Download Wireless Networks and Mobile Communication Systems NET 332D

Wireless Networks and Mobile Communication
Systems
NET 332D
(PRIMER)
OUTLINE
› Computer Network and Elements of a Computer
Network
› Classification of Networks
› Host Role
› Geographical Proximity/Scale
› Signaling
› Network Topology
› Network Architecture/Protocol architecture
› Type of Communication Medium
› Guided Medium
› Unguided Medium
OUTLINE
› Why is Wireless Different than Wired Networks?
› Wired Versus Wireless
› Elements of a wireless Network
› Wireless Networking Technologies
Computer Network and Elements of a Computer Network
› Definition
› Two or more devices connected together to share resources.
› Devices: Laptops, PC, Tablet, Network Enabled Printers, mobile phones
etc.
› Connected via Media: Twisted Pair, Coaxial Cable, Ethernet Cable,
Wireless link
› Resources: Files, Webpages, Songs, Video, Facebook Statuses
› Elements of a Network
› Sender/Receiver (Nodes)
› Transmission Media
› Shared Resources
› Protocols
Classification of Networks
Host Roles: What does the host do in the network
› Client Server Model:
› Defined Roles of nodes: Client requests/consumes and host
provides network resources.
› Peer to Peer Model:
› Hosts can provide and consume network resources.
Geographical Proximity/Scale
– Local Area Network
› Small geographic area Example of classes, Inside the different floors of an
organization
› Governed by a single organization, Example: Home Network
› Size: Home devices versus a class devices versus a small corporation
› Small network administered by a single organization or individual who have a
common goal interest and set of resources: Example class meets to discuss 332D
so this class can be considered as one local area network
Classification of Networks
– Metropolitan area Network
› MANs are networks between a LAN and WAN.
› They are a type of interconnecting networks for big businesses in a metropolitan
area. Example: ABC Corp
– Wide Area Network
› Hosts in the network are very widely distributed geographically.
› Group of interconnected LANs geographically separated, e.g XYZ coop with
offices in different parts of the world. The employees in these offices are
connected together via a large internetwork or a WAN. Example: Internet
› Note: Local resources should reside locally in the local office so that a frequently
accessed resource in one office(reside on the local server) does not need to be
accessed via the WAN.
› Useful if the worker in one office needs to access some documents that reside in
another office.
› An inter-connection of connected LANS is a WAN.
– PAN
› PANs are networks interconnecting the devices of personal use that could, in
general, be carries around. Examples of such devices are personal digital
assistant (PDA), various wireless phones, remote control, etc.
› Usually, the design of these networks entails replacing the wire only, as they
aren't expected to be interconnected via WANs and MANs in near future.
Classification of Networks
Signaling
› Baseband Networks : One signal at a time on the channel, Entire
channel bandwidth utilized by one signal, No multiplexing. Example
Old PSTN.
– Broadband Networks: Medium bandwidth divided into multiple
channels. Multiplexing, Multiple signals being transmitted on the
channel at the same time.
Network Topology
› Ring, Star, Bus, Mesh and Hybrid topology.
Network Architecture
– Classification
of
a
network
Architecture/Protocol Architecture.
based
on
the
Network
Classification of Networks
› Protocol architecture/network architecture
–Protocol
› Protocol: Language or the Rules of communication
–Standards
› Standards are protocols that have gone through a standardization
process and after standardization it has been documented by
some organization
–Standardization Agencies
›
›
›
›
›
›
Internet society
International organization for standardization (ISO)
IEEE Institute of Electrical and Electronics Engineer
ANSI American Standards Institute
ETSI Euro Telecomm Standards Institute
ITU International Telecomm Union
Classification of Networks
› Protocol architecture/network architecture
–Network architecture
› Each network can be defined and thus be classified as a set of
protocol and layers.
› Such a set of protocols is called the Network or Protocol
architecture.
› Network architecture is a set of layer and associated protocols
that can achieve complete communication among the nodes in
that network.
–How to study a network
› Define the network Layers
› Define all the protocol layers
› Define interconnection between layers
What is the OSI Reference Model
13
› The OSI Reference Model is a seven-layer
conceptual model developed by ISO in 1984.
–Describes the standards for inter-computer
communication.
› The seven layers of the OSI model are:
–Application
–Presentation
–Session
–Transport
–Network
–Data link
–Physical
Computer networks / Andrew S. Tanenbaum-- 5th ed
What is the OSI Reference Model
14
Computer networks / Andrew S. Tanenbaum-- 5th ed
Classification of Networks
› In a data transmission system, the transmission medium is the physical
path between transmitter and receiver.
› Transmission media can be classified as:
– Guided medium
– Unguided medium
› In both cases, communication is in the form of electromagnetic waves.
› The electromagnetic spectrum and indicates the frequencies
› at which various guided media and unguided transmission techniques
operate.
› Guided Medium
– With guided media, the waves are guided along a solid medium, such as copper
twisted pair, copper coaxial cable, or optical fiber.
› Unguided Medium
– The atmosphere and outer space are examples of unguided media,
which provide a means of transmitting electromagnetic signals but
do not guide them; this form of transmission is usually referred to as
wireless transmission.
Guided Medium
Bounded Media/Guided Media
› Coaxial
› Coaxial Cable (Not commonly
used now)
› Data rate limited to 10Mb/s
› Twisted Pair Cable(UTP )
› Used in Wired Ethernet standard
so called Ethernet Cable.
› Suffers from EMI
› Flexible and Inexpensive
› Shielded Twisted Pair
(STP)
› Rates Cat 3 10-16Mbps
› Rates Cat 5 100-1000Mb/s
› Rates Cat 5c 10,000Mbps
› Fiber Optic cable
› No EMI
› Very expensive Hard
installation
› Not flexible (Breaks and bends
easily)
Unguided Medium
› For unguided media, transmission and reception are achieved by
means of an antenna.
› For transmission, the antenna radiates electromagnetic energy into the
medium (usually air), and for reception, the antenna picks up
electromagnetic waves from the surrounding medium.
› Three general ranges of frequencies are of interest in wireless
transmission.
› Microwave: Frequencies in the range of about 1 GHz (gigahertz
= 109 Hz) to100 GHz are referred to as microwave frequencies.
At these frequencies, highly directional beams are possible, and
microwave is quite suitable for point-to-point transmission.
Microwave is also used for satellite communications.
› Radio Range: Frequencies in the range 30 MHz to 1 GHz are
suitable for omnidirectional applications.
› The infrared portion of the spectrum. This covers, roughly, from
3 × 1011 to 2 × 1014 Hz. Infrared is useful in local point-to-point
and multipoint applications within confined areas, such as a
single room.
Terrestrial Microwave
› Line-of-sight transmission
› Common frequencies used for transmission are in the range 2 to 40
GHz.
› Applications:
– Long-haul telecommunications service, as an alternative to coaxial
cable or optical fiber.
– Short point-to-point links between buildings. This can be used for
closed-circuit TV or as a data link between local area networks.
– Cellular systems
Satellite Microwave
› A communication satellite is, in effect, a microwave relay station. It is
used to link two or more ground-based microwave transmitter/receivers,
known as earth stations, or ground stations.
› The optimum frequency range for satellite transmission is in the range 1
to 10 GHz.
› Applications
– Television distribution
– Long-distance telephone transmission
– Private business networks
Infrared
› Infrared communications is achieved using transmitters/receivers
(transceivers) that modulate infrared light.
› Transceivers must be within the line of sight of each other either directly
or via reflection from a light-colored surface such
› as the ceiling of a room.
› One important difference between infrared and microwave transmission
is that the former does not penetrate walls. Thus the security and
interference problems encountered in microwave systems are not
present.
› Furthermore, there is no frequency allocation issue with infrared,
because no licensing is required.
Types of Communication
›Types of Communication
› Simplex
– (one way communication, Example: Broadcast Radio)
› Half Duplex
– (Two way communication but not at the same time, Example: CB Radio)
› Full Duplex:
– Two way communication but at the same time. Example Telephone and cellular
phones.
Why is wireless different than wired?
› Noisy, time-varying channel
– Environnemental conditions affect transmission
› Shared medium
– Other users create interference
– Must develop ways to share the channel
› Bandwidth is limited
– FCC determines how spectrum is allocated
– ISM band for unlicensed use (902-928 MHz, 2.4-2.5 GHz and 5.725-5.875 GHz)
– Requires intelligent way to make efficient use of limited bandwidth in error-prone environment
› Major differences due to broadcast nature of wireless communication
– Transmitted signals can be received by an arbitrary (and perhaps unknown) number of other
users
– Cannot guarantee a link from every transmitting node to every intended receiving node
› Each transmitted message utilizes scares resources (BW)
– Need to provide means for fair and efficient utilization of available bandwidth among transmitting
nodes
› Transmitted signal power important parameter
– Require enough signal power to reach destination node.
– Want to limit signal power to minimize interference and max battery life.
WIRED VERSUS WIRELESS
Advantages:
People want connectivity anywhere anytime for example, at airports, hotels,
customers place, or group of people wants to share data at any location. Such
requirements have made the wireless connectivity indispensable.
– Convenience: Access your network resources from any location within your wireless network's
coverage area or a wireless hot spot
– Mobility: You're no longer tied to your desk, as you were with a wired connection. You and your
employees can go online in conference room meetings, for example.
– Productivity: Wireless access to the Internet and to your company's key applications and
resources helps your staff get the job done and encourages collaboration.
– Easy setup: You don't have to string cables, so installation can be quick and cost-effective.
– Expandable: You can easily expand wireless networks with existing equipment, while a wired
network might require additional wiring.
– Cost. Because wireless networks eliminate or reduce wiring costs, they can cost less to operate
than wired networks.
WIRED VERSUS WIRELESS
Disadvantages:
– Wireless LANs using 802.11b support a maximum theoretical bandwidth of 11 Mbps, roughly the
same as that of old, traditional Ethernet. 802.11a and 802.11g WLANs support 54 Mbps , that is
approximately one-half the bandwidth of Fast Ethernet.
– In theory, wireless LANs are less secure than wired LANs, because wireless communication
signals travel through the air and can easily be intercepted.
– Wireless LANs suffer a few more reliability problems than wired LANs, though perhaps not enough
to be a significant concern. 802.11b and 802.11g wireless signals are subject to interference.
– One medium shared by all the users.
– Signal attenuation is high
– High interference i.e noise; co-channel interference; adjacent channel interference etc
ELEMENTS OF A WIRELESS NETWORK
ELEMENTS OF A WIRELESS NETWORK
ELEMENTS OF A WIRELESS NETWORK
WIRELESS NETWORKING TECHNOLOGIES
› Wireless Communication applies across a wide range of network types
and size.
› Many wireless communication technologies exist and are used to create
Wireless LAN, MANs, WANs and PANs.
› Wireless technologies can be classified broadly according to the network
type as:
› PANS
– PAN technology provides communication over a short distance and is
intended for use with devices that are owned by or operated by a
single user. e.g: Communication between a wireless handset and cell
phone. Computer and a nearby wireless mouse or keyboard.
PAN Technologies and Standards
› Bluetooth: (802.15.1.a) IEEE standard for short distance
wireless communication technology
› Zigbee: (802.15.4) is a wireless remote control technology
(not data) especially for industrial equipment. Remote
control sends only short commands so high data rates are
not required. Applications industry and home automation.
Other short distance communication
technologies
› Wireless technologies (not grouped under PANs) but used
for short distance wireless communication
– InfraRED: InfraRed technology used often in remote controls may
also be used as a cable replacement.
– IrDA(Infrared data association produced a set of standards for
infraRed communication.
› Some characteristics
– Various speeds and purposes
– Data rates between 2.4Kbps (control) and 16Mbps for data.
– Low power consumption and signals can not penetrate solid
objects.
– LOS (Line of sight)
› RFID: Radio Frequency Identification
– Wireless Communication primarily used for inventory and shipping
– RFID technology uses an interesting form of wireless
Wireless LAN Technology
› A variety of wireless LAN technologies exist that use
various frequencies, modulation techniques and data rates.
› IEEE provides the Wireless LAN standards which are
categorized as IEEE 802.11.
Wireless MAN Technology and WIMAX
› WIMAX is a (family of standards based on the IEEE
802.16) wireless MAN technology standardized under the
IEEE standard 802.16.
› WIMAX offers broadband communication.
› Two main versions of WIMAX are the
– Fixed WIMAX-standard 802.16-2004
› Designed to provide between service providers and a fixed
location such as a residence or a building.
– Mobile WIMAX-standard 802.16e-2005
› Mobile WIMAX system can be used with portable devices such
as laptop computers or cell phones
Wireless WAN technologies
› Wireless Wan technologies can be divided into two
categories:
– Cellular Communication systems
– Satellite Communication systems