Presented By:
Shafaque Mahmood
Alia Ashraf
Saima Asghar

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Satellite Networks
What is a satellite?
A satellite is basically any object that revolves around a planet in a circular or elliptical path.
Orbits
The path a satellite follows is an orbit.
There are three basic orbits
Geostationary Earth Orbit (GEO)
Low Earth Orbit (LEO)
Medium Earth Orbit (MEO)
Geostationary Earth 0rbit (GEO)
Geostationary Earth Orbit (GEO)
GEO satellites orbit the earth directly over the equator, approximately 35 400 km (22 000 miles) up.
Take 24 hours to make a complete trip around the earth
There latitude stays at zero and its longitude remains constant.
GEO (cont)
A single geostationary satellite will provide coverage over about 40 percent of the planet.
Used for communications and weather-observation.
Service life expectancy of a geostationary satellite is ten to fifteen years.
Low Earth Orbit (LEO)
LEO
Low Earth Orbit (LEO) refers to a satellite which orbits the earth at altitudes between (very roughly) 200 miles and 930 miles.
Move with the speed of approximately 17,000 miles per hour.
Because of this, LEO satellites can orbit the planet in as little as 90 minutes.
LEO (cont)
LEO satellite systems require several dozen satellites to provide coverage of the entire planet.
LEO satellites are used for applications where a short Round Trip Time (RTT) is very important, such as Mobile Satellite Services (MSS).
LEO satellites have a typical service life expectancy of five to seven years.
Medium Earth Orbit (MEO)
MEO
A medium earth orbit (MEO) satellite is one with an orbit within the range from a few hundred miles to a few thousand miles above the earth's surface.
Satellites of this type orbit higher than LEO satellites, but lower than geostationary satellites.
The orbital periods of MEO satellites range from about two to 12 hours.
MEO (Cont)
A fleet of several MEO satellites, with orbits properly coordinated can provide global wireless communication coverage.
Because MEO satellites are closer to the earth than geostationary satellites, earth-based transmitters with relatively low power and modest-sized antennas can access the system.
Frequency Bands
C-Band
C-band is useful for many satellite services, particularly TV distribution to cable TV systems and TV broadcast stations.
Frequencies are not attenuated (or subject to interference) by rain as much as Ku band, so C-band links are extremely reliable
Ku-Band
Ku-Band is used for providing satellite broadband services to small dishes (1 meter or less in diameter) and two-way data communications.
Any video, data or voice service can be provided at Ku band, and there are many satellites that provide Ku-band coverage in the US and elsewhere.
Reliability is satisfactory because of rain fade
Ka-Band
Ka-band is the newest satellite broadcast band.
Ranging from 27 GHz to 40 GHz.
Ka-band is used by Wildblue and DIRECTV.
Wildblue uses Ka-band for delivering of satellite broadband and DIRECTV uses Ka-band to supplement their existing Ku band channel capacity.
Satellite Application Types
Broadcast and Multicast of Digital Content
Voice and Telephony Networks
Data Communications and the Internet
Mobile and Personal Communications
Satellite Application
Satellite components:
Two-way satellite consists of:
Approximately a two-foot by three-foot dish
Two modems (uplink and downlink)
Coaxial cables between dish and modem
How satellite works
Working of satellite consist on two parts:
Earth station
Transponder
How do Satellites Work
Two Stations on Earth want to communicate through radio broadcast but are too far away to use conventional means.
The two stations can use a satellite as a relay station for their communication
One Earth Station sends a transmission to the satellite. This is called a Uplink.
The satellite Transponder converts the signal and sends it down to the second earth station. This is called a Downlink.
How do Satellites Work
How do Satellites Work
Internet connection:
The ISP's routers connect to proxy servers.
These are then connected to a DVB encapsulator which is then connected to a DVB-S modem.
How do Satellites Work
Theory of operation
Remote sites use the proxy server at the earth station
which makes sure no user exceeds their allotted bandwidth or monthly traffic limits.
Satellite internet sevices
Medium
Air
License
ITU
Maximum download rate
1gbps
Maximum upload rate
10Mbps
Latency
500ms
Frequency bands
L, C, Ku, Ka
How does satellite internet work
A satellite connection as a high-speed digital page link between a customers location and Internet backbone.
The data travels from the satellite equipment at the customers location to the satellite, and then to the teleport for routing to the Internet.
How does Satellites internet Works
How does satellite internet work
Spoofing makes the service capable of very high speeds.
What is spoofing?
The entire Internet is based on TCP/IP
TCP manages and controls transmissions using IP
TCP sends data and looks for acknowledgments.
If the acknowledgments are not received, TCP resends the packets and slows down its transmission speed for future data.
Acknowledge may delay due to long trip and slowdown the speed.
How does satellite internet work
Spoofing:
Spoofing using NOC equipment that causes TCP acknowledgments to be returned to the sender very quickly.
spoofing acknowledging the packets instantly, at the same time as it forwards the packets to the remote site.
TCP sees rapid acknowledgments and increase its speed quickly.
Types of Satellites
Weather satellites
help scientists study forecasts and weather patterns. Most weather satellites orbit on the polar orbit. 
Communication satellite
This kind of satellite receives messages and sends them back to another place. They do this with thousands of calls all at the same time. These machines never rest. Cell phones, satellite television systems, and governments use this type of satellite. 
Navigation satellite
Navigation satellites are relied upon by aircraft and ships to tell them where they are located. Global positioning systems (GPS) use this type of satellite too. 
Earth observation satellites
Earth observing satellites help to keep track of the weather and the environment.  They are also used for mapping .
The satellites take photos of the earth which can be applied to maps.
Scientific Satellites
Observing the earth for scientific purposes is also very good possible with satellites. Making maps with low polar orbits satellites for instance, but also measuring the exact shape of the earth, geological research, etc can all benefit greatly from scientific satellites.
Military satellite
They are specially designed and used for military purposes. Some military satellites are called spy satellites. They might be used to find out about missile launches, the courses of ships at sea, and to track the movement of military equipment.
Mechanics and limitations of satellite communication.
Latency is the delay between requesting data and the receipt of a response, or in the case of one-way communication, between the actual moment of a signal's broadcast and the time received at its destination .
. Compared to ground-based communication, all geostationary satellite communications experience high latency due to the signal having to travel to an altitude of 35,786 km (22,236 mi) above sea level (from the equator) out into space to a satellite in geostationary orbit and back to Earth again.
Rain fade
Satellite communications are affected by moisture and various forms of precipitation (such as rain or snow) in the signal path between end users or ground stations and the satellite being utilized.
Line of sight
Typically a completely clear line of sight between the dish and the satellite is required for the system to work. In addition to the signal being susceptible to absorption and scattering by moisture, the signal is similarly impacted by the presence of trees and other vegetation in the path of the signal .
Fresnel zone
As the signal propagates away from the transmitting dish, it widens towards the centerpoint between the two dishes and then narrows again as it approaches the receiving dish. This is known as the fresnel zone, and limits the usefulness of satellite dishes in locations where there is extremely limited open sky for signal reception.
Efficiency increases
Reducing satellite latency
Special IP stacks and proxies can reduce latency through lessening the number of roundtrips, or simplifying and reducing the length of protocol headers. These types of technologies are generally referred to as TCP acceleration, HTTP pre-fetching and DNS caching.
Elimination of advertising materials
The use of ad-blocking software such as Adblock for Firefox is exceptionally beneficial for satellite Internet, as most Internet advertising websites use cache busting in order to render the browser and ISP's cache useless, by displaying advertisements (for the purpose of maximizing the number of ad views seen by the affiliate marketing company's server).