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Connectivity Options

Home > THE BASICS > Telecenter Model > Connectivity Options

 

 

 

WiFi Connectivity

Diagram of WiFi Connectivity
The WiFi connectivity scenario consisted of a network of off-grid telecenters with one centrally located telecenter acting as a wireless ISP (WISP) to two remote telecenters. The WISP receives its Internet connection through a VSAT installed on site, and distributes Internet access to the remote telecenters through a WiFi fixed wireless spread spectrum network. Depending on the distance and the quality of the wireless connection, the WISP would transmit data to the remotes at rates ranging from 1 Mbps to 11 Mbps, although the speed of Internet access would ultimately be limited by the VSAT bandwidth, which might realistically be 64kbps.

The wireless network in this scenario has a point-to-multipoint configuration with line of sight (LOS) between the WISP and the remote telecenters. Depending on the local terrain and sources of interference, it is realistic to expect a range of one to ten kilometers between telecenters of this type of technology and configuration. In some cases it is possible to achieve longer distances using high gain antennas, either by putting the antennas on higher masts or installing repeater nodes.

The additional energy demand entailed by spread spectrum connectivity at the remote telecenters is fairly low, ranging from 30.0 to 42.6 Watt hours (see table below). These calculations are based on the assumption that the connectivity equipment remains powered in standby mode when the telecenters are closed. Spread spectrum systems in the WiFi family have relatively low power requirements because their output power (and hence range) is limited by regulation. For short-range links of a few kilometers, spread spectrum technology is a good solution for speedy, low-power data communications.

Additional Telecenter Energy Demand with WiFi Connectivity
Telecenter Size
Operating Mode
Estimated Usage (hours)
Power Consumption
Average daily Watt hours
Small Telecenter
transmitting
1.1
10.0
9.0
receiving
2.0
1.8
3.0
standby
21.0
1.0
18.0
subtotal
30.0
Medium Telecenter
transmitting
1.8
10.0
15.0
receiving
3.3
1.8
5.0
standby
6.0
1.0
16.3
subtotal
36.3
Large Telecenter
transmitting
2.5
10.0
21.0
receiving
4.6
1.8
7.0
standby
4.0
1.0
14.6
subtotal
42.6

 

Packet Radio Connectivity

Diagram of Packet Radio Connectivity

The narrowband packet radio option uses a terminal node controller and an amateur radio transceiver for low-speed wireless data transfer. Packet radio hardware and software can be added to HF, VHF, UHF radio systems that have a long history of use in rural areas for open-air voice communications. The use of packet radio to provide internet access for rural telecenters has been pilot tested in Honduras in a project supported by ITU and Hondutel. Packet radio is being used to connect multipurpose community telecenters in the towns of Santa Lucia and Valle de Angeles to smaller telecenters in a number of villages surrounding the main towns. The power supply for nodes and repeaters is one of the main costs for this type of connectivity solution (ITU, 2001).

For this connectivity scenario, Winrock chose equipment in the 2 m amateur radio band (144-145 MHz), with a transmitter output power level of 20 W. The system supports data rates ranging from 9600 baud (using 12.5 kHz of spectrum) to 153 k baud (using 200 MHz). Winrock also assumed that the packet radio system would be powered only during telecenter operating hours and that the equipment would be shut off and disconnected, consuming no electricity, at other times.

Additional Telecenter Energy Demand with Packet Radio Connectivity
Telecenter Size
Operating Mode
Estimated Usage (hours)
Power Consumption
Average daily Watt hours
Small Telecenter
transmitting
1.1
63.4
57.1
receiving
2.0
4.3
7.2
standby
8.0
2.2
14.8
subtotal
79.0
Medium Telecenter
transmitting
1.8
63.4
95.1
receiving
3.3
4.3
12.0
standby
6.0
2.2
11.1
subtotal
118.2
Large Telecenter
transmitting
2.5
63.4
133.2
receiving
4.6
4.3
16.8
standby
4.0
2.2
7.4
subtotal
157.4

Based on the usage assumptions indicated in the table above, packet radio connectivity increased daily telecenter energy requirements by 79.0 Wh for the smallest telecenter, 118.2 Wh for the medium telecenter, and 157.4 Wh for the large telecenter. Of the three wireless scenarios, narrowband packet radio installation are most likely to diverge significantly from the estimates of energy demand presented here. This is due to the wide range of equipment configurations, component quality and transmitter output power levels that can be used to achieve packet radio connections.

With the addition of packet radio connectivity, total telecenter investment increased by $2,000 on average.

VSAT Connectivity

Diagram of VSAT Connectivity


The VSAT connectivity option is a low-power system that is capable of supporting telephony and data services. VSAT systems ave become a familiar component of remote telecenters due to their ability to offer connectivity in virtually any location. There are a variety of benefits and drawbacks to the use of VSATs; however, these are outside the scope of this particular discussion. What is important in the energy context is to raise awareness that there are low-power VSATs that are designed for off-grid usage, and they consume as little as 25-30 W on average.

The table below shows the additional daily energy requirement associated with VSAT.

Additional Telecenter Energy Demand with VSAT Remote Station
Telecenter Size & Usage Assumptions
Additional Daily Watt-hours
VSAT Equipment Costs
Small - 3 hours/day
256.3
$3,000
Medium - 5 hours/day
295.7
$3,000
Large - 7 hours/day
335.1
$5,500

One of the reasons these figures are so high is that the VSATs were assumed to remain on standby mode during the nighttime and on Sunday hwen the telecenter was closed. This assumption was made because some VSAT manufacturers discourage users from shutting off the power to the VSAT on a frequent basis. Not all satellite receivers need to follow this practice, however, so it is worthwhile to check with the supplier.

VSAT equipment costs were chosen to represent a fairly advantageous market pricing for thin route rural telephony/internal VSAT terminal and receiver equipment. In many countries, factors such as vendor markup, import duties and regulations will increase costs for the basic equipment. The large telecenter was assigned an upgraded VSAT package in order to support four telephone lines (three telephones plus a separate fax line) plus Internet access, whereas the smaller telecenters sufficed with three telephone lines.

When combined with the low-power desktop computer option, the VSAT scenario increased total ICT plus energy costs for the telecenters by $3,806 for the smaller telecenter, $3,884 for the medium telecenter, and $6865 for the large telecenter.