What does VSAT stand for?
VSAT is short for Very Small Aperture Terminal
What is VSAT?
VSAT is a small satellite dish that is capable of both receiving and sending satellite signals. VSAT systems can be designed to serve both broadcast and interactive applications whether data, voice or video, which are traditionally served by terrestrial/mobile lines. VSAT offers highly reliable, flexible support of integrated multimedia communications. Compared to alternative technologies, VSAT offers customers the following features:
- Star network topology - offers end-to-end shared hub services for network requirements that cannot economically support a dedicated hub and operated by experienced staff to ensure optimum service levels.
- Full mesh connectivity - provides a hubless network using only one satellite hop, offers lower delay and better response times. Smaller networks can be implemented at lower costs than traditional hub-based systems.
- Bandwidth-on-Demand - architecture automatically allocates a pool of bandwidth to meet customer requirements of any site. The customer can move or add host computers and PABX's without having to re-engineer or re-size the network. Servers may be centralized or distributed. The bandwidth automatically "follows" the new traffic patterns.
- Scalability of network capacity - The aggregate network capacity can be increase from time to time as the number of sites and volume per site grows.
- Modularity and open system architecture - supports modular and open system architecture. The customer can expand the number of interfaces at the indoor unit as he requires.
- Economics of statistical multiplexing - Multiple applications share the same bandwidth. The customer uses and pays for less total bandwidth than with the more traditional multiple dedicated network approaches.
- Network Management and Control - operating on global standards and operational 24 hours a day, 7 days a week.
- Cost effective solution - provides cost-effective communication solutions with high level functionality and performance since the pricing is distance independent. It offers a competitive alternative even for countries, which have a high degree of communication infrastructure.
Why VSAT?
The dish is small, easily transportable and installation lead-time is much shorter if compared to terrestrial links. In addition, VSAT network allows rapid, low-cost network re-configuration and expansion to meet new or unexpected business requirements. Cost effective transmission and network operations are made possible by use of the C-band satellite frequency and frequency times division multiple access (FTDMA), Frequency division multiple access (FDMA) or Time division multiple access (TDMA) transmission techniques. VSAT offers a wide of protocols and features, providing extraordinary flexibility and virtually unlimited expansion capabilities. In addition, VSAT network is typically engineered to achieve a minimum of 99.7% end-to-end availability for all locations.
How does a VSAT network look?
VSAT networks come in various shapes and sizes ranging from a star topology system with an operator's shared hub serving many thousands VSATs located at the customers' site. Mesh systems, where individual VSATs can send and receive traffic to/from other VSATs, have traditionally been somewhat smaller in size than star systems.
What are the applications of VSAT?
VSAT is an ideal solution that provides communications support for a wide range of applications:
- Point-of-sales transaction
- Order-Entry Billing
- Inventory Control
- Financial Management
- Data processing
- Reservation System
- Telemetry & Data Collection
- News Wire Services
- Virtual Private Networks
- Distance Education
- High Speed Internet Access
Who should subscribe to VSAT?
VSAT presents new alternatives to the problems of conventional fixed terrestrial telecommunication beyond PSTN areas. VSAT can also help to design tailored communication business to the following sectors:
- Oil and Energy
- Finance and banking
- Construction Companies
- Government Agencies
- Manufacturing
- Mining and explorations
- News agency
- Shipping and freight handling•
- Travel and tourism
- Agricultural companies
What are the components in a VSAT site?
A typical VSAT site consists of a parabolic-shaped antenna mounted on the roof of a building, connected by a cable to a chassis inside the building. The size of the indoor unit is similar to that of a laptop
What does the VSAT unit contain?
A typical VSAT unit contains a modem for translating satellite transmissions into data and vice versa and terrestrial interfaces for connecting customer equipment.
What are the benefits of VSAT to the customers?
The benefits are:
i. Across border - Wide area coverage. Satellite communication offers borderless communication within the satellite coverage area. Reachable to remote areas with digital transmission
ii. Rapid deployment for new sites - Rapid commissioning of new sites within an existing network
iii. Cost effective - The pricing is distance independent. No matter how far your location is, the pricing is still the same.
iv. Flexibility and efficiency - Network configuration changes such as bandwidth, interfaces, data rates, etc. can be performed remotely from the central network management system.
v. Independent of terrestrial infrastructures - Worldwide deregulation of satellite communication services is fast becoming a fact. This allows worldwide implementation of truly private networks.
vi. Simplicity - quick deployment.
vii. Reliability and Availability - Satellite communication typically gives 99.7% availability.
viii. No local loop issues - VSAT is installed directly on the customer's site, no terrestrial backhaul costs, flexibility with increasing bandwidth, terrestrial link availability etc.
What is a satellite transponder?
A satellite transponder is a combination receiver, frequency converter, and transmitter package. It is physically part of a communications satellite. Communications satellites typically have 12 to 24 onboard transponders.
What are the typical VSAT network configurations?
VSAT networks can be arranged in point-to-point, star, mesh, star/mesh, and broadcast configurations. The preferred arrangement depends on the kind of information flow the network will service.
What is a point-to-point VSAT network?
TA point-to-point network allows two-way communications between two VSAT sites.
What is a star VSAT network?
A star network allows any number of VSAT sites to have two-way communication with a central hub.
What is a mesh VSAT network?
A mesh network allows two-way communications between any VSAT sites in a network. A central hub is not necessary. Each site communicates to another site with a single satellite hop.
What are the different VSAT transmission methods?
There are three basic VSAT transmission types: TDMA, time-division multiple access; DAMA, demand-assigned multiple access; and SCPC / MCPC, single/multiple channel per carrier.
What are the characteristics of a TDMA transmission type?
TDMA is a form of multiple access in which a single carrier is shared by many users. When signals from earth stations reach the satellite, they are processed in time segments without overlapping. TDMA is typically used in a packet switched environment when small or moderate amounts of data are to be transferred.
What are the characteristics of a DAMA transmission type?
The DAMA protocol is used to share bandwidth in a time division mode. Typically DAMA transmission is used in a packet-switched environment when large amounts of data are to be transferred. Is a highly efficient means of instantaneously assigning telephony channels in a transponder according to immediate traffic demands. DAMA is also applicable in a circuit-switched environment and is usually characterized by allowing each user a variable slot of time on a demand (or request) basis.
What are the characteristics of a SCPC / MCPC transmission type?
SCPC / MCPC systems use a dedicated satellite link between a few distinct locations. These links can support either a single telephone line or several telephone or data lines. Such links generally are permanently assigned with no carrier switching or rerouting over the satellite.
What is SCPC-DAMA transmission?
SCPC-DAMA systems provide a control network on top of an SCPC network. When a particular station wishes to make a telephone call, the control network is used to forward that request to a central processor that sets up a dedicated SCPC link between the two sites. When the call is finished, the link is taken down and the satellite resources can be used for a different call. SCPC-DAMA best supports applications in which there are few telephone lines per site and telephone calls are infrequent.
What is TDM-TDMA transmission?
TDM-TDMA networks are designed for interactive data applications. TDM-TDMA systems feature a large expensive hub that provides basic data communications to very inexpensive remote sites. The architecture supports many remote stations using a small amount of satellite bandwidth. Data rates supported at the remote sites are typically between 1.2 kbps and 9.6 kbps; however, this type of traffic has a very low average data rate. Each station may transmit bursts of 9.6 kbps data, but they generally average less than 100 bps. Typical applications are transactional in nature. Examples include credit card verifications, point-of-sale systems, SCADA systems, and inventory control.
What is TDMA-DAMA transmission?
TDMA-DAMA networks have the same demand assignment capability as SCPC-DAMA networks, but also have division multiplexing to reduce the need for multiple modems at each site. TDMA-DAMA networks allow many telephone calls to be placed simultaneously to different destinations through a single station.
What is FDMA transmission?
FDMA (Frequency Division Multiple Access) uses a single modem for all communication from a site and transmits for very short intervals and at higher data rates. FDMA uses multiple carriers within the same transponder within which each uplink has been assigned frequency slot and bandwidth. It is usually used in conjunction with frequency modulation.
What is the advantage of a TDMA-DAMA system?
TDMA-DAMA systems support many telephone lines with very little incremental cost. E1 or T1 interfaces can be provided for direct digital connections to PBXs or telephony switches. TDMA-DAMA systems are also flexible in supporting applications such as data, video conferencing, broadcast, and the like. In addition, TDMA networks are hub-less, which eliminates the high cost of a hub and a single point of failure within the network.
What applications do TDMA-DAMA networks best support?
TDMA-DAMA networks support applications with mesh connectivity and applications that require multiple services that are integrated into a single network such as telephony, low-to-high speed data imaging, fax, and interactive video conferencing.
