The previous blog post about fiber to the home (FTTH) described the design of the fiber network for urban areas where homes are built side by side along a street. Please read the Blog “The technology of fiber to the home (FTTH) networks” before reading this one.
To summarize the previous post, an optical fiber cable is installed from the ISP central office to a location on the street where an optical splitter is installed. The splitter might be one to16 way, one to 32 way or one to 64 way. If the cable from the central office is strung along utility poles then the optical splitter will be installed on the utility pole. If the cable is underground then the splitter will be underground in a utility box. Fiber drop cables connect the optical splitter to each home in the street. The #fiber network is illustrated in the following diagram.
A rural area may have a homestead every few miles along a minor road. A fiber cable is run from the central office along the side of the rural road. If utility piles are installed along the side of the road then the fiber cable can be strung along the utility poles. If there are no utility poles then the fiber cable can be buried in a trench along the side of the road. At each homestead location a drop cable fiber is split off from the main fiber and run to the homestead along utility poles or underground. The optical splitter in this case is different from the optical splitter installed in the urban environment that may have 16, 32 or 64 taps. The #rural optical splitter has one tap with a differential attenuation factor. The tap for the drop cable may have 5% or 10% of the light energy to connect to the homestead. 90% or 95% of the light energy is passed along the main cable for the next homestead. A 5% energy tap will provide the same light energy per household as a 1:20 splitter. A 5% tap will permit the installation of 20 taps along the length of the main fiber cable. The length of the main cable will be reduced. Without taps the main cable can extend up to 70 Km, however with taps the length will be less and will depend on the number of cable taps. The next diagram illustrates a rural fiber network.
Some homesteads are beyond the maximum distance of the fiber, which is 70Km for one run using PON technology. Installing powered repeaters permits the run to be extended. However the homestead will have to be within a radius of a central office where a wholesale fiber connection can be provided. It will not be possible to connect every home using fiber. A small percentage of homes will rely on wireless technology to connect to the Internet. The technology that offers the greatest flexibility for remote and off-grid locations at the present time is low earth orbit (LEO) satellites and Starlink is the likely provider.
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