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1. VSAT Basics
Presenter: Dave Rehbehn

2. What Is A VSAT
Very Small Aperture
Terminal
• Refers to the size of the antenna
reflector
• VSAT is generally .74 meter up to 2.4
meter
VSAT (remote station) consists of:
Outdoor Unit (ODU):
• Reflector
• Transceiver (BUC and LNB)
IFL Cable
• Coax cable to connect IDU to ODU
Indoor Unit (IDU)
• Ethernet interface to LAN

3. VSAT Access Technologies
SCPC
(Single Channel Per Carrier)
DVB-S2(TDM)/FD-TDMA
F1
F2
DVB-S2
Forward
FD-TDMA
Return
Circuit Based Access Scheme
Mesh Topology (point to point)
Dedicated Bandwidth
Well Suited To High Capacity Links
Packet Based Access Scheme
Star Topology (point to multipoint)
Shared Bandwidth
Well Suited To Last Mile IP Access
DVBS2/FD-TDMA VSATs
Are The Biggest Part Of
The Market

4. VSAT Are IP Devices
 Satellite Modem
 Receives DVB-S2/ACM Forward Channel
 Transmit FD-TDMA Return Channel
 IP Router
 Network/Port Address Translation
 DHCP Server/Relay
 DNS Caching
 Routing Protocols
 IP Header Compression
 IP Payload Compression
Typical VSAT Is Actually A Hybrid Device:

5. VSATs Generate Bandwidth Efficiencies
Higher Layer Acceleration and Optimization through…
 HTTP Prefetch
 TCP Spoofing, ACK Reduction, Selective
Retransmission
 IP Header and Payload Compression
Application
Transport
Network
Data Link
Physical
InternetModel
Lower Layer Efficiency through…
 DVB-S2 with Adaptive Coding and Modulation
(Forward Channel)
 Frequency Division/Time Division Multiple
Access (Return Channel)
Satellite Bandwidth Is
Limited Resource
VSAT Systems
Maximize Efficiencies

6. Key Components For a VSAT Network
Satellite
Remotes
Hub or Gateway
Internet or
Corporate Network

7. Why VSAT
Ubiquitous
Reliable
and Consistent
Scalable
and Manageable
Diverse
Uniform SLA and QoS Across Footprint
Simple Network Architecture
Independent of Terrestrial
VSAT Complements Terrestrial Solutions To Enable
Services To Un-Served And Under-Served Areas

8. VSAT For Home
In North America, as of 2011, there are
over 1 million households using VSAT to
access the internet

9. VSAT For Business
Retail Banking
Oil Exploration
Lottery
VSATs Used By
Enterprises For
Remote Connectivity
Primarily Used For
Locations Which Are
Underserved By
Terrestrial

10. VSAT For High Availability
Terrestrial
VSAT
DSL
MPLS
etc
VRRP
with PBR
Remote Branch
Corp HQ
Satellite to Back Up Terrestrial
Satellite to Load Share Terrestrial
Satellite Enables True Path Diversity

11. VSAT For Mobility
Fly-a-way VSAT
Man Pack VSAT
On The Pause VSAT
Maritime VSAT
Aeronautical VSAT

12. Considerations To Satellite: Latency
Satellite Orbit ~ 35,000 km Above Earth
Physical Delay Is About 250 ms roundtrip
Protocol Processing Adds ~300-500 ms
“spoofing”
Protocols Such As TCP Can Be
“Spoofed” or “Accelerated”
Link Is Terminated At The VSAT
Enables Fast Startup and Fast
Transfer
HTTP Object Pre-Fetch Enables
Fast Delivery of HTTP Objects

13. Satellite Frequencies
Ka band 26.5 to 40 GHz
K band 18 to 26.5 GHz
Ku band 12 to 18 GHz
X band 8 to 12 GHz
C band 4 to 8 GHz
S band 2 to 4 GHz
L band 1 to 2 GHz
Size of
Antenna
Impact of
Rain

14. Considerations To Satellite: Rain Fade
Atmospheric Moisture Attenuates Satellite Signal
Effect Is Greater At Higher Frequencies (eg, Ku and Ka)
Rain Fade Mitigation Techniques:
Forward Channel
• DVB-S2 with Adaptive Coding and Modulation
• Uplink Power Control
Return Channel
• Adaptive Coding
• Symbol Rate Change
• Uplink Power Control

15. Future Of VSATs
1990 2000 2010
1990 2000 2010
1-5 Mbps
9.6 kbps
$$$$
$
Significant increase
in throughput and
performance
Significant decrease
in cost of service
and hardware
New Ka-Band Systems Promise To Provide More Bandwidth At Less Cost

16. This is the end of this session, Hope
you enjoyed it and found it helpful.
You are most welcome to visit this
web site again and watch other video
tutorials in your areas of interest.
VSAT Basics