VERY SMALL APERTURE TERMINAL VSAT BASED RURALRemote NETWROK

VERY SMALL APERTURE TERMINAL (VSAT) BASED RURAL/Remote NETWROK KING FAHD UNIVERSITY OF PETROLEUM & MINERALS DEPARTMENT OF ELECTRICAL ENGINEERING EE 672: Satellite Communications 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 ä ä ä 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 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 ä ä ä ä 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 2 B 30. 5 E (KU band) ARABSAT transponder EIRP 47 d. BW Transponder Bandwidth 36 MHZ Transponder Noise Temperature (Ts) 500 k Maximum antenna gain (TX & RX) 34 d. B 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 50 d. B (uplink) & 49 d. B (downlink) VSAT transmission power 2 W VSAT antenna gain 47. 5 d. B uplink & 46. 5 d. B downlink VSAT antenna diameter 2 meter VSAT antenna efficiency 65 % VSAT noise temperature 147. 8 K Total inbound C/N at Hub 17. 7 d. B over 10 d. B threshold Total inbound C/N at VSAT 12. 96 d. B over min 6. 0 d. B threshold System Bandwidth 36 MHZ (1 transponder), 18 MHZ inbound and 18 MHZ for outbound link. System capacity (5% blocking) 566 channels (up to 5400 if 9. 6 kbps)

Multiple Access Scheme v Star hub configuration with frequency division multiple access, demand assigned single carrier per channel (DAMA SCPC). v 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. v 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 v. Processing delay at the VSAT terminal = 50 ms v. Retransmission delay due to error (BER 10*-6) = 0 (Negligible) v. Satellite delay = 253 ms (one way round trip) v. Other terrestrial and processing delays = 50 ms (may be longer for database applications) v. Approximate 1 way trip delay = 50+50+253 = 350 ms = 0. 35 seconds. v. This will be doubled (0. 70 seconds) if the call is from VSAT site to VSAT site.

Cost Considerations Cost/5 years Cost Per Month $2, 000. 00 $33. 33 $700. 00 $11. 67 Spare parts $200. 00 $3. 33 Maintenance per Year $500. 00 $2, 500. 00 $41. 67 Hub Lease Cost Per Year $40, 000. 00 Satellite (36 MHz) Bandwidth Lease/Year $1, 800, 000. 00 License One Time Fee (Approx) $8, 000. 00 Total Estimated Cost $9, 213, 400. 00 $153, 556. 66 Cost per channel (90) $102, 371. 11 $1, 706. 19 Channel cost/min $0. 04 VSAT Equipment $2, 000. 00 Installation $200, 000. 00 $3, 333. 33 $9, 000. 00 $150, 000. 00 $8, 000. 00 $133. 33

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 Minute s Average calls/day within Network 5 Minute s Monthly Fee/user $3. 00 Call cost/min within loop $0. 10 Call cost/min within Network $0. 35 Total income/Month $100, 5 00. 00 Operation Cost for 45 trunked channels(50%)/Month $76, 77 6. 67 Revenue from Hassai Area only $23, 72 3. 33

Conclusion and Future Work ä ä ä 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 Inter. Science (www. interscience. wiley. com). DOI: 10. 1002/sat. 819 [2] VSAT NETWORKING FOR BANKING D. J. Atkinson [3] www. arabsat. com [4] VSAT Networks, 2 nd Edition, G. Maral [5] http: //www. nitehawk. com/rasmit/offset. html (offset antenna design) [6] www. googleearth. com [7] www. tracks 4 africa. 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