Vsat access control protocols

1. Department of Electronic and telecommunications Engineering
International Islamic University Chittagong
Submitted by,
Syed Mainul Islam
( ID: T-151020 )
Dept. of ETE, IIUC.
Submitted To,
Md. Razu Ahmed
( Associate Professor )
Dept. of ETE, IIUC.
1

2. VSAT technology is a telecommunication system based on wireless satellite
technology. The term VSAT stands for “Very Small Aperture Terminal”. VSAT
describes a small terminal that can be used for two-way communications via
satellite. VSAT networks offer value-added satellite-based services capable of
supporting the Internet, data, video, LAN, voice/fax communications, and can
provide powerful private and public network communication solutions. They are
becoming increasingly popular, as VSATs are a single, flexible communications
platform that can be installed quickly and cost efficiently to provide telecoms
solutions for consumers, governments and corporations.
A VSAT network consists of three components:
 A central hub
 A satellite
 A virtually unlimited number of VSAT user terminals.
2

3. The earth stations of a VSAT network communicate across the satellite by means of modulated
carriers. Depending on the network configuration, different types and numbers of carriers must
128 NETWORKING ASPECTS be routed simultaneously within the same satellite transponder.
Figure(1.1-1.3) illustrâtes diffèrent possible situations:
 with one-way networks, where the hub broadcasts a time division multiplex of data to many
receive-only VSATs, only one carrier is to be relayed by the satellite transponder. Accordingly,
there is no other carrier competing for satellite transponder access, and there is no need for any
multiple access protocol.
 with two-way star-shaped networks, carriers from VSATs and the hub station are competing to
access a satellite transponder.
 with two-way meshed networks, there is no hub station and the only carriers competing to
access a satellite transponder are those transmitted by the VSAT stations.
3

4. Fig-1.1: Multiple Access for One way networks
4

5. Fig-1.2: Multiple Access for Two way star shaped networks
5

6. Fig-1.3: Multiple Access for Two way meshed networks
6

7.  Frequency division multiple access (FDMA) means allocating a given sub band of overall
transponder bandwidth(B) to every carrier.
 Time division multiple access (TDMA) means allocating the overall bandwidth of the
transponder (B) to every carrier in sequence for a limited amount of time, called a time slot.
 Code division multiple access(CDMA)is a multiple access technique which does not consider
any frequency–time partition: carriers are allowed to be transmitted continuously while
occupying the full transponder bandwidth (B).
7

8. Fig-2: Basic Multiple Access Protocols
8

9.  The benefits of VSAT technology are being realized in many sectors, both private
and public. From banks to administrations, schools, hospitals and rural
telecommunications, VSATs are being seized upon to elevate economic,
educational, and health standards.
 VSAT technology it is two way communication via satellite that allows to service
providers offers fast and secure transmission.
 The main advantages of VSAT systems are their flexibility and ease of installation.
 The established terrestrial network is certain to expand its coverage progressively,
and in fixed configurations between large population centers it will provide the
most efficient means of communications.
 VSAT network can be secure against of the different five types of hacking by
securing the VSAT terminals and VSAT communication link.
9

10. 10