need to physically connecting wires.
In 1997 IEEE drafted the 802.11 standard for wireless local area networking.
Hotspot is a geographic area setup in any public location, and has a readily
accessible wireless network.
Security is a huge challenge for Wi-Fi Networks, many Security Techniques are
used to improve it.
Wi-Fi Networks have a several limitations that should be concerned.

11.
What is Global Mobile Satellite System
GMSS stands for Global Mobile Satellite System. An artificial body
which is placed in an orbit around the earth for the purpose of
communication is known as Communication satellite. GMSS is a
system which consists of various artificial communication satellites
orbiting around the earth for the purpose of communication.
A satellite network is a combination of nodes that provides
communication from one point on the Earth to another. A node in
the network can be Satellite, an Earth station, or an End-user
terminal or Telephone. Satellite networks are like cellular
networks, they divide the planet into cells.
The frequencies reserved for the satellite microwave
communication are in gigahertz(GHz) range. Each satellite sends
and receives over two different bands. Transmission from earth to
satellite is called the Uplink. Transmission from the satellite to the

12.
Advantages :
• Through satellite transmission, coverage over geographical area is quite large
mainly for sparsely populated
• High bandwidth and broadcast possibilities .
• Wireless and mobile communication applications can be easily established by
satellite communication
• Ground station sites are easy to install and maintain.
• Point to multipoint communication is possible.
• Satellite cost is independent of the distance.
Disadvantages :
• Design, development, investment, and insurance of satellite requires higher cost.
• There can be a congestion of frequencies.
• propagation issues and interference may arise.
• Launching satellites into orbit is an expansive process
• Due to aging effect the efficiency of satellite components decreases.
• Free space loss is more.

13.
Conclusion
The background study of mobile satellite communication was given
in this thesis and the various types of satellites available with their
advantages and disadvantages. The basic propagation mechanisms,
various channel impairments and types of fading were discussed as
well. There were major statistical models developed to represent a
mobile satellite channel as cited in the references. However, a
statistical model developed by Lutz was selected and its
performance was evaluated by simulations. Lutz model is a two-
state model which reasonably represent most known fading
conditions; it combines the three basic probability distributions –
Rayleigh, Rician and lognormal in good proportions to describe the
fading channel. This model has compared reasonably well when
simulated with the analytica result.

14.
THANK YOU