wireless comm principles
TRANSCRIPT
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Wireless Communication Principles
9th
& 10th
December 2010
Prepared & Presented by Ir. Senthilathiban Thevarasa
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Wireless Communication Basics
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Telecommunication Telecommunication is the distant transfer of meaningful information from
one location (the sender, transmitter, or source) to a second location (the
receiver, or destination).
Wireless communication is the transfer of information without the use of
wires.
Radio ~ American version, Wireless ~ British version
A wireless communication link includes a transmitter, a receiver, and a
channel.
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Block Diagram Wireless Link
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Standards Organizations
Standards are documented agreements containing technical specifications
or other precise criteria to be used consistently as rules, guidelines, or
definitions of characteristics to ensure that the products, processes, and
services are fit for their purpose.
The broad goal of setting standards for the telecommunications industry is
connectivity, compatibility, and open networking of communications and
computer systems from multiple vendors.
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Wireless Communication Concepts
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Simplex, Half-duplex, & Full-duplex
Simplex
Half-duplexFull-duplex
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Analogue Signals Analog signals are continuous electrical signals that vary in time.
An analog signal can be represented as a series of sine waves.
wavelength
1 cycle
Frequency: Is the rate of change, the signal undergoes every second, Hertz
(Hz) / cycles per seconds.
A cycle is 1 complete movement of the wave, from its original start position
back to the same point again.
The number of cycles / waves within one second time interval is called
cycles-per-seconds or Hertz.
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Digital Signals Digital signals are represented as a sequence of discrete symbols from a
finite text and/or digits.
Digital signals consist of patterns ofbits of information. These patterns canbe generated in many ways, each producing a specific code.
The rate & capacity of a digital signal is measured in bits per second
(bps).
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Connection-Oriented Communication
Connection-oriented describes a means of transmitting data in which the
devices at the end points use a preliminary protocol to establish an end-to-end connection before any data is sent.
Connection-oriented protocol service is sometimes called a "reliable"
network service, because it guarantees that data will arrive in the proper
sequence.
Transmission Control Protocol (TCP) is a connection-oriented protocol.
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Connectionless-Oriented CommunicationConnectionless describes communication between two network end points in
which a message can be sent from one end point to another without priorarrangement.
The device at one end of the communication transmits data to the other,
without first ensuring that the recipient is available & ready to receive the data.
The device sending a message simply sends it addressed to the intended
recipient.
The Internet Protocol (IP) and User Datagram Protocol (UDP) are
connectionless protocols
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Connection-Oriented vs. Connectionless
Communication
Connection
Oriented
Connectionless
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Circuit Switched Data Network
In a circuit-switched network, before communication can occur between
two devices, a circuit is established between them. This is shown as a thick blue line for the conduit of data from DeviceA to
Device B, and a matching purple line from B back toA.
Once set up, all communication between these devices takes place over
this circuit, even though there are other possible ways that data could
conceivably be passed over the network of devices between them.
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Packet Switched Data Network
In a packet-switched network, no circuit is set up prior to sending data
between devices.
Blocks of data, even from the same file or communication, may take any
number of paths as it journeys from one device to another.
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Packet Switched vs. Circuit Switched
Data Network
Advantage Disadvantage
Circuit Switching 1. Ideal for real-time
applications such asvoice
1. Inefficient use of channel
capacity2. Susceptible to
eavesdropping
3. Inappropriate for data
communication
Packet Switching 1. Efficient use ofnetwork
Facilities.
2. Most appropriate for
data communication
1. Real-time applicationssuch as voice and video
conferencing may suffer
from poor quality of service
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Open System Interconnection Model (OSI)
Bits
Frames
Packets
Segments
Data
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Transmitting Media
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Transmission Media In telecommunications, transmission is the process of sending, propagating
and receiving an analogue or digital information signal over a physical point-
to-point or point-to-multipoint transmission medium, either wired or
wireless.
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Transmission Media
Coaxial Cable
This design provides the coaxial cable with a special advantage; electrical
interference is reduced because the two conductors are shielded and
confined separately.
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Transmission Media
Twisted Pair Cable
Twisted pair cabling is made of pairs of conductors that are twisted
together, & most networks are connected with twisted pair cabling.
The twisting insures that the transmitted signals are protected from
electrical & magnetic interference.
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Transmission Media
Fiber Optic Cable
Fiber optic / ("optical fiber") refers to the medium & the technology
associated with the transmission of information as light impulses along a
strand of glass.
Fiber optics are tap proof, protected from interference, suitable for long
distance & have a high rate of transmission.
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Transmission Media
Satellites Systems
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Transmission Media
Microwave Radios
Microwave is a radio system, which uses very high frequencies to send &
receive data.
Stations are located about 30 Km apart & in line of sight (LOS).
Microwave systems have sufficient bandwidth capacity to support large
number of voice channels.
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Transmission Media
Infrared Communication
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Organizations of the Networks
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Local Area Network A LAN supplies networking capability to a group of computers in close
proximity to each other such as in an office building, a school, or a home.
LAN network are limited spatially only a few kilometers & can transmit dataat high speed.
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LAN
Characteristics A suite of application programs can be kept on the LAN server. Users who
need an application frequently can download it once & then run it from theirlocal hard disk.
Users can order printing & other services as needed through applications run
on the LAN server.
A user can share files with others at the LAN server; read & write access is
maintained by a LAN administrator.
A LAN server may also be used as a Web server if safeguards are taken tosecure internal applications & data from outside access.
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Wide Area Network (WAN) The WAN connects data processors with servers within one or several
countries, In contrast to a LAN, WAN uses public lines & facilities for data
transfer. Its rate of transmission lies in the area of up to 2 Mbps. Using broadband
networks, rates up to 1 Gbps is possible.
WAN are always large networks. Usually works slower than LANs & normally
they belong to service providers, who sell their data services to end-users.
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WAN
Characteristics A computer network that spans a relatively large geographical area.
Typically, a WAN consists of two or more local-area networks (LANs). Computers connected to a wide-area network are often connected through
public networks, such as the telephone system. They can also be connected
through leased lines or satellites.
The largest WAN in existence is the Internet.
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Metropolitan Area Network (MAN) A MAN is a special wide-area network, which is limited to an urban area or
to the area of a company. Mainly, it differs from WANs only in the rates of
transmission.
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Characteristics of LAN, MAN, & WAN
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Virtual Area Network (VPN) A VPN is a network that uses a public telecommunication infrastructure, such
as the Internet, to provide remote offices or individual users with secure
access to their organization's network.
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Broadband Concepts
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Broadband Technology Overview
High-speed Internet access that is always on & faster than the traditional
dial-up access.
It allows more content to be carried through the transmission pipeline
It does not block phone lines & there is no need to reconnect to network
after logging off.
Less delay in transmission of content when using broadband.
Fixed Line Technologies or Wireless Technologies.
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Types of Broadband Connections
DSL
Wire line transmission technologythat transmits data faster over
traditional copper telephone lines
already installed to homes &
businesses
Provides transmission speeds ranging
from several hundred Kbps to
millions of bits per second (Mbps).
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Types of Broadband Connections
ADSL/SDSL
Asymmetrical DSL
Symmetrical DSL
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Types of Broadband Connections
HDSL/VDSL
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Types of Broadband Connections
Cable Modem A device used to connect a computer to a cable TV service for Internet
access.
Compared to analog dial-up, cable Internet dramatically increases the
bandwidth between the user's computer & the Internet.
In order to prevent users with lower-cost cable access from hosting high-
traffic Web servers, the upload speed is approximately 5 times slower thanthe download speed.
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Types of Broadband Connections
Cable Modem System
Cable modems connect to the computer
via an Ethernet port, which is an
always-on connection. Ethernet is a
shared medium, & the individual user's
speed will vary depending on how many
customers are sending or receiving data
on that cable segment at the same
time.
Subscribers can access their cable
modem service by simply turning ontheir computers, without dialing-up an
ISP.
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Types of Broadband Connections
Fiber
Fiber optic technology convertselectrical signals carrying data to light &
sends the light through transparent glass
fibers about the diameter of a human
hair.
Fiber transmits data at speeds far
exceeding current DSL or cable modem
speeds, typically by tens or even
hundreds of Mbps.
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Types of Broadband ConnectionsFiber Passive Optical Network (PON)
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Types of Broadband ConnectionsFiber Various P2P PON
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Types of Broadband ConnectionsWireless
Wireless broadband connects a home or business to the Internet using a
radio link between the customers location & the service providers facility.
Wireless broadband can be mobile or fixed.
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Types of Broadband ConnectionsSatellite
Satellite broadband is still infancy
& is set up using a satellite dish.
Both one-way (download only) &
a two-way satellite internet
connection are available.
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Types of Broadband ConnectionsBroadband Over Powerline(BPL)
With BPL, you can plug yourcomputer into any electrical
outlet in your home & instantly
have access to high-speed
Internet.
Combining the technological
principles of radio, wireless
networking, & modems,
developers have created a way to
send data over power lines & into
homes at speeds between 500
kilobits & 3 megabits per second
(equivalent to DSL and cable).
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Types of Broadband ConnectionsBPL Modem
The BPL modem simply plugs into the wall & then into your
computer, these modems are capable of speeds comparable to DSL or
cable modems
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Types of Broadband ConnectionsBroadband Summary
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Radio Frequency Fundamentals
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RF Definition Radio frequencies are high frequency alternating current (AC) signals that are
passed along a copper conductor and then radiated into the air via an antenna.
RF B h i
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RF Behaviors
Gain The term used to describe an increase in an RF signal's amplitude.
Peak amplitude before Gain
Peak amplitude after Gain
Gain as seen by
an oscilloscope
Gain of DSSS as seen by
Spectrum analyzer
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RF Behaviors
Loss Loss describes a decrease in signal strength
Peak amplitude after Loss
Peak amplitude before Loss
Gain as seen by
an oscilloscope
Gain of DSSS as seen by
Spectrum analyzer
RF B h i
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RF Behaviors
Reflection Reflection occurs when a propagating electromagnetic wave impinges upon
an object that has very large dimensions when compared to the wavelength of
the propagating wave.
RF B h i
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RF Behaviors
Refraction Refraction describes the bending of a radio wave as it passes through a
medium of different density.
RF B h i
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RF Behaviors
Diffraction Diffraction occurs when the radio path between the transmitter and receiver
is obstructed by a surface that has sharp irregularities or an otherwise rough
surface.
RF B h i
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RF Behaviors
Scattering Scattering occurs when the medium through which the wave travels consists
of objects with dimensions that are small compared to the wavelength of the
signal, and the number of obstacles per unit volume is large.
Incoming RFScattered RF
RF Behaviors
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RF Behaviors
Absorption Absorption occurs when the RF signal strikes an object and is absorbed into
the material of the object in such a manner that it does not pass through,
reflect off, or bend around the object.
Incoming RF
Absorbed RF
P i i l f A t
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Principles of Antenna Antennas convert electrical energy into RF waves in the case of a
transmitting antenna, or RF waves into electrical energy in the case of a
receiving antenna.
LOS ~ Line of Sight, apparently straight line from the object in sight (the
transmitter) to the observer's eye (the receiver).
Principles of Antenna
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Principles of Antenna
Fresnel Zone It defines an area around the LOS that can introduce RF signal interference
if blocked.
Units of Measure
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Units of Measure
Watts (W) ~ One ampere (A) of current at one volt (V)
Miliwatt ~ 1/1000 watt
Decibels ~ Allow us to represent these numbers by making them more
manageable and understandable. Decibels are based on a logarithmic
relationship to the previously explained linear measurement of power: watts.
dBm ~ Converting mWto dBm: & Converting dBmto mW:
dBi ~ The unit of measurement dBirefers only to the gain of an antenna. The
dBimeasurement is used in RF calculations in the same manner as dB. Units ofdBiare relative.
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Cellular Technologies
R di /C ll l C t & D fi iti
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Radio/Cellular Concepts & Definition
Cellular systems offer location-independent voice communications:
~users can move freely while talking
~they can place calls at any time and any place
~they can be called everywhere
Early mobile radio systems - Cover a large area by using a single, high
powered transmitter with an antenna mounted on a tall tower.
Replacing a single, high power transmitter (large cell) with many low power
transmitters (small cells).
Available channels can be reused as many times as necessary.
Key components that make up cellular systems;
~The cellular layout
~A network of radio base stations and antennas
~BSC which manage several BTS
~MSC, which gathers traffic from dozens of cells & pass it on to PSTN
Radio/Cellular Concepts & Definition
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Radio/Cellular Concepts & Definition
Interference Radio Interference is when co-channel, same channel, or and adjacent
channel degrades call quality.
Radio/Cellular Concepts & Definition
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Radio/Cellular Concepts & Definition
Fading Caused by interference between 2 or more versions of the transmitted
signals, which arrives at the receiver at different times.
Radio/Cellular Concepts & Definition
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Radio/Cellular Concepts & Definition
Techniques to Reduce Interference
Equalization a method used to extract desired signals from unwantedreflections
Frequency Hopping allows to change frequency alternatively
Interleaving & Channel Coding adds redundancy bits
Power Control
Timing Advance
Wireless Standards
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Wireless Standards
Wireless Standards
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Wireless Standards
Working Group/Organizations
Bluetooth SIG (Special Interest Group) - A volunteer-based organizationfacilitated by members of various companies. Oversee a number of working
groups that focus on specific areas or wireless technology such as
qualifications, engineering & marketing.
The IEEE (Institute of Electrical and Electronics Engineers) - an organization
that conducts extensive research in a broad spectrum of technologies.
WAP (Wireless Application Protocol) Forum -
WECA (Wireless Ethernet Compatibility Alliance)
Wi l St d d
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Wireless Standards
GSM
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GSM GSM is a globally accepted standard for digital cellular communication.
The GSM system is a frequency- and time-division cellular system, each
physical channel is characterized by a carrier frequency and a time slot
number.
GSM
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GSM
Phase 2+
GSM Architecture
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GSM Architecture
GSM
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GSMMobile Station (MS)
2 different entities Mobile Equipment & SIM
Output power 2 W
Subscriber Identity Module (SIM) Is implemented as a smart card
Mobile Identification Numbers
International Mobile Equipment ID (IMEI) each MS is permanently stored
with a ID. Can be used to determine if a unit is stolen or faulty.
Mobile Subscriber ISDN Number (MSISDN) Is a dial able number that callers
use to reach mobile subscribers.
International Mobile Subscriber Identity (IMSI) Is a unique non-dial able
number allocated to each mobile subscriber in GSM system.
GSM
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GSMHandovers
GSM
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GSMEvolution
WAP
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WAP Is a suite of communication protocols for the wireless & mobile devices
designed to access the internet independent of manufacturer, vendor, &
technology.
WAP bridges the gap between the mobile world & the Internet as well as
corporate intranets, & offers the ability to deliver an unlimited range of mobile
value-added services to subscribersindependent of their network, bearer, &
terminal.
GPRS
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GPRS Is a new non-voice, value added, high-speed, packet-switching technology,
for GSM networks.
It makes sending and receiving small bursts of data, such as email and webbrowsing, as well as large volumes of data over a mobile telephone network
possible.
EDGE
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EDGE Is a radio based high-speed mobile data standard which acts as an
enhancement for GPRS networks.
EDGE (also known as EGPRS) is a superset to GPRS & can function on anynetwork with GPRS deployed on it, provided the carrier implements the
necessary upgrades.
EDGE is a technology that gives GSM the capacity to handle services for the
third generation of mobile telephony. EDGE provides three times the data
capacity of GPRS.
3G
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3G
1G - period began in the late 1970s & lasted through the 1980s. It transmit
only analog voice information. The most prominent systems AMPS, NMT, &
TACS.
2G - began in the 1990s, & much of this technology is still in use. The 2G
cell phone features digital voice encoding. Examples include CDMA, TDMA,
and GSM. Since its inception, 2G technology has steadily improved, with
increased bandwidth, packet routing, & the introduction of multimedia. Thepresent state of mobile wireless communications is often called 2.5G.
Characteristics of 3G
~ High spectral efficiency
~ Used world wide for all mobile applications
~ Packet switch & Circuit switch~ Offers data rates up to 2Mbps
~ Improved mobility & coverage
The Benefits of 3G
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The Benefits of 3G
UMTS
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UMTSUMTS is envisioned as the successor to GSM. UMTS signals the move into the
third generation (3G) of mobile networks.
UMTS also addresses the growing demand of mobile an& Internet applications
for new capacity in the overcrowded mobile communications sky.
The new network increases transmission speed to 2 Mbps per mobile user &
establishes a global roaming standard.
UMTS, also referred to as wideband code division multiple access (WCDMA),
is one of the most significant advances in the evolution of telecommunications
into 3G networks.
Provides a vital link between todays multiple GSM systems & the ultimate
single worldwide standard for all mobile telecommunications, International
Mobile Telecommunications2000 (IMT2000).
UMTS Network Architecture
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UMTS Network Architecture Uu: UE to Node B (W-CDMA air interface)
Iu: RNC to Core Network (MSC & SGSN)
~ Iu CS~ Iu - PS
Iub: RNC to Node B
Iur: RNC to RNC
UTRAN
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U N
RNC Functions
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Node B Overview
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UMTS User Equipment
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q p
Classification of Handover in WCDMA
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Classification of Handover in WCDMA
Handover in 3G / UMTS are similar to those in GSM
Inter-System Handover
~ Handover to GSM & vice versa
Inter-Frequency Handover
~ handover between WCDMA carriers on different frequencies
Roadmap to 3G & Beyond
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p y
Roadmap of Wireless Communications
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Roadmap of Wireless Communications
Technologies
3G LTE
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3G LTELTE is a set of enhancements to the UMTS which will be introduced in 3rd
Generation Partnership Project (3GPP) Release 8. Much of 3GPP Release 8 will
focus on adopting 4G mobile communications technology, including an all-IPflat networking architecture.
WiMAX
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Worldwide Interoperability for Microwave Access (WiMAX)
WiMAX is a wireless digital communications system, also known as IEEE
802.16, that is intended for wireless "metropolitan area networks. WiMAX can provide broadband wireless access (BWA) up to 30 miles (50 km)
for fixed stations, and 3 - 10 miles (5 - 15 km) for mobile stations.
WiMAX
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Topologies Urban & Rural
Femto Cells
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Femto Architecture
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MIMO Technology
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Multiple-input & Multiple-output, MIMO is the use of multiple antennas at
both the transmitter & receiver to improve communication performance.
It offers significant increases in data throughput & link range withoutadditional bandwidth, or transmit power.
End of Presentation
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