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VERY SMALL APERTURE TERMINAL (VSAT) BASED RURAL/Remote NETWROK

VERY SMALL APERTURE TERMINAL (VSAT) BASED RURAL/Remote NETWROK. May, 2007. KING FAHD UNIVERSITY OF PETROLEUM & MINERALS DEPARTMENT OF ELECTRICAL ENGINEERING. EE 672: Satellite Communications Project. Project Overview. Project Agenda. VSAT Overview Proposed System Propagation Effects

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VERY SMALL APERTURE TERMINAL (VSAT) BASED RURAL/Remote NETWROK

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  1. VERY SMALL APERTURE TERMINAL (VSAT) BASED RURAL/Remote NETWROK May, 2007 KING FAHD UNIVERSITY OF PETROLEUM & MINERALS DEPARTMENT OF ELECTRICAL ENGINEERING EE 672: Satellite Communications Project Project Overview

  2. 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)

  3. 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.

  4. Why VSAT • 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.

  5. Why WLL • Shorter implementation time • The costs to connect a customer are independent of the distance • Higher flexibility • Lower maintenance costs

  6. Proposed System • 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.

  7. Proposed System - Continued

  8. 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 pro-portion to the active circuits and their holding times, this is ideally suited for voice traffic and data traffic in batch mode.

  9. 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.

  10. Cost Considerations

  11. System Scenarios

  12. VSAT/WLL Applied Scenario (Hassai – Sudan) population 30*30 km is approximately 6335.

  13. Hassai – Sudan: VSAT/WLL Solution

  14. Call charges

  15. Conclusion and Future Work • 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.

  16. 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

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