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Which Optical Fiber Types Better for FTTH Network and Why?

Posted By: technopediasite
Which Optical Fiber Types Better for FTTH Network
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For the design of an FTTx network or link, it needs to establish and accomplishing the following parameters,Optical fiber types is also very important for the FTTH network, So today I would like to provide the information about the which Optical Fiber types better for FTTH network: 
Maximum transmission distance
Optical attenuation balance for the system
 Fiber type
 Attenuation for connectors
Attenuation by union or splice
 Maximum reflection (backward)
Connector types

 Range of aging or mechanical lifetime.

Optical fiber types
The choice of optical fiber is determined by various parameters, being the most important and restrictive dispersion and optical attenuation. The advantages of single mode fiber (high transmission capacity and low optical attenuation) make this medium as the most attractive for FTTx networks. So, always single-mode fibers are used on FTTx networks.

The fact of using single-mode optical fibers in FTTH network allows homogenizing access to the rest of the network which already uses this type of fiber, giving it transparency and uniformity. It also simplifies the operation, maintenance and development. Therefore, it recommends the usage of this type of fiber for FTTH access network, as recommended by IEEE 1000Base-LX and 10GBASE-LX. It can identify as the best options the usage of fibers G.652D or G.657A and G.657B for FTTH.

Newer fibers which conform to the G.652.D standards eliminate the water peak attenuation and allow for full operation of all 20 ITU CWDM channels in metropolitan networks. ITU-T G.652D defines a full spectrum, low water peak fiber with low PMD and represents the most comprehensive standard for standard single-mode fibers.

But the private service providers are demanding that the cable manufacturers adhere to ITU-T G.657 standards. This standard describes two categories of singlemode optical fiber suitable for use in the access networks.

Category A fibers are suitable for transmission in the O, E, S, C and L-band (throughout the 1260 to 1625 nm range). Fibers in this category have the same transmission and interconnection properties as G.652.D fibers with improved bending loss and tighter dimensional specifications.

Category B fibers are suitable for transmission at 1310, 1550, and 1625 nm for restricted distances that are associated with in-building transport of signals. These fibers have different splicing and connection properties than G.652 fibers, but are capable at very low values of bend radius.

Number of Optical fibers per user
When designing a network, you have to take into account the current needs and projections regarding future service requirements referred, such as expansion of basic services, inclusion of alarms, etc.

The total number of fibers per end user or subscriber is determined by the degree of utilization of active opto-electrical components that exist on the network. Most point to point systems are based on the use of two fibers per link, one dedicated to upstream and the other for downstream. But in this project, and given that it will use the WDM technology, the uplink and downlink channels will travel through the same fiber but at different wavelengths. This implies that the number of fibers and the connectors are cut in half, saving cost and space.

Type of unions between Optical Fibers

Fiber connections which have better performance in terms of losses concerns are the fusion splices, and are the most commonly used today. No but also tend to be frequent mechanical splices.

A good fusion should typically have a loss of about 0.1 to 0.15 dB of attenuation for single-mode optical fiber according to ITU recommendation G.652. The attenuation produced by the union of fibers is not critical in many systems, but in order to ensure a lifetime of more durable splice, it is recommended to fusion if attenuation is greater than 0.3 dB.

Moreover, the maximum recommended attenuation for any kind of fusion or mechanical splice should not exceed 0.3 dB loss. And it is the fusion joints which offer better performance and fulfilling, as a rule, such a requirement.

Special care is needed when estimating the attenuation by fusion or splices. The estimate of this parameter is not always accurate, and although is not required the metric verification of each union, it is necessary to verify the complete attenuation of the link to study the contribution of each union to the system.

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