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Satellite NetworksSatellite Networks

Shafaque Mahmood (07-02)Shafaque Mahmood (07-02)

Alia Ashraf (07-19)Alia Ashraf (07-19)

Saima Asghar (07-20)Saima Asghar (07-20)


Contents Contents

SatelliteSatellite Orbits Orbits Frequency bandsFrequency bands Satellite applications and workingSatellite applications and working Types Types Mechanics and LimitationsMechanics and Limitations


Shafaque MahmoodShafaque Mahmood


What is a satellite?What is a satellite?

A satellite is basically any object that A satellite is basically any object that revolves around a planet in a circular revolves around a planet in a circular or elliptical path. or elliptical path.


Orbits Orbits

The path a satellite follows is an The path a satellite follows is an orbitorbit. .

There are three basic orbitsThere are three basic orbits

1.1. Geostationary Earth Orbit (GEO)Geostationary Earth Orbit (GEO)

2.2. Low Earth Orbit (LEO)Low Earth Orbit (LEO)

3.3. Medium Earth Orbit (MEO)Medium Earth Orbit (MEO)


Geostationary Earth 0rbit (GEO)Geostationary Earth 0rbit (GEO)


Geostationary Earth Orbit (GEO)Geostationary Earth Orbit (GEO)

GEO satellites orbit the earth directly GEO satellites orbit the earth directly over the equator, approximately 35 over the equator, approximately 35 400 km (22 000 miles) up. 400 km (22 000 miles) up.

Take 24 hours to make a complete Take 24 hours to make a complete trip around the earthtrip around the earth

There latitude stays at zero and its There latitude stays at zero and its longitude remains constant.longitude remains constant.


GEO (cont)GEO (cont)

A single geostationary satellite will A single geostationary satellite will provide coverage over about 40 provide coverage over about 40 percent of the planet. percent of the planet.

Used for communications and Used for communications and weather-observation. weather-observation.

Service life expectancy of a Service life expectancy of a geostationary satellite is ten to geostationary satellite is ten to fifteen years.fifteen years.


Low Earth Orbit (LEO)Low Earth Orbit (LEO)


LEOLEO

Low Earth Orbit (LEO) refers to a satellite Low Earth Orbit (LEO) refers to a satellite which orbits the earth at altitudes between which orbits the earth at altitudes between (very roughly) 200 miles and 930 miles.(very roughly) 200 miles and 930 miles.

Move with the speed of approximately Move with the speed of approximately 17,000 miles per hour.17,000 miles per hour.

Because of this, LEO satellites can orbit Because of this, LEO satellites can orbit the planet in as little as 90 minutes.the planet in as little as 90 minutes.


LEO (cont)LEO (cont)

LEO satellite systems require several LEO satellite systems require several dozen satellites to provide coverage of the dozen satellites to provide coverage of the entire planet.entire planet.

LEO satellites are used for applications LEO satellites are used for applications where a short where a short Round Trip Time (RTT)Round Trip Time (RTT) is is very important, such as very important, such as Mobile Satellite Services (MSS)Mobile Satellite Services (MSS).

LEO satellites have a typical service life LEO satellites have a typical service life expectancy of five to seven years.expectancy of five to seven years.


Medium Earth Orbit (MEO)Medium Earth Orbit (MEO)


MEOMEO

A medium earth orbit (MEO) satellite is A medium earth orbit (MEO) satellite is one with an orbit within the range from a one with an orbit within the range from a few hundred miles to a few thousand miles few hundred miles to a few thousand miles above the earth's surface. above the earth's surface.

Satellites of this type orbit higher than LEO Satellites of this type orbit higher than LEO satellites, but lower than geostationary satellites, but lower than geostationary satellites. satellites.

The orbital periods of MEO satellites range The orbital periods of MEO satellites range from about two to 12 hours. from about two to 12 hours.


MEO (Cont)MEO (Cont)

A fleet of several MEO satellites, with A fleet of several MEO satellites, with orbits properly coordinated can provide orbits properly coordinated can provide global wireless communication coverage.global wireless communication coverage.

Because MEO satellites are closer to the Because MEO satellites are closer to the earth than geostationary satellites, earth-earth than geostationary satellites, earth-based transmitters with relatively low based transmitters with relatively low power and modest-sized antennas can power and modest-sized antennas can access the system.access the system.


Frequency BandsFrequency Bands

Letter designation for Letter designation for satellite frequency satellite frequency bandband

Frequency RangeFrequency Range

GHzGHz

LL 1-21-2

SS 2-42-4

CC 4-84-8

XX 8-128-12

(8-12.5 in North America)(8-12.5 in North America)

KuKu 12-1812-18

(12.5-18 in North America)(12.5-18 in North America)

KaKa 27-4027-40


C-BandC-Band

C-band is useful for many satellite C-band is useful for many satellite services, particularly TV distribution services, particularly TV distribution to cable TV systems and TV to cable TV systems and TV broadcast stations.broadcast stations.

Frequencies are not attenuated (or Frequencies are not attenuated (or subject to interference) by rain as subject to interference) by rain as much as Ku band, so C-band links are much as Ku band, so C-band links are extremely reliable extremely reliable


Ku-BandKu-Band

Ku-Band is used for providing satellite Ku-Band is used for providing satellite broadband services to small dishes (1 broadband services to small dishes (1 meter or less in diameter) and two-way meter or less in diameter) and two-way data communications.data communications.

Any video, data or voice service can be Any video, data or voice service can be provided at Ku band, and there are many provided at Ku band, and there are many satellites that provide Ku-band coverage in satellites that provide Ku-band coverage in the US and elsewhere.the US and elsewhere.

Reliability is satisfactory because of rain Reliability is satisfactory because of rain fadefade


Ka-BandKa-Band

Ka-band is the newest satellite Ka-band is the newest satellite broadcast band.broadcast band.

Ranging from 27 GHz to 40 GHz.Ranging from 27 GHz to 40 GHz. Ka-band is used by Wildblue and Ka-band is used by Wildblue and

DIRECTV.DIRECTV. Wildblue uses Ka-band for delivering Wildblue uses Ka-band for delivering

of satellite broadband and DIRECTV of satellite broadband and DIRECTV uses Ka-band to supplement their uses Ka-band to supplement their existing Ku band channel capacity.existing Ku band channel capacity.


Alia AshrafAlia Ashraf


Satellite Application TypesSatellite Application Types

• Broadcast and Multicast of Digital Content

• Voice and Telephony Networks• Data Communications and the Internet• Mobile and Personal Communications


Satellite ApplicationSatellite Application


Satellite components:Satellite components:

Two-way satellite consists of: Two-way satellite consists of: • Approximately a two-foot by three-foot Approximately a two-foot by three-foot

dish dish • Two modems (uplink and downlink) Two modems (uplink and downlink) • Coaxial cables between dish and Coaxial cables between dish and

modem modem


How satellite worksHow satellite works

Working of satellite consist on two Working of satellite consist on two parts:parts:• Earth stationEarth station• TransponderTransponder


How do Satellites WorkHow do Satellites Work Two Stations on Earth want to Two Stations on Earth want to

communicate through radio broadcast but communicate through radio broadcast but are too far away to use conventional are too far away to use conventional means.means.

The two stations can use a satellite as a The two stations can use a satellite as a relay station for their communicationrelay station for their communication

One One Earth Station Earth Station sends a transmission sends a transmission to the satellite. This is called a to the satellite. This is called a UplinkUplink..

The satellite The satellite TransponderTransponder converts the converts the signal and sends it down to the second signal and sends it down to the second earth station. This is called a earth station. This is called a DownlinkDownlink..


How do Satellites WorkHow do Satellites Work



Internet connection: Internet connection: The ISP's routers connect to proxy The ISP's routers connect to proxy

servers. servers. These are then connected to a DVB These are then connected to a DVB

encapsulator which is then connected to encapsulator which is then connected to a DVB-S modem. a DVB-S modem.



Theory of operationTheory of operation• Remote sites use the proxy server at the Remote sites use the proxy server at the

earth stationearth station• which makes sure no user exceeds their which makes sure no user exceeds their

allotted bandwidth or monthly traffic allotted bandwidth or monthly traffic limits.limits.


Satellite internet sevicesSatellite internet sevices MediumMedium

• AirAir LicenseLicense

• ITUITU Maximum Maximum download rate rate

• 1gbps1gbps Maximum Maximum upload rate rate

• 10Mbps10Mbps Latency

• 500ms500ms Frequency bands

• L, C, Ku, KaL, C, Ku, Ka


How does satellite internet work How does satellite internet work

A satellite connection as a high-A satellite connection as a high-speed digital link between a speed digital link between a customers location and Internet customers location and Internet backbone.backbone.

The data travels from the satellite The data travels from the satellite equipment at the customers location equipment at the customers location to the satellite, and then to the to the satellite, and then to the teleport for routing to the Internet.teleport for routing to the Internet.


How does Satellites internet WorksHow does Satellites internet Works


How does satellite internet workHow does satellite internet work

Spoofing makes the service capable of Spoofing makes the service capable of very high speeds.very high speeds.

What is spoofing?What is spoofing?• The entire Internet is based on TCP/IPThe entire Internet is based on TCP/IP• TCP manages and controls transmissions using TCP manages and controls transmissions using

IP IP • TCP sends data and looks for TCP sends data and looks for

acknowledgments.acknowledgments.• If the acknowledgments are not received, TCP If the acknowledgments are not received, TCP

resends the packets and slows down its resends the packets and slows down its transmission speed for future data.transmission speed for future data.

• Acknowledge may delay due to long trip and Acknowledge may delay due to long trip and slowdown the speed. slowdown the speed.


How does satellite internet workHow does satellite internet work

Spoofing:Spoofing:• Spoofing using NOC equipment that Spoofing using NOC equipment that

causes TCP acknowledgments to be causes TCP acknowledgments to be returned to the sender very quickly.returned to the sender very quickly.

• spoofing acknowledging the packets spoofing acknowledging the packets instantly, at the same time as it instantly, at the same time as it forwards the packets to the remote site.forwards the packets to the remote site.

• TCP sees rapid acknowledgments and TCP sees rapid acknowledgments and increase its speed quickly.increase its speed quickly.


Saima AsgharSaima Asghar


Types of Satellites Types of Satellites

Weather satellitesWeather satellites help scientists study forecasts and help scientists study forecasts and

weather patterns. Most weather weather patterns. Most weather satellites orbit on the polar orbit. satellites orbit on the polar orbit.


Communication satelliteCommunication satellite

This kind of satellite receives This kind of satellite receives messages and sends them back to messages and sends them back to another place. They do this with another place. They do this with thousands of calls all at the same thousands of calls all at the same time. These machines never rest. time. These machines never rest. Cell phones, satellite television Cell phones, satellite television systems, and governments use this systems, and governments use this type of satellite. type of satellite.


Navigation satelliteNavigation satellite

Navigation satellites are relied upon Navigation satellites are relied upon by aircraft and ships to tell them by aircraft and ships to tell them where they are located. Global where they are located. Global positioning systems (GPS) use this positioning systems (GPS) use this type of satellite too. type of satellite too.


Earth observation satellitesEarth observation satellites

Earth observing satellites help to Earth observing satellites help to keep track of the weather and the keep track of the weather and the environment. They are also used for environment. They are also used for mapping .mapping .

The satellites take photos of the The satellites take photos of the earth which can be applied to maps. earth which can be applied to maps.


Scientific SatellitesScientific Satellites

Observing the earth for scientific Observing the earth for scientific purposes is also very good possible purposes is also very good possible with satellites. Making maps with low with satellites. Making maps with low polar orbits satellites for instance, polar orbits satellites for instance, but also measuring the exact shape but also measuring the exact shape of the earth, geological research, etc of the earth, geological research, etc can all benefit greatly from scientific can all benefit greatly from scientific satellites.satellites.


Military satelliteMilitary satellite

They are specially designed and used They are specially designed and used for military purposes. Some military for military purposes. Some military satellites are called spy satellites. satellites are called spy satellites. They might be used to find out about They might be used to find out about missile launches, the courses of ships missile launches, the courses of ships at sea, and to track the movement of at sea, and to track the movement of military equipment.military equipment.


Mechanics and limitations Mechanics and limitations of satellite of satellite

communication.communication.

Latency is the delay between requesting Latency is the delay between requesting data and the receipt of a response, or in data and the receipt of a response, or in

the case of one-way communication, the case of one-way communication, between the actual moment of a signal's between the actual moment of a signal's broadcast and the time received at its broadcast and the time received at its

destination .destination .


. Compared to ground-based . Compared to ground-based communication, all geostationary communication, all geostationary satellite communications experience satellite communications experience high latency due to the signal having high latency due to the signal having to travel to an altitude of 35,786 km to travel to an altitude of 35,786 km (22,236 mi) above sea level (from (22,236 mi) above sea level (from the equator) out into space to a the equator) out into space to a satellite in geostationary orbit and satellite in geostationary orbit and back to Earth again. back to Earth again.


Rain fadeRain fade

Satellite communications are Satellite communications are affected by moisture and various affected by moisture and various forms of precipitation (such as rain or forms of precipitation (such as rain or snow) in the signal path between end snow) in the signal path between end users or ground stations and the users or ground stations and the satellite being utilized. satellite being utilized.


Line of sightLine of sight

Typically a completely clear line Typically a completely clear line of sight between the dish and of sight between the dish and the satellite is required for the the satellite is required for the system to work. In addition to system to work. In addition to the signal being susceptible to the signal being susceptible to absorption and scattering by absorption and scattering by moisture, the signal is similarly moisture, the signal is similarly impacted by the presence of impacted by the presence of trees and other vegetation in the trees and other vegetation in the path of the signalpath of the signal . .


Fresnel zoneFresnel zone

As the signal propagates away from As the signal propagates away from the transmitting dish, it widens the transmitting dish, it widens towards the centerpoint between the towards the centerpoint between the two dishes and then narrows again two dishes and then narrows again as it approaches the receiving dish. as it approaches the receiving dish. This is known as the fresnel zone, This is known as the fresnel zone, and limits the usefulness of satellite and limits the usefulness of satellite dishes in locations where there is dishes in locations where there is extremely limited open sky for signal extremely limited open sky for signal reception. reception.


Efficiency increasesEfficiency increases

Reducing satellite latencyReducing satellite latency

Special IP stacks and proxies can Special IP stacks and proxies can reduce latency through lessening the reduce latency through lessening the number of roundtrips, or simplifying number of roundtrips, or simplifying and reducing the length of protocol and reducing the length of protocol headers. These types of technologies headers. These types of technologies are generally referred to as TCP are generally referred to as TCP acceleration, HTTP pre-fetching and acceleration, HTTP pre-fetching and DNS caching.DNS caching.


Elimination of advertising Elimination of advertising materialsmaterials

The use of ad-blocking software such as The use of ad-blocking software such as Adblock for Firefox is exceptionally Adblock for Firefox is exceptionally beneficial for satellite Internet, as most beneficial for satellite Internet, as most Internet advertising websites use cache Internet advertising websites use cache busting in order to render the browser and busting in order to render the browser and ISP's cache useless, by displaying ISP's cache useless, by displaying advertisements (for the purpose of advertisements (for the purpose of maximizing the number of ad views seen maximizing the number of ad views seen by the affiliate marketing company's by the affiliate marketing company's server).server).


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