VSAT
Dr.Ir.Joko Suryana
Introduction
• Satellite Communication
is a technology of data transmission whether one-way data
broadcasting or two-way interactive using frequency
as a medium.
Consist of :
• Space Segment or Satellite ( eg. Measat, Intelsat, Inmarsat )
• Ground Segment or earth station which includes Antenna, Outdoor Unit,
Inter Facility Link, Indoor Unit and Customer Premises Equipment.
• VSAT
is a satellite-based communications service that offers flexible
and reliable communications solutions including Enterprise
Wide Networking with high reliability and a wide reach that
extend even to remote sites.
Why VSAT?
VSAT networks provides:
• Reliability in transmission of data (data, voice, video)
• Allocation of resources to different users (bandwidth,
amplification power)
• Fixed network solutions at reasonable price (eg. voice
channel at 3-15 cents/min.)
• Provide point-to-multipoint (broadcast), multipoint-topoint (data collection), point-to-point communications
and broadband multimedia services.
• Serviced in land area which are difficult to install
(remote locations ,water areas).
• An ability to have direct access to users and user
premises.
VSAT Characteristic and Advantage
• Reliability: reliable satellite transmission of data, voice and video between
an unlimited number of geographically dispersed sites or from these sites
to headquarters
• Flexibility: The VSAT networks offer enormous expansion capabilities; On
the other hand, VSATs offer unrestricted and unlimited reach. Additional
VSATs can be rapidly installed to support the network expansion to any
site, no matter however remote.
• Network Management: Network monitoring and control of the entire VSAT
network is much simpler than a network of leased lines, easily integrates
end-to-end monitoring and configuration control for all network
subsystems.
• A low mean-time to repair - few hours, compare to leased lines which
extends up to a few days. Essentially, lesser elements imply lower MTTR.
Uptime of up to 99.5 percent is achievable on a VSAT network. This is
significantly higher than the typical leased line uptime of approximately
80-85%.
VSAT Characteristic and Advantage
• Cost: VSAT network offers significant savings over 2-3 years
timeframe. The service charges depend on the bandwidth
which is allocated to the network in line with customer
requirements.
• Link Budgets: RF equipment would cater to the requirements
of the network topology and satellite modems in use. The link
Budget estimates the ground station and satellite EIRP
(Effective Isotropic Radiated Power) required. Calculations of
signal levels through the system to ensure the quality of
service should normally be done, prior to the establishment
of a satellite link.
VSAT Services
• Interactive real time application:
– Point of Sale/retail/Banking (eg. ATM)
– Corporate data
• Telephony
– Rural : individual subscribers
– Corporate Telephony
• Intranet, Internet and IP infrastructure
– Multimedia delivery (eg. video streaming)
– Interactive distance learning/ training
• Direct-to-home
– Broadband Internet access for consumers and businesses
Satellite Communication Concept
C Band – 6/4GHz
Ku Band -14/12GHz
Ka Band – 30/20GHz
Uplink
6 GHz
HPA
Downlink
4 GHz
LNA
Up Converter
Down Converter
Satellite Modem
Satellite Modem
CPE
CPE
PSTN
Transmitting Earth
Receiving Earth
Station
Station
PSTN
Note :
HPA – High Power Amplifier (Earth station equipment that amplifies the transmit RF signal. )
CPE – customer premises equipment ( eg. Telephone, PABX, Ethernet hub, host server, etc.)
VSAT Communication Concept
C Band – 6/4GHz
Ku Band -14/12GHz
Ka Band – 30/20GHz
Uplink
6 GHz
HPA
Downlink
4 GHz
LNA
Up Converter
Down Converter
Satellite Modem
Satellite Modem
CPE
CPE
PSTN
Transmitting Earth
Receiving Earth
Station
Station
PSTN
Hub System
VSAT Station Equipment
VSAT specification
Antenna diameter: 0.6m – 3.8m
Traffic Capacity : 9.6Kbps – 2Mbps
Frequency Bands : C-band (4-6Ghz),
Ku-Band (12-14Ghz),
Ka-Band (20-30Ghz)
Use of satellite : Geo-stationary satellite
(36,000km above equator)
Network: Point-to-point
Configuration
: Point-to-multipoint
Equipment List :
– Antenna;
– Outdoor Unit (High Power Amplifier (HPA), Low Noise Amplifier (LNA), SolidState Power Amplifier (SSPA))
– Indoor Unit (chassis)
Note :
• Antenna size is used to describe the ability of the antenna to amplify the
signal strength;
• Outdoor unit (ODU) is connected through a low-loss coaxial cable to the
indoor unit (IDU) called IFL (Interfacility Link).
Typical VSAT system
• Up- converters and High Powered
Amplifiers
(HPA)
• antenna
varies
- antenna size describe the
• Radio Frequency Terminal (RFT) is mounted on the antenna
used for converting and amplifyingability
the signal
of thebefore
antenna to amplify the signal
frame and interconnected to the feed-horn + Low Noise
transmitting to the feed-horn.
strength
Amplifiers (LNA) + down-converters.
• Extended C band, down converter
receives the
signal
• feed-horn
directs
transmitted power to
• LNAs – minimize signal noise. Noise temperature is parameter
at 4.5 to 4.8GHz and the up converter
converts
it to
antenna
dish or
collects the received power from
used to describe the performance of an LNA.
6.725 to 7.025GHz.
it.
VSAT ODU and ISU : Equipment
Outdoor Unit
Feed Assembly
Indoor Unit
Typical value for ODU ( VSAT )
Hub Antenna
Typical value for ODU ( Hub )
Network Components
Skystar 360E
Typical Hub Configuration
VSAT Budget
VSAT Topology
• STAR - the hub station controls and monitors can
communicates with a large number of dispersed VSATs.
Generally, the Data Terminal Equipment and 3 hub antenna is
in the range of 6-11m in diameter. Since all VSATs
communicate with the central hub station only, this network is
more suitable for centralized data applications.
• MESH - a group of VSATs communicate directly with any other
VSAT in the network without going through a central hub. A
hub station in a mesh network performs only the monitoring
and control functions. These networks are more suitable for
telephony applications.
• HYBRID Network - In practice usually using hybrid networks,
where a part of the network operates on a star topology while
some sites operate on a mesh topology, thereby accruing
benefits of both topologies.
VSAT Network Architectures
One Way
• One-Way – Receive Only
– High Bit-Rate DVB Compliant Outbound
– Inbound Return Channel via Dial-Up Modem
– Can be used with existing infrastructure
• Example: Harmonic’s CyberStreamTM
Baseband
Equipment
Satellite
DVB Modulator
LAN
DVB Receiver
RFT
IP Encapsulator
VSAT TVRO
Antenna
TCP/IP ACK’s NACK’s
Router
Internet
Modem/ISDN
Return
VSAT Network Architectures
Two-Way Star Topology
•
•
•
All VSATs Communicate via a Single Hub
Network is Independent of Existing Infrastructure
VSAT Antenna Size dependent upon Power and Gain of Hub Antenna
– Also Upon Inbound Bitrate, ODU Power and Satellite Footprint
•
•
Contention Based Access – Usually TDMA or FTDMA
Typical Ping Times Approximately 650-700ms
VSAT
VSAT
VSAT
Hub
VSAT
VSAT
VSAT
VSAT
VSAT
VSAT Network Architectures
Two-Way Mesh Topology
•
•
•
•
•
•
VSATs communicate directly with each other
Some systems require initial signaling via the Hub
Larger Antennas, Higher Power required at the VSAT
Smaller Antenna, Lower Power required at the Hub
Used extensively in Telephony Networks
Delay minimized on VSAT to VSAT Calls
VSAT
VSAT
VSAT
VSAT
VSAT
VSAT
VSAT Topology
What is VSAT Accessing Scheme?
The objective of VSAT networks:
- is to maximize the use of common satellite
and other resources amongst all VSAT sites.
The method:
- by optimizing the use of satellite capacity, and
spectrum utilization in a flexible and costeffective manner ( referred as satellite access
schemes.)
- or we can call as VSAT technology.
Type of VSAT technology
TDMA
Time-division
Multiple Access
VSAT
TECHNOLOGY
SCPC
Single-carrier
per Channel
PAMA
Pre-Assigned
Multiple
Access
FDMA
Frequency Division
Multiple Access
FDMA
DAMA
Demand
Assigned
Multiple
Access
CDMA
Code Division
Multiple
Access
TDMA (time-division multiple access)
• When numerous remote sites communicate with one
central hub, this design is similar to packet-switched
networks.
• Because of competition with one another for access
to the central hub, it restrict the maximum
bandwidth to most cases is about 19.2 kbps.
• all VSATs share satellite resource on a time-slot basis.
• Usually used in STAR topology as a transmission
technique.
• Offered to domestic needs.
TDMA (time-division multiple access)
Copyright Maxis
The VSAT Hub communicates with all dispersed VSATs (typically a 1.8-meter diameter parabolicshaped dish) on an outgoing channel of up to 512kbps based on the TDM scheme. The incoming or
return channel from the dispersed VSATs uses the TDMA channel technology that enables a large
number of the respective VSATs to share this single return channel. The incoming routes typically
operate at 128kbps, and can go up to a maximum bandwidth of 256kbps.
TDMA (time-division multiple access)
Copyright Maxis
Petrol stations, information providers, retail chains, financial institutions and any large
corporation that requires transfers of low to medium rate data applications between its
head office and, local and outstation branch offices. Example of Point of Sales (POS
transactions), Credit Card Verification, Reservations Systems
Financial and Banking applications (teller, loans, ATM) etc.
SCPC (single-carrier per channel)
• SCPC-based design provides a point-to-point
technology, making VSAT equivalent to
conventional leased lines.
• dedicated bandwidth of up to 2 Mbps
• Usually use in an international VSAT services
in Asia-Pacific.
SCPC (single-carrier per channel)
Copyright Maxis
In the Hub-to-Remote configuration, one end of the VSAT link (normally the customer's
HQ) is connected to the 11-meter VSAT Hub (Earth Station) via a terrestrial leased line. A
VSAT antenna at the remote end or the distant end (normally the branch office) of the
VSAT link is then interconnected to the VSAT hub via the satellite.
SCPC (single-carrier per channel)
Copyright Maxis
VSAT links with a Remote-to-Remote configuration bypass the VSAT Hub and has a
stand-alone VSAT antenna at both ends of the link. Typical VSAT antenna size ranges
from 1.8m to 2.4m.
FDMA (Frequency Division Multiple Access)
• oldest method for channel allocation
• the satellite channel bandwidth is broken into
frequency bands for different earth stations
• the earth stations must be carefully power-controlled
to prevent the microwave power spilling into the
bands for the other channels. Here, all VSATs share
the satellite resource on the frequency domain only.
3 type:
• PAMA (Pre-Assigned Multiple Access);
• DAMA (Demand Assigned Multiple Access); and
• CDMA (Code Division Multiple Access).
PAMA (Pre-Assigned Multiple Access);
• the VSATs are pre-allocated a designated
frequency. Equivalent of the terrestrial (land
based) leased line solutions.
• PAMA solutions use the satellite resources
constantly. Therefore, no call-up delay in the
interactive data applications or high traffic
volumes.
• PAMA connects high data traffic sites within
an organization.
DAMA (Demand Assigned Multiple Access);
• The network uses a pool of satellite channels, which are
available for use by any station in that network.
• On demand, a pair of available channels is assigned, so that a
call can be established. Once the call is completed, the
channels are returned to the pool for an assignment to
another call.
• Since the satellite resource is used only in pro-portion to the
active circuits and their holding times, this is ideally suited for
voice traffic and data traffic in batch mode.
• DAMA offers point-to-point voice, fax, data requirements and
supports video-conferencing. Satellite connections are
established and dropped only when traffic demands them.
CDMA (Code Division Multiple Access)
• Under this, a central network monitoring system allocates a
unique code to each of the VSATs. Enabling multiple VSATs to
transmit simultaneously and share a common frequency
band.
• The data signal is combined with a high bit rate code signal
which is independent of the data.
• Reception at the end of the link is accomplished by mixing the
incoming composite data/code signal with a locally generated
and correctly synchronized replica of the code.
• Since this network requires that the central network
management system co-ordinates code management and
clock synchronization of all remote VSATs, STAR topology is
the best one.
• Mainly used for interference rejection or for security reasons
in military systems.
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