wireless comm principles

7/30/2019 Wireless Comm Principles

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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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ADSL/SDSL

Asymmetrical DSL

Symmetrical DSL


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HDSL/VDSL


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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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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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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



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Interference Radio Interference is when co-channel, same channel, or and adjacent

channel degrades call quality.



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Fading Caused by interference between 2 or more versions of the transmitted

signals, which arrives at the receiver at different times.



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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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