Wireless and
Mobile
Communications
Course Instructor:
Dr. Rabia Noor Enam
Text Book: Wireless
Communications and Networks
by William Stallings, Second
Edition
Reference Book: Wireless
Communications: Principles And
Practice, by Rappaport Theodore
S., Second Edition.
Course Outline
Week No.
Topic
Introduction to Wireless Network Technology, History and Types of
wireless networks, Basic wireless network architectures
2
3
4
5
6
Cellular Wireless Networks
10
Wireless LAN Technologies
13
Wi-Fi and IEEE 802.11 Wireless LAN standards
14
7
8
9
10
11
12
13
14
15
16
Bluetooth and IEEE 802.15 Standards
Satellite Communications
MID TERM
Spread Spectrum
15
9
Antennas & Propagations
Mobile IP
12
Revision & Final Quiz
Chapter No.
Week Wise Lab Outline
Week
No
1
Contents
4
5
6
Introduction to Wireless Network and its technologies
Configure the Cisco LINKSYS Wireless-G Broadband Router for Wireless
Infrastructure Mode
Configure the Cisco LINKSYS Wireless-G Broadband Router for Wireless Ad-hoc
Mode
Interconnecting Wired LAN with Wireless LAN
Configure LINKSYS Broadband Router as DHCP server
Authentication Methods, Wireless Equivalent Privacy (WEP)
Revision
Pre-Mid Viva
MID TERM
10
11
12
13
14
15
MAC Address Filtering
IP Filtering
Configuring Access Point as a Wireless Client of a Wireless Broadband Router
NAT/PAT Support by the Wireless Broadband Router
Configure Voice over IP (VoIP)
Configure Syslog and NTP
2
3
Page No in
manual
01-08
09-15
16-19
20-22
23-27
28-35
36-41
42-46
47-52
53-61
62-66
67-69
Wireless network
The
term Wireless Networks refers to any kind of networking
that does not involve cables.
It
is a technique that helps to save the cost of cables for networking in
specific premises in their installations.
But
the major advantage of wireless networks is the mobility and
roaming of its users
The
transmission system is usually implemented and administrated
via radio waves where the implementation takes place at physical
level.
Wireless History
Ancient
Systems: Smoke Signals,
Radio
Carrierinvented
Pigeons,inthe 1880s by
Marconi
Many sophisticated military radio
systems were developed during and
after WW2
Cellular has enjoyed exponential
growth since 1988, with almost 5
billion users worldwide today
Ignited
the wireless revolution
Voice, data, and multimedia ubiquitous
Use in third world countries growing
Wifi
also enjoying tremendous success
rapidly
and growth
Wide
area networks (e.g. Wimax) and
Communication
History
AMPS: Advance mobile phone System
Developed by Bell Labs,
Officially introduced in Pakistan in 1990. discontinued by October 2004.
NMT: Nordic Mobile Telephone
Basic difference number of channels and frequency bands
Both use FDD and FDMA
GSM: Global System for Mobile Communications
D-AMPS: Digital-AMPS
Both use TDMA
IS-95: Interim Standard
Uses CDMA
UMTS: Universal Mobile Telecommunications System
Advanced GSM moved to W-CDMA Also Called UMTS
UMTS supports maximum theoretical data transfer rates of 42 Mbits/s
Advanced IS-95 moved to CDMA 2000
TD-SCDMA: Time Division Synchronous Code Division Multiple
Access
3GPP:3rd Generation Partnership Project
LTE: Long Term Evolution
The LTE specification provides downlink peak rates of 300 Mbit/s,
uplink peak rates of 75 Mbit/s
QoS provisions permitting a transfer Latency of less than 5 ms in
the radio access network
Future !!
Next-generation Cellular
Wireless Internet Access
Wireless Multimedia
Sensor Networks
Smart Homes/Spaces
Automated Highways
In-Body Networks
All this and more
Standards
Interacting
systems require
standardization
Companies
want their systems
adopted as standard
Alternatively try for de-facto
standards
Standards
are determined by TIA/CTIA
in US
IEEE standards often adopted
Spectrum Regulation
Spectrum
a scarce public resource,
hence is allocated
Spectral
allocation in US controlled by
FCC (commercial) or OSM (defense)
Some
spectrum set aside for universal
use
Worldwide
spectrum controlled by ITU-
The Electromagnetic
Spectrum
Types of Wireless
Networks
Usually types of wireless networksare
defined on the bases of
Their size/range
Their number of machines
The speed of data transfer.
terms of coverage
area
Wireless PAN Personal
area network Wireless
Personal Area Networks
Wireless LAN Local Area
Network
Wireless MAN
Metropolitan Area
Networks
Wireless WAN- Wide Area
Network
Notice the IEEE Standards numbers in each case!!
Wireless PAN
Wireless Personal Area Networks
Such networks interconnect devices in small
premises usually within the reach of a person
for example
Invisible infra red light
Bluetooth radio interconnects
Headphone to a laptop by the virtue of WPAN.
Wi-Fi into customer electronic devices
Wireless LAN
The simplest wireless distribution method
that is used for interlinking two or more
devices providing a connection to wider
internet through an access point. (100m
range)
LANs data transfer speed is typically 10
Mbps for Ethernet and 1 Gbps for Gigabit
Ethernet.
LANs could accommodate as many as
hundred or even one thousand users.
OFDM or other spread-spectrum
Wireless MAN
Thewireless networkthat is used to connect
at high speed multiple wireless LANs that
are geographically close (situates anywhere
in a few dozen kilometers).
The network allows two or more nodes to
communicate with each other as if they
belong to the same LAN.
The set up makes use of routers or switches
for connecting with high-speed links such as
fiber optic cables.
Wireless WAN
WAN is the wireless network that usually covers
large outdoor areas.
The speed on such network depends on the cost
of connection that increases with increasing
distance.
The technology could be used for
interconnecting the branch offices of a business
or public internet access system.
Developed on 2.4GHz band these systems
usually contain access points, base
station/gateways and wireless bridging relays.
The point of the classification is not to partition each technology into a separate bin, but to
highlight the high-level differences within each use case. For Example
Some devices have access to a continuous power source; others must optimize their battery
life at all costs.
Some require Gbit/s+ data rates; others are built to transfer tens or hundreds of bytes of
data.
Some applications require always-on connectivity, while others are delay and latency
tolerant.
These and a large number of other criteria are what determine the original characteristics of each
type of network.
Architecture of
Wireless Networks
The architecture of a network defines the protocols and
components necessary to satisfy application
requirements. Seven-layer Open System Interconnect
(OSI) Reference Model, developed by the International
Standards Organization (ISO) specifies a complete set
of network functions. These functions reside within
each network component.
Architecture of
Wireless Networks
The architecture of a network defines the protocols and
components necessary to satisfy application
requirements. Seven-layer Open System Interconnect
(OSI) Reference Model, developed by the International
Standards Organization (ISO) specifies a complete set
of network functions. These functions reside within
each network component.
The basic difference in
OSI (Or TCP/IP) model
of a wired and wireless
network lies on the
lower three layers
Open System Interconnect
(OSI) Reference Model
Layer 7Application layer: Establishes communications among users and provides basic communications services such
as file transfer and e-mail. Examples of software that runs at this layer include Simple Mail Transfer Protocol (SMTP),
HyperText Transfer Protocol (HTTP) and File Transfer Protocol (FTP).
Layer 6Presentation layer: Negotiates data transfer syntax for the application layer and performs translations between
different data formats, if necessary. For example, this layer can translate the coding that represents the data when
communicating with a remote system made by a different vendor.
Layer 5Session layer: Establishes, manages, and terminates sessions between applications. Wireless middleware and
access controllers provide this form of connectivity over wireless networks. If the wireless network encounters interference,
the session layer functions will suspend communications until the interference goes away.
Layer 4Transport layer: Provides mechanisms for the establishment, maintenance, and orderly termination of virtual
circuits, while shielding the higher layers from the network implementation details. In general, these circuits are connections
made between network applications from one end of the communications circuit to another (such as between the web
browser on a laptop to a web page on a server). Protocols such as Transmission Control Protocol (TCP) operate at this
layer.
Layer 3Network layer: Provides the routing of packets though a network from source to destination. This routing
ensures that data packets are sent in a direction that leads to a particular destination. Protocols such as Internet Protocol (IP)
operate at this layer.
Layer 2Data link layer: Ensures medium access, as well as synchronization and error control between two entities. With
wireless networks, this often involves coordination of access to the common air medium and recovery from errors that might
occur in the data as it propagates from source to destination. Most wireless network types have a common method of
performing data link layer functions independent of the actual means of transmission.
Layer 1Physical layer: Provides the actual transmission of information through the medium. Physical layers include
radio waves and infrared light.
Architecture of
Wireless Networks
Each layer of the OSI model supports the layers above it. Usually
Wireless networks are directly implement only on the lower layers
of the model.
The actual transmission of data occurs at physical layer. Frames
that are sent by the physical layer actually contain frames from all
higher layers. At the destination, each layer passes applicable
frames to higher layers to facilitate the protocol between peer
layers.
A wireless NIC, for example, implements the data link layer
and physical layer functions.
The lower layers often appear transparent to the layers above.
For example, TCP operating at the transport layer establishes
connections with applications at a distant host computer,
without awareness that lower layers are taking care of
Fundamentals of
Wireless Networks
Each and every typeof wireless technology has
its own set of constraints and limitations.
However, all communication methods have a
maximum channel capacity.
Claude E. Shannons mathematical model
determines channel capacity, regardless of the
technology in use.
C=BWlog2(1+S/N)
Fundamentals of
Wireless Networks
In General following 3 parameters affect the performance
of a wireless network
Bandwidth
Signal Power
Modulation Technique
Few factors that may affect the performance of a wireless
network:
Amount of distance between receiver and sender
Amount of background noise in current location
Amount of interference from users in the same network
(intra-cell)
Amount of interference from users in other, nearby
networks (inter-cell)
Bandwidth
Unlike wired network, radio communication uses a shared medium:
radio waves or electromagnetic radiation. Both the sender and
receiver must agree on the specific frequency range over which the
communication will occur. For example, the 802.11b and 802.11g
standards both use the 2.42.5 GHz band across all WiFi devices.
Usually local government determines the frequency range and its
allocation. (For eg Federal Communications Commission (FCC) in
US). Different countries often assign different spectrum ranges to
the same wireless technology.
Size of the assigned frequency range is an important performance
factor. As Shannons model shows, the overall channel bit rate is
directly proportional to the assigned range.
Ex: going from 20 to 40 MHz of bandwidth can double the channel data
rate, which is exactly how 802.11n is improving its performance over
earlier WiFi standards!
Finally, it is alsoworth noting that not all frequency ranges offer the
same performance.
Low-frequency signals travel farther and cover large areas (macrocells),
Signal Power
Signal-power-to-noise-power, S/N ratio, or SNR is an important
limiting factor in all wireless communication. It is a measure that
compares the level of desired signal to the level of background
noise and interference.
The larger the amount of background noise, the stronger the
signal has to be to carry the information.
Other devices may generate unwanted interference. For example,
A microwave oven operating at 2.5 GHz may overlap with the
frequency range used by WiFi, creating cross-standard
interference.
Other WiFi devices, such as your neighbors' WiFi access point, and
even your coworkers laptop accessing the same WiFi network,
also create interference for your transmissions.
Also
the distance affect the signal power.
Attenuation increases with distances
To achieve the desired data rate where interference is present,
Modulation
Modulationis the process of varying one or more properties of a
periodicwaveform, called thecarrier signal, with a modulating signal
that typically contains information to be transmitted.
Modulation is the process of conveying a message signal, for example a
digital bit stream or ananalogaudio signal, inside another signal that
can be physically transmitted.
Amodulatoris a device that performs modulation. Demodulator is a
device that performs the inverse of modulation.
Amodem(frommodulatordemodulator) can perform both operations.
The combination of the alphabet and the symbol rate is what then
determines the final throughput of the channel. For example:
Receiver and sender can process 1,000 pulses or symbols per second
=1,000 baud.
If Each transmitted symbol represents 2-bit alphabet (e.g., : 00, 01,
10, 11).
Then the bit rate of the channel is 1,000 baud 2 bits per symbol, or
Modulation
The aim of Analog modulation is to transfer an analog baseband (or low pass) signal,
for example an audio signal or TV signal, over an analog band pass channel at a
different frequency, for example over a limited radio frequency band or a cable TV
network channel.
The aim of Digital modulation is to transfer a digital bit stream over an analog band
pass channel, for example over the public switched telephone network (where a band
pass filter limits the frequency range to 3003400 Hz) or over a limited radio frequency
band.
The choice of the modulation algorithm depends on the available technology, computing
power of both the receiver and sender, as well as the SNR ratio
Wireless devices
Wireless technology defines the electronic devices that communicate in air
without cables using radio frequency signals. On general the wireless
devices are:
Wireless Router
Wireless routers accepts an incoming Internet connection and sends
the data as RF signals to other wireless devices that are near to the
router. A network set up with a wireless router is called as a Wireless
Local Area Network (WLAN).Many routers have built-in security
features such as firewalls that help protect devices connected to the
router against malicious data such as computer viruses.
A wireless router is used in many houses to connect their computers
to the Internet.
Wireless Adapters
Wireless adapters are hardware devices that are installed inside
computers which enables wireless connectivity. If a computer does
not have a wireless adapter, it will not be able to connect to a router
in order to access the Internet.
Wifi Devices
AP = Access Point L2 bridge (802.1d)
between wired (802.3) & wireless (802.11)
STA = Station 802.11 NIC (PHY in form
of PC Card, USB, PCI, etc.) Mini PCI for Laptops and Embedded
WiFi PC cards
Examples of Wireless
Networks
Broadcast radio
Radio broadcastingis aonewaywirelesstransmission overradio
wavesintended to reach a wideaudience.
A broadcast sends information over long distances
at up to two megabits/Sec (AM/FM Radio).
Examples:
Cable radio,
Local wire television networks,
Satellite radio,
Internet radio via streaming
media on the Internet.
Broadcast radio
Microwave
Communication
Microwave wireless communicationis an effective
type of communication,
Mainly Uses radio waves, and the wavelengths of
radio waves are measured in centimeters. In this
communication, the data or information can be
transferred using two methods. One is satellite
method and another one is terrestrial method.
The main disadvantage of microwave signals is, they
can be
affected by bad weather, especially rain.
Satellite
Communication
Satellite Communication Cover very large areas (ex:
GPS)
Data can be transmitted though a satellite, that orbit
22,300 miles above the earth..
There are about 750 satellite in the space,
Transmission delay is about 0.3 sec.
Stations on the earth send and receive data signals from
the satellite with different frequency ranging and with a
transmission speed of 1Mbps to 10Mbps
Satellite up links (4, 11 and 20 Ghz) and down links (6,
14 and 30Ghz)
Orbits:
LEO: Low Earth Orbit.
MEO: Medium Earth Orbit
GEO: Geostationary Earth Orbit
Infrared wireless
Communication
Infrared wireless communicationcommunicates
information in a device or systems through IR
radiation .
IR is electromagnetic energy at a wavelength that is longer than
that of red light.
IR cannot be travelled through obstacles in an infrared system, but
can be inhibited by light. Transmission is possible between two
points limited to a range and line of sight.
The normal frequency of IR broadcast system is 100 GHz to 1,000
THz with a limited speed ranges from 100 Kbps to 16 Mbps (on
average1 Mbps).
For a successful infrared communication, a photo
LED transmitter and a photo diode receptor are
required.
The LED transmitter transmits the IR signal in the
form of non visible light, that is captured and saved
Wifi
Wi-Fi is a low power wireless LAN communication, that is used by various
electronic devices like smart phones, laptops, etc.
In this setup, a router or AP works as a communication hub wirelessly. These
networks allow users to connect only within close proximity to a router.
WiFi is very common in networking applications which affords portability
wirelessly.
These networks need to be protected with passwords for the purpose of
security, otherwise it will access by others
ZigBee/ IEEE 802.15.4
Low-Rate
Data
WPAN
rates of 20, 40, 250 Kbps
Support
for large mesh networking
or star clusters
Support
for low latency devices
CSMA-CA
Very
channel access
low power consumption
Frequency
ZigBee
of operation in ISM bands
is used in Commercial
Applications like sensing and
Communication
System
Acellular networkormobile networkis a
wirelessnetworkdistributed over land areas called cells, each
served by at least one fixed-location transceiver, known as
acellsite or base station.
In a cellular network, each cell uses a different set of
frequencies from neighboring cells, to avoid interference and
provide guaranteed bandwidth within each cell.
When joined together these cells provide
radio
.
coverage over a wide geographic
area. This enables a large number of
portable transceiver (mobile phones) to
communicate with each other and with
fixed networks, via base stations,
Even if some of the transceivers are
moving through more than one cell during
transmission.
Bluetooth Technology
Bluetooth is a wireless PAN technology standard for exchanging data over
short distances (using short-wavelength UHF radio waves in the ISM band from
2.4 to 2.485 GHz) from fixed and mobile devices
Invented by telecom vendor Ericsson in 1994
Bluetooth operates at frequencies between 2400 and 2483.5 MHz
Bluetooth uses a radio technology called frequency-hopping spread spectrum.
(FHSS)
Bluetooth divides transmitted data into packets, and transmits each packet on
one of 79 designated Bluetooth channels. Each channel has a bandwidth of
1 MHz.
Ad-Hoc Networks
Peer-to-peer communications
No backbone infrastructure or
centralized control.
Does not rely on a pre existing
infrastructure, such as routers in
wirednetworksor access points
in managed (infrastructure) wirelessnetworks.
Routing can be multihop.
Topology is dynamic.
Fully connected with different link
Eg: WSN and MANETs
Open Challenges
Fundamental capacity region
Resource allocation (power, rate, spectrum, etc.)
