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Media
Conducted media
Twisted Pair Wire
Coaxial Cable
Fiber Optic Cable

Wireless media

Twisted Pair Wire
Two or more pairs of single conductor wires that have been twisted around each other.
2,4, 8 wires(4+2+2, 4+4) insulated pairs of wire,
Eliminate electromagnetic interference
Shielding further help to eliminate interference. unshielded or shielded
Classifications:
Category: 1-5, 6 ,7 …

Twisted Pair Wire
Two Conductors are used, with second conductor providing the return path for the signal current.
Two wires can be
Open wire pair (parallel to each other ).
Unshielded twisted pair ( twisted ).
Shielded twisted pair (seldom used today).
Open wires are susceptible to cross talk and electromagnetic interference and are seldom used.
Long distance cables may contain hundreds of pairs (eg telephone cables).

Registered Jacks: RJ-11
The most common telephone jack
Likely to be the jack that your household or office phones are plugged into from the ordinary "untwisted" wire (sometimes called "gray satin" or "flat wire").
Your computer modem is usually connected to an RJ-11 jack in the wall.
Registered Jacks: RJ-45
A single-line jack for digital transmission over ordinary phone wire, either untwisted or twisted.
The interface has eight pins or positions.
Used with LANs.
Twisted Pair
Twisted Pair
100BASE-TX
100BASE-TX
100BASE-TX Crossover Wiring
Coaxial Cable
A single wire wrapped in a foam insulation surrounded by a braided metal shield, then covered in a plastic jacket. thick vs. thin.
Baseband coaxial: digital signal, Only one channel, 10Mbps
Broadband coaxial: analog signals, multiple channels, about 50 channels, 6Mhz

Coaxial Cable
Co-axial Cable
Coaxial Cable
Consists of two conductors separated from each other but contained in a jacket.
Much less vulnerable to interference and crosstalk than twisted pair and can be used over longer distances and at higher frequencies and data rates.
Coaxial Cable Connectors
Things and Tools
Fiber Optic Cable
A thin glass cable approximately a little thicker than a human hair surrounded by a plastic coating and packaged into an insulated cable.
Components:
Transmitter - Produces and encodes the light signals
A photo diode or light source generates pulses of light which travel down the fiber optic cable
Optical fiber - Conducts the light signals over a distance
Optical regenerator - May be necessary to boost the light signal (for long distances)
Optical receiver - Receives and decodes the light signals a photo receptor optic sensor
Fiber Optic Cable
Advantage:
Faster
Securer
Error free
No electromagnetic interference
No noise
From backbone to desktop

Fiber Optic Cable
Fiber Optic Cable
Multimode: the earliest fiber optic systems were, light could reflect inside the cable at many different angles.
Single mode fiber optic cables transmit a single direct beam of light through a cable that ensures the light only reflects in one pattern.
Transmission Modes

Wireless Media
Radio, satellite transmissions, and infrared light are all different forms of electromagnetic waves that are used to transmit data.

Each medium occupies a different set of frequencies, governed by FCC

Electromagnetic Radiation Spectrum
The electromagnetic radiation spectrum is the complete range of the wavelengths of electromagnetic radiation, beginning with the longest radio waves (including those in the audio range) and extending through visible light (a very small part of the spectrum) all the way to the extremely short gamma rays that are a product of radioactive atoms. electromagnetic radiation spectrum
Terrestrial Microwave
Transmit tightly focused beams of radio signals from one ground-based microwave transmission antenna (tower) (amplifiers) to another.
Popular with telephone companies and business to business transmissions
Features
Land-based
Line-of-sight transmission: each antenna must be in sight of the next antenna
Approximately 20-30 miles maximum between towers
Transmits data at hundreds of millions of bits per second
Lots of objects obstructing the path of transmission

Terrestrial Microwave

Satellite Microwave
Similar to terrestrial microwave except the signal travels from a ground station on earth to a satellite and back to another ground station.

Classified by how far out into orbit each one is
Low (L) and Middle (M) Earth Obit
Geosynchronous EO
Highly elliptical EO
When satellite is far out into space, it takes photos.
When satellite is close to earth, it transmits data.

Satellite Microwave
LEO - Low Earth Orbit - 100 miles to 1000 miles. Used for pagers, wireless e-mail, special mobile telephones, spying, videoconferencing.

MEO - Middle Earth Orbit - 1000 to 22,300 miles. Used for GPS and government.

GEO - Geosynchronous Orbit - 22,300 miles. Used for weather, television, and government operations.

HEO -; Highly Elliptical Orbit- variant miles. Used by the military for spying and by scientific organizations for photographing celestial bodies.

Satellite Microwave
MEO and GPS: Global positioning system
GPS: a system of 24 satellites launched by US Department of Defense and are used for identifying locations on earth.
By triangulation of signals from at least 4 GPS satellites (X,Y,Z, time), a receiving unit can pinpoint its current location to within a few meters anywhere on earth.
Satellite configuration
Bulk carrier configuration: one user, public ground stations

Multiplexed configuration: multi user, public ground stations

Single-user earth station configuration: many user, private ground stations

VSAT
Very Small Aperture Terminal
Dish TV?
A type of LEO Satellite system that serves both home an business users
Dish: antenna
A box as an interface between computer system and antenna

Mobile phone systems
Wireless telephone service, such as cellular telephone (analog), cell phone (both), and PCS (digital), etc..

The limited ranges of frequencies
FCC divided the country into 728 Mobile Service Areas, or metropolitan area or market.
Each market is broken into cells.
Each cell has its own transmission tower and set of assignable channels.

System configuration
Cell: 0,5 mile in radius to 50 miles.
A low-power transmitter /receiver, somewhere in the districts or communities. mobile (in vehicle)
Mobile Units mobile (in vehicle), portable (hand held) identifier electronic serial number (32 bit) system identification number (15 bit) mobile identification number (34 bit) tele #

System configuration
Base Transceiver full duplex with mobile connects to MTSO (microwave or wire )
Mobile Telephone Switching Office: in charge of a group of cells perform switching functions coordinate backup collect data (billing) test and monitor connect to public switched network
Interferences between cells: low-power in each cell, the same frequency can be used elsewhere.

Operation logon
Base Receiver---Control the Conversation Channels
Exchange with MTSO (Roamer or not) SIN monitoring
Mobile check channels, power handling calls
MTSO for connecting handovers mobile moving from cell to cell
MTSO determine new signals
Three Generation
Mobile technologies can be classified into different generations
First Generation---FDMA(AMPS)
Second Generation---- TDMA CDMA (GSM PCS)
Third Generation---Integrated CDMA
AMPS (1ST )
Advanced mobile phone service
The oldest analog mobile telephone system
Popular in North America and 35 other countries
Frequency division multiplexing technology
Cellular version of plain old telephone system (POTS)
Frequency allocation mobile to base (824-849 MHz) base to mobile (869-894 MHz)
12.5 MHz per operator
30 kHz per channel
416 channels per operator (21 control+ 395 call channel)
10-15 frequency per phone
Dynamic allocation, frequency reuse

GSM (1ST AND 2ND )
Global System for Mobile Comm.
Similar to AMPS, one type of 2nd generation
Europe
Differences: Subscriber Identity Module, encrypted transmission
Frequency allocation mobile to base (890-915 MHz) base to mobile (935-960 MHz)
200 kHz per channel data rate 270.833 kbps, faster
124 channels
8 conversations/channel (TDMA)

PCS (2ND AND 3RD )
Personal Communications Systems
One type of 2nd generation
Broadband: text, digitized voice, video, and multimedia packet-based transmission

Technologies:
Time division multiple access (TDMA): divide the available user channels by time, giving each transmitting mobile telephone a brief turn to transmit.
Code division multiple access (CDMA): spread spectrum technology
Hybrid telephones: concurrent use of analog( AMPS) and digital (PCS), because of moving around.
3RD
W-CDMA
Wide-band Code Division Multiple Access
CDMA-2000
Features;
Superior voice quality
Up to 2M bps, always digital broadband
WAP:
Wireless Application Protocol
3nd Generation
Capable of transmitting digital data between a mobile phone and an ISP.
WAP allows wireless devices such as mobile telephones, PDAs, pagers, and two-way radios to access the Internet.
WAP is designed to work with small screens and with limited interactive controls.
WAP incorporates Wireless Markup Language (WML) which is used to specify the format and presentation of text on the screen.

CDPD
Cellular Digital Packet Data
A specification for supporting wireless access to the Internet and other public packet-switched networks.
Slow speed: 19.2 Kbps
Advantages:
Stealing unused time from mobile telephone frequencies
Encryption
Broadcasting
Example: emergency vehicles to assist police, firefighters.
Pagers
Typically one-way communication service that uses ground-based and sometimes satellite-based systems (roaming).
Some systems are two-way.

SMS: short message services
Some systems can transmit small text messages.
E.g., Restaurant
Infrared Transmissions
Special radio transmissions that use a focused ray of light in the infrared frequency range.
Very common with remote control devices, but can also be used for device-to-device transfers, such as PDA to computer.
Will infrared last?
Same room, short distance
Bluetooth
Low-power, short-range radio frequency specification
Range from 10 cm to 10 m,100 m by increasing power.
Can transmit through solid, non-metal objects.
Point-to-multipoint voice and data transfer.
A wide range of computing and telecommunication devices phones and pagers, modems, LAN access devices, headsets, notebooks, desktop computers, and PDAs

Broadband Wireless Systems
Delivers digital data, video, Internet access into homes and businesses.
Designed to bypass the local loop telephone line.
Transmits voice, data and video over high frequency radio signals in full-duplex mode.
Two basic technologies:
Multichannel multipoint distribution service (MMDS) -;around 2.5 GHz, 30-35 miles, lower speed (512K-10M)
Local multipoint distribution system (LMDS) -;28 GHz -; 30 GHz, but only a few miles, higher speed (45M)

Media Selection
Cost -; Initial cost, ROI, maintain/support
Speed -;transfer speed, propagation speed
Distance and expandability
Environment -; Noise level
Security -; Wiretap possible? encryptions