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The report will look at satellite broadband access technology, concentrating on the principle of satellite broadband, different access systems, applications and advantages and disadvantages of different systems. The report also investigate the limitations of the satellite broadband and what actually done to overcome the problems, some of satellite broadband applications also discussed. The spread of broadband for both personal and business use is driving big demand for services and applications that are bandwidth hungry, especially for areas with little or nonexistent. But service providers need to work hard to overcome some of Satellite Broadband limitations like, latency need to improved, increasing capacity and cost. The satellite broadband market will, however, continue to face stiff competition from terrestrial players in the years to come.
Satellite communications has several advantages such as flexibility, broadband capability, global coverage, bandwidth on demand and multicast. It is a good way of providing broadband Internet access for individual and business in locations with poor or nonexistent
terrestrial infrastructure. The use of satellite communications system is a fact of everyday life and play important part of telecommunications systems, carrying large amount of data telephone traffic and television signal. The recent internet growth has resulted in a new generation of applications with higher throughput requirements and communication demands, satellite communication can be optimized such new demands.
Internet Satellite uses a Radio Frequency satellite link to provide users with broadband internet access. Internet Satellite use a Satellite to transmit data and a ground dish and
receiver to receive the data. This can be done with one-way system, or two-way system. In both systems users required to an outdoor dish and receiver.
There are a number of limitations that can affect satellite broadband, signal latency which can effect applications which require a user input with real time, like online games or remote surgery, and severe weather condition. Satellite broadband also require open sky between the satellite and ground dish, because the signal may experience interference from objects such as building, trees and hills. Satellite Broadband users require to have an outdoor Satellite dish and as well as indoor receiver, which both cost money.
Broadband Satellite provides high speed, always on internet connection and access for internet users in rule areas with no or poor terrestrial infrastructure. It integrated with direct to the home TV equipment and works well for broadcast oriented data traffic. Broadband Satellite can be use for many applications like high speed internet access, multimedia and gaming, video on demand, VPNs and VoIP.
Broadband Satellite technology uses a RF satellite link to provide subscribers with broadband Internet access. Early system is one-way system, which can provide of up to 400 kbps download, and for upload it uses 56 kbps analog modem. New system is two-way system, which expected to perform at 2 Mbps download and 500 kbps upload.
2.1 One-way access system
In 1-way system the broadband traffic can move only in one way. Subscribers able to download and receive internet data via the Satellite dish with fast speed up to 400kps. For upload users can use dial up using an analogue modem. The system is suitable for most users applications such as web browsing and downloading music and videos.
Figure 1: One way Satellite Broadband (Ref. Xilinx.com)
2.2 Two-way access system
The new system is 2-way satellite broadband, in which subscribers can be able to download and upload through the Satellite with high speed up to 2 Mbps, unlike one-way system. The system is suitable for most normal applications such as web browsing and downloading music and videos, also suitable for video conferencing.
Figure 2: Two-way Satellite Broadband (Ref. Xilinx.com)
3.1 Signal latency
Latency is the delay of the signal traveling from the sender to its destination, in 1-way communications, is the time when signal broadcasted, and the time it arrives to its destination. Satellite communications suffer from this latency, because signal have to travel out into space and back to Earth again. This delay can effect some applications which need a real time input, application like online games and video conferencing. Also the delay can effect interactive applications, such as VoIP and video conferencing, or other person to person communication. To solve the delay in signal in satellite communications TCP acceleration can be used to shorten the round trip time from the satellite down to earth. This technology features are being used in the modern satellite Internet services.
3.2 Rain fade
Another problem effect Satellite communications are the moisture in the air, rain and the snow. So they effect the signal between ground stations and the satellite. Lower frequency 'L' and 'C' bands are less effected than the higher frequency 'Ku' and 'Ka' band, which can be very bad. So for this reason satellite Internet services in tropical areas which have heavy rain, band L and C can be use. On the other hand, satellite communications on the Ka band can use different technologies like using bigger rain margins, reducing bit rate and adaptive uplink power control. Small dishes will reduce the rain margins and increase satellite downlink power as well as the cost. Large antenna dishes (3.7m to 13m) diameter can be used to obtain large rain margins and to decrease downlink power which reduce the cost per bit.
3.3 Line of sight
For a satellite system to work correctly a clear line of sight is needed between the satellite and the dish on the ground. The signal is effected by trees, buildings and can be absorbed and scattered along the way from the satellite to the dish. Most satellite system operate above frequency 2 GHz and can be effected by small obstructions. So dish installation need a good planning, specially if we install them in winter because trees grow in summer and spring.
3.4 Fresnel Zone
When signal travels between any two satellite dishes, does not travel in straight line, it propagate away from the dish and then become narrow when getting closer to the other dish. This is called Fresnel Zone, and it does affect the use of satellite dishes in places where there is not a clear line of sight for signal reception. A clear direct line of sight is needed for signal to travel through the space from the satellite to the earth, and also the signal should be clear for the Fresnel Zone area, which can be some time several meters bigger than the ground satellite dish.
Figure 3: The Fresnel zone is partially blocked (Ref: vias.org)
Satellite has become a household word today as many of its applications have touched the life of everyone. Satellites have been lunched for a variety of application like communication, navigation, weather forecasting, and earth observation, scientific and military services. The application areas of communication satellites mainly include television, telephony, data communication services, internet and multimedia.
4.1.0 High speed internet access
Satellite broadband provide high speed Internet access service, always on Internet connection for uses and businesses in remote or rural areas in which traditional high speed Internet access methods, DSL, cable, are not possible.
4.1.1 Satellite Broadband on Trains
Internet play a very important part of our every day life, users need internet access everywhere they go, on the train, plane and buses. The number of internet users on the move is growing fast, the demands of broadband access on the move is growing as well. At the mean time internet providers working hard to cover these demands, and provide a broadband access for users any where. One of these demands internet access on high speed passengerâ€™s trains. Some of the trains have a Wi-Fi access to passengers, but now train companies offer a satellite broadband on trains, which is delivered through a satellite earth antennas installed on the of the trains. This antennas will provide a faster internet access and reliable broadband connection for passengers. Hot spots are installed inside the trains to provide service access to userâ€™s terminals and they enable them to surf the net, access their emails, and so on.
4.1.2 In-Flight Internet
Satellite Broadband also used in-flight broadband Internet access, as the first commercial
flight to have this technology was launched by Lufthansa. Implementation of this service has continued and more airlines have begun offering the service, and many more airlines will take this service on board in the coming years. As this technology continues to have widespread implementation, more and more people will begin to utilize its service.
New technologies of communication is used with the current system in order to overcome problems that associated with satellite communication, such as signal delay, which causes problems for real time Internet applications due to the propagation delay of the satellite link, also the new methods can help to reduce the in-flight Internet usage cost.
Aeronautical ad hoc Network (AANET) is one of the new methods than being used. It is ad hoc network implemented between aircrafts in the sky, it will allow aircraft to share their cached data, from the satellite or the ground, and Internet access, which will reduce implementation cost and also reduce the in-flight Internet usage cost.
In AANET technology, an aircraft can download and cached data from the Internet, which can be done through satellite or directly from the ground. Then the cached data can be shared with other aircrafts in the sky which use ad hoc network.
AANET technology system requires less infrastructure and cost compare with normal methods of satellite internet systems, so AANET can be implemented and put into use faster. Any changes in AANETâ€™s system structure can be done in AANET system hardware or software which inside the aircraft, and this also can reduce system cost. AANET also reduce signal delay and it has high data rate and reduce satellite traffic load.
4.2 Voice over IP (VoIP) over Satellite
The developments of Voice over IP technology in which users can make and receive phone calls as they would do over the public switched telephone network (PSTN). VoIP provide low cost calls over existing data network, especially for business in remote locations where satellite communication is only option.
Due to the delay of satellite signal, VoIP is not a perfect technology, so call quality may vary but with the development of the VoIP and the technology over the coming yearâ€™s things will get butter and butter.
4.3 Multimedia and online gaming
Broadband Satellite Multimedia is one of the services that provided by satellite systems which needed a high speed broadband internet access in order to provide a good quality interactive multimedia communications to users, which is covering large market.
Online gaming has become a very popular in these modern days among almost all generations. As the technology advanced, online games become more sophisticated and the demand for faster internet connection. Online games become more interactive, so it need a fast internet connection, broadband internet is minimum requirement, as game producer recommend. Satellite Broadband able to provide this fast internet connection for those users in remote and rural areas, in which traditional broadband connection is not possible.
4.4 Virtual Private networks (VPNs)
This is a technology that is constantly growing and gaining interest among big companies, business and government organisations that use the internet to provide secure connection for both private and public communications. VPNs can provide secure connection between head office and other remote offices and employee residences. Speed is a very key factor in modern communication, VPNs can provide a high speed connection which is not available with traditional dialup. Also offices in remote locations or in rural area, where DSL and Cable Internet are not possible to clear reach them, VPNs can the only solution to connect them with rest of the organisation with reasonable cost. VPNs with two-way satellite Internet service can provide fast and reliable connection and is suitable web browsing, email, and most other common Internet applications.
There are a large number of opportunities for satellite in present and future telecommunication systems. The recent internet growth has resulted in a new generation of applications with higher throughput requirements and communication demands, satellite network is being developed to provide interactive, high speed communication and internet connection and it can be optimized such new demands. Satellite Internet Access is a growing segment of the larger Broadband Access market, is considered a small market compared to DSL and Cable Access, but still significant and it can be an efficient and cost effective. The market is driven by demand for high-speed internet in rural areas with no or poor terrestrial infrastructure, like rural areas, aeroplanes, fast trains and moving cars, also decreasing cost for equipment and standardization for increased vendor interoperability. But service providers still need to work hard to overcome some of Satellite Broadband limitation like, latency need to improved, increasing capacity and line of sight issues. Satellite broadband internet market is continuously growing and expected to be rolled out more rapidly in coming years, but it will continue to face hard competition from traditional broadband internet in the coming future.