Transcript Vulnerability Assessment Tool - VSAT

VERY SMALL APERTURE
TERMINAL (VSAT) BASED
RURAL/Remote NETWROK
KING FAHD UNIVERSITY OF PETROLEUM & MINERALS
DEPARTMENT OF ELECTRICAL ENGINEERING
EE 672: Satellite Communications Project
Project Overview
May, 2007
Project Agenda
VSAT Overview
Proposed System
Propagation Effects
Link budget for inbound link
Link budget for Outbound link
Hub Earth Station
VSAT Antenna
Multiple Access Scheme
System Applications with respect to Remote Areas
Delay considerations and cost estimates
Rural/Remote Areas Scenarios
System Application Scenario (HASSAI)
Conclusion and future work
(IRAQ scenario – GSM over VSAT)
VSAT Based Rural Network
Introduction
Many inhabitants of rural remote areas currently have no way of
communicating locally or with the outside world as no services
are available in their poor remote regions. As a solution, a
VSAT associated with a local loop is employed.
Voice and data communications are essential to the economic
development of a region, and it has been shown that traffic
increases rapidly as soon as the service is available.
Why VSAT
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VSATs guarantee seamless global communication even across the last mile.
A VSAT Network can be provided through a lease arrangement with fixed
transmission costs regardless of distance .
VSAT Networks offer superior flexibility and performance. Adding a site is
quick and easy. Mobility is an other advantage
VSATs service charges depend on the bandwidth, which is allocated to
network in line with your requirements. Whereas in a leased line, you get a
dedicated circuit in multiples of 64 Kbps whether you need that amount of
bandwidth or not.
Due to their high demand and mass production, VSAT terminals prices are
falling, which makes it affordable and the choice to most business sites.
Why WLL
•Shorter implementation time
•The costs to connect a customer are independent of the distance
•Higher flexibility
•Lower maintenance costs
Proposed System
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The types of customers the system is targeting are residence/non
residence/corporate offices.
The system consists of a single hub Earth station, a geostationary satellite (
ARABSAT 30.5 E global coverage) and a number of VSAT terminals.
Each VSAT earth station send and receives 64 Kbps data stream to and from the hub
using BPSK and half rate error correction (FEC) coding giving a bit rate of 128 Kbps.
Using filters (0.25) gives a channel bandwidth of 160 KHZ. Adding 40 KHZ guard
band between channels gives a total bandwidth of 200 KHZ per channel.
Data from VSAT to hub (inbound link) is (SCPC-DAMA) .
Data from hub to VSAT is sent using a continuous time division multiplexing (TDM)
stream of packets.
The system can be used to transmit voice, data and fax.
System capacity is approximately 566 available 64 Kbps trunked channels with 5%
blocking probability. Can reach up to 5540 channels if voice is compressed to 9.6
Kbps.
Proposed System - Continued
Satellite used
ARABSAT 2B 30.5 E (KU band)
ARABSAT transponder EIRP
47 dBW
Transponder Bandwidth
36 MHZ
Transponder Noise Temperature (Ts)
500 k
Maximum antenna gain (TX & RX)
34 dB
Uplink frequency (inbound - VSAT to SAT)
14 GHZ
Downlink frequency (inbound - SAT to Hub)
12.521 GHZ
Uplink frequency (outbound - Hub to SAT)
14.02 GHZ
Downlink frequency (outbound – SAT to VSAT)
12.539 GHZ
Range to VSAT terminals
38000 Km
Max Hub transmission power
200 W
Noise temperature of Earth station
150 K
Hub antenna gain
50dB (uplink) & 49 dB (downlink)
VSAT transmission power
2W
VSAT antenna gain
47.5 dB uplink & 46.5 dB downlink
VSAT antenna diameter
2 meter
VSAT antenna efficiency
65 %
VSAT noise temperature
147.8 K
Total inbound C/N at Hub
17.7 dB over 10 dB threshold
Total inbound C/N at VSAT
12.96 dB over min 6.0dB threshold
System Bandwidth
36 MHZ (1 transponder), 18MHZ inbound and 18MHZ
for outbound link.
System capacity (5% blocking)
566 channels (up to 5400 if 9.6 kbps)
Multiple Access Scheme
 Star hub configuration with frequency division multiple access, demand
assigned single carrier per channel (DAMA SCPC).
 A pool of satellite channels are used, 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 proportion to the active circuits and their holding times, this is ideally suited for
voice traffic and data traffic in batch mode.
Delay Considerations
Processing delay at the VSAT terminal = 50 ms
Retransmission delay due to error (BER 10*-6) = 0 (Negligible)
Satellite delay = 253 ms (one way round trip)
Other terrestrial and processing delays = 50 ms (may be longer for database
applications)
Approximate 1 way trip delay = 50+50+253 = 350 ms = 0.35 seconds.
This will be doubled (0.70 seconds) if the call is from VSAT site to VSAT site.
Cost Considerations
VSAT
Cost/5 years
Cost Per Month
$2,000.00
$33.33
Equipment
$2,000.00
Installation
$700.00
$700.00
$11.67
Spare parts
$200.00
$200.00
$3.33
Maintenance per Year
$500.00
$2,500.00
$41.67
Lease Cost Per Year
$40,000.00
$200,000.00
$3,333.33
Satellite (36 MHz)
Bandwidth Lease/Year
$1,800,000.00
$9,000,000.00
$150,000.00
License
One Time Fee (Approx)
$8,000.00
$8,000.00
$133.33
Total
Total Estimated Cost
$9,213,400.00
$153,556.66
$102,371.11
$1,706.19
Hub
Cost per channel (90)
Channel cost/min
$0.04
System Scenarios
VSAT/WLL Applied Scenario (Hassai –
Sudan)
population 30*30 km is approximately 6335.
Hassai – Sudan: VSAT/WLL Solution
Call charges
Estimated population
6335
Estimated Subscribers (15%)
1000
Average calls/day within loop
15 Minutes
Average calls/day within Network
5 Minutes
Monthly Fee/user
$3.00
Call cost/min within loop
$0.10
Call cost/min within Network
$0.35
Total income/Month
$100,500.00
Operation Cost for 45 trunked channels(50%)/Month
$76,776.67
Revenue from Hassai Area only
$23,723.33
Conclusion and Future Work
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Similar Systems already tested successfully in rural areas in Peru, many parts of
Africa, India, Malaysia and other countries.
System can be upgraded to deploy GSM through VSAT (Iraq scenario), ATM
machine, POS, DBS, etc.
More work can be done to reduce the overall system cost and improve system
delay, by considering LEO orbits or using a space loop for example.
References
[1] INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING
Int. J. Satell. Commun. Network. 2005; 23:307–321. Published online in Wiley InterScience
(www.interscience.wiley.com). DOI: 10.1002/sat.819
[2] VSAT NETWORKING FOR BANKING D.J. Atkinson
[3] www.arabsat.com
[4] VSAT Networks, 2nd Edition, G. Maral
[5] http://www.nitehawk.com/rasmit/offset.html (offset antenna design)
[6] www.googleearth.com
[7] www.tracks4africa.com
[8] INTELSAT Satellite-based rural telephony: effective solutions for infrastructure development
[9] THE WLL/VSAT RURAL TELEPHONY TRIAL IN PERU
[10] Cable and Wireless Global VSAT – Iraq Case Study
[11] VSAT Networks – G. Maral