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Submitted by KDD Engineering and Consulting Inc.
1. Introduction
2. Goals of the VSAT project
3. Outline of the project
4. Lifetime cost advantages of a rural VSAT system
5. Technical System Specifications
6. Contact point

1. Introduction
The Republic of Paraguay is a landlocked country located in the central portion of South America. The country covers an area of 400,000 square kilometers and has a population of 5 million. Outside of the main cities there are vast areas, such as Chaco in the north, where the population is thinly scattered. There are approximately 250,000 telephone subscribers in the country.
The Republic of Paraguay’s telecommunication agency, henceforth referred to as ANTELCO, oversees the country's electricity, telecommunications, and broadcasting networks. ANTELCO recently introduced a trial VSAT system to improve telephone circuits linking various underpopulated areas with the capital city, Asunción. The initial costs of establishing the VSAT network were lowered by utilizing an old Intelsat standard A earth station that had become superannuated as the network Hub. The VSAT project was carried out as part of PG-P10, a project to expand satellite earth station facilities in Paraguay. PG-P10 carried out between 1995 and 1999 on the basis of a soft loan from Japan's Official Development Assistance (ODA).
This report provides a practical example of applying a VSAT system via Intelsat satellites in underpopulated areas.
2. Goals of the VSAT project
In the Republic of Paraguay, there are only a few cities other than Asunción with more than 10,000 telephone subscribers. These cities are connected with fiber optic cables and a microwave network. While these urban areas have been expanding their fixed and mobile telephone networks, upgrading to digital switching, and installing Signalling System Number 7, the smaller towns have been left behind. The telephone circuits connecting small cities like Tacuati, in the Chaco region, have used VHF wireless systems. The VHF systems can handle only a small number of low quality circuits.
The VSAT system was introduced on a trial basis as the most appropriate method of improving the quality and number of telephone circuits connecting Asunción with such rural areas.
3. Outline of the project
ANTELCO requested a plan for the improvement of the telephone network in underpopulated regions of the Republic of Paraguay, keeping in mind future expandability of the VSAT system. The specified requirements for the system focused on the following: a. Use of existing C-band, Intelsat standard A earth station facilities. b. Minimization of initial cost, with provisions for future upgrade to a DAMA system and expansion of the number of VSAT terminals. c. Limited number of VSATs for test operation. d. Possibility of providing data transmission for computer communications.
On this basis, KEC designed a solution employing C-band frequencies, an SCPC-DAMA system, six VSATs for test operation, and datacommunication circuits in addition to telephone circuits. Each of the remote VSATs was configured to for two to four telephone lines. The entire test system provided 16 telephone lines plus four data lines.
Figure 3-1: Proposed VSAT facility sites

3.1 VSAT network configuration
The VSAT system will consist of a domestic switching system at the central office in Asunción (Central II), a Hub station with a 32-meter antenna at the Aregua earth station facility, Intelsat satellite 328.5° E, and remote VSAT stations with 2.4-meter antennas.
The first location chosen for a remote VSAT station in the trial was Tacuati, located 350 kilometers north of Asunción in the state of Concepción. This site was used to introduce the VSAT system and to train local staff. For the other five stations, ANTELCO will select sites from the proposed site list, and construct the stations themselves.
As of January 2000, the locations at which facility construction had been decided upon or completed were as follows:
-- Tacuati
-- Ype Jeu
-- Laureles
-- Aregua
-- Yabebyry
-- Pozo Hondo
The locations of these existing and proposed sites are indicated in Figure 3-1.
The initial equipment involved in the project is as follows:
1) Central exchange system : 16 channels 2w ( FXO/FXS )
2) Transmission line (STM-4): 2Mbps PCM-MUX 2w ( FXO/FXS ) 2Mbps V35 data 64Kbps ( V.35 data )
3) Hub station ( retrofitted ) : ANT 32m, X1 Previous INTELSAT std.A
4) VSAT Terminal ( C-band ) : ANT 2.4m, X6
Figure 3-2 shows the configuration of the equipment described above.

Figure 3-2: VSAT Subsystem Configuration
The network consists of one Hub station and six VSAT stations, all located within Paraguayan territory. To reduce equipment costs, the Hub station uses components of an obsolete standard A station belonging to ANTELCO. The earth station was originally directed at an Intelsat satellite over the Atlantic Ocean, but was taken out of service when the PG-P10 project constructed new earth station facilities. Reused components consist of antenna and RF equipment, as illustrated in Figure 3-3.
The system supports permanent assignment multiple access (PAMA) transmission mode for voice and data services in a star topology. The system can also be upgraded for DAMA transmission mode according to future demand.
Ordinary telephone 2-wire copper line was installed between the VSAT and subscriber's premises, over distances ranging from tens of meters to hundreds of meters.

Figure 3-3: System Configuration for ANTELCO's Main VSAT Facilities
Note 1
Maximum system capacity of satellite channels is 2000 CH / 36MHz

Note 2
BOD : Bandwidth On Demand
PAMA : Permanent Assignment Multiple Access
DAMA : Demand Assignment Multiple Access
IUD : Indoor Unit
MODEM : Modulator Demodulator
U/C : Up converter
D/C : Down converter
HPA : High Power Amplifier
LNA : Low Noise Amplifier
RF COMB : RF Combiner
RF DIV : RF Divider

3.2 Images from the ANTELCO VSAT project
The Hub station, shown in Figure 3-3, employs a 32-meter diameter antenna which was originally directed at an Intelsat satellite over the Atlantic Ocean. The small antenna in Figure 3-4 was temporarily constructed for test purposes at the Aregua earth station facility.
Figure 3-3: Retrofitted hub station at Aregua Figure 3-4: Test VSAT at Aregua


Figure 3-5: Hub modems (left cabinet) and frequency converters (right cabinet) Figure 3-6: VSAT terminal at Tacuati city

Figure 3-7: ANTELCO office for VSAT in Tacuati

4. Lifetime cost advantages of a rural VSAT system
1. On routes extending more than 100 km, a rural VSAT system can generally reduce the total investment cost of extending the telephone network into rural areas compared to long haul microwave links. VSAT systems tend to be deployed when telephone services are provided to villages over an extensive service area with a limited budget. In such circumstances, a VSAT network can reduce initial costs while allowing for future expansion of the network according to an area’s stage of growth. A VSAT solution can be most economically attractive in cases where villages are distributed in a wide, unpopulated area such as the Chaco district in Paraguay.
The initial cost of the VSAT system described in this report was 75 million yen (0.7 million US$), inclusive of: o Main VSAT facilities (1 Hub + 6 VSATs) o PCM-MUX (voice and V.35 data) o Spare parts (VSAT and PCM-MUX) o Document fee (6 sets) o Installation (1 Hub + 1 VSAT terminal)
The Hub antenna and RF equipment consisted of existing, reused equipment, thus reducing expenditure compared to the purchase of a completely new Hub antenna system.
If ANTELCO had not made use of the existing 32m dish, it would have been required to install a new earth station dish of 10m in diameter. This would have added US$ 1 million to the total system cost. If the same size dish (32m diameter) were installed, it would have cost an additional US$ 3 - 4 million.
2. Installation of a VSAT terminal is relatively simple.
3. The VSAT terminals can be operated by remote control from the Hub station. For example, the carrier ON/OFF functions can be executed automatically. Therefore, no operational staff is necessary at the remote VSAT station.
4. It is easy to upgrade an SCPC DAMA system and to increase the number of VSAT terminals on the network at a later date.
5. Technical System Specifications
Table 5-1 Hub and VSAT Station Technical Specifications
VSAT Station HUB Station
1. RF Frequency C-Band C-Band
2. ANT Diameter 2.4m 32.0m (previously Std A)
3. TX power 5W 3KW
4. LNA 60K 55K
5. IFL cable Up to 100m -
Table 5-2 Hub Modem and VSAT IDU Technical Specifications
VSAT IDU HUB MODEM
1. Information Rate (Kbps)
Synchronous data 9.6 I 2048
Asynchronous data (on the voice card) 3.0 I 14.4 (at 17.5 Kbps transmission rate)0.3 I 14.4 (at 35.0 Kbps transmission rate)
2. Voice 32 Kbps (ADPCM), 16 Kbps (LD-CELP)
3. FEC Rate
Synchronous Data 1/2, 3/4, 7/8
Asynchronous data 1/2, 3/4
Voice 1/2, 3/4
4. Modulation BPSK, QPSK
5. User Interface
Synchronous Data RS-232C, RS-449/422, V.35, G703
Asynchronous data RS-232C
Voice 2W FXS, 2W FXO, 4W E&M
6. Power requirement AC 200I240V ±10%, 50I60Hz ±5%,
7. Power consumption Max. 500 VA (2W ODU) Max. 340 VA
8. Dimensions (H x W X D) (mm) 132 X 436 X 450 132 X 436 X 450
9. Environmental conditions
Operating temperature 0 to +40ºC
Humidity up to 95% (non-condensing)

6. Contact point
KDD Engineering and Consulting, Inc. (KEC) conducted this PG-P10 Project. If you have a question, please feel free to contact us.