Delivery Methods
There are three basic methods for delivering internet service: via optic fiber, copper wire, or radio. I'll explain and expand on these below.
Optic Fiber
Optic fiber is generally not an option in poor countries - and especially in poor neighborhoods! However, technically it provides a low-noise, high-bandwidth medium. The signal must be amplified if the route is long.
Wire Delivery
Twisted Pair
Twisted pair is used for ordinary telephone systems. has many more twists per unit length than ordinary telephone line. This reduces the high-frequency signal that is lost to radiation and allows much higher bandwidth. The wire is labeled 'Category 5' or 'Category 6', while ordinary phone wire is labeled 'Category 3'.
Coaxial Cable
Coaxial Cable systems, originally developed for television, provide higher bandwidth and distances than DSL. This is because the cable is co-axial, that is to say that a central wire is surrounded by a shield, and this combination can be further shielded. This makes the loss lower and the noise lower, and the coaxial cable allows for much higher bandwidth.
Radio Delivery
What I'm calling 'radio delivery' includes methods that have no physical connection between sender and receiver. Radio delivery is affected by both the frequency of the carrier and the method of encoding the signal.
Packet Radio was developed by radio amateurs (ham operators) to send data. The early experimentation was done over (relatively) low frequencies (around 100 MHz). It is still used in emergency situations.
Cellular data uses the cellular telephone network to transmit data to portable or fixed devices. It uses relatively high frequencies (around 1 GHz). Power levels are limited, limiting the useful distance to several kilometers. The carrier frequencies are frequently blocked or reflected, making reception in canyons (including large cities) more difficult. In Nicaragua the Cellular providers are Claro and Movistar
WiFi is widely used, and works very well over distances around ten meters. Power levels are strictly limited, which limits the distance. WiFi uses frequencies similar to those used by cellular providers.
Satellite Internet transmission allows for communication far from populated area. However, because the satellites are so far from humans, the antenna must be large (1-2 meter diameter) to gain sufficient bandwidth, and power is limited at the satellite (because the don't have a large power source conveniently nearby). This makes the equipment expensive. Because the satellites are much more expensive to deploy (several thousand USD for antenna and radio modem) than ground-based services, the monthly charges are higher than the alternatives (at least 200 USD per month). But it is available nearly everywhere (for a price). HughesNet is a major supplier, as is Iridium, which uses the voice system.
WiMax is an evolution of WiFi that allows for greater distance than WiFi but without the need for a physical connection.
WiMax
WiMax is available in the Managua area through Yota. Their coverage map includes Ciudad Sandino. Monthly cost is around USD 50 with an annual contract, and daily or monthly plans are available.
WiMax Modems
It is possible to buy a USB-sized WiMax transceiver (radio transmitter, receiver, and modem) that will plug into any computer for around USD 75. Yota also offers small modems with built-in antennas, battery power, and WiFi. Prices range up to USD 400.
WiMax Antenna
Addition of an external directional antenna will increase the range of the device from the central station. These antennas are available from USD 75 up, depending on the style. Pictures of different antenna styles are available here. A tutorial on WiMax antennas may help.
On the customer end, a strongly directional antenna, pointed at the central office tower, will provide the best communication. (This is in opposition to the need at the central office tower, which wants to cover a broad area.) A flat panel antenna 45 cm square can provide a narrow (15 degree) pattern and high (18 db) gain.
The antenna will probably attract lightning, and must be protected (for about USD 75 plus installation).
A remote antenna will require special cable to prevent the signal captured by the antenna from being dissipated and polluted by electrical noise. This cable (LMR-400) is expensive and stiff.
The antenna will probably attract lightning, and must be protected (for about USD 75 plus installation).
A remote antenna will require special cable to prevent the signal captured by the antenna from being dissipated and polluted by electrical noise. This cable (LMR-400) is expensive and stiff.
